1 /* vi: set sw=4 ts=4: */
3 * Mini nslookup implementation for busybox
5 * Copyright (C) 2000 by Lineo, inc.
6 * Written by John Beppu <beppu@lineo.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
31 #include <sys/socket.h>
32 #include <sys/types.h>
33 #include <netinet/in.h>
36 | I'm only implementing non-interactive mode;
37 | I totally forgot nslookup even had an interactive mode.
40 | + find out how to use non-default name servers
41 | + find out how the real nslookup gets the default name server
44 static const char nslookup_usage[] = "nslookup [HOST]\n\nQueries the nameserver for the IP address of the given HOST\n";
47 /* I have to see how the real nslookup does this.
48 * I could dig through /etc/resolv.conf, but is there a
49 * better (programatic) way?
51 static void server_fprint(FILE * dst)
53 fprintf(dst, "Server: %s\n", "default");
54 fprintf(dst, "Address: %s\n\n", "default");
57 /* only works for IPv4 */
58 static int addr_fprint(char *addr, FILE * dst)
62 u_int32_t *x = (u_int32_t *) addr;
65 split[0] = (ip & 0xff000000) >> 24;
66 split[1] = (ip & 0x00ff0000) >> 16;
67 split[2] = (ip & 0x0000ff00) >> 8;
68 split[3] = (ip & 0x000000ff);
69 fprintf(dst, "%d.%d.%d.%d", split[0], split[1], split[2], split[3]
74 /* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
77 static u_int32_t str_to_addr(const char *addr)
82 sscanf(addr, "%d.%d.%d.%d",
83 &split[0], &split[1], &split[2], &split[3]);
85 /* assuming sscanf worked */
86 ip = (split[0] << 24) |
87 (split[1] << 16) | (split[2] << 8) | (split[3]);
92 /* takes the NULL-terminated array h_addr_list, and
93 * prints its contents appropriately
95 static int addr_list_fprint(char **h_addr_list, FILE * dst)
98 char *addr_string = (h_addr_list[1])
99 ? "Addresses: " : "Address: ";
101 fprintf(dst, "%s ", addr_string);
102 for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
103 addr_fprint(h_addr_list[i], dst);
105 /* real nslookup does this */
107 if (h_addr_list[i + 1]) {
112 if (h_addr_list[i + 1]) {
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 /* print the results as nslookup would */
132 static struct hostent *hostent_fprint(struct hostent *host, FILE * dst)
135 fprintf(dst, "Name: %s\n", host->h_name);
136 addr_list_fprint(host->h_addr_list, dst);
138 fprintf(dst, "*** %s\n", hstrerror(h_errno));
144 /* naive function to check whether char *s is an ip address */
145 static int is_ip_address(const char *s)
148 if ((isdigit(*s)) || (*s == '.')) {
157 /* ________________________________________________________________________ */
158 int nslookup_main(int argc, char **argv)
160 struct hostent *host;
162 if (argc < 2 || *argv[1]=='-') {
163 usage(nslookup_usage);
166 server_fprint(stdout);
167 if (is_ip_address(argv[1])) {
168 host = gethostbyaddr_wrapper(argv[1]);
170 host = gethostbyname(argv[1]);
172 hostent_fprint(host, stdout);
176 /* $Id: nslookup.c,v 1.7 2000/04/15 16:34:54 erik Exp $ */