/* GIO - GLib Input, Output and Streaming Library

 *

 * Copyright 2011 Red Hat, Inc.

 *

 * 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.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General

 * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

#include "config.h"

#include <errno.h>

#include <string.h>

#include <unistd.h>

#include "gnetworkmonitornetlink.h"

#include "gcredentials.h"

#include "ginetaddressmask.h"

#include "ginitable.h"

#include "giomodule-priv.h"

#include "glibintl.h"

#include "glib/gstdio.h"

#include "gnetworkingprivate.h"

#include "gnetworkmonitor.h"

#include "gsocket.h"

#include "gunixcredentialsmessage.h"

/* must come at the end to pick system includes from

 * gnetworkingprivate.h */

#ifdef HAVE_LINUX_NETLINK_H

#include <linux/netlink.h>

#include <linux/rtnetlink.h>

#endif

#if defined(HAVE_NETLINK_NETLINK_H) && defined(HAVE_NETLINK_NETLINK_ROUTE_H)

#include <netlink/netlink.h>

#include <netlink/netlink_route.h>

#endif

static GInitableIface *initable_parent_iface;

static void g_network_monitor_netlink_iface_init (GNetworkMonitorInterface *iface);

static void g_network_monitor_netlink_initable_iface_init (GInitableIface *iface);

struct _GNetworkMonitorNetlinkPrivate

{

  GSocket *sock;

  GSource *source, *dump_source;

  GMainContext *context;

  GPtrArray *dump_networks;

};

static gboolean read_netlink_messages (GNetworkMonitorNetlink  *nl,

                                       GError                 **error);

static gboolean read_netlink_messages_callback (GSocket             *socket,

                                                GIOCondition         condition,

                                                gpointer             user_data);

static gboolean request_dump (GNetworkMonitorNetlink  *nl,

                              GError                 **error);

#define g_network_monitor_netlink_get_type _g_network_monitor_netlink_get_type

G_DEFINE_TYPE_WITH_CODE (GNetworkMonitorNetlink, g_network_monitor_netlink, G_TYPE_NETWORK_MONITOR_BASE,

                         G_ADD_PRIVATE (GNetworkMonitorNetlink)

                         G_IMPLEMENT_INTERFACE (G_TYPE_NETWORK_MONITOR,

                                                g_network_monitor_netlink_iface_init)

                         G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,

                                                g_network_monitor_netlink_initable_iface_init)

                         _g_io_modules_ensure_extension_points_registered ();

                         g_io_extension_point_implement (G_NETWORK_MONITOR_EXTENSION_POINT_NAME,

                                                         g_define_type_id,

                                                         "netlink",

                                                         20))

static void

g_network_monitor_netlink_init (GNetworkMonitorNetlink *nl)

{

  nl->priv = g_network_monitor_netlink_get_instance_private (nl);

}

static gboolean

g_network_monitor_netlink_initable_init (GInitable     *initable,

                                         GCancellable  *cancellable,

                                         GError       **error)

{

  GNetworkMonitorNetlink *nl = G_NETWORK_MONITOR_NETLINK (initable);

  gint sockfd;

  struct sockaddr_nl snl;

  /* We create the socket the old-school way because sockaddr_netlink

   * can't be represented as a GSocketAddress

   */

  sockfd = g_socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE, NULL);

  if (sockfd == -1)

    {

      int errsv = errno;

      g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv),

                   _("Could not create network monitor: %s"),

                   g_strerror (errsv));

      return FALSE;

    }

  snl.nl_family = AF_NETLINK;

  snl.nl_pid = snl.nl_pad = 0;

  snl.nl_groups = RTMGRP_IPV4_ROUTE | RTMGRP_IPV6_ROUTE;

  if (bind (sockfd, (struct sockaddr *)&snl, sizeof (snl)) != 0)

    {

      int errsv = errno;

      g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv),

                   _("Could not create network monitor: %s"),

                   g_strerror (errsv));

      (void) g_close (sockfd, NULL);

      return FALSE;

    }

  nl->priv->sock = g_socket_new_from_fd (sockfd, error);

  if (!nl->priv->sock)

