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 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
22 #include <sys/socket.h>
23 #include <sys/types.h>
24 #include <netinet/in.h>
26 #include <arpa/inet.h>
30 | I'm only implementing non-interactive mode;
31 | I totally forgot nslookup even had an interactive mode.
34 /* only works for IPv4 */
35 static int addr_fprint(char *addr)
39 uint32_t *x = (uint32_t *) addr;
42 split[0] = (ip & 0xff000000) >> 24;
43 split[1] = (ip & 0x00ff0000) >> 16;
44 split[2] = (ip & 0x0000ff00) >> 8;
45 split[3] = (ip & 0x000000ff);
46 printf("%d.%d.%d.%d", split[0], split[1], split[2], split[3]);
50 /* takes the NULL-terminated array h_addr_list, and
51 * prints its contents appropriately
53 static int addr_list_fprint(char **h_addr_list)
56 char *addr_string = (h_addr_list[1])
57 ? "Addresses: " : "Address: ";
59 printf("%s ", addr_string);
60 for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
61 addr_fprint(h_addr_list[i]);
63 /* real nslookup does this */
65 if (h_addr_list[i + 1]) {
70 if (h_addr_list[i + 1]) {
80 /* print the results as nslookup would */
81 static struct hostent *hostent_fprint(struct hostent *host, const char *server_host)
84 printf("%s %s\n", server_host, host->h_name);
85 addr_list_fprint(host->h_addr_list);
87 printf("*** Unknown host\n");
92 /* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
95 static uint32_t str_to_addr(const char *addr)
100 sscanf(addr, "%d.%d.%d.%d",
101 &split[0], &split[1], &split[2], &split[3]);
103 /* assuming sscanf worked */
104 ip = (split[0] << 24) |
105 (split[1] << 16) | (split[2] << 8) | (split[3]);
110 /* gethostbyaddr wrapper */
111 static struct hostent *gethostbyaddr_wrapper(const char *address)
115 addr.s_addr = str_to_addr(address);
116 return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */
119 /* lookup the default nameserver and display it */
120 static inline void server_print(void)
122 struct sockaddr_in def = _res.nsaddr_list[0];
123 char *ip = inet_ntoa(def.sin_addr);
125 hostent_fprint(gethostbyaddr_wrapper(ip), "Server:");
129 /* alter the global _res nameserver structure to use
130 an explicit dns server instead of what is in /etc/resolv.h */
131 static inline void set_default_dns(char *server)
133 struct in_addr server_in_addr;
135 if(inet_aton(server,&server_in_addr))
138 _res.nsaddr_list[0].sin_addr = server_in_addr;
142 /* naive function to check whether char *s is an ip address */
143 static int is_ip_address(const char *s)
146 if ((isdigit(*s)) || (*s == '.')) {
155 /* ________________________________________________________________________ */
156 int nslookup_main(int argc, char **argv)
158 struct hostent *host;
161 * initialize DNS structure _res used in printing the default
162 * name server and in the explicit name server option feature.
168 * We allow 1 or 2 arguments.
169 * The first is the name to be looked up and the second is an
170 * optional DNS server with which to do the lookup.
171 * More than 3 arguments is an error to follow the pattern of the
175 if (argc < 2 || *argv[1]=='-' || argc > 3)
178 set_default_dns(argv[2]);
181 if (is_ip_address(argv[1])) {
182 host = gethostbyaddr_wrapper(argv[1]);
184 host = xgethostbyname(argv[1]);
186 hostent_fprint(host, "Name: ");
193 /* $Id: nslookup.c,v 1.33 2004/10/13 07:25:01 andersen Exp $ */