text: /*
   * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014 Nicira, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at:
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include <config.h>
  #include "stream-ssl.h"
  #include "dhparams.h"
  #include <ctype.h>
  #include <errno.h>
  #include <inttypes.h>
  #include <string.h>
  #include <sys/types.h>
  #include <sys/socket.h>
  #include <netinet/tcp.h>
  #include <openssl/err.h>
  #include <openssl/rand.h>
  #include <openssl/ssl.h>
  #include <openssl/x509v3.h>
  #include <poll.h>
  #include <fcntl.h>
  #include <sys/stat.h>
  #include <unistd.h>
  #include "coverage.h"
  #include "dynamic-string.h"
  #include "entropy.h"
  #include "ofpbuf.h"
  #include "openflow/openflow.h"
  #include "packets.h"
  #include "poll-loop.h"
  #include "shash.h"
  #include "socket-util.h"
  #include "util.h"
  #include "stream-provider.h"
  #include "stream.h"
  #include "timeval.h"
  #include "vlog.h"
  
  #ifdef _WIN32
  /* Ref: https://www.openssl.org/support/faq.html#PROG2
   * Your application must link against the same version of the Win32 C-Runtime
   * against which your openssl libraries were linked.  The default version for
   * OpenSSL is /MD - "Multithreaded DLL". If we compile Open vSwitch with
   * something other than /MD, instead of re-compiling OpenSSL
   * toolkit, openssl/applink.c can be #included. Also, it is important
   * to add CRYPTO_malloc_init prior first call to OpenSSL.
   *
   * XXX: The behavior of the following #include when Open vSwitch is
   * compiled with /MD is not tested. */
  #include <openssl/applink.c>
  #define SHUT_RDWR SD_BOTH
  #endif
  
  VLOG_DEFINE_THIS_MODULE(stream_ssl);
  
  /* Active SSL. */
  
  enum ssl_state {
      STATE_TCP_CONNECTING,
      STATE_SSL_CONNECTING
  };
  
  enum session_type {
      CLIENT,
      SERVER
  };
  
  struct ssl_stream
  {
      struct stream stream;
      enum ssl_state state;
      enum session_type type;
      int fd;
      SSL *ssl;
      struct ofpbuf *txbuf;
      unsigned int session_nr;
  
      /* rx_want and tx_want record the result of the last call to SSL_read()
       * and SSL_write(), respectively:
       *
       *    - If the call reported that data needed to be read from the file
       *      descriptor, the corresponding member is set to SSL_READING.
       *
       *    - If the call reported that data needed to be written to the file
       *      descriptor, the corresponding member is set to SSL_WRITING.
       *
       *    - Otherwise, the member is set to SSL_NOTHING, indicating that the
       *      call completed successfully (or with an error) and that there is no
       *      need to block.
       *
       * These are needed because there is no way to ask OpenSSL what a data read
       * or write would require without giving it a buffer to receive into or
       * data to send, respectively.  (Note that the SSL_want() status is
       * overwritten by each SSL_read() or SSL_write() call, so we can't rely on
       * its value.)
       *
       * A single call to SSL_read() or SSL_write() can perform both reading
       * and writing and thus invalidate not one of these values but actually
       * both.  Consider this situation, for example:
       *
       *    - SSL_write() blocks on a read, so tx_want gets SSL_READING.
       *
       *    - SSL_read() laters succeeds reading from 'fd' and clears out the
       *      whole receive buffer, so rx_want gets SSL_READING.
       *
       *    - Client calls stream_wait(STREAM_RECV) and stream_wait(STREAM_SEND)
       *      and blocks.
       *
       *    - Now we're stuck blocking until the peer sends us data, even though
       *      SSL_write() could now succeed, which could easily be a deadlock
       *      condition.
       *
       * On the other hand, we can't reset both tx_want and rx_want on every call
       * to SSL_read() or SSL_write(), because that would produce livelock,
       * e.g. in this situation:
       *
       *    - SSL_write() blocks, so tx_want gets SSL_READING or SSL_WRITING.
       *
       *    - SSL_read() blocks, so rx_want gets SSL_READING or SSL_WRITING,
       *      but tx_want gets reset to SSL_NOTHING.
       *
       *    - Client calls stream_wait(STREAM_RECV) and stream_wait(STREAM_SEND)
       *      and blocks.
       *
       *    - Client wakes up immediately since SSL_NOTHING in tx_want indicates
       *      that no blocking is necessary.
       *
       * The solution we adopt here is to set tx_want to SSL_NOTHING after
       * calling SSL_read() only if the SSL state of the connection changed,
       * which indicates that an SSL-level renegotiation made some progress, and
       * similarly for rx_want and SSL_write().  This prevents both the
       * deadlock and livelock situations above.
       */
      int rx_want, tx_want;
  
      /* A few bytes of header data in case SSL negotiation fails. */
      uint8_t head[2];
      short int n_head;
  };
  
  /* SSL context created by ssl_init(). */
  static SSL_CTX *ctx;
  
  struct ssl_config_file {
      bool read;                  /* Whether the file was successfully read. */
      char *file_name;            /* Configured file name, if any. */
      struct timespec mtime;      /* File mtime as of last time we read it. */
  };
  
  /* SSL configuration files. */
  static struct ssl_config_file private_key;
  static struct ssl_config_file certificate;
  static struct ssl_config_file ca_cert;
  
  /* Ordinarily, the SSL client and server verify each other's certificates using
   * a CA certificate.  Setting this to false disables this behavior.  (This is a
   * security risk.) */
  static bool verify_peer_cert = true;
  
