text: /* Copyright (c) 2001 Matej Pfajfar.
   * Copyright (c) 2001-2004, Roger Dingledine.
   * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   * Copyright (c) 2007-2020, The Tor Project, Inc. */
  /* See LICENSE for licensing information */
  
  /**
   * \file or.h
   * \brief Master header file for Tor-specific functionality.
   **/
  
  #ifndef TOR_OR_H
  #define TOR_OR_H
  
  #include "orconfig.h"
  #include "lib/cc/torint.h"
  
  #ifdef HAVE_SIGNAL_H
  #include <signal.h>
  #endif
  #ifdef HAVE_TIME_H
  #include <time.h>
  #endif
  
  #include "lib/arch/bytes.h"
  #include "lib/cc/compat_compiler.h"
  #include "lib/container/map.h"
  #include "lib/buf/buffers.h"
  #include "lib/container/smartlist.h"
  #include "lib/crypt_ops/crypto_cipher.h"
  #include "lib/crypt_ops/crypto_rsa.h"
  #include "lib/ctime/di_ops.h"
  #include "lib/defs/dh_sizes.h"
  #include "lib/encoding/binascii.h"
  #include "lib/encoding/cstring.h"
  #include "lib/encoding/time_fmt.h"
  #include "lib/err/torerr.h"
  #include "lib/fs/dir.h"
  #include "lib/fs/files.h"
  #include "lib/fs/mmap.h"
  #include "lib/fs/path.h"
  #include "lib/fs/userdb.h"
  #include "lib/geoip/country.h"
  #include "lib/intmath/addsub.h"
  #include "lib/intmath/bits.h"
  #include "lib/intmath/cmp.h"
  #include "lib/intmath/logic.h"
  #include "lib/intmath/muldiv.h"
  #include "lib/log/escape.h"
  #include "lib/log/ratelim.h"
  #include "lib/log/util_bug.h"
  #include "lib/malloc/malloc.h"
  #include "lib/net/address.h"
  #include "lib/net/inaddr.h"
  #include "lib/net/socket.h"
  #include "lib/string/compat_ctype.h"
  #include "lib/string/compat_string.h"
  #include "lib/string/parse_int.h"
  #include "lib/string/printf.h"
  #include "lib/string/scanf.h"
  #include "lib/string/util_string.h"
  #include "lib/testsupport/testsupport.h"
  #include "lib/thread/threads.h"
  #include "lib/time/compat_time.h"
  #include "lib/wallclock/approx_time.h"
  #include "lib/wallclock/timeval.h"
  
  #include "ht.h"
  
  // These, more than other includes, are for keeping the other struct
  // definitions working. We should remove them when we minimize our includes.
  #include "core/or/entry_port_cfg_st.h"
  
  struct ed25519_public_key_t;
  struct curve25519_public_key_t;
  
  /* These signals are defined to help handle_control_signal work.
   */
  #ifndef SIGHUP
  #define SIGHUP 1
  #endif
  #ifndef SIGINT
  #define SIGINT 2
  #endif
  #ifndef SIGUSR1
  #define SIGUSR1 10
  #endif
  #ifndef SIGUSR2
  #define SIGUSR2 12
  #endif
  #ifndef SIGTERM
  #define SIGTERM 15
  #endif
  /* Controller signals start at a high number so we don't
   * conflict with system-defined signals. */
  #define SIGNEWNYM 129
  #define SIGCLEARDNSCACHE 130
  #define SIGHEARTBEAT 131
  #define SIGACTIVE 132
  #define SIGDORMANT 133
  
  #if (SIZEOF_CELL_T != 0)
  /* On Irix, stdlib.h defines a cell_t type, so we need to make sure
   * that our stuff always calls cell_t something different. */
  #define cell_t tor_cell_t
  #endif
  
  /** Helper macro: Given a pointer to to.base_, of type from*, return &to. */
  #define DOWNCAST(to, ptr) ((to*)SUBTYPE_P(ptr, to, base_))
  
  /** Length of longest allowable configured nickname. */
  #define MAX_NICKNAME_LEN 19
  /** Length of a router identity encoded as a hexadecimal digest, plus
   * possible dollar sign. */
  #define MAX_HEX_NICKNAME_LEN (HEX_DIGEST_LEN+1)
  /** Maximum length of verbose router identifier: dollar sign, hex ID digest,
   * equal sign or tilde, nickname. */
  #define MAX_VERBOSE_NICKNAME_LEN (1+HEX_DIGEST_LEN+1+MAX_NICKNAME_LEN)
  
  /** For HTTP parsing: Maximum number of bytes we'll accept in the headers
   * of an HTTP request or response. */
  #define MAX_HEADERS_SIZE 50000
  
  /** Maximum size, in bytes, of a single router descriptor uploaded to us
   * as a directory authority. Caches and clients fetch whatever descriptors
   * the authorities tell them to fetch, and don't care about size. */
  #define MAX_DESCRIPTOR_UPLOAD_SIZE 20000
  
  /** Maximum size of a single extrainfo document, as above. */
  #define MAX_EXTRAINFO_UPLOAD_SIZE 50000
  
  /** Minimum lifetime for an onion key in days. */
  #define MIN_ONION_KEY_LIFETIME_DAYS (1)
  
  /** Maximum lifetime for an onion key in days. */
  #define MAX_ONION_KEY_LIFETIME_DAYS (90)
  
  /** Default lifetime for an onion key in days. */
  #define DEFAULT_ONION_KEY_LIFETIME_DAYS (28)
  
  /** Minimum grace period for acceptance of an onion key in days.
   * The maximum value is defined in proposal #274 as being the current network
   * consensus parameter for "onion-key-rotation-days". */
  #define MIN_ONION_KEY_GRACE_PERIOD_DAYS (1)
  
  /** Default grace period for acceptance of an onion key in days. */
  #define DEFAULT_ONION_KEY_GRACE_PERIOD_DAYS (7)
  
  /** How often we should check the network consensus if it is time to rotate or
   * expire onion keys. */
  #define ONION_KEY_CONSENSUS_CHECK_INTERVAL (60*60)
  
  /** How often do we rotate TLS contexts? */
  #define MAX_SSL_KEY_LIFETIME_INTERNAL (2*60*60)
  
