connection.c

关于tor匿名通信的源代码

  tor_assert(0);
};
#endif /* HAVE_SYS_UN_H */

/** 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.
 */
static connection_t *
connection_create_listener(struct sockaddr *listensockaddr, int type,
                           char* address)
{
  /*XXXX021 this function should take a socklen too. */
  connection_t *conn;
  int s; /* the socket we're going to make */
  uint16_t usePort = 0;
  int start_reading = 0;

  if (get_n_open_sockets() >= get_options()->_ConnLimit-1) {
    int n_conns = get_n_open_sockets();
    log_warn(LD_NET,"Failing because we have %d connections already. Please "
             "raise your ulimit -n.", n_conns);
    control_event_general_status(LOG_WARN, "TOO_MANY_CONNECTIONS CURRENT=%d",
                                 n_conns);
    return NULL;
  }

  if (listensockaddr->sa_family == AF_INET) {
    int is_tcp = (type != CONN_TYPE_AP_DNS_LISTENER);
#ifndef MS_WINDOWS
    int one=1;
#endif
    if (is_tcp)
      start_reading = 1;

    usePort = ntohs( (uint16_t)
                     ((struct sockaddr_in *)listensockaddr)->sin_port);

    log_notice(LD_NET, "Opening %s on %s:%d",
               conn_type_to_string(type), address, usePort);

    s = tor_open_socket(PF_INET,
                        is_tcp ? SOCK_STREAM : SOCK_DGRAM,
                        is_tcp ? IPPROTO_TCP: IPPROTO_UDP);
    if (s < 0) {
      log_warn(LD_NET,"Socket creation failed.");
      goto err;
    }

#ifndef MS_WINDOWS
    /* 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. */
    setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (void*) &one,
               (socklen_t)sizeof(one));
#endif

    if (bind(s,listensockaddr,(socklen_t)sizeof(struct sockaddr_in)) < 0) {
      const char *helpfulhint = "";
      int e = tor_socket_errno(s);
      if (ERRNO_IS_EADDRINUSE(e))
        helpfulhint = ". Is Tor already running?";
      log_warn(LD_NET, "Could not bind to %s:%u: %s%s", address, usePort,
               tor_socket_strerror(e), helpfulhint);
      tor_close_socket(s);
      goto err;
    }

    if (is_tcp) {
      if (listen(s,SOMAXCONN) < 0) {
        log_warn(LD_NET, "Could not listen on %s:%u: %s", address, usePort,
                 tor_socket_strerror(tor_socket_errno(s)));
        tor_close_socket(s);
        goto err;
      }
    }
#ifdef HAVE_SYS_UN_H
  } else if (listensockaddr->sa_family == AF_UNIX) {
    start_reading = 1;

    /* For now only control ports can be unix domain sockets
     * and listeners at the same time */
    tor_assert(type == CONN_TYPE_CONTROL_LISTENER);

    log_notice(LD_NET, "Opening %s on %s",
               conn_type_to_string(type), address);

    if (unlink(address) < 0 && errno != ENOENT) {
      log_warn(LD_NET, "Could not unlink %s: %s", address,
                       strerror(errno));
      goto err;
    }
    s = tor_open_socket(AF_UNIX, SOCK_STREAM, 0);
    if (s < 0) {
      log_warn(LD_NET,"Socket creation failed: %s.", strerror(errno));
      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;
    }

    if (listen(s,SOMAXCONN) < 0) {
      log_warn(LD_NET, "Could not listen on %s: %s", address,
               tor_socket_strerror(tor_socket_errno(s)));
      tor_close_socket(s);
      goto err;
    }
#endif /* HAVE_SYS_UN_H */
  } else {
      log_err(LD_BUG,"Got unexpected address family %d.",
              listensockaddr->sa_family);
      tor_assert(0);
  }

  set_socket_nonblocking(s);

  conn = connection_new(type, listensockaddr->sa_family);
  conn->socket_family = listensockaddr->sa_family;
  conn->s = s;
  conn->address = tor_strdup(address);
  conn->port = usePort;

  if (connection_add(conn) < 0) { /* no space, forget it */
    log_warn(LD_NET,"connection_add for listener failed. Giving up.");
    connection_free(conn);
    goto err;
  }

  log_debug(LD_NET,"%s listening on port %u.",
            conn_type_to_string(type), usePort);

  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);
  }

  return conn;

 err:
  return NULL;
}

/** Do basic sanity checking on a newly received socket. Return 0
 * if it looks ok, else return -1. */
static int
check_sockaddr_in(struct sockaddr *sa, int len, int level)
{
  int ok = 1;
  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 (sa->sa_family != AF_INET) {
    log_fn(level, LD_NET, "Family of address not as expected: %d vs %d",
           sa->sa_family, AF_INET);
    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;
  }
  return ok ? 0 : -1;
}