  /* Ordinarily, we require a CA certificate for the peer to be locally
   * available.  We can, however, bootstrap the CA certificate from the peer at
   * the beginning of our first connection then use that certificate on all
   * subsequent connections, saving it to a file for use in future runs also.  In
   * this case, 'bootstrap_ca_cert' is true. */
  static bool bootstrap_ca_cert;
  
  /* Session number.  Used in debug logging messages to uniquely identify a
   * session. */
  static unsigned int next_session_nr;
  
  /* Who knows what can trigger various SSL errors, so let's throttle them down
   * quite a bit. */
  static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 25);
  
  static int ssl_init(void);
  static int do_ssl_init(void);
  static bool ssl_wants_io(int ssl_error);
  static void ssl_close(struct stream *);
  static void ssl_clear_txbuf(struct ssl_stream *);
  static void interpret_queued_ssl_error(const char *function);
  static int interpret_ssl_error(const char *function, int ret, int error,
                                 int *want);
  static DH *tmp_dh_callback(SSL *ssl, int is_export OVS_UNUSED, int keylength);
  static void log_ca_cert(const char *file_name, X509 *cert);
  static void stream_ssl_set_ca_cert_file__(const char *file_name,
                                            bool bootstrap, bool force);
  static void ssl_protocol_cb(int write_p, int version, int content_type,
                              const void *, size_t, SSL *, void *sslv_);
  static bool update_ssl_config(struct ssl_config_file *, const char *file_name);
  static int sock_errno(void);
  
  static short int
  want_to_poll_events(int want)
  {
      switch (want) {
      case SSL_NOTHING:
          OVS_NOT_REACHED();
  
      case SSL_READING:
          return POLLIN;
  
      case SSL_WRITING:
          return POLLOUT;
  
      default:
          OVS_NOT_REACHED();
      }
  }
  
  static int
  new_ssl_stream(const char *name, int fd, enum session_type type,
                 enum ssl_state state, struct stream **streamp)
  {
      struct ssl_stream *sslv;
      SSL *ssl = NULL;
      int retval;
  
      /* Check for all the needful configuration. */
      retval = 0;
      if (!private_key.read) {
          VLOG_ERR("Private key must be configured to use SSL");
          retval = ENOPROTOOPT;
      }
      if (!certificate.read) {
          VLOG_ERR("Certificate must be configured to use SSL");
          retval = ENOPROTOOPT;
      }
      if (!ca_cert.read && verify_peer_cert && !bootstrap_ca_cert) {
          VLOG_ERR("CA certificate must be configured to use SSL");
          retval = ENOPROTOOPT;
      }
      if (!retval && !SSL_CTX_check_private_key(ctx)) {
          VLOG_ERR("Private key does not match certificate public key: %s",
                   ERR_error_string(ERR_get_error(), NULL));
          retval = ENOPROTOOPT;
      }
      if (retval) {
          goto error;
      }
  
      /* Disable Nagle.
       * On windows platforms, this can only be called upon TCP connected.
       */
      if (state == STATE_SSL_CONNECTING) {
          setsockopt_tcp_nodelay(fd);
      }
  
      /* Create and configure OpenSSL stream. */
      ssl = SSL_new(ctx);
      if (ssl == NULL) {
          VLOG_ERR("SSL_new: %s", ERR_error_string(ERR_get_error(), NULL));
          retval = ENOPROTOOPT;
          goto error;
      }
      if (SSL_set_fd(ssl, fd) == 0) {
          VLOG_ERR("SSL_set_fd: %s", ERR_error_string(ERR_get_error(), NULL));
          retval = ENOPROTOOPT;
          goto error;
      }
      if (!verify_peer_cert || (bootstrap_ca_cert && type == CLIENT)) {
          SSL_set_verify(ssl, SSL_VERIFY_NONE, NULL);
      }
  
      /* Create and return the ssl_stream. */
      sslv = xmalloc(sizeof *sslv);
      stream_init(&sslv->stream, &ssl_stream_class, EAGAIN, name);
      sslv->state = state;
      sslv->type = type;
      sslv->fd = fd;
      sslv->ssl = ssl;
      sslv->txbuf = NULL;
      sslv->rx_want = sslv->tx_want = SSL_NOTHING;
      sslv->session_nr = next_session_nr++;
      sslv->n_head = 0;
  
      if (VLOG_IS_DBG_ENABLED()) {
          SSL_set_msg_callback(ssl, ssl_protocol_cb);
          SSL_set_msg_callback_arg(ssl, sslv);
      }
  
      *streamp = &sslv->stream;
      return 0;
  
  error:
      if (ssl) {
          SSL_free(ssl);
      }
      closesocket(fd);
      return retval;
  }
  
  static struct ssl_stream *
  ssl_stream_cast(struct stream *stream)
  {
      stream_assert_class(stream, &ssl_stream_class);
      return CONTAINER_OF(stream, struct ssl_stream, stream);
  }
  
  static int
  ssl_open(const char *name, char *suffix, struct stream **streamp, uint8_t dscp)
  {
      int error, fd;
  
      error = ssl_init();
      if (error) {
          return error;
      }
  
      error = inet_open_active(SOCK_STREAM, suffix, OFP_OLD_PORT, NULL, &fd,
                               dscp);
      if (fd >= 0) {
          int state = error ? STATE_TCP_CONNECTING : STATE_SSL_CONNECTING;
          return new_ssl_stream(name, fd, CLIENT, state, streamp);
      } else {
          VLOG_ERR("%s: connect: %s", name, ovs_strerror(error));
          return error;
      }
  }
  
  static int
  do_ca_cert_bootstrap(struct stream *stream)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
      STACK_OF(X509) *chain;
      X509 *cert;
      FILE *file;
      int error;
      int fd;
  
      chain = SSL_get_peer_cert_chain(sslv->ssl);
      if (!chain || !sk_X509_num(chain)) {
          VLOG_ERR("could not bootstrap CA cert: no certificate presented by "
                   "peer");
          return EPROTO;
      }
      cert = sk_X509_value(chain, sk_X509_num(chain) - 1);
  
