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|
/* vi: set sw=4 ts=4: */
/*
* Mini nslookup implementation for busybox
*
* Copyright (C) 2000 by Lineo, inc.
* Written by John Beppu <beppu@lineo.com>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include "internal.h"
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
/*
| I'm only implementing non-interactive mode;
| I totally forgot nslookup even had an interactive mode.
|
| [ TODO ]
| + find out how to use non-default name servers
| + find out how the real nslookup gets the default name server
*/
static const char nslookup_usage[] = "nslookup [HOST]\n\nQueries the nameserver for the IP address of the given HOST\n";
/* I have to see how the real nslookup does this.
* I could dig through /etc/resolv.conf, but is there a
* better (programatic) way?
*/
static void server_fprint(FILE * dst)
{
fprintf(dst, "Server: %s\n", "default");
fprintf(dst, "Address: %s\n\n", "default");
}
/* only works for IPv4 */
static int addr_fprint(char *addr, FILE * dst)
{
u_int8_t split[4];
u_int32_t ip;
u_int32_t *x = (u_int32_t *) addr;
ip = ntohl(*x);
split[0] = (ip & 0xff000000) >> 24;
split[1] = (ip & 0x00ff0000) >> 16;
split[2] = (ip & 0x0000ff00) >> 8;
split[3] = (ip & 0x000000ff);
fprintf(dst, "%d.%d.%d.%d", split[0], split[1], split[2], split[3]
);
return 0;
}
/* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
* into a u_int32_t
*/
static u_int32_t str_to_addr(const char *addr)
{
u_int32_t split[4];
u_int32_t ip;
sscanf(addr, "%d.%d.%d.%d",
&split[0], &split[1], &split[2], &split[3]);
/* assuming sscanf worked */
ip = (split[0] << 24) |
(split[1] << 16) | (split[2] << 8) | (split[3]);
return htonl(ip);
}
/* takes the NULL-terminated array h_addr_list, and
* prints its contents appropriately
*/
static int addr_list_fprint(char **h_addr_list, FILE * dst)
{
int i, j;
char *addr_string = (h_addr_list[1])
? "Addresses: " : "Address: ";
fprintf(dst, "%s ", addr_string);
for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
addr_fprint(h_addr_list[i], dst);
/* real nslookup does this */
if (j == 4) {
if (h_addr_list[i + 1]) {
fprintf(dst, "\n ");
}
j = 0;
} else {
if (h_addr_list[i + 1]) {
fprintf(dst, ", ");
}
}
}
fprintf(dst, "\n");
return 0;
}
/* gethostbyaddr wrapper */
static struct hostent *gethostbyaddr_wrapper(const char *address)
{
struct in_addr addr;
addr.s_addr = str_to_addr(address);
return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */
}
/* print the results as nslookup would */
static struct hostent *hostent_fprint(struct hostent *host, FILE * dst)
{
if (host) {
fprintf(dst, "Name: %s\n", host->h_name);
addr_list_fprint(host->h_addr_list, dst);
} else {
fprintf(dst, "*** %s\n", hstrerror(h_errno));
}
return host;
}
/* naive function to check whether char *s is an ip address */
static int is_ip_address(const char *s)
{
while (*s) {
if ((isdigit(*s)) || (*s == '.')) {
s++;
continue;
}
return 0;
}
return 1;
}
/* ________________________________________________________________________ */
int nslookup_main(int argc, char **argv)
{
struct hostent *host;
if (argc < 2 || *argv[1]=='-') {
usage(nslookup_usage);
}
server_fprint(stdout);
if (is_ip_address(argv[1])) {
host = gethostbyaddr_wrapper(argv[1]);
} else {
host = gethostbyname(argv[1]);
}
hostent_fprint(host, stdout);
exit( TRUE);
}
/* $Id: nslookup.c,v 1.7 2000/04/15 16:34:54 erik Exp $ */
|
