gethostip.c

#ident "$Id$"
/* ----------------------------------------------------------------------- *
 *   
 *   Copyright 2001-2004 H. Peter Anvin - All Rights Reserved
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * gethostip.c
 *
 * Small program to use gethostbyname() to print out a hostname in
 * hex and/or dotted-quad notation
 */

#include <stdio.h>
#include <stdlib.h>
#include <netdb.h>
#include <sys/socket.h>
#include <unistd.h>
#include <sysexits.h>
#define _GNU_SOURCE		/* For getopt_long */
#include <getopt.h>

const struct option options[] =
{
  { "hexadecimal", 0, NULL, 'x' },
  { "decimal",     0, NULL, 'd' },
  { "dotted-quad", 0, NULL, 'd' },
  { "full-output", 0, NULL, 'f' },
  { "name",        0, NULL, 'n' },
  { "help",        0, NULL, 'h' },
  { NULL, 0, NULL, 0 }
};

const char *program;

void usage(int exit_code)
{
  fprintf(stderr, "Usage: %s [-dxnf] hostname/ip...\n", program);
  exit(exit_code);
}

int main(int argc, char *argv[])
{
  int opt;
  int output = 0;
  int i;
  char *sep;
  int err = 0;

  struct hostent *host;

  program = argv[0];

  while ( (opt = getopt_long(argc, argv, "dxfnh", options, NULL)) != -1 ) {
    switch ( opt ) {
    case 'd':
      output |= 2;		/* Decimal output */
      break;
    case 'x':
      output |= 4;		/* Hexadecimal output */
      break;
    case 'n':
      output |= 1;		/* Canonical name output */
      break;
    case 'f':
      output = 7;		/* Full output */
      break;
    case 'h':
      usage(0);
      break;
    default:
      usage(EX_USAGE);
      break;
    }
  }

  if ( optind == argc )
    usage(EX_USAGE);

  if ( output == 0 )
    output = 7;			/* Default output */

  for ( i = optind ; i < argc ; i++ ) {
    sep = "";
    host = gethostbyname(argv[i]);
    if ( !host ) {
      herror(argv[i]);
      err = 1;
      continue;
    }

    if ( host->h_addrtype != AF_INET || host->h_length != 4 ) {
      fprintf(stderr, "%s: No IPv4 address associated with name\n", argv[i]);
      err = 1;
      continue;
    }

    if ( output & 1 ) {
      printf("%s%s", sep, host->h_name);
      sep = " ";
    }

    if ( output & 2 ) {
      printf("%s%u.%u.%u.%u", sep,
	     ((unsigned char *)host->h_addr)[0],
	     ((unsigned char *)host->h_addr)[1],
	     ((unsigned char *)host->h_addr)[2],
	     ((unsigned char *)host->h_addr)[3]);
      sep = " ";
    }

    if ( output & 4 ) {
      printf("%s%02X%02X%02X%02X", sep,
	     ((unsigned char *)host->h_addr)[0],
	     ((unsigned char *)host->h_addr)[1],
	     ((unsigned char *)host->h_addr)[2],
	     ((unsigned char *)host->h_addr)[3]);
      sep = " ";
    }

    putchar('\n');
  }

  return err;
}