  /** How old do we allow a router to get before removing it
   * from the router list? In seconds. */
  #define ROUTER_MAX_AGE (60*60*48)
  /** How old can a router get before we (as a server) will no longer
   * consider it live? In seconds. */
  #define ROUTER_MAX_AGE_TO_PUBLISH (60*60*24)
  /** How old do we let a saved descriptor get before force-removing it? */
  #define OLD_ROUTER_DESC_MAX_AGE (60*60*24*5)
  
  /* Proxy client types */
  #define PROXY_NONE 0
  #define PROXY_CONNECT 1
  #define PROXY_SOCKS4 2
  #define PROXY_SOCKS5 3
  #define PROXY_HAPROXY 4
  /* !!!! If there is ever a PROXY_* type over 7, we must grow the proxy_type
   * field in or_connection_t */
  
  /* Pluggable transport proxy type. Don't use this in or_connection_t,
   * instead use the actual underlying proxy type (see above).  */
  #define PROXY_PLUGGABLE 5
  
  /** How many circuits do we want simultaneously in-progress to handle
   * a given stream? */
  #define MIN_CIRCUITS_HANDLING_STREAM 2
  
  /* These RELAY_COMMAND constants define values for relay cell commands, and
  * must match those defined in tor-spec.txt. */
  #define RELAY_COMMAND_BEGIN 1
  #define RELAY_COMMAND_DATA 2
  #define RELAY_COMMAND_END 3
  #define RELAY_COMMAND_CONNECTED 4
  #define RELAY_COMMAND_SENDME 5
  #define RELAY_COMMAND_EXTEND 6
  #define RELAY_COMMAND_EXTENDED 7
  #define RELAY_COMMAND_TRUNCATE 8
  #define RELAY_COMMAND_TRUNCATED 9
  #define RELAY_COMMAND_DROP 10
  #define RELAY_COMMAND_RESOLVE 11
  #define RELAY_COMMAND_RESOLVED 12
  #define RELAY_COMMAND_BEGIN_DIR 13
  #define RELAY_COMMAND_EXTEND2 14
  #define RELAY_COMMAND_EXTENDED2 15
  
  #define RELAY_COMMAND_ESTABLISH_INTRO 32
  #define RELAY_COMMAND_ESTABLISH_RENDEZVOUS 33
  #define RELAY_COMMAND_INTRODUCE1 34
  #define RELAY_COMMAND_INTRODUCE2 35
  #define RELAY_COMMAND_RENDEZVOUS1 36
  #define RELAY_COMMAND_RENDEZVOUS2 37
  #define RELAY_COMMAND_INTRO_ESTABLISHED 38
  #define RELAY_COMMAND_RENDEZVOUS_ESTABLISHED 39
  #define RELAY_COMMAND_INTRODUCE_ACK 40
  
  #define RELAY_COMMAND_PADDING_NEGOTIATE 41
  #define RELAY_COMMAND_PADDING_NEGOTIATED 42
  
  /* Reasons why an OR connection is closed. */
  #define END_OR_CONN_REASON_DONE           1
  #define END_OR_CONN_REASON_REFUSED        2 /* connection refused */
  #define END_OR_CONN_REASON_OR_IDENTITY    3
  #define END_OR_CONN_REASON_CONNRESET      4 /* connection reset by peer */
  #define END_OR_CONN_REASON_TIMEOUT        5
  #define END_OR_CONN_REASON_NO_ROUTE       6 /* no route to host/net */
  #define END_OR_CONN_REASON_IO_ERROR       7 /* read/write error */
  #define END_OR_CONN_REASON_RESOURCE_LIMIT 8 /* sockets, buffers, etc */
  #define END_OR_CONN_REASON_PT_MISSING     9 /* PT failed or not available */
  #define END_OR_CONN_REASON_MISC           10
  
  /* Reasons why we (or a remote OR) might close a stream. See tor-spec.txt for
   * documentation of these.  The values must match. */
  #define END_STREAM_REASON_MISC 1
  #define END_STREAM_REASON_RESOLVEFAILED 2
  #define END_STREAM_REASON_CONNECTREFUSED 3
  #define END_STREAM_REASON_EXITPOLICY 4
  #define END_STREAM_REASON_DESTROY 5
  #define END_STREAM_REASON_DONE 6
  #define END_STREAM_REASON_TIMEOUT 7
  #define END_STREAM_REASON_NOROUTE 8
  #define END_STREAM_REASON_HIBERNATING 9
  #define END_STREAM_REASON_INTERNAL 10
  #define END_STREAM_REASON_RESOURCELIMIT 11
  #define END_STREAM_REASON_CONNRESET 12
  #define END_STREAM_REASON_TORPROTOCOL 13
  #define END_STREAM_REASON_NOTDIRECTORY 14
  #define END_STREAM_REASON_ENTRYPOLICY 15
  
  /* These high-numbered end reasons are not part of the official spec,
   * and are not intended to be put in relay end cells. They are here
   * to be more informative when sending back socks replies to the
   * application. */
  /* XXXX 256 is no longer used; feel free to reuse it. */
  /** We were unable to attach the connection to any circuit at all. */
  /* XXXX the ways we use this one don't make a lot of sense. */
  #define END_STREAM_REASON_CANT_ATTACH 257
  /** We can't connect to any directories at all, so we killed our streams
   * before they can time out. */
  #define END_STREAM_REASON_NET_UNREACHABLE 258
  /** This is a SOCKS connection, and the client used (or misused) the SOCKS
   * protocol in a way we couldn't handle. */
  #define END_STREAM_REASON_SOCKSPROTOCOL 259
  /** This is a transparent proxy connection, but we can't extract the original
   * target address:port. */
  #define END_STREAM_REASON_CANT_FETCH_ORIG_DEST 260
  /** This is a connection on the NATD port, and the destination IP:Port was
   * either ill-formed or out-of-range. */
  #define END_STREAM_REASON_INVALID_NATD_DEST 261
  /** The target address is in a private network (like 127.0.0.1 or 10.0.0.1);
   * you don't want to do that over a randomly chosen exit */
  #define END_STREAM_REASON_PRIVATE_ADDR 262
  /** This is an HTTP tunnel connection and the client used or misused HTTP in a
   * way we can't handle.
   */
  #define END_STREAM_REASON_HTTPPROTOCOL 263
  
