connection_or.c

关于tor匿名通信的源代码

             " has a cert but it's invalid. Closing.",
             safe_address, conn->_base.port);
        return -1;
    } else if (v<0) {
      log_info(LD_PROTOCOL,"Incoming connection gave us an invalid cert "
               "chain; ignoring.");
    } else {
      log_debug(LD_OR,"The certificate seems to be valid on %s connection "
                "with %s:%d", conn_type, safe_address, conn->_base.port);
    }
    check_no_tls_errors();
  }

  if (identity_rcvd) {
    has_identity = 1;
    crypto_pk_get_digest(identity_rcvd, digest_rcvd_out);
    if (crypto_pk_cmp_keys(get_identity_key(), identity_rcvd)<0) {
      conn->circ_id_type = CIRC_ID_TYPE_LOWER;
    } else {
      conn->circ_id_type = CIRC_ID_TYPE_HIGHER;
    }
    crypto_free_pk_env(identity_rcvd);
  } else {
    memset(digest_rcvd_out, 0, DIGEST_LEN);
    conn->circ_id_type = CIRC_ID_TYPE_NEITHER;
  }

  if (started_here && tor_digest_is_zero(conn->identity_digest)) {
    connection_or_set_identity_digest(conn, digest_rcvd_out);
    tor_free(conn->nickname);
    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);
    log_info(LD_OR, "Connected to router %s at %s:%d without knowing "
                    "its key. Hoping for the best.",
                    conn->nickname, conn->_base.address, conn->_base.port);
  }

  if (started_here) {
    int as_advertised = 1;
    tor_assert(has_cert);
    tor_assert(has_identity);
    if (memcmp(digest_rcvd_out, conn->identity_digest, DIGEST_LEN)) {
      /* I was aiming for a particular digest. I didn't get it! */
      char seen[HEX_DIGEST_LEN+1];
      char expected[HEX_DIGEST_LEN+1];
      base16_encode(seen, sizeof(seen), digest_rcvd_out, DIGEST_LEN);
      base16_encode(expected, sizeof(expected), conn->identity_digest,
                    DIGEST_LEN);
      log_fn(severity, LD_OR,
             "Tried connecting to router at %s:%d, but identity key was not "
             "as expected: wanted %s but got %s.",
             conn->_base.address, conn->_base.port, expected, seen);
      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_OR_IDENTITY);
      as_advertised = 0;
    }
    if (authdir_mode_tests_reachability(options)) {
      /* We initiated this connection to address:port.  Drop all routers
       * with the same address:port and a different key.
       */
      dirserv_orconn_tls_done(conn->_base.address, conn->_base.port,
                              digest_rcvd_out, as_advertised);
    }
    if (!as_advertised)
      return -1;
  }
  return 0;
}

/** The tls handshake is finished.
 *
 * Make sure we are happy with the person we just handshaked with.
 *
 * If he initiated the connection, make sure he's not already connected,
 * then initialize conn from the information in router.
 *
 * If all is successful, call circuit_n_conn_done() to handle events
 * that have been pending on the <tls handshake completion. Also set the
 * directory to be dirty (only matters if I'm an authdirserver).
 */
static int
connection_tls_finish_handshake(or_connection_t *conn)
{
  char digest_rcvd[DIGEST_LEN];
  int started_here = connection_or_nonopen_was_started_here(conn);

  log_debug(LD_OR,"tls handshake with %s done. verifying.",
            conn->_base.address);

  directory_set_dirty();

  if (connection_or_check_valid_tls_handshake(conn, started_here,
                                              digest_rcvd) < 0)
    return -1;

  if (tor_tls_used_v1_handshake(conn->tls)) {
    conn->link_proto = 1;
    if (!started_here) {
      connection_or_init_conn_from_address(conn,conn->_base.addr,
                                           conn->_base.port, digest_rcvd, 0);
    }
    return connection_or_set_state_open(conn);
  } else {
    conn->_base.state = OR_CONN_STATE_OR_HANDSHAKING;
    if (connection_init_or_handshake_state(conn, started_here) < 0)
      return -1;
    if (!started_here) {
      connection_or_init_conn_from_address(conn,conn->_base.addr,
                                           conn->_base.port, digest_rcvd, 0);
    }
    return connection_or_send_versions(conn);
  }
}