      /* Check that 'cert' is self-signed.  Otherwise it is not a CA
       * certificate and we should not attempt to use it as one. */
      error = X509_check_issued(cert, cert);
      if (error) {
          VLOG_ERR("could not bootstrap CA cert: obtained certificate is "
                   "not self-signed (%s)",
                   X509_verify_cert_error_string(error));
          if (sk_X509_num(chain) < 2) {
              VLOG_ERR("only one certificate was received, so probably the peer "
                       "is not configured to send its CA certificate");
          }
          return EPROTO;
      }
  
      fd = open(ca_cert.file_name, O_CREAT | O_EXCL | O_WRONLY, 0444);
      if (fd < 0) {
          if (errno == EEXIST) {
              VLOG_INFO_RL(&rl, "reading CA cert %s created by another process",
                           ca_cert.file_name);
              stream_ssl_set_ca_cert_file__(ca_cert.file_name, true, true);
              return EPROTO;
          } else {
              VLOG_ERR("could not bootstrap CA cert: creating %s failed: %s",
                       ca_cert.file_name, ovs_strerror(errno));
              return errno;
          }
      }
  
      file = fdopen(fd, "w");
      if (!file) {
          error = errno;
          VLOG_ERR("could not bootstrap CA cert: fdopen failed: %s",
                   ovs_strerror(error));
          unlink(ca_cert.file_name);
          return error;
      }
  
      if (!PEM_write_X509(file, cert)) {
          VLOG_ERR("could not bootstrap CA cert: PEM_write_X509 to %s failed: "
                   "%s", ca_cert.file_name,
                   ERR_error_string(ERR_get_error(), NULL));
          fclose(file);
          unlink(ca_cert.file_name);
          return EIO;
      }
  
      if (fclose(file)) {
          error = errno;
          VLOG_ERR("could not bootstrap CA cert: writing %s failed: %s",
                   ca_cert.file_name, ovs_strerror(error));
          unlink(ca_cert.file_name);
          return error;
      }
  
      VLOG_INFO("successfully bootstrapped CA cert to %s", ca_cert.file_name);
      log_ca_cert(ca_cert.file_name, cert);
      bootstrap_ca_cert = false;
      ca_cert.read = true;
  
      /* SSL_CTX_add_client_CA makes a copy of cert's relevant data. */
      SSL_CTX_add_client_CA(ctx, cert);
  
      /* SSL_CTX_use_certificate() takes ownership of the certificate passed in.
       * 'cert' is owned by sslv->ssl, so we need to duplicate it. */
      cert = X509_dup(cert);
      if (!cert) {
          out_of_memory();
      }
      SSL_CTX_set_cert_store(ctx, X509_STORE_new());
      if (SSL_CTX_load_verify_locations(ctx, ca_cert.file_name, NULL) != 1) {
          VLOG_ERR("SSL_CTX_load_verify_locations: %s",
                   ERR_error_string(ERR_get_error(), NULL));
          return EPROTO;
      }
      VLOG_INFO("killing successful connection to retry using CA cert");
      return EPROTO;
  }
  
  static int
  ssl_connect(struct stream *stream)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
      int retval;
  
      switch (sslv->state) {
      case STATE_TCP_CONNECTING:
          retval = check_connection_completion(sslv->fd);
          if (retval) {
              return retval;
          }
          sslv->state = STATE_SSL_CONNECTING;
          setsockopt_tcp_nodelay(sslv->fd);
          /* Fall through. */
  
      case STATE_SSL_CONNECTING:
          /* Capture the first few bytes of received data so that we can guess
           * what kind of funny data we've been sent if SSL negotiation fails. */
          if (sslv->n_head <= 0) {
              sslv->n_head = recv(sslv->fd, sslv->head, sizeof sslv->head,
                                  MSG_PEEK);
          }
  
          retval = (sslv->type == CLIENT
                     ? SSL_connect(sslv->ssl) : SSL_accept(sslv->ssl));
          if (retval != 1) {
              int error = SSL_get_error(sslv->ssl, retval);
              if (retval < 0 && ssl_wants_io(error)) {
                  return EAGAIN;
              } else {
                  int unused;
  
                  interpret_ssl_error((sslv->type == CLIENT ? "SSL_connect"
                                       : "SSL_accept"), retval, error, &unused);
                  shutdown(sslv->fd, SHUT_RDWR);
                  stream_report_content(sslv->head, sslv->n_head, STREAM_SSL,
                                        THIS_MODULE, stream_get_name(stream));
                  return EPROTO;
              }
          } else if (bootstrap_ca_cert) {
              return do_ca_cert_bootstrap(stream);
          } else if (verify_peer_cert
                     && ((SSL_get_verify_mode(sslv->ssl)
                         & (SSL_VERIFY_NONE | SSL_VERIFY_PEER))
                         != SSL_VERIFY_PEER)) {
              /* Two or more SSL connections completed at the same time while we
               * were in bootstrap mode.  Only one of these can finish the
               * bootstrap successfully.  The other one(s) must be rejected
               * because they were not verified against the bootstrapped CA
               * certificate.  (Alternatively we could verify them against the CA
               * certificate, but that's more trouble than it's worth.  These
               * connections will succeed the next time they retry, assuming that
               * they have a certificate against the correct CA.) */
              VLOG_INFO("rejecting SSL connection during bootstrap race window");
              return EPROTO;
          } else {
              return 0;
          }
      }
  
      OVS_NOT_REACHED();
  }
  
  static void
  ssl_close(struct stream *stream)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
      ssl_clear_txbuf(sslv);
  