  /** Bitwise-and this value with endreason to mask out all flags. */
  #define END_STREAM_REASON_MASK 511
  
  /** Bitwise-or this with the argument to control_event_stream_status
   * to indicate that the reason came from an END cell. */
  #define END_STREAM_REASON_FLAG_REMOTE 512
  /** Bitwise-or this with the argument to control_event_stream_status
   * to indicate that we already sent a CLOSED stream event. */
  #define END_STREAM_REASON_FLAG_ALREADY_SENT_CLOSED 1024
  /** Bitwise-or this with endreason to indicate that we already sent
   * a socks reply, and no further reply needs to be sent from
   * connection_mark_unattached_ap(). */
  #define END_STREAM_REASON_FLAG_ALREADY_SOCKS_REPLIED 2048
  
  /* 'type' values to use in RESOLVED cells.  Specified in tor-spec.txt. */
  #define RESOLVED_TYPE_HOSTNAME 0
  #define RESOLVED_TYPE_IPV4 4
  #define RESOLVED_TYPE_IPV6 6
  #define RESOLVED_TYPE_ERROR_TRANSIENT 0xF0
  #define RESOLVED_TYPE_ERROR 0xF1
  
  /* Negative reasons are internal: we never send them in a DESTROY or TRUNCATE
   * call; they only go to the controller for tracking  */
  
  /* Closing introduction point that were opened in parallel. */
  #define END_CIRC_REASON_IP_NOW_REDUNDANT -4
  
  /** Our post-timeout circuit time measurement period expired.
   * We must give up now */
  #define END_CIRC_REASON_MEASUREMENT_EXPIRED -3
  
  /** We couldn't build a path for this circuit. */
  #define END_CIRC_REASON_NOPATH          -2
  /** Catch-all "other" reason for closing origin circuits. */
  #define END_CIRC_AT_ORIGIN              -1
  
  /* Reasons why we (or a remote OR) might close a circuit. See tor-spec.txt
   * section 5.4 for documentation of these. */
  #define END_CIRC_REASON_MIN_            0
  #define END_CIRC_REASON_NONE            0
  #define END_CIRC_REASON_TORPROTOCOL     1
  #define END_CIRC_REASON_INTERNAL        2
  #define END_CIRC_REASON_REQUESTED       3
  #define END_CIRC_REASON_HIBERNATING     4
  #define END_CIRC_REASON_RESOURCELIMIT   5
  #define END_CIRC_REASON_CONNECTFAILED   6
  #define END_CIRC_REASON_OR_IDENTITY     7
  #define END_CIRC_REASON_CHANNEL_CLOSED  8
  #define END_CIRC_REASON_FINISHED        9
  #define END_CIRC_REASON_TIMEOUT         10
  #define END_CIRC_REASON_DESTROYED       11
  #define END_CIRC_REASON_NOSUCHSERVICE   12
  #define END_CIRC_REASON_MAX_            12
  
  /** Bitwise-OR this with the argument to circuit_mark_for_close() or
   * control_event_circuit_status() to indicate that the reason was
   * passed through from a destroy or truncate cell. */
  #define END_CIRC_REASON_FLAG_REMOTE     512
  
  /** Length of 'y' portion of 'y.onion' URL. */
  #define REND_SERVICE_ID_LEN_BASE32 16
  
  /** Length of 'y.onion' including '.onion' URL. */
  #define REND_SERVICE_ADDRESS_LEN (16+1+5)
  
  /** Length of a binary-encoded rendezvous service ID. */
  #define REND_SERVICE_ID_LEN 10
  
  /** Time period for which a v2 descriptor will be valid. */
  #define REND_TIME_PERIOD_V2_DESC_VALIDITY (24*60*60)
  
  /** Time period within which two sets of v2 descriptors will be uploaded in
   * parallel. */
  #define REND_TIME_PERIOD_OVERLAPPING_V2_DESCS (60*60)
  
  /** Number of non-consecutive replicas (i.e. distributed somewhere
   * in the ring) for a descriptor. */
  #define REND_NUMBER_OF_NON_CONSECUTIVE_REPLICAS 2
  
  /** Number of consecutive replicas for a descriptor. */
  #define REND_NUMBER_OF_CONSECUTIVE_REPLICAS 3
  
  /** Length of v2 descriptor ID (32 base32 chars = 160 bits). */
  #define REND_DESC_ID_V2_LEN_BASE32 BASE32_DIGEST_LEN
  
  /** Length of the base32-encoded secret ID part of versioned hidden service
   * descriptors. */
  #define REND_SECRET_ID_PART_LEN_BASE32 BASE32_DIGEST_LEN
  
  /** Length of the base32-encoded hash of an introduction point's
   * identity key. */
  #define REND_INTRO_POINT_ID_LEN_BASE32 BASE32_DIGEST_LEN
  
  /** Length of the descriptor cookie that is used for client authorization
   * to hidden services. */
  #define REND_DESC_COOKIE_LEN 16
  
  /** Length of the base64-encoded descriptor cookie that is used for
   * exchanging client authorization between hidden service and client. */
  #define REND_DESC_COOKIE_LEN_BASE64 22
  
  /** Length of client identifier in encrypted introduction points for hidden
   * service authorization type 'basic'. */
  #define REND_BASIC_AUTH_CLIENT_ID_LEN 4
  
  /** Multiple of the number of clients to which the real number of clients
   * is padded with fake clients for hidden service authorization type
   * 'basic'. */
  #define REND_BASIC_AUTH_CLIENT_MULTIPLE 16
  
  /** Length of client entry consisting of client identifier and encrypted
   * session key for hidden service authorization type 'basic'. */
  #define REND_BASIC_AUTH_CLIENT_ENTRY_LEN (REND_BASIC_AUTH_CLIENT_ID_LEN \
                                            + CIPHER_KEY_LEN)
  
  /** Maximum size of v2 hidden service descriptors. */
  #define REND_DESC_MAX_SIZE (20 * 1024)
  
  /** Legal characters for use in authorized client names for a hidden
   * service. */
  #define REND_LEGAL_CLIENTNAME_CHARACTERS \
    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+-_"
  
