178 lines
4.1 KiB
C
178 lines
4.1 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini nslookup implementation for busybox
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*
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*
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* Copyright (C) 2000 by Lineo, inc.
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* Written by John Beppu <beppu@lineo.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include "internal.h"
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#include <ctype.h>
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#include <netdb.h>
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <netinet/in.h>
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/*
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| I'm only implementing non-interactive mode;
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| I totally forgot nslookup even had an interactive mode.
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| [ TODO ]
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| + find out how to use non-default name servers
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| + find out how the real nslookup gets the default name server
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*/
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static const char nslookup_usage[] = "nslookup [HOST]\n\n";
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/* I have to see how the real nslookup does this.
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* I could dig through /etc/resolv.conf, but is there a
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* better (programatic) way?
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*/
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static void server_fprint(FILE * dst)
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{
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fprintf(dst, "Server: %s\n", "something");
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fprintf(dst, "Address: %s\n\n", "something");
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}
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/* only works for IPv4 */
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static int addr_fprint(char *addr, FILE * dst)
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{
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uint8_t split[4];
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uint32_t ip;
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uint32_t *x = (uint32_t *) addr;
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ip = ntohl(*x);
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split[0] = (ip & 0xff000000) >> 24;
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split[1] = (ip & 0x00ff0000) >> 16;
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split[2] = (ip & 0x0000ff00) >> 8;
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split[3] = (ip & 0x000000ff);
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fprintf(dst, "%d.%d.%d.%d", split[0], split[1], split[2], split[3]
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);
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return 0;
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}
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/* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
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* into a uint32_t
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*/
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static uint32_t str_to_addr(const char *addr)
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{
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uint32_t split[4];
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uint32_t ip;
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sscanf(addr, "%d.%d.%d.%d",
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&split[0], &split[1], &split[2], &split[3]);
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/* assuming sscanf worked */
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ip = (split[0] << 24) |
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(split[1] << 16) | (split[2] << 8) | (split[3]);
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return htonl(ip);
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}
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/* takes the NULL-terminated array h_addr_list, and
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* prints its contents appropriately
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*/
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static int addr_list_fprint(char **h_addr_list, FILE * dst)
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{
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int i, j;
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char *addr_string = (h_addr_list[1])
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? "Addresses" : "Address";
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fprintf(dst, "%s: ", addr_string);
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for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
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addr_fprint(h_addr_list[i], dst);
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/* real nslookup does this */
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if (j == 4) {
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if (h_addr_list[i + 1]) {
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fprintf(dst, "\n ");
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}
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j = 0;
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} else {
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if (h_addr_list[i + 1]) {
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fprintf(dst, ", ");
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}
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}
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}
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fprintf(dst, "\n");
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return 0;
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}
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/* gethostbyaddr wrapper */
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static struct hostent *gethostbyaddr_wrapper(const char *address)
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{
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struct in_addr addr;
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addr.s_addr = str_to_addr(address);
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return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */
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}
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/* print the results as nslookup would */
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static struct hostent *hostent_fprint(struct hostent *host, FILE * dst)
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{
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if (host) {
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fprintf(dst, "Name: %s\n", host->h_name);
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addr_list_fprint(host->h_addr_list, dst);
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} else {
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fprintf(dst, "*** %s\n", hstrerror(h_errno));
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}
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return host;
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}
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/* naive function to check whether char *s is an ip address */
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static int is_ip_address(const char *s)
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{
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while (*s) {
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if ((isdigit(*s)) || (*s == '.')) {
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s++;
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continue;
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}
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return 0;
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}
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return 1;
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}
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/* ________________________________________________________________________ */
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int nslookup_main(int argc, char **argv)
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{
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struct hostent *host;
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if (argc < 2) {
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usage(nslookup_usage);
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}
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server_fprint(stdout);
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if (is_ip_address(argv[1])) {
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host = gethostbyaddr_wrapper(argv[1]);
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} else {
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host = gethostbyname(argv[1]);
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}
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hostent_fprint(host, stdout);
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return 0;
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}
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/* $Id: nslookup.c,v 1.4 2000/02/08 19:58:47 erik Exp $ */
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