text: /* Copyright (c) 2001 Matej Pfajfar.
   * Copyright (c) 2001-2004, Roger Dingledine.
   * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   * Copyright (c) 2007-2019, The Tor Project, Inc. */
  /* See LICENSE for licensing information */
  
  /**
   * \file connection.c
   * \brief General high-level functions to handle reading and writing
   * on connections.
   *
   * Each connection (ideally) represents a TLS connection, a TCP socket, a unix
   * socket, or a UDP socket on which reads and writes can occur.  (But see
   * connection_edge.c for cases where connections can also represent streams
   * that do not have a corresponding socket.)
   *
   * The module implements the abstract type, connection_t.  The subtypes are:
   *  <ul>
   *   <li>listener_connection_t, implemented here in connection.c
   *   <li>dir_connection_t, implemented in directory.c
   *   <li>or_connection_t, implemented in connection_or.c
   *   <li>edge_connection_t, implemented in connection_edge.c, along with
   *      its subtype(s):
   *      <ul><li>entry_connection_t, also implemented in connection_edge.c
   *      </ul>
   *   <li>control_connection_t, implemented in control.c
   *  </ul>
   *
   * The base type implemented in this module is responsible for basic
   * rate limiting, flow control, and marshalling bytes onto and off of the
   * network (either directly or via TLS).
   *
   * Connections are registered with the main loop with connection_add(). As
   * they become able to read or write register the fact with the event main
   * loop by calling connection_watch_events(), connection_start_reading(), or
   * connection_start_writing().  When they no longer want to read or write,
   * they call connection_stop_reading() or connection_stop_writing().
   *
   * To queue data to be written on a connection, call
   * connection_buf_add().  When data arrives, the
   * connection_process_inbuf() callback is invoked, which dispatches to a
   * type-specific function (such as connection_edge_process_inbuf() for
   * example). Connection types that need notice of when data has been written
   * receive notification via connection_flushed_some() and
   * connection_finished_flushing().  These functions all delegate to
   * type-specific implementations.
   *
   * Additionally, beyond the core of connection_t, this module also implements:
   * <ul>
   * <li>Listeners, which wait for incoming sockets and launch connections
   * <li>Outgoing SOCKS proxy support
   * <li>Outgoing HTTP proxy support
   * <li>An out-of-sockets handler for dealing with socket exhaustion
   * </ul>
   **/
  
  #define CONNECTION_PRIVATE
  #include "core/or/or.h"
  #include "feature/client/bridges.h"
  #include "lib/container/buffers.h"
  #include "lib/tls/buffers_tls.h"
  #include "lib/err/backtrace.h"
  
  /*
   * Define this so we get channel internal functions, since we're implementing
   * part of a subclass (channel_tls_t).
   */
  #define TOR_CHANNEL_INTERNAL_
  #define CONNECTION_PRIVATE
  #include "app/config/config.h"
  #include "core/mainloop/connection.h"
  #include "core/mainloop/mainloop.h"
  #include "core/mainloop/netstatus.h"
  #include "core/or/channel.h"
  #include "core/or/channeltls.h"
  #include "core/or/circuitbuild.h"
  #include "core/or/circuitlist.h"
  #include "core/or/circuituse.h"
  #include "core/or/connection_edge.h"
  #include "core/or/connection_or.h"
  #include "core/or/dos.h"
  #include "core/or/policies.h"
  #include "core/or/reasons.h"
  #include "core/or/relay.h"
  #include "core/proto/proto_http.h"
  #include "core/proto/proto_socks.h"
  #include "feature/client/dnsserv.h"
  #include "feature/client/entrynodes.h"
  #include "feature/client/transports.h"
  #include "feature/control/control.h"
  #include "feature/dirauth/authmode.h"
  #include "feature/dircache/dirserv.h"
  #include "feature/dircommon/directory.h"
  #include "feature/hibernate/hibernate.h"
  #include "feature/hs/hs_common.h"
  #include "feature/hs/hs_ident.h"
  #include "feature/nodelist/nodelist.h"
  #include "feature/nodelist/routerlist.h"
  #include "feature/relay/dns.h"
  #include "feature/relay/ext_orport.h"
  #include "feature/relay/routermode.h"
  #include "feature/rend/rendclient.h"
  #include "feature/rend/rendcommon.h"
  #include "feature/stats/rephist.h"
  #include "lib/crypt_ops/crypto_util.h"
  #include "lib/geoip/geoip.h"
  
  #include "lib/sandbox/sandbox.h"
  #include "lib/net/buffers_net.h"
  #include "lib/tls/tortls.h"
  #include "lib/evloop/compat_libevent.h"
  #include "lib/compress/compress.h"
  
  #ifdef HAVE_PWD_H
  #include <pwd.h>
  #endif
  
  #ifdef HAVE_UNISTD_H
  #include <unistd.h>
  #endif
  #ifdef HAVE_SYS_STAT_H
  #include <sys/stat.h>
  #endif
  
  #ifdef HAVE_SYS_UN_H
  #include <sys/socket.h>
  #include <sys/un.h>
  #endif
  
  #include "feature/dircommon/dir_connection_st.h"
  #include "feature/control/control_connection_st.h"
  #include "core/or/entry_connection_st.h"
  #include "core/or/listener_connection_st.h"
  #include "core/or/or_connection_st.h"
  #include "core/or/port_cfg_st.h"
  #include "feature/nodelist/routerinfo_st.h"
  #include "core/or/socks_request_st.h"
  
  /**
   * On Windows and Linux we cannot reliably bind() a socket to an
   * address and port if: 1) There's already a socket bound to wildcard
   * address (0.0.0.0 or ::) with the same port; 2) We try to bind()
   * to wildcard address and there's another socket bound to a
   * specific address and the same port.
   *
   * To address this problem on these two platforms we implement a
   * routine that:
   * 1) Checks if first attempt to bind() a new socket  failed with
   * EADDRINUSE.
   * 2) If so, it will close the appropriate old listener connection and
   * 3) Attempts bind()'ing the new listener socket again.
   *
   * Just to be safe, we are enabling listener rebind code on all platforms,
   * to account for unexpected cases where it may be needed.
   */
  #define ENABLE_LISTENER_REBIND
  
  static connection_t *connection_listener_new(
                                 const struct sockaddr *listensockaddr,
                                 socklen_t listensocklen, int type,
                                 const char *address,
                                 const port_cfg_t *portcfg,
                                 int *addr_in_use);
  static connection_t *connection_listener_new_for_port(
                                 const port_cfg_t *port,
                                 int *defer, int *addr_in_use);
  static void connection_init(time_t now, connection_t *conn, int type,
                              int socket_family);
  static int connection_handle_listener_read(connection_t *conn, int new_type);
  static int connection_finished_flushing(connection_t *conn);
  static int connection_flushed_some(connection_t *conn);
  static int connection_finished_connecting(connection_t *conn);
  static int connection_reached_eof(connection_t *conn);
  static int connection_buf_read_from_socket(connection_t *conn,
                                             ssize_t *max_to_read,
                                             int *socket_error);
  static int connection_process_inbuf(connection_t *conn, int package_partial);
  static void client_check_address_changed(tor_socket_t sock);
  static void set_constrained_socket_buffers(tor_socket_t sock, int size);
  
  static const char *connection_proxy_state_to_string(int state);
  static int connection_read_https_proxy_response(connection_t *conn);
  static void connection_send_socks5_connect(connection_t *conn);
  static const char *proxy_type_to_string(int proxy_type);
  static int conn_get_proxy_type(const connection_t *conn);
  const tor_addr_t *conn_get_outbound_address(sa_family_t family,
                    const or_options_t *options, unsigned int conn_type);
  static void reenable_blocked_connection_init(const or_options_t *options);
  static void reenable_blocked_connection_schedule(void);
  
  /** The last addresses that our network interface seemed to have been
   * binding to.  We use this as one way to detect when our IP changes.
   *
   * XXXX+ We should really use the entire list of interfaces here.
   **/
  static tor_addr_t *last_interface_ipv4 = NULL;
  /* DOCDOC last_interface_ipv6 */
  static tor_addr_t *last_interface_ipv6 = NULL;
  /** A list of tor_addr_t for addresses we've used in outgoing connections.
   * Used to detect IP address changes. */
  static smartlist_t *outgoing_addrs = NULL;
  
  #define CASE_ANY_LISTENER_TYPE \
      case CONN_TYPE_OR_LISTENER: \
      case CONN_TYPE_EXT_OR_LISTENER: \
      case CONN_TYPE_AP_LISTENER: \
      case CONN_TYPE_DIR_LISTENER: \
      case CONN_TYPE_CONTROL_LISTENER: \
      case CONN_TYPE_AP_TRANS_LISTENER: \
      case CONN_TYPE_AP_NATD_LISTENER: \
      case CONN_TYPE_AP_DNS_LISTENER: \
      case CONN_TYPE_AP_HTTP_CONNECT_LISTENER
  
  /**************************************************************/
  
  /** Convert a connection_t* to an listener_connection_t*; assert if the cast
   * is invalid. */
  listener_connection_t *
  TO_LISTENER_CONN(connection_t *c)
  {
    tor_assert(c->magic == LISTENER_CONNECTION_MAGIC);
    return DOWNCAST(listener_connection_t, c);
  }
  
  size_t
  connection_get_inbuf_len(connection_t *conn)
  {
    return conn->inbuf ? buf_datalen(conn->inbuf) : 0;
  }
  
  size_t
  connection_get_outbuf_len(connection_t *conn)
  {
      return conn->outbuf ? buf_datalen(conn->outbuf) : 0;
  }
  
  /**
   * Return the human-readable name for the connection type <b>type</b>
   */
  const char *
  conn_type_to_string(int type)
  {
    static char buf[64];
    switch (type) {
      case CONN_TYPE_OR_LISTENER: return "OR listener";
      case CONN_TYPE_OR: return "OR";
      case CONN_TYPE_EXIT: return "Exit";
      case CONN_TYPE_AP_LISTENER: return "Socks listener";
      case CONN_TYPE_AP_TRANS_LISTENER:
        return "Transparent pf/netfilter listener";
      case CONN_TYPE_AP_NATD_LISTENER: return "Transparent natd listener";
      case CONN_TYPE_AP_DNS_LISTENER: return "DNS listener";
      case CONN_TYPE_AP: return "Socks";
      case CONN_TYPE_DIR_LISTENER: return "Directory listener";
      case CONN_TYPE_DIR: return "Directory";
      case CONN_TYPE_CONTROL_LISTENER: return "Control listener";
      case CONN_TYPE_CONTROL: return "Control";
      case CONN_TYPE_EXT_OR: return "Extended OR";
      case CONN_TYPE_EXT_OR_LISTENER: return "Extended OR listener";
      case CONN_TYPE_AP_HTTP_CONNECT_LISTENER: return "HTTP tunnel listener";
      default:
        log_warn(LD_BUG, "unknown connection type %d", type);
        tor_snprintf(buf, sizeof(buf), "unknown [%d]", type);
        return buf;
    }
  }
  
  /**
   * Return the human-readable name for the connection state <b>state</b>
   * for the connection type <b>type</b>
   */
  const char *
  conn_state_to_string(int type, int state)
  {
    static char buf[96];
    switch (type) {
      CASE_ANY_LISTENER_TYPE:
        if (state == LISTENER_STATE_READY)
          return "ready";
        break;
      case CONN_TYPE_OR:
        switch (state) {
          case OR_CONN_STATE_CONNECTING: return "connect()ing";
          case OR_CONN_STATE_PROXY_HANDSHAKING: return "handshaking (proxy)";
          case OR_CONN_STATE_TLS_HANDSHAKING: return "handshaking (TLS)";
          case OR_CONN_STATE_TLS_CLIENT_RENEGOTIATING:
            return "renegotiating (TLS, v2 handshake)";
          case OR_CONN_STATE_TLS_SERVER_RENEGOTIATING:
            return "waiting for renegotiation or V3 handshake";
          case OR_CONN_STATE_OR_HANDSHAKING_V2:
            return "handshaking (Tor, v2 handshake)";
          case OR_CONN_STATE_OR_HANDSHAKING_V3:
            return "handshaking (Tor, v3 handshake)";
          case OR_CONN_STATE_OPEN: return "open";
        }
        break;
      case CONN_TYPE_EXT_OR:
        switch (state) {
          case EXT_OR_CONN_STATE_AUTH_WAIT_AUTH_TYPE:
            return "waiting for authentication type";
          case EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_NONCE:
            return "waiting for client nonce";
          case EXT_OR_CONN_STATE_AUTH_WAIT_CLIENT_HASH:
            return "waiting for client hash";
          case EXT_OR_CONN_STATE_OPEN: return "open";
          case EXT_OR_CONN_STATE_FLUSHING: return "flushing final OKAY";
        }
        break;
      case CONN_TYPE_EXIT:
        switch (state) {
          case EXIT_CONN_STATE_RESOLVING: return "waiting for dest info";
          case EXIT_CONN_STATE_CONNECTING: return "connecting";
          case EXIT_CONN_STATE_OPEN: return "open";
          case EXIT_CONN_STATE_RESOLVEFAILED: return "resolve failed";
        }
        break;
      case CONN_TYPE_AP:
        switch (state) {
          case AP_CONN_STATE_SOCKS_WAIT: return "waiting for socks info";
          case AP_CONN_STATE_NATD_WAIT: return "waiting for natd dest info";
          case AP_CONN_STATE_RENDDESC_WAIT: return "waiting for rendezvous desc";
          case AP_CONN_STATE_CONTROLLER_WAIT: return "waiting for controller";
          case AP_CONN_STATE_CIRCUIT_WAIT: return "waiting for circuit";
          case AP_CONN_STATE_CONNECT_WAIT: return "waiting for connect response";
          case AP_CONN_STATE_RESOLVE_WAIT: return "waiting for resolve response";
          case AP_CONN_STATE_OPEN: return "open";
        }
        break;
      case CONN_TYPE_DIR:
        switch (state) {
          case DIR_CONN_STATE_CONNECTING: return "connecting";
          case DIR_CONN_STATE_CLIENT_SENDING: return "client sending";
          case DIR_CONN_STATE_CLIENT_READING: return "client reading";
          case DIR_CONN_STATE_CLIENT_FINISHED: return "client finished";
          case DIR_CONN_STATE_SERVER_COMMAND_WAIT: return "waiting for command";
          case DIR_CONN_STATE_SERVER_WRITING: return "writing";
        }
        break;
      case CONN_TYPE_CONTROL:
        switch (state) {
          case CONTROL_CONN_STATE_OPEN: return "open (protocol v1)";
          case CONTROL_CONN_STATE_NEEDAUTH:
            return "waiting for authentication (protocol v1)";
        }
        break;
    }
  
    log_warn(LD_BUG, "unknown connection state %d (type %d)", state, type);
    tor_snprintf(buf, sizeof(buf),
                 "unknown state [%d] on unknown [%s] connection",
                 state, conn_type_to_string(type));
    return buf;
  }
  
  /** Allocate and return a new dir_connection_t, initialized as by
   * connection_init(). */
  dir_connection_t *
  dir_connection_new(int socket_family)
  {
    dir_connection_t *dir_conn = tor_malloc_zero(sizeof(dir_connection_t));
    connection_init(time(NULL), TO_CONN(dir_conn), CONN_TYPE_DIR, socket_family);
    return dir_conn;
  }
  
  /** Allocate and return a new or_connection_t, initialized as by
   * connection_init().
   *
   * Initialize active_circuit_pqueue.
   *
   * Set active_circuit_pqueue_last_recalibrated to current cell_ewma tick.
   */
  or_connection_t *
  or_connection_new(int type, int socket_family)
  {
    or_connection_t *or_conn = tor_malloc_zero(sizeof(or_connection_t));
    time_t now = time(NULL);
    tor_assert(type == CONN_TYPE_OR || type == CONN_TYPE_EXT_OR);
    connection_init(now, TO_CONN(or_conn), type, socket_family);
  
    connection_or_set_canonical(or_conn, 0);
  
    if (type == CONN_TYPE_EXT_OR)
      connection_or_set_ext_or_identifier(or_conn);
  
    return or_conn;
  }
  
  /** Allocate and return a new entry_connection_t, initialized as by
   * connection_init().
   *
   * Allocate space to store the socks_request.
   */
  entry_connection_t *
  entry_connection_new(int type, int socket_family)
  {
    entry_connection_t *entry_conn = tor_malloc_zero(sizeof(entry_connection_t));
    tor_assert(type == CONN_TYPE_AP);
    connection_init(time(NULL), ENTRY_TO_CONN(entry_conn), type, socket_family);
    entry_conn->socks_request = socks_request_new();
    /* If this is coming from a listener, we'll set it up based on the listener
     * in a little while.  Otherwise, we're doing this as a linked connection
     * of some kind, and we should set it up here based on the socket family */
    if (socket_family == AF_INET)
      entry_conn->entry_cfg.ipv4_traffic = 1;
    else if (socket_family == AF_INET6)
      entry_conn->entry_cfg.ipv6_traffic = 1;
    return entry_conn;
  }
  
  /** Allocate and return a new edge_connection_t, initialized as by
   * connection_init(). */
  edge_connection_t *
  edge_connection_new(int type, int socket_family)
  {
    edge_connection_t *edge_conn = tor_malloc_zero(sizeof(edge_connection_t));
    tor_assert(type == CONN_TYPE_EXIT);
    connection_init(time(NULL), TO_CONN(edge_conn), type, socket_family);
    return edge_conn;
  }
  
  /** Allocate and return a new control_connection_t, initialized as by
   * connection_init(). */
  control_connection_t *
  control_connection_new(int socket_family)
  {
    control_connection_t *control_conn =
      tor_malloc_zero(sizeof(control_connection_t));
    connection_init(time(NULL),
                    TO_CONN(control_conn), CONN_TYPE_CONTROL, socket_family);
    return control_conn;
  }
  
  /** Allocate and return a new listener_connection_t, initialized as by
   * connection_init(). */
  listener_connection_t *
  listener_connection_new(int type, int socket_family)
  {
    listener_connection_t *listener_conn =
      tor_malloc_zero(sizeof(listener_connection_t));
    connection_init(time(NULL), TO_CONN(listener_conn), type, socket_family);
    return listener_conn;
  }
  
  /** Allocate, initialize, and return a new connection_t subtype of <b>type</b>
   * to make or receive connections of address family <b>socket_family</b>.  The
   * type should be one of the CONN_TYPE_* constants. */
  connection_t *
  connection_new(int type, int socket_family)
  {
    switch (type) {
      case CONN_TYPE_OR:
      case CONN_TYPE_EXT_OR:
        return TO_CONN(or_connection_new(type, socket_family));
  
      case CONN_TYPE_EXIT:
        return TO_CONN(edge_connection_new(type, socket_family));
  
      case CONN_TYPE_AP:
        return ENTRY_TO_CONN(entry_connection_new(type, socket_family));
  
      case CONN_TYPE_DIR:
        return TO_CONN(dir_connection_new(socket_family));
  
      case CONN_TYPE_CONTROL:
        return TO_CONN(control_connection_new(socket_family));
  
      CASE_ANY_LISTENER_TYPE:
        return TO_CONN(listener_connection_new(type, socket_family));
  
      default: {
        connection_t *conn = tor_malloc_zero(sizeof(connection_t));
        connection_init(time(NULL), conn, type, socket_family);
        return conn;
      }
    }
  }
  
  /** Initializes conn. (you must call connection_add() to link it into the main
   * array).
   *
   * Set conn-\>magic to the correct value.
   *
   * Set conn-\>type to <b>type</b>. Set conn-\>s and conn-\>conn_array_index to
   * -1 to signify they are not yet assigned.
   *
   * Initialize conn's timestamps to now.
   */
  static void
  connection_init(time_t now, connection_t *conn, int type, int socket_family)
  {
    static uint64_t n_connections_allocated = 1;
  
    switch (type) {
      case CONN_TYPE_OR:
      case CONN_TYPE_EXT_OR:
        conn->magic = OR_CONNECTION_MAGIC;
        break;
      case CONN_TYPE_EXIT:
        conn->magic = EDGE_CONNECTION_MAGIC;
        break;
      case CONN_TYPE_AP:
        conn->magic = ENTRY_CONNECTION_MAGIC;
        break;
      case CONN_TYPE_DIR:
        conn->magic = DIR_CONNECTION_MAGIC;
        break;
      case CONN_TYPE_CONTROL:
        conn->magic = CONTROL_CONNECTION_MAGIC;
        break;
      CASE_ANY_LISTENER_TYPE:
        conn->magic = LISTENER_CONNECTION_MAGIC;
        break;
      default:
        conn->magic = BASE_CONNECTION_MAGIC;
        break;
    }
  
    conn->s = TOR_INVALID_SOCKET; /* give it a default of 'not used' */
    conn->conn_array_index = -1; /* also default to 'not used' */
    conn->global_identifier = n_connections_allocated++;
  
    conn->type = type;
    conn->socket_family = socket_family;
    if (!connection_is_listener(conn)) {
      /* listeners never use their buf */
      conn->inbuf = buf_new();
      conn->outbuf = buf_new();
    }
  
    conn->timestamp_created = now;
    conn->timestamp_last_read_allowed = now;
    conn->timestamp_last_write_allowed = now;
  }
  
  /** Create a link between <b>conn_a</b> and <b>conn_b</b>. */
  void
  connection_link_connections(connection_t *conn_a, connection_t *conn_b)
  {
    tor_assert(! SOCKET_OK(conn_a->s));
    tor_assert(! SOCKET_OK(conn_b->s));
  
    conn_a->linked = 1;
    conn_b->linked = 1;
    conn_a->linked_conn = conn_b;
    conn_b->linked_conn = conn_a;
  }
  
  /** Return true iff the provided connection listener type supports AF_UNIX
   * sockets. */
  int
  conn_listener_type_supports_af_unix(int type)
  {
    /* For now only control ports or SOCKS ports can be Unix domain sockets
     * and listeners at the same time */
    switch (type) {
      case CONN_TYPE_CONTROL_LISTENER:
      case CONN_TYPE_AP_LISTENER:
        return 1;
      default:
        return 0;
    }
  }
  
  /** Deallocate memory used by <b>conn</b>. Deallocate its buffers if
   * necessary, close its socket if necessary, and mark the directory as dirty
   * if <b>conn</b> is an OR or OP connection.
   */
  STATIC void
  connection_free_minimal(connection_t *conn)
  {
    void *mem;
    size_t memlen;
    if (!conn)
      return;
  
    switch (conn->type) {
      case CONN_TYPE_OR:
      case CONN_TYPE_EXT_OR:
        tor_assert(conn->magic == OR_CONNECTION_MAGIC);
        mem = TO_OR_CONN(conn);
        memlen = sizeof(or_connection_t);
        break;
      case CONN_TYPE_AP:
        tor_assert(conn->magic == ENTRY_CONNECTION_MAGIC);
        mem = TO_ENTRY_CONN(conn);
        memlen = sizeof(entry_connection_t);
        break;
      case CONN_TYPE_EXIT:
        tor_assert(conn->magic == EDGE_CONNECTION_MAGIC);
        mem = TO_EDGE_CONN(conn);
        memlen = sizeof(edge_connection_t);
        break;
      case CONN_TYPE_DIR:
        tor_assert(conn->magic == DIR_CONNECTION_MAGIC);
        mem = TO_DIR_CONN(conn);
        memlen = sizeof(dir_connection_t);
        break;
      case CONN_TYPE_CONTROL:
        tor_assert(conn->magic == CONTROL_CONNECTION_MAGIC);
        mem = TO_CONTROL_CONN(conn);
        memlen = sizeof(control_connection_t);
        break;
      CASE_ANY_LISTENER_TYPE:
        tor_assert(conn->magic == LISTENER_CONNECTION_MAGIC);
        mem = TO_LISTENER_CONN(conn);
        memlen = sizeof(listener_connection_t);
        break;
      default:
        tor_assert(conn->magic == BASE_CONNECTION_MAGIC);
        mem = conn;
        memlen = sizeof(connection_t);
        break;
    }
  
    if (conn->linked) {
      log_info(LD_GENERAL, "Freeing linked %s connection [%s] with %d "
               "bytes on inbuf, %d on outbuf.",
               conn_type_to_string(conn->type),
               conn_state_to_string(conn->type, conn->state),
               (int)connection_get_inbuf_len(conn),
               (int)connection_get_outbuf_len(conn));
    }
  
    if (!connection_is_listener(conn)) {
      buf_free(conn->inbuf);
      buf_free(conn->outbuf);
    } else {
      if (conn->socket_family == AF_UNIX) {
        /* For now only control and SOCKS ports can be Unix domain sockets
         * and listeners at the same time */
        tor_assert(conn_listener_type_supports_af_unix(conn->type));
  
        if (unlink(conn->address) < 0 && errno != ENOENT) {
          log_warn(LD_NET, "Could not unlink %s: %s", conn->address,
                           strerror(errno));
        }
      }
    }
  
    tor_free(conn->address);
  
    if (connection_speaks_cells(conn)) {
      or_connection_t *or_conn = TO_OR_CONN(conn);
      if (or_conn->tls) {
        if (! SOCKET_OK(conn->s)) {
          /* The socket has been closed by somebody else; we must tell the
           * TLS object not to close it. */
          tor_tls_release_socket(or_conn->tls);
        } else {
          /* The tor_tls_free() call below will close the socket; we must tell
           * the code below not to close it a second time. */
          tor_release_socket_ownership(conn->s);
          conn->s = TOR_INVALID_SOCKET;
        }
        tor_tls_free(or_conn->tls);
        or_conn->tls = NULL;
      }
      or_handshake_state_free(or_conn->handshake_state);
      or_conn->handshake_state = NULL;
      tor_free(or_conn->nickname);
      if (or_conn->chan) {
        /* Owww, this shouldn't happen, but... */
        channel_t *base_chan = TLS_CHAN_TO_BASE(or_conn->chan);
        tor_assert(base_chan);
        log_info(LD_CHANNEL,
                 "Freeing orconn at %p, saw channel %p with ID "
                 "%"PRIu64 " left un-NULLed",
                 or_conn, base_chan,
                 base_chan->global_identifier);
        if (!CHANNEL_FINISHED(base_chan)) {
          channel_close_for_error(base_chan);
        }
  
        or_conn->chan->conn = NULL;
        or_conn->chan = NULL;
      }
    }
    if (conn->type == CONN_TYPE_AP) {
      entry_connection_t *entry_conn = TO_ENTRY_CONN(conn);
      tor_free(entry_conn->chosen_exit_name);
      tor_free(entry_conn->original_dest_address);
      if (entry_conn->socks_request)
        socks_request_free(entry_conn->socks_request);
      if (entry_conn->pending_optimistic_data) {
        buf_free(entry_conn->pending_optimistic_data);
      }
      if (entry_conn->sending_optimistic_data) {
        buf_free(entry_conn->sending_optimistic_data);
      }
    }
    if (CONN_IS_EDGE(conn)) {
      rend_data_free(TO_EDGE_CONN(conn)->rend_data);
      hs_ident_edge_conn_free(TO_EDGE_CONN(conn)->hs_ident);
    }
    if (conn->type == CONN_TYPE_CONTROL) {
      control_connection_t *control_conn = TO_CONTROL_CONN(conn);
      tor_free(control_conn->safecookie_client_hash);
      tor_free(control_conn->incoming_cmd);
      if (control_conn->ephemeral_onion_services) {
        SMARTLIST_FOREACH(control_conn->ephemeral_onion_services, char *, cp, {
          memwipe(cp, 0, strlen(cp));
          tor_free(cp);
        });
        smartlist_free(control_conn->ephemeral_onion_services);
      }
    }
  
