1 /* vi: set sw=4 ts=4: */
3 * Mini nslookup implementation for busybox
5 * Copyright (C) 1999,2000 by Lineo, inc. and John Beppu
6 * Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
8 * Correct default name server display and explicit name server option
9 * added by Ben Zeckel <bzeckel@hmc.edu> June 2001
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.
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.
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
34 #include <sys/socket.h>
35 #include <sys/types.h>
36 #include <netinet/in.h>
38 #include <arpa/inet.h>
42 | I'm only implementing non-interactive mode;
43 | I totally forgot nslookup even had an interactive mode.
46 /* only works for IPv4 */
47 static int addr_fprint(char *addr)
51 u_int32_t *x = (u_int32_t *) addr;
54 split[0] = (ip & 0xff000000) >> 24;
55 split[1] = (ip & 0x00ff0000) >> 16;
56 split[2] = (ip & 0x0000ff00) >> 8;
57 split[3] = (ip & 0x000000ff);
58 printf("%d.%d.%d.%d", split[0], split[1], split[2], split[3]);
62 /* takes the NULL-terminated array h_addr_list, and
63 * prints its contents appropriately
65 static int addr_list_fprint(char **h_addr_list)
68 char *addr_string = (h_addr_list[1])
69 ? "Addresses: " : "Address: ";
71 printf("%s ", addr_string);
72 for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
73 addr_fprint(h_addr_list[i]);
75 /* real nslookup does this */
77 if (h_addr_list[i + 1]) {
82 if (h_addr_list[i + 1]) {
92 /* print the results as nslookup would */
93 static struct hostent *hostent_fprint(struct hostent *host, const char *server_host)
96 printf("%s %s\n", server_host, host->h_name);
97 addr_list_fprint(host->h_addr_list);
99 printf("*** Unknown host\n");
104 /* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
107 static u_int32_t str_to_addr(const char *addr)
112 sscanf(addr, "%d.%d.%d.%d",
113 &split[0], &split[1], &split[2], &split[3]);
115 /* assuming sscanf worked */
116 ip = (split[0] << 24) |
117 (split[1] << 16) | (split[2] << 8) | (split[3]);
122 /* gethostbyaddr wrapper */
123 static struct hostent *gethostbyaddr_wrapper(const char *address)
127 addr.s_addr = str_to_addr(address);
128 return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */
131 /* lookup the default nameserver and display it */
132 static inline void server_print(void)
134 struct sockaddr_in def = _res.nsaddr_list[0];
135 char *ip = inet_ntoa(def.sin_addr);
137 hostent_fprint(gethostbyaddr_wrapper(ip), "Server:");
141 /* alter the global _res nameserver structure to use
142 an explicit dns server instead of what is in /etc/resolv.h */
143 static inline void set_default_dns(char *server)
145 struct in_addr server_in_addr;
147 if(inet_aton(server,&server_in_addr))
150 _res.nsaddr_list[0].sin_addr = server_in_addr;
154 /* naive function to check whether char *s is an ip address */
155 static int is_ip_address(const char *s)
158 if ((isdigit(*s)) || (*s == '.')) {
167 /* ________________________________________________________________________ */
168 int nslookup_main(int argc, char **argv)
170 struct hostent *host;
173 * initialize DNS structure _res used in printing the default
174 * name server and in the explicit name server option feature.
180 * We allow 1 or 2 arguments.
181 * The first is the name to be looked up and the second is an
182 * optional DNS server with which to do the lookup.
183 * More than 3 arguments is an error to follow the pattern of the
187 if (argc < 2 || *argv[1]=='-' || argc > 3)
190 set_default_dns(argv[2]);
193 if (is_ip_address(argv[1])) {
194 host = gethostbyaddr_wrapper(argv[1]);
196 host = xgethostbyname(argv[1]);
198 hostent_fprint(host, "Name: ");
202 /* $Id: nslookup.c,v 1.29 2002/07/24 00:56:56 sandman Exp $ */