/*
 * Cut-down version of common/flatpak-run.c from Flatpak
 *
 * Copyright © 2017-2019 Collabora Ltd.
 * Copyright © 2014-2019 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 "flatpak-run-private.h"

#include <sys/utsname.h>

#include <X11/Xauth.h>
#include <gio/gio.h>

#include "flatpak-utils-private.h"

/* In Flatpak this is optional, in pressure-vessel not so much */
#define ENABLE_XAUTH

static char *
extract_unix_path_from_dbus_address (const char *address)
{
  const char *path, *path_end;

  if (address == NULL)
    return NULL;

  if (!g_str_has_prefix (address, "unix:"))
    return NULL;

  path = strstr (address, "path=");
  if (path == NULL)
    return NULL;
  path += strlen ("path=");
  path_end = path;
  while (*path_end != 0 && *path_end != ',')
    path_end++;

  return g_strndup (path, path_end - path);
}

#ifdef ENABLE_XAUTH
static gboolean
auth_streq (char *str,
            char *au_str,
            int   au_len)
{
  return au_len == strlen (str) && memcmp (str, au_str, au_len) == 0;
}

static gboolean
xauth_entry_should_propagate (Xauth *xa,
                              char  *hostname,
                              char  *number)
{
  /* ensure entry isn't for remote access */
  if (xa->family != FamilyLocal && xa->family != FamilyWild)
    return FALSE;

  /* ensure entry is for this machine */
  if (xa->family == FamilyLocal && !auth_streq (hostname, xa->address, xa->address_length))
    return FALSE;

  /* ensure entry is for this session */
  if (xa->number != NULL && !auth_streq (number, xa->number, xa->number_length))
    return FALSE;

  return TRUE;
}

static void
write_xauth (char *number, FILE *output)
{
  Xauth *xa, local_xa;
  char *filename;
  FILE *f;
  struct utsname unames;

  if (uname (&unames))
    {
      g_warning ("uname failed");
      return;
    }

  filename = XauFileName ();
  f = fopen (filename, "rb");
  if (f == NULL)
    return;

  while (TRUE)
    {
      xa = XauReadAuth (f);
      if (xa == NULL)
        break;
      if (xauth_entry_should_propagate (xa, unames.nodename, number))
        {
          local_xa = *xa;
          if (local_xa.number)
            {
              local_xa.number = (char *) "99";
              local_xa.number_length = 2;
            }

          if (!XauWriteAuth (output, &local_xa))
            g_warning ("xauth write error");
        }

      XauDisposeAuth (xa);
    }

  fclose (f);
}
#endif

void
flatpak_run_add_x11_args (FlatpakBwrap *bwrap,
                          gboolean      allowed)
{
  g_autofree char *x11_socket = NULL;
  const char *display;

  /* Always cover /tmp/.X11-unix, that way we never see the host one in case
   * we have access to the host /tmp. If you request X access we'll put the right
   * thing in this anyway.
   */
  flatpak_bwrap_add_args (bwrap,
                          "--tmpfs", "/tmp/.X11-unix",
                          NULL);

  if (!allowed)
    {
      flatpak_bwrap_unset_env (bwrap, "DISPLAY");
      return;
    }

  g_debug ("Allowing x11 access");

  display = g_getenv ("DISPLAY");
  if (display && display[0] == ':' && g_ascii_isdigit (display[1]))
    {
      const char *display_nr = &display[1];
      const char *display_nr_end = display_nr;
      g_autofree char *d = NULL;

      while (g_ascii_isdigit (*display_nr_end))
        display_nr_end++;

      d = g_strndup (display_nr, display_nr_end - display_nr);
      x11_socket = g_strdup_printf ("/tmp/.X11-unix/X%s", d);

      flatpak_bwrap_add_args (bwrap,
                              "--ro-bind", x11_socket, "/tmp/.X11-unix/X99",
                              NULL);
      flatpak_bwrap_set_env (bwrap, "DISPLAY", ":99.0", TRUE);

#ifdef ENABLE_XAUTH
      g_auto(GLnxTmpfile) xauth_tmpf  = { 0, };

      if (glnx_open_anonymous_tmpfile (O_RDWR | O_CLOEXEC, &xauth_tmpf, NULL))
        {
          FILE *output = fdopen (xauth_tmpf.fd, "wb");
          if (output != NULL)
            {
              /* fd is now owned by output, steal it from the tmpfile */
              int tmp_fd = dup (glnx_steal_fd (&xauth_tmpf.fd));
              if (tmp_fd != -1)
                {
                  g_autofree char *dest = g_strdup_printf ("/run/user/%d/Xauthority", getuid ());

                  write_xauth (d, output);
                  flatpak_bwrap_add_args_data_fd (bwrap, "--ro-bind-data", tmp_fd, dest);

                  flatpak_bwrap_set_env (bwrap, "XAUTHORITY", dest, TRUE);
                }

              fclose (output);