    /* Probably already freed by connection_free. */
    tor_event_free(conn->read_event);
    tor_event_free(conn->write_event);
    conn->read_event = conn->write_event = NULL;
  
    if (conn->type == CONN_TYPE_DIR) {
      dir_connection_t *dir_conn = TO_DIR_CONN(conn);
      tor_free(dir_conn->requested_resource);
  
      tor_compress_free(dir_conn->compress_state);
      if (dir_conn->spool) {
        SMARTLIST_FOREACH(dir_conn->spool, spooled_resource_t *, spooled,
                          spooled_resource_free(spooled));
        smartlist_free(dir_conn->spool);
      }
  
      rend_data_free(dir_conn->rend_data);
      hs_ident_dir_conn_free(dir_conn->hs_ident);
      if (dir_conn->guard_state) {
        /* Cancel before freeing, if it's still there. */
        entry_guard_cancel(&dir_conn->guard_state);
      }
      circuit_guard_state_free(dir_conn->guard_state);
    }
  
    if (SOCKET_OK(conn->s)) {
      log_debug(LD_NET,"closing fd %d.",(int)conn->s);
      tor_close_socket(conn->s);
      conn->s = TOR_INVALID_SOCKET;
    }
  
    if (conn->type == CONN_TYPE_OR &&
        !tor_digest_is_zero(TO_OR_CONN(conn)->identity_digest)) {
      log_warn(LD_BUG, "called on OR conn with non-zeroed identity_digest");
      connection_or_clear_identity(TO_OR_CONN(conn));
    }
    if (conn->type == CONN_TYPE_OR || conn->type == CONN_TYPE_EXT_OR) {
      connection_or_remove_from_ext_or_id_map(TO_OR_CONN(conn));
      tor_free(TO_OR_CONN(conn)->ext_or_conn_id);
      tor_free(TO_OR_CONN(conn)->ext_or_auth_correct_client_hash);
      tor_free(TO_OR_CONN(conn)->ext_or_transport);
    }
  
    memwipe(mem, 0xCC, memlen); /* poison memory */
    tor_free(mem);
  }
  
  /** Make sure <b>conn</b> isn't in any of the global conn lists; then free it.
   */
  MOCK_IMPL(void,
  connection_free_,(connection_t *conn))
  {
    if (!conn)
      return;
    tor_assert(!connection_is_on_closeable_list(conn));
    tor_assert(!connection_in_array(conn));
    if (BUG(conn->linked_conn)) {
      conn->linked_conn->linked_conn = NULL;
      if (! conn->linked_conn->marked_for_close &&
          conn->linked_conn->reading_from_linked_conn)
        connection_start_reading(conn->linked_conn);
      conn->linked_conn = NULL;
    }
    if (connection_speaks_cells(conn)) {
      if (!tor_digest_is_zero(TO_OR_CONN(conn)->identity_digest)) {
        connection_or_clear_identity(TO_OR_CONN(conn));
      }
    }
    if (conn->type == CONN_TYPE_CONTROL) {
      connection_control_closed(TO_CONTROL_CONN(conn));
    }
  #if 1
    /* DEBUGGING */
    if (conn->type == CONN_TYPE_AP) {
      connection_ap_warn_and_unmark_if_pending_circ(TO_ENTRY_CONN(conn),
                                                    "connection_free");
    }
  #endif /* 1 */
  
    /* Notify the circuit creation DoS mitigation subsystem that an OR client
     * connection has been closed. And only do that if we track it. */
    if (conn->type == CONN_TYPE_OR) {
      dos_close_client_conn(TO_OR_CONN(conn));
    }
  
    connection_unregister_events(conn);
    connection_free_minimal(conn);
  }
  
  /**
   * Called when we're about to finally unlink and free a connection:
   * perform necessary accounting and cleanup
   *   - Directory conns that failed to fetch a rendezvous descriptor
   *     need to inform pending rendezvous streams.
   *   - OR conns need to call rep_hist_note_*() to record status.
   *   - AP conns need to send a socks reject if necessary.
   *   - Exit conns need to call connection_dns_remove() if necessary.
   *   - AP and Exit conns need to send an end cell if they can.
   *   - DNS conns need to fail any resolves that are pending on them.
   *   - OR and edge connections need to be unlinked from circuits.
   */
  void
  connection_about_to_close_connection(connection_t *conn)
  {
    tor_assert(conn->marked_for_close);
  
    switch (conn->type) {
      case CONN_TYPE_DIR:
        connection_dir_about_to_close(TO_DIR_CONN(conn));
        break;
      case CONN_TYPE_OR:
      case CONN_TYPE_EXT_OR:
        connection_or_about_to_close(TO_OR_CONN(conn));
        break;
      case CONN_TYPE_AP:
        connection_ap_about_to_close(TO_ENTRY_CONN(conn));
        break;
      case CONN_TYPE_EXIT:
        connection_exit_about_to_close(TO_EDGE_CONN(conn));
        break;
    }
  }
  
  /** Return true iff connection_close_immediate() has been called on this
   * connection. */
  #define CONN_IS_CLOSED(c) \
    ((c)->linked ? ((c)->linked_conn_is_closed) : (! SOCKET_OK(c->s)))
  
  /** Close the underlying socket for <b>conn</b>, so we don't try to
   * flush it. Must be used in conjunction with (right before)
   * connection_mark_for_close().
   */
  void
  connection_close_immediate(connection_t *conn)
  {
    assert_connection_ok(conn,0);
    if (CONN_IS_CLOSED(conn)) {
      log_err(LD_BUG,"Attempt to close already-closed connection.");
      tor_fragile_assert();
      return;
    }
    if (conn->outbuf_flushlen) {
      log_info(LD_NET,"fd %d, type %s, state %s, %d bytes on outbuf.",
               (int)conn->s, conn_type_to_string(conn->type),
               conn_state_to_string(conn->type, conn->state),
               (int)conn->outbuf_flushlen);
    }
  
    connection_unregister_events(conn);
  
    /* Prevent the event from getting unblocked. */
    conn->read_blocked_on_bw = 0;
    conn->write_blocked_on_bw = 0;
  
    if (SOCKET_OK(conn->s))
      tor_close_socket(conn->s);
    conn->s = TOR_INVALID_SOCKET;
    if (conn->linked)
      conn->linked_conn_is_closed = 1;
    if (conn->outbuf)
      buf_clear(conn->outbuf);
    conn->outbuf_flushlen = 0;
  }
  
  /** Mark <b>conn</b> to be closed next time we loop through
   * conn_close_if_marked() in main.c. */
  void
  connection_mark_for_close_(connection_t *conn, int line, const char *file)
  {
    assert_connection_ok(conn,0);
    tor_assert(line);
    tor_assert(line < 1<<16); /* marked_for_close can only fit a uint16_t. */
    tor_assert(file);
  
    if (conn->type == CONN_TYPE_OR) {
      /*
       * An or_connection should have been closed through one of the channel-
       * aware functions in connection_or.c.  We'll assume this is an error
       * close and do that, and log a bug warning.
       */
      log_warn(LD_CHANNEL | LD_BUG,
               "Something tried to close an or_connection_t without going "
               "through channels at %s:%d",
               file, line);
      connection_or_close_for_error(TO_OR_CONN(conn), 0);
    } else {
      /* Pass it down to the real function */
      connection_mark_for_close_internal_(conn, line, file);
    }
  }
  
  /** Mark <b>conn</b> to be closed next time we loop through
   * conn_close_if_marked() in main.c.
   *
   * This _internal version bypasses the CONN_TYPE_OR checks; this should be
   * called when you either are sure that if this is an or_connection_t the
   * controlling channel has been notified (e.g. with
   * connection_or_notify_error()), or you actually are the
   * connection_or_close_for_error() or connection_or_close_normally() function.
   * For all other cases, use connection_mark_and_flush() which checks for
   * or_connection_t properly, instead.  See below.
   *
   * We want to keep this function simple and quick, since it can be called from
   * quite deep in the call chain, and hence it should avoid having side-effects
   * that interfere with its callers view of the connection.
   */
  MOCK_IMPL(void,
  connection_mark_for_close_internal_, (connection_t *conn,
                                        int line, const char *file))
  {
    assert_connection_ok(conn,0);
    tor_assert(line);
    tor_assert(line < 1<<16); /* marked_for_close can only fit a uint16_t. */
    tor_assert(file);
  
    if (conn->marked_for_close) {
      log_warn(LD_BUG,"Duplicate call to connection_mark_for_close at %s:%d"
          " (first at %s:%d)", file, line, conn->marked_for_close_file,
          conn->marked_for_close);
      tor_fragile_assert();
      return;
    }
  
    if (conn->type == CONN_TYPE_OR) {
      /*
       * Bad news if this happens without telling the controlling channel; do
       * this so we can find things that call this wrongly when the asserts hit.
       */
      log_debug(LD_CHANNEL,
                "Calling connection_mark_for_close_internal_() on an OR conn "
                "at %s:%d",
                file, line);
    }
  
    conn->marked_for_close = line;
    conn->marked_for_close_file = file;
    add_connection_to_closeable_list(conn);
  
    /* in case we're going to be held-open-til-flushed, reset
     * the number of seconds since last successful write, so
     * we get our whole 15 seconds */
    conn->timestamp_last_write_allowed = time(NULL);
  }
  
  /** Find each connection that has hold_open_until_flushed set to
   * 1 but hasn't written in the past 15 seconds, and set
   * hold_open_until_flushed to 0. This means it will get cleaned
   * up in the next loop through close_if_marked() in main.c.
   */
  void
  connection_expire_held_open(void)
  {
    time_t now;
    smartlist_t *conns = get_connection_array();
  
    now = time(NULL);
  
    SMARTLIST_FOREACH_BEGIN(conns, connection_t *, conn) {
      /* If we've been holding the connection open, but we haven't written
       * for 15 seconds...
       */
      if (conn->hold_open_until_flushed) {
        tor_assert(conn->marked_for_close);
        if (now - conn->timestamp_last_write_allowed >= 15) {
          int severity;
          if (conn->type == CONN_TYPE_EXIT ||
              (conn->type == CONN_TYPE_DIR &&
               conn->purpose == DIR_PURPOSE_SERVER))
            severity = LOG_INFO;
          else
            severity = LOG_NOTICE;
          log_fn(severity, LD_NET,
                 "Giving up on marked_for_close conn that's been flushing "
                 "for 15s (fd %d, type %s, state %s).",
                 (int)conn->s, conn_type_to_string(conn->type),
                 conn_state_to_string(conn->type, conn->state));
          conn->hold_open_until_flushed = 0;
        }
      }
    } SMARTLIST_FOREACH_END(conn);
  }
  
  #if defined(HAVE_SYS_UN_H) || defined(RUNNING_DOXYGEN)
  /** Create an AF_UNIX listenaddr struct.
   * <b>listenaddress</b> provides the path to the Unix socket.
   *
   * Eventually <b>listenaddress</b> will also optionally contain user, group,
   * and file permissions for the new socket.  But not yet. XXX
   * Also, since we do not create the socket here the information doesn't help
   * here.
   *
   * If not NULL <b>readable_address</b> will contain a copy of the path part of
   * <b>listenaddress</b>.
   *
   * The listenaddr struct has to be freed by the caller.
   */
  static struct sockaddr_un *
  create_unix_sockaddr(const char *listenaddress, char **readable_address,
                       socklen_t *len_out)
  {
    struct sockaddr_un *sockaddr = NULL;
  
    sockaddr = tor_malloc_zero(sizeof(struct sockaddr_un));
    sockaddr->sun_family = AF_UNIX;
    if (strlcpy(sockaddr->sun_path, listenaddress, sizeof(sockaddr->sun_path))
        >= sizeof(sockaddr->sun_path)) {
      log_warn(LD_CONFIG, "Unix socket path '%s' is too long to fit.",
               escaped(listenaddress));
      tor_free(sockaddr);
      return NULL;
    }
  
    if (readable_address)
      *readable_address = tor_strdup(listenaddress);
  
    *len_out = sizeof(struct sockaddr_un);
    return sockaddr;
  }
  #else /* !(defined(HAVE_SYS_UN_H) || defined(RUNNING_DOXYGEN)) */
  static struct sockaddr *
  create_unix_sockaddr(const char *listenaddress, char **readable_address,
                       socklen_t *len_out)
  {
    (void)listenaddress;
    (void)readable_address;
    log_fn(LOG_ERR, LD_BUG,
           "Unix domain sockets not supported, yet we tried to create one.");
    *len_out = 0;
    tor_fragile_assert();
    return NULL;
  }
  #endif /* defined(HAVE_SYS_UN_H) || defined(RUNNING_DOXYGEN) */
  
  /** Warn that an accept or a connect has failed because we're running out of
   * TCP sockets we can use on current system.  Rate-limit these warnings so
   * that we don't spam the log. */
  static void
  warn_too_many_conns(void)
  {
  #define WARN_TOO_MANY_CONNS_INTERVAL (6*60*60)
    static ratelim_t last_warned = RATELIM_INIT(WARN_TOO_MANY_CONNS_INTERVAL);
    char *m;
    if ((m = rate_limit_log(&last_warned, approx_time()))) {
      int n_conns = get_n_open_sockets();
      log_warn(LD_NET,"Failing because we have %d connections already. Please "
               "read doc/TUNING for guidance.%s", n_conns, m);
      tor_free(m);
      control_event_general_status(LOG_WARN, "TOO_MANY_CONNECTIONS CURRENT=%d",
                                   n_conns);
    }
  }
  
  #ifdef HAVE_SYS_UN_H
  
  #define UNIX_SOCKET_PURPOSE_CONTROL_SOCKET 0
  #define UNIX_SOCKET_PURPOSE_SOCKS_SOCKET 1
  
  /** Check if the purpose isn't one of the ones we know what to do with */
  
  static int
  is_valid_unix_socket_purpose(int purpose)
  {
    int valid = 0;
  
    switch (purpose) {
      case UNIX_SOCKET_PURPOSE_CONTROL_SOCKET:
      case UNIX_SOCKET_PURPOSE_SOCKS_SOCKET:
        valid = 1;
        break;
    }
  
    return valid;
  }
  
  /** Return a string description of a unix socket purpose */
  static const char *
  unix_socket_purpose_to_string(int purpose)
  {
    const char *s = "unknown-purpose socket";
  
    switch (purpose) {
      case UNIX_SOCKET_PURPOSE_CONTROL_SOCKET:
        s = "control socket";
        break;
      case UNIX_SOCKET_PURPOSE_SOCKS_SOCKET:
        s = "SOCKS socket";
        break;
    }
  
    return s;
  }
  
  /** Check whether we should be willing to open an AF_UNIX socket in
   * <b>path</b>.  Return 0 if we should go ahead and -1 if we shouldn't. */
  static int
  check_location_for_unix_socket(const or_options_t *options, const char *path,
                                 int purpose, const port_cfg_t *port)
  {
    int r = -1;
    char *p = NULL;
  
    tor_assert(is_valid_unix_socket_purpose(purpose));
  
    p = tor_strdup(path);
    cpd_check_t flags = CPD_CHECK_MODE_ONLY;
    if (get_parent_directory(p)<0 || p[0] != '/') {
      log_warn(LD_GENERAL, "Bad unix socket address '%s'.  Tor does not support "
               "relative paths for unix sockets.", path);
      goto done;
    }
  
    if (port->is_world_writable) {
      /* World-writable sockets can go anywhere. */
      r = 0;
      goto done;
    }
  
    if (port->is_group_writable) {
      flags |= CPD_GROUP_OK;
    }
  
    if (port->relax_dirmode_check) {
      flags |= CPD_RELAX_DIRMODE_CHECK;
    }
  
    if (check_private_dir(p, flags, options->User) < 0) {
      char *escpath, *escdir;
      escpath = esc_for_log(path);
      escdir = esc_for_log(p);
      log_warn(LD_GENERAL, "Before Tor can create a %s in %s, the directory "
               "%s needs to exist, and to be accessible only by the user%s "
               "account that is running Tor.  (On some Unix systems, anybody "
               "who can list a socket can connect to it, so Tor is being "
               "careful.)",
               unix_socket_purpose_to_string(purpose), escpath, escdir,
               port->is_group_writable ? " and group" : "");
      tor_free(escpath);
      tor_free(escdir);
      goto done;
    }
  
    r = 0;
   done:
    tor_free(p);
    return r;
  }
  #endif /* defined(HAVE_SYS_UN_H) */
  
  /** Tell the TCP stack that it shouldn't wait for a long time after
   * <b>sock</b> has closed before reusing its port. Return 0 on success,
   * -1 on failure. */
  static int
  make_socket_reuseable(tor_socket_t sock)
  {
  #ifdef _WIN32
    (void) sock;
    return 0;
  #else
    int one=1;
  
    /* REUSEADDR on normal places means you can rebind to the port
     * right after somebody else has let it go. But REUSEADDR on win32
     * means you can bind to the port _even when somebody else
     * already has it bound_. So, don't do that on Win32. */
    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void*) &one,
               (socklen_t)sizeof(one)) == -1) {
      return -1;
    }
    return 0;
  #endif /* defined(_WIN32) */
  }
  
  #ifdef _WIN32
  /** Tell the Windows TCP stack to prevent other applications from receiving
   * traffic from tor's open ports. Return 0 on success, -1 on failure. */
  static int
  make_win32_socket_exclusive(tor_socket_t sock)
  {
  #ifdef SO_EXCLUSIVEADDRUSE
    int one=1;
  
    /* Any socket that sets REUSEADDR on win32 can bind to a port _even when
     * somebody else already has it bound_, and _even if the original socket
     * didn't set REUSEADDR_. Use EXCLUSIVEADDRUSE to prevent this port-stealing
     * on win32. */
    if (setsockopt(sock, SOL_SOCKET, SO_EXCLUSIVEADDRUSE, (void*) &one,
                   (socklen_t)sizeof(one))) {
      return -1;
    }
    return 0;
  #else /* !(defined(SO_EXCLUSIVEADDRUSE)) */
    (void) sock;
    return 0;
  #endif /* defined(SO_EXCLUSIVEADDRUSE) */
  }
  #endif /* defined(_WIN32) */
  
  /** Max backlog to pass to listen.  We start at */
  static int listen_limit = INT_MAX;
  
  /* Listen on <b>fd</b> with appropriate backlog. Return as for listen. */
  static int
  tor_listen(tor_socket_t fd)
  {
    int r;
  
    if ((r = listen(fd, listen_limit)) < 0) {
      if (listen_limit == SOMAXCONN)
        return r;
      if ((r = listen(fd, SOMAXCONN)) == 0) {
        listen_limit = SOMAXCONN;
        log_warn(LD_NET, "Setting listen backlog to INT_MAX connections "
                 "didn't work, but SOMAXCONN did. Lowering backlog limit.");
      }
    }
    return r;
  }
  
  /** Bind a new non-blocking socket listening to the socket described
   * by <b>listensockaddr</b>.
   *
   * <b>address</b> is only used for logging purposes and to add the information
   * to the conn.
   *
   * Set <b>addr_in_use</b> to true in case socket binding fails with
   * EADDRINUSE.
   */
  static connection_t *
  connection_listener_new(const struct sockaddr *listensockaddr,
                          socklen_t socklen,
                          int type, const char *address,
                          const port_cfg_t *port_cfg,
                          int *addr_in_use)
  {
    listener_connection_t *lis_conn;
    connection_t *conn = NULL;
    tor_socket_t s = TOR_INVALID_SOCKET;  /* the socket we're going to make */
    or_options_t const *options = get_options();
    (void) options; /* Windows doesn't use this. */
  #if defined(HAVE_PWD_H) && defined(HAVE_SYS_UN_H)
    const struct passwd *pw = NULL;
  #endif
    uint16_t usePort = 0, gotPort = 0;
    int start_reading = 0;
    static int global_next_session_group = SESSION_GROUP_FIRST_AUTO;
    tor_addr_t addr;
    int exhaustion = 0;
  
    if (addr_in_use)
      *addr_in_use = 0;
  
    if (listensockaddr->sa_family == AF_INET ||
        listensockaddr->sa_family == AF_INET6) {
      int is_stream = (type != CONN_TYPE_AP_DNS_LISTENER);
      if (is_stream)
        start_reading = 1;
  
      tor_addr_from_sockaddr(&addr, listensockaddr, &usePort);
      log_notice(LD_NET, "Opening %s on %s",
                 conn_type_to_string(type), fmt_addrport(&addr, usePort));
  
      s = tor_open_socket_nonblocking(tor_addr_family(&addr),
        is_stream ? SOCK_STREAM : SOCK_DGRAM,
        is_stream ? IPPROTO_TCP: IPPROTO_UDP);
      if (!SOCKET_OK(s)) {
        int e = tor_socket_errno(s);
        if (ERRNO_IS_RESOURCE_LIMIT(e)) {
          warn_too_many_conns();
          /*
           * We'll call the OOS handler at the error exit, so set the
           * exhaustion flag for it.
           */
          exhaustion = 1;
        } else {
          log_warn(LD_NET, "Socket creation failed: %s",
                   tor_socket_strerror(e));
        }
        goto err;
      }
  
      if (make_socket_reuseable(s) < 0) {
        log_warn(LD_NET, "Error setting SO_REUSEADDR flag on %s: %s",
                 conn_type_to_string(type),
                 tor_socket_strerror(errno));
      }
  
  #ifdef _WIN32
      if (make_win32_socket_exclusive(s) < 0) {
        log_warn(LD_NET, "Error setting SO_EXCLUSIVEADDRUSE flag on %s: %s",
                 conn_type_to_string(type),
                 tor_socket_strerror(errno));
      }
  #endif /* defined(_WIN32) */
  
  #if defined(USE_TRANSPARENT) && defined(IP_TRANSPARENT)
      if (options->TransProxyType_parsed == TPT_TPROXY &&
          type == CONN_TYPE_AP_TRANS_LISTENER) {
        int one = 1;
        if (setsockopt(s, SOL_IP, IP_TRANSPARENT, (void*)&one,
                       (socklen_t)sizeof(one)) < 0) {
          const char *extra = "";
          int e = tor_socket_errno(s);
          if (e == EPERM)
            extra = "TransTPROXY requires root privileges or similar"
              " capabilities.";
          log_warn(LD_NET, "Error setting IP_TRANSPARENT flag: %s.%s",
                   tor_socket_strerror(e), extra);
        }
      }
  #endif /* defined(USE_TRANSPARENT) && defined(IP_TRANSPARENT) */
  