  /** Maximum length of authorized client names for a hidden service. */
  #define REND_CLIENTNAME_MAX_LEN 16
  
  /** Length of the rendezvous cookie that is used to connect circuits at the
   * rendezvous point. */
  #define REND_COOKIE_LEN DIGEST_LEN
  
  /** Client authorization type that a hidden service performs. */
  typedef enum rend_auth_type_t {
    REND_NO_AUTH      = 0,
    REND_BASIC_AUTH   = 1,
    REND_STEALTH_AUTH = 2,
  } rend_auth_type_t;
  
  /** Client-side configuration of authorization for a hidden service. */
  typedef struct rend_service_authorization_t {
    uint8_t descriptor_cookie[REND_DESC_COOKIE_LEN];
    char onion_address[REND_SERVICE_ADDRESS_LEN+1];
    rend_auth_type_t auth_type;
  } rend_service_authorization_t;
  
  /** Client- and server-side data that is used for hidden service connection
   * establishment. Not all fields contain data depending on where this struct
   * is used. */
  typedef struct rend_data_t {
    /* Hidden service protocol version of this base object. */
    uint32_t version;
  
    /** List of HSDir fingerprints on which this request has been sent to. This
     * contains binary identity digest of the directory of size DIGEST_LEN. */
    smartlist_t *hsdirs_fp;
  
    /** Rendezvous cookie used by both, client and service. */
    char rend_cookie[REND_COOKIE_LEN];
  
    /** Number of streams associated with this rendezvous circuit. */
    int nr_streams;
  } rend_data_t;
  
  typedef struct rend_data_v2_t {
    /* Rendezvous base data. */
    rend_data_t base_;
  
    /** Onion address (without the .onion part) that a client requests. */
    char onion_address[REND_SERVICE_ID_LEN_BASE32+1];
  
    /** Descriptor ID for each replicas computed from the onion address. If
     * the onion address is empty, this array MUST be empty. We keep them so
     * we know when to purge our entry in the last hsdir request table. */
    char descriptor_id[REND_NUMBER_OF_NON_CONSECUTIVE_REPLICAS][DIGEST_LEN];
  
    /** (Optional) descriptor cookie that is used by a client. */
    char descriptor_cookie[REND_DESC_COOKIE_LEN];
  
    /** Authorization type for accessing a service used by a client. */
    rend_auth_type_t auth_type;
  
    /** Descriptor ID for a client request. The control port command HSFETCH
     * uses this. It's set if the descriptor query should only use this
     * descriptor ID. */
    char desc_id_fetch[DIGEST_LEN];
  
    /** Hash of the hidden service's PK used by a service. */
    char rend_pk_digest[DIGEST_LEN];
  } rend_data_v2_t;
  
  /* From a base rend_data_t object <b>d</d>, return the v2 object. */
  static inline
  rend_data_v2_t *TO_REND_DATA_V2(const rend_data_t *d)
  {
    tor_assert(d);
    tor_assert(d->version == 2);
    return DOWNCAST(rend_data_v2_t, d);
  }
  
  /* Stub because we can't include hs_ident.h. */
  struct hs_ident_edge_conn_t;
  struct hs_ident_dir_conn_t;
  struct hs_ident_circuit_t;
  
  typedef struct hsdir_index_t hsdir_index_t;
  
  /** Time interval for tracking replays of DH public keys received in
   * INTRODUCE2 cells.  Used only to avoid launching multiple
   * simultaneous attempts to connect to the same rendezvous point. */
  #define REND_REPLAY_TIME_INTERVAL (5 * 60)
  
  /** Used to indicate which way a cell is going on a circuit. */
  typedef enum {
    CELL_DIRECTION_IN=1, /**< The cell is moving towards the origin. */
    CELL_DIRECTION_OUT=2, /**< The cell is moving away from the origin. */
  } cell_direction_t;
  
  /**
   * An enum to allow us to specify which channel in a circuit
   * we're interested in.
   *
   * This is needed because our data structures and other fields
   * for channel delivery are disassociated from the channel.
   */
  typedef enum {
    CIRCUIT_N_CHAN = 0,
    CIRCUIT_P_CHAN = 1
  } circuit_channel_direction_t;
  
  /** Initial value for both sides of a circuit transmission window when the
   * circuit is initialized.  Measured in cells. */
  #define CIRCWINDOW_START 1000
  #define CIRCWINDOW_START_MIN 100
  #define CIRCWINDOW_START_MAX 1000
  /** Amount to increment a circuit window when we get a circuit SENDME. */
  #define CIRCWINDOW_INCREMENT 100
  /** Initial value on both sides of a stream transmission window when the
   * stream is initialized.  Measured in cells. */
  #define STREAMWINDOW_START 500
  #define STREAMWINDOW_START_MAX 500
  /** Amount to increment a stream window when we get a stream SENDME. */
  #define STREAMWINDOW_INCREMENT 50
  
  /** Maximum number of queued cells on a circuit for which we are the
   * midpoint before we give up and kill it.  This must be >= circwindow
   * to avoid killing innocent circuits, and >= circwindow*2 to give
   * leaky-pipe a chance of working someday. The ORCIRC_MAX_MIDDLE_KILL_THRESH
   * ratio controls the margin of error between emitting a warning and
   * killing the circuit.
   */
  #define ORCIRC_MAX_MIDDLE_CELLS (CIRCWINDOW_START_MAX*2)
  /** Ratio of hard (circuit kill) to soft (warning) thresholds for the
   * ORCIRC_MAX_MIDDLE_CELLS tests.
   */
  #define ORCIRC_MAX_MIDDLE_KILL_THRESH (1.1f)
  
  /* Cell commands.  These values are defined in tor-spec.txt. */
  #define CELL_PADDING 0
  #define CELL_CREATE 1
  #define CELL_CREATED 2
  #define CELL_RELAY 3
  #define CELL_DESTROY 4
  #define CELL_CREATE_FAST 5
  #define CELL_CREATED_FAST 6
  #define CELL_VERSIONS 7
  #define CELL_NETINFO 8
  #define CELL_RELAY_EARLY 9
  #define CELL_CREATE2 10
  #define CELL_CREATED2 11
  #define CELL_PADDING_NEGOTIATE 12
  
