connection_or.c

关于tor匿名通信的源代码

                   addrbuf, conn->port);
    }
    connection_write_to_buf(buf, strlen(buf), conn);
    conn->state = OR_CONN_STATE_PROXY_FLUSHING;
    return 0;
  }

  if (connection_tls_start_handshake(or_conn, 0) < 0) {
    /* TLS handshaking error of some kind. */
    connection_mark_for_close(conn);
    return -1;
  }
  return 0;
}

/** If we don't necessarily know the router we're connecting to, but we
 * have an addr/port/id_digest, then fill in as much as we can. Start
 * by checking to see if this describes a router we know. */
static void
connection_or_init_conn_from_address(or_connection_t *conn,
                                     uint32_t addr, uint16_t port,
                                     const char *id_digest,
                                     int started_here)
{
  or_options_t *options = get_options();
  routerinfo_t *r = router_get_by_digest(id_digest);
  conn->bandwidthrate = (int)options->BandwidthRate;
  conn->read_bucket = conn->bandwidthburst = (int)options->BandwidthBurst;
  connection_or_set_identity_digest(conn, id_digest);
  conn->_base.addr = addr;
  conn->_base.port = port;
  conn->real_addr = addr;
  if (r) {
    if (conn->_base.addr == r->addr)
      conn->is_canonical = 1;
    if (!started_here) {
      /* Override the addr/port, so our log messages will make sense.
       * This is dangerous, since if we ever try looking up a conn by
       * its actual addr/port, we won't remember. Careful! */
      /* XXXX021 arma: this is stupid, and it's the reason we need real_addr
       * to track is_canonical properly.  What requires it? */
      /* XXXX <arma> i believe the reason we did this, originally, is because
       * we wanted to log what OR a connection was to, and if we logged the
       * right IP address and port 56244, that wouldn't be as helpful. now we
       * log the "right" port too, so we know if it's moria1 or moria2.
      */
      conn->_base.addr = r->addr;
      conn->_base.port = r->or_port;
    }
    conn->nickname = tor_strdup(r->nickname);
    tor_free(conn->_base.address);
    conn->_base.address = tor_strdup(r->address);
  } else {
    const char *n;
    /* If we're an authoritative directory server, we may know a
     * nickname for this router. */
    n = dirserv_get_nickname_by_digest(id_digest);
    if (n) {
      conn->nickname = tor_strdup(n);
    } else {
      conn->nickname = tor_malloc(HEX_DIGEST_LEN+2);
      conn->nickname[0] = '$';
      base16_encode(conn->nickname+1, HEX_DIGEST_LEN+1,
                    conn->identity_digest, DIGEST_LEN);
    }
    tor_free(conn->_base.address);
    conn->_base.address = tor_dup_addr(addr);
  }
}

/** Return the best connection of type OR with the
 * digest <b>digest</b> that we have, or NULL if we have none.
 *
 * 1) Don't return it if it's marked for close.
 * 2) If there are any open conns, ignore non-open conns.
 * 3) If there are any non-obsolete conns, ignore obsolete conns.
 * 4) Then if there are any non-empty conns, ignore empty conns.
 * 5) Of the remaining conns, prefer newer conns.
 */
or_connection_t *
connection_or_get_by_identity_digest(const char *digest)
{
  int newer;
  or_connection_t *conn, *best=NULL;

  if (!orconn_identity_map)
    return NULL;

  conn = digestmap_get(orconn_identity_map, digest);

  for (; conn; conn = conn->next_with_same_id) {
    tor_assert(conn->_base.magic == OR_CONNECTION_MAGIC);
    tor_assert(conn->_base.type == CONN_TYPE_OR);
    tor_assert(!memcmp(conn->identity_digest, digest, DIGEST_LEN));
    if (conn->_base.marked_for_close)
      continue;
    if (!best) {
      best = conn; /* whatever it is, it's better than nothing. */
      continue;
    }
    if (best->_base.state == OR_CONN_STATE_OPEN &&
        conn->_base.state != OR_CONN_STATE_OPEN)
      continue; /* avoid non-open conns if we can */
    newer = best->_base.timestamp_created < conn->_base.timestamp_created;

    if (best->is_canonical && !conn->is_canonical)
      continue; /* A canonical connection is best. */

    if (!best->_base.or_is_obsolete && conn->_base.or_is_obsolete)
      continue; /* We never prefer obsolete over non-obsolete connections. */

    if (
      /* We prefer non-obsolete connections: */
        (best->_base.or_is_obsolete && !conn->_base.or_is_obsolete) ||
      /* If both have circuits we prefer the newer: */
        (best->n_circuits && conn->n_circuits && newer) ||
      /* If neither has circuits we prefer the newer: */
        (!best->n_circuits && !conn->n_circuits && newer) ||
      /* We prefer connections with circuits: */
        (!best->n_circuits && conn->n_circuits)) {
      best = conn;
    };
  }
  return best;
}

