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glib/gio/gunixconnection.c
Philip Withnall 2be7859f10 docs: Move the GUnixConnection SECTION 
Move it to the struct docs.

Signed-off-by: Philip Withnall <philip@tecnocode.co.uk>

Helps: #3037
2023-11-02 16:30:23 +00:00

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/* 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
/**
* GUnixConnection:
*
* This is the subclass of [class@Gio.SocketConnection] 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
*/
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);
}
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