      /* Attempt clean shutdown of the SSL connection.  This will work most of
       * the time, as long as the kernel send buffer has some free space and the
       * SSL connection isn't renegotiating, etc.  That has to be good enough,
       * since we don't have any way to continue the close operation in the
       * background. */
      SSL_shutdown(sslv->ssl);
  
      /* SSL_shutdown() might have signaled an error, in which case we need to
       * flush it out of the OpenSSL error queue or the next OpenSSL operation
       * will falsely signal an error. */
      ERR_clear_error();
  
      SSL_free(sslv->ssl);
      closesocket(sslv->fd);
      free(sslv);
  }
  
  static void
  interpret_queued_ssl_error(const char *function)
  {
      int queued_error = ERR_get_error();
      if (queued_error != 0) {
          VLOG_WARN_RL(&rl, "%s: %s",
                       function, ERR_error_string(queued_error, NULL));
      } else {
          VLOG_ERR_RL(&rl, "%s: SSL_ERROR_SSL without queued error", function);
      }
  }
  
  static int
  interpret_ssl_error(const char *function, int ret, int error,
                      int *want)
  {
      *want = SSL_NOTHING;
  
      switch (error) {
      case SSL_ERROR_NONE:
          VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_NONE", function);
          break;
  
      case SSL_ERROR_ZERO_RETURN:
          VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_ZERO_RETURN", function);
          break;
  
      case SSL_ERROR_WANT_READ:
          *want = SSL_READING;
          return EAGAIN;
  
      case SSL_ERROR_WANT_WRITE:
          *want = SSL_WRITING;
          return EAGAIN;
  
      case SSL_ERROR_WANT_CONNECT:
          VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_CONNECT", function);
          break;
  
      case SSL_ERROR_WANT_ACCEPT:
          VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_ACCEPT", function);
          break;
  
      case SSL_ERROR_WANT_X509_LOOKUP:
          VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_X509_LOOKUP",
                      function);
          break;
  
      case SSL_ERROR_SYSCALL: {
          int queued_error = ERR_get_error();
          if (queued_error == 0) {
              if (ret < 0) {
                  int status = errno;
                  VLOG_WARN_RL(&rl, "%s: system error (%s)",
                               function, ovs_strerror(status));
                  return status;
              } else {
                  VLOG_WARN_RL(&rl, "%s: unexpected SSL connection close",
                               function);
                  return EPROTO;
              }
          } else {
              VLOG_WARN_RL(&rl, "%s: %s",
                           function, ERR_error_string(queued_error, NULL));
              break;
          }
      }
  
      case SSL_ERROR_SSL:
          interpret_queued_ssl_error(function);
          break;
  
      default:
          VLOG_ERR_RL(&rl, "%s: bad SSL error code %d", function, error);
          break;
      }
      return EIO;
  }
  
  static ssize_t
  ssl_recv(struct stream *stream, void *buffer, size_t n)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
      int old_state;
      ssize_t ret;
  
      /* Behavior of zero-byte SSL_read is poorly defined. */
      ovs_assert(n > 0);
  
      old_state = SSL_get_state(sslv->ssl);
      ret = SSL_read(sslv->ssl, buffer, n);
      if (old_state != SSL_get_state(sslv->ssl)) {
          sslv->tx_want = SSL_NOTHING;
      }
      sslv->rx_want = SSL_NOTHING;
  
      if (ret > 0) {
          return ret;
      } else {
          int error = SSL_get_error(sslv->ssl, ret);
          if (error == SSL_ERROR_ZERO_RETURN) {
              return 0;
          } else {
              return -interpret_ssl_error("SSL_read", ret, error,
                                          &sslv->rx_want);
          }
      }
  }
  
  static void
  ssl_clear_txbuf(struct ssl_stream *sslv)
  {
      ofpbuf_delete(sslv->txbuf);
      sslv->txbuf = NULL;
  }
  
  static int
  ssl_do_tx(struct stream *stream)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
  
      for (;;) {
          int old_state = SSL_get_state(sslv->ssl);
          int ret = SSL_write(sslv->ssl,
                              ofpbuf_data(sslv->txbuf), ofpbuf_size(sslv->txbuf));
          if (old_state != SSL_get_state(sslv->ssl)) {
              sslv->rx_want = SSL_NOTHING;
          }
          sslv->tx_want = SSL_NOTHING;
          if (ret > 0) {
              ofpbuf_pull(sslv->txbuf, ret);
              if (ofpbuf_size(sslv->txbuf) == 0) {
                  return 0;
              }
          } else {
              int ssl_error = SSL_get_error(sslv->ssl, ret);
              if (ssl_error == SSL_ERROR_ZERO_RETURN) {
                  VLOG_WARN_RL(&rl, "SSL_write: connection closed");
                  return EPIPE;
              } else {
                  return interpret_ssl_error("SSL_write", ret, ssl_error,
                                             &sslv->tx_want);
              }
          }
      }
  }
  
  static ssize_t
  ssl_send(struct stream *stream, const void *buffer, size_t n)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
  
      if (sslv->txbuf) {
          return -EAGAIN;
      } else {
          int error;
  
          sslv->txbuf = ofpbuf_clone_data(buffer, n);
          error = ssl_do_tx(stream);
          switch (error) {
          case 0:
              ssl_clear_txbuf(sslv);
              return n;
          case EAGAIN:
              return n;
          default:
              sslv->txbuf = NULL;
              return -error;
          }
      }
  }
  
  static void
  ssl_run(struct stream *stream)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
  
      if (sslv->txbuf && ssl_do_tx(stream) != EAGAIN) {
          ssl_clear_txbuf(sslv);
      }
  }
  
