/* GIO - GLib Input, Output and Streaming Library

 *

 * Copyright © 2009 Codethink Limited

 *

 * SPDX-License-Identifier: LGPL-2.1-or-later

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * See the included COPYING file for more information.

 *

 * Authors: Ryan Lortie <desrt@desrt.ca>

 */

#include "config.h"

#include "gunixconnection.h"

#include "gnetworking.h"

#include "gsocket.h"

#include "gsocketcontrolmessage.h"

#include "gunixcredentialsmessage.h"

#include "gunixfdmessage.h"

#include "glibintl.h"

#include <errno.h>

#include <string.h>

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

/**

 * SECTION:gunixconnection

 * @title: GUnixConnection

 * @short_description: A UNIX domain GSocketConnection

 * @include: gio/gunixconnection.h

 * @see_also: #GSocketConnection.

 *

 * This is the subclass of #GSocketConnection that is created

 * for UNIX domain sockets.

 *

 * It contains functions to do some of the UNIX socket specific

 * functionality like passing file descriptors.

 *

 * Since GLib 2.72, #GUnixConnection is available on all platforms. It requires

 * underlying system support (such as Windows 10 with `AF_UNIX`) at run time.

 *

 * Before GLib 2.72, `<gio/gunixconnection.h>` belonged to the UNIX-specific GIO

 * interfaces, thus you had to use the `gio-unix-2.0.pc` pkg-config file when

 * using it. This is no longer necessary since GLib 2.72.

 *

 * Since: 2.22

 */

/**

 * GUnixConnection:

 *

 * #GUnixConnection is an opaque data structure and can only be accessed

 * using the following functions.

 **/

G_DEFINE_TYPE_WITH_CODE (GUnixConnection, g_unix_connection,

       G_TYPE_SOCKET_CONNECTION,

  g_socket_connection_factory_register_type (g_define_type_id,

               G_SOCKET_FAMILY_UNIX,

               G_SOCKET_TYPE_STREAM,

               G_SOCKET_PROTOCOL_DEFAULT);

       );

/**

 * g_unix_connection_send_fd:

 * @connection: a #GUnixConnection

 * @fd: a file descriptor

 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.

 * @error: (nullable): #GError for error reporting, or %NULL to ignore.

 *

 * Passes a file descriptor to the receiving side of the

 * connection. The receiving end has to call g_unix_connection_receive_fd()

 * to accept the file descriptor.

 *

 * As well as sending the fd this also writes a single byte to the

 * stream, as this is required for fd passing to work on some

 * implementations.

 *

 * Returns: a %TRUE on success, %NULL on error.

 *

 * Since: 2.22

 */

gboolean

g_unix_connection_send_fd (GUnixConnection  *connection,

                           gint              fd,

                           GCancellable     *cancellable,

                           GError          **error)

{

#ifdef G_OS_UNIX

  GSocketControlMessage *scm;

  GSocket *socket;

  g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), FALSE);

  g_return_val_if_fail (fd >= 0, FALSE);

  scm = g_unix_fd_message_new ();

  if (!g_unix_fd_message_append_fd (G_UNIX_FD_MESSAGE (scm), fd, error))

    {

      g_object_unref (scm);

      return FALSE;

    }

  g_object_get (connection, "socket", &socket, NULL);

  if (g_socket_send_message (socket, NULL, NULL, 0, &scm, 1, 0, cancellable, error) != 1)

    /* XXX could it 'fail' with zero? */

    {

      g_object_unref (socket);

      g_object_unref (scm);

      return FALSE;

    }

  g_object_unref (socket);

  g_object_unref (scm);

  return TRUE;

#else

  g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,

                       _("Sending FD is not supported"));

  return FALSE;

#endif

}

/**

 * g_unix_connection_receive_fd:

 * @connection: a #GUnixConnection

 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore

 * @error: (nullable): #GError for error reporting, or %NULL to ignore

 *

 * Receives a file descriptor from the sending end of the connection.

 * The sending end has to call g_unix_connection_send_fd() for this

 * to work.

 *

 * As well as reading the fd this also reads a single byte from the

 * stream, as this is required for fd passing to work on some

 * implementations.

 *

 * Returns: a file descriptor on success, -1 on error.