              if (tmp_fd != -1)
                lseek (tmp_fd, 0, SEEK_SET);
            }
        }
#endif
    }
  else
    {
      flatpak_bwrap_unset_env (bwrap, "DISPLAY");
    }
}

gboolean
flatpak_run_add_wayland_args (FlatpakBwrap *bwrap)
{
  const char *wayland_display;
  g_autofree char *user_runtime_dir = flatpak_get_real_xdg_runtime_dir ();
  g_autofree char *wayland_socket = NULL;
  g_autofree char *sandbox_wayland_socket = NULL;
  gboolean res = FALSE;
  struct stat statbuf;

  wayland_display = g_getenv ("WAYLAND_DISPLAY");
  if (!wayland_display)
    wayland_display = "wayland-0";

  wayland_socket = g_build_filename (user_runtime_dir, wayland_display, NULL);
  sandbox_wayland_socket = g_strdup_printf ("/run/user/%d/%s", getuid (), wayland_display);

  if (stat (wayland_socket, &statbuf) == 0 &&
      (statbuf.st_mode & S_IFMT) == S_IFSOCK)
    {
      res = TRUE;
      flatpak_bwrap_add_args (bwrap,
                              "--ro-bind", wayland_socket, sandbox_wayland_socket,
                              NULL);
    }
  return res;
}

/* Try to find a default server from a pulseaudio confguration file */
static char *
flatpak_run_get_pulseaudio_server_user_config (const char *path)
{
  g_autoptr(GFile) file = g_file_new_for_path (path);
  g_autoptr(GError) my_error = NULL;
  g_autoptr(GFileInputStream) input_stream = NULL;
  g_autoptr(GDataInputStream) data_stream = NULL;
  size_t len;

  input_stream = g_file_read (file, NULL, &my_error);
  if (my_error)
    {
      g_debug ("Pulseaudio user configuration file '%s': %s", path, my_error->message);
      return NULL;
    }

  data_stream = g_data_input_stream_new (G_INPUT_STREAM (input_stream));

  while (TRUE)
    {
      g_autofree char *line = g_data_input_stream_read_line (data_stream, &len, NULL, NULL);
      if (line == NULL)
        break;

      g_strchug (line);

      if ((*line  == '\0') || (*line == ';') || (*line == '#'))
        continue;

      if (g_str_has_prefix (line, ".include "))
        {
          g_autofree char *rec_path = g_strdup (line + 9);
          g_strstrip (rec_path);
          char *found = flatpak_run_get_pulseaudio_server_user_config (rec_path);
          if (found)
            return found;
        }
      else if (g_str_has_prefix (line, "["))
        {
          return NULL;
        }
      else
        {
          g_auto(GStrv) tokens = g_strsplit (line, "=", 2);

          if ((tokens[0] != NULL) && (tokens[1] != NULL))
            {
              g_strchomp (tokens[0]);
              if (strcmp ("default-server", tokens[0]) == 0)
                {
                  g_strstrip (tokens[1]);
                  g_debug ("Found pulseaudio socket from configuration file '%s': %s", path, tokens[1]);
                  return g_strdup (tokens[1]);
                }
            }
        }
    }

  return NULL;
}

static char *
flatpak_run_get_pulseaudio_server (void)
{
  const char * pulse_clientconfig;
  char *pulse_server;
  g_autofree char *pulse_user_config = NULL;

  pulse_server = g_strdup (g_getenv ("PULSE_SERVER"));
  if (pulse_server)
    return pulse_server;

  pulse_clientconfig = g_getenv ("PULSE_CLIENTCONFIG");
  if (pulse_clientconfig)
    return flatpak_run_get_pulseaudio_server_user_config (pulse_clientconfig);

  pulse_user_config = g_build_filename (g_get_user_config_dir (), "pulse/client.conf", NULL);
  pulse_server = flatpak_run_get_pulseaudio_server_user_config (pulse_user_config);
  if (pulse_server)
    return pulse_server;

  pulse_server = flatpak_run_get_pulseaudio_server_user_config ("/etc/pulse/client.conf");
  if (pulse_server)
    return pulse_server;

  return NULL;
}

static char *
flatpak_run_parse_pulse_server (const char *value)
{
  g_auto(GStrv) servers = g_strsplit (value, " ", 0);
  gsize i;

  for (i = 0; servers[i] != NULL; i++)
    {
      const char *server = servers[i];
      if (g_str_has_prefix (server, "{"))
        {
          const char * closing = strstr (server, "}");
          if (closing == NULL)
            continue;
          server = closing + 1;
        }
      if (g_str_has_prefix (server, "unix:"))
        return g_strdup (server + 5);
    }

  return NULL;
}

void
flatpak_run_add_pulseaudio_args (FlatpakBwrap *bwrap)
{
  g_autofree char *pulseaudio_server = flatpak_run_get_pulseaudio_server ();
  g_autofree char *pulseaudio_socket = NULL;
  g_autofree char *user_runtime_dir = flatpak_get_real_xdg_runtime_dir ();

  if (pulseaudio_server)
    pulseaudio_socket = flatpak_run_parse_pulse_server (pulseaudio_server);

  if (!pulseaudio_socket)
    pulseaudio_socket = g_build_filename (user_runtime_dir, "pulse/native", NULL);

  flatpak_bwrap_unset_env (bwrap, "PULSE_SERVER");

