voc Pennington <hp@redhat.com>

	* dbus/dbus-server.c (dbus_server_listen): change how this works
	to be able to delegate to a set of handlers that can succeed,
	fail, or choose not to handle. Allows us to have
	dbus_server_listen_platform_specific.

	* dbus/dbus-server-socket.c (_dbus_server_new_for_tcp_socket):
	factor out the tcp socket stuff to be used on windows, leaving
	unix domain socket only in dbus-socket-unix.c

	* dbus/dbus-transport-socket.c
	(_dbus_transport_new_for_tcp_socket): factor out the tcp socket
	stuff to be used on windows, leaving unix domain socket only
	in dbus-transport-unix.c

	* dbus/dbus-connection.c (dbus_connection_get_unix_user): insert
	temporary hack to be sure this fails on windows
	(dbus_connection_get_unix_process_id): ditto

1 files changed, 1255 insertions, 0 deletions

diff --git a/dbus/dbus-transport-socket.c b/dbus/dbus-transport-socket.c
new file mode 100644
index 00000000..64991181
--- /dev/null
+++ b/dbus/dbus-transport-socket.c
@@ -0,0 +1,1255 @@
+/* -*- mode: C; c-file-style: "gnu" -*- */
+/* dbus-transport-socket.c  Socket subclasses of DBusTransport
+ *
+ * Copyright (C) 2002, 2003, 2004, 2006  Red Hat Inc.
+ *
+ * Licensed under the Academic Free License version 2.1
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include "dbus-internals.h"
+#include "dbus-connection-internal.h"
+#include "dbus-transport-socket.h"
+#include "dbus-transport-protected.h"
+#include "dbus-watch.h"
+
+
+/**
+ * @defgroup DBusTransportSocket DBusTransport implementations for sockets
+ * @ingroup  DBusInternals
+ * @brief Implementation details of DBusTransport on sockets
+ *
+ * @{
+ */
+
+/**
+ * Opaque object representing a socket file descriptor transport.
+ */
+typedef struct DBusTransportSocket DBusTransportSocket;
+
+/**
+ * Implementation details of DBusTransportSocket. All members are private.
+ */
+struct DBusTransportSocket
+{
+  DBusTransport base;                   /**< Parent instance */
+  int fd;                               /**< File descriptor. */
+  DBusWatch *read_watch;                /**< Watch for readability. */
+  DBusWatch *write_watch;               /**< Watch for writability. */
+
+  int max_bytes_read_per_iteration;     /**< To avoid blocking too long. */
+  int max_bytes_written_per_iteration;  /**< To avoid blocking too long. */
+
+  int message_bytes_written;            /**< Number of bytes of current
+                                         *   outgoing message that have
+                                         *   been written.
+                                         */
+  DBusString encoded_outgoing;          /**< Encoded version of current
+                                         *   outgoing message.
+                                         */
+  DBusString encoded_incoming;          /**< Encoded version of current
+                                         *   incoming data.
+                                         */
+};
+
+static void
+free_watches (DBusTransport *transport)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+
+  _dbus_verbose ("%s start\n", _DBUS_FUNCTION_NAME);
+  
+  if (socket_transport->read_watch)
+    {
+      if (transport->connection)
+        _dbus_connection_remove_watch_unlocked (transport->connection,
+                                                socket_transport->read_watch);
+      _dbus_watch_invalidate (socket_transport->read_watch);
+      _dbus_watch_unref (socket_transport->read_watch);
+      socket_transport->read_watch = NULL;
+    }
+
+  if (socket_transport->write_watch)
+    {
+      if (transport->connection)
+        _dbus_connection_remove_watch_unlocked (transport->connection,
+                                                socket_transport->write_watch);
+      _dbus_watch_invalidate (socket_transport->write_watch);
+      _dbus_watch_unref (socket_transport->write_watch);
+      socket_transport->write_watch = NULL;
+    }
+
+  _dbus_verbose ("%s end\n", _DBUS_FUNCTION_NAME);
+}
+
+static void
+socket_finalize (DBusTransport *transport)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+
+  _dbus_verbose ("%s\n", _DBUS_FUNCTION_NAME);
+  
+  free_watches (transport);
+
+  _dbus_string_free (&socket_transport->encoded_outgoing);
+  _dbus_string_free (&socket_transport->encoded_incoming);
+  
+  _dbus_transport_finalize_base (transport);
+
+  _dbus_assert (socket_transport->read_watch == NULL);
+  _dbus_assert (socket_transport->write_watch == NULL);
+  
+  dbus_free (transport);
+}
+
+static void
+check_write_watch (DBusTransport *transport)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+  dbus_bool_t needed;
+
+  if (transport->connection == NULL)
+    return;
+
+  if (transport->disconnected)
+    {
+      _dbus_assert (socket_transport->write_watch == NULL);
+      return;
+    }
+  
+  _dbus_transport_ref (transport);
+
+  if (_dbus_transport_get_is_authenticated (transport))
+    needed = _dbus_connection_has_messages_to_send_unlocked (transport->connection);
+  else
+    {
+      if (transport->send_credentials_pending)
+        needed = TRUE;
+      else
+        {
+          DBusAuthState auth_state;
+          
+          auth_state = _dbus_auth_do_work (transport->auth);
+          
+          /* If we need memory we install the write watch just in case,
+           * if there's no need for it, it will get de-installed
+           * next time we try reading.
