gethostip.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2001-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * gethostip.c
  15  *
  16  * Small program to use gethostbyname() to print out a hostname in
  17  * hex and/or dotted-quad notation
  18  */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <netdb.h>
  23 #include <sys/socket.h>
  24 #include <unistd.h>
  25 #include <sysexits.h>
  26 #define _GNU_SOURCE             /* For getopt_long */
  27 #include <getopt.h>
  28
  29 const struct option options[] =
  30 {
  31   { "hexadecimal", 0, NULL, 'x' },
  32   { "decimal",     0, NULL, 'd' },
  33   { "dotted-quad", 0, NULL, 'd' },
  34   { "full-output", 0, NULL, 'f' },
  35   { "name",        0, NULL, 'n' },
  36   { "help",        0, NULL, 'h' },
  37   { NULL, 0, NULL, 0 }
  38 };
  39
  40 const char *program;
  41
  42 void usage(int exit_code)
  43 {
  44   fprintf(stderr, "Usage: %s [-dxnf] hostname/ip...\n", program);
  45   exit(exit_code);
  46 }
  47
  48 int main(int argc, char *argv[])
  49 {
  50   int opt;
  51   int output = 0;
  52   int i;
  53   char *sep;
  54   int err = 0;
  55
  56   struct hostent *host;
  57
  58   program = argv[0];
  59
  60   while ( (opt = getopt_long(argc, argv, "dxfnh", options, NULL)) != -1 ) {
  61     switch ( opt ) {
  62     case 'd':
  63       output |= 2;              /* Decimal output */
  64       break;
  65     case 'x':
  66       output |= 4;              /* Hexadecimal output */
  67       break;
  68     case 'n':
  69       output |= 1;              /* Canonical name output */
  70       break;
  71     case 'f':
  72       output = 7;               /* Full output */
  73       break;
  74     case 'h':
  75       usage(0);
  76       break;
  77     default:
  78       usage(EX_USAGE);
  79       break;
  80     }
  81   }
  82
  83   if ( optind == argc )
  84     usage(EX_USAGE);
  85
  86   if ( output == 0 )
  87     output = 7;                 /* Default output */
  88
  89   for ( i = optind ; i < argc ; i++ ) {
  90     sep = "";
  91     host = gethostbyname(argv[i]);
  92     if ( !host ) {
  93       herror(argv[i]);
  94       err = 1;
  95       continue;
  96     }
  97
  98     if ( host->h_addrtype != AF_INET || host->h_length != 4 ) {
  99       fprintf(stderr, "%s: No IPv4 address associated with name\n", argv[i]);
 100       err = 1;
 101       continue;
 102     }
 103
 104     if ( output & 1 ) {
 105       printf("%s%s", sep, host->h_name);
 106       sep = " ";
 107     }
 108
 109     if ( output & 2 ) {
 110       printf("%s%u.%u.%u.%u", sep,
 111              ((unsigned char *)host->h_addr)[0],
 112              ((unsigned char *)host->h_addr)[1],
 113              ((unsigned char *)host->h_addr)[2],
 114              ((unsigned char *)host->h_addr)[3]);
 115       sep = " ";
 116     }
 117
 118     if ( output & 4 ) {
 119       printf("%s%02X%02X%02X%02X", sep,
 120              ((unsigned char *)host->h_addr)[0],
 121              ((unsigned char *)host->h_addr)[1],
 122              ((unsigned char *)host->h_addr)[2],
 123              ((unsigned char *)host->h_addr)[3]);
 124       sep = " ";
 125     }
 126
 127     putchar('\n');
 128   }
 129
 130   return err;
 131 }