/** Launch a new OR connection to <b>addr</b>:<b>port</b> and expect to
 * handshake with an OR with identity digest <b>id_digest</b>.
 *
 * If <b>id_digest</b> is me, do nothing. If we're already connected to it,
 * return that connection. If the connect() is in progress, set the
 * new conn's state to 'connecting' and return it. If connect() succeeds,
 * call connection_tls_start_handshake() on it.
 *
 * This function is called from router_retry_connections(), for
 * ORs connecting to ORs, and circuit_establish_circuit(), for
 * OPs connecting to ORs.
 *
 * Return the launched conn, or NULL if it failed.
 */
or_connection_t *
connection_or_connect(uint32_t addr, uint16_t port, const char *id_digest)
{
  or_connection_t *conn;
  or_options_t *options = get_options();

  tor_assert(id_digest);

  if (server_mode(options) && router_digest_is_me(id_digest)) {
    log_info(LD_PROTOCOL,"Client asked me to connect to myself. Refusing.");
    return NULL;
  }

  conn = TO_OR_CONN(connection_new(CONN_TYPE_OR, AF_INET));

  /* set up conn so it's got all the data we need to remember */
  connection_or_init_conn_from_address(conn, addr, port, id_digest, 1);
  conn->_base.state = OR_CONN_STATE_CONNECTING;
  control_event_or_conn_status(conn, OR_CONN_EVENT_LAUNCHED, 0);

  if (options->HttpsProxy) {
    /* we shouldn't connect directly. use the https proxy instead. */
    addr = options->HttpsProxyAddr;
    port = options->HttpsProxyPort;
  }

  switch (connection_connect(TO_CONN(conn), conn->_base.address, addr, port)) {
    case -1:
      /* If the connection failed immediately, and we're using
       * an https proxy, our https proxy is down. Don't blame the
       * Tor server. */
      if (!options->HttpsProxy) {
        entry_guard_register_connect_status(conn->identity_digest, 0,
                                            time(NULL));
        router_set_status(conn->identity_digest, 0);
      }
      control_event_or_conn_status(conn, OR_CONN_EVENT_FAILED,
              END_OR_CONN_REASON_TCP_REFUSED);
      connection_free(TO_CONN(conn));
      return NULL;
    case 0:
      connection_watch_events(TO_CONN(conn), EV_READ | EV_WRITE);
      /* writable indicates finish, readable indicates broken link,
         error indicates broken link on windows */
      return conn;
    /* case 1: fall through */
  }

  if (connection_or_finished_connecting(conn) < 0) {
    /* already marked for close */
    return NULL;
  }
  return conn;
}

/** Begin the tls handshake with <b>conn</b>. <b>receiving</b> is 0 if
 * we initiated the connection, else it's 1.
 *
 * Assign a new tls object to conn->tls, begin reading on <b>conn</b>, and
 * pass <b>conn</b> to connection_tls_continue_handshake().
 *
 * Return -1 if <b>conn</b> is broken, else return 0.
 */
int
connection_tls_start_handshake(or_connection_t *conn, int receiving)
{
  conn->_base.state = OR_CONN_STATE_TLS_HANDSHAKING;
  conn->tls = tor_tls_new(conn->_base.s, receiving);
  tor_tls_set_logged_address(conn->tls, escaped_safe_str(conn->_base.address));
  if (!conn->tls) {
    log_warn(LD_BUG,"tor_tls_new failed. Closing.");
    return -1;
  }
  connection_start_reading(TO_CONN(conn));
  log_debug(LD_OR,"starting TLS handshake on fd %d", conn->_base.s);
  note_crypto_pk_op(receiving ? TLS_HANDSHAKE_S : TLS_HANDSHAKE_C);

  if (connection_tls_continue_handshake(conn) < 0) {
    return -1;
  }
  return 0;
}

/** Invoked on the server side from inside tor_tls_read() when the server
 * gets a successful TLS renegotiation from the client. */
static void
connection_or_tls_renegotiated_cb(tor_tls_t *tls, void *_conn)
{
  or_connection_t *conn = _conn;
  (void)tls;

  /* Don't invoke this again. */
  tor_tls_set_renegotiate_callback(tls, NULL, NULL);

  if (connection_tls_finish_handshake(conn) < 0) {
    /* XXXX_TLS double-check that it's ok to do this from inside read. */
    /* XXXX_TLS double-check that this verifies certificates. */
    connection_mark_for_close(TO_CONN(conn));
  }
}