  /* SteamOS system-wide PulseAudio instance */
  if (!g_file_test (pulseaudio_socket, G_FILE_TEST_EXISTS))
    {
      g_clear_pointer (&pulseaudio_socket, g_free);
      pulseaudio_socket = g_strdup ("/var/run/pulse/native");
    }

  if (g_file_test (pulseaudio_socket, G_FILE_TEST_EXISTS))
    {
      gboolean share_shm = FALSE; /* TODO: When do we add this? */
      g_autofree char *client_config = g_strdup_printf ("enable-shm=%s\n", share_shm ? "yes" : "no");
      g_autofree char *sandbox_socket_path = g_strdup_printf ("/run/user/%d/pulse/native", getuid ());
      g_autofree char *pulse_server = g_strdup_printf ("unix:/run/user/%d/pulse/native", getuid ());
      g_autofree char *config_path = g_strdup_printf ("/run/user/%d/pulse/config", getuid ());

      /* FIXME - error handling */
      if (!flatpak_bwrap_add_args_data (bwrap, "pulseaudio", client_config, -1, config_path, NULL))
        return;

      flatpak_bwrap_add_args (bwrap,
                              "--ro-bind", pulseaudio_socket, sandbox_socket_path,
                              NULL);

      flatpak_bwrap_set_env (bwrap, "PULSE_SERVER", pulse_server, TRUE);
      flatpak_bwrap_set_env (bwrap, "PULSE_CLIENTCONFIG", config_path, TRUE);
    }
  else
    g_debug ("Could not find pulseaudio socket");
}

/* Simplified from Flatpak: we never restrict access to the D-Bus system bus */
gboolean
flatpak_run_add_system_dbus_args (FlatpakBwrap   *app_bwrap)
{
  const char *dbus_address = g_getenv ("DBUS_SYSTEM_BUS_ADDRESS");
  g_autofree char *dbus_system_socket = NULL;

  if (dbus_address != NULL)
    dbus_system_socket = extract_unix_path_from_dbus_address (dbus_address);
  else if (g_file_test ("/var/run/dbus/system_bus_socket", G_FILE_TEST_EXISTS))
    dbus_system_socket = g_strdup ("/var/run/dbus/system_bus_socket");

  if (dbus_system_socket != NULL)
    {
      flatpak_bwrap_add_args (app_bwrap,
                              "--ro-bind", dbus_system_socket, "/run/dbus/system_bus_socket",
                              NULL);
      flatpak_bwrap_set_env (app_bwrap, "DBUS_SYSTEM_BUS_ADDRESS", "unix:path=/run/dbus/system_bus_socket", TRUE);

      return TRUE;
    }

  return FALSE;
}

/* Simplified from Flatpak: we never restrict access to the D-Bus session bus */
gboolean
flatpak_run_add_session_dbus_args (FlatpakBwrap   *app_bwrap)
{
  const char *dbus_address = g_getenv ("DBUS_SESSION_BUS_ADDRESS");
  char *dbus_session_socket = NULL;
  g_autofree char *sandbox_socket_path = g_strdup_printf ("/run/user/%d/bus", getuid ());
  g_autofree char *sandbox_dbus_address = g_strdup_printf ("unix:path=/run/user/%d/bus", getuid ());
  g_autofree char *user_runtime_dir = flatpak_get_real_xdg_runtime_dir ();

  /* FIXME: upstream the use of user_runtime_dir to Flatpak */

  if (dbus_address != NULL)
    {
      dbus_session_socket = extract_unix_path_from_dbus_address (dbus_address);
    }
  else
    {
      struct stat statbuf;

      dbus_session_socket = g_build_filename (user_runtime_dir, "bus", NULL);

      if (stat (dbus_session_socket, &statbuf) < 0
          || (statbuf.st_mode & S_IFMT) != S_IFSOCK
          || statbuf.st_uid != getuid ())
        return FALSE;
    }

  if (dbus_session_socket != NULL)
    {
      flatpak_bwrap_add_args (app_bwrap,
                              "--ro-bind", dbus_session_socket, sandbox_socket_path,
                              NULL);
      flatpak_bwrap_set_env (app_bwrap, "DBUS_SESSION_BUS_ADDRESS", sandbox_dbus_address, TRUE);

      return TRUE;
    }

  return FALSE;
}