/** 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)
{
  int news; /* the new socket */
  connection_t *newconn;
  /* information about the remote peer when connecting to other routers */
  struct sockaddr_in remote;
  char addrbuf[256];
  /* length of the remote address. Must be whatever accept() needs. */
  socklen_t remotelen = (socklen_t)sizeof(addrbuf);
  char tmpbuf[INET_NTOA_BUF_LEN];
  or_options_t *options = get_options();

  tor_assert((size_t)remotelen >= sizeof(struct sockaddr_in));
  memset(addrbuf, 0, sizeof(addrbuf));

  news = tor_accept_socket(conn->s,(struct sockaddr *)&addrbuf,&remotelen);
  if (news < 0) { /* accept() error */
    int e = tor_socket_errno(conn->s);
    if (ERRNO_IS_ACCEPT_EAGAIN(e)) {
      return 0; /* he hung up before we could accept(). that's fine. */
    } else if (ERRNO_IS_ACCEPT_RESOURCE_LIMIT(e)) {
      log_notice(LD_NET,"accept failed: %s. Dropping incoming connection.",
                 tor_socket_strerror(e));
      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);
    return -1;
  }
  log_debug(LD_NET,
            "Connection accepted on socket %d (child of fd %d).",
            news,conn->s);

  set_socket_nonblocking(news);

  if (options->ConstrainedSockets)
    set_constrained_socket_buffers(news, (int)options->ConstrainedSockSize);

  if (((struct sockaddr*)addrbuf)->sa_family != conn->socket_family) {
    /* This is annoying, but can apparently happen on some Darwins. */
    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(conn->type),
             (int)conn->socket_family,
             (int)((struct sockaddr*)addrbuf)->sa_family);
    tor_close_socket(news);
    return 0;
  }

  if (conn->socket_family == AF_INET) {
    if (check_sockaddr_in((struct sockaddr*)addrbuf, remotelen, LOG_INFO)<0) {
      log_info(LD_NET,
               "accept() returned a strange address; trying getsockname().");
      remotelen=256;
      memset(addrbuf, 0, sizeof(addrbuf));
      if (getsockname(news, (struct sockaddr*)addrbuf, &remotelen)<0) {
        int e = tor_socket_errno(news);
        log_warn(LD_NET, "getsockname() for new connection failed: %s",
                 tor_socket_strerror(e));
      } else {
        if (check_sockaddr_in((struct sockaddr*)addrbuf, remotelen,
                              LOG_WARN) < 0) {
          log_warn(LD_NET,"Something's wrong with this conn. Closing it.");
          tor_close_socket(news);
          return 0;
        }
      }
    }
    memcpy(&remote, addrbuf, sizeof(struct sockaddr_in));

    /* 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(ntohl(remote.sin_addr.s_addr)) == 0) {
        tor_inet_ntoa(&remote.sin_addr, tmpbuf, sizeof(tmpbuf));
        log_notice(LD_APP,
                   "Denying socks connection from untrusted address %s.",
                   tmpbuf);
        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(ntohl(remote.sin_addr.s_addr)) == 0) {
        tor_inet_ntoa(&remote.sin_addr, tmpbuf, sizeof(tmpbuf));
        log_notice(LD_DIRSERV,"Denying dir connection from address %s.",
                   tmpbuf);
        tor_close_socket(news);
        return 0;
      }
    }

    newconn = connection_new(new_type, conn->socket_family);
    newconn->s = news;

    /* remember the remote address */
    newconn->addr = ntohl(remote.sin_addr.s_addr);
    newconn->port = ntohs(remote.sin_port);
    newconn->address = tor_dup_addr(newconn->addr);

  } else if (conn->socket_family == AF_UNIX) {
    /* For now only control ports can be unix domain sockets
     * and listeners at the same time */
    tor_assert(conn->type == CONN_TYPE_CONTROL_LISTENER);

    newconn = connection_new(new_type, conn->socket_family);
    newconn->s = news;

    /* remember the remote address -- do we have anything sane to put here? */
    newconn->addr = 0;
    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, conn->type) < 0) {
    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.
 */
static int
connection_init_accepted_conn(connection_t *conn, uint8_t listener_type)
{
  connection_start_reading(conn);

  switch (conn->type) {
    case CONN_TYPE_OR:
      control_event_or_conn_status(TO_OR_CONN(conn), OR_CONN_EVENT_NEW, 0);
      return connection_tls_start_handshake(TO_OR_CONN(conn), 1);
    case CONN_TYPE_AP:
      switch (listener_type) {
        case CONN_TYPE_AP_LISTENER:
          conn->state = AP_CONN_STATE_SOCKS_WAIT;
          break;
        case CONN_TYPE_AP_TRANS_LISTENER:
          conn->state = AP_CONN_STATE_CIRCUIT_WAIT;
          return connection_ap_process_transparent(TO_EDGE_CONN(conn));
        case CONN_TYPE_AP_NATD_LISTENER:
          conn->state = AP_CONN_STATE_NATD_WAIT;
          break;
      }
      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
 * addr:port (they arrive in *host order*). If fail, return -1. Else
 * assign s to conn-\>s: if connected return 1, if EAGAIN return 0.
 *
 * 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,
                   uint32_t addr, uint16_t port)
{
  int s, inprogress = 0;
  struct sockaddr_in dest_addr;
  or_options_t *options = get_options();

  if (get_n_open_sockets() >= get_options()->_ConnLimit-1) {
    int n_conns = get_n_open_sockets();