    {

      g_prefix_error (error, "%s", _("Could not create network monitor: "));

      (void) g_close (sockfd, NULL);

      return FALSE;

    }

#ifdef SO_PASSCRED

  if (!g_socket_set_option (nl->priv->sock, SOL_SOCKET, SO_PASSCRED,

          TRUE, NULL))

    {

      int errsv = errno;

      g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errsv),

                   _("Could not create network monitor: %s"),

                   g_strerror (errsv));

      return FALSE;

    }

#endif

  /* Request the current state */

  if (!request_dump (nl, error))

    return FALSE;

  /* And read responses; since we haven't yet marked the socket

   * non-blocking, each call will block until a message is received.

   */

  while (nl->priv->dump_networks)

    {

      GError *local_error = NULL;

      if (!read_netlink_messages (nl, &local_error))

        {

          g_warning ("%s", local_error->message);

          g_clear_error (&local_error);

          break;

        }

    }

  g_socket_set_blocking (nl->priv->sock, FALSE);

  nl->priv->context = g_main_context_ref_thread_default ();

  nl->priv->source = g_socket_create_source (nl->priv->sock, G_IO_IN, NULL);

  g_source_set_callback (nl->priv->source,

                         (GSourceFunc) read_netlink_messages_callback, nl, NULL);

  g_source_attach (nl->priv->source, nl->priv->context);

  return initable_parent_iface->init (initable, cancellable, error);

}

static gboolean

request_dump (GNetworkMonitorNetlink  *nl,

              GError                 **error)

{

  struct nlmsghdr *n;

  struct rtgenmsg *gen;

  gchar buf[NLMSG_SPACE (sizeof (*gen))];

  memset (buf, 0, sizeof (buf));

  n = (struct nlmsghdr*) buf;

  n->nlmsg_len = NLMSG_LENGTH (sizeof (*gen));

  n->nlmsg_type = RTM_GETROUTE;

  n->nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;

  n->nlmsg_pid = 0;

  gen = NLMSG_DATA (n);

  gen->rtgen_family = AF_UNSPEC;

  if (g_socket_send (nl->priv->sock, buf, sizeof (buf),

                     NULL, error) < 0)

    {

      g_prefix_error (error, "%s", _("Could not get network status: "));

      return FALSE;

    }

  nl->priv->dump_networks = g_ptr_array_new_with_free_func (g_object_unref);

  return TRUE;

}

static gboolean

timeout_request_dump (gpointer user_data)

{

  GNetworkMonitorNetlink *nl = user_data;

  g_source_destroy (nl->priv->dump_source);

  g_source_unref (nl->priv->dump_source);

  nl->priv->dump_source = NULL;

  request_dump (nl, NULL);

  return FALSE;

}

static void

queue_request_dump (GNetworkMonitorNetlink *nl)

{

  if (nl->priv->dump_networks)

    return;

  if (nl->priv->dump_source)

    {

      g_source_destroy (nl->priv->dump_source);

      g_source_unref (nl->priv->dump_source);

    }

  nl->priv->dump_source = g_timeout_source_new_seconds (1);

  g_source_set_callback (nl->priv->dump_source,

                         (GSourceFunc) timeout_request_dump, nl, NULL);

  g_source_attach (nl->priv->dump_source, nl->priv->context);

}

static GInetAddressMask *

create_inet_address_mask (GSocketFamily  family,

                          const guint8  *dest,

                          gsize          dest_len)

{

  GInetAddress *dest_addr;

  GInetAddressMask *network;

  if (dest)

    dest_addr = g_inet_address_new_from_bytes (dest, family);

  else

    dest_addr = g_inet_address_new_any (family);

  network = g_inet_address_mask_new (dest_addr, dest_len, NULL);

  g_object_unref (dest_addr);

  return network;

}

static void

add_network (GNetworkMonitorNetlink *nl,

             GSocketFamily           family,

             const guint8           *dest,

             gsize                   dest_len)