  static void
  ssl_run_wait(struct stream *stream)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
  
      if (sslv->tx_want != SSL_NOTHING) {
          poll_fd_wait(sslv->fd, want_to_poll_events(sslv->tx_want));
      }
  }
  
  static void
  ssl_wait(struct stream *stream, enum stream_wait_type wait)
  {
      struct ssl_stream *sslv = ssl_stream_cast(stream);
  
      switch (wait) {
      case STREAM_CONNECT:
          if (stream_connect(stream) != EAGAIN) {
              poll_immediate_wake();
          } else {
              switch (sslv->state) {
              case STATE_TCP_CONNECTING:
                  poll_fd_wait(sslv->fd, POLLOUT);
                  break;
  
              case STATE_SSL_CONNECTING:
                  /* ssl_connect() called SSL_accept() or SSL_connect(), which
                   * set up the status that we test here. */
                  poll_fd_wait(sslv->fd,
                                 want_to_poll_events(SSL_want(sslv->ssl)));
                  break;
  
              default:
                  OVS_NOT_REACHED();
              }
          }
          break;
  
      case STREAM_RECV:
          if (sslv->rx_want != SSL_NOTHING) {
              poll_fd_wait(sslv->fd, want_to_poll_events(sslv->rx_want));
          } else {
              poll_immediate_wake();
          }
          break;
  
      case STREAM_SEND:
          if (!sslv->txbuf) {
              /* We have room in our tx queue. */
              poll_immediate_wake();
          } else {
              /* stream_run_wait() will do the right thing; don't bother with
               * redundancy. */
          }
          break;
  
      default:
          OVS_NOT_REACHED();
      }
  }
  
  const struct stream_class ssl_stream_class = {
      "ssl",                      /* name */
      true,                       /* needs_probes */
      ssl_open,                   /* open */
      ssl_close,                  /* close */
      ssl_connect,                /* connect */
      ssl_recv,                   /* recv */
      ssl_send,                   /* send */
      ssl_run,                    /* run */
      ssl_run_wait,               /* run_wait */
      ssl_wait,                   /* wait */
  };
  
  /* Passive SSL. */
  
  struct pssl_pstream
  {
      struct pstream pstream;
      int fd;
  };
  
  const struct pstream_class pssl_pstream_class;
  
  static struct pssl_pstream *
  pssl_pstream_cast(struct pstream *pstream)
  {
      pstream_assert_class(pstream, &pssl_pstream_class);
      return CONTAINER_OF(pstream, struct pssl_pstream, pstream);
  }
  
  static int
  pssl_open(const char *name OVS_UNUSED, char *suffix, struct pstream **pstreamp,
            uint8_t dscp)
  {
      char bound_name[SS_NTOP_BUFSIZE + 16];
      char addrbuf[SS_NTOP_BUFSIZE];
      struct sockaddr_storage ss;
      struct pssl_pstream *pssl;
      uint16_t port;
      int retval;
      int fd;
  
      retval = ssl_init();
      if (retval) {
          return retval;
      }
  
      fd = inet_open_passive(SOCK_STREAM, suffix, OFP_OLD_PORT, &ss, dscp, true);
      if (fd < 0) {
          return -fd;
      }
  
      port = ss_get_port(&ss);
      snprintf(bound_name, sizeof bound_name, "ptcp:%"PRIu16":%s",
               port, ss_format_address(&ss, addrbuf, sizeof addrbuf));
  
      pssl = xmalloc(sizeof *pssl);
      pstream_init(&pssl->pstream, &pssl_pstream_class, bound_name);
      pstream_set_bound_port(&pssl->pstream, htons(port));
      pssl->fd = fd;
      *pstreamp = &pssl->pstream;
      return 0;
  }
  
  static void
  pssl_close(struct pstream *pstream)
  {
      struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
      closesocket(pssl->fd);
      free(pssl);
  }
  
  static int
  pssl_accept(struct pstream *pstream, struct stream **new_streamp)
  {
      struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
      char name[SS_NTOP_BUFSIZE + 16];
      char addrbuf[SS_NTOP_BUFSIZE];
      struct sockaddr_storage ss;
      socklen_t ss_len = sizeof ss;
      int new_fd;
      int error;
  
      new_fd = accept(pssl->fd, (struct sockaddr *) &ss, &ss_len);
      if (new_fd < 0) {
          error = sock_errno();
  #ifdef _WIN32
          if (error == WSAEWOULDBLOCK) {
              error = EAGAIN;
          }
  #endif
          if (error != EAGAIN) {
              VLOG_DBG_RL(&rl, "accept: %s", sock_strerror(error));
          }
          return error;
      }
  
      error = set_nonblocking(new_fd);
      if (error) {
          closesocket(new_fd);
          return error;
      }
  
      snprintf(name, sizeof name, "tcp:%s:%"PRIu16,
               ss_format_address(&ss, addrbuf, sizeof addrbuf),
               ss_get_port(&ss));
      return new_ssl_stream(name, new_fd, SERVER, STATE_SSL_CONNECTING,
                            new_streamp);
  }
  
  static void
  pssl_wait(struct pstream *pstream)
  {
      struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
      poll_fd_wait(pssl->fd, POLLIN);
  }
  
  static int
  pssl_set_dscp(struct pstream *pstream, uint8_t dscp)
  {
      struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
      return set_dscp(pssl->fd, dscp);
  }
  
  const struct pstream_class pssl_pstream_class = {
      "pssl",
      true,
      pssl_open,
      pssl_close,
      pssl_accept,
      pssl_wait,
      pssl_set_dscp,
  };
  