 *

 * Since: 2.22

 **/

gint

g_unix_connection_receive_fd (GUnixConnection  *connection,

                              GCancellable     *cancellable,

                              GError          **error)

{

#ifdef G_OS_UNIX

  GSocketControlMessage **scms;

  gint *fds, nfd, fd, nscm;

  GUnixFDMessage *fdmsg;

  GSocket *socket;

  g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), -1);

  g_object_get (connection, "socket", &socket, NULL);

  if (g_socket_receive_message (socket, NULL, NULL, 0,

                                &scms, &nscm, NULL, cancellable, error) != 1)

    /* XXX it _could_ 'fail' with zero. */

    {

      g_object_unref (socket);

      return -1;

    }

  g_object_unref (socket);

  if (nscm != 1)

    {

      gint i;

      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,

                   g_dngettext (NULL,

                                "Expecting 1 control message, got %d",

                                "Expecting 1 control message, got %d",

                                nscm),

                   nscm);

      for (i = 0; i < nscm; i++)

        g_object_unref (scms[i]);

      g_free (scms);

      return -1;

    }

  if (!G_IS_UNIX_FD_MESSAGE (scms[0]))

    {

      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,

         _("Unexpected type of ancillary data"));

      g_object_unref (scms[0]);

      g_free (scms);

      return -1;

    }

  fdmsg = G_UNIX_FD_MESSAGE (scms[0]);

  g_free (scms);

  fds = g_unix_fd_message_steal_fds (fdmsg, &nfd);

  g_object_unref (fdmsg);

  if (nfd != 1)

    {

      gint i;

      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,

                   g_dngettext (NULL,

                                "Expecting one fd, but got %d\n",

                                "Expecting one fd, but got %d\n",

                                nfd),

                   nfd);

      for (i = 0; i < nfd; i++)

        close (fds[i]);

      g_free (fds);

      return -1;

    }

  fd = *fds;

  g_free (fds);

  if (fd < 0)

    {

      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,

                           _("Received invalid fd"));

      fd = -1;

    }

  return fd;

#else

  g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,

                       _("Receiving FD is not supported"));

  return -1;

#endif

}

static void

g_unix_connection_init (GUnixConnection *connection)

{

}

static void

g_unix_connection_class_init (GUnixConnectionClass *class)

{

}

/* TODO: Other stuff we might want to add are:

void                    g_unix_connection_send_fd_async                 (GUnixConnection      *connection,

                                                                         gint                  fd,

                                                                         gboolean              close,

                                                                         gint                  io_priority,

                                                                         GAsyncReadyCallback   callback,

                                                                         gpointer              user_data);

gboolean                g_unix_connection_send_fd_finish                (GUnixConnection      *connection,

                                                                         GError              **error);

gboolean                g_unix_connection_send_fds                      (GUnixConnection      *connection,

                                                                         gint                 *fds,

                                                                         gint                  nfds,

                                                                         GError              **error);

void                    g_unix_connection_send_fds_async                (GUnixConnection      *connection,

                                                                         gint                 *fds,

                                                                         gint                  nfds,

                                                                         gint                  io_priority,

                                                                         GAsyncReadyCallback   callback,

                                                                         gpointer              user_data);

gboolean                g_unix_connection_send_fds_finish               (GUnixConnection      *connection,

                                                                         GError              **error);

void                    g_unix_connection_receive_fd_async              (GUnixConnection      *connection,

                                                                         gint                  io_priority,

                                                                         GAsyncReadyCallback   callback,

                                                                         gpointer              user_data);

gint                    g_unix_connection_receive_fd_finish             (GUnixConnection      *connection,

                                                                         GError              **error);

gboolean                g_unix_connection_send_fake_credentials         (GUnixConnection      *connection,

                                                                         guint64               pid,

                                                                         guint64               uid,

                                                                         guint64               gid,

                                                                         GError              **error);

void                    g_unix_connection_send_fake_credentials_async   (GUnixConnection      *connection,

                                                                         guint64               pid,

                                                                         guint64               uid,

                                                                         guint64               gid,

                                                                         gint                  io_priority,

                                                                         GAsyncReadyCallback   callback,

                                                                         gpointer              user_data);

gboolean                g_unix_connection_send_fake_credentials_finish  (GUnixConnection      *connection,

                                                                         GError              **error);

gboolean                g_unix_connection_create_pair                   (GUnixConnection     **one,

                                                                         GUnixConnection     **two,

                                                                         GError              **error);

*/

/**

 * g_unix_connection_send_credentials:

 * @connection: A #GUnixConnection.

