connection.c

关于tor匿名通信的源代码

    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 -1;
  }

  s = tor_open_socket(PF_INET,SOCK_STREAM,IPPROTO_TCP);
  if (s < 0) {
    log_warn(LD_NET,"Error creating network socket: %s",
             tor_socket_strerror(tor_socket_errno(-1)));
    return -1;
  }

  if (options->OutboundBindAddress) {
    struct sockaddr_in ext_addr;

    memset(&ext_addr, 0, sizeof(ext_addr));
    ext_addr.sin_family = AF_INET;
    ext_addr.sin_port = 0;
    if (!tor_inet_aton(options->OutboundBindAddress, &ext_addr.sin_addr)) {
      log_warn(LD_CONFIG,"Outbound bind address '%s' didn't parse. Ignoring.",
               options->OutboundBindAddress);
    } else {
      if (bind(s, (struct sockaddr*)&ext_addr,
               (socklen_t)sizeof(ext_addr)) < 0) {
        log_warn(LD_NET,"Error binding network socket: %s",
                 tor_socket_strerror(tor_socket_errno(s)));
        tor_close_socket(s);
        return -1;
      }
    }
  }

  set_socket_nonblocking(s);

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

  memset(&dest_addr,0,sizeof(dest_addr));
  dest_addr.sin_family = AF_INET;
  dest_addr.sin_port = htons(port);
  dest_addr.sin_addr.s_addr = htonl(addr);

  log_debug(LD_NET,"Connecting to %s:%u.",escaped_safe_str(address),port);

  if (connect(s,(struct sockaddr *)&dest_addr,
              (socklen_t)sizeof(dest_addr)) < 0) {
    int e = tor_socket_errno(s);
    if (!ERRNO_IS_CONN_EINPROGRESS(e)) {
      /* yuck. kill it. */
      log_info(LD_NET,
               "connect() to %s:%u failed: %s",escaped_safe_str(address),
               port, tor_socket_strerror(e));
      tor_close_socket(s);
      return -1;
    } else {
      inprogress = 1;
    }
  }

  if (!server_mode(options))
    client_check_address_changed(s);

  /* it succeeded. we're connected. */
  log_fn(inprogress?LOG_DEBUG:LOG_INFO, LD_NET,
         "Connection to %s:%u %s (sock %d).",escaped_safe_str(address),
         port, inprogress?"in progress":"established", s);
  conn->s = s;
  if (connection_add(conn) < 0) /* no space, forget it */
    return -1;
  return inprogress ? 0 : 1;
}

/**
 * Launch any configured listener connections of type <b>type</b>.  (A
 * listener is configured if <b>port_option</b> is non-zero.  If any
 * ListenAddress configuration options are given in <b>cfg</b>, create a
 * connection binding to each one.  Otherwise, create a single
 * connection binding to the address <b>default_addr</b>.)
 *
 * Only launch the listeners of this type that are not already open, and
 * only close listeners that are no longer wanted.  Existing listeners
 * that are still configured are not touched.
 *
 * If <b>disable_all_conns</b> is set, then never open new conns, and
 * close the existing ones.
 *
 * Add all old conns that should be closed to <b>replaced_conns</b>.
 * Add all new connections to <b>new_conns</b>.
 */
static int
retry_listeners(int type, config_line_t *cfg,
                int port_option, const char *default_addr,
                smartlist_t *replaced_conns,
                smartlist_t *new_conns,
                int disable_all_conns,
                int socket_family)
{
  smartlist_t *launch = smartlist_create(), *conns;
  int free_launch_elts = 1;
  int r;
  config_line_t *c;
  connection_t *conn;
  config_line_t *line;

  tor_assert(socket_family == AF_INET || socket_family == AF_UNIX);

  if (cfg && port_option) {
    for (c = cfg; c; c = c->next) {
      smartlist_add(launch, c);
    }
    free_launch_elts = 0;
  } else if (port_option) {
    line = tor_malloc_zero(sizeof(config_line_t));
    line->key = tor_strdup("");
    line->value = tor_strdup(default_addr);
    smartlist_add(launch, line);
  }