  /*
   * Returns true if OpenSSL error is WANT_READ or WANT_WRITE, indicating that
   * OpenSSL is requesting that we call it back when the socket is ready for read
   * or writing, respectively.
   */
  static bool
  ssl_wants_io(int ssl_error)
  {
      return (ssl_error == SSL_ERROR_WANT_WRITE
              || ssl_error == SSL_ERROR_WANT_READ);
  }
  
  static int
  ssl_init(void)
  {
      static int init_status = -1;
      if (init_status < 0) {
          init_status = do_ssl_init();
          ovs_assert(init_status >= 0);
      }
      return init_status;
  }
  
  static int
  do_ssl_init(void)
  {
      SSL_METHOD *method;
  
  #ifdef _WIN32
      /* The following call is needed if we "#include <openssl/applink.c>". */
      CRYPTO_malloc_init();
  #endif
      SSL_library_init();
      SSL_load_error_strings();
  
      if (!RAND_status()) {
          /* We occasionally see OpenSSL fail to seed its random number generator
           * in heavily loaded hypervisors.  I suspect the following scenario:
           *
           * 1. OpenSSL calls read() to get 32 bytes from /dev/urandom.
           * 2. The kernel generates 10 bytes of randomness and copies it out.
           * 3. A signal arrives (perhaps SIGALRM).
           * 4. The kernel interrupts the system call to service the signal.
           * 5. Userspace gets 10 bytes of entropy.
           * 6. OpenSSL doesn't read again to get the final 22 bytes.  Therefore
           *    OpenSSL doesn't have enough entropy to consider itself
           *    initialized.
           *
           * The only part I'm not entirely sure about is #6, because the OpenSSL
           * code is so hard to read. */
          uint8_t seed[32];
          int retval;
  
          VLOG_WARN("OpenSSL random seeding failed, reseeding ourselves");
  
          retval = get_entropy(seed, sizeof seed);
          if (retval) {
              VLOG_ERR("failed to obtain entropy (%s)",
                       ovs_retval_to_string(retval));
              return retval > 0 ? retval : ENOPROTOOPT;
          }
  
          RAND_seed(seed, sizeof seed);
      }
  
      /* OpenSSL has a bunch of "connection methods": SSLv2_method(),
       * SSLv3_method(), TLSv1_method(), SSLv23_method(), ...  Most of these
       * support exactly one version of SSL, e.g. TLSv1_method() supports TLSv1
       * only, not any earlier *or later* version.  The only exception is
       * SSLv23_method(), which in fact supports *any* version of SSL and TLS.
       * We don't want SSLv2 or SSLv3 support, so we turn it off below with
       * SSL_CTX_set_options().
       *
       * The cast is needed to avoid a warning with newer versions of OpenSSL in
       * which SSLv23_method() returns a "const" pointer. */
      method = CONST_CAST(SSL_METHOD *, SSLv23_method());
      if (method == NULL) {
          VLOG_ERR("TLSv1_method: %s", ERR_error_string(ERR_get_error(), NULL));
          return ENOPROTOOPT;
      }
  
      ctx = SSL_CTX_new(method);
      if (ctx == NULL) {
          VLOG_ERR("SSL_CTX_new: %s", ERR_error_string(ERR_get_error(), NULL));
          return ENOPROTOOPT;
      }
      SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
      SSL_CTX_set_tmp_dh_callback(ctx, tmp_dh_callback);
      SSL_CTX_set_mode(ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
      SSL_CTX_set_mode(ctx, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
      SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
                         NULL);
  
      return 0;
  }
  
  static DH *
  tmp_dh_callback(SSL *ssl OVS_UNUSED, int is_export OVS_UNUSED, int keylength)
  {
      struct dh {
          int keylength;
          DH *dh;
          DH *(*constructor)(void);
      };
  
      static struct dh dh_table[] = {
          {1024, NULL, get_dh1024},
          {2048, NULL, get_dh2048},
          {4096, NULL, get_dh4096},
      };
  
      struct dh *dh;
  
      for (dh = dh_table; dh < &dh_table[ARRAY_SIZE(dh_table)]; dh++) {
          if (dh->keylength == keylength) {
              if (!dh->dh) {
                  dh->dh = dh->constructor();
                  if (!dh->dh) {
                      out_of_memory();
                  }
              }
              return dh->dh;
          }
      }
      VLOG_ERR_RL(&rl, "no Diffie-Hellman parameters for key length %d",
                  keylength);
      return NULL;
  }
  
  /* Returns true if SSL is at least partially configured. */
  bool
  stream_ssl_is_configured(void)
  {
      return private_key.file_name || certificate.file_name || ca_cert.file_name;
  }
  
  static bool
  update_ssl_config(struct ssl_config_file *config, const char *file_name)
  {
      struct timespec mtime;
      int error;
  
      if (ssl_init() || !file_name) {
          return false;
      }
  
      /* If the file name hasn't changed and neither has the file contents, stop
       * here. */
      error = get_mtime(file_name, &mtime);
      if (error && error != ENOENT) {
          VLOG_ERR_RL(&rl, "%s: stat failed (%s)",
                      file_name, ovs_strerror(error));
      }
      if (config->file_name
          && !strcmp(config->file_name, file_name)
          && mtime.tv_sec == config->mtime.tv_sec
          && mtime.tv_nsec == config->mtime.tv_nsec) {
          return false;
      }
  
