package/resolveip/src/resolveip.c

   1 /*
   2  * Based on code found at https://dev.openwrt.org/ticket/4876 .
   3  * Extended by Jo-Philipp Wich <jow@openwrt.org> for use in OpenWrt.
   4  *
   5  * You may use this program under the terms of the GPLv2 license.
   6  */
   7
   8 #include <string.h>
   9 #include <stdio.h>
  10 #include <sys/types.h>
  11 #include <sys/socket.h>
  12 #include <netdb.h>
  13 #include <arpa/inet.h>
  14 #include <netinet/in.h>
  15 #include <stdlib.h>
  16 #include <unistd.h>
  17 #include <signal.h>
  18
  19
  20 static void abort_query(int sig)
  21 {
  22         exit(1);
  23 }
  24
  25 static void show_usage(void)
  26 {
  27         printf("Usage:\n");
  28         printf("        resolveip -h\n");
  29         printf("        resolveip [-t timeout] hostname\n");
  30         printf("        resolveip -4 [-t timeout] hostname\n");
  31         printf("        resolveip -6 [-t timeout] hostname\n");
  32         exit(255);
  33 }
  34
  35 int main(int argc, char **argv)
  36 {
  37         int timeout = 3;
  38         char opt;
  39         char ipaddr[INET6_ADDRSTRLEN];
  40         void *addr;
  41         struct addrinfo *res, *rp;
  42         struct sigaction sa = { .sa_handler = &abort_query };
  43         struct addrinfo hints = {
  44                 .ai_family   = AF_UNSPEC,
  45                 .ai_socktype = SOCK_STREAM,
  46                 .ai_protocol = IPPROTO_TCP,
  47                 .ai_flags    = 0
  48         };
  49
  50         while ((opt = getopt(argc, argv, "46t:h")) > -1)
  51         {
  52                 switch (opt)
  53                 {
  54                         case '4':
  55                                 hints.ai_family = AF_INET;
  56                                 break;
  57
  58                         case '6':
  59                                 hints.ai_family = AF_INET6;
  60                                 break;
  61
  62                         case 't':
  63                                 timeout = atoi(optarg);
  64                                 if (timeout <= 0)
  65                                         show_usage();
  66                                 break;
  67
  68                         case 'h':
  69                                 show_usage();
  70                                 break;
  71                 }
  72         }
  73
  74         if (!argv[optind])
  75                 show_usage();
  76
  77         sigaction(SIGALRM, &sa, NULL);
  78         alarm(timeout);
  79
  80         if (getaddrinfo(argv[optind], NULL, &hints, &res))
  81                 exit(2);
  82
  83         for (rp = res; rp != NULL; rp = rp->ai_next)
  84         {
  85                 addr = (rp->ai_family == AF_INET)
  86                         ? (void *)&((struct sockaddr_in *)rp->ai_addr)->sin_addr
  87                         : (void *)&((struct sockaddr_in6 *)rp->ai_addr)->sin6_addr
  88                 ;
  89
  90                 if (!inet_ntop(rp->ai_family, addr, ipaddr, INET6_ADDRSTRLEN - 1))
  91                         exit(3);
  92
  93                 printf("%s\n", ipaddr);
  94         }
  95
  96         freeaddrinfo(res);
  97         exit(0);
  98 }