{

  GInetAddressMask *network = create_inet_address_mask (family, dest, dest_len);

  g_return_if_fail (network != NULL);

  if (nl->priv->dump_networks)

    g_ptr_array_add (nl->priv->dump_networks, g_object_ref (network));

  else

    g_network_monitor_base_add_network (G_NETWORK_MONITOR_BASE (nl), network);

  g_object_unref (network);

}

static void

remove_network (GNetworkMonitorNetlink *nl,

                GSocketFamily           family,

                const guint8           *dest,

                gsize                   dest_len)

{

  GInetAddressMask *network = create_inet_address_mask (family, dest, dest_len);

  g_return_if_fail (network != NULL);

  if (nl->priv->dump_networks)

    {

      GInetAddressMask **dump_networks = (GInetAddressMask **)nl->priv->dump_networks->pdata;

      guint i;

      for (i = 0; i < nl->priv->dump_networks->len; i++)

        {

          if (g_inet_address_mask_equal (network, dump_networks[i]))

            g_ptr_array_remove_index_fast (nl->priv->dump_networks, i--);

        }

    }

  else

    {

      g_network_monitor_base_remove_network (G_NETWORK_MONITOR_BASE (nl), network);

    }

  g_object_unref (network);

}

static void

finish_dump (GNetworkMonitorNetlink *nl)

{

  g_network_monitor_base_set_networks (G_NETWORK_MONITOR_BASE (nl),

                                       (GInetAddressMask **)nl->priv->dump_networks->pdata,

                                       nl->priv->dump_networks->len);

  g_ptr_array_free (nl->priv->dump_networks, TRUE);

  nl->priv->dump_networks = NULL;

}

static gboolean

read_netlink_messages (GNetworkMonitorNetlink  *nl,

                       GError                 **error)

{

  GInputVector iv;

  gssize len;

  gint flags;

  GError *local_error = NULL;

  GSocketAddress *addr = NULL;

  struct nlmsghdr *msg;

  struct rtmsg *rtmsg;

  struct rtattr *attr;

  struct sockaddr_nl source_sockaddr;

  gsize attrlen;

  guint8 *dest, *gateway, *oif;

  iv.buffer = NULL;

  iv.size = 0;

  flags = MSG_PEEK | MSG_TRUNC;

  len = g_socket_receive_message (nl->priv->sock, NULL, &iv, 1,

                                  NULL, NULL, &flags, NULL, &local_error);

  if (len < 0)

    goto done;

  iv.buffer = g_malloc (len);

  iv.size = len;

  len = g_socket_receive_message (nl->priv->sock, &addr, &iv, 1,

                                  NULL, NULL, NULL, NULL, &local_error);

  if (len < 0)

    goto done;

  if (!g_socket_address_to_native (addr, &source_sockaddr, sizeof (source_sockaddr), &local_error))

    goto done;

  /* If the sender port id is 0 (not fakeable) then the message is from the kernel */

  if (source_sockaddr.nl_pid != 0)

    goto done;

  msg = (struct nlmsghdr *) iv.buffer;

  for (; len > 0; msg = NLMSG_NEXT (msg, len))

    {

      if (!NLMSG_OK (msg, (size_t) len))

        {

          g_set_error_literal (&local_error,

                               G_IO_ERROR,

                               G_IO_ERROR_PARTIAL_INPUT,

                               "netlink message was truncated; shouldn't happen...");

          goto done;

        }

      switch (msg->nlmsg_type)

        {

        case RTM_NEWROUTE:

        case RTM_DELROUTE:

          rtmsg = NLMSG_DATA (msg);

          if (rtmsg->rtm_family != AF_INET && rtmsg->rtm_family != AF_INET6)

            continue;

          if (rtmsg->rtm_type == RTN_UNREACHABLE)

            continue;

          attrlen = NLMSG_PAYLOAD (msg, sizeof (struct rtmsg));

          attr = RTM_RTA (rtmsg);

          dest = gateway = oif = NULL;

          while (RTA_OK (attr, attrlen))

            {

              if (attr->rta_type == RTA_DST)

                dest = RTA_DATA (attr);

              else if (attr->rta_type == RTA_GATEWAY)

                gateway = RTA_DATA (attr);

              else if (attr->rta_type == RTA_OIF)

                oif = RTA_DATA (attr);

              attr = RTA_NEXT (attr, attrlen);

            }

          if (dest || gateway || oif)

            {

              /* Unless we're processing the results of a dump, ignore

               * IPv6 link-local multicast routes, which are added and

               * removed all the time for some reason.