  #ifdef IPV6_V6ONLY
      if (listensockaddr->sa_family == AF_INET6) {
        int one = 1;
        /* We need to set IPV6_V6ONLY so that this socket can't get used for
         * IPv4 connections. */
        if (setsockopt(s,IPPROTO_IPV6, IPV6_V6ONLY,
                       (void*)&one, (socklen_t)sizeof(one)) < 0) {
          int e = tor_socket_errno(s);
          log_warn(LD_NET, "Error setting IPV6_V6ONLY flag: %s",
                   tor_socket_strerror(e));
          /* Keep going; probably not harmful. */
        }
      }
  #endif /* defined(IPV6_V6ONLY) */
  
      if (bind(s,listensockaddr,socklen) < 0) {
        const char *helpfulhint = "";
        int e = tor_socket_errno(s);
        if (ERRNO_IS_EADDRINUSE(e)) {
          helpfulhint = ". Is Tor already running?";
          if (addr_in_use)
            *addr_in_use = 1;
        }
        log_warn(LD_NET, "Could not bind to %s:%u: %s%s", address, usePort,
                 tor_socket_strerror(e), helpfulhint);
        goto err;
      }
  
      if (is_stream) {
        if (tor_listen(s) < 0) {
          log_warn(LD_NET, "Could not listen on %s:%u: %s", address, usePort,
                   tor_socket_strerror(tor_socket_errno(s)));
          goto err;
        }
      }
  
      if (usePort != 0) {
        gotPort = usePort;
      } else {
        tor_addr_t addr2;
        struct sockaddr_storage ss;
        socklen_t ss_len=sizeof(ss);
        if (getsockname(s, (struct sockaddr*)&ss, &ss_len)<0) {
          log_warn(LD_NET, "getsockname() couldn't learn address for %s: %s",
                   conn_type_to_string(type),
                   tor_socket_strerror(tor_socket_errno(s)));
          gotPort = 0;
        }
        tor_addr_from_sockaddr(&addr2, (struct sockaddr*)&ss, &gotPort);
      }
  #ifdef HAVE_SYS_UN_H
    /*
     * AF_UNIX generic setup stuff
     */
    } else if (listensockaddr->sa_family == AF_UNIX) {
      /* We want to start reading for both AF_UNIX cases */
      start_reading = 1;
  
      tor_assert(conn_listener_type_supports_af_unix(type));
  
      if (check_location_for_unix_socket(options, address,
            (type == CONN_TYPE_CONTROL_LISTENER) ?
             UNIX_SOCKET_PURPOSE_CONTROL_SOCKET :
             UNIX_SOCKET_PURPOSE_SOCKS_SOCKET, port_cfg) < 0) {
          goto err;
      }
  
      log_notice(LD_NET, "Opening %s on %s",
                 conn_type_to_string(type), address);
  
      tor_addr_make_unspec(&addr);
  
      if (unlink(address) < 0 && errno != ENOENT) {
        log_warn(LD_NET, "Could not unlink %s: %s", address,
                         strerror(errno));
        goto err;
      }
  
      s = tor_open_socket_nonblocking(AF_UNIX, SOCK_STREAM, 0);
      if (! SOCKET_OK(s)) {
        int e = tor_socket_errno(s);
        if (ERRNO_IS_RESOURCE_LIMIT(e)) {
          warn_too_many_conns();
          /*
           * We'll call the OOS handler at the error exit, so set the
           * exhaustion flag for it.
           */
          exhaustion = 1;
        } else {
          log_warn(LD_NET,"Socket creation failed: %s.", strerror(e));
        }
        goto err;
      }
  
      if (bind(s, listensockaddr,
               (socklen_t)sizeof(struct sockaddr_un)) == -1) {
        log_warn(LD_NET,"Bind to %s failed: %s.", address,
                 tor_socket_strerror(tor_socket_errno(s)));
        goto err;
      }
  
  #ifdef HAVE_PWD_H
      if (options->User) {
        pw = tor_getpwnam(options->User);
        struct stat st;
        if (pw == NULL) {
          log_warn(LD_NET,"Unable to chown() %s socket: user %s not found.",
                   address, options->User);
          goto err;
        } else if (fstat(s, &st) == 0 &&
                   st.st_uid == pw->pw_uid && st.st_gid == pw->pw_gid) {
          /* No change needed */
        } else if (chown(sandbox_intern_string(address),
                         pw->pw_uid, pw->pw_gid) < 0) {
          log_warn(LD_NET,"Unable to chown() %s socket: %s.",
                   address, strerror(errno));
          goto err;
        }
      }
  #endif /* defined(HAVE_PWD_H) */
  
      {
        unsigned mode;
        const char *status;
        struct stat st;
        if (port_cfg->is_world_writable) {
          mode = 0666;
          status = "world-writable";
        } else if (port_cfg->is_group_writable) {
          mode = 0660;
          status = "group-writable";
        } else {
          mode = 0600;
          status = "private";
        }
        /* We need to use chmod; fchmod doesn't work on sockets on all
         * platforms. */
        if (fstat(s, &st) == 0 && (st.st_mode & 0777) == mode) {
          /* no change needed */
        } else if (chmod(sandbox_intern_string(address), mode) < 0) {
          log_warn(LD_FS,"Unable to make %s %s.", address, status);
          goto err;
        }
      }
  
      if (listen(s, SOMAXCONN) < 0) {
        log_warn(LD_NET, "Could not listen on %s: %s", address,
                 tor_socket_strerror(tor_socket_errno(s)));
        goto err;
      }
  #endif /* defined(HAVE_SYS_UN_H) */
    } else {
      log_err(LD_BUG, "Got unexpected address family %d.",
              listensockaddr->sa_family);
      tor_assert(0);
    }
  
    lis_conn = listener_connection_new(type, listensockaddr->sa_family);
    conn = TO_CONN(lis_conn);
    conn->socket_family = listensockaddr->sa_family;
    conn->s = s;
    s = TOR_INVALID_SOCKET; /* Prevent double-close */
    conn->address = tor_strdup(address);
    conn->port = gotPort;
    tor_addr_copy(&conn->addr, &addr);
  
    memcpy(&lis_conn->entry_cfg, &port_cfg->entry_cfg, sizeof(entry_port_cfg_t));
  
    if (port_cfg->entry_cfg.isolation_flags) {
      lis_conn->entry_cfg.isolation_flags = port_cfg->entry_cfg.isolation_flags;
      if (port_cfg->entry_cfg.session_group >= 0) {
        lis_conn->entry_cfg.session_group = port_cfg->entry_cfg.session_group;
      } else {
        /* This can wrap after around INT_MAX listeners are opened.  But I don't
         * believe that matters, since you would need to open a ridiculous
         * number of listeners while keeping the early ones open before you ever
         * hit this.  An OR with a dozen ports open, for example, would have to
         * close and re-open its listeners every second for 4 years nonstop.
         */
        lis_conn->entry_cfg.session_group = global_next_session_group--;
      }
    }
  
    if (type != CONN_TYPE_AP_LISTENER) {
      lis_conn->entry_cfg.ipv4_traffic = 1;
      lis_conn->entry_cfg.ipv6_traffic = 1;
      lis_conn->entry_cfg.prefer_ipv6 = 0;
    }
  
    if (connection_add(conn) < 0) { /* no space, forget it */
      log_warn(LD_NET,"connection_add for listener failed. Giving up.");
      goto err;
    }
  
    log_fn(usePort==gotPort ? LOG_DEBUG : LOG_NOTICE, LD_NET,
           "%s listening on port %u.",
           conn_type_to_string(type), gotPort);
  
    conn->state = LISTENER_STATE_READY;
    if (start_reading) {
      connection_start_reading(conn);
    } else {
      tor_assert(type == CONN_TYPE_AP_DNS_LISTENER);
      dnsserv_configure_listener(conn);
    }
  
    /*
     * Normal exit; call the OOS handler since connection count just changed;
     * the exhaustion flag will always be zero here though.
     */
    connection_check_oos(get_n_open_sockets(), 0);
  
    if (conn->socket_family == AF_UNIX) {
      log_notice(LD_NET, "Opened %s on %s",
                 conn_type_to_string(type), conn->address);
    } else {
      log_notice(LD_NET, "Opened %s on %s",
                 conn_type_to_string(type), fmt_addrport(&addr, gotPort));
    }
    return conn;
  
   err:
    if (SOCKET_OK(s))
      tor_close_socket(s);
    if (conn)
      connection_free(conn);
  
    /* Call the OOS handler, indicate if we saw an exhaustion-related error */
    connection_check_oos(get_n_open_sockets(), exhaustion);
  
    return NULL;
  }
  
  /**
   * Create a new listener connection for a given <b>port</b>. In case we
   * for a reason that is not an error condition, set <b>defer</b>
   * to true. If we cannot bind listening socket because address is already
   * in use, set <b>addr_in_use</b> to true.
   */
  static connection_t *
  connection_listener_new_for_port(const port_cfg_t *port,
                                   int *defer, int *addr_in_use)
  {
    connection_t *conn;
    struct sockaddr *listensockaddr;
    socklen_t listensocklen = 0;
    char *address=NULL;
    int real_port = port->port == CFG_AUTO_PORT ? 0 : port->port;
    tor_assert(real_port <= UINT16_MAX);
  
    if (defer)
      *defer = 0;
  
    if (port->server_cfg.no_listen) {
      if (defer)
        *defer = 1;
      return NULL;
    }
  
  #ifndef _WIN32
    /* We don't need to be root to create a UNIX socket, so defer until after
     * setuid. */
    const or_options_t *options = get_options();
    if (port->is_unix_addr && !geteuid() && (options->User) &&
        strcmp(options->User, "root")) {
      if (defer)
        *defer = 1;
      return NULL;
    }
  #endif /* !defined(_WIN32) */
  
    if (port->is_unix_addr) {
      listensockaddr = (struct sockaddr *)
        create_unix_sockaddr(port->unix_addr,
                             &address, &listensocklen);
    } else {
      listensockaddr = tor_malloc(sizeof(struct sockaddr_storage));
      listensocklen = tor_addr_to_sockaddr(&port->addr,
                                           real_port,
                                           listensockaddr,
                                           sizeof(struct sockaddr_storage));
      address = tor_addr_to_str_dup(&port->addr);
    }
  
    if (listensockaddr) {
      conn = connection_listener_new(listensockaddr, listensocklen,
                                     port->type, address, port,
                                     addr_in_use);
      tor_free(listensockaddr);
      tor_free(address);
    } else {
      conn = NULL;
    }
  
    return conn;
  }
  
  /** Do basic sanity checking on a newly received socket. Return 0
   * if it looks ok, else return -1.
   *
   * Notably, some TCP stacks can erroneously have accept() return successfully
   * with socklen 0, when the client sends an RST before the accept call (as
   * nmap does).  We want to detect that, and not go on with the connection.
   */
  static int
  check_sockaddr(const struct sockaddr *sa, int len, int level)
  {
    int ok = 1;
  
    if (sa->sa_family == AF_INET) {
      struct sockaddr_in *sin=(struct sockaddr_in*)sa;
      if (len != sizeof(struct sockaddr_in)) {
        log_fn(level, LD_NET, "Length of address not as expected: %d vs %d",
               len,(int)sizeof(struct sockaddr_in));
        ok = 0;
      }
      if (sin->sin_addr.s_addr == 0 || sin->sin_port == 0) {
        log_fn(level, LD_NET,
               "Address for new connection has address/port equal to zero.");
        ok = 0;
      }
    } else if (sa->sa_family == AF_INET6) {
      struct sockaddr_in6 *sin6=(struct sockaddr_in6*)sa;
      if (len != sizeof(struct sockaddr_in6)) {
        log_fn(level, LD_NET, "Length of address not as expected: %d vs %d",
               len,(int)sizeof(struct sockaddr_in6));
        ok = 0;
      }
      if (tor_mem_is_zero((void*)sin6->sin6_addr.s6_addr, 16) ||
          sin6->sin6_port == 0) {
        log_fn(level, LD_NET,
               "Address for new connection has address/port equal to zero.");
        ok = 0;
      }
    } else if (sa->sa_family == AF_UNIX) {
      ok = 1;
    } else {
      ok = 0;
    }
    return ok ? 0 : -1;
  }
  
  /** Check whether the socket family from an accepted socket <b>got</b> is the
   * same as the one that <b>listener</b> is waiting for.  If it isn't, log
   * a useful message and return -1.  Else return 0.
   *
   * This is annoying, but can apparently happen on some Darwins. */
  static int
  check_sockaddr_family_match(sa_family_t got, connection_t *listener)
  {
    if (got != listener->socket_family) {
      log_info(LD_BUG, "A listener connection returned a socket with a "
               "mismatched family. %s for addr_family %d gave us a socket "
               "with address family %d.  Dropping.",
               conn_type_to_string(listener->type),
               (int)listener->socket_family,
               (int)got);
      return -1;
    }
    return 0;
  }
  
  /** The listener connection <b>conn</b> told poll() it wanted to read.
   * Call accept() on conn-\>s, and add the new connection if necessary.
   */
  static int
  connection_handle_listener_read(connection_t *conn, int new_type)
  {
    tor_socket_t news; /* the new socket */
    connection_t *newconn = 0;
    /* information about the remote peer when connecting to other routers */
    struct sockaddr_storage addrbuf;
    struct sockaddr *remote = (struct sockaddr*)&addrbuf;
    /* length of the remote address. Must be whatever accept() needs. */
    socklen_t remotelen = (socklen_t)sizeof(addrbuf);
    const or_options_t *options = get_options();
  
    tor_assert((size_t)remotelen >= sizeof(struct sockaddr_in));
    memset(&addrbuf, 0, sizeof(addrbuf));
  
    news = tor_accept_socket_nonblocking(conn->s,remote,&remotelen);
    if (!SOCKET_OK(news)) { /* accept() error */
      int e = tor_socket_errno(conn->s);
      if (ERRNO_IS_ACCEPT_EAGAIN(e)) {
        /*
         * they hung up before we could accept(). that's fine.
         *
         * give the OOS handler a chance to run though
         */
        connection_check_oos(get_n_open_sockets(), 0);
        return 0;
      } else if (ERRNO_IS_RESOURCE_LIMIT(e)) {
        warn_too_many_conns();
        /* Exhaustion; tell the OOS handler */
        connection_check_oos(get_n_open_sockets(), 1);
        return 0;
      }
      /* else there was a real error. */
      log_warn(LD_NET,"accept() failed: %s. Closing listener.",
               tor_socket_strerror(e));
      connection_mark_for_close(conn);
      /* Tell the OOS handler about this too */
      connection_check_oos(get_n_open_sockets(), 0);
      return -1;
    }
    log_debug(LD_NET,
              "Connection accepted on socket %d (child of fd %d).",
              (int)news,(int)conn->s);
  
    /* We accepted a new conn; run OOS handler */
    connection_check_oos(get_n_open_sockets(), 0);
  
    if (make_socket_reuseable(news) < 0) {
      if (tor_socket_errno(news) == EINVAL) {
        /* This can happen on OSX if we get a badly timed shutdown. */
        log_debug(LD_NET, "make_socket_reuseable returned EINVAL");
      } else {
        log_warn(LD_NET, "Error setting SO_REUSEADDR flag on %s: %s",
                 conn_type_to_string(new_type),
                 tor_socket_strerror(errno));
      }
      tor_close_socket(news);
      return 0;
    }
  
    if (options->ConstrainedSockets)
      set_constrained_socket_buffers(news, (int)options->ConstrainedSockSize);
  
    if (check_sockaddr_family_match(remote->sa_family, conn) < 0) {
      tor_close_socket(news);
      return 0;
    }
  
    if (conn->socket_family == AF_INET || conn->socket_family == AF_INET6 ||
       (conn->socket_family == AF_UNIX && new_type == CONN_TYPE_AP)) {
      tor_addr_t addr;
      uint16_t port;
      if (check_sockaddr(remote, remotelen, LOG_INFO)<0) {
        log_info(LD_NET,
                 "accept() returned a strange address; closing connection.");
        tor_close_socket(news);
        return 0;
      }
  
      tor_addr_from_sockaddr(&addr, remote, &port);
  
      /* process entrance policies here, before we even create the connection */
      if (new_type == CONN_TYPE_AP) {
        /* check sockspolicy to see if we should accept it */
        if (socks_policy_permits_address(&addr) == 0) {
          log_notice(LD_APP,
                     "Denying socks connection from untrusted address %s.",
                     fmt_and_decorate_addr(&addr));
          tor_close_socket(news);
          return 0;
        }
      }
      if (new_type == CONN_TYPE_DIR) {
        /* check dirpolicy to see if we should accept it */
        if (dir_policy_permits_address(&addr) == 0) {
          log_notice(LD_DIRSERV,"Denying dir connection from address %s.",
                     fmt_and_decorate_addr(&addr));
          tor_close_socket(news);
          return 0;
        }
      }
      if (new_type == CONN_TYPE_OR) {
        /* Assess with the connection DoS mitigation subsystem if this address
         * can open a new connection. */
        if (dos_conn_addr_get_defense_type(&addr) == DOS_CONN_DEFENSE_CLOSE) {
          tor_close_socket(news);
          return 0;
        }
      }
  
      newconn = connection_new(new_type, conn->socket_family);
      newconn->s = news;
  
      /* remember the remote address */
      tor_addr_copy(&newconn->addr, &addr);
      if (new_type == CONN_TYPE_AP && conn->socket_family == AF_UNIX) {
        newconn->port = 0;
        newconn->address = tor_strdup(conn->address);
      } else {
        newconn->port = port;
        newconn->address = tor_addr_to_str_dup(&addr);
      }
  
      if (new_type == CONN_TYPE_AP && conn->socket_family != AF_UNIX) {
        log_info(LD_NET, "New SOCKS connection opened from %s.",
                 fmt_and_decorate_addr(&addr));
      }
      if (new_type == CONN_TYPE_AP && conn->socket_family == AF_UNIX) {
        log_info(LD_NET, "New SOCKS AF_UNIX connection opened");
      }
      if (new_type == CONN_TYPE_CONTROL) {
        log_notice(LD_CONTROL, "New control connection opened from %s.",
                   fmt_and_decorate_addr(&addr));
      }
  
    } else if (conn->socket_family == AF_UNIX && conn->type != CONN_TYPE_AP) {
      tor_assert(conn->type == CONN_TYPE_CONTROL_LISTENER);
      tor_assert(new_type == CONN_TYPE_CONTROL);
      log_notice(LD_CONTROL, "New control connection opened.");
  
      newconn = connection_new(new_type, conn->socket_family);
      newconn->s = news;
  
      /* remember the remote address -- do we have anything sane to put here? */
      tor_addr_make_unspec(&newconn->addr);
      newconn->port = 1;
      newconn->address = tor_strdup(conn->address);
    } else {
      tor_assert(0);
    };
  
    if (connection_add(newconn) < 0) { /* no space, forget it */
      connection_free(newconn);
      return 0; /* no need to tear down the parent */
    }
  
    if (connection_init_accepted_conn(newconn, TO_LISTENER_CONN(conn)) < 0) {
      if (! newconn->marked_for_close)
        connection_mark_for_close(newconn);
      return 0;
    }
    return 0;
  }
  
  /** Initialize states for newly accepted connection <b>conn</b>.
   *
   * If conn is an OR, start the TLS handshake.
   *
   * If conn is a transparent AP, get its original destination
   * and place it in circuit_wait.
   *
   * The <b>listener</b> parameter is only used for AP connections.
   */
  int
  connection_init_accepted_conn(connection_t *conn,
                                const listener_connection_t *listener)
  {
    int rv;
  
    connection_start_reading(conn);
  
    switch (conn->type) {
      case CONN_TYPE_EXT_OR:
        /* Initiate Extended ORPort authentication. */
        return connection_ext_or_start_auth(TO_OR_CONN(conn));
      case CONN_TYPE_OR:
        control_event_or_conn_status(TO_OR_CONN(conn), OR_CONN_EVENT_NEW, 0);
        rv = connection_tls_start_handshake(TO_OR_CONN(conn), 1);
        if (rv < 0) {
          connection_or_close_for_error(TO_OR_CONN(conn), 0);
        }
        return rv;
        break;
      case CONN_TYPE_AP:
        memcpy(&TO_ENTRY_CONN(conn)->entry_cfg, &listener->entry_cfg,
               sizeof(entry_port_cfg_t));
        TO_ENTRY_CONN(conn)->nym_epoch = get_signewnym_epoch();
        TO_ENTRY_CONN(conn)->socks_request->listener_type = listener->base_.type;
  
        switch (TO_CONN(listener)->type) {
          case CONN_TYPE_AP_LISTENER:
            conn->state = AP_CONN_STATE_SOCKS_WAIT;
            TO_ENTRY_CONN(conn)->socks_request->socks_prefer_no_auth =
              listener->entry_cfg.socks_prefer_no_auth;
            break;
          case CONN_TYPE_AP_TRANS_LISTENER:
            TO_ENTRY_CONN(conn)->is_transparent_ap = 1;
            /* XXXX028 -- is this correct still, with the addition of
             * pending_entry_connections ? */
            conn->state = AP_CONN_STATE_CIRCUIT_WAIT;
            return connection_ap_process_transparent(TO_ENTRY_CONN(conn));
          case CONN_TYPE_AP_NATD_LISTENER:
            TO_ENTRY_CONN(conn)->is_transparent_ap = 1;
            conn->state = AP_CONN_STATE_NATD_WAIT;
            break;
          case CONN_TYPE_AP_HTTP_CONNECT_LISTENER:
            conn->state = AP_CONN_STATE_HTTP_CONNECT_WAIT;
        }
        break;
      case CONN_TYPE_DIR:
        conn->purpose = DIR_PURPOSE_SERVER;
        conn->state = DIR_CONN_STATE_SERVER_COMMAND_WAIT;
        break;
      case CONN_TYPE_CONTROL:
        conn->state = CONTROL_CONN_STATE_NEEDAUTH;
        break;
    }
    return 0;
  }
  
  /** Take conn, make a nonblocking socket; try to connect to
   * sa, binding to bindaddr if sa is not localhost. If fail, return -1 and if
   * applicable put your best guess about errno into *<b>socket_error</b>.
   * If connected return 1, if EAGAIN return 0.
   */
  MOCK_IMPL(STATIC int,
  connection_connect_sockaddr,(connection_t *conn,
                              const struct sockaddr *sa,
                              socklen_t sa_len,
                              const struct sockaddr *bindaddr,
                              socklen_t bindaddr_len,
                              int *socket_error))
  {
    tor_socket_t s;
    int inprogress = 0;
    const or_options_t *options = get_options();
  
    tor_assert(conn);
    tor_assert(sa);
    tor_assert(socket_error);
  
    if (net_is_completely_disabled()) {
      /* We should never even try to connect anyplace if the network is
       * completely shut off.
       *
       * (We don't check net_is_disabled() here, since we still sometimes
       * want to open connections when we're in soft hibernation.)
       */
      static ratelim_t disablenet_violated = RATELIM_INIT(30*60);
      *socket_error = SOCK_ERRNO(ENETUNREACH);
      log_fn_ratelim(&disablenet_violated, LOG_WARN, LD_BUG,
                     "Tried to open a socket with DisableNetwork set.");
      tor_fragile_assert();
      return -1;
    }
  
    const int protocol_family = sa->sa_family;
    const int proto = (sa->sa_family == AF_INET6 ||
                       sa->sa_family == AF_INET) ? IPPROTO_TCP : 0;
  
    s = tor_open_socket_nonblocking(protocol_family, SOCK_STREAM, proto);
    if (! SOCKET_OK(s)) {
      /*
       * Early OOS handler calls; it matters if it's an exhaustion-related
       * error or not.
       */
      *socket_error = tor_socket_errno(s);
      if (ERRNO_IS_RESOURCE_LIMIT(*socket_error)) {
        warn_too_many_conns();
        connection_check_oos(get_n_open_sockets(), 1);
      } else {
        log_warn(LD_NET,"Error creating network socket: %s",
                 tor_socket_strerror(*socket_error));
        connection_check_oos(get_n_open_sockets(), 0);
      }
      return -1;
    }
  
    if (make_socket_reuseable(s) < 0) {
      log_warn(LD_NET, "Error setting SO_REUSEADDR flag on new connection: %s",
               tor_socket_strerror(errno));
    }
  
    /*
     * We've got the socket open; give the OOS handler a chance to check
     * against configured maximum socket number, but tell it no exhaustion
     * failure.
     */
    connection_check_oos(get_n_open_sockets(), 0);
  
    if (bindaddr && bind(s, bindaddr, bindaddr_len) < 0) {
      *socket_error = tor_socket_errno(s);
      log_warn(LD_NET,"Error binding network socket: %s",
               tor_socket_strerror(*socket_error));
      tor_close_socket(s);
      return -1;
    }
  
    tor_assert(options);
    if (options->ConstrainedSockets)
      set_constrained_socket_buffers(s, (int)options->ConstrainedSockSize);
  
    if (connect(s, sa, sa_len) < 0) {
      int e = tor_socket_errno(s);
      if (!ERRNO_IS_CONN_EINPROGRESS(e)) {
        /* yuck. kill it. */
        *socket_error = e;
        log_info(LD_NET,
                 "connect() to socket failed: %s",
                 tor_socket_strerror(e));
        tor_close_socket(s);
        return -1;
      } else {
        inprogress = 1;
      }
    }
  
    /* it succeeded. we're connected. */
    log_fn(inprogress ? LOG_DEBUG : LOG_INFO, LD_NET,
           "Connection to socket %s (sock "TOR_SOCKET_T_FORMAT").",
           inprogress ? "in progress" : "established", s);
    conn->s = s;
    if (connection_add_connecting(conn) < 0) {
      /* no space, forget it */
      *socket_error = SOCK_ERRNO(ENOBUFS);
      return -1;
    }
  
    return inprogress ? 0 : 1;
  }
  
  /* Log a message if connection attempt is made when IPv4 or IPv6 is disabled.
   * Log a less severe message if we couldn't conform to ClientPreferIPv6ORPort
   * or ClientPreferIPv6ORPort. */
  static void
  connection_connect_log_client_use_ip_version(const connection_t *conn)
  {
    const or_options_t *options = get_options();
  
    /* Only clients care about ClientUseIPv4/6, bail out early on servers, and
     * on connections we don't care about */
    if (server_mode(options) || !conn || conn->type == CONN_TYPE_EXIT) {
      return;
    }
  
    /* We're only prepared to log OR and DIR connections here */
    if (conn->type != CONN_TYPE_OR && conn->type != CONN_TYPE_DIR) {
      return;
    }
  
    const int must_ipv4 = !fascist_firewall_use_ipv6(options);
    const int must_ipv6 = (options->ClientUseIPv4 == 0);
    const int pref_ipv6 = (conn->type == CONN_TYPE_OR
                           ? fascist_firewall_prefer_ipv6_orport(options)
                           : fascist_firewall_prefer_ipv6_dirport(options));
    tor_addr_t real_addr;
    tor_addr_make_null(&real_addr, AF_UNSPEC);
  