/** Move forward with the tls handshake. If it finishes, hand
 * <b>conn</b> to connection_tls_finish_handshake().
 *
 * Return -1 if <b>conn</b> is broken, else return 0.
 */
int
connection_tls_continue_handshake(or_connection_t *conn)
{
  int result;
  check_no_tls_errors();
 again:
  if (conn->_base.state == OR_CONN_STATE_TLS_CLIENT_RENEGOTIATING) {
    // log_notice(LD_OR, "Renegotiate with %p", conn->tls);
    result = tor_tls_renegotiate(conn->tls);
    // log_notice(LD_OR, "Result: %d", result);
  } else {
    tor_assert(conn->_base.state == OR_CONN_STATE_TLS_HANDSHAKING);
    // log_notice(LD_OR, "Continue handshake with %p", conn->tls);
    result = tor_tls_handshake(conn->tls);
    // log_notice(LD_OR, "Result: %d", result);
  }
  switch (result) {
    CASE_TOR_TLS_ERROR_ANY:
    log_info(LD_OR,"tls error [%s]. breaking connection.",
             tor_tls_err_to_string(result));
      return -1;
    case TOR_TLS_DONE:
      if (! tor_tls_used_v1_handshake(conn->tls)) {
        if (!tor_tls_is_server(conn->tls)) {
          if (conn->_base.state == OR_CONN_STATE_TLS_HANDSHAKING) {
            // log_notice(LD_OR,"Done. state was TLS_HANDSHAKING.");
            conn->_base.state = OR_CONN_STATE_TLS_CLIENT_RENEGOTIATING;
            goto again;
          }
          // log_notice(LD_OR,"Done. state was %d.", conn->_base.state);
        } else {
          /* improved handshake, but not a client. */
          tor_tls_set_renegotiate_callback(conn->tls,
                                           connection_or_tls_renegotiated_cb,
                                           conn);
          conn->_base.state = OR_CONN_STATE_TLS_SERVER_RENEGOTIATING;
          connection_stop_writing(TO_CONN(conn));
          connection_start_reading(TO_CONN(conn));
          return 0;
        }
      }
      return connection_tls_finish_handshake(conn);
    case TOR_TLS_WANTWRITE:
      connection_start_writing(TO_CONN(conn));
      log_debug(LD_OR,"wanted write");
      return 0;
    case TOR_TLS_WANTREAD: /* handshaking conns are *always* reading */
      log_debug(LD_OR,"wanted read");
      return 0;
    case TOR_TLS_CLOSE:
      log_info(LD_OR,"tls closed. breaking connection.");
      return -1;
  }
  return 0;
}

/** Return 1 if we initiated this connection, or 0 if it started
 * out as an incoming connection.
 */
int
connection_or_nonopen_was_started_here(or_connection_t *conn)
{
  tor_assert(conn->_base.type == CONN_TYPE_OR);
  if (!conn->tls)
    return 1; /* it's still in proxy states or something */
  if (conn->handshake_state)
    return conn->handshake_state->started_here;
  return !tor_tls_is_server(conn->tls);
}

/** <b>Conn</b> just completed its handshake. Return 0 if all is well, and
 * return -1 if he is lying, broken, or otherwise something is wrong.
 *
 * If we initiated this connection (<b>started_here</b> is true), make sure
 * the other side sent sent a correctly formed certificate. If I initiated the
 * connection, make sure it's the right guy.
 *
 * Otherwise (if we _didn't_ initiate this connection), it's okay for
 * the certificate to be weird or absent.
 *
 * If we return 0, and the certificate is as expected, write a hash of the
 * identity key into digest_rcvd, which must have DIGEST_LEN space in it. (If
 * we return -1 this buffer is undefined.)  If the certificate is invalid
 * or missing on an incoming connection, we return 0 and set digest_rcvd to
 * DIGEST_LEN 0 bytes.
 *
 * As side effects,
 * 1) Set conn->circ_id_type according to tor-spec.txt.
 * 2) If we're an authdirserver and we initiated the connection: drop all
 *    descriptors that claim to be on that IP/port but that aren't
 *    this guy; and note that this guy is reachable.
 */
static int
connection_or_check_valid_tls_handshake(or_connection_t *conn,
                                        int started_here,
                                        char *digest_rcvd_out)
{
  crypto_pk_env_t *identity_rcvd=NULL;
  or_options_t *options = get_options();
  int severity = server_mode(options) ? LOG_PROTOCOL_WARN : LOG_WARN;
  const char *safe_address =
    started_here ? conn->_base.address : safe_str(conn->_base.address);
  const char *conn_type = started_here ? "outgoing" : "incoming";
  int has_cert = 0, has_identity=0;

  check_no_tls_errors();
  has_cert = tor_tls_peer_has_cert(conn->tls);
  if (started_here && !has_cert) {
    log_info(LD_PROTOCOL,"Tried connecting to router at %s:%d, but it didn't "
             "send a cert! Closing.",
             safe_address, conn->_base.port);
    return -1;
  } else if (!has_cert) {
    log_debug(LD_PROTOCOL,"Got incoming connection with no certificate. "
              "That's ok.");
  }
  check_no_tls_errors();

  if (has_cert) {
    int v = tor_tls_verify(started_here?severity:LOG_INFO,
                           conn->tls, &identity_rcvd);
    if (started_here && v<0) {
      log_fn(severity,LD_OR,"Tried connecting to router at %s:%d: It"