+           */
+          if (auth_state == DBUS_AUTH_STATE_HAVE_BYTES_TO_SEND ||
+              auth_state == DBUS_AUTH_STATE_WAITING_FOR_MEMORY)
+            needed = TRUE;
+          else
+            needed = FALSE;
+        }
+    }
+
+  _dbus_verbose ("check_write_watch(): needed = %d on connection %p watch %p fd = %d outgoing messages exist %d\n",
+                 needed, transport->connection, socket_transport->write_watch,
+                 socket_transport->fd,
+                 _dbus_connection_has_messages_to_send_unlocked (transport->connection));
+
+  _dbus_connection_toggle_watch_unlocked (transport->connection,
+                                          socket_transport->write_watch,
+                                          needed);
+
+  _dbus_transport_unref (transport);
+}
+
+static void
+check_read_watch (DBusTransport *transport)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+  dbus_bool_t need_read_watch;
+
+  _dbus_verbose ("%s: fd = %d\n",
+                 _DBUS_FUNCTION_NAME, socket_transport->fd);
+  
+  if (transport->connection == NULL)
+    return;
+
+  if (transport->disconnected)
+    {
+      _dbus_assert (socket_transport->read_watch == NULL);
+      return;
+    }
+  
+  _dbus_transport_ref (transport);
+
+  if (_dbus_transport_get_is_authenticated (transport))
+    need_read_watch =
+      _dbus_counter_get_value (transport->live_messages_size) < transport->max_live_messages_size;
+  else
+    {
+      if (transport->receive_credentials_pending)
+        need_read_watch = TRUE;
+      else
+        {
+          /* The reason to disable need_read_watch when not WAITING_FOR_INPUT
+           * is to avoid spinning on the file descriptor when we're waiting
+           * to write or for some other part of the auth process
+           */
+          DBusAuthState auth_state;
+          
+          auth_state = _dbus_auth_do_work (transport->auth);
+
+          /* If we need memory we install the read watch just in case,
+           * if there's no need for it, it will get de-installed
+           * next time we try reading. If we're authenticated we
+           * install it since we normally have it installed while
+           * authenticated.
+           */
+          if (auth_state == DBUS_AUTH_STATE_WAITING_FOR_INPUT ||
+              auth_state == DBUS_AUTH_STATE_WAITING_FOR_MEMORY ||
+              auth_state == DBUS_AUTH_STATE_AUTHENTICATED)
+            need_read_watch = TRUE;
+          else
+            need_read_watch = FALSE;
+        }
+    }
+
+  _dbus_verbose ("  setting read watch enabled = %d\n", need_read_watch);
+  _dbus_connection_toggle_watch_unlocked (transport->connection,
+                                          socket_transport->read_watch,
+                                          need_read_watch);
+
+  _dbus_transport_unref (transport);
+}
+
+static void
+do_io_error (DBusTransport *transport)
+{
+  _dbus_transport_ref (transport);
+  _dbus_transport_disconnect (transport);
+  _dbus_transport_unref (transport);
+}
+
+/* return value is whether we successfully read any new data. */
+static dbus_bool_t
+read_data_into_auth (DBusTransport *transport,
+                     dbus_bool_t   *oom)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+  DBusString *buffer;
+  int bytes_read;
+  
+  *oom = FALSE;
+
+  _dbus_auth_get_buffer (transport->auth, &buffer);
+  
+  bytes_read = _dbus_read_socket (socket_transport->fd,
+                                  buffer, socket_transport->max_bytes_read_per_iteration);
+
+  _dbus_auth_return_buffer (transport->auth, buffer,
+                            bytes_read > 0 ? bytes_read : 0);
+
+  if (bytes_read > 0)
+    {
+      _dbus_verbose (" read %d bytes in auth phase\n", bytes_read);
+
+      return TRUE;
+    }
+  else if (bytes_read < 0)
+    {
+      /* EINTR already handled for us */
+
+      if (errno == ENOMEM)
+        {
+          *oom = TRUE;
+        }
+      else if (errno == EAGAIN ||
+               errno == EWOULDBLOCK)
+        ; /* do nothing, just return FALSE below */
+      else
+        {
+          _dbus_verbose ("Error reading from remote app: %s\n",
+                         _dbus_strerror (errno));
+          do_io_error (transport);
+        }
+
+      return FALSE;
+    }
+  else
+    {
+      _dbus_assert (bytes_read == 0);
+      
+      _dbus_verbose ("Disconnected from remote app\n");
+      do_io_error (transport);
+
+      return FALSE;
+    }
+}
+
+/* Return value is whether we successfully wrote any bytes */
+static dbus_bool_t
+write_data_from_auth (DBusTransport *transport)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+  int bytes_written;
+  const DBusString *buffer;
+
+  if (!_dbus_auth_get_bytes_to_send (transport->auth,
+                                     &buffer))
+    return FALSE;
+  
+  bytes_written = _dbus_write_socket (socket_transport->fd,
+                                      buffer,
+                                      0, _dbus_string_get_length (buffer));
+
+  if (bytes_written > 0)
+    {
+      _dbus_auth_bytes_sent (transport->auth, bytes_written);
+      return TRUE;
+    }