    /* OR conns keep the original address in real_addr, as addr gets overwritten
     * with the descriptor address */
    if (conn->type == CONN_TYPE_OR) {
      const or_connection_t *or_conn = TO_OR_CONN((connection_t *)conn);
      tor_addr_copy(&real_addr, &or_conn->real_addr);
    } else if (conn->type == CONN_TYPE_DIR) {
      tor_addr_copy(&real_addr, &conn->addr);
    }
  
    /* Check if we broke a mandatory address family restriction */
    if ((must_ipv4 && tor_addr_family(&real_addr) == AF_INET6)
        || (must_ipv6 && tor_addr_family(&real_addr) == AF_INET)) {
      static int logged_backtrace = 0;
      log_info(LD_BUG, "Outgoing %s connection to %s violated ClientUseIPv%s 0.",
               conn->type == CONN_TYPE_OR ? "OR" : "Dir",
               fmt_addr(&real_addr),
               options->ClientUseIPv4 == 0 ? "4" : "6");
      if (!logged_backtrace) {
        log_backtrace(LOG_INFO, LD_BUG, "Address came from");
        logged_backtrace = 1;
      }
    }
  
    /* Bridges are allowed to break IPv4/IPv6 ORPort preferences to connect to
     * the node's configured address when ClientPreferIPv6ORPort is auto */
    if (options->UseBridges && conn->type == CONN_TYPE_OR
        && options->ClientPreferIPv6ORPort == -1) {
      return;
    }
  
    /* Check if we couldn't satisfy an address family preference */
    if ((!pref_ipv6 && tor_addr_family(&real_addr) == AF_INET6)
        || (pref_ipv6 && tor_addr_family(&real_addr) == AF_INET)) {
      log_info(LD_NET, "Outgoing connection to %s doesn't satisfy "
               "ClientPreferIPv6%sPort %d, with ClientUseIPv4 %d, and "
               "fascist_firewall_use_ipv6 %d (ClientUseIPv6 %d and UseBridges "
               "%d).",
               fmt_addr(&real_addr),
               conn->type == CONN_TYPE_OR ? "OR" : "Dir",
               conn->type == CONN_TYPE_OR ? options->ClientPreferIPv6ORPort
                                          : options->ClientPreferIPv6DirPort,
               options->ClientUseIPv4, fascist_firewall_use_ipv6(options),
               options->ClientUseIPv6, options->UseBridges);
    }
  }
  
  /** Retrieve the outbound address depending on the protocol (IPv4 or IPv6)
   * and the connection type (relay, exit, ...)
   * Return a socket address or NULL in case nothing is configured.
   **/
  const tor_addr_t *
  conn_get_outbound_address(sa_family_t family,
               const or_options_t *options, unsigned int conn_type)
  {
    const tor_addr_t *ext_addr = NULL;
  
    int fam_index;
    switch (family) {
      case AF_INET:
        fam_index = 0;
        break;
      case AF_INET6:
        fam_index = 1;
        break;
      default:
        return NULL;
    }
  
    // If an exit connection, use the exit address (if present)
    if (conn_type == CONN_TYPE_EXIT) {
      if (!tor_addr_is_null(
          &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT][fam_index])) {
        ext_addr = &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT]
                   [fam_index];
      } else if (!tor_addr_is_null(
                   &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT_AND_OR]
                   [fam_index])) {
        ext_addr = &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT_AND_OR]
                   [fam_index];
      }
    } else { // All non-exit connections
      if (!tor_addr_is_null(
             &options->OutboundBindAddresses[OUTBOUND_ADDR_OR][fam_index])) {
        ext_addr = &options->OutboundBindAddresses[OUTBOUND_ADDR_OR]
                   [fam_index];
      } else if (!tor_addr_is_null(
                   &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT_AND_OR]
                   [fam_index])) {
        ext_addr = &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT_AND_OR]
                   [fam_index];
      }
    }
    return ext_addr;
  }
  
  /** Take conn, make a nonblocking socket; try to connect to
   * addr:port (port arrives in *host order*). If fail, return -1 and if
   * applicable put your best guess about errno into *<b>socket_error</b>.
   * Else assign s to conn-\>s: if connected return 1, if EAGAIN return 0.
   *
   * addr:port can be different to conn->addr:conn->port if connecting through
   * a proxy.
   *
   * address is used to make the logs useful.
   *
   * On success, add conn to the list of polled connections.
   */
  int
  connection_connect(connection_t *conn, const char *address,
                     const tor_addr_t *addr, uint16_t port, int *socket_error)
  {
    struct sockaddr_storage addrbuf;
    struct sockaddr_storage bind_addr_ss;
    struct sockaddr *bind_addr = NULL;
    struct sockaddr *dest_addr;
    int dest_addr_len, bind_addr_len = 0;
  
    /* Log if we didn't stick to ClientUseIPv4/6 or ClientPreferIPv6OR/DirPort
     */
    connection_connect_log_client_use_ip_version(conn);
  
    if (!tor_addr_is_loopback(addr)) {
      const tor_addr_t *ext_addr = NULL;
      ext_addr = conn_get_outbound_address(tor_addr_family(addr), get_options(),
                                           conn->type);
      if (ext_addr) {
        memset(&bind_addr_ss, 0, sizeof(bind_addr_ss));
        bind_addr_len = tor_addr_to_sockaddr(ext_addr, 0,
                                             (struct sockaddr *) &bind_addr_ss,
                                             sizeof(bind_addr_ss));
        if (bind_addr_len == 0) {
          log_warn(LD_NET,
                   "Error converting OutboundBindAddress %s into sockaddr. "
                   "Ignoring.", fmt_and_decorate_addr(ext_addr));
        } else {
          bind_addr = (struct sockaddr *)&bind_addr_ss;
        }
      }
    }
  
    memset(&addrbuf,0,sizeof(addrbuf));
    dest_addr = (struct sockaddr*) &addrbuf;
    dest_addr_len = tor_addr_to_sockaddr(addr, port, dest_addr, sizeof(addrbuf));
    tor_assert(dest_addr_len > 0);
  
    log_debug(LD_NET, "Connecting to %s:%u.",
              escaped_safe_str_client(address), port);
  
    return connection_connect_sockaddr(conn, dest_addr, dest_addr_len,
                                       bind_addr, bind_addr_len, socket_error);
  }
  
  #ifdef HAVE_SYS_UN_H
  
  /** Take conn, make a nonblocking socket; try to connect to
   * an AF_UNIX socket at socket_path. If fail, return -1 and if applicable
   * put your best guess about errno into *<b>socket_error</b>. Else assign s
   * to conn-\>s: if connected return 1, if EAGAIN return 0.
   *
   * On success, add conn to the list of polled connections.
   */
  int
  connection_connect_unix(connection_t *conn, const char *socket_path,
                          int *socket_error)
  {
    struct sockaddr_un dest_addr;
  
    tor_assert(socket_path);
  
    /* Check that we'll be able to fit it into dest_addr later */
    if (strlen(socket_path) + 1 > sizeof(dest_addr.sun_path)) {
      log_warn(LD_NET,
               "Path %s is too long for an AF_UNIX socket\n",
               escaped_safe_str_client(socket_path));
      *socket_error = SOCK_ERRNO(ENAMETOOLONG);
      return -1;
    }
  
    memset(&dest_addr, 0, sizeof(dest_addr));
    dest_addr.sun_family = AF_UNIX;
    strlcpy(dest_addr.sun_path, socket_path, sizeof(dest_addr.sun_path));
  
    log_debug(LD_NET,
              "Connecting to AF_UNIX socket at %s.",
              escaped_safe_str_client(socket_path));
  
    return connection_connect_sockaddr(conn,
                         (struct sockaddr *)&dest_addr, sizeof(dest_addr),
                         NULL, 0, socket_error);
  }
  
  #endif /* defined(HAVE_SYS_UN_H) */
  
  /** Convert state number to string representation for logging purposes.
   */
  static const char *
  connection_proxy_state_to_string(int state)
  {
    static const char *unknown = "???";
    static const char *states[] = {
      "PROXY_NONE",
      "PROXY_INFANT",
      "PROXY_HTTPS_WANT_CONNECT_OK",
      "PROXY_SOCKS4_WANT_CONNECT_OK",
      "PROXY_SOCKS5_WANT_AUTH_METHOD_NONE",
      "PROXY_SOCKS5_WANT_AUTH_METHOD_RFC1929",
      "PROXY_SOCKS5_WANT_AUTH_RFC1929_OK",
      "PROXY_SOCKS5_WANT_CONNECT_OK",
      "PROXY_CONNECTED",
    };
  
    if (state < PROXY_NONE || state > PROXY_CONNECTED)
      return unknown;
  
    return states[state];
  }
  
  /** Returns the proxy type used by tor for a single connection, for
   *  logging or high-level purposes. Don't use it to fill the
   *  <b>proxy_type</b> field of or_connection_t; use the actual proxy
   *  protocol instead.*/
  static int
  conn_get_proxy_type(const connection_t *conn)
  {
    const or_options_t *options = get_options();
  
    if (options->ClientTransportPlugin) {
      /* If we have plugins configured *and* this addr/port is a known bridge
       * with a transport, then we should be PROXY_PLUGGABLE. */
      const transport_t *transport = NULL;
      int r;
      r = get_transport_by_bridge_addrport(&conn->addr, conn->port, &transport);
      if (r == 0 && transport)
        return PROXY_PLUGGABLE;
    }
  
    /* In all other cases, we're using a global proxy. */
    if (options->HTTPSProxy)
      return PROXY_CONNECT;
    else if (options->Socks4Proxy)
      return PROXY_SOCKS4;
    else if (options->Socks5Proxy)
      return PROXY_SOCKS5;
    else
      return PROXY_NONE;
  }
  
  /* One byte for the version, one for the command, two for the
     port, and four for the addr... and, one more for the
     username NUL: */
  #define SOCKS4_STANDARD_BUFFER_SIZE (1 + 1 + 2 + 4 + 1)
  
  /** Write a proxy request of <b>type</b> (socks4, socks5, https) to conn
   * for conn->addr:conn->port, authenticating with the auth details given
   * in the configuration (if available). SOCKS 5 and HTTP CONNECT proxies
   * support authentication.
   *
   * Returns -1 if conn->addr is incompatible with the proxy protocol, and
   * 0 otherwise.
   *
   * Use connection_read_proxy_handshake() to complete the handshake.
   */
  int
  connection_proxy_connect(connection_t *conn, int type)
  {
    const or_options_t *options;
  
    tor_assert(conn);
  
    options = get_options();
  
    switch (type) {
      case PROXY_CONNECT: {
        char buf[1024];
        char *base64_authenticator=NULL;
        const char *authenticator = options->HTTPSProxyAuthenticator;
  
        /* Send HTTP CONNECT and authentication (if available) in
         * one request */
  
        if (authenticator) {
          base64_authenticator = alloc_http_authenticator(authenticator);
          if (!base64_authenticator)
            log_warn(LD_OR, "Encoding https authenticator failed");
        }
  
        if (base64_authenticator) {
          const char *addrport = fmt_addrport(&conn->addr, conn->port);
          tor_snprintf(buf, sizeof(buf), "CONNECT %s HTTP/1.1\r\n"
                       "Host: %s\r\n"
                       "Proxy-Authorization: Basic %s\r\n\r\n",
                       addrport,
                       addrport,
                       base64_authenticator);
          tor_free(base64_authenticator);
        } else {
          tor_snprintf(buf, sizeof(buf), "CONNECT %s HTTP/1.0\r\n\r\n",
                       fmt_addrport(&conn->addr, conn->port));
        }
  
        connection_buf_add(buf, strlen(buf), conn);
        conn->proxy_state = PROXY_HTTPS_WANT_CONNECT_OK;
        break;
      }
  
      case PROXY_SOCKS4: {
        unsigned char *buf;
        uint16_t portn;
        uint32_t ip4addr;
        size_t buf_size = 0;
        char *socks_args_string = NULL;
  
        /* Send a SOCKS4 connect request */
  
        if (tor_addr_family(&conn->addr) != AF_INET) {
          log_warn(LD_NET, "SOCKS4 client is incompatible with IPv6");
          return -1;
        }
  
        { /* If we are here because we are trying to connect to a
             pluggable transport proxy, check if we have any SOCKS
             arguments to transmit. If we do, compress all arguments to
             a single string in 'socks_args_string': */
  
          if (conn_get_proxy_type(conn) == PROXY_PLUGGABLE) {
            socks_args_string =
              pt_get_socks_args_for_proxy_addrport(&conn->addr, conn->port);
            if (socks_args_string)
              log_debug(LD_NET, "Sending out '%s' as our SOCKS argument string.",
                        socks_args_string);
          }
        }
  
        { /* Figure out the buffer size we need for the SOCKS message: */
  
          buf_size = SOCKS4_STANDARD_BUFFER_SIZE;
  
          /* If we have a SOCKS argument string, consider its size when
             calculating the buffer size: */
          if (socks_args_string)
            buf_size += strlen(socks_args_string);
        }
  
        buf = tor_malloc_zero(buf_size);
  
        ip4addr = tor_addr_to_ipv4n(&conn->addr);
        portn = htons(conn->port);
  
        buf[0] = 4; /* version */
        buf[1] = SOCKS_COMMAND_CONNECT; /* command */
        memcpy(buf + 2, &portn, 2); /* port */
        memcpy(buf + 4, &ip4addr, 4); /* addr */
  
        /* Next packet field is the userid. If we have pluggable
           transport SOCKS arguments, we have to embed them
           there. Otherwise, we use an empty userid.  */
        if (socks_args_string) { /* place the SOCKS args string: */
          tor_assert(strlen(socks_args_string) > 0);
          tor_assert(buf_size >=
                     SOCKS4_STANDARD_BUFFER_SIZE + strlen(socks_args_string));
          strlcpy((char *)buf + 8, socks_args_string, buf_size - 8);
          tor_free(socks_args_string);
        } else {
          buf[8] = 0; /* no userid */
        }
  
        connection_buf_add((char *)buf, buf_size, conn);
        tor_free(buf);
  
        conn->proxy_state = PROXY_SOCKS4_WANT_CONNECT_OK;
        break;
      }
  
      case PROXY_SOCKS5: {
        unsigned char buf[4]; /* fields: vers, num methods, method list */
  
        /* Send a SOCKS5 greeting (connect request must wait) */
  
        buf[0] = 5; /* version */
  
        /* We have to use SOCKS5 authentication, if we have a
           Socks5ProxyUsername or if we want to pass arguments to our
           pluggable transport proxy: */
        if ((options->Socks5ProxyUsername) ||
            (conn_get_proxy_type(conn) == PROXY_PLUGGABLE &&
             (get_socks_args_by_bridge_addrport(&conn->addr, conn->port)))) {
        /* number of auth methods */
          buf[1] = 2;
          buf[2] = 0x00; /* no authentication */
          buf[3] = 0x02; /* rfc1929 Username/Passwd auth */
          conn->proxy_state = PROXY_SOCKS5_WANT_AUTH_METHOD_RFC1929;
        } else {
          buf[1] = 1;
          buf[2] = 0x00; /* no authentication */
          conn->proxy_state = PROXY_SOCKS5_WANT_AUTH_METHOD_NONE;
        }
  
        connection_buf_add((char *)buf, 2 + buf[1], conn);
        break;
      }
  
      default:
        log_err(LD_BUG, "Invalid proxy protocol, %d", type);
        tor_fragile_assert();
        return -1;
    }
  
    log_debug(LD_NET, "set state %s",
              connection_proxy_state_to_string(conn->proxy_state));
  
    return 0;
  }
  
  /** Read conn's inbuf. If the http response from the proxy is all
   * here, make sure it's good news, then return 1. If it's bad news,
   * return -1. Else return 0 and hope for better luck next time.
   */
  static int
  connection_read_https_proxy_response(connection_t *conn)
  {
    char *headers;
    char *reason=NULL;
    int status_code;
    time_t date_header;
  
    switch (fetch_from_buf_http(conn->inbuf,
                                &headers, MAX_HEADERS_SIZE,
                                NULL, NULL, 10000, 0)) {
      case -1: /* overflow */
        log_warn(LD_PROTOCOL,
                 "Your https proxy sent back an oversized response. Closing.");
        return -1;
      case 0:
        log_info(LD_NET,"https proxy response not all here yet. Waiting.");
        return 0;
      /* case 1, fall through */
    }
  
    if (parse_http_response(headers, &status_code, &date_header,
                            NULL, &reason) < 0) {
      log_warn(LD_NET,
               "Unparseable headers from proxy (connecting to '%s'). Closing.",
               conn->address);
      tor_free(headers);
      return -1;
    }
    tor_free(headers);
    if (!reason) reason = tor_strdup("[no reason given]");
  
    if (status_code == 200) {
      log_info(LD_NET,
               "HTTPS connect to '%s' successful! (200 %s) Starting TLS.",
               conn->address, escaped(reason));
      tor_free(reason);
      return 1;
    }
    /* else, bad news on the status code */
    switch (status_code) {
      case 403:
        log_warn(LD_NET,
               "The https proxy refused to allow connection to %s "
               "(status code %d, %s). Closing.",
               conn->address, status_code, escaped(reason));
        break;
      default:
        log_warn(LD_NET,
               "The https proxy sent back an unexpected status code %d (%s). "
               "Closing.",
               status_code, escaped(reason));
        break;
    }
    tor_free(reason);
    return -1;
  }
  
  /** Send SOCKS5 CONNECT command to <b>conn</b>, copying <b>conn->addr</b>
   * and <b>conn->port</b> into the request.
   */
  static void
  connection_send_socks5_connect(connection_t *conn)
  {
    unsigned char buf[1024];
    size_t reqsize = 6;
    uint16_t port = htons(conn->port);
  
    buf[0] = 5; /* version */
    buf[1] = SOCKS_COMMAND_CONNECT; /* command */
    buf[2] = 0; /* reserved */
  
    if (tor_addr_family(&conn->addr) == AF_INET) {
      uint32_t addr = tor_addr_to_ipv4n(&conn->addr);
  
      buf[3] = 1;
      reqsize += 4;
      memcpy(buf + 4, &addr, 4);
      memcpy(buf + 8, &port, 2);
    } else { /* AF_INET6 */
      buf[3] = 4;
      reqsize += 16;
      memcpy(buf + 4, tor_addr_to_in6_addr8(&conn->addr), 16);
      memcpy(buf + 20, &port, 2);
    }
  
    connection_buf_add((char *)buf, reqsize, conn);
  
    conn->proxy_state = PROXY_SOCKS5_WANT_CONNECT_OK;
  }
  
  /** Wrapper around fetch_from_buf_socks_client: see that functions
   * for documentation of its behavior. */
  static int
  connection_fetch_from_buf_socks_client(connection_t *conn,
                                         int state, char **reason)
  {
    return fetch_from_buf_socks_client(conn->inbuf, state, reason);
  }
  
  /** Call this from connection_*_process_inbuf() to advance the proxy
   * handshake.
   *
   * No matter what proxy protocol is used, if this function returns 1, the
   * handshake is complete, and the data remaining on inbuf may contain the
   * start of the communication with the requested server.
   *
   * Returns 0 if the current buffer contains an incomplete response, and -1
   * on error.
   */
  int
  connection_read_proxy_handshake(connection_t *conn)
  {
    int ret = 0;
    char *reason = NULL;
  
    log_debug(LD_NET, "enter state %s",
              connection_proxy_state_to_string(conn->proxy_state));
  
    switch (conn->proxy_state) {
      case PROXY_HTTPS_WANT_CONNECT_OK:
        ret = connection_read_https_proxy_response(conn);
        if (ret == 1)
          conn->proxy_state = PROXY_CONNECTED;
        break;
  
      case PROXY_SOCKS4_WANT_CONNECT_OK:
        ret = connection_fetch_from_buf_socks_client(conn,
                                                     conn->proxy_state,
                                                     &reason);
        if (ret == 1)
          conn->proxy_state = PROXY_CONNECTED;
        break;
  
      case PROXY_SOCKS5_WANT_AUTH_METHOD_NONE:
        ret = connection_fetch_from_buf_socks_client(conn,
                                                     conn->proxy_state,
                                                     &reason);
        /* no auth needed, do connect */
        if (ret == 1) {
          connection_send_socks5_connect(conn);
          ret = 0;
        }
        break;
  
      case PROXY_SOCKS5_WANT_AUTH_METHOD_RFC1929:
        ret = connection_fetch_from_buf_socks_client(conn,
                                                     conn->proxy_state,
                                                     &reason);
  
        /* send auth if needed, otherwise do connect */
        if (ret == 1) {
          connection_send_socks5_connect(conn);
          ret = 0;
        } else if (ret == 2) {
          unsigned char buf[1024];
          size_t reqsize, usize, psize;
          const char *user, *pass;
          char *socks_args_string = NULL;
  
          if (conn_get_proxy_type(conn) == PROXY_PLUGGABLE) {
            socks_args_string =
              pt_get_socks_args_for_proxy_addrport(&conn->addr, conn->port);
            if (!socks_args_string) {
              log_warn(LD_NET, "Could not create SOCKS args string for PT.");
              ret = -1;
              break;
            }
  
            log_debug(LD_NET, "PT SOCKS5 arguments: %s", socks_args_string);
            tor_assert(strlen(socks_args_string) > 0);
            tor_assert(strlen(socks_args_string) <= MAX_SOCKS5_AUTH_SIZE_TOTAL);
  
            if (strlen(socks_args_string) > MAX_SOCKS5_AUTH_FIELD_SIZE) {
              user = socks_args_string;
              usize = MAX_SOCKS5_AUTH_FIELD_SIZE;
              pass = socks_args_string + MAX_SOCKS5_AUTH_FIELD_SIZE;
              psize = strlen(socks_args_string) - MAX_SOCKS5_AUTH_FIELD_SIZE;
            } else {
              user = socks_args_string;
              usize = strlen(socks_args_string);
              pass = "\0";
              psize = 1;
            }
          } else if (get_options()->Socks5ProxyUsername) {
            user = get_options()->Socks5ProxyUsername;
            pass = get_options()->Socks5ProxyPassword;
            tor_assert(user && pass);
            usize = strlen(user);
            psize = strlen(pass);
          } else {
            log_err(LD_BUG, "We entered %s for no reason!", __func__);
            tor_fragile_assert();
            ret = -1;
            break;
          }
  
          /* Username and password lengths should have been checked
             above and during torrc parsing. */
          tor_assert(usize <= MAX_SOCKS5_AUTH_FIELD_SIZE &&
                     psize <= MAX_SOCKS5_AUTH_FIELD_SIZE);
          reqsize = 3 + usize + psize;
  
          buf[0] = 1; /* negotiation version */
          buf[1] = usize;
          memcpy(buf + 2, user, usize);
          buf[2 + usize] = psize;
          memcpy(buf + 3 + usize, pass, psize);
  
          if (socks_args_string)
            tor_free(socks_args_string);
  
          connection_buf_add((char *)buf, reqsize, conn);
  
          conn->proxy_state = PROXY_SOCKS5_WANT_AUTH_RFC1929_OK;
          ret = 0;
        }
        break;
  
      case PROXY_SOCKS5_WANT_AUTH_RFC1929_OK:
        ret = connection_fetch_from_buf_socks_client(conn,
                                                     conn->proxy_state,
                                                     &reason);
        /* send the connect request */
        if (ret == 1) {
          connection_send_socks5_connect(conn);
          ret = 0;
        }
        break;
  
      case PROXY_SOCKS5_WANT_CONNECT_OK:
        ret = connection_fetch_from_buf_socks_client(conn,
                                                     conn->proxy_state,
                                                     &reason);
        if (ret == 1)
          conn->proxy_state = PROXY_CONNECTED;
        break;
  
      default:
        log_err(LD_BUG, "Invalid proxy_state for reading, %d",
                conn->proxy_state);
        tor_fragile_assert();
        ret = -1;
        break;
    }
  
    log_debug(LD_NET, "leaving state %s",
              connection_proxy_state_to_string(conn->proxy_state));
  
    if (ret < 0) {
      if (reason) {
        log_warn(LD_NET, "Proxy Client: unable to connect to %s:%d (%s)",
                  conn->address, conn->port, escaped(reason));
        tor_free(reason);
      } else {
        log_warn(LD_NET, "Proxy Client: unable to connect to %s:%d",
                  conn->address, conn->port);
      }
    } else if (ret == 1) {
      log_info(LD_NET, "Proxy Client: connection to %s:%d successful",
                conn->address, conn->port);
    }
  
    return ret;
  }
  
  /** Given a list of listener connections in <b>old_conns</b>, and list of
   * port_cfg_t entries in <b>ports</b>, open a new listener for every port in
   * <b>ports</b> that does not already have a listener in <b>old_conns</b>.
   *
   * Remove from <b>old_conns</b> every connection that has a corresponding
   * entry in <b>ports</b>.  Add to <b>new_conns</b> new every connection we
   * launch. If we may need to perform socket rebind when creating new
   * listener that replaces old one, create a <b>listener_replacement_t</b>
   * struct for affected pair  and add it to <b>replacements</b>.
   *
   * If <b>control_listeners_only</b> is true, then we only open control
   * listeners, and we do not remove any noncontrol listeners from
   * old_conns.
   *
   * Return 0 on success, -1 on failure.
   **/
  static int
  retry_listener_ports(smartlist_t *old_conns,
                       const smartlist_t *ports,
                       smartlist_t *new_conns,
                       smartlist_t *replacements,
                       int control_listeners_only)
  {
  #ifndef ENABLE_LISTENER_REBIND
    (void)replacements;
  #endif
  
    smartlist_t *launch = smartlist_new();
    int r = 0;
  
    if (control_listeners_only) {
      SMARTLIST_FOREACH(ports, port_cfg_t *, p, {
          if (p->type == CONN_TYPE_CONTROL_LISTENER)
            smartlist_add(launch, p);
      });
    } else {
      smartlist_add_all(launch, ports);
    }
  