      /* Update 'config'. */
      config->mtime = mtime;
      if (file_name != config->file_name) {
          free(config->file_name);
          config->file_name = xstrdup(file_name);
      }
      return true;
  }
  
  static void
  stream_ssl_set_private_key_file__(const char *file_name)
  {
      if (SSL_CTX_use_PrivateKey_file(ctx, file_name, SSL_FILETYPE_PEM) == 1) {
          private_key.read = true;
      } else {
          VLOG_ERR("SSL_use_PrivateKey_file: %s",
                   ERR_error_string(ERR_get_error(), NULL));
      }
  }
  
  void
  stream_ssl_set_private_key_file(const char *file_name)
  {
      if (update_ssl_config(&private_key, file_name)) {
          stream_ssl_set_private_key_file__(file_name);
      }
  }
  
  static void
  stream_ssl_set_certificate_file__(const char *file_name)
  {
      if (SSL_CTX_use_certificate_chain_file(ctx, file_name) == 1) {
          certificate.read = true;
      } else {
          VLOG_ERR("SSL_use_certificate_file: %s",
                   ERR_error_string(ERR_get_error(), NULL));
      }
  }
  
  void
  stream_ssl_set_certificate_file(const char *file_name)
  {
      if (update_ssl_config(&certificate, file_name)) {
          stream_ssl_set_certificate_file__(file_name);
      }
  }
  
  /* Sets the private key and certificate files in one operation.  Use this
   * interface, instead of calling stream_ssl_set_private_key_file() and
   * stream_ssl_set_certificate_file() individually, in the main loop of a
   * long-running program whose key and certificate might change at runtime.
   *
   * This is important because of OpenSSL's behavior.  If an OpenSSL context
   * already has a certificate, and stream_ssl_set_private_key_file() is called
   * to install a new private key, OpenSSL will report an error because the new
   * private key does not match the old certificate.  The other order, of setting
   * a new certificate, then setting a new private key, does work.
   *
   * If this were the only problem, calling stream_ssl_set_certificate_file()
   * before stream_ssl_set_private_key_file() would fix it.  But, if the private
   * key is changed before the certificate (e.g. someone "scp"s or "mv"s the new
   * private key in place before the certificate), then OpenSSL would reject that
   * change, and then the change of certificate would succeed, but there would be
   * no associated private key (because it had only changed once and therefore
   * there was no point in re-reading it).
   *
   * This function avoids both problems by, whenever either the certificate or
   * the private key file changes, re-reading both of them, in the correct order.
   */
  void
  stream_ssl_set_key_and_cert(const char *private_key_file,
                              const char *certificate_file)
  {
      if (update_ssl_config(&private_key, private_key_file)
          || update_ssl_config(&certificate, certificate_file)) {
          stream_ssl_set_certificate_file__(certificate_file);
          stream_ssl_set_private_key_file__(private_key_file);
      }
  }
  
  /* Reads the X509 certificate or certificates in file 'file_name'.  On success,
   * stores the address of the first element in an array of pointers to
   * certificates in '*certs' and the number of certificates in the array in
   * '*n_certs', and returns 0.  On failure, stores a null pointer in '*certs', 0
   * in '*n_certs', and returns a positive errno value.
   *
   * The caller is responsible for freeing '*certs'. */
  static int
  read_cert_file(const char *file_name, X509 ***certs, size_t *n_certs)
  {
      FILE *file;
      size_t allocated_certs = 0;
  
      *certs = NULL;
      *n_certs = 0;
  
      file = fopen(file_name, "r");
      if (!file) {
          VLOG_ERR("failed to open %s for reading: %s",
                   file_name, ovs_strerror(errno));
          return errno;
      }
  
      for (;;) {
          X509 *certificate;
          int c;
  
          /* Read certificate from file. */
          certificate = PEM_read_X509(file, NULL, NULL, NULL);
          if (!certificate) {
              size_t i;
  
              VLOG_ERR("PEM_read_X509 failed reading %s: %s",
                       file_name, ERR_error_string(ERR_get_error(), NULL));
              for (i = 0; i < *n_certs; i++) {
                  X509_free((*certs)[i]);
              }
              free(*certs);
              *certs = NULL;
              *n_certs = 0;
              fclose(file);
              return EIO;
          }
  
          /* Add certificate to array. */
          if (*n_certs >= allocated_certs) {
              *certs = x2nrealloc(*certs, &allocated_certs, sizeof **certs);
          }
          (*certs)[(*n_certs)++] = certificate;
  
          /* Are there additional certificates in the file? */
          do {
              c = getc(file);
          } while (isspace(c));
          if (c == EOF) {
              break;
          }
          ungetc(c, file);
      }
      fclose(file);
      return 0;
  }
  
  
  /* Sets 'file_name' as the name of a file containing one or more X509
   * certificates to send to the peer.  Typical use in OpenFlow is to send the CA
   * certificate to the peer, which enables a switch to pick up the controller's
   * CA certificate on its first connection. */
  void
  stream_ssl_set_peer_ca_cert_file(const char *file_name)
  {
      X509 **certs;
      size_t n_certs;
      size_t i;
  
      if (ssl_init()) {
          return;
      }
  
      if (!read_cert_file(file_name, &certs, &n_certs)) {
          for (i = 0; i < n_certs; i++) {
              if (SSL_CTX_add_extra_chain_cert(ctx, certs[i]) != 1) {
                  VLOG_ERR("SSL_CTX_add_extra_chain_cert: %s",
                           ERR_error_string(ERR_get_error(), NULL));
              }
          }
          free(certs);
      }
  }
  