+  else if (bytes_written < 0)
+    {
+      /* EINTR already handled for us */
+      
+      if (errno == EAGAIN ||
+          errno == EWOULDBLOCK)
+        ;
+      else
+        {
+          _dbus_verbose ("Error writing to remote app: %s\n",
+                         _dbus_strerror (errno));
+          do_io_error (transport);
+        }
+    }
+
+  return FALSE;
+}
+
+static void
+exchange_credentials (DBusTransport *transport,
+                      dbus_bool_t    do_reading,
+                      dbus_bool_t    do_writing)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+
+  if (do_writing && transport->send_credentials_pending)
+    {
+      if (_dbus_send_credentials_unix_socket (socket_transport->fd,
+                                              NULL))
+        {
+          transport->send_credentials_pending = FALSE;
+        }
+      else
+        {
+          _dbus_verbose ("Failed to write credentials\n");
+          do_io_error (transport);
+        }
+    }
+  
+  if (do_reading && transport->receive_credentials_pending)
+    {
+      if (_dbus_read_credentials_unix_socket (socket_transport->fd,
+                                              &transport->credentials,
+                                              NULL))
+        {
+          transport->receive_credentials_pending = FALSE;
+        }
+      else
+        {
+          _dbus_verbose ("Failed to read credentials\n");
+          do_io_error (transport);
+        }
+    }
+
+  if (!(transport->send_credentials_pending ||
+        transport->receive_credentials_pending))
+    {
+      _dbus_auth_set_credentials (transport->auth,
+                                  &transport->credentials);
+    }
+}
+
+static dbus_bool_t
+do_authentication (DBusTransport *transport,
+                   dbus_bool_t    do_reading,
+                   dbus_bool_t    do_writing,
+		   dbus_bool_t   *auth_completed)
+{
+  dbus_bool_t oom;
+  dbus_bool_t orig_auth_state;
+
+  oom = FALSE;
+  
+  orig_auth_state = _dbus_transport_get_is_authenticated (transport);
+
+  /* This is essential to avoid the check_write_watch() at the end,
+   * we don't want to add a write watch in do_iteration before
+   * we try writing and get EAGAIN
+   */
+  if (orig_auth_state)
+    {
+      if (auth_completed)
+        *auth_completed = FALSE;
+      return TRUE;
+    }
+  
+  _dbus_transport_ref (transport);
+  
+  while (!_dbus_transport_get_is_authenticated (transport) &&
+         _dbus_transport_get_is_connected (transport))
+    {      
+      exchange_credentials (transport, do_reading, do_writing);
+      
+      if (transport->send_credentials_pending ||
+          transport->receive_credentials_pending)
+        {
+          _dbus_verbose ("send_credentials_pending = %d receive_credentials_pending = %d\n",
+                         transport->send_credentials_pending,
+                         transport->receive_credentials_pending);
+          goto out;
+        }
+
+#define TRANSPORT_SIDE(t) ((t)->is_server ? "server" : "client")
+      switch (_dbus_auth_do_work (transport->auth))
+        {
+        case DBUS_AUTH_STATE_WAITING_FOR_INPUT:
+          _dbus_verbose (" %s auth state: waiting for input\n",
+                         TRANSPORT_SIDE (transport));
+          if (!do_reading || !read_data_into_auth (transport, &oom))
+            goto out;
+          break;
+      
+        case DBUS_AUTH_STATE_WAITING_FOR_MEMORY:
+          _dbus_verbose (" %s auth state: waiting for memory\n",
+                         TRANSPORT_SIDE (transport));
+          oom = TRUE;
+          goto out;
+          break;
+      
+        case DBUS_AUTH_STATE_HAVE_BYTES_TO_SEND:
+          _dbus_verbose (" %s auth state: bytes to send\n",
+                         TRANSPORT_SIDE (transport));
+          if (!do_writing || !write_data_from_auth (transport))
+            goto out;
+          break;
+      
+        case DBUS_AUTH_STATE_NEED_DISCONNECT:
+          _dbus_verbose (" %s auth state: need to disconnect\n",
+                         TRANSPORT_SIDE (transport));
+          do_io_error (transport);
+          break;
+      
+        case DBUS_AUTH_STATE_AUTHENTICATED:
+          _dbus_verbose (" %s auth state: authenticated\n",
+                         TRANSPORT_SIDE (transport));
+          break;
+        }
+    }
+
+ out:
+  if (auth_completed)
+    *auth_completed = (orig_auth_state != _dbus_transport_get_is_authenticated (transport));
+  
+  check_read_watch (transport);
+  check_write_watch (transport);
+  _dbus_transport_unref (transport);
+
+  if (oom)
+    return FALSE;
+  else
+    return TRUE;
+}
+
+/* returns false on oom */
+static dbus_bool_t
+do_writing (DBusTransport *transport)
+{
+  int total;
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+  dbus_bool_t oom;
+  
+  /* No messages without authentication! */
+  if (!_dbus_transport_get_is_authenticated (transport))
+    {
+      _dbus_verbose ("Not authenticated, not writing anything\n");
+      return TRUE;
+    }
+
+  if (transport->disconnected)
+    {
+      _dbus_verbose ("Not connected, not writing anything\n");
+      return TRUE;