 * @cancellable: (nullable): A #GCancellable or %NULL.

 * @error: Return location for error or %NULL.

 *

 * Passes the credentials of the current user the receiving side

 * of the connection. The receiving end has to call

 * g_unix_connection_receive_credentials() (or similar) to accept the

 * credentials.

 *

 * As well as sending the credentials this also writes a single NUL

 * byte to the stream, as this is required for credentials passing to

 * work on some implementations.

 *

 * This method can be expected to be available on the following platforms:

 *

 * - Linux since GLib 2.26

 * - FreeBSD since GLib 2.26

 * - GNU/kFreeBSD since GLib 2.36

 * - Solaris, Illumos and OpenSolaris since GLib 2.40

 * - GNU/Hurd since GLib 2.40

 *

 * Other ways to exchange credentials with a foreign peer includes the

 * #GUnixCredentialsMessage type and g_socket_get_credentials() function.

 *

 * Returns: %TRUE on success, %FALSE if @error is set.

 *

 * Since: 2.26

 */

gboolean

g_unix_connection_send_credentials (GUnixConnection      *connection,

                                    GCancellable         *cancellable,

                                    GError              **error)

{

  GCredentials *credentials;

  GSocketControlMessage *scm;

  GSocket *socket;

  gboolean ret;

  GOutputVector vector;

  guchar nul_byte[1] = {'\0'};

  gint num_messages;

  g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), FALSE);

  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  ret = FALSE;

  credentials = g_credentials_new ();

  vector.buffer = &nul_byte;

  vector.size = 1;

  if (g_unix_credentials_message_is_supported ())

    {

      scm = g_unix_credentials_message_new_with_credentials (credentials);

      num_messages = 1;

    }

  else

    {

      scm = NULL;

      num_messages = 0;

    }

  g_object_get (connection, "socket", &socket, NULL);

  if (g_socket_send_message (socket,

                             NULL, /* address */

                             &vector,

                             1,

                             &scm,

                             num_messages,

                             G_SOCKET_MSG_NONE,

                             cancellable,

                             error) != 1)

    {

      g_prefix_error (error, _("Error sending credentials: "));

      goto out;

    }

  ret = TRUE;

 out:

  g_object_unref (socket);

  if (scm != NULL)

    g_object_unref (scm);

  g_object_unref (credentials);

  return ret;

}

static void

send_credentials_async_thread (GTask         *task,

             gpointer       source_object,

             gpointer       task_data,

             GCancellable  *cancellable)

{

  GError *error = NULL;

  if (g_unix_connection_send_credentials (G_UNIX_CONNECTION (source_object),

            cancellable,

            &error))

    g_task_return_boolean (task, TRUE);

  else

    g_task_return_error (task, error);

  g_object_unref (task);

}

/**

 * g_unix_connection_send_credentials_async:

 * @connection: A #GUnixConnection.

 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.

 * @callback: (scope async): a #GAsyncReadyCallback

 *   to call when the request is satisfied

 * @user_data: the data to pass to callback function

 *

 * Asynchronously send credentials.

 *

 * For more details, see g_unix_connection_send_credentials() which is

 * the synchronous version of this call.

 *

 * When the operation is finished, @callback will be called. You can then call

 * g_unix_connection_send_credentials_finish() to get the result of the operation.

 *

 * Since: 2.32

 **/

void

g_unix_connection_send_credentials_async (GUnixConnection      *connection,

                                          GCancellable         *cancellable,

                                          GAsyncReadyCallback   callback,

                                          gpointer              user_data)

{

  GTask *task;

  task = g_task_new (connection, cancellable, callback, user_data);

  g_task_set_source_tag (task, g_unix_connection_send_credentials_async);

  g_task_run_in_thread (task, send_credentials_async_thread);

}

/**

 * g_unix_connection_send_credentials_finish:

 * @connection: A #GUnixConnection.

 * @result: a #GAsyncResult.

 * @error: a #GError, or %NULL

 *

 * Finishes an asynchronous send credentials operation started with

 * g_unix_connection_send_credentials_async().