  /* Logs fingerprint of CA certificate 'cert' obtained from 'file_name'. */
  static void
  log_ca_cert(const char *file_name, X509 *cert)
  {
      unsigned char digest[EVP_MAX_MD_SIZE];
      unsigned int n_bytes;
      struct ds fp;
      char *subject;
  
      ds_init(&fp);
      if (!X509_digest(cert, EVP_sha1(), digest, &n_bytes)) {
          ds_put_cstr(&fp, "<out of memory>");
      } else {
          unsigned int i;
          for (i = 0; i < n_bytes; i++) {
              if (i) {
                  ds_put_char(&fp, ':');
              }
              ds_put_format(&fp, "%02x", digest[i]);
          }
      }
      subject = X509_NAME_oneline(X509_get_subject_name(cert), NULL, 0);
      VLOG_INFO("Trusting CA cert from %s (%s) (fingerprint %s)", file_name,
                subject ? subject : "<out of memory>", ds_cstr(&fp));
      OPENSSL_free(subject);
      ds_destroy(&fp);
  }
  
  static void
  stream_ssl_set_ca_cert_file__(const char *file_name,
                                bool bootstrap, bool force)
  {
      X509 **certs;
      size_t n_certs;
      struct stat s;
  
      if (!update_ssl_config(&ca_cert, file_name) && !force) {
          return;
      }
  
      if (!strcmp(file_name, "none")) {
          verify_peer_cert = false;
          VLOG_WARN("Peer certificate validation disabled "
                    "(this is a security risk)");
      } else if (bootstrap && stat(file_name, &s) && errno == ENOENT) {
          bootstrap_ca_cert = true;
      } else if (!read_cert_file(file_name, &certs, &n_certs)) {
          size_t i;
  
          /* Set up list of CAs that the server will accept from the client. */
          for (i = 0; i < n_certs; i++) {
              /* SSL_CTX_add_client_CA makes a copy of the relevant data. */
              if (SSL_CTX_add_client_CA(ctx, certs[i]) != 1) {
                  VLOG_ERR("failed to add client certificate %"PRIuSIZE" from %s: %s",
                           i, file_name,
                           ERR_error_string(ERR_get_error(), NULL));
              } else {
                  log_ca_cert(file_name, certs[i]);
              }
              X509_free(certs[i]);
          }
          free(certs);
  
          /* Set up CAs for OpenSSL to trust in verifying the peer's
           * certificate. */
          SSL_CTX_set_cert_store(ctx, X509_STORE_new());
          if (SSL_CTX_load_verify_locations(ctx, file_name, NULL) != 1) {
              VLOG_ERR("SSL_CTX_load_verify_locations: %s",
                       ERR_error_string(ERR_get_error(), NULL));
              return;
          }
  
          bootstrap_ca_cert = false;
      }
      ca_cert.read = true;
  }
  
  /* Sets 'file_name' as the name of the file from which to read the CA
   * certificate used to verify the peer within SSL connections.  If 'bootstrap'
   * is false, the file must exist.  If 'bootstrap' is false, then the file is
   * read if it is exists; if it does not, then it will be created from the CA
   * certificate received from the peer on the first SSL connection. */
  void
  stream_ssl_set_ca_cert_file(const char *file_name, bool bootstrap)
  {
      stream_ssl_set_ca_cert_file__(file_name, bootstrap, false);
  }
  
  /* SSL protocol logging. */
  
  static const char *
  ssl_alert_level_to_string(uint8_t type)
  {
      switch (type) {
      case 1: return "warning";
      case 2: return "fatal";
      default: return "<unknown>";
      }
  }
  
  static const char *
  ssl_alert_description_to_string(uint8_t type)
  {
      switch (type) {
      case 0: return "close_notify";
      case 10: return "unexpected_message";
      case 20: return "bad_record_mac";
      case 21: return "decryption_failed";
      case 22: return "record_overflow";
      case 30: return "decompression_failure";
      case 40: return "handshake_failure";
      case 42: return "bad_certificate";
      case 43: return "unsupported_certificate";
      case 44: return "certificate_revoked";
      case 45: return "certificate_expired";
      case 46: return "certificate_unknown";
      case 47: return "illegal_parameter";
      case 48: return "unknown_ca";
      case 49: return "access_denied";
      case 50: return "decode_error";
      case 51: return "decrypt_error";
      case 60: return "export_restriction";
      case 70: return "protocol_version";
      case 71: return "insufficient_security";
      case 80: return "internal_error";
      case 90: return "user_canceled";
      case 100: return "no_renegotiation";
      default: return "<unknown>";
      }
  }
  
  static const char *
  ssl_handshake_type_to_string(uint8_t type)
  {
      switch (type) {
      case 0: return "hello_request";
      case 1: return "client_hello";
      case 2: return "server_hello";
      case 11: return "certificate";
      case 12: return "server_key_exchange";
      case 13: return "certificate_request";
      case 14: return "server_hello_done";
      case 15: return "certificate_verify";
      case 16: return "client_key_exchange";
      case 20: return "finished";
      default: return "<unknown>";
      }
  }
  
  static void
  ssl_protocol_cb(int write_p, int version OVS_UNUSED, int content_type,
                  const void *buf_, size_t len, SSL *ssl OVS_UNUSED, void *sslv_)
  {
      const struct ssl_stream *sslv = sslv_;
      const uint8_t *buf = buf_;
      struct ds details;
  
      if (!VLOG_IS_DBG_ENABLED()) {
          return;
      }
  
      ds_init(&details);
      if (content_type == 20) {
          ds_put_cstr(&details, "change_cipher_spec");
      } else if (content_type == 21) {
          ds_put_format(&details, "alert: %s, %s",
                        ssl_alert_level_to_string(buf[0]),
                        ssl_alert_description_to_string(buf[1]));
      } else if (content_type == 22) {
          ds_put_format(&details, "handshake: %s",
                        ssl_handshake_type_to_string(buf[0]));
      } else {
          ds_put_format(&details, "type %d", content_type);
      }
  
      VLOG_DBG("%s%u%s%s %s (%"PRIuSIZE" bytes)",
               sslv->type == CLIENT ? "client" : "server",
               sslv->session_nr, write_p ? "-->" : "<--",
               stream_get_name(&sslv->stream), ds_cstr(&details), len);
  
      ds_destroy(&details);
  }
  