    /* Iterate through old_conns, comparing it to launch: remove from both lists
     * each pair of elements that corresponds to the same port. */
    SMARTLIST_FOREACH_BEGIN(old_conns, connection_t *, conn) {
      const port_cfg_t *found_port = NULL;
  
      /* Okay, so this is a listener.  Is it configured? */
      /* That is, is it either: 1) exact match - address and port
       * pair match exactly between old listener and new port; or 2)
       * wildcard match - port matches exactly, but *one* of the
       * addresses is wildcard (0.0.0.0 or ::)?
       */
      SMARTLIST_FOREACH_BEGIN(launch, const port_cfg_t *, wanted) {
        if (conn->type != wanted->type)
          continue;
        if ((conn->socket_family != AF_UNIX && wanted->is_unix_addr) ||
            (conn->socket_family == AF_UNIX && ! wanted->is_unix_addr))
          continue;
  
        if (wanted->server_cfg.no_listen)
          continue; /* We don't want to open a listener for this one */
  
        if (wanted->is_unix_addr) {
          if (conn->socket_family == AF_UNIX &&
              !strcmp(wanted->unix_addr, conn->address)) {
            found_port = wanted;
            break;
          }
        } else {
          /* Numeric values of old and new port match exactly. */
          const int port_matches_exact = (wanted->port == conn->port);
          /* Ports match semantically - either their specific values
             match exactly, or new port is 'auto'.
           */
          const int port_matches = (wanted->port == CFG_AUTO_PORT ||
                                    port_matches_exact);
  
          if (port_matches && tor_addr_eq(&wanted->addr, &conn->addr)) {
            found_port = wanted;
            break;
          }
  #ifdef ENABLE_LISTENER_REBIND
          /* Rebinding may be needed if all of the following are true:
           * 1) Address family is the same in old and new listeners.
           * 2) Port number matches exactly (numeric value is the same).
           * 3) *One* of listeners (either old one or new one) has a
           *    wildcard IP address (0.0.0.0 or [::]).
           *
           * These are the exact conditions for a first bind() syscall
           * to fail with EADDRINUSE.
           */
          const int may_need_rebind =
            tor_addr_family(&wanted->addr) == tor_addr_family(&conn->addr) &&
            port_matches_exact && bool_neq(tor_addr_is_null(&wanted->addr),
                                           tor_addr_is_null(&conn->addr));
          if (replacements && may_need_rebind) {
            listener_replacement_t *replacement =
              tor_malloc(sizeof(listener_replacement_t));
  
            replacement->old_conn = conn;
            replacement->new_port = wanted;
            smartlist_add(replacements, replacement);
  
            SMARTLIST_DEL_CURRENT(launch, wanted);
            SMARTLIST_DEL_CURRENT(old_conns, conn);
            break;
          }
  #endif
        }
      } SMARTLIST_FOREACH_END(wanted);
  
      if (found_port) {
        /* This listener is already running; we don't need to launch it. */
        //log_debug(LD_NET, "Already have %s on %s:%d",
        //    conn_type_to_string(found_port->type), conn->address, conn->port);
        smartlist_remove(launch, found_port);
        /* And we can remove the connection from old_conns too. */
        SMARTLIST_DEL_CURRENT(old_conns, conn);
      }
    } SMARTLIST_FOREACH_END(conn);
  
    /* Now open all the listeners that are configured but not opened. */
    SMARTLIST_FOREACH_BEGIN(launch, const port_cfg_t *, port) {
      int skip = 0;
      connection_t *conn = connection_listener_new_for_port(port, &skip, NULL);
  
      if (conn && new_conns)
        smartlist_add(new_conns, conn);
      else if (!skip)
        r = -1;
    } SMARTLIST_FOREACH_END(port);
  
    smartlist_free(launch);
  
    return r;
  }
  
  /** Launch listeners for each port you should have open.  Only launch
   * listeners who are not already open, and only close listeners we no longer
   * want.
   *
   * Add all new connections to <b>new_conns</b>.
   *
   * If <b>close_all_noncontrol</b> is true, then we only open control
   * listeners, and we close all other listeners.
   */
  int
  retry_all_listeners(smartlist_t *new_conns, int close_all_noncontrol)
  {
    smartlist_t *listeners = smartlist_new();
    smartlist_t *replacements = smartlist_new();
    const or_options_t *options = get_options();
    int retval = 0;
    const uint16_t old_or_port = router_get_advertised_or_port(options);
    const uint16_t old_or_port_ipv6 =
      router_get_advertised_or_port_by_af(options,AF_INET6);
    const uint16_t old_dir_port = router_get_advertised_dir_port(options, 0);
  
    SMARTLIST_FOREACH_BEGIN(get_connection_array(), connection_t *, conn) {
      if (connection_is_listener(conn) && !conn->marked_for_close)
        smartlist_add(listeners, conn);
    } SMARTLIST_FOREACH_END(conn);
  
    if (retry_listener_ports(listeners,
                             get_configured_ports(),
                             new_conns,
                             replacements,
                             close_all_noncontrol) < 0)
      retval = -1;
  
  #ifdef ENABLE_LISTENER_REBIND
    SMARTLIST_FOREACH_BEGIN(replacements, listener_replacement_t *, r) {
      int addr_in_use = 0;
      int skip = 0;
  
      tor_assert(r->new_port);
      tor_assert(r->old_conn);
  
      connection_t *new_conn =
        connection_listener_new_for_port(r->new_port, &skip, &addr_in_use);
      connection_t *old_conn = r->old_conn;
  
      if (skip)
        continue;
  
      connection_close_immediate(old_conn);
      connection_mark_for_close(old_conn);
  
      if (addr_in_use) {
        new_conn = connection_listener_new_for_port(r->new_port,
                                                    &skip, &addr_in_use);
      }
  
      tor_assert(new_conn);
  
      smartlist_add(new_conns, new_conn);
  
      log_notice(LD_NET, "Closed no-longer-configured %s on %s:%d "
                         "(replaced by %s:%d)",
                 conn_type_to_string(old_conn->type), old_conn->address,
                 old_conn->port, new_conn->address, new_conn->port);
    } SMARTLIST_FOREACH_END(r);
  #endif
  
    /* Any members that were still in 'listeners' don't correspond to
     * any configured port.  Kill 'em. */
    SMARTLIST_FOREACH_BEGIN(listeners, connection_t *, conn) {
      log_notice(LD_NET, "Closing no-longer-configured %s on %s:%d",
                 conn_type_to_string(conn->type), conn->address, conn->port);
      connection_close_immediate(conn);
      connection_mark_for_close(conn);
    } SMARTLIST_FOREACH_END(conn);
  
    smartlist_free(listeners);
    /* Cleanup any remaining listener replacement. */
    SMARTLIST_FOREACH(replacements, listener_replacement_t *, r, tor_free(r));
    smartlist_free(replacements);
  
    if (old_or_port != router_get_advertised_or_port(options) ||
        old_or_port_ipv6 != router_get_advertised_or_port_by_af(options,
                                                                AF_INET6) ||
        old_dir_port != router_get_advertised_dir_port(options, 0)) {
      /* Our chosen ORPort or DirPort is not what it used to be: the
       * descriptor we had (if any) should be regenerated.  (We won't
       * automatically notice this because of changes in the option,
       * since the value could be "auto".) */
      mark_my_descriptor_dirty("Chosen Or/DirPort changed");
    }
  
    return retval;
  }
  
  /** Mark every listener of type other than CONTROL_LISTENER to be closed. */
  void
  connection_mark_all_noncontrol_listeners(void)
  {
    SMARTLIST_FOREACH_BEGIN(get_connection_array(), connection_t *, conn) {
      if (conn->marked_for_close)
        continue;
      if (conn->type == CONN_TYPE_CONTROL_LISTENER)
        continue;
      if (connection_is_listener(conn))
        connection_mark_for_close(conn);
    } SMARTLIST_FOREACH_END(conn);
  }
  
  /** Mark every external connection not used for controllers for close. */
  void
  connection_mark_all_noncontrol_connections(void)
  {
    SMARTLIST_FOREACH_BEGIN(get_connection_array(), connection_t *, conn) {
      if (conn->marked_for_close)
        continue;
      switch (conn->type) {
        case CONN_TYPE_CONTROL_LISTENER:
        case CONN_TYPE_CONTROL:
          break;
        case CONN_TYPE_AP:
          connection_mark_unattached_ap(TO_ENTRY_CONN(conn),
                                        END_STREAM_REASON_HIBERNATING);
          break;
        case CONN_TYPE_OR:
          {
            or_connection_t *orconn = TO_OR_CONN(conn);
            if (orconn->chan) {
              connection_or_close_normally(orconn, 0);
            } else {
              /*
               * There should have been one, but mark for close and hope
               * for the best..
               */
              connection_mark_for_close(conn);
            }
          }
          break;
        default:
          connection_mark_for_close(conn);
          break;
      }
    } SMARTLIST_FOREACH_END(conn);
  }
  
  /** Return 1 if we should apply rate limiting to <b>conn</b>, and 0
   * otherwise.
   * Right now this just checks if it's an internal IP address or an
   * internal connection. We also should, but don't, check if the connection
   * uses pluggable transports, since we should then limit it even if it
   * comes from an internal IP address. */
  static int
  connection_is_rate_limited(connection_t *conn)
  {
    const or_options_t *options = get_options();
    if (conn->linked)
      return 0; /* Internal connection */
    else if (! options->CountPrivateBandwidth &&
             (tor_addr_family(&conn->addr) == AF_UNSPEC || /* no address */
              tor_addr_family(&conn->addr) == AF_UNIX ||   /* no address */
              tor_addr_is_internal(&conn->addr, 0)))
      return 0; /* Internal address */
    else
      return 1;
  }
  
  /** When was either global write bucket last empty? If this was recent, then
   * we're probably low on bandwidth, and we should be stingy with our bandwidth
   * usage. */
  static time_t write_buckets_last_empty_at = -100;
  
  /** How many seconds of no active local circuits will make the
   * connection revert to the "relayed" bandwidth class? */
  #define CLIENT_IDLE_TIME_FOR_PRIORITY 30
  
  /** Return 1 if <b>conn</b> should use tokens from the "relayed"
   * bandwidth rates, else 0. Currently, only OR conns with bandwidth
   * class 1, and directory conns that are serving data out, count.
   */
  static int
  connection_counts_as_relayed_traffic(connection_t *conn, time_t now)
  {
    if (conn->type == CONN_TYPE_OR &&
        connection_or_client_used(TO_OR_CONN(conn)) +
                                  CLIENT_IDLE_TIME_FOR_PRIORITY < now)
      return 1;
    if (conn->type == CONN_TYPE_DIR && DIR_CONN_IS_SERVER(conn))
      return 1;
    return 0;
  }
  
  /** Helper function to decide how many bytes out of <b>global_bucket</b>
   * we're willing to use for this transaction. <b>base</b> is the size
   * of a cell on the network; <b>priority</b> says whether we should
   * write many of them or just a few; and <b>conn_bucket</b> (if
   * non-negative) provides an upper limit for our answer. */
  static ssize_t
  connection_bucket_get_share(int base, int priority,
                              ssize_t global_bucket_val, ssize_t conn_bucket)
  {
    ssize_t at_most;
    ssize_t num_bytes_high = (priority ? 32 : 16) * base;
    ssize_t num_bytes_low = (priority ? 4 : 2) * base;
  
    /* Do a rudimentary limiting so one circuit can't hog a connection.
     * Pick at most 32 cells, at least 4 cells if possible, and if we're in
     * the middle pick 1/8 of the available bandwidth. */
    at_most = global_bucket_val / 8;
    at_most -= (at_most % base); /* round down */
    if (at_most > num_bytes_high) /* 16 KB, or 8 KB for low-priority */
      at_most = num_bytes_high;
    else if (at_most < num_bytes_low) /* 2 KB, or 1 KB for low-priority */
      at_most = num_bytes_low;
  
    if (at_most > global_bucket_val)
      at_most = global_bucket_val;
  
    if (conn_bucket >= 0 && at_most > conn_bucket)
      at_most = conn_bucket;
  
    if (at_most < 0)
      return 0;
    return at_most;
  }
  
  /** How many bytes at most can we read onto this connection? */
  static ssize_t
  connection_bucket_read_limit(connection_t *conn, time_t now)
  {
    int base = RELAY_PAYLOAD_SIZE;
    int priority = conn->type != CONN_TYPE_DIR;
    ssize_t conn_bucket = -1;
    size_t global_bucket_val = token_bucket_rw_get_read(&global_bucket);
  
    if (connection_speaks_cells(conn)) {
      or_connection_t *or_conn = TO_OR_CONN(conn);
      if (conn->state == OR_CONN_STATE_OPEN)
        conn_bucket = token_bucket_rw_get_read(&or_conn->bucket);
      base = get_cell_network_size(or_conn->wide_circ_ids);
    }
  
    if (!connection_is_rate_limited(conn)) {
      /* be willing to read on local conns even if our buckets are empty */
      return conn_bucket>=0 ? conn_bucket : 1<<14;
    }
  
    if (connection_counts_as_relayed_traffic(conn, now)) {
      size_t relayed = token_bucket_rw_get_read(&global_relayed_bucket);
      global_bucket_val = MIN(global_bucket_val, relayed);
    }
  
    return connection_bucket_get_share(base, priority,
                                       global_bucket_val, conn_bucket);
  }
  
  /** How many bytes at most can we write onto this connection? */
  ssize_t
  connection_bucket_write_limit(connection_t *conn, time_t now)
  {
    int base = RELAY_PAYLOAD_SIZE;
    int priority = conn->type != CONN_TYPE_DIR;
    size_t conn_bucket = conn->outbuf_flushlen;
    size_t global_bucket_val = token_bucket_rw_get_write(&global_bucket);
  
    if (!connection_is_rate_limited(conn)) {
      /* be willing to write to local conns even if our buckets are empty */
      return conn->outbuf_flushlen;
    }
  
    if (connection_speaks_cells(conn)) {
      /* use the per-conn write limit if it's lower */
      or_connection_t *or_conn = TO_OR_CONN(conn);
      if (conn->state == OR_CONN_STATE_OPEN)
        conn_bucket = MIN(conn_bucket,
                          token_bucket_rw_get_write(&or_conn->bucket));
      base = get_cell_network_size(or_conn->wide_circ_ids);
    }
  
    if (connection_counts_as_relayed_traffic(conn, now)) {
      size_t relayed = token_bucket_rw_get_write(&global_relayed_bucket);
      global_bucket_val = MIN(global_bucket_val, relayed);
    }
  
    return connection_bucket_get_share(base, priority,
                                       global_bucket_val, conn_bucket);
  }
  
  /** Return 1 if the global write buckets are low enough that we
   * shouldn't send <b>attempt</b> bytes of low-priority directory stuff
   * out to <b>conn</b>. Else return 0.
  
   * Priority was 1 for v1 requests (directories and running-routers),
   * and 2 for v2 requests and later (statuses and descriptors).
   *
   * There are a lot of parameters we could use here:
   * - global_relayed_write_bucket. Low is bad.
   * - global_write_bucket. Low is bad.
   * - bandwidthrate. Low is bad.
   * - bandwidthburst. Not a big factor?
   * - attempt. High is bad.
   * - total bytes queued on outbufs. High is bad. But I'm wary of
   *   using this, since a few slow-flushing queues will pump up the
   *   number without meaning what we meant to mean. What we really
   *   mean is "total directory bytes added to outbufs recently", but
   *   that's harder to quantify and harder to keep track of.
   */
  int
  global_write_bucket_low(connection_t *conn, size_t attempt, int priority)
  {
    size_t smaller_bucket =
      MIN(token_bucket_rw_get_write(&global_bucket),
          token_bucket_rw_get_write(&global_relayed_bucket));
    if (authdir_mode(get_options()) && priority>1)
      return 0; /* there's always room to answer v2 if we're an auth dir */
  
    if (!connection_is_rate_limited(conn))
      return 0; /* local conns don't get limited */
  
    if (smaller_bucket < attempt)
      return 1; /* not enough space no matter the priority */
  
    {
      const time_t diff = approx_time() - write_buckets_last_empty_at;
      if (diff <= 1)
        return 1; /* we're already hitting our limits, no more please */
    }
  
    if (priority == 1) { /* old-style v1 query */
      /* Could we handle *two* of these requests within the next two seconds? */
      const or_options_t *options = get_options();
      size_t can_write = (size_t) (smaller_bucket
        + 2*(options->RelayBandwidthRate ? options->RelayBandwidthRate :
             options->BandwidthRate));
      if (can_write < 2*attempt)
        return 1;
    } else { /* v2 query */
      /* no further constraints yet */
    }
    return 0;
  }
  
  /** When did we last tell the accounting subsystem about transmitted
   * bandwidth? */
  static time_t last_recorded_accounting_at = 0;
  
  /** Helper: adjusts our bandwidth history and informs the controller as
   * appropriate, given that we have just read <b>num_read</b> bytes and written
   * <b>num_written</b> bytes on <b>conn</b>. */
  static void
  record_num_bytes_transferred_impl(connection_t *conn,
                               time_t now, size_t num_read, size_t num_written)
  {
    /* Count bytes of answering direct and tunneled directory requests */
    if (conn->type == CONN_TYPE_DIR && conn->purpose == DIR_PURPOSE_SERVER) {
      if (num_read > 0)
        rep_hist_note_dir_bytes_read(num_read, now);
      if (num_written > 0)
        rep_hist_note_dir_bytes_written(num_written, now);
    }
  
    if (!connection_is_rate_limited(conn))
      return; /* local IPs are free */
  
    if (conn->type == CONN_TYPE_OR)
      rep_hist_note_or_conn_bytes(conn->global_identifier, num_read,
                                  num_written, now);
  
    if (num_read > 0) {
      rep_hist_note_bytes_read(num_read, now);
    }
    if (num_written > 0) {
      rep_hist_note_bytes_written(num_written, now);
    }
    if (conn->type == CONN_TYPE_EXIT)
      rep_hist_note_exit_bytes(conn->port, num_written, num_read);
  
    /* Remember these bytes towards statistics. */
    stats_increment_bytes_read_and_written(num_read, num_written);
  
    /* Remember these bytes towards accounting. */
    if (accounting_is_enabled(get_options())) {
      if (now > last_recorded_accounting_at && last_recorded_accounting_at) {
        accounting_add_bytes(num_read, num_written,
                             (int)(now - last_recorded_accounting_at));
      } else {
        accounting_add_bytes(num_read, num_written, 0);
      }
      last_recorded_accounting_at = now;
    }
  }
  
  /** We just read <b>num_read</b> and wrote <b>num_written</b> bytes
   * onto <b>conn</b>. Decrement buckets appropriately. */
  static void
  connection_buckets_decrement(connection_t *conn, time_t now,
                               size_t num_read, size_t num_written)
  {
    if (num_written >= INT_MAX || num_read >= INT_MAX) {
      log_err(LD_BUG, "Value out of range. num_read=%lu, num_written=%lu, "
               "connection type=%s, state=%s",
               (unsigned long)num_read, (unsigned long)num_written,
               conn_type_to_string(conn->type),
               conn_state_to_string(conn->type, conn->state));
      tor_assert_nonfatal_unreached();
      if (num_written >= INT_MAX)
        num_written = 1;
      if (num_read >= INT_MAX)
        num_read = 1;
    }
  
    record_num_bytes_transferred_impl(conn, now, num_read, num_written);
  
    if (!connection_is_rate_limited(conn))
      return; /* local IPs are free */
  
    unsigned flags = 0;
    if (connection_counts_as_relayed_traffic(conn, now)) {
      flags = token_bucket_rw_dec(&global_relayed_bucket, num_read, num_written);
    }
    flags |= token_bucket_rw_dec(&global_bucket, num_read, num_written);
  
    if (flags & TB_WRITE) {
      write_buckets_last_empty_at = now;
    }
    if (connection_speaks_cells(conn) && conn->state == OR_CONN_STATE_OPEN) {
      or_connection_t *or_conn = TO_OR_CONN(conn);
      token_bucket_rw_dec(&or_conn->bucket, num_read, num_written);
    }
  }
  
  /**
   * Mark <b>conn</b> as needing to stop reading because bandwidth has been
   * exhausted.  If <b>is_global_bw</b>, it is closing because global bandwidth
   * limit has been exhausted.  Otherwise, it is closing because its own
   * bandwidth limit has been exhausted.
   */
  void
  connection_read_bw_exhausted(connection_t *conn, bool is_global_bw)
  {
    (void)is_global_bw;
    conn->read_blocked_on_bw = 1;
    connection_stop_reading(conn);
    reenable_blocked_connection_schedule();
  }
  
  /**
   * Mark <b>conn</b> as needing to stop reading because write bandwidth has
   * been exhausted.  If <b>is_global_bw</b>, it is closing because global
   * bandwidth limit has been exhausted.  Otherwise, it is closing because its
   * own bandwidth limit has been exhausted.
  */
  void
  connection_write_bw_exhausted(connection_t *conn, bool is_global_bw)
  {
    (void)is_global_bw;
    conn->write_blocked_on_bw = 1;
    connection_stop_writing(conn);
    reenable_blocked_connection_schedule();
  }
  
  /** If we have exhausted our global buckets, or the buckets for conn,
   * stop reading. */
  void
  connection_consider_empty_read_buckets(connection_t *conn)
  {
    const char *reason;
  
    if (!connection_is_rate_limited(conn))
      return; /* Always okay. */
  
    int is_global = 1;
  
    if (token_bucket_rw_get_read(&global_bucket) <= 0) {
      reason = "global read bucket exhausted. Pausing.";
    } else if (connection_counts_as_relayed_traffic(conn, approx_time()) &&
               token_bucket_rw_get_read(&global_relayed_bucket) <= 0) {
      reason = "global relayed read bucket exhausted. Pausing.";
    } else if (connection_speaks_cells(conn) &&
               conn->state == OR_CONN_STATE_OPEN &&
               token_bucket_rw_get_read(&TO_OR_CONN(conn)->bucket) <= 0) {
      reason = "connection read bucket exhausted. Pausing.";
      is_global = false;
    } else
      return; /* all good, no need to stop it */
  
    LOG_FN_CONN(conn, (LOG_DEBUG, LD_NET, "%s", reason));
    connection_read_bw_exhausted(conn, is_global);
  }
  
  /** If we have exhausted our global buckets, or the buckets for conn,
   * stop writing. */
  void
  connection_consider_empty_write_buckets(connection_t *conn)
  {
    const char *reason;
  
    if (!connection_is_rate_limited(conn))
      return; /* Always okay. */
  
    bool is_global = true;
    if (token_bucket_rw_get_write(&global_bucket) <= 0) {
      reason = "global write bucket exhausted. Pausing.";
    } else if (connection_counts_as_relayed_traffic(conn, approx_time()) &&
               token_bucket_rw_get_write(&global_relayed_bucket) <= 0) {
      reason = "global relayed write bucket exhausted. Pausing.";
    } else if (connection_speaks_cells(conn) &&
               conn->state == OR_CONN_STATE_OPEN &&
               token_bucket_rw_get_write(&TO_OR_CONN(conn)->bucket) <= 0) {
      reason = "connection write bucket exhausted. Pausing.";
      is_global = false;
    } else
      return; /* all good, no need to stop it */
  
    LOG_FN_CONN(conn, (LOG_DEBUG, LD_NET, "%s", reason));
    connection_write_bw_exhausted(conn, is_global);
  }
  
  /** Initialize the global buckets to the values configured in the
   * options */
  void
  connection_bucket_init(void)
  {
    const or_options_t *options = get_options();
    const uint32_t now_ts = monotime_coarse_get_stamp();
    token_bucket_rw_init(&global_bucket,
                      (int32_t)options->BandwidthRate,
                      (int32_t)options->BandwidthBurst,
                      now_ts);
    if (options->RelayBandwidthRate) {
      token_bucket_rw_init(&global_relayed_bucket,
                        (int32_t)options->RelayBandwidthRate,
                        (int32_t)options->RelayBandwidthBurst,
                        now_ts);
    } else {
      token_bucket_rw_init(&global_relayed_bucket,
                        (int32_t)options->BandwidthRate,
                        (int32_t)options->BandwidthBurst,
                        now_ts);
    }
  
    reenable_blocked_connection_init(options);
  }
  
  /** Update the global connection bucket settings to a new value. */
  void
  connection_bucket_adjust(const or_options_t *options)
  {
    token_bucket_rw_adjust(&global_bucket,
                        (int32_t)options->BandwidthRate,
                        (int32_t)options->BandwidthBurst);
    if (options->RelayBandwidthRate) {
      token_bucket_rw_adjust(&global_relayed_bucket,
                          (int32_t)options->RelayBandwidthRate,
                          (int32_t)options->RelayBandwidthBurst);
    } else {
      token_bucket_rw_adjust(&global_relayed_bucket,
                          (int32_t)options->BandwidthRate,
                          (int32_t)options->BandwidthBurst);
    }
  }
  