/** Allocate a new connection handshake state for the connection
 * <b>conn</b>.  Return 0 on success, -1 on failure. */
static int
connection_init_or_handshake_state(or_connection_t *conn, int started_here)
{
  or_handshake_state_t *s;
  s = conn->handshake_state = tor_malloc_zero(sizeof(or_handshake_state_t));
  s->started_here = started_here ? 1 : 0;
  return 0;
}

/** Free all storage held by <b>state</b>. */
void
or_handshake_state_free(or_handshake_state_t *state)
{
  tor_assert(state);
  memset(state, 0xBE, sizeof(or_handshake_state_t));
  tor_free(state);
}

/** Set <b>conn</b>'s state to OR_CONN_STATE_OPEN, and tell other subsystems
 * as appropriate.  Called when we are done with all TLS and OR handshaking.
 */
int
connection_or_set_state_open(or_connection_t *conn)
{
  int started_here = connection_or_nonopen_was_started_here(conn);
  time_t now = time(NULL);
  conn->_base.state = OR_CONN_STATE_OPEN;
  control_event_or_conn_status(conn, OR_CONN_EVENT_CONNECTED, 0);

  if (started_here) {
    rep_hist_note_connect_succeeded(conn->identity_digest, now);
    if (entry_guard_register_connect_status(conn->identity_digest,
                                            1, now) < 0) {
      /* Close any circuits pending on this conn. We leave it in state
       * 'open' though, because it didn't actually *fail* -- we just
       * chose not to use it. (Otherwise
       * connection_about_to_close_connection() will call a big pile of
       * functions to indicate we shouldn't try it again.) */
      circuit_n_conn_done(conn, 0);
      return -1;
    }
    router_set_status(conn->identity_digest, 1);
  } else {
    /* only report it to the geoip module if it's not a known router */
    if (!router_get_by_digest(conn->identity_digest))
      geoip_note_client_seen(TO_CONN(conn)->addr, now);
  }
  if (conn->handshake_state) {
    or_handshake_state_free(conn->handshake_state);
    conn->handshake_state = NULL;
  }
  connection_start_reading(TO_CONN(conn));
  circuit_n_conn_done(conn, 1); /* send the pending creates, if any. */

  return 0;
}

/** Pack <b>cell</b> into wire-format, and write it onto <b>conn</b>'s outbuf.
 * For cells that use or affect a circuit, this should only be called by
 * connection_or_flush_from_first_active_circuit().
 */
void
connection_or_write_cell_to_buf(const cell_t *cell, or_connection_t *conn)
{
  packed_cell_t networkcell;

  tor_assert(cell);
  tor_assert(conn);

  cell_pack(&networkcell, cell);

  connection_write_to_buf(networkcell.body, CELL_NETWORK_SIZE, TO_CONN(conn));

  if (cell->command != CELL_PADDING)
    conn->timestamp_last_added_nonpadding = time(NULL);
}

/** Pack a variable-length <b>cell</b> into wire-format, and write it onto
 * <b>conn</b>'s outbuf.  Right now, this <em>DOES NOT</em> support cells that
 * affect a circuit.
 */
void
connection_or_write_var_cell_to_buf(const var_cell_t *cell,
                                    or_connection_t *conn)
{
  char hdr[VAR_CELL_HEADER_SIZE];
  tor_assert(cell);
  tor_assert(conn);
  var_cell_pack_header(cell, hdr);
  connection_write_to_buf(hdr, sizeof(hdr), TO_CONN(conn));
  connection_write_to_buf(cell->payload, cell->payload_len, TO_CONN(conn));
  if (cell->command != CELL_PADDING)
    conn->timestamp_last_added_nonpadding = time(NULL);
}

/** See whether there's a variable-length cell waiting on <b>conn</b>'s
 * inbuf.  Return values as for fetch_var_cell_from_buf(). */
static int
connection_fetch_var_cell_from_buf(or_connection_t *conn, var_cell_t **out)
{
  return fetch_var_cell_from_buf(conn->_base.inbuf, out, conn->link_proto);
}