  /*
  SMARTLIST_FOREACH(launch, config_line_t *, l,
                    log_fn(LOG_NOTICE, "#%s#%s", l->key, l->value));
  */

  conns = get_connection_array();
  SMARTLIST_FOREACH(conns, connection_t *, conn,
  {
    if (conn->type != type ||
        conn->socket_family != socket_family ||
        conn->marked_for_close)
      continue;
    /* Okay, so this is a listener.  Is it configured? */
    line = NULL;
    SMARTLIST_FOREACH(launch, config_line_t *, wanted,
      {
        char *address=NULL;
        uint16_t port;
        switch (socket_family) {
          case AF_INET:
            if (!parse_addr_port(LOG_WARN,
                                 wanted->value, &address, NULL, &port)) {
              int addr_matches = !strcasecmp(address, conn->address);
              tor_free(address);
              if (! port)
                port = port_option;
              if (port == conn->port && addr_matches) {
                line = wanted;
                break;
              }
            }
            break;
          case AF_UNIX:
            if (!strcasecmp(wanted->value, conn->address)) {
              line = wanted;
              break;
            }
            break;
          default:
            tor_assert(0);
        }
      });
    if (!line || disable_all_conns) {
      /* This one isn't configured. Close it. */
      log_notice(LD_NET, "Closing no-longer-configured %s on %s:%d",
                 conn_type_to_string(type), conn->address, conn->port);
      if (replaced_conns) {
        smartlist_add(replaced_conns, conn);
      } else {
        connection_close_immediate(conn);
        connection_mark_for_close(conn);
      }
    } else {
      /* It's configured; we don't need to launch it. */
//      log_debug(LD_NET, "Already have %s on %s:%d",
//                conn_type_to_string(type), conn->address, conn->port);
      smartlist_remove(launch, line);
      if (free_launch_elts)
        config_free_lines(line);
    }
  });

  /* Now open all the listeners that are configured but not opened. */
  r = 0;
  if (!disable_all_conns) {
    SMARTLIST_FOREACH(launch, config_line_t *, cfg_line,
      {
        char *address = NULL;
        struct sockaddr *listensockaddr;

        switch (socket_family) {
          case AF_INET:
            listensockaddr = (struct sockaddr *)
                             create_inet_sockaddr(cfg_line->value,
                                                  (uint16_t) port_option,
                                                  &address);
            break;
          case AF_UNIX:
            listensockaddr = (struct sockaddr *)
                             create_unix_sockaddr(cfg_line->value,
                                                  &address);
            break;
          default:
            tor_assert(0);
        }

        if (listensockaddr) {
          conn = connection_create_listener(listensockaddr, type, address);
          tor_free(listensockaddr);
          tor_free(address);
        } else
          conn = NULL;

        if (!conn) {
          r = -1;
        } else {
          if (new_conns)
            smartlist_add(new_conns, conn);
        }
      });
  }

  if (free_launch_elts) {
    SMARTLIST_FOREACH(launch, config_line_t *, cfg_line,
                      config_free_lines(cfg_line));
  }
  smartlist_free(launch);

  return r;
}

/** Launch listeners for each port you should have open.  Only launch
 * listeners who are not already open, and only close listeners we no longer
 * want.
 *
 * Add all old conns that should be closed to <b>replaced_conns</b>.
 * Add all new connections to <b>new_conns</b>.
 */
int
retry_all_listeners(smartlist_t *replaced_conns,
                    smartlist_t *new_conns)
{
  or_options_t *options = get_options();