  #define CELL_VPADDING 128
  #define CELL_CERTS 129
  #define CELL_AUTH_CHALLENGE 130
  #define CELL_AUTHENTICATE 131
  #define CELL_AUTHORIZE 132
  #define CELL_COMMAND_MAX_ 132
  
  /** How long to test reachability before complaining to the user. */
  #define TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT (20*60)
  
  /** Legal characters in a nickname. */
  #define LEGAL_NICKNAME_CHARACTERS \
    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
  
  /** Name to use in client TLS certificates if no nickname is given. Once
   * Tor 0.1.2.x is obsolete, we can remove this. */
  #define DEFAULT_CLIENT_NICKNAME "client"
  
  /** Name chosen by routers that don't configure nicknames */
  #define UNNAMED_ROUTER_NICKNAME "Unnamed"
  
  /** Number of bytes in a SOCKS4 header. */
  #define SOCKS4_NETWORK_LEN 8
  
  /*
   * Relay payload:
   *         Relay command           [1 byte]
   *         Recognized              [2 bytes]
   *         Stream ID               [2 bytes]
   *         Partial SHA-1           [4 bytes]
   *         Length                  [2 bytes]
   *         Relay payload           [498 bytes]
   */
  
  /** Number of bytes in a cell, minus cell header. */
  #define CELL_PAYLOAD_SIZE 509
  /** Number of bytes in a cell transmitted over the network, in the longest
   * form */
  #define CELL_MAX_NETWORK_SIZE 514
  
  /** Maximum length of a header on a variable-length cell. */
  #define VAR_CELL_MAX_HEADER_SIZE 7
  
  static int get_cell_network_size(int wide_circ_ids);
  static inline int get_cell_network_size(int wide_circ_ids)
  {
    return wide_circ_ids ? CELL_MAX_NETWORK_SIZE : CELL_MAX_NETWORK_SIZE - 2;
  }
  static int get_var_cell_header_size(int wide_circ_ids);
  static inline int get_var_cell_header_size(int wide_circ_ids)
  {
    return wide_circ_ids ? VAR_CELL_MAX_HEADER_SIZE :
      VAR_CELL_MAX_HEADER_SIZE - 2;
  }
  static int get_circ_id_size(int wide_circ_ids);
  static inline int get_circ_id_size(int wide_circ_ids)
  {
    return wide_circ_ids ? 4 : 2;
  }
  
  /** Number of bytes in a relay cell's header (not including general cell
   * header). */
  #define RELAY_HEADER_SIZE (1+2+2+4+2)
  /** Largest number of bytes that can fit in a relay cell payload. */
  #define RELAY_PAYLOAD_SIZE (CELL_PAYLOAD_SIZE-RELAY_HEADER_SIZE)
  
  /** Identifies a circuit on an or_connection */
  typedef uint32_t circid_t;
  /** Identifies a stream on a circuit */
  typedef uint16_t streamid_t;
  
  /* channel_t typedef; struct channel_t is in channel.h */
  
  typedef struct channel_t channel_t;
  
  /* channel_listener_t typedef; struct channel_listener_t is in channel.h */
  
  typedef struct channel_listener_t channel_listener_t;
  
  /* TLS channel stuff */
  
  typedef struct channel_tls_t channel_tls_t;
  
  /* circuitmux_t typedef; struct circuitmux_t is in circuitmux.h */
  
  typedef struct circuitmux_t circuitmux_t;
  
  typedef struct cell_t cell_t;
  typedef struct var_cell_t var_cell_t;
  typedef struct packed_cell_t packed_cell_t;
  typedef struct cell_queue_t cell_queue_t;
  typedef struct destroy_cell_t destroy_cell_t;
  typedef struct destroy_cell_queue_t destroy_cell_queue_t;
  typedef struct ext_or_cmd_t ext_or_cmd_t;
  
  /** Beginning of a RELAY cell payload. */
  typedef struct {
    uint8_t command; /**< The end-to-end relay command. */
    uint16_t recognized; /**< Used to tell whether cell is for us. */
    streamid_t stream_id; /**< Which stream is this cell associated with? */
    char integrity[4]; /**< Used to tell whether cell is corrupted. */
    uint16_t length; /**< How long is the payload body? */
  } relay_header_t;
  
  typedef struct socks_request_t socks_request_t;
  typedef struct entry_port_cfg_t entry_port_cfg_t;
  typedef struct server_port_cfg_t server_port_cfg_t;
  
  /** Minimum length of the random part of an AUTH_CHALLENGE cell. */
  #define OR_AUTH_CHALLENGE_LEN 32
  
  /**
   * @name Certificate types for CERTS cells.
   *
   * These values are defined by the protocol, and affect how an X509
   * certificate in a CERTS cell is interpreted and used.
   *
   * @{ */
  /** A certificate that authenticates a TLS link key.  The subject key
   * must match the key used in the TLS handshake; it must be signed by
   * the identity key. */
  #define OR_CERT_TYPE_TLS_LINK 1
  /** A self-signed identity certificate. The subject key must be a
   * 1024-bit RSA key. */
  #define OR_CERT_TYPE_ID_1024 2
  /** A certificate that authenticates a key used in an AUTHENTICATE cell
   * in the v3 handshake.  The subject key must be a 1024-bit RSA key; it
   * must be signed by the identity key */
  #define OR_CERT_TYPE_AUTH_1024 3
  /* DOCDOC */
  #define OR_CERT_TYPE_RSA_ED_CROSSCERT 7
  /**@}*/
  
  /** The first supported type of AUTHENTICATE cell.  It contains
   * a bunch of structures signed with an RSA1024 key.  The signed
   * structures include a HMAC using negotiated TLS secrets, and a digest
   * of all cells sent or received before the AUTHENTICATE cell (including
   * the random server-generated AUTH_CHALLENGE cell).
   */
  #define AUTHTYPE_RSA_SHA256_TLSSECRET 1
  /** As AUTHTYPE_RSA_SHA256_TLSSECRET, but instead of using the
   * negotiated TLS secrets, uses exported keying material from the TLS
   * session as described in RFC 5705.
   *
   * Not used by today's tors, since everything that supports this
   * also supports ED25519_SHA256_5705, which is better.
   **/
  #define AUTHTYPE_RSA_SHA256_RFC5705 2
  /** As AUTHTYPE_RSA_SHA256_RFC5705, but uses an Ed25519 identity key to
   * authenticate.  */
  #define AUTHTYPE_ED25519_SHA256_RFC5705 3
  /*
   * NOTE: authchallenge_type_is_better() relies on these AUTHTYPE codes
   * being sorted in order of preference.  If we someday add one with
   * a higher numerical value that we don't like as much, we should revise
   * authchallenge_type_is_better().
   */
  
