Trigger OOS on bind failures (fixes #40597)

  o Minor features (relays):

    - Trigger OOS when bind fails with EADDRINUSE. This improves fairness when

      a large number of exit connections are requested, and properly signals

      exhaustion to the network. Fixes issue 40597; patch by Alex Xu (Hello71).

             tor_socket_strerror(errno));

  }

  /*

   * We've got the socket open; give the OOS handler a chance to check

   * against configured maximum socket number, but tell it no exhaustion

   * failure.

   */

  connection_check_oos(get_n_open_sockets(), 0);

  if (bindaddr && bind(s, bindaddr, bindaddr_len) < 0) {

    *socket_error = tor_socket_errno(s);

    if (ERRNO_IS_EADDRINUSE(*socket_error)) {

      socket_failed_from_resource_exhaustion();

      connection_check_oos(get_n_open_sockets(), 1);

    } else {

      log_warn(LD_NET,"Error binding network socket: %s",

               tor_socket_strerror(*socket_error));

      connection_check_oos(get_n_open_sockets(), 0);

    }

    tor_close_socket(s);

    return -1;

  }

  /*

   * We've got the socket open and bound; give the OOS handler a chance to

   * check against configured maximum socket number, but tell it no exhaustion

   * failure.

   */

  connection_check_oos(get_n_open_sockets(), 0);

  tor_assert(options);

  if (options->ConstrainedSockets)

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