src/linux/getaddrinfo.c

   1 /*****************************************************************************
   2  * linux/getaddrinfo.c: interruptible DNS resolution for Linux
   3  *****************************************************************************
   4  * Copyright (C) 2016 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 <assert.h>
  26 #include <stdio.h>
  27 #include <netdb.h>
  28 #include <signal.h>
  29
  30 #include <vlc_common.h>
  31 #include <vlc_interrupt.h>
  32 #include <vlc_network.h>
  33
  34 static void vlc_getaddrinfo_notify(union sigval val)
  35 {
  36     vlc_sem_post(val.sival_ptr);
  37 }
  38
  39 int vlc_getaddrinfo_i11e(const char *name, unsigned port,
  40                          const struct addrinfo *hints,
  41                          struct addrinfo **res)
  42 {
  43     struct gaicb req =
  44     {
  45         .ar_name = name,
  46         .ar_service = NULL,
  47         .ar_request = hints,
  48     };
  49     char portbuf[6];
  50     vlc_sem_t done;
  51
  52     if (port != 0)
  53     {
  54         if ((size_t)snprintf(portbuf, sizeof (portbuf), "%u",
  55                              port) >= sizeof (portbuf))
  56             return EAI_NONAME;
  57
  58         req.ar_service = portbuf;
  59     }
  60
  61     struct sigevent sev =
  62     {
  63         .sigev_notify = SIGEV_THREAD,
  64         .sigev_value = { .sival_ptr = &done, },
  65         .sigev_notify_function = vlc_getaddrinfo_notify,
  66     };
  67
  68     vlc_sem_init(&done, 0);
  69
  70     int val = getaddrinfo_a(GAI_NOWAIT, &(struct gaicb *){ &req }, 1, &sev);
  71     if (val)
  72     {
  73         vlc_sem_destroy(&done);
  74         return val;
  75     }
  76
  77     vlc_sem_wait_i11e(&done);
  78
  79     if (gai_cancel(&req) == EAI_CANCELED)
  80         vlc_sem_wait(&done);
  81
  82     while (gai_suspend(&(const struct gaicb *){ &req }, 1, NULL) == EAI_INTR);
  83
  84     val = gai_error(&req);
  85     assert(val != EAI_INPROGRESS);
  86
  87     if (val == 0)
  88         *res = req.ar_result;
  89
  90     return val;
  91 }