+    }
+
+#if 1
+  _dbus_verbose ("do_writing(), have_messages = %d, fd = %d\n",
+                 _dbus_connection_has_messages_to_send_unlocked (transport->connection),
+                 socket_transport->fd);
+#endif
+  
+  oom = FALSE;
+  total = 0;
+
+  while (!transport->disconnected &&
+         _dbus_connection_has_messages_to_send_unlocked (transport->connection))
+    {
+      int bytes_written;
+      DBusMessage *message;
+      const DBusString *header;
+      const DBusString *body;
+      int header_len, body_len;
+      int total_bytes_to_write;
+      
+      if (total > socket_transport->max_bytes_written_per_iteration)
+        {
+          _dbus_verbose ("%d bytes exceeds %d bytes written per iteration, returning\n",
+                         total, socket_transport->max_bytes_written_per_iteration);
+          goto out;
+        }
+      
+      message = _dbus_connection_get_message_to_send (transport->connection);
+      _dbus_assert (message != NULL);
+      _dbus_message_lock (message);
+
+#if 0
+      _dbus_verbose ("writing message %p\n", message);
+#endif
+      
+      _dbus_message_get_network_data (message,
+                                      &header, &body);
+
+      header_len = _dbus_string_get_length (header);
+      body_len = _dbus_string_get_length (body);
+
+      if (_dbus_auth_needs_encoding (transport->auth))
+        {
+          if (_dbus_string_get_length (&socket_transport->encoded_outgoing) == 0)
+            {
+              if (!_dbus_auth_encode_data (transport->auth,
+                                           header, &socket_transport->encoded_outgoing))
+                {
+                  oom = TRUE;
+                  goto out;
+                }
+              
+              if (!_dbus_auth_encode_data (transport->auth,
+                                           body, &socket_transport->encoded_outgoing))
+                {
+                  _dbus_string_set_length (&socket_transport->encoded_outgoing, 0);
+                  oom = TRUE;
+                  goto out;
+                }
+            }
+          
+          total_bytes_to_write = _dbus_string_get_length (&socket_transport->encoded_outgoing);
+
+#if 0
+          _dbus_verbose ("encoded message is %d bytes\n",
+                         total_bytes_to_write);
+#endif
+          
+          bytes_written =
+            _dbus_write_socket (socket_transport->fd,
+                                &socket_transport->encoded_outgoing,
+                                socket_transport->message_bytes_written,
+                                total_bytes_to_write - socket_transport->message_bytes_written);
+        }
+      else
+        {
+          total_bytes_to_write = header_len + body_len;
+
+#if 0
+          _dbus_verbose ("message is %d bytes\n",
+                         total_bytes_to_write);          
+#endif
+          
+          if (socket_transport->message_bytes_written < header_len)
+            {
+              bytes_written =
+                _dbus_write_socket_two (socket_transport->fd,
+                                        header,
+                                        socket_transport->message_bytes_written,
+                                        header_len - socket_transport->message_bytes_written,
+                                        body,
+                                        0, body_len);
+            }
+          else
+            {
+              bytes_written =
+                _dbus_write_socket (socket_transport->fd,
+                                    body,
+                                    (socket_transport->message_bytes_written - header_len),
+                                    body_len -
+                                    (socket_transport->message_bytes_written - header_len));
+            }
+        }
+
+      if (bytes_written < 0)
+        {
+          /* EINTR already handled for us */
+          
+          if (errno == EAGAIN ||
+              errno == EWOULDBLOCK)
+            goto out;
+          else
+            {
+              _dbus_verbose ("Error writing to remote app: %s\n",
+                             _dbus_strerror (errno));
+              do_io_error (transport);
+              goto out;
+            }
+        }
+      else
+        {
+          _dbus_verbose (" wrote %d bytes of %d\n", bytes_written,
+                         total_bytes_to_write);
+          
+          total += bytes_written;
+          socket_transport->message_bytes_written += bytes_written;
+
+          _dbus_assert (socket_transport->message_bytes_written <=
+                        total_bytes_to_write);
+          
+          if (socket_transport->message_bytes_written == total_bytes_to_write)
+            {
+              socket_transport->message_bytes_written = 0;
+              _dbus_string_set_length (&socket_transport->encoded_outgoing, 0);
+
+              _dbus_connection_message_sent (transport->connection,
+                                             message);
+            }
+        }
+    }
+
+ out:
+  if (oom)
+    return FALSE;
+  else
+    return TRUE;
+}
+