 *

 * Returns: %TRUE if the operation was successful, otherwise %FALSE.

 *

 * Since: 2.32

 **/

gboolean

g_unix_connection_send_credentials_finish (GUnixConnection *connection,

                                           GAsyncResult    *result,

                                           GError         **error)

{

  g_return_val_if_fail (g_task_is_valid (result, connection), FALSE);

  return g_task_propagate_boolean (G_TASK (result), error);

}

/**

 * g_unix_connection_receive_credentials:

 * @connection: A #GUnixConnection.

 * @cancellable: (nullable): A #GCancellable or %NULL.

 * @error: Return location for error or %NULL.

 *

 * Receives credentials from the sending end of the connection.  The

 * sending end has to call g_unix_connection_send_credentials() (or

 * similar) for this to work.

 *

 * As well as reading the credentials this also reads (and discards) a

 * single byte from the stream, as this is required for credentials

 * passing to work on some implementations.

 *

 * This method can be expected to be available on the following platforms:

 *

 * - Linux since GLib 2.26

 * - FreeBSD since GLib 2.26

 * - GNU/kFreeBSD since GLib 2.36

 * - Solaris, Illumos and OpenSolaris since GLib 2.40

 * - GNU/Hurd since GLib 2.40

 *

 * Other ways to exchange credentials with a foreign peer includes the

 * #GUnixCredentialsMessage type and g_socket_get_credentials() function.

 *

 * Returns: (transfer full): Received credentials on success (free with

 * g_object_unref()), %NULL if @error is set.

 *

 * Since: 2.26

 */

GCredentials *

g_unix_connection_receive_credentials (GUnixConnection      *connection,

                                       GCancellable         *cancellable,

                                       GError              **error)

{

  GCredentials *ret;

  GSocketControlMessage **scms;

  gint nscm;

  GSocket *socket;

  gint n;

  gssize num_bytes_read;

#ifdef __linux__

  gboolean turn_off_so_passcreds;

#endif

  g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), NULL);

  g_return_val_if_fail (error == NULL || *error == NULL, NULL);

  ret = NULL;

  scms = NULL;

  g_object_get (connection, "socket", &socket, NULL);

  /* On Linux, we need to turn on SO_PASSCRED if it isn't enabled

   * already. We also need to turn it off when we're done.  See

   * #617483 for more discussion.

   */

#ifdef __linux__

  {

    gint opt_val;

    turn_off_so_passcreds = FALSE;

    opt_val = 0;

    if (!g_socket_get_option (socket,

            SOL_SOCKET,

            SO_PASSCRED,

            &opt_val,

            NULL))

      {

        int errsv = errno;

        g_set_error (error,

                     G_IO_ERROR,

                     g_io_error_from_errno (errsv),

                     _("Error checking if SO_PASSCRED is enabled for socket: %s"),

                     g_strerror (errsv));

        goto out;

      }

    if (opt_val == 0)

      {

        if (!g_socket_set_option (socket,

          SOL_SOCKET,

          SO_PASSCRED,

          TRUE,

          NULL))

          {

            int errsv = errno;

            g_set_error (error,

                         G_IO_ERROR,

                         g_io_error_from_errno (errsv),

                         _("Error enabling SO_PASSCRED: %s"),

                         g_strerror (errsv));

            goto out;

          }

        turn_off_so_passcreds = TRUE;

      }

  }

#endif

  g_type_ensure (G_TYPE_UNIX_CREDENTIALS_MESSAGE);

  num_bytes_read = g_socket_receive_message (socket,

                                             NULL, /* GSocketAddress **address */

                                             NULL,

                                             0,

                                             &scms,

                                             &nscm,

                                             NULL,

                                             cancellable,

                                             error);

  if (num_bytes_read != 1)

    {

      /* Handle situation where g_socket_receive_message() returns

       * 0 bytes and not setting @error

       */

      if (num_bytes_read == 0 && error != NULL && *error == NULL)

        {

          g_set_error_literal (error,

                               G_IO_ERROR,

                               G_IO_ERROR_FAILED,

                               _("Expecting to read a single byte for receiving credentials but read zero bytes"));

        }

      goto out;