  /**
   * Cached value of the last coarse-timestamp when we refilled the
   * global buckets.
   */
  static uint32_t last_refilled_global_buckets_ts=0;
  /**
   * Refill the token buckets for a single connection <b>conn</b>, and the
   * global token buckets as appropriate.  Requires that <b>now_ts</b> is
   * the time in coarse timestamp units.
   */
  static void
  connection_bucket_refill_single(connection_t *conn, uint32_t now_ts)
  {
    /* Note that we only check for equality here: the underlying
     * token bucket functions can handle moving backwards in time if they
     * need to. */
    if (now_ts != last_refilled_global_buckets_ts) {
      token_bucket_rw_refill(&global_bucket, now_ts);
      token_bucket_rw_refill(&global_relayed_bucket, now_ts);
      last_refilled_global_buckets_ts = now_ts;
    }
  
    if (connection_speaks_cells(conn) && conn->state == OR_CONN_STATE_OPEN) {
      or_connection_t *or_conn = TO_OR_CONN(conn);
      token_bucket_rw_refill(&or_conn->bucket, now_ts);
    }
  }
  
  /**
   * Event to re-enable all connections that were previously blocked on read or
   * write.
   */
  static mainloop_event_t *reenable_blocked_connections_ev = NULL;
  
  /** True iff reenable_blocked_connections_ev is currently scheduled. */
  static int reenable_blocked_connections_is_scheduled = 0;
  
  /** Delay after which to run reenable_blocked_connections_ev. */
  static struct timeval reenable_blocked_connections_delay;
  
  /**
   * Re-enable all connections that were previously blocked on read or write.
   * This event is scheduled after enough time has elapsed to be sure
   * that the buckets will refill when the connections have something to do.
   */
  static void
  reenable_blocked_connections_cb(mainloop_event_t *ev, void *arg)
  {
    (void)ev;
    (void)arg;
    SMARTLIST_FOREACH_BEGIN(get_connection_array(), connection_t *, conn) {
      if (conn->read_blocked_on_bw == 1) {
        connection_start_reading(conn);
        conn->read_blocked_on_bw = 0;
      }
      if (conn->write_blocked_on_bw == 1) {
        connection_start_writing(conn);
        conn->write_blocked_on_bw = 0;
      }
    } SMARTLIST_FOREACH_END(conn);
  
    reenable_blocked_connections_is_scheduled = 0;
  }
  
  /**
   * Initialize the mainloop event that we use to wake up connections that
   * find themselves blocked on bandwidth.
   */
  static void
  reenable_blocked_connection_init(const or_options_t *options)
  {
    if (! reenable_blocked_connections_ev) {
      reenable_blocked_connections_ev =
        mainloop_event_new(reenable_blocked_connections_cb, NULL);
      reenable_blocked_connections_is_scheduled = 0;
    }
    time_t sec = options->TokenBucketRefillInterval / 1000;
    int msec = (options->TokenBucketRefillInterval % 1000);
    reenable_blocked_connections_delay.tv_sec = sec;
    reenable_blocked_connections_delay.tv_usec = msec * 1000;
  }
  
  /**
   * Called when we have blocked a connection for being low on bandwidth:
   * schedule an event to reenable such connections, if it is not already
   * scheduled.
   */
  static void
  reenable_blocked_connection_schedule(void)
  {
    if (reenable_blocked_connections_is_scheduled)
      return;
    if (BUG(reenable_blocked_connections_ev == NULL)) {
      reenable_blocked_connection_init(get_options());
    }
    mainloop_event_schedule(reenable_blocked_connections_ev,
                            &reenable_blocked_connections_delay);
    reenable_blocked_connections_is_scheduled = 1;
  }
  
  /** Read bytes from conn-\>s and process them.
   *
   * It calls connection_buf_read_from_socket() to bring in any new bytes,
   * and then calls connection_process_inbuf() to process them.
   *
   * Mark the connection and return -1 if you want to close it, else
   * return 0.
   */
  static int
  connection_handle_read_impl(connection_t *conn)
  {
    ssize_t max_to_read=-1, try_to_read;
    size_t before, n_read = 0;
    int socket_error = 0;
  
    if (conn->marked_for_close)
      return 0; /* do nothing */
  
    conn->timestamp_last_read_allowed = approx_time();
  
    connection_bucket_refill_single(conn, monotime_coarse_get_stamp());
  
    switch (conn->type) {
      case CONN_TYPE_OR_LISTENER:
        return connection_handle_listener_read(conn, CONN_TYPE_OR);
      case CONN_TYPE_EXT_OR_LISTENER:
        return connection_handle_listener_read(conn, CONN_TYPE_EXT_OR);
      case CONN_TYPE_AP_LISTENER:
      case CONN_TYPE_AP_TRANS_LISTENER:
      case CONN_TYPE_AP_NATD_LISTENER:
      case CONN_TYPE_AP_HTTP_CONNECT_LISTENER:
        return connection_handle_listener_read(conn, CONN_TYPE_AP);
      case CONN_TYPE_DIR_LISTENER:
        return connection_handle_listener_read(conn, CONN_TYPE_DIR);
      case CONN_TYPE_CONTROL_LISTENER:
        return connection_handle_listener_read(conn, CONN_TYPE_CONTROL);
      case CONN_TYPE_AP_DNS_LISTENER:
        /* This should never happen; eventdns.c handles the reads here. */
        tor_fragile_assert();
        return 0;
    }
  
   loop_again:
    try_to_read = max_to_read;
    tor_assert(!conn->marked_for_close);
  
    before = buf_datalen(conn->inbuf);
    if (connection_buf_read_from_socket(conn, &max_to_read, &socket_error) < 0) {
      /* There's a read error; kill the connection.*/
      if (conn->type == CONN_TYPE_OR) {
        connection_or_notify_error(TO_OR_CONN(conn),
                                   socket_error != 0 ?
                                     errno_to_orconn_end_reason(socket_error) :
                                     END_OR_CONN_REASON_CONNRESET,
                                   socket_error != 0 ?
                                     tor_socket_strerror(socket_error) :
                                     "(unknown, errno was 0)");
      }
      if (CONN_IS_EDGE(conn)) {
        edge_connection_t *edge_conn = TO_EDGE_CONN(conn);
        connection_edge_end_errno(edge_conn);
        if (conn->type == CONN_TYPE_AP && TO_ENTRY_CONN(conn)->socks_request) {
          /* broken, don't send a socks reply back */
          TO_ENTRY_CONN(conn)->socks_request->has_finished = 1;
        }
      }
      connection_close_immediate(conn); /* Don't flush; connection is dead. */
      /*
       * This can bypass normal channel checking since we did
       * connection_or_notify_error() above.
       */
      connection_mark_for_close_internal(conn);
      return -1;
    }
    n_read += buf_datalen(conn->inbuf) - before;
    if (CONN_IS_EDGE(conn) && try_to_read != max_to_read) {
      /* instruct it not to try to package partial cells. */
      if (connection_process_inbuf(conn, 0) < 0) {
        return -1;
      }
      if (!conn->marked_for_close &&
          connection_is_reading(conn) &&
          !conn->inbuf_reached_eof &&
          max_to_read > 0)
        goto loop_again; /* try reading again, in case more is here now */
    }
    /* one last try, packaging partial cells and all. */
    if (!conn->marked_for_close &&
        connection_process_inbuf(conn, 1) < 0) {
      return -1;
    }
    if (conn->linked_conn) {
      /* The other side's handle_write() will never actually get called, so
       * we need to invoke the appropriate callbacks ourself. */
      connection_t *linked = conn->linked_conn;
  
      if (n_read) {
        /* Probably a no-op, since linked conns typically don't count for
         * bandwidth rate limiting. But do it anyway so we can keep stats
         * accurately. Note that since we read the bytes from conn, and
         * we're writing the bytes onto the linked connection, we count
         * these as <i>written</i> bytes. */
        connection_buckets_decrement(linked, approx_time(), 0, n_read);
  
        if (connection_flushed_some(linked) < 0)
          connection_mark_for_close(linked);
        if (!connection_wants_to_flush(linked))
          connection_finished_flushing(linked);
      }
  
      if (!buf_datalen(linked->outbuf) && conn->active_on_link)
        connection_stop_reading_from_linked_conn(conn);
    }
    /* If we hit the EOF, call connection_reached_eof(). */
    if (!conn->marked_for_close &&
        conn->inbuf_reached_eof &&
        connection_reached_eof(conn) < 0) {
      return -1;
    }
    return 0;
  }
  
  /* DOCDOC connection_handle_read */
  int
  connection_handle_read(connection_t *conn)
  {
    int res;
    update_current_time(time(NULL));
    res = connection_handle_read_impl(conn);
    return res;
  }
  
  /** Pull in new bytes from conn-\>s or conn-\>linked_conn onto conn-\>inbuf,
   * either directly or via TLS. Reduce the token buckets by the number of bytes
   * read.
   *
   * If *max_to_read is -1, then decide it ourselves, else go with the
   * value passed to us. When returning, if it's changed, subtract the
   * number of bytes we read from *max_to_read.
   *
   * Return -1 if we want to break conn, else return 0.
   */
  static int
  connection_buf_read_from_socket(connection_t *conn, ssize_t *max_to_read,
                         int *socket_error)
  {
    int result;
    ssize_t at_most = *max_to_read;
    size_t slack_in_buf, more_to_read;
    size_t n_read = 0, n_written = 0;
  
    if (at_most == -1) { /* we need to initialize it */
      /* how many bytes are we allowed to read? */
      at_most = connection_bucket_read_limit(conn, approx_time());
    }
  
    slack_in_buf = buf_slack(conn->inbuf);
   again:
    if ((size_t)at_most > slack_in_buf && slack_in_buf >= 1024) {
      more_to_read = at_most - slack_in_buf;
      at_most = slack_in_buf;
    } else {
      more_to_read = 0;
    }
  
    if (connection_speaks_cells(conn) &&
        conn->state > OR_CONN_STATE_PROXY_HANDSHAKING) {
      int pending;
      or_connection_t *or_conn = TO_OR_CONN(conn);
      size_t initial_size;
      if (conn->state == OR_CONN_STATE_TLS_HANDSHAKING ||
          conn->state == OR_CONN_STATE_TLS_CLIENT_RENEGOTIATING) {
        /* continue handshaking even if global token bucket is empty */
        return connection_tls_continue_handshake(or_conn);
      }
  
      log_debug(LD_NET,
                "%d: starting, inbuf_datalen %ld (%d pending in tls object)."
                " at_most %ld.",
                (int)conn->s,(long)buf_datalen(conn->inbuf),
                tor_tls_get_pending_bytes(or_conn->tls), (long)at_most);
  
      initial_size = buf_datalen(conn->inbuf);
      /* else open, or closing */
      result = buf_read_from_tls(conn->inbuf, or_conn->tls, at_most);
      if (TOR_TLS_IS_ERROR(result) || result == TOR_TLS_CLOSE)
        or_conn->tls_error = result;
      else
        or_conn->tls_error = 0;
  
      switch (result) {
        case TOR_TLS_CLOSE:
        case TOR_TLS_ERROR_IO:
          log_debug(LD_NET,"TLS connection closed %son read. Closing. "
                   "(Nickname %s, address %s)",
                   result == TOR_TLS_CLOSE ? "cleanly " : "",
                   or_conn->nickname ? or_conn->nickname : "not set",
                   conn->address);
          return result;
        CASE_TOR_TLS_ERROR_ANY_NONIO:
          log_debug(LD_NET,"tls error [%s]. breaking (nickname %s, address %s).",
                   tor_tls_err_to_string(result),
                   or_conn->nickname ? or_conn->nickname : "not set",
                   conn->address);
          return result;
        case TOR_TLS_WANTWRITE:
          connection_start_writing(conn);
          return 0;
        case TOR_TLS_WANTREAD:
          if (conn->in_connection_handle_write) {
            /* We've been invoked from connection_handle_write, because we're
             * waiting for a TLS renegotiation, the renegotiation started, and
             * SSL_read returned WANTWRITE.  But now SSL_read is saying WANTREAD
             * again.  Stop waiting for write events now, or else we'll
             * busy-loop until data arrives for us to read.
             * XXX: remove this when v2 handshakes support is dropped. */
            connection_stop_writing(conn);
            if (!connection_is_reading(conn))
              connection_start_reading(conn);
          }
          /* we're already reading, one hopes */
          break;
        case TOR_TLS_DONE: /* no data read, so nothing to process */
          break; /* so we call bucket_decrement below */
        default:
          break;
      }
      pending = tor_tls_get_pending_bytes(or_conn->tls);
      if (pending) {
        /* If we have any pending bytes, we read them now.  This *can*
         * take us over our read allotment, but really we shouldn't be
         * believing that SSL bytes are the same as TCP bytes anyway. */
        int r2 = buf_read_from_tls(conn->inbuf, or_conn->tls, pending);
        if (BUG(r2<0)) {
          log_warn(LD_BUG, "apparently, reading pending bytes can fail.");
          return -1;
        }
      }
      result = (int)(buf_datalen(conn->inbuf)-initial_size);
      tor_tls_get_n_raw_bytes(or_conn->tls, &n_read, &n_written);
      log_debug(LD_GENERAL, "After TLS read of %d: %ld read, %ld written",
                result, (long)n_read, (long)n_written);
    } else if (conn->linked) {
      if (conn->linked_conn) {
        result = buf_move_to_buf(conn->inbuf, conn->linked_conn->outbuf,
                                 &conn->linked_conn->outbuf_flushlen);
        if (BUG(result<0)) {
          log_warn(LD_BUG, "reading from linked connection buffer failed.");
          return -1;
        }
      } else {
        result = 0;
      }
      //log_notice(LD_GENERAL, "Moved %d bytes on an internal link!", result);
      /* If the other side has disappeared, or if it's been marked for close and
       * we flushed its outbuf, then we should set our inbuf_reached_eof. */
      if (!conn->linked_conn ||
          (conn->linked_conn->marked_for_close &&
           buf_datalen(conn->linked_conn->outbuf) == 0))
        conn->inbuf_reached_eof = 1;
  
      n_read = (size_t) result;
    } else {
      /* !connection_speaks_cells, !conn->linked_conn. */
      int reached_eof = 0;
      CONN_LOG_PROTECT(conn,
                       result = buf_read_from_socket(conn->inbuf, conn->s,
                                                     at_most,
                                                     &reached_eof,
                                                     socket_error));
      if (reached_eof)
        conn->inbuf_reached_eof = 1;
  
  //  log_fn(LOG_DEBUG,"read_to_buf returned %d.",read_result);
  
      if (result < 0)
        return -1;
      n_read = (size_t) result;
    }
  
    if (n_read > 0) {
       /* change *max_to_read */
      *max_to_read = at_most - n_read;
  
      /* Update edge_conn->n_read */
      if (conn->type == CONN_TYPE_AP) {
        edge_connection_t *edge_conn = TO_EDGE_CONN(conn);
  
        /* Check for overflow: */
        if (PREDICT_LIKELY(UINT32_MAX - edge_conn->n_read > n_read))
          edge_conn->n_read += (int)n_read;
        else
          edge_conn->n_read = UINT32_MAX;
      }
  
      /* If CONN_BW events are enabled, update conn->n_read_conn_bw for
       * OR/DIR/EXIT connections, checking for overflow. */
      if (get_options()->TestingEnableConnBwEvent &&
         (conn->type == CONN_TYPE_OR ||
          conn->type == CONN_TYPE_DIR ||
          conn->type == CONN_TYPE_EXIT)) {
        if (PREDICT_LIKELY(UINT32_MAX - conn->n_read_conn_bw > n_read))
          conn->n_read_conn_bw += (int)n_read;
        else
          conn->n_read_conn_bw = UINT32_MAX;
      }
    }
  
    connection_buckets_decrement(conn, approx_time(), n_read, n_written);
  
    if (more_to_read && result == at_most) {
      slack_in_buf = buf_slack(conn->inbuf);
      at_most = more_to_read;
      goto again;
    }
  
    /* Call even if result is 0, since the global read bucket may
     * have reached 0 on a different conn, and this connection needs to
     * know to stop reading. */
    connection_consider_empty_read_buckets(conn);
    if (n_written > 0 && connection_is_writing(conn))
      connection_consider_empty_write_buckets(conn);
  
    return 0;
  }
  
  /** A pass-through to fetch_from_buf. */
  int
  connection_buf_get_bytes(char *string, size_t len, connection_t *conn)
  {
    return buf_get_bytes(conn->inbuf, string, len);
  }
  
  /** As buf_get_line(), but read from a connection's input buffer. */
  int
  connection_buf_get_line(connection_t *conn, char *data,
                                 size_t *data_len)
  {
    return buf_get_line(conn->inbuf, data, data_len);
  }
  
  /** As fetch_from_buf_http, but fetches from a connection's input buffer_t as
   * appropriate. */
  int
  connection_fetch_from_buf_http(connection_t *conn,
                                 char **headers_out, size_t max_headerlen,
                                 char **body_out, size_t *body_used,
                                 size_t max_bodylen, int force_complete)
  {
    return fetch_from_buf_http(conn->inbuf, headers_out, max_headerlen,
                               body_out, body_used, max_bodylen, force_complete);
  }
  
  /** Return conn-\>outbuf_flushlen: how many bytes conn wants to flush
   * from its outbuf. */
  int
  connection_wants_to_flush(connection_t *conn)
  {
    return conn->outbuf_flushlen > 0;
  }
  
  /** Are there too many bytes on edge connection <b>conn</b>'s outbuf to
   * send back a relay-level sendme yet? Return 1 if so, 0 if not. Used by
   * connection_edge_consider_sending_sendme().
   */
  int
  connection_outbuf_too_full(connection_t *conn)
  {
    return (conn->outbuf_flushlen > 10*CELL_PAYLOAD_SIZE);
  }
  
  /**
   * On Windows Vista and Windows 7, tune the send buffer size according to a
   * hint from the OS.
   *
   * This should help fix slow upload rates.
   */
  static void
  update_send_buffer_size(tor_socket_t sock)
  {
  #ifdef _WIN32
    /* We only do this on Vista and 7, because earlier versions of Windows
     * don't have the SIO_IDEAL_SEND_BACKLOG_QUERY functionality, and on
     * later versions it isn't necessary. */
    static int isVistaOr7 = -1;
    if (isVistaOr7 == -1) {
      isVistaOr7 = 0;
      OSVERSIONINFO osvi = { 0 };
      osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
      GetVersionEx(&osvi);
      if (osvi.dwMajorVersion == 6 && osvi.dwMinorVersion < 2)
        isVistaOr7 = 1;
    }
    if (!isVistaOr7)
      return;
    if (get_options()->ConstrainedSockets)
      return;
    ULONG isb = 0;
    DWORD bytesReturned = 0;
    if (!WSAIoctl(sock, SIO_IDEAL_SEND_BACKLOG_QUERY, NULL, 0,
        &isb, sizeof(isb), &bytesReturned, NULL, NULL)) {
      setsockopt(sock, SOL_SOCKET, SO_SNDBUF, (const char*)&isb, sizeof(isb));
    }
  #else
    (void) sock;
  #endif
  }
  
  /** Try to flush more bytes onto <b>conn</b>-\>s.
   *
   * This function is called in connection_handle_write(), which gets
   * called from conn_write_callback() in main.c when libevent tells us
   * that <b>conn</b> wants to write.
   *
   * Update <b>conn</b>-\>timestamp_last_write_allowed to now, and call flush_buf
   * or flush_buf_tls appropriately. If it succeeds and there are no more
   * more bytes on <b>conn</b>-\>outbuf, then call connection_finished_flushing
   * on it too.
   *
   * If <b>force</b>, then write as many bytes as possible, ignoring bandwidth
   * limits.  (Used for flushing messages to controller connections on fatal
   * errors.)
   *
   * Mark the connection and return -1 if you want to close it, else
   * return 0.
   */
  static int
  connection_handle_write_impl(connection_t *conn, int force)
  {
    int e;
    socklen_t len=(socklen_t)sizeof(e);
    int result;
    ssize_t max_to_write;
    time_t now = approx_time();
    size_t n_read = 0, n_written = 0;
    int dont_stop_writing = 0;
  
    tor_assert(!connection_is_listener(conn));
  
    if (conn->marked_for_close || !SOCKET_OK(conn->s))
      return 0; /* do nothing */
  
    if (conn->in_flushed_some) {
      log_warn(LD_BUG, "called recursively from inside conn->in_flushed_some");
      return 0;
    }
  
    conn->timestamp_last_write_allowed = now;
  
    connection_bucket_refill_single(conn, monotime_coarse_get_stamp());
  
    /* Sometimes, "writable" means "connected". */
    if (connection_state_is_connecting(conn)) {
      if (getsockopt(conn->s, SOL_SOCKET, SO_ERROR, (void*)&e, &len) < 0) {
        log_warn(LD_BUG, "getsockopt() syscall failed");
        if (conn->type == CONN_TYPE_OR) {
          or_connection_t *orconn = TO_OR_CONN(conn);
          connection_or_close_for_error(orconn, 0);
        } else {
          if (CONN_IS_EDGE(conn)) {
            connection_edge_end_errno(TO_EDGE_CONN(conn));
          }
          connection_mark_for_close(conn);
        }
        return -1;
      }
      if (e) {
        /* some sort of error, but maybe just inprogress still */
        if (!ERRNO_IS_CONN_EINPROGRESS(e)) {
          log_info(LD_NET,"in-progress connect failed. Removing. (%s)",
                   tor_socket_strerror(e));
          if (CONN_IS_EDGE(conn))
            connection_edge_end_errno(TO_EDGE_CONN(conn));
          if (conn->type == CONN_TYPE_OR)
            connection_or_notify_error(TO_OR_CONN(conn),
                                       errno_to_orconn_end_reason(e),
                                       tor_socket_strerror(e));
  
          connection_close_immediate(conn);
          /*
           * This can bypass normal channel checking since we did
           * connection_or_notify_error() above.
           */
          connection_mark_for_close_internal(conn);
          return -1;
        } else {
          return 0; /* no change, see if next time is better */
        }
      }
      /* The connection is successful. */
      if (connection_finished_connecting(conn)<0)
        return -1;
    }
  
    max_to_write = force ? (ssize_t)conn->outbuf_flushlen
      : connection_bucket_write_limit(conn, now);
  
    if (connection_speaks_cells(conn) &&
        conn->state > OR_CONN_STATE_PROXY_HANDSHAKING) {
      or_connection_t *or_conn = TO_OR_CONN(conn);
      size_t initial_size;
      if (conn->state == OR_CONN_STATE_TLS_HANDSHAKING ||
          conn->state == OR_CONN_STATE_TLS_CLIENT_RENEGOTIATING) {
        connection_stop_writing(conn);
        if (connection_tls_continue_handshake(or_conn) < 0) {
          /* Don't flush; connection is dead. */
          connection_or_notify_error(or_conn,
                                     END_OR_CONN_REASON_MISC,
                                     "TLS error in connection_tls_"
                                     "continue_handshake()");
          connection_close_immediate(conn);
          /*
           * This can bypass normal channel checking since we did
           * connection_or_notify_error() above.
           */
          connection_mark_for_close_internal(conn);
          return -1;
        }
        return 0;
      } else if (conn->state == OR_CONN_STATE_TLS_SERVER_RENEGOTIATING) {
        return connection_handle_read(conn);
      }
  
      /* else open, or closing */
      initial_size = buf_datalen(conn->outbuf);
      result = buf_flush_to_tls(conn->outbuf, or_conn->tls,
                             max_to_write, &conn->outbuf_flushlen);
  
      if (result >= 0)
        update_send_buffer_size(conn->s);
  
      /* If we just flushed the last bytes, tell the channel on the
       * or_conn to check if it needs to geoip_change_dirreq_state() */
      /* XXXX move this to flushed_some or finished_flushing -NM */
      if (buf_datalen(conn->outbuf) == 0 && or_conn->chan)
        channel_notify_flushed(TLS_CHAN_TO_BASE(or_conn->chan));
  
      switch (result) {
        CASE_TOR_TLS_ERROR_ANY:
        case TOR_TLS_CLOSE:
          log_info(LD_NET, result != TOR_TLS_CLOSE ?
                   "tls error. breaking.":"TLS connection closed on flush");
          /* Don't flush; connection is dead. */
          connection_or_notify_error(or_conn,
                                     END_OR_CONN_REASON_MISC,
                                     result != TOR_TLS_CLOSE ?
                                       "TLS error in during flush" :
                                       "TLS closed during flush");
          connection_close_immediate(conn);
          /*
           * This can bypass normal channel checking since we did
           * connection_or_notify_error() above.
           */
          connection_mark_for_close_internal(conn);
          return -1;
        case TOR_TLS_WANTWRITE:
          log_debug(LD_NET,"wanted write.");
          /* we're already writing */
          dont_stop_writing = 1;
          break;
        case TOR_TLS_WANTREAD:
          /* Make sure to avoid a loop if the receive buckets are empty. */
          log_debug(LD_NET,"wanted read.");
          if (!connection_is_reading(conn)) {
            connection_write_bw_exhausted(conn, true);
            /* we'll start reading again when we get more tokens in our
             * read bucket; then we'll start writing again too.
             */
          }
          /* else no problem, we're already reading */
          return 0;
        /* case TOR_TLS_DONE:
         * for TOR_TLS_DONE, fall through to check if the flushlen
         * is empty, so we can stop writing.
         */
      }
  
      tor_tls_get_n_raw_bytes(or_conn->tls, &n_read, &n_written);
      log_debug(LD_GENERAL, "After TLS write of %d: %ld read, %ld written",
                result, (long)n_read, (long)n_written);
      or_conn->bytes_xmitted += result;
      or_conn->bytes_xmitted_by_tls += n_written;
      /* So we notice bytes were written even on error */
      /* XXXX This cast is safe since we can never write INT_MAX bytes in a
       * single set of TLS operations. But it looks kinda ugly. If we refactor
       * the *_buf_tls functions, we should make them return ssize_t or size_t
       * or something. */
      result = (int)(initial_size-buf_datalen(conn->outbuf));
    } else {
      CONN_LOG_PROTECT(conn,
                       result = buf_flush_to_socket(conn->outbuf, conn->s,
                                          max_to_write, &conn->outbuf_flushlen));
      if (result < 0) {
        if (CONN_IS_EDGE(conn))
          connection_edge_end_errno(TO_EDGE_CONN(conn));
        if (conn->type == CONN_TYPE_AP) {
          /* writing failed; we couldn't send a SOCKS reply if we wanted to */
          TO_ENTRY_CONN(conn)->socks_request->has_finished = 1;
        }
  
        connection_close_immediate(conn); /* Don't flush; connection is dead. */
        connection_mark_for_close(conn);
        return -1;
      }
      update_send_buffer_size(conn->s);
      n_written = (size_t) result;
    }
  
    if (n_written && conn->type == CONN_TYPE_AP) {
      edge_connection_t *edge_conn = TO_EDGE_CONN(conn);
  