+/* returns false on out-of-memory */
+static dbus_bool_t
+do_reading (DBusTransport *transport)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+  DBusString *buffer;
+  int bytes_read;
+  int total;
+  dbus_bool_t oom;
+
+  _dbus_verbose ("%s: fd = %d\n", _DBUS_FUNCTION_NAME,
+                 socket_transport->fd);
+  
+  /* No messages without authentication! */
+  if (!_dbus_transport_get_is_authenticated (transport))
+    return TRUE;
+
+  oom = FALSE;
+  
+  total = 0;
+
+ again:
+  
+  /* See if we've exceeded max messages and need to disable reading */
+  check_read_watch (transport);
+  
+  if (total > socket_transport->max_bytes_read_per_iteration)
+    {
+      _dbus_verbose ("%d bytes exceeds %d bytes read per iteration, returning\n",
+                     total, socket_transport->max_bytes_read_per_iteration);
+      goto out;
+    }
+
+  _dbus_assert (socket_transport->read_watch != NULL ||
+                transport->disconnected);
+  
+  if (transport->disconnected)
+    goto out;
+
+  if (!dbus_watch_get_enabled (socket_transport->read_watch))
+    return TRUE;
+  
+  if (_dbus_auth_needs_decoding (transport->auth))
+    {
+      if (_dbus_string_get_length (&socket_transport->encoded_incoming) > 0)
+        bytes_read = _dbus_string_get_length (&socket_transport->encoded_incoming);
+      else
+        bytes_read = _dbus_read_socket (socket_transport->fd,
+                                        &socket_transport->encoded_incoming,
+                                        socket_transport->max_bytes_read_per_iteration);
+
+      _dbus_assert (_dbus_string_get_length (&socket_transport->encoded_incoming) ==
+                    bytes_read);
+      
+      if (bytes_read > 0)
+        {
+          int orig_len;
+          
+          _dbus_message_loader_get_buffer (transport->loader,
+                                           &buffer);
+
+          orig_len = _dbus_string_get_length (buffer);
+          
+          if (!_dbus_auth_decode_data (transport->auth,
+                                       &socket_transport->encoded_incoming,
+                                       buffer))
+            {
+              _dbus_verbose ("Out of memory decoding incoming data\n");
+              oom = TRUE;
+              goto out;
+            }
+
+          _dbus_message_loader_return_buffer (transport->loader,
+                                              buffer,
+                                              _dbus_string_get_length (buffer) - orig_len);
+
+          _dbus_string_set_length (&socket_transport->encoded_incoming, 0);
+        }
+    }
+  else
+    {
+      _dbus_message_loader_get_buffer (transport->loader,
+                                       &buffer);
+      
+      bytes_read = _dbus_read_socket (socket_transport->fd,
+                                      buffer, socket_transport->max_bytes_read_per_iteration);
+      
+      _dbus_message_loader_return_buffer (transport->loader,
+                                          buffer,
+                                          bytes_read < 0 ? 0 : bytes_read);
+    }
+  
+  if (bytes_read < 0)
+    {
+      /* EINTR already handled for us */
+
+      if (errno == ENOMEM)
+        {
+          _dbus_verbose ("Out of memory in read()/do_reading()\n");
+          oom = TRUE;
+          goto out;
+        }
+      else if (errno == EAGAIN ||
+               errno == EWOULDBLOCK)
+        goto out;
+      else
+        {
+          _dbus_verbose ("Error reading from remote app: %s\n",
+                         _dbus_strerror (errno));
+          do_io_error (transport);
+          goto out;
+        }
+    }
+  else if (bytes_read == 0)
+    {
+      _dbus_verbose ("Disconnected from remote app\n");
+      do_io_error (transport);
+      goto out;
+    }
+  else
+    {
+      _dbus_verbose (" read %d bytes\n", bytes_read);
+      
+      total += bytes_read;      
+
+      if (!_dbus_transport_queue_messages (transport))
+        {
+          oom = TRUE;
+          _dbus_verbose (" out of memory when queueing messages we just read in the transport\n");
+          goto out;
+        }
+      
+      /* Try reading more data until we get EAGAIN and return, or
+       * exceed max bytes per iteration.  If in blocking mode of
+       * course we'll block instead of returning.
+       */
+      goto again;
+    }
+
+ out:
+  if (oom)
+    return FALSE;
+  else
+    return TRUE;
+}
+
+static dbus_bool_t
+socket_handle_watch (DBusTransport *transport,
+                   DBusWatch     *watch,
+                   unsigned int   flags)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+
+  _dbus_assert (watch == socket_transport->read_watch ||
+                watch == socket_transport->write_watch);
+  _dbus_assert (watch != NULL);
+  
+  /* Disconnect in case of an error.  In case of hangup do not
+   * disconnect the transport because data can still be in the buffer
+   * and do_reading may need several iteration to read it all (because
+   * of its max_bytes_read_per_iteration limit).  The condition where
+   * flags == HANGUP (without READABLE) probably never happen in fact.