    }

  if (g_unix_credentials_message_is_supported () &&

      /* Fall back on get_credentials if the other side didn't send the credentials */

      nscm > 0)

    {

      if (nscm != 1)

        {

          g_set_error (error,

                       G_IO_ERROR,

                       G_IO_ERROR_FAILED,

                       g_dngettext (NULL,

                                    "Expecting 1 control message, got %d",

                                    "Expecting 1 control message, got %d",

                                    nscm),

                       nscm);

          goto out;

        }

      if (!G_IS_UNIX_CREDENTIALS_MESSAGE (scms[0]))

        {

          g_set_error_literal (error,

                               G_IO_ERROR,

                               G_IO_ERROR_FAILED,

                               _("Unexpected type of ancillary data"));

          goto out;

        }

      ret = g_unix_credentials_message_get_credentials (G_UNIX_CREDENTIALS_MESSAGE (scms[0]));

      g_object_ref (ret);

    }

  else

    {

      if (nscm != 0)

        {

          g_set_error (error,

                       G_IO_ERROR,

                       G_IO_ERROR_FAILED,

                       _("Not expecting control message, but got %d"),

                       nscm);

          goto out;

        }

      else

        {

          ret = g_socket_get_credentials (socket, error);

        }

    }

 out:

#ifdef __linux__

  if (turn_off_so_passcreds)

    {

      if (!g_socket_set_option (socket,

        SOL_SOCKET,

        SO_PASSCRED,

        FALSE,

        NULL))

        {

          int errsv = errno;

          g_set_error (error,

                       G_IO_ERROR,

                       g_io_error_from_errno (errsv),

                       _("Error while disabling SO_PASSCRED: %s"),

                       g_strerror (errsv));

          goto out;

        }

    }

#endif

  if (scms != NULL)

    {

      for (n = 0; n < nscm; n++)

        g_object_unref (scms[n]);

      g_free (scms);

    }

  g_object_unref (socket);

  return ret;

}

static void

receive_credentials_async_thread (GTask         *task,

          gpointer       source_object,

          gpointer       task_data,

          GCancellable  *cancellable)

{

  GCredentials *creds;

  GError *error = NULL;

  creds = g_unix_connection_receive_credentials (G_UNIX_CONNECTION (source_object),

                                                 cancellable,

                                                 &error);

  if (creds)

    g_task_return_pointer (task, creds, g_object_unref);

  else

    g_task_return_error (task, error);

  g_object_unref (task);

}

/**

 * g_unix_connection_receive_credentials_async:

 * @connection: A #GUnixConnection.

 * @cancellable: (nullable): optional #GCancellable object, %NULL to ignore.

 * @callback: (scope async): a #GAsyncReadyCallback

 *   to call when the request is satisfied

 * @user_data: the data to pass to callback function

 *

 * Asynchronously receive credentials.

 *

 * For more details, see g_unix_connection_receive_credentials() which is

 * the synchronous version of this call.

 *

 * When the operation is finished, @callback will be called. You can then call

 * g_unix_connection_receive_credentials_finish() to get the result of the operation.

 *

 * Since: 2.32

 **/

void

g_unix_connection_receive_credentials_async (GUnixConnection      *connection,

                                              GCancellable         *cancellable,

                                              GAsyncReadyCallback   callback,

                                              gpointer              user_data)

{

  GTask *task;

  task = g_task_new (connection, cancellable, callback, user_data);

  g_task_set_source_tag (task, g_unix_connection_receive_credentials_async);

  g_task_run_in_thread (task, receive_credentials_async_thread);

}

/**

 * g_unix_connection_receive_credentials_finish:

 * @connection: A #GUnixConnection.

 * @result: a #GAsyncResult.

 * @error: a #GError, or %NULL

 *

 * Finishes an asynchronous receive credentials operation started with

 * g_unix_connection_receive_credentials_async().

 *

 * Returns: (transfer full): a #GCredentials, or %NULL on error.

 *     Free the returned object with g_object_unref().

 *

 * Since: 2.32

 **/

GCredentials *

g_unix_connection_receive_credentials_finish (GUnixConnection *connection,

                                              GAsyncResult    *result,

                                              GError         **error)

{

  g_return_val_if_fail (g_task_is_valid (result, connection), NULL);

  return g_task_propagate_pointer (G_TASK (result), error);

}