  /** The length of the part of the AUTHENTICATE cell body that the client and
   * server can generate independently (when using RSA_SHA256_TLSSECRET). It
   * contains everything except the client's timestamp, the client's randomly
   * generated nonce, and the signature. */
  #define V3_AUTH_FIXED_PART_LEN (8+(32*6))
  /** The length of the part of the AUTHENTICATE cell body that the client
   * signs. */
  #define V3_AUTH_BODY_LEN (V3_AUTH_FIXED_PART_LEN + 8 + 16)
  
  typedef struct or_handshake_certs_t or_handshake_certs_t;
  typedef struct or_handshake_state_t or_handshake_state_t;
  
  /** Length of Extended ORPort connection identifier. */
  #define EXT_OR_CONN_ID_LEN DIGEST_LEN /* 20 */
  /*
   * OR_CONN_HIGHWATER and OR_CONN_LOWWATER moved from connection_or.c so
   * channeltls.c can see them too.
   */
  
  /** When adding cells to an OR connection's outbuf, keep adding until the
   * outbuf is at least this long, or we run out of cells. */
  #define OR_CONN_HIGHWATER (32*1024)
  
  /** Add cells to an OR connection's outbuf whenever the outbuf's data length
   * drops below this size. */
  #define OR_CONN_LOWWATER (16*1024)
  
  typedef struct connection_t connection_t;
  typedef struct control_connection_t control_connection_t;
  typedef struct dir_connection_t dir_connection_t;
  typedef struct edge_connection_t edge_connection_t;
  typedef struct entry_connection_t entry_connection_t;
  typedef struct listener_connection_t listener_connection_t;
  typedef struct or_connection_t or_connection_t;
  
  /** Cast a connection_t subtype pointer to a connection_t **/
  #define TO_CONN(c) (&(((c)->base_)))
  
  /** Cast a entry_connection_t subtype pointer to a connection_t **/
  #define ENTRY_TO_CONN(c) (TO_CONN(ENTRY_TO_EDGE_CONN(c)))
  
  typedef struct addr_policy_t addr_policy_t;
  
  typedef struct cached_dir_t cached_dir_t;
  
  /** Enum used to remember where a signed_descriptor_t is stored and how to
   * manage the memory for signed_descriptor_body.  */
  typedef enum {
    /** The descriptor isn't stored on disk at all: the copy in memory is
     * canonical; the saved_offset field is meaningless. */
    SAVED_NOWHERE=0,
    /** The descriptor is stored in the cached_routers file: the
     * signed_descriptor_body is meaningless; the signed_descriptor_len and
     * saved_offset are used to index into the mmaped cache file. */
    SAVED_IN_CACHE,
    /** The descriptor is stored in the cached_routers.new file: the
     * signed_descriptor_body and saved_offset fields are both set. */
    /* FFFF (We could also mmap the file and grow the mmap as needed, or
     * lazy-load the descriptor text by using seek and read.  We don't, for
     * now.)
     */
    SAVED_IN_JOURNAL
  } saved_location_t;
  #define saved_location_bitfield_t ENUM_BF(saved_location_t)
  
  /** Enumeration: what directory object is being downloaded?
   * This determines which schedule is selected to perform the download. */
  typedef enum {
    DL_SCHED_GENERIC = 0,
    DL_SCHED_CONSENSUS = 1,
    DL_SCHED_BRIDGE = 2,
  } download_schedule_t;
  #define download_schedule_bitfield_t ENUM_BF(download_schedule_t)
  
  /** Enumeration: is the download schedule for downloading from an authority,
   * or from any available directory mirror?
   * During bootstrap, "any" means a fallback (or an authority, if there
   * are no fallbacks).
   * When we have a valid consensus, "any" means any directory server. */
  typedef enum {
    DL_WANT_ANY_DIRSERVER = 0,
    DL_WANT_AUTHORITY = 1,
  } download_want_authority_t;
  #define download_want_authority_bitfield_t \
                                          ENUM_BF(download_want_authority_t)
  
  /** Enumeration: do we want to increment the schedule position each time a
   * connection is attempted (these attempts can be concurrent), or do we want
   * to increment the schedule position after a connection fails? */
  typedef enum {
    DL_SCHED_INCREMENT_FAILURE = 0,
    DL_SCHED_INCREMENT_ATTEMPT = 1,
  } download_schedule_increment_t;
  #define download_schedule_increment_bitfield_t \
                                          ENUM_BF(download_schedule_increment_t)
  
  typedef struct download_status_t download_status_t;
  
  /** If n_download_failures is this high, the download can never happen. */
  #define IMPOSSIBLE_TO_DOWNLOAD 255
  
  /** The max size we expect router descriptor annotations we create to
   * be. We'll accept larger ones if we see them on disk, but we won't
   * create any that are larger than this. */
  #define ROUTER_ANNOTATION_BUF_LEN 256
  
  typedef struct signed_descriptor_t signed_descriptor_t;
  
  /** Flags used to summarize the declared protocol versions of a relay,
   * so we don't need to parse them again and again. */
  typedef struct protover_summary_flags_t {
    /** True iff we have a proto line for this router, or a versions line
     * from which we could infer the protocols. */
    unsigned int protocols_known:1;
  
    /** True iff this router has a version or protocol list that allows it to
     * accept EXTEND2 cells. This requires Relay=2. */
    unsigned int supports_extend2_cells:1;
  
    /** True iff this router has a protocol list that allows it to negotiate
     * ed25519 identity keys on a link handshake with us. This
     * requires LinkAuth=3. */
    unsigned int supports_ed25519_link_handshake_compat:1;
  
    /** True iff this router has a protocol list that allows it to negotiate
     * ed25519 identity keys on a link handshake, at all. This requires some
     * LinkAuth=X for X >= 3. */
    unsigned int supports_ed25519_link_handshake_any:1;
  