+   */
+  if ((flags & DBUS_WATCH_ERROR) ||
+      ((flags & DBUS_WATCH_HANGUP) && !(flags & DBUS_WATCH_READABLE)))
+    {
+      _dbus_verbose ("Hang up or error on watch\n");
+      _dbus_transport_disconnect (transport);
+      return TRUE;
+    }
+  
+  if (watch == socket_transport->read_watch &&
+      (flags & DBUS_WATCH_READABLE))
+    {
+      dbus_bool_t auth_finished;
+#if 1
+      _dbus_verbose ("handling read watch %p flags = %x\n",
+                     watch, flags);
+#endif
+      if (!do_authentication (transport, TRUE, FALSE, &auth_finished))
+        return FALSE;
+
+      /* We don't want to do a read immediately following
+       * a successful authentication.  This is so we
+       * have a chance to propagate the authentication
+       * state further up.  Specifically, we need to
+       * process any pending data from the auth object.
+       */
+      if (!auth_finished)
+	{
+	  if (!do_reading (transport))
+	    {
+	      _dbus_verbose ("no memory to read\n");
+	      return FALSE;
+	    }
+	}
+      else
+        {
+          _dbus_verbose ("Not reading anything since we just completed the authentication\n");
+        }
+    }
+  else if (watch == socket_transport->write_watch &&
+           (flags & DBUS_WATCH_WRITABLE))
+    {
+#if 1
+      _dbus_verbose ("handling write watch, have_outgoing_messages = %d\n",
+                     _dbus_connection_has_messages_to_send_unlocked (transport->connection));
+#endif
+      if (!do_authentication (transport, FALSE, TRUE, NULL))
+        return FALSE;
+      
+      if (!do_writing (transport))
+        {
+          _dbus_verbose ("no memory to write\n");
+          return FALSE;
+        }
+
+      /* See if we still need the write watch */
+      check_write_watch (transport);
+    }
+#ifdef DBUS_ENABLE_VERBOSE_MODE
+  else
+    {
+      if (watch == socket_transport->read_watch)
+        _dbus_verbose ("asked to handle read watch with non-read condition 0x%x\n",
+                       flags);
+      else if (watch == socket_transport->write_watch)
+        _dbus_verbose ("asked to handle write watch with non-write condition 0x%x\n",
+                       flags);
+      else
+        _dbus_verbose ("asked to handle watch %p on fd %d that we don't recognize\n",
+                       watch, dbus_watch_get_fd (watch));
+    }
+#endif /* DBUS_ENABLE_VERBOSE_MODE */
+
+  return TRUE;
+}
+
+static void
+socket_disconnect (DBusTransport *transport)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+
+  _dbus_verbose ("%s\n", _DBUS_FUNCTION_NAME);
+  
+  free_watches (transport);
+  
+  _dbus_close_socket (socket_transport->fd, NULL);
+  socket_transport->fd = -1;
+}
+
+static dbus_bool_t
+socket_connection_set (DBusTransport *transport)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+
+  _dbus_watch_set_handler (socket_transport->write_watch,
+                           _dbus_connection_handle_watch,
+                           transport->connection, NULL);
+
+  _dbus_watch_set_handler (socket_transport->read_watch,
+                           _dbus_connection_handle_watch,
+                           transport->connection, NULL);
+  
+  if (!_dbus_connection_add_watch_unlocked (transport->connection,
+                                            socket_transport->write_watch))
+    return FALSE;
+
+  if (!_dbus_connection_add_watch_unlocked (transport->connection,
+                                            socket_transport->read_watch))
+    {
+      _dbus_connection_remove_watch_unlocked (transport->connection,
+                                              socket_transport->write_watch);
+      return FALSE;
+    }
+
+  check_read_watch (transport);
+  check_write_watch (transport);
+
+  return TRUE;
+}
+
+/**
+ * @todo We need to have a way to wake up the select sleep if
+ * a new iteration request comes in with a flag (read/write) that
+ * we're not currently serving. Otherwise a call that just reads
+ * could block a write call forever (if there are no incoming
+ * messages).
+ */
+static  void
+socket_do_iteration (DBusTransport *transport,
+                   unsigned int   flags,
+                   int            timeout_milliseconds)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+  DBusPollFD poll_fd;
+  int poll_res;
+  int poll_timeout;
+
+  _dbus_verbose (" iteration flags = %s%s timeout = %d read_watch = %p write_watch = %p fd = %d\n",
+                 flags & DBUS_ITERATION_DO_READING ? "read" : "",
+                 flags & DBUS_ITERATION_DO_WRITING ? "write" : "",
+                 timeout_milliseconds,
+                 socket_transport->read_watch,
+                 socket_transport->write_watch,
+                 socket_transport->fd);
+  
+  /* the passed in DO_READING/DO_WRITING flags indicate whether to
+   * read/write messages, but regardless of those we may need to block
+   * for reading/writing to do auth.  But if we do reading for auth,
+   * we don't want to read any messages yet if not given DO_READING.