  if (retry_listeners(CONN_TYPE_OR_LISTENER, options->ORListenAddress,
                      options->ORPort, "0.0.0.0",
                      replaced_conns, new_conns, options->ClientOnly,
                      AF_INET)<0)
    return -1;
  if (retry_listeners(CONN_TYPE_DIR_LISTENER, options->DirListenAddress,
                      options->DirPort, "0.0.0.0",
                      replaced_conns, new_conns, options->ClientOnly,
                      AF_INET)<0)
    return -1;
  if (retry_listeners(CONN_TYPE_AP_LISTENER, options->SocksListenAddress,
                      options->SocksPort, "127.0.0.1",
                      replaced_conns, new_conns, 0,
                      AF_INET)<0)
    return -1;
  if (retry_listeners(CONN_TYPE_AP_TRANS_LISTENER, options->TransListenAddress,
                      options->TransPort, "127.0.0.1",
                      replaced_conns, new_conns, 0,
                      AF_INET)<0)
    return -1;
  if (retry_listeners(CONN_TYPE_AP_NATD_LISTENER, options->NatdListenAddress,
                      options->NatdPort, "127.0.0.1",
                      replaced_conns, new_conns, 0,
                      AF_INET)<0)
    return -1;
  if (retry_listeners(CONN_TYPE_AP_DNS_LISTENER, options->DNSListenAddress,
                      options->DNSPort, "127.0.0.1",
                      replaced_conns, new_conns, 0,
                      AF_INET)<0)
    return -1;
  if (retry_listeners(CONN_TYPE_CONTROL_LISTENER,
                      options->ControlListenAddress,
                      options->ControlPort, "127.0.0.1",
                      replaced_conns, new_conns, 0,
                      AF_INET)<0)
    return -1;
  if (retry_listeners(CONN_TYPE_CONTROL_LISTENER,
                      options->ControlSocket,
                      options->ControlSocket ? 1 : 0, NULL,
                      replaced_conns, new_conns, 0,
                      AF_UNIX)<0)
    return -1;

  return 0;
}

/** Return 1 if we should apply rate limiting to <b>conn</b>,
 * and 0 otherwise. Right now this just checks if it's an internal
 * IP address or an internal connection. */
static int
connection_is_rate_limited(connection_t *conn)
{
  if (conn->linked || is_internal_IP(conn->addr, 0))
    return 0;
  else
    return 1;
}

extern int global_read_bucket, global_write_bucket;
extern int global_relayed_read_bucket, global_relayed_write_bucket;

/** Did either global write bucket run dry last second? If so,
 * we are likely to run dry again this second, so be stingy with the
 * tokens we just put in. */
static int write_buckets_empty_last_second = 0;

/** How many seconds of no active local circuits will make the
 * connection revert to the "relayed" bandwidth class? */
#define CLIENT_IDLE_TIME_FOR_PRIORITY 30

/** Return 1 if <b>conn</b> should use tokens from the "relayed"
 * bandwidth rates, else 0. Currently, only OR conns with bandwidth
 * class 1, and directory conns that are serving data out, count.
 */
static int
connection_counts_as_relayed_traffic(connection_t *conn, time_t now)
{
  if (conn->type == CONN_TYPE_OR &&
      TO_OR_CONN(conn)->client_used + CLIENT_IDLE_TIME_FOR_PRIORITY < now)
    return 1;
  if (conn->type == CONN_TYPE_DIR && DIR_CONN_IS_SERVER(conn))
    return 1;
  return 0;
}

/** Helper function to decide how many bytes out of <b>global_bucket</b>
 * we're willing to use for this transaction. <b>base</b> is the size
 * of a cell on the network; <b>priority</b> says whether we should
 * write many of them or just a few; and <b>conn_bucket</b> (if
 * non-negative) provides an upper limit for our answer. */
static ssize_t
connection_bucket_round_robin(int base, int priority,
                              ssize_t global_bucket, ssize_t conn_bucket)
{
  ssize_t at_most;
  ssize_t num_bytes_high = (priority ? 32 : 16) * base;
  ssize_t num_bytes_low = (priority ? 4 : 2) * base;

  /* Do a rudimentary round-robin so one circuit can't hog a connection.
   * Pick at most 32 cells, at least 4 cells if possible, and if we're in
   * the middle pick 1/8 of the available bandwidth. */
  at_most = global_bucket / 8;
  at_most -= (at_most % base); /* round down */
  if (at_most > num_bytes_high) /* 16 KB, or 8 KB for low-priority */
    at_most = num_bytes_high;
  else if (at_most < num_bytes_low) /* 2 KB, or 1 KB for low-priority */
    at_most = num_bytes_low;

  if (at_most > global_bucket)
    at_most = global_bucket;

  if (conn_bucket >= 0 && at_most > conn_bucket)
    at_most = conn_bucket;

  if (at_most < 0)
    return 0;
  return at_most;
}

/** How many bytes at most can we read onto this connection? */
static ssize_t
connection_bucket_read_limit(connection_t *conn, time_t now)
{
  int base = connection_speaks_cells(conn) ?
               CELL_NETWORK_SIZE : RELAY_PAYLOAD_SIZE;