      /* Check for overflow: */
      if (PREDICT_LIKELY(UINT32_MAX - edge_conn->n_written > n_written))
        edge_conn->n_written += (int)n_written;
      else
        edge_conn->n_written = UINT32_MAX;
    }
  
    /* If CONN_BW events are enabled, update conn->n_written_conn_bw for
     * OR/DIR/EXIT connections, checking for overflow. */
    if (n_written && get_options()->TestingEnableConnBwEvent &&
       (conn->type == CONN_TYPE_OR ||
        conn->type == CONN_TYPE_DIR ||
        conn->type == CONN_TYPE_EXIT)) {
      if (PREDICT_LIKELY(UINT32_MAX - conn->n_written_conn_bw > n_written))
        conn->n_written_conn_bw += (int)n_written;
      else
        conn->n_written_conn_bw = UINT32_MAX;
    }
  
    connection_buckets_decrement(conn, approx_time(), n_read, n_written);
  
    if (result > 0) {
      /* If we wrote any bytes from our buffer, then call the appropriate
       * functions. */
      if (connection_flushed_some(conn) < 0) {
        if (connection_speaks_cells(conn)) {
          connection_or_notify_error(TO_OR_CONN(conn),
                                     END_OR_CONN_REASON_MISC,
                                     "Got error back from "
                                     "connection_flushed_some()");
        }
  
        /*
         * This can bypass normal channel checking since we did
         * connection_or_notify_error() above.
         */
        connection_mark_for_close_internal(conn);
      }
    }
  
    if (!connection_wants_to_flush(conn) &&
        !dont_stop_writing) { /* it's done flushing */
      if (connection_finished_flushing(conn) < 0) {
        /* already marked */
        return -1;
      }
      return 0;
    }
  
    /* Call even if result is 0, since the global write bucket may
     * have reached 0 on a different conn, and this connection needs to
     * know to stop writing. */
    connection_consider_empty_write_buckets(conn);
    if (n_read > 0 && connection_is_reading(conn))
      connection_consider_empty_read_buckets(conn);
  
    return 0;
  }
  
  /* DOCDOC connection_handle_write */
  int
  connection_handle_write(connection_t *conn, int force)
  {
      int res;
      update_current_time(time(NULL));
      /* connection_handle_write_impl() might call connection_handle_read()
       * if we're in the middle of a v2 handshake, in which case it needs this
       * flag set. */
      conn->in_connection_handle_write = 1;
      res = connection_handle_write_impl(conn, force);
      conn->in_connection_handle_write = 0;
      return res;
  }
  
  /**
   * Try to flush data that's waiting for a write on <b>conn</b>.  Return
   * -1 on failure, 0 on success.
   *
   * Don't use this function for regular writing; the buffers
   * system should be good enough at scheduling writes there.  Instead, this
   * function is for cases when we're about to exit or something and we want
   * to report it right away.
   */
  int
  connection_flush(connection_t *conn)
  {
    return connection_handle_write(conn, 1);
  }
  
  /** Helper for connection_write_to_buf_impl and connection_write_buf_to_buf:
   *
   * Return true iff it is okay to queue bytes on <b>conn</b>'s outbuf for
   * writing.
   */
  static int
  connection_may_write_to_buf(connection_t *conn)
  {
    /* if it's marked for close, only allow write if we mean to flush it */
    if (conn->marked_for_close && !conn->hold_open_until_flushed)
      return 0;
  
    return 1;
  }
  
  /** Helper for connection_write_to_buf_impl and connection_write_buf_to_buf:
   *
   * Called when an attempt to add bytes on <b>conn</b>'s outbuf has failed;
   * mark the connection and warn as appropriate.
   */
  static void
  connection_write_to_buf_failed(connection_t *conn)
  {
    if (CONN_IS_EDGE(conn)) {
      /* if it failed, it means we have our package/delivery windows set
         wrong compared to our max outbuf size. close the whole circuit. */
      log_warn(LD_NET,
               "write_to_buf failed. Closing circuit (fd %d).", (int)conn->s);
      circuit_mark_for_close(circuit_get_by_edge_conn(TO_EDGE_CONN(conn)),
                             END_CIRC_REASON_INTERNAL);
    } else if (conn->type == CONN_TYPE_OR) {
      or_connection_t *orconn = TO_OR_CONN(conn);
      log_warn(LD_NET,
               "write_to_buf failed on an orconn; notifying of error "
               "(fd %d)", (int)(conn->s));
      connection_or_close_for_error(orconn, 0);
    } else {
      log_warn(LD_NET,
               "write_to_buf failed. Closing connection (fd %d).",
               (int)conn->s);
      connection_mark_for_close(conn);
    }
  }
  
  /** Helper for connection_write_to_buf_impl and connection_write_buf_to_buf:
   *
   * Called when an attempt to add bytes on <b>conn</b>'s outbuf has succeeded:
   * record the number of bytes added.
   */
  static void
  connection_write_to_buf_commit(connection_t *conn, size_t len)
  {
    /* If we receive optimistic data in the EXIT_CONN_STATE_RESOLVING
     * state, we don't want to try to write it right away, since
     * conn->write_event won't be set yet.  Otherwise, write data from
     * this conn as the socket is available. */
    if (conn->write_event) {
      connection_start_writing(conn);
    }
    conn->outbuf_flushlen += len;
  }
  
  /** Append <b>len</b> bytes of <b>string</b> onto <b>conn</b>'s
   * outbuf, and ask it to start writing.
   *
   * If <b>zlib</b> is nonzero, this is a directory connection that should get
   * its contents compressed or decompressed as they're written.  If zlib is
   * negative, this is the last data to be compressed, and the connection's zlib
   * state should be flushed.
   */
  MOCK_IMPL(void,
  connection_write_to_buf_impl_,(const char *string, size_t len,
                                 connection_t *conn, int zlib))
  {
    /* XXXX This function really needs to return -1 on failure. */
    int r;
    if (!len && !(zlib<0))
      return;
  
    if (!connection_may_write_to_buf(conn))
      return;
  
    size_t written;
  
    if (zlib) {
      size_t old_datalen = buf_datalen(conn->outbuf);
      dir_connection_t *dir_conn = TO_DIR_CONN(conn);
      int done = zlib < 0;
      CONN_LOG_PROTECT(conn, r = buf_add_compress(conn->outbuf,
                                                  dir_conn->compress_state,
                                                  string, len, done));
      written = buf_datalen(conn->outbuf) - old_datalen;
    } else {
      CONN_LOG_PROTECT(conn, r = buf_add(conn->outbuf, string, len));
      written = len;
    }
    if (r < 0) {
      connection_write_to_buf_failed(conn);
      return;
    }
    connection_write_to_buf_commit(conn, written);
  }
  
  void
  connection_buf_add_compress(const char *string, size_t len,
                              dir_connection_t *conn, int done)
  {
    connection_write_to_buf_impl_(string, len, TO_CONN(conn), done ? -1 : 1);
  }
  
  /**
   * Add all bytes from <b>buf</b> to <b>conn</b>'s outbuf, draining them
   * from <b>buf</b>. (If the connection is marked and will soon be closed,
   * nothing is drained.)
   */
  void
  connection_buf_add_buf(connection_t *conn, buf_t *buf)
  {
    tor_assert(conn);
    tor_assert(buf);
    size_t len = buf_datalen(buf);
    if (len == 0)
      return;
  
    if (!connection_may_write_to_buf(conn))
      return;
  
    buf_move_all(conn->outbuf, buf);
    connection_write_to_buf_commit(conn, len);
  }
  
  #define CONN_GET_ALL_TEMPLATE(var, test) \
    STMT_BEGIN \
      smartlist_t *conns = get_connection_array();   \
      smartlist_t *ret_conns = smartlist_new();     \
      SMARTLIST_FOREACH_BEGIN(conns, connection_t *, var) { \
        if (var && (test) && !var->marked_for_close) \
          smartlist_add(ret_conns, var); \
      } SMARTLIST_FOREACH_END(var);                                            \
      return ret_conns; \
    STMT_END
  
  /* Return a list of connections that aren't close and matches the given type
   * and state. The returned list can be empty and must be freed using
   * smartlist_free(). The caller does NOT have ownership of the objects in the
   * list so it must not free them nor reference them as they can disappear. */
  smartlist_t *
  connection_list_by_type_state(int type, int state)
  {
    CONN_GET_ALL_TEMPLATE(conn, (conn->type == type && conn->state == state));
  }
  
  /* Return a list of connections that aren't close and matches the given type
   * and purpose. The returned list can be empty and must be freed using
   * smartlist_free(). The caller does NOT have ownership of the objects in the
   * list so it must not free them nor reference them as they can disappear. */
  smartlist_t *
  connection_list_by_type_purpose(int type, int purpose)
  {
    CONN_GET_ALL_TEMPLATE(conn,
                          (conn->type == type && conn->purpose == purpose));
  }
  
  /** Return a connection_t * from get_connection_array() that satisfies test on
   * var, and that is not marked for close. */
  #define CONN_GET_TEMPLATE(var, test)               \
    STMT_BEGIN                                       \
      smartlist_t *conns = get_connection_array();   \
      SMARTLIST_FOREACH(conns, connection_t *, var,  \
      {                                              \
        if (var && (test) && !var->marked_for_close) \
          return var;                                \
      });                                            \
      return NULL;                                   \
    STMT_END
  
  /** Return a connection with given type, address, port, and purpose;
   * or NULL if no such connection exists (or if all such connections are marked
   * for close). */
  MOCK_IMPL(connection_t *,
  connection_get_by_type_addr_port_purpose,(int type,
                                           const tor_addr_t *addr, uint16_t port,
                                           int purpose))
  {
    CONN_GET_TEMPLATE(conn,
         (conn->type == type &&
          tor_addr_eq(&conn->addr, addr) &&
          conn->port == port &&
          conn->purpose == purpose));
  }
  
  /** Return the stream with id <b>id</b> if it is not already marked for
   * close.
   */
  connection_t *
  connection_get_by_global_id(uint64_t id)
  {
    CONN_GET_TEMPLATE(conn, conn->global_identifier == id);
  }
  
  /** Return a connection of type <b>type</b> that is not marked for close.
   */
  connection_t *
  connection_get_by_type(int type)
  {
    CONN_GET_TEMPLATE(conn, conn->type == type);
  }
  
  /** Return a connection of type <b>type</b> that is in state <b>state</b>,
   * and that is not marked for close.
   */
  connection_t *
  connection_get_by_type_state(int type, int state)
  {
    CONN_GET_TEMPLATE(conn, conn->type == type && conn->state == state);
  }
  
  /** Return a connection of type <b>type</b> that has rendquery equal
   * to <b>rendquery</b>, and that is not marked for close. If state
   * is non-zero, conn must be of that state too.
   */
  connection_t *
  connection_get_by_type_state_rendquery(int type, int state,
                                         const char *rendquery)
  {
    tor_assert(type == CONN_TYPE_DIR ||
               type == CONN_TYPE_AP || type == CONN_TYPE_EXIT);
    tor_assert(rendquery);
  
    CONN_GET_TEMPLATE(conn,
         (conn->type == type &&
          (!state || state == conn->state)) &&
          (
           (type == CONN_TYPE_DIR &&
            TO_DIR_CONN(conn)->rend_data &&
            !rend_cmp_service_ids(rendquery,
                      rend_data_get_address(TO_DIR_CONN(conn)->rend_data)))
           ||
                (CONN_IS_EDGE(conn) &&
                 TO_EDGE_CONN(conn)->rend_data &&
                 !rend_cmp_service_ids(rendquery,
                      rend_data_get_address(TO_EDGE_CONN(conn)->rend_data)))
           ));
  }
  
  /** Return a new smartlist of dir_connection_t * from get_connection_array()
   * that satisfy conn_test on connection_t *conn_var, and dirconn_test on
   * dir_connection_t *dirconn_var. conn_var must be of CONN_TYPE_DIR and not
   * marked for close to be included in the list. */
  #define DIR_CONN_LIST_TEMPLATE(conn_var, conn_test,             \
                                 dirconn_var, dirconn_test)       \
    STMT_BEGIN                                                    \
      smartlist_t *conns = get_connection_array();                \
      smartlist_t *dir_conns = smartlist_new();                   \
      SMARTLIST_FOREACH_BEGIN(conns, connection_t *, conn_var) {  \
        if (conn_var && (conn_test)                               \
            && conn_var->type == CONN_TYPE_DIR                    \
            && !conn_var->marked_for_close) {                     \
          dir_connection_t *dirconn_var = TO_DIR_CONN(conn_var);  \
          if (dirconn_var && (dirconn_test)) {                    \
            smartlist_add(dir_conns, dirconn_var);                \
          }                                                       \
        }                                                         \
      } SMARTLIST_FOREACH_END(conn_var);                          \
      return dir_conns;                                           \
    STMT_END
  
  /** Return a list of directory connections that are fetching the item
   * described by <b>purpose</b>/<b>resource</b>. If there are none,
   * return an empty list. This list must be freed using smartlist_free,
   * but the pointers in it must not be freed.
   * Note that this list should not be cached, as the pointers in it can be
   * freed if their connections close. */
  smartlist_t *
  connection_dir_list_by_purpose_and_resource(
                                              int purpose,
                                              const char *resource)
  {
    DIR_CONN_LIST_TEMPLATE(conn,
                           conn->purpose == purpose,
                           dirconn,
                           0 == strcmp_opt(resource,
                                           dirconn->requested_resource));
  }
  
  /** Return a list of directory connections that are fetching the item
   * described by <b>purpose</b>/<b>resource</b>/<b>state</b>. If there are
   * none, return an empty list. This list must be freed using smartlist_free,
   * but the pointers in it must not be freed.
   * Note that this list should not be cached, as the pointers in it can be
   * freed if their connections close. */
  smartlist_t *
  connection_dir_list_by_purpose_resource_and_state(
                                                    int purpose,
                                                    const char *resource,
                                                    int state)
  {
    DIR_CONN_LIST_TEMPLATE(conn,
                           conn->purpose == purpose && conn->state == state,
                           dirconn,
                           0 == strcmp_opt(resource,
                                           dirconn->requested_resource));
  }
  
  #undef DIR_CONN_LIST_TEMPLATE
  
  /** Return an arbitrary active OR connection that isn't <b>this_conn</b>.
   *
   * We use this to guess if we should tell the controller that we
   * didn't manage to connect to any of our bridges. */
  static connection_t *
  connection_get_another_active_or_conn(const or_connection_t *this_conn)
  {
    CONN_GET_TEMPLATE(conn,
                      conn != TO_CONN(this_conn) && conn->type == CONN_TYPE_OR);
  }
  
  /** Return 1 if there are any active OR connections apart from
   * <b>this_conn</b>.
   *
   * We use this to guess if we should tell the controller that we
   * didn't manage to connect to any of our bridges. */
  int
  any_other_active_or_conns(const or_connection_t *this_conn)
  {
    connection_t *conn = connection_get_another_active_or_conn(this_conn);
    if (conn != NULL) {
      log_debug(LD_DIR, "%s: Found an OR connection: %s",
                __func__, conn->address);
      return 1;
    }
  
    return 0;
  }
  
  #undef CONN_GET_TEMPLATE
  
  /** Return 1 if <b>conn</b> is a listener conn, else return 0. */
  int
  connection_is_listener(connection_t *conn)
  {
    if (conn->type == CONN_TYPE_OR_LISTENER ||
        conn->type == CONN_TYPE_EXT_OR_LISTENER ||
        conn->type == CONN_TYPE_AP_LISTENER ||
        conn->type == CONN_TYPE_AP_TRANS_LISTENER ||
        conn->type == CONN_TYPE_AP_DNS_LISTENER ||
        conn->type == CONN_TYPE_AP_NATD_LISTENER ||
        conn->type == CONN_TYPE_AP_HTTP_CONNECT_LISTENER ||
        conn->type == CONN_TYPE_DIR_LISTENER ||
        conn->type == CONN_TYPE_CONTROL_LISTENER)
      return 1;
    return 0;
  }
  
  /** Return 1 if <b>conn</b> is in state "open" and is not marked
   * for close, else return 0.
   */
  int
  connection_state_is_open(connection_t *conn)
  {
    tor_assert(conn);
  
    if (conn->marked_for_close)
      return 0;
  
    if ((conn->type == CONN_TYPE_OR && conn->state == OR_CONN_STATE_OPEN) ||
        (conn->type == CONN_TYPE_EXT_OR) ||
        (conn->type == CONN_TYPE_AP && conn->state == AP_CONN_STATE_OPEN) ||
        (conn->type == CONN_TYPE_EXIT && conn->state == EXIT_CONN_STATE_OPEN) ||
        (conn->type == CONN_TYPE_CONTROL &&
         conn->state == CONTROL_CONN_STATE_OPEN))
      return 1;
  
    return 0;
  }
  
  /** Return 1 if conn is in 'connecting' state, else return 0. */
  int
  connection_state_is_connecting(connection_t *conn)
  {
    tor_assert(conn);
  
    if (conn->marked_for_close)
      return 0;
    switch (conn->type)
      {
      case CONN_TYPE_OR:
        return conn->state == OR_CONN_STATE_CONNECTING;
      case CONN_TYPE_EXIT:
        return conn->state == EXIT_CONN_STATE_CONNECTING;
      case CONN_TYPE_DIR:
        return conn->state == DIR_CONN_STATE_CONNECTING;
      }
  
    return 0;
  }
  
  /** Allocates a base64'ed authenticator for use in http or https
   * auth, based on the input string <b>authenticator</b>. Returns it
   * if success, else returns NULL. */
  char *
  alloc_http_authenticator(const char *authenticator)
  {
    /* an authenticator in Basic authentication
     * is just the string "username:password" */
    const size_t authenticator_length = strlen(authenticator);
    const size_t base64_authenticator_length =
        base64_encode_size(authenticator_length, 0) + 1;
    char *base64_authenticator = tor_malloc(base64_authenticator_length);
    if (base64_encode(base64_authenticator, base64_authenticator_length,
                      authenticator, authenticator_length, 0) < 0) {
      tor_free(base64_authenticator); /* free and set to null */
    }
    return base64_authenticator;
  }
  
  /** Given a socket handle, check whether the local address (sockname) of the
   * socket is one that we've connected from before.  If so, double-check
   * whether our address has changed and we need to generate keys.  If we do,
   * call init_keys().
   */
  static void
  client_check_address_changed(tor_socket_t sock)
  {
    tor_addr_t out_addr, iface_addr;
    tor_addr_t **last_interface_ip_ptr;
    sa_family_t family;
  
    if (!outgoing_addrs)
      outgoing_addrs = smartlist_new();
  
    if (tor_addr_from_getsockname(&out_addr, sock) < 0) {
      int e = tor_socket_errno(sock);
      log_warn(LD_NET, "getsockname() to check for address change failed: %s",
               tor_socket_strerror(e));
      return;
    }
    family = tor_addr_family(&out_addr);
  
    if (family == AF_INET)
      last_interface_ip_ptr = &last_interface_ipv4;
    else if (family == AF_INET6)
      last_interface_ip_ptr = &last_interface_ipv6;
    else
      return;
  
    if (! *last_interface_ip_ptr) {
      tor_addr_t *a = tor_malloc_zero(sizeof(tor_addr_t));
      if (get_interface_address6(LOG_INFO, family, a)==0) {
        *last_interface_ip_ptr = a;
      } else {
        tor_free(a);
      }
    }
  
    /* If we've used this address previously, we're okay. */
    SMARTLIST_FOREACH(outgoing_addrs, const tor_addr_t *, a_ptr,
                      if (tor_addr_eq(a_ptr, &out_addr))
                        return;
                      );
  
    /* Uh-oh.  We haven't connected from this address before. Has the interface
     * address changed? */
    if (get_interface_address6(LOG_INFO, family, &iface_addr)<0)
      return;
  
    if (tor_addr_eq(&iface_addr, *last_interface_ip_ptr)) {
      /* Nope, it hasn't changed.  Add this address to the list. */
      smartlist_add(outgoing_addrs, tor_memdup(&out_addr, sizeof(tor_addr_t)));
    } else {
      /* The interface changed.  We're a client, so we need to regenerate our
       * keys.  First, reset the state. */
      log_notice(LD_NET, "Our IP address has changed.  Rotating keys...");
      tor_addr_copy(*last_interface_ip_ptr, &iface_addr);
      SMARTLIST_FOREACH(outgoing_addrs, tor_addr_t*, a_ptr, tor_free(a_ptr));
      smartlist_clear(outgoing_addrs);
      smartlist_add(outgoing_addrs, tor_memdup(&out_addr, sizeof(tor_addr_t)));
      /* We'll need to resolve ourselves again. */
      reset_last_resolved_addr();
      /* Okay, now change our keys. */
      ip_address_changed(1);
    }
  }
  
  /** Some systems have limited system buffers for recv and xmit on
   * sockets allocated in a virtual server or similar environment. For a Tor
   * server this can produce the "Error creating network socket: No buffer
   * space available" error once all available TCP buffer space is consumed.
   * This method will attempt to constrain the buffers allocated for the socket
   * to the desired size to stay below system TCP buffer limits.
   */
  static void
  set_constrained_socket_buffers(tor_socket_t sock, int size)
  {
    void *sz = (void*)&size;
    socklen_t sz_sz = (socklen_t) sizeof(size);
    if (setsockopt(sock, SOL_SOCKET, SO_SNDBUF, sz, sz_sz) < 0) {
      int e = tor_socket_errno(sock);
      log_warn(LD_NET, "setsockopt() to constrain send "
               "buffer to %d bytes failed: %s", size, tor_socket_strerror(e));
    }
    if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, sz, sz_sz) < 0) {
      int e = tor_socket_errno(sock);
      log_warn(LD_NET, "setsockopt() to constrain recv "
               "buffer to %d bytes failed: %s", size, tor_socket_strerror(e));
    }
  }
  
  /** Process new bytes that have arrived on conn-\>inbuf.
   *
   * This function just passes conn to the connection-specific
   * connection_*_process_inbuf() function. It also passes in
   * package_partial if wanted.
   */
  static int
  connection_process_inbuf(connection_t *conn, int package_partial)
  {
    tor_assert(conn);
  
    switch (conn->type) {
      case CONN_TYPE_OR:
        return connection_or_process_inbuf(TO_OR_CONN(conn));
      case CONN_TYPE_EXT_OR:
        return connection_ext_or_process_inbuf(TO_OR_CONN(conn));
      case CONN_TYPE_EXIT:
      case CONN_TYPE_AP:
        return connection_edge_process_inbuf(TO_EDGE_CONN(conn),
                                             package_partial);
      case CONN_TYPE_DIR:
        return connection_dir_process_inbuf(TO_DIR_CONN(conn));
      case CONN_TYPE_CONTROL:
        return connection_control_process_inbuf(TO_CONTROL_CONN(conn));
      default:
        log_err(LD_BUG,"got unexpected conn type %d.", conn->type);
        tor_fragile_assert();
        return -1;
    }
  }
  
  /** Called whenever we've written data on a connection. */
  static int
  connection_flushed_some(connection_t *conn)
  {
    int r = 0;
    tor_assert(!conn->in_flushed_some);
    conn->in_flushed_some = 1;
    if (conn->type == CONN_TYPE_DIR &&
        conn->state == DIR_CONN_STATE_SERVER_WRITING) {
      r = connection_dirserv_flushed_some(TO_DIR_CONN(conn));
    } else if (conn->type == CONN_TYPE_OR) {
      r = connection_or_flushed_some(TO_OR_CONN(conn));
    } else if (CONN_IS_EDGE(conn)) {
      r = connection_edge_flushed_some(TO_EDGE_CONN(conn));
    }
    conn->in_flushed_some = 0;
    return r;
  }
  
  /** We just finished flushing bytes to the appropriately low network layer,
   * and there are no more bytes remaining in conn-\>outbuf or
   * conn-\>tls to be flushed.
   *
   * This function just passes conn to the connection-specific
   * connection_*_finished_flushing() function.
   */
  static int
  connection_finished_flushing(connection_t *conn)
  {
    tor_assert(conn);
  
    /* If the connection is closed, don't try to do anything more here. */
    if (CONN_IS_CLOSED(conn))
      return 0;
  