    /** True iff this router has a protocol list that allows it to be an
     * introduction point supporting ed25519 authentication key which is part of
     * the v3 protocol detailed in proposal 224. This requires HSIntro=4. */
    unsigned int supports_ed25519_hs_intro : 1;
  
    /** True iff this router has a protocol list that allows it to be an hidden
     * service directory supporting version 3 as seen in proposal 224. This
     * requires HSDir=2. */
    unsigned int supports_v3_hsdir : 1;
  
    /** True iff this router has a protocol list that allows it to be an hidden
     * service rendezvous point supporting version 3 as seen in proposal 224.
     * This requires HSRend=2. */
    unsigned int supports_v3_rendezvous_point: 1;
  
    /** True iff this router has a protocol list that allows clients to
     * negotiate hs circuit setup padding. Requires Padding>=2. */
    unsigned int supports_hs_setup_padding : 1;
  
    /** True iff this router has a protocol list that allows it to support the
     * ESTABLISH_INTRO DoS cell extension. Requires HSIntro>=5. */
    unsigned int supports_establish_intro_dos_extension : 1;
  } protover_summary_flags_t;
  
  typedef struct routerinfo_t routerinfo_t;
  typedef struct extrainfo_t extrainfo_t;
  typedef struct routerstatus_t routerstatus_t;
  
  typedef struct microdesc_t microdesc_t;
  typedef struct node_t node_t;
  typedef struct vote_microdesc_hash_t vote_microdesc_hash_t;
  typedef struct vote_routerstatus_t vote_routerstatus_t;
  typedef struct document_signature_t document_signature_t;
  typedef struct networkstatus_voter_info_t networkstatus_voter_info_t;
  typedef struct networkstatus_sr_info_t networkstatus_sr_info_t;
  
  /** Enumerates recognized flavors of a consensus networkstatus document.  All
   * flavors of a consensus are generated from the same set of votes, but they
   * present different types information to different versions of Tor. */
  typedef enum {
    FLAV_NS = 0,
    FLAV_MICRODESC = 1,
  } consensus_flavor_t;
  
  /** How many different consensus flavors are there? */
  #define N_CONSENSUS_FLAVORS ((int)(FLAV_MICRODESC)+1)
  
  typedef struct networkstatus_t networkstatus_t;
  typedef struct ns_detached_signatures_t ns_detached_signatures_t;
  typedef struct desc_store_t desc_store_t;
  typedef struct routerlist_t routerlist_t;
  typedef struct extend_info_t extend_info_t;
  typedef struct authority_cert_t authority_cert_t;
  
  /** Bitfield enum type listing types of information that directory authorities
   * can be authoritative about, and that directory caches may or may not cache.
   *
   * Note that the granularity here is based on authority granularity and on
   * cache capabilities.  Thus, one particular bit may correspond in practice to
   * a few types of directory info, so long as every authority that pronounces
   * officially about one of the types prounounces officially about all of them,
   * and so long as every cache that caches one of them caches all of them.
   */
  typedef enum {
    NO_DIRINFO      = 0,
    /** Serves/signs v3 directory information: votes, consensuses, certs */
    V3_DIRINFO      = 1 << 2,
    /** Serves bridge descriptors. */
    BRIDGE_DIRINFO  = 1 << 4,
    /** Serves extrainfo documents. */
    EXTRAINFO_DIRINFO=1 << 5,
    /** Serves microdescriptors. */
    MICRODESC_DIRINFO=1 << 6,
  } dirinfo_type_t;
  
  #define ALL_DIRINFO ((dirinfo_type_t)((1<<7)-1))
  
  #define ONION_HANDSHAKE_TYPE_TAP  0x0000
  #define ONION_HANDSHAKE_TYPE_FAST 0x0001
  #define ONION_HANDSHAKE_TYPE_NTOR 0x0002
  #define MAX_ONION_HANDSHAKE_TYPE 0x0002
  
  typedef struct onion_handshake_state_t onion_handshake_state_t;
  typedef struct relay_crypto_t relay_crypto_t;
  typedef struct crypt_path_t crypt_path_t;
  typedef struct crypt_path_reference_t crypt_path_reference_t;
  
  #define CPATH_KEY_MATERIAL_LEN (20*2+16*2)
  
  typedef struct cpath_build_state_t cpath_build_state_t;
  
  struct create_cell_t;
  
  /** Entry in the cell stats list of a circuit; used only if CELL_STATS
   * events are enabled. */
  typedef struct testing_cell_stats_entry_t {
    uint8_t command; /**< cell command number. */
    /** Waiting time in centiseconds if this event is for a removed cell,
     * or 0 if this event is for adding a cell to the queue.  22 bits can
     * store more than 11 hours, enough to assume that a circuit with this
     * delay would long have been closed. */
    unsigned int waiting_time:22;
    unsigned int removed:1; /**< 0 for added to, 1 for removed from queue. */
    unsigned int exitward:1; /**< 0 for app-ward, 1 for exit-ward. */
  } testing_cell_stats_entry_t;
  
  typedef struct circuit_t circuit_t;
  typedef struct origin_circuit_t origin_circuit_t;
  typedef struct or_circuit_t or_circuit_t;
  
  /** Largest number of relay_early cells that we can send on a given
   * circuit. */
  #define MAX_RELAY_EARLY_CELLS_PER_CIRCUIT 8
  
  typedef enum path_state_t path_state_t;
  #define path_state_bitfield_t ENUM_BF(path_state_t)
  
  #if REND_COOKIE_LEN != DIGEST_LEN
  #error "The REND_TOKEN_LEN macro assumes REND_COOKIE_LEN == DIGEST_LEN"
  #endif
  #define REND_TOKEN_LEN DIGEST_LEN
  
  /** Convert a circuit subtype to a circuit_t. */
  #define TO_CIRCUIT(x)  (&((x)->base_))
  