+   */
+
+  poll_fd.fd = socket_transport->fd;
+  poll_fd.events = 0;
+  
+  if (_dbus_transport_get_is_authenticated (transport))
+    {
+      /* This is kind of a hack; if we have stuff to write, then try
+       * to avoid the poll. This is probably about a 5% speedup on an
+       * echo client/server.
+       *
+       * If both reading and writing were requested, we want to avoid this
+       * since it could have funky effects:
+       *   - both ends spinning waiting for the other one to read
+       *     data so they can finish writing
+       *   - prioritizing all writing ahead of reading
+       */
+      if ((flags & DBUS_ITERATION_DO_WRITING) &&
+          !(flags & (DBUS_ITERATION_DO_READING | DBUS_ITERATION_BLOCK)) &&
+          !transport->disconnected &&
+          _dbus_connection_has_messages_to_send_unlocked (transport->connection))
+        {
+          do_writing (transport);
+
+          if (transport->disconnected ||
+              !_dbus_connection_has_messages_to_send_unlocked (transport->connection))
+            goto out;
+        }
+
+      /* If we get here, we decided to do the poll() after all */
+      _dbus_assert (socket_transport->read_watch);
+      if (flags & DBUS_ITERATION_DO_READING)
+	poll_fd.events |= _DBUS_POLLIN;
+
+      _dbus_assert (socket_transport->write_watch);
+      if (flags & DBUS_ITERATION_DO_WRITING)
+        poll_fd.events |= _DBUS_POLLOUT;
+    }
+  else
+    {
+      DBusAuthState auth_state;
+      
+      auth_state = _dbus_auth_do_work (transport->auth);
+
+      if (transport->receive_credentials_pending ||
+          auth_state == DBUS_AUTH_STATE_WAITING_FOR_INPUT)
+	poll_fd.events |= _DBUS_POLLIN;
+
+      if (transport->send_credentials_pending ||
+          auth_state == DBUS_AUTH_STATE_HAVE_BYTES_TO_SEND)
+	poll_fd.events |= _DBUS_POLLOUT;
+    }
+
+  if (poll_fd.events)
+    {
+      if (flags & DBUS_ITERATION_BLOCK)
+	poll_timeout = timeout_milliseconds;
+      else
+	poll_timeout = 0;
+
+      /* For blocking selects we drop the connection lock here
+       * to avoid blocking out connection access during a potentially
+       * indefinite blocking call. The io path is still protected
+       * by the io_path_cond condvar, so we won't reenter this.
+       */
+      if (flags & DBUS_ITERATION_BLOCK)
+        {
+          _dbus_verbose ("unlock %s pre poll\n", _DBUS_FUNCTION_NAME);
+          _dbus_connection_unlock (transport->connection);
+        }
+      
+    again:
+      poll_res = _dbus_poll (&poll_fd, 1, poll_timeout);
+
+      if (poll_res < 0 && errno == EINTR)
+	goto again;
+
+      if (flags & DBUS_ITERATION_BLOCK)
+        {
+          _dbus_verbose ("lock %s post poll\n", _DBUS_FUNCTION_NAME);
+          _dbus_connection_lock (transport->connection);
+        }
+      
+      if (poll_res >= 0)
+        {
+          if (poll_res == 0)
+            poll_fd.revents = 0; /* some concern that posix does not guarantee this;
+                                  * valgrind flags it as an error. though it probably
+                                  * is guaranteed on linux at least.
+                                  */
+          
+          if (poll_fd.revents & _DBUS_POLLERR)
+            do_io_error (transport);
+          else
+            {
+              dbus_bool_t need_read = (poll_fd.revents & _DBUS_POLLIN) > 0;
+              dbus_bool_t need_write = (poll_fd.revents & _DBUS_POLLOUT) > 0;
+	      dbus_bool_t authentication_completed;
+
+              _dbus_verbose ("in iteration, need_read=%d need_write=%d\n",
+                             need_read, need_write);
+              do_authentication (transport, need_read, need_write,
+				 &authentication_completed);
+
+	      /* See comment in socket_handle_watch. */
+	      if (authentication_completed)
+                goto out;
+                                 
+              if (need_read && (flags & DBUS_ITERATION_DO_READING))
+                do_reading (transport);
+              if (need_write && (flags & DBUS_ITERATION_DO_WRITING))
+                do_writing (transport);
+            }
+        }
+      else
+        {
+          _dbus_verbose ("Error from _dbus_poll(): %s\n",
+                         _dbus_strerror (errno));
+        }
+    }
+
+
+ out:
+  /* We need to install the write watch only if we did not
+   * successfully write everything. Note we need to be careful that we
+   * don't call check_write_watch *before* do_writing, since it's
+   * inefficient to add the write watch, and we can avoid it most of
+   * the time since we can write immediately.
+   * 
+   * However, we MUST always call check_write_watch(); DBusConnection code
+   * relies on the fact that running an iteration will notice that
+   * messages are pending.