  //  log_fn(LOG_DEBUG,"entered. Socket %u.", conn->s);
  
    connection_stop_writing(conn);
  
    switch (conn->type) {
      case CONN_TYPE_OR:
        return connection_or_finished_flushing(TO_OR_CONN(conn));
      case CONN_TYPE_EXT_OR:
        return connection_ext_or_finished_flushing(TO_OR_CONN(conn));
      case CONN_TYPE_AP:
      case CONN_TYPE_EXIT:
        return connection_edge_finished_flushing(TO_EDGE_CONN(conn));
      case CONN_TYPE_DIR:
        return connection_dir_finished_flushing(TO_DIR_CONN(conn));
      case CONN_TYPE_CONTROL:
        return connection_control_finished_flushing(TO_CONTROL_CONN(conn));
      default:
        log_err(LD_BUG,"got unexpected conn type %d.", conn->type);
        tor_fragile_assert();
        return -1;
    }
  }
  
  /** Called when our attempt to connect() to another server has just
   * succeeded.
   *
   * This function just passes conn to the connection-specific
   * connection_*_finished_connecting() function.
   */
  static int
  connection_finished_connecting(connection_t *conn)
  {
    tor_assert(conn);
  
    if (!server_mode(get_options())) {
      /* See whether getsockname() says our address changed.  We need to do this
       * now that the connection has finished, because getsockname() on Windows
       * won't work until then. */
      client_check_address_changed(conn->s);
    }
  
    switch (conn->type)
      {
      case CONN_TYPE_OR:
        return connection_or_finished_connecting(TO_OR_CONN(conn));
      case CONN_TYPE_EXIT:
        return connection_edge_finished_connecting(TO_EDGE_CONN(conn));
      case CONN_TYPE_DIR:
        return connection_dir_finished_connecting(TO_DIR_CONN(conn));
      default:
        log_err(LD_BUG,"got unexpected conn type %d.", conn->type);
        tor_fragile_assert();
        return -1;
    }
  }
  
  /** Callback: invoked when a connection reaches an EOF event. */
  static int
  connection_reached_eof(connection_t *conn)
  {
    switch (conn->type) {
      case CONN_TYPE_OR:
      case CONN_TYPE_EXT_OR:
        return connection_or_reached_eof(TO_OR_CONN(conn));
      case CONN_TYPE_AP:
      case CONN_TYPE_EXIT:
        return connection_edge_reached_eof(TO_EDGE_CONN(conn));
      case CONN_TYPE_DIR:
        return connection_dir_reached_eof(TO_DIR_CONN(conn));
      case CONN_TYPE_CONTROL:
        return connection_control_reached_eof(TO_CONTROL_CONN(conn));
      default:
        log_err(LD_BUG,"got unexpected conn type %d.", conn->type);
        tor_fragile_assert();
        return -1;
    }
  }
  
  /** Comparator for the two-orconn case in OOS victim sort */
  static int
  oos_victim_comparator_for_orconns(or_connection_t *a, or_connection_t *b)
  {
    int a_circs, b_circs;
    /* Fewer circuits == higher priority for OOS kill, sort earlier */
  
    a_circs = connection_or_get_num_circuits(a);
    b_circs = connection_or_get_num_circuits(b);
  
    if (a_circs < b_circs) return 1;
    else if (a_circs > b_circs) return -1;
    else return 0;
  }
  
  /** Sort comparator for OOS victims; better targets sort before worse
   * ones. */
  static int
  oos_victim_comparator(const void **a_v, const void **b_v)
  {
    connection_t *a = NULL, *b = NULL;
  
    /* Get connection pointers out */
  
    a = (connection_t *)(*a_v);
    b = (connection_t *)(*b_v);
  
    tor_assert(a != NULL);
    tor_assert(b != NULL);
  
    /*
     * We always prefer orconns as victims currently; we won't even see
     * these non-orconn cases, but if we do, sort them after orconns.
     */
    if (a->type == CONN_TYPE_OR && b->type == CONN_TYPE_OR) {
      return oos_victim_comparator_for_orconns(TO_OR_CONN(a), TO_OR_CONN(b));
    } else {
      /*
       * One isn't an orconn; if one is, it goes first.  We currently have no
       * opinions about cases where neither is an orconn.
       */
      if (a->type == CONN_TYPE_OR) return -1;
      else if (b->type == CONN_TYPE_OR) return 1;
      else return 0;
    }
  }
  
  /** Pick n victim connections for the OOS handler and return them in a
   * smartlist.
   */
  MOCK_IMPL(STATIC smartlist_t *,
  pick_oos_victims, (int n))
  {
    smartlist_t *eligible = NULL, *victims = NULL;
    smartlist_t *conns;
    int conn_counts_by_type[CONN_TYPE_MAX_ + 1], i;
  
    /*
     * Big damn assumption (someone improve this someday!):
     *
     * Socket exhaustion normally happens on high-volume relays, and so
     * most of the connections involved are orconns.  We should pick victims
     * by assembling a list of all orconns, and sorting them in order of
     * how much 'damage' by some metric we'd be doing by dropping them.
     *
     * If we move on from orconns, we should probably think about incoming
     * directory connections next, or exit connections.  Things we should
     * probably never kill are controller connections and listeners.
     *
     * This function will count how many connections of different types
     * exist and log it for purposes of gathering data on typical OOS
     * situations to guide future improvements.
     */
  
    /* First, get the connection array */
    conns = get_connection_array();
    /*
     * Iterate it and pick out eligible connection types, and log some stats
     * along the way.
     */
    eligible = smartlist_new();
    memset(conn_counts_by_type, 0, sizeof(conn_counts_by_type));
    SMARTLIST_FOREACH_BEGIN(conns, connection_t *, c) {
      /* Bump the counter */
      tor_assert(c->type <= CONN_TYPE_MAX_);
      ++(conn_counts_by_type[c->type]);
  
      /* Skip anything without a socket we can free */
      if (!(SOCKET_OK(c->s))) {
        continue;
      }
  
      /* Skip anything we would count as moribund */
      if (connection_is_moribund(c)) {
        continue;
      }
  
      switch (c->type) {
        case CONN_TYPE_OR:
          /* We've got an orconn, it's eligible to be OOSed */
          smartlist_add(eligible, c);
          break;
        default:
          /* We don't know what to do with it, ignore it */
          break;
      }
    } SMARTLIST_FOREACH_END(c);
  
    /* Log some stats */
    if (smartlist_len(conns) > 0) {
      /* At least one counter must be non-zero */
      log_info(LD_NET, "Some stats on conn types seen during OOS follow");
      for (i = CONN_TYPE_MIN_; i <= CONN_TYPE_MAX_; ++i) {
        /* Did we see any? */
        if (conn_counts_by_type[i] > 0) {
          log_info(LD_NET, "%s: %d conns",
                   conn_type_to_string(i),
                   conn_counts_by_type[i]);
        }
      }
      log_info(LD_NET, "Done with OOS conn type stats");
    }
  
    /* Did we find more eligible targets than we want to kill? */
    if (smartlist_len(eligible) > n) {
      /* Sort the list in order of target preference */
      smartlist_sort(eligible, oos_victim_comparator);
      /* Pick first n as victims */
      victims = smartlist_new();
      for (i = 0; i < n; ++i) {
        smartlist_add(victims, smartlist_get(eligible, i));
      }
      /* Free the original list */
      smartlist_free(eligible);
    } else {
      /* No, we can just call them all victims */
      victims = eligible;
    }
  
    return victims;
  }
  
  /** Kill a list of connections for the OOS handler. */
  MOCK_IMPL(STATIC void,
  kill_conn_list_for_oos, (smartlist_t *conns))
  {
    if (!conns) return;
  
    SMARTLIST_FOREACH_BEGIN(conns, connection_t *, c) {
      /* Make sure the channel layer gets told about orconns */
      if (c->type == CONN_TYPE_OR) {
        connection_or_close_for_error(TO_OR_CONN(c), 1);
      } else {
        connection_mark_for_close(c);
      }
    } SMARTLIST_FOREACH_END(c);
  
    log_notice(LD_NET,
               "OOS handler marked %d connections",
               smartlist_len(conns));
  }
  
  /** Check if a connection is on the way out so the OOS handler doesn't try
   * to kill more than it needs. */
  int
  connection_is_moribund(connection_t *conn)
  {
    if (conn != NULL &&
        (conn->conn_array_index < 0 ||
         conn->marked_for_close)) {
      return 1;
    } else {
      return 0;
    }
  }
  
  /** Out-of-Sockets handler; n_socks is the current number of open
   * sockets, and failed is non-zero if a socket exhaustion related
   * error immediately preceded this call.  This is where to do
   * circuit-killing heuristics as needed.
   */
  void
  connection_check_oos(int n_socks, int failed)
  {
    int target_n_socks = 0, moribund_socks, socks_to_kill;
    smartlist_t *conns;
  
    /* Early exit: is OOS checking disabled? */
    if (get_options()->DisableOOSCheck) {
      return;
    }
  
    /* Sanity-check args */
    tor_assert(n_socks >= 0);
  
    /*
     * Make some log noise; keep it at debug level since this gets a chance
     * to run on every connection attempt.
     */
    log_debug(LD_NET,
              "Running the OOS handler (%d open sockets, %s)",
              n_socks, (failed != 0) ? "exhaustion seen" : "no exhaustion");
  
    /*
     * Check if we're really handling an OOS condition, and if so decide how
     * many sockets we want to get down to.  Be sure we check if the threshold
     * is distinct from zero first; it's possible for this to be called a few
     * times before we've finished reading the config.
     */
    if (n_socks >= get_options()->ConnLimit_high_thresh &&
        get_options()->ConnLimit_high_thresh != 0 &&
        get_options()->ConnLimit_ != 0) {
      /* Try to get down to the low threshold */
      target_n_socks = get_options()->ConnLimit_low_thresh;
      log_notice(LD_NET,
                 "Current number of sockets %d is greater than configured "
                 "limit %d; OOS handler trying to get down to %d",
                 n_socks, get_options()->ConnLimit_high_thresh,
                 target_n_socks);
    } else if (failed) {
      /*
       * If we're not at the limit but we hit a socket exhaustion error, try to
       * drop some (but not as aggressively as ConnLimit_low_threshold, which is
       * 3/4 of ConnLimit_)
       */
      target_n_socks = (n_socks * 9) / 10;
      log_notice(LD_NET,
                 "We saw socket exhaustion at %d open sockets; OOS handler "
                 "trying to get down to %d",
                 n_socks, target_n_socks);
    }
  
    if (target_n_socks > 0) {
      /*
       * It's an OOS!
       *
       * Count moribund sockets; it's be important that anything we decide
       * to get rid of here but don't immediately close get counted as moribund
       * on subsequent invocations so we don't try to kill too many things if
       * connection_check_oos() gets called multiple times.
       */
      moribund_socks = connection_count_moribund();
  
      if (moribund_socks < n_socks - target_n_socks) {
        socks_to_kill = n_socks - target_n_socks - moribund_socks;
  
        conns = pick_oos_victims(socks_to_kill);
        if (conns) {
          kill_conn_list_for_oos(conns);
          log_notice(LD_NET,
                     "OOS handler killed %d conns", smartlist_len(conns));
          smartlist_free(conns);
        } else {
          log_notice(LD_NET, "OOS handler failed to pick any victim conns");
        }
      } else {
        log_notice(LD_NET,
                   "Not killing any sockets for OOS because there are %d "
                   "already moribund, and we only want to eliminate %d",
                   moribund_socks, n_socks - target_n_socks);
      }
    }
  }
  
  /** Log how many bytes are used by buffers of different kinds and sizes. */
  void
  connection_dump_buffer_mem_stats(int severity)
  {
    uint64_t used_by_type[CONN_TYPE_MAX_+1];
    uint64_t alloc_by_type[CONN_TYPE_MAX_+1];
    int n_conns_by_type[CONN_TYPE_MAX_+1];
    uint64_t total_alloc = 0;
    uint64_t total_used = 0;
    int i;
    smartlist_t *conns = get_connection_array();
  
    memset(used_by_type, 0, sizeof(used_by_type));
    memset(alloc_by_type, 0, sizeof(alloc_by_type));
    memset(n_conns_by_type, 0, sizeof(n_conns_by_type));
  
    SMARTLIST_FOREACH_BEGIN(conns, connection_t *, c) {
      int tp = c->type;
      ++n_conns_by_type[tp];
      if (c->inbuf) {
        used_by_type[tp] += buf_datalen(c->inbuf);
        alloc_by_type[tp] += buf_allocation(c->inbuf);
      }
      if (c->outbuf) {
        used_by_type[tp] += buf_datalen(c->outbuf);
        alloc_by_type[tp] += buf_allocation(c->outbuf);
      }
    } SMARTLIST_FOREACH_END(c);
    for (i=0; i <= CONN_TYPE_MAX_; ++i) {
      total_used += used_by_type[i];
      total_alloc += alloc_by_type[i];
    }
  
    tor_log(severity, LD_GENERAL,
       "In buffers for %d connections: %"PRIu64" used/%"PRIu64" allocated",
        smartlist_len(conns),
        (total_used), (total_alloc));
    for (i=CONN_TYPE_MIN_; i <= CONN_TYPE_MAX_; ++i) {
      if (!n_conns_by_type[i])
        continue;
      tor_log(severity, LD_GENERAL,
          "  For %d %s connections: %"PRIu64" used/%"PRIu64" allocated",
          n_conns_by_type[i], conn_type_to_string(i),
          (used_by_type[i]), (alloc_by_type[i]));
    }
  }
  
  /** Verify that connection <b>conn</b> has all of its invariants
   * correct. Trigger an assert if anything is invalid.
   */
  void
  assert_connection_ok(connection_t *conn, time_t now)
  {
    (void) now; /* XXXX unused. */
    tor_assert(conn);
    tor_assert(conn->type >= CONN_TYPE_MIN_);
    tor_assert(conn->type <= CONN_TYPE_MAX_);
  
    switch (conn->type) {
      case CONN_TYPE_OR:
      case CONN_TYPE_EXT_OR:
        tor_assert(conn->magic == OR_CONNECTION_MAGIC);
        break;
      case CONN_TYPE_AP:
        tor_assert(conn->magic == ENTRY_CONNECTION_MAGIC);
        break;
      case CONN_TYPE_EXIT:
        tor_assert(conn->magic == EDGE_CONNECTION_MAGIC);
        break;
      case CONN_TYPE_DIR:
        tor_assert(conn->magic == DIR_CONNECTION_MAGIC);
        break;
      case CONN_TYPE_CONTROL:
        tor_assert(conn->magic == CONTROL_CONNECTION_MAGIC);
        break;
      CASE_ANY_LISTENER_TYPE:
        tor_assert(conn->magic == LISTENER_CONNECTION_MAGIC);
        break;
      default:
        tor_assert(conn->magic == BASE_CONNECTION_MAGIC);
        break;
    }
  
    if (conn->linked_conn) {
      tor_assert(conn->linked_conn->linked_conn == conn);
      tor_assert(conn->linked);
    }
    if (conn->linked)
      tor_assert(!SOCKET_OK(conn->s));
  
    if (conn->outbuf_flushlen > 0) {
      /* With optimistic data, we may have queued data in
       * EXIT_CONN_STATE_RESOLVING while the conn is not yet marked to writing.
       * */
      tor_assert((conn->type == CONN_TYPE_EXIT &&
                  conn->state == EXIT_CONN_STATE_RESOLVING) ||
                 connection_is_writing(conn) ||
                 conn->write_blocked_on_bw ||
                 (CONN_IS_EDGE(conn) &&
                  TO_EDGE_CONN(conn)->edge_blocked_on_circ));
    }
  
    if (conn->hold_open_until_flushed)
      tor_assert(conn->marked_for_close);
  
    /* XXXX check: read_blocked_on_bw, write_blocked_on_bw, s, conn_array_index,
     * marked_for_close. */
  
    /* buffers */
    if (conn->inbuf)
      buf_assert_ok(conn->inbuf);
    if (conn->outbuf)
      buf_assert_ok(conn->outbuf);
  
    if (conn->type == CONN_TYPE_OR) {
      or_connection_t *or_conn = TO_OR_CONN(conn);
      if (conn->state == OR_CONN_STATE_OPEN) {
        /* tor_assert(conn->bandwidth > 0); */
        /* the above isn't necessarily true: if we just did a TLS
         * handshake but we didn't recognize the other peer, or it
         * gave a bad cert/etc, then we won't have assigned bandwidth,
         * yet it will be open. -RD
         */
  //      tor_assert(conn->read_bucket >= 0);
      }
  //    tor_assert(conn->addr && conn->port);
      tor_assert(conn->address);
      if (conn->state > OR_CONN_STATE_PROXY_HANDSHAKING)
        tor_assert(or_conn->tls);
    }
  
    if (CONN_IS_EDGE(conn)) {
      /* XXX unchecked: package window, deliver window. */
      if (conn->type == CONN_TYPE_AP) {
        entry_connection_t *entry_conn = TO_ENTRY_CONN(conn);
        if (entry_conn->chosen_exit_optional || entry_conn->chosen_exit_retries)
          tor_assert(entry_conn->chosen_exit_name);
  
        tor_assert(entry_conn->socks_request);
        if (conn->state == AP_CONN_STATE_OPEN) {
          tor_assert(entry_conn->socks_request->has_finished);
          if (!conn->marked_for_close) {
            tor_assert(ENTRY_TO_EDGE_CONN(entry_conn)->cpath_layer);
            assert_cpath_layer_ok(ENTRY_TO_EDGE_CONN(entry_conn)->cpath_layer);
          }
        }
      }
      if (conn->type == CONN_TYPE_EXIT) {
        tor_assert(conn->purpose == EXIT_PURPOSE_CONNECT ||
                   conn->purpose == EXIT_PURPOSE_RESOLVE);
      }
    } else if (conn->type == CONN_TYPE_DIR) {
    } else {
      /* Purpose is only used for dir and exit types currently */
      tor_assert(!conn->purpose);
    }
  
    switch (conn->type)
      {
      CASE_ANY_LISTENER_TYPE:
        tor_assert(conn->state == LISTENER_STATE_READY);
        break;
      case CONN_TYPE_OR:
        tor_assert(conn->state >= OR_CONN_STATE_MIN_);
        tor_assert(conn->state <= OR_CONN_STATE_MAX_);
        break;
      case CONN_TYPE_EXT_OR:
        tor_assert(conn->state >= EXT_OR_CONN_STATE_MIN_);
        tor_assert(conn->state <= EXT_OR_CONN_STATE_MAX_);
        break;
      case CONN_TYPE_EXIT:
        tor_assert(conn->state >= EXIT_CONN_STATE_MIN_);
        tor_assert(conn->state <= EXIT_CONN_STATE_MAX_);
        tor_assert(conn->purpose >= EXIT_PURPOSE_MIN_);
        tor_assert(conn->purpose <= EXIT_PURPOSE_MAX_);
        break;
      case CONN_TYPE_AP:
        tor_assert(conn->state >= AP_CONN_STATE_MIN_);
        tor_assert(conn->state <= AP_CONN_STATE_MAX_);
        tor_assert(TO_ENTRY_CONN(conn)->socks_request);
        break;
      case CONN_TYPE_DIR:
        tor_assert(conn->state >= DIR_CONN_STATE_MIN_);
        tor_assert(conn->state <= DIR_CONN_STATE_MAX_);
        tor_assert(conn->purpose >= DIR_PURPOSE_MIN_);
        tor_assert(conn->purpose <= DIR_PURPOSE_MAX_);
        break;
      case CONN_TYPE_CONTROL:
        tor_assert(conn->state >= CONTROL_CONN_STATE_MIN_);
        tor_assert(conn->state <= CONTROL_CONN_STATE_MAX_);
        break;
      default:
        tor_assert(0);
    }
  }
  
  /** Fills <b>addr</b> and <b>port</b> with the details of the global
   *  proxy server we are using.
   *  <b>conn</b> contains the connection we are using the proxy for.
   *
   *  Return 0 on success, -1 on failure.
   */
  int
  get_proxy_addrport(tor_addr_t *addr, uint16_t *port, int *proxy_type,
                     const connection_t *conn)
  {
    const or_options_t *options = get_options();
  
    /* Client Transport Plugins can use another proxy, but that should be hidden
     * from the rest of tor (as the plugin is responsible for dealing with the
     * proxy), check it first, then check the rest of the proxy types to allow
     * the config to have unused ClientTransportPlugin entries.
     */
    if (options->ClientTransportPlugin) {
      const transport_t *transport = NULL;
      int r;
      r = get_transport_by_bridge_addrport(&conn->addr, conn->port, &transport);
      if (r<0)
        return -1;
      if (transport) { /* transport found */
        tor_addr_copy(addr, &transport->addr);
        *port = transport->port;
        *proxy_type = transport->socks_version;
        return 0;
      }
  
      /* Unused ClientTransportPlugin. */
    }
  
    if (options->HTTPSProxy) {
      tor_addr_copy(addr, &options->HTTPSProxyAddr);
      *port = options->HTTPSProxyPort;
      *proxy_type = PROXY_CONNECT;
      return 0;
    } else if (options->Socks4Proxy) {
      tor_addr_copy(addr, &options->Socks4ProxyAddr);
      *port = options->Socks4ProxyPort;
      *proxy_type = PROXY_SOCKS4;
      return 0;
    } else if (options->Socks5Proxy) {
      tor_addr_copy(addr, &options->Socks5ProxyAddr);
      *port = options->Socks5ProxyPort;
      *proxy_type = PROXY_SOCKS5;
      return 0;
    }
  
    tor_addr_make_unspec(addr);
    *port = 0;
    *proxy_type = PROXY_NONE;
    return 0;
  }
  
  /** Log a failed connection to a proxy server.
   *  <b>conn</b> is the connection we use the proxy server for. */
  void
  log_failed_proxy_connection(connection_t *conn)
  {
    tor_addr_t proxy_addr;
    uint16_t proxy_port;
    int proxy_type;
  
    if (get_proxy_addrport(&proxy_addr, &proxy_port, &proxy_type, conn) != 0)
      return; /* if we have no proxy set up, leave this function. */
  
    log_warn(LD_NET,
             "The connection to the %s proxy server at %s just failed. "
             "Make sure that the proxy server is up and running.",
             proxy_type_to_string(proxy_type),
             fmt_addrport(&proxy_addr, proxy_port));
  }
  
  /** Return string representation of <b>proxy_type</b>. */
  static const char *
  proxy_type_to_string(int proxy_type)
  {
    switch (proxy_type) {
    case PROXY_CONNECT:   return "HTTP";
    case PROXY_SOCKS4:    return "SOCKS4";
    case PROXY_SOCKS5:    return "SOCKS5";
    case PROXY_PLUGGABLE: return "pluggable transports SOCKS";
    case PROXY_NONE:      return "NULL";
    default:              tor_assert(0);
    }
    return NULL; /*Unreached*/
  }
  
  /** Call connection_free_minimal() on every connection in our array, and
   * release all storage held by connection.c.
   *
   * Don't do the checks in connection_free(), because they will
   * fail.
   */
  void
  connection_free_all(void)
  {
    smartlist_t *conns = get_connection_array();
  
    /* We don't want to log any messages to controllers. */
    SMARTLIST_FOREACH(conns, connection_t *, conn,
      if (conn->type == CONN_TYPE_CONTROL)
        TO_CONTROL_CONN(conn)->event_mask = 0);
  
    control_update_global_event_mask();
  
    /* Unlink everything from the identity map. */
    connection_or_clear_identity_map();
    connection_or_clear_ext_or_id_map();
  
    /* Clear out our list of broken connections */
    clear_broken_connection_map(0);
  
    SMARTLIST_FOREACH(conns, connection_t *, conn,
                      connection_free_minimal(conn));
  
    if (outgoing_addrs) {
      SMARTLIST_FOREACH(outgoing_addrs, tor_addr_t *, addr, tor_free(addr));
      smartlist_free(outgoing_addrs);
      outgoing_addrs = NULL;
    }
  
    tor_free(last_interface_ipv4);
    tor_free(last_interface_ipv6);
    last_recorded_accounting_at = 0;
  
    mainloop_event_free(reenable_blocked_connections_ev);
    reenable_blocked_connections_is_scheduled = 0;
    memset(&reenable_blocked_connections_delay, 0, sizeof(struct timeval));
  }
  
  /** Log a warning, and possibly emit a control event, that <b>received</b> came
   * at a skewed time.  <b>trusted</b> indicates that the <b>source</b> was one
   * that we had more faith in and therefore the warning level should have higher
   * severity.
   */
  MOCK_IMPL(void,
  clock_skew_warning, (const connection_t *conn, long apparent_skew, int trusted,
                       log_domain_mask_t domain, const char *received,
                       const char *source))
  {
    char dbuf[64];
    char *ext_source = NULL, *warn = NULL;
    format_time_interval(dbuf, sizeof(dbuf), apparent_skew);
    if (conn)
      tor_asprintf(&ext_source, "%s:%s:%d", source, conn->address, conn->port);
    else
      ext_source = tor_strdup(source);
    log_fn(trusted ? LOG_WARN : LOG_INFO, domain,
           "Received %s with skewed time (%s): "
           "It seems that our clock is %s by %s, or that theirs is %s%s. "
           "Tor requires an accurate clock to work: please check your time, "
           "timezone, and date settings.", received, ext_source,
           apparent_skew > 0 ? "ahead" : "behind", dbuf,
           apparent_skew > 0 ? "behind" : "ahead",
           (!conn || trusted) ? "" : ", or they are sending us the wrong time");
    if (trusted) {
      control_event_general_status(LOG_WARN, "CLOCK_SKEW SKEW=%ld SOURCE=%s",
                                   apparent_skew, ext_source);
      tor_asprintf(&warn, "Clock skew %ld in %s from %s", apparent_skew,
                   received, source);
      control_event_bootstrap_problem(warn, "CLOCK_SKEW", conn, 1);
    }
    tor_free(warn);
    tor_free(ext_source);
  }
  