source: branches/stable/mindi-busybox/networking/nslookup.c @ 821

Last change on this file since 821 was 821, checked in by bruno, 13 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)

File size: 4.9 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * Mini nslookup implementation for busybox
4 *
5 * Copyright (C) 1999,2000 by Lineo, inc. and John Beppu
6 * Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
7 *
8 * Correct default name server display and explicit name server option
9 * added by Ben Zeckel <bzeckel@hmc.edu> June 2001
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 *
25 */
26
27#include <ctype.h>
28#include <errno.h>
29#include <stdio.h>
30#include <string.h>
31#include <stdlib.h>
32
33#include <stdint.h>
34#include <netdb.h>
35#include <sys/socket.h>
36#include <sys/types.h>
37#include <netinet/in.h>
38#include <resolv.h>
39#include <arpa/inet.h>
40#include "busybox.h"
41
42/*
43 |  I'm only implementing non-interactive mode;
44 |  I totally forgot nslookup even had an interactive mode.
45 */
46
47/* only works for IPv4 */
48static int addr_fprint(char *addr)
49{
50    uint8_t split[4];
51    uint32_t ip;
52    uint32_t *x = (uint32_t *) addr;
53
54    ip = ntohl(*x);
55    split[0] = (ip & 0xff000000) >> 24;
56    split[1] = (ip & 0x00ff0000) >> 16;
57    split[2] = (ip & 0x0000ff00) >> 8;
58    split[3] = (ip & 0x000000ff);
59    printf("%d.%d.%d.%d", split[0], split[1], split[2], split[3]);
60    return 0;
61}
62
63/* takes the NULL-terminated array h_addr_list, and
64 * prints its contents appropriately
65 */
66static int addr_list_fprint(char **h_addr_list)
67{
68    int i, j;
69    char *addr_string = (h_addr_list[1])
70        ? "Addresses: " : "Address:   ";
71
72    printf("%s ", addr_string);
73    for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
74        addr_fprint(h_addr_list[i]);
75
76        /* real nslookup does this */
77        if (j == 4) {
78            if (h_addr_list[i + 1]) {
79                printf("\n          ");
80            }
81            j = 0;
82        } else {
83            if (h_addr_list[i + 1]) {
84                printf(", ");
85            }
86        }
87
88    }
89    printf("\n");
90    return 0;
91}
92
93/* print the results as nslookup would */
94static struct hostent *hostent_fprint(struct hostent *host, const char *server_host)
95{
96    if (host) {
97        printf("%s     %s\n", server_host, host->h_name);
98        addr_list_fprint(host->h_addr_list);
99    } else {
100        printf("*** Unknown host\n");
101    }
102    return host;
103}
104
105/* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
106 * into a uint32_t
107 */
108static uint32_t str_to_addr(const char *addr)
109{
110    uint32_t split[4];
111    uint32_t ip;
112
113    sscanf(addr, "%d.%d.%d.%d",
114           &split[0], &split[1], &split[2], &split[3]);
115
116    /* assuming sscanf worked */
117    ip = (split[0] << 24) |
118        (split[1] << 16) | (split[2] << 8) | (split[3]);
119
120    return htonl(ip);
121}
122
123/* gethostbyaddr wrapper */
124static struct hostent *gethostbyaddr_wrapper(const char *address)
125{
126    struct in_addr addr;
127
128    addr.s_addr = str_to_addr(address);
129    return gethostbyaddr((char *) &addr, 4, AF_INET);   /* IPv4 only for now */
130}
131
132/* lookup the default nameserver and display it */
133static inline void server_print(void)
134{
135    struct sockaddr_in def = _res.nsaddr_list[0];
136    char *ip = inet_ntoa(def.sin_addr);
137
138    hostent_fprint(gethostbyaddr_wrapper(ip), "Server:");
139    printf("\n");
140}
141
142/* alter the global _res nameserver structure to use
143   an explicit dns server instead of what is in /etc/resolv.h */
144static inline void set_default_dns(char *server)
145{
146    struct in_addr server_in_addr;
147
148    if(inet_aton(server,&server_in_addr))
149    {
150        _res.nscount = 1;
151        _res.nsaddr_list[0].sin_addr = server_in_addr;
152    }
153}
154
155/* naive function to check whether char *s is an ip address */
156static int is_ip_address(const char *s)
157{
158    while (*s) {
159        if ((isdigit(*s)) || (*s == '.')) {
160            s++;
161            continue;
162        }
163        return 0;
164    }
165    return 1;
166}
167
168/* ________________________________________________________________________ */
169int nslookup_main(int argc, char **argv)
170{
171    struct hostent *host;
172
173    /*
174    * initialize DNS structure _res used in printing the default
175    * name server and in the explicit name server option feature.
176    */
177
178    res_init();
179
180    /*
181    * We allow 1 or 2 arguments.
182    * The first is the name to be looked up and the second is an
183    * optional DNS server with which to do the lookup.
184    * More than 3 arguments is an error to follow the pattern of the
185    * standard nslookup
186    */
187
188    if (argc < 2 || *argv[1]=='-' || argc > 3)
189        bb_show_usage();
190    else if(argc == 3)
191        set_default_dns(argv[2]);
192
193    server_print();
194    if (is_ip_address(argv[1])) {
195        host = gethostbyaddr_wrapper(argv[1]);
196    } else {
197        host = xgethostbyname(argv[1]);
198    }
199    hostent_fprint(host, "Name:  ");
200    if (host) {
201        return EXIT_SUCCESS;
202    }
203    return EXIT_FAILURE;
204}
205
206/* $Id: nslookup.c,v 1.33 2004/10/13 07:25:01 andersen Exp $ */
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