               */

#define UNALIGNED_IN6_IS_ADDR_MC_LINKLOCAL(a)           \

              ((a[0] == 0xff) && ((a[1] & 0xf) == 0x2))

              if (!nl->priv->dump_networks &&

                  rtmsg->rtm_family == AF_INET6 &&

                  rtmsg->rtm_dst_len != 0 &&

                  (dest && UNALIGNED_IN6_IS_ADDR_MC_LINKLOCAL (dest)))

                continue;

              if (msg->nlmsg_type == RTM_NEWROUTE)

                add_network (nl, rtmsg->rtm_family, dest, rtmsg->rtm_dst_len);

              else

                remove_network (nl, rtmsg->rtm_family, dest, rtmsg->rtm_dst_len);

              queue_request_dump (nl);

            }

          break;

        case NLMSG_DONE:

          finish_dump (nl);

          goto done;

        case NLMSG_ERROR:

          {

            struct nlmsgerr *e = NLMSG_DATA (msg);

            g_set_error (&local_error,

                         G_IO_ERROR,

                         g_io_error_from_errno (-e->error),

                         "netlink error: %s",

                         g_strerror (-e->error));

          }

          goto done;

        default:

          g_set_error (&local_error,

                       G_IO_ERROR,

                       G_IO_ERROR_INVALID_DATA,

                       "unexpected netlink message %d",

                       msg->nlmsg_type);

          goto done;

        }

    }

 done:

  g_free (iv.buffer);

  g_clear_object (&addr);

  if (local_error != NULL && nl->priv->dump_networks)

    finish_dump (nl);

  if (local_error != NULL)

    {

      g_propagate_prefixed_error (error, local_error, "Error on netlink socket: ");

      return FALSE;

    }

  else

    {

      return TRUE;

    }

}

static void

g_network_monitor_netlink_finalize (GObject *object)

{

  GNetworkMonitorNetlink *nl = G_NETWORK_MONITOR_NETLINK (object);

  if (nl->priv->source)

    {

      g_source_destroy (nl->priv->source);

      g_source_unref (nl->priv->source);

    }

  if (nl->priv->dump_source)

    {

      g_source_destroy (nl->priv->dump_source);

      g_source_unref (nl->priv->dump_source);

    }

  if (nl->priv->sock)

    {

      g_socket_close (nl->priv->sock, NULL);

      g_object_unref (nl->priv->sock);

    }

  g_clear_pointer (&nl->priv->context, g_main_context_unref);

  g_clear_pointer (&nl->priv->dump_networks, g_ptr_array_unref);

  G_OBJECT_CLASS (g_network_monitor_netlink_parent_class)->finalize (object);

}

static gboolean

read_netlink_messages_callback (GSocket      *socket,

                                GIOCondition  condition,

                                gpointer      user_data)

{

  GError *error = NULL;

  GNetworkMonitorNetlink *nl = G_NETWORK_MONITOR_NETLINK (user_data);

  if (!read_netlink_messages (nl, &error))

    {

      g_warning ("Error reading netlink message: %s", error->message);

      g_clear_error (&error);

      return FALSE;

    }

  return TRUE;

}

static void

g_network_monitor_netlink_class_init (GNetworkMonitorNetlinkClass *nl_class)

{

  GObjectClass *gobject_class = G_OBJECT_CLASS (nl_class);

  gobject_class->finalize = g_network_monitor_netlink_finalize;

}

static void

g_network_monitor_netlink_iface_init (GNetworkMonitorInterface *monitor_iface)

{

}

static void

g_network_monitor_netlink_initable_iface_init (GInitableIface *iface)

{

  initable_parent_iface = g_type_interface_peek_parent (iface);

  iface->init = g_network_monitor_netlink_initable_init;

}