+   */
+  check_write_watch (transport);
+
+  _dbus_verbose (" ... leaving do_iteration()\n");
+}
+
+static void
+socket_live_messages_changed (DBusTransport *transport)
+{
+  /* See if we should look for incoming messages again */
+  check_read_watch (transport);
+}
+
+
+static dbus_bool_t
+socket_get_socket_fd (DBusTransport *transport,
+                      int           *fd_p)
+{
+  DBusTransportSocket *socket_transport = (DBusTransportSocket*) transport;
+  
+  *fd_p = socket_transport->fd;
+  
+  return TRUE;
+}
+
+static const DBusTransportVTable socket_vtable = {
+  socket_finalize,
+  socket_handle_watch,
+  socket_disconnect,
+  socket_connection_set,
+  socket_do_iteration,
+  socket_live_messages_changed,
+  socket_get_socket_fd
+};
+
+/**
+ * Creates a new transport for the given socket file descriptor.  The file
+ * descriptor must be nonblocking (use _dbus_set_fd_nonblocking() to
+ * make it so). This function is shared by various transports that
+ * boil down to a full duplex file descriptor.
+ *
+ * @param fd the file descriptor.
+ * @param server_guid non-#NULL if this transport is on the server side of a connection
+ * @param address the transport's address
+ * @returns the new transport, or #NULL if no memory.
+ */
+DBusTransport*
+_dbus_transport_new_for_socket (int               fd,
+                                const DBusString *server_guid,
+                                const DBusString *address)
+{
+  DBusTransportSocket *socket_transport;
+  
+  socket_transport = dbus_new0 (DBusTransportSocket, 1);
+  if (socket_transport == NULL)
+    return NULL;
+
+  if (!_dbus_string_init (&socket_transport->encoded_outgoing))
+    goto failed_0;
+
+  if (!_dbus_string_init (&socket_transport->encoded_incoming))
+    goto failed_1;
+  
+  socket_transport->write_watch = _dbus_watch_new (fd,
+                                                 DBUS_WATCH_WRITABLE,
+                                                 FALSE,
+                                                 NULL, NULL, NULL);
+  if (socket_transport->write_watch == NULL)
+    goto failed_2;
+  
+  socket_transport->read_watch = _dbus_watch_new (fd,
+                                                DBUS_WATCH_READABLE,
+                                                FALSE,
+                                                NULL, NULL, NULL);
+  if (socket_transport->read_watch == NULL)
+    goto failed_3;
+  
+  if (!_dbus_transport_init_base (&socket_transport->base,
+                                  &socket_vtable,
+                                  server_guid, address))
+    goto failed_4;
+  
+  socket_transport->fd = fd;
+  socket_transport->message_bytes_written = 0;
+  
+  /* These values should probably be tunable or something. */     
+  socket_transport->max_bytes_read_per_iteration = 2048;
+  socket_transport->max_bytes_written_per_iteration = 2048;
+  
+  return (DBusTransport*) socket_transport;
+
+ failed_4:
+  _dbus_watch_unref (socket_transport->read_watch);
+ failed_3:
+  _dbus_watch_unref (socket_transport->write_watch);
+ failed_2:
+  _dbus_string_free (&socket_transport->encoded_incoming);
+ failed_1:
+  _dbus_string_free (&socket_transport->encoded_outgoing);
+ failed_0:
+  dbus_free (socket_transport);
+  return NULL;
+}
+
+/**
+ * Creates a new transport for the given hostname and port.
+ *
+ * @param host the host to connect to
+ * @param port the port to connect to
+ * @param error location to store reason for failure.
+ * @returns a new transport, or #NULL on failure.
+ */
+DBusTransport*
+_dbus_transport_new_for_tcp_socket (const char     *host,
+                                    dbus_int32_t    port,
+                                    DBusError      *error)
+{
+  int fd;
+  DBusTransport *transport;
+  DBusString address;
+  
+  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
+
+  if (!_dbus_string_init (&address))
+    {
+      dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
+      return NULL;
+    }
+  
+  if (!_dbus_string_append (&address, "tcp:"))
+    goto error;
+
+  if (host != NULL && 
+       (!_dbus_string_append (&address, "host=") ||
+        !_dbus_string_append (&address, host)))
+    goto error;
+
+  if (!_dbus_string_append (&address, ",port=") ||
+      !_dbus_string_append_int (&address, port))
+    goto error;
+
+  fd = _dbus_connect_tcp_socket (host, port, error);
+  if (fd < 0)
+    {
+      _DBUS_ASSERT_ERROR_IS_SET (error);
+      _dbus_string_free (&address);
+      return NULL;
+    }
+
+  _dbus_fd_set_close_on_exec (fd);
+  
+  _dbus_verbose ("Successfully connected to tcp socket %s:%d\n",
+                 host, port);
+  
+  transport = _dbus_transport_new_for_socket (fd, NULL, &address);
+  if (transport == NULL)
+    {
+      dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
+      _dbus_close_socket (fd, NULL);
+      _dbus_string_free (&address);
+      fd = -1;
+    }
+
+  _dbus_string_free (&address);
+  
+  return transport;
+
+error:
+  _dbus_string_free (&address);
+  dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
+  return NULL;
+}
+
+/** @} */
+