  /** @name Isolation flags
  
      Ways to isolate client streams
  
      @{
  */
  /** Isolate based on destination port */
  #define ISO_DESTPORT    (1u<<0)
  /** Isolate based on destination address */
  #define ISO_DESTADDR    (1u<<1)
  /** Isolate based on SOCKS authentication */
  #define ISO_SOCKSAUTH   (1u<<2)
  /** Isolate based on client protocol choice */
  #define ISO_CLIENTPROTO (1u<<3)
  /** Isolate based on client address */
  #define ISO_CLIENTADDR  (1u<<4)
  /** Isolate based on session group (always on). */
  #define ISO_SESSIONGRP  (1u<<5)
  /** Isolate based on newnym epoch (always on). */
  #define ISO_NYM_EPOCH   (1u<<6)
  /** Isolate all streams (Internal only). */
  #define ISO_STREAM      (1u<<7)
  /**@}*/
  
  /** Default isolation level for ports. */
  #define ISO_DEFAULT (ISO_CLIENTADDR|ISO_SOCKSAUTH|ISO_SESSIONGRP|ISO_NYM_EPOCH)
  
  /** Indicates that we haven't yet set a session group on a port_cfg_t. */
  #define SESSION_GROUP_UNSET -1
  /** Session group reserved for directory connections */
  #define SESSION_GROUP_DIRCONN -2
  /** Session group reserved for resolve requests launched by a controller */
  #define SESSION_GROUP_CONTROL_RESOLVE -3
  /** First automatically allocated session group number */
  #define SESSION_GROUP_FIRST_AUTO -4
  
  typedef struct port_cfg_t port_cfg_t;
  typedef struct routerset_t routerset_t;
  
  /** A magic value for the (Socks|OR|...)Port options below, telling Tor
   * to pick its own port. */
  #define CFG_AUTO_PORT 0xc4005e
  
  typedef struct or_options_t or_options_t;
  
  #define LOG_PROTOCOL_WARN (get_protocol_warning_severity_level())
  
  typedef struct or_state_t or_state_t;
  
  #define MAX_SOCKS_ADDR_LEN 256
  
  /********************************* circuitbuild.c **********************/
  
  /** How many hops does a general-purpose circuit have by default? */
  #define DEFAULT_ROUTE_LEN 2
  
  /* Circuit Build Timeout "public" structures. */
  
  /** Precision multiplier for the Bw weights */
  #define BW_WEIGHT_SCALE   10000
  #define BW_MIN_WEIGHT_SCALE 1
  #define BW_MAX_WEIGHT_SCALE INT32_MAX
  
  typedef struct circuit_build_times_t circuit_build_times_t;
  
  /********************************* config.c ***************************/
  
  /********************************* connection_edge.c *************************/
  
  /** Enumerates possible origins of a client-side address mapping. */
  typedef enum {
    /** We're remapping this address because the controller told us to. */
    ADDRMAPSRC_CONTROLLER,
    /** We're remapping this address because of an AutomapHostsOnResolve
     * configuration. */
    ADDRMAPSRC_AUTOMAP,
    /** We're remapping this address because our configuration (via torrc, the
     * command line, or a SETCONF command) told us to. */
    ADDRMAPSRC_TORRC,
    /** We're remapping this address because we have TrackHostExit configured,
     * and we want to remember to use the same exit next time. */
    ADDRMAPSRC_TRACKEXIT,
    /** We're remapping this address because we got a DNS resolution from a
     * Tor server that told us what its value was. */
    ADDRMAPSRC_DNS,
  
    /** No remapping has occurred.  This isn't a possible value for an
     * addrmap_entry_t; it's used as a null value when we need to answer "Why
     * did this remapping happen." */
    ADDRMAPSRC_NONE
  } addressmap_entry_source_t;
  #define addressmap_entry_source_bitfield_t ENUM_BF(addressmap_entry_source_t)
  
  #define WRITE_STATS_INTERVAL (24*60*60)
  
  /********************************* dirvote.c ************************/
  
  typedef struct vote_timing_t vote_timing_t;
  
  /********************************* microdesc.c *************************/
  
  typedef struct microdesc_cache_t microdesc_cache_t;
  
  /********************************* rendcommon.c ***************************/
  
  typedef struct rend_authorized_client_t rend_authorized_client_t;
  typedef struct rend_encoded_v2_service_descriptor_t
                 rend_encoded_v2_service_descriptor_t;
  
  /** The maximum number of non-circuit-build-timeout failures a hidden
   * service client will tolerate while trying to build a circuit to an
   * introduction point.  See also rend_intro_point_t.unreachable_count. */
  #define MAX_INTRO_POINT_REACHABILITY_FAILURES 5
  
  /** The minimum and maximum number of distinct INTRODUCE2 cells which a
   * hidden service's introduction point will receive before it begins to
   * expire. */
  #define INTRO_POINT_MIN_LIFETIME_INTRODUCTIONS 16384
  /* Double the minimum value so the interval is [min, min * 2]. */
  #define INTRO_POINT_MAX_LIFETIME_INTRODUCTIONS \
    (INTRO_POINT_MIN_LIFETIME_INTRODUCTIONS * 2)
  
  /** The minimum number of seconds that an introduction point will last
   * before expiring due to old age.  (If it receives
   * INTRO_POINT_LIFETIME_INTRODUCTIONS INTRODUCE2 cells, it may expire
   * sooner.)
   *
   * XXX Should this be configurable? */
  #define INTRO_POINT_LIFETIME_MIN_SECONDS (18*60*60)
  /** The maximum number of seconds that an introduction point will last
   * before expiring due to old age.
   *
   * XXX Should this be configurable? */
  #define INTRO_POINT_LIFETIME_MAX_SECONDS (24*60*60)
  
  /** The maximum number of circuit creation retry we do to an intro point
   * before giving up. We try to reuse intro point that fails during their
   * lifetime so this is a hard limit on the amount of time we do that. */
  #define MAX_INTRO_POINT_CIRCUIT_RETRIES 3
  
  typedef struct rend_intro_point_t rend_intro_point_t;
  typedef struct rend_service_descriptor_t rend_service_descriptor_t;
  
  /********************************* routerlist.c ***************************/
  
  typedef struct dir_server_t dir_server_t;
  
  #define RELAY_REQUIRED_MIN_BANDWIDTH (75*1024)
  #define BRIDGE_REQUIRED_MIN_BANDWIDTH (50*1024)
  
  #define ROUTER_MAX_DECLARED_BANDWIDTH INT32_MAX
  
  typedef struct tor_version_t tor_version_t;
  
  #endif /* !defined(TOR_OR_H) */
  