/** Process cells from <b>conn</b>'s inbuf.
 *
 * Loop: while inbuf contains a cell, pull it off the inbuf, unpack it,
 * and hand it to command_process_cell().
 *
 * Always return 0.
 */
static int
connection_or_process_cells_from_inbuf(or_connection_t *conn)
{
  var_cell_t *var_cell;

  while (1) {
    log_debug(LD_OR,
              "%d: starting, inbuf_datalen %d (%d pending in tls object).",
              conn->_base.s,(int)buf_datalen(conn->_base.inbuf),
              tor_tls_get_pending_bytes(conn->tls));
    if (connection_fetch_var_cell_from_buf(conn, &var_cell)) {
      if (!var_cell)
        return 0; /* not yet. */
      command_process_var_cell(var_cell, conn);
      var_cell_free(var_cell);
    } else {
      char buf[CELL_NETWORK_SIZE];
      cell_t cell;
      if (buf_datalen(conn->_base.inbuf) < CELL_NETWORK_SIZE) /* whole response
                                                                 available? */
        return 0; /* not yet */

      connection_fetch_from_buf(buf, CELL_NETWORK_SIZE, TO_CONN(conn));

      /* retrieve cell info from buf (create the host-order struct from the
       * network-order string) */
      cell_unpack(&cell, buf);

      command_process_cell(&cell, conn);
    }
  }
}

/** Write a destroy cell with circ ID <b>circ_id</b> and reason <b>reason</b>
 * onto OR connection <b>conn</b>.  Don't perform range-checking on reason:
 * we may want to propagate reasons from other cells.
 *
 * Return 0.
 */
int
connection_or_send_destroy(uint16_t circ_id, or_connection_t *conn, int reason)
{
  cell_t cell;

  tor_assert(conn);

  memset(&cell, 0, sizeof(cell_t));
  cell.circ_id = circ_id;
  cell.command = CELL_DESTROY;
  cell.payload[0] = (uint8_t) reason;
  log_debug(LD_OR,"Sending destroy (circID %d).", circ_id);

  /* XXXX It's possible that under some circumstances, we want the destroy
   * to take precedence over other data waiting on the circuit's cell queue.
   */

  connection_or_write_cell_to_buf(&cell, conn);
  return 0;
}

/** Array of recognized link protocol versions. */
static const uint16_t or_protocol_versions[] = { 1, 2 };
/** Number of versions in <b>or_protocol_versions</b>. */
static const int n_or_protocol_versions =
  (int)( sizeof(or_protocol_versions)/sizeof(uint16_t) );

/** Return true iff <b>v</b> is a link protocol version that this Tor
 * implementation believes it can support. */
int
is_or_protocol_version_known(uint16_t v)
{
  int i;
  for (i = 0; i < n_or_protocol_versions; ++i) {
    if (or_protocol_versions[i] == v)
      return 1;
  }
  return 0;
}

/** Send a VERSIONS cell on <b>conn</b>, telling the other host about the
 * link protocol versions that this Tor can support. */
static int
connection_or_send_versions(or_connection_t *conn)
{
  var_cell_t *cell;
  int i;
  tor_assert(conn->handshake_state &&
             !conn->handshake_state->sent_versions_at);
  cell = var_cell_new(n_or_protocol_versions * 2);
  cell->command = CELL_VERSIONS;
  for (i = 0; i < n_or_protocol_versions; ++i) {
    uint16_t v = or_protocol_versions[i];
    set_uint16(cell->payload+(2*i), htons(v));
  }

  connection_or_write_var_cell_to_buf(cell, conn);
  conn->handshake_state->sent_versions_at = time(NULL);

  var_cell_free(cell);
  return 0;
}

/** Send a NETINFO cell on <b>conn</b>, telling the other server what we know
 * about their address, our address, and the current time. */
int
connection_or_send_netinfo(or_connection_t *conn)
{
  cell_t cell;
  time_t now = time(NULL);
  routerinfo_t *me;

  memset(&cell, 0, sizeof(cell_t));
  cell.command = CELL_NETINFO;

  /* Their address. */
  set_uint32(cell.payload, htonl((uint32_t)now));
  cell.payload[4] = RESOLVED_TYPE_IPV4;
  cell.payload[5] = 4;
  set_uint32(cell.payload+6, htonl(conn->_base.addr));

  /* My address. */
  if ((me = router_get_my_routerinfo())) {
    cell.payload[10] = 1; /* only one address is supported. */
    cell.payload[11] = RESOLVED_TYPE_IPV4;
    cell.payload[12] = 4;
    set_uint32(cell.payload+13, htonl(me->addr));
  } else {
    cell.payload[10] = 0;
  }

  connection_or_write_cell_to_buf(&cell, conn);

  return 0;
}