src/posix/netconf.c

   1 /*****************************************************************************
   2  * netconf.c : Network configuration
   3  *****************************************************************************
   4  * Copyright (C) 2013 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <signal.h>
  28
  29 #include <sys/types.h>
  30 #include <sys/wait.h>
  31 #include <fcntl.h>
  32 #include <spawn.h>
  33 #include <unistd.h>
  34
  35 extern char **environ;
  36
  37 #include <vlc_common.h>
  38 #include <vlc_fs.h>
  39 #include <vlc_network.h>
  40
  41 /**
  42  * Determines the network proxy server to use (if any).
  43  * @param url absolute URL for which to get the proxy server
  44  * @return proxy URL, NULL if no proxy or error
  45  */
  46 char *vlc_getProxyUrl(const char *url)
  47 {
  48     /* libproxy helper */
  49     pid_t pid;
  50     posix_spawn_file_actions_t actions;
  51     posix_spawnattr_t attr;
  52     char *argv[3] = { (char *)"proxy", (char *)url, NULL };
  53     int fd[2];
  54
  55     if (vlc_pipe(fd))
  56         return NULL;
  57
  58     posix_spawn_file_actions_init(&actions);
  59     posix_spawn_file_actions_addopen(&actions, STDIN_FILENO, "/dev/null",
  60                                      O_RDONLY, 0644);
  61     posix_spawn_file_actions_adddup2(&actions, fd[1], STDOUT_FILENO);
  62
  63     posix_spawnattr_init(&attr);
  64     {
  65         sigset_t set;
  66
  67         sigemptyset(&set);
  68         posix_spawnattr_setsigmask(&attr, &set);
  69         sigaddset (&set, SIGPIPE);
  70         posix_spawnattr_setsigdefault(&attr, &set);
  71         posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGDEF
  72                                       | POSIX_SPAWN_SETSIGMASK);
  73     }
  74
  75     if (posix_spawnp(&pid, "proxy", &actions, &attr, argv, environ))
  76         pid = -1;
  77
  78     posix_spawnattr_destroy(&attr);
  79     posix_spawn_file_actions_destroy(&actions);
  80     close(fd[1]);
  81
  82     if (pid != -1)
  83     {
  84         char buf[1024];
  85         size_t len = 0;
  86
  87         do
  88         {
  89              ssize_t val = read(fd[0], buf + len, sizeof (buf) - len);
  90              if (val <= 0)
  91                  break;
  92              len += val;
  93         }
  94         while (len < sizeof (buf));
  95
  96         close(fd[0]);
  97         while (waitpid(pid, &(int){ 0 }, 0) == -1);
  98
  99         if (len >= 9 && !strncasecmp(buf, "direct://", 9))
 100             return NULL;
 101
 102         char *end = memchr(buf, '\n', len);
 103         if (end != NULL)
 104         {
 105             *end = '\0';
 106             return strdup(buf);
 107         }
 108         /* Parse error: fallback (may be due to missing executable) */
 109     }
 110     else
 111         close(fd[0]);
 112
 113     /* Fallback to environment variable */
 114     char *var = getenv("http_proxy");
 115     if (var != NULL)
 116         var = strdup(var);
 117     return var;
 118 }