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.
18 * I'm only implementing non-interactive mode;
19 * I totally forgot nslookup even had an interactive mode.
22 /* Examples of 'standard' nslookup output
23 * $ nslookup yahoo.com
24 * Server: 128.193.0.10
25 * Address: 128.193.0.10#53
27 * Non-authoritative answer:
29 * Address: 216.109.112.135
31 * Address: 66.94.234.13
33 * $ nslookup 204.152.191.37
34 * Server: 128.193.4.20
35 * Address: 128.193.4.20#53
37 * Non-authoritative answer:
38 * 37.191.152.204.in-addr.arpa canonical name = 37.32-27.191.152.204.in-addr.arpa.
39 * 37.32-27.191.152.204.in-addr.arpa name = zeus-pub2.kernel.org.
41 * Authoritative answers can be found from:
42 * 32-27.191.152.204.in-addr.arpa nameserver = ns1.kernel.org.
43 * 32-27.191.152.204.in-addr.arpa nameserver = ns2.kernel.org.
44 * 32-27.191.152.204.in-addr.arpa nameserver = ns3.kernel.org.
45 * ns1.kernel.org internet address = 140.211.167.34
46 * ns2.kernel.org internet address = 204.152.191.4
47 * ns3.kernel.org internet address = 204.152.191.36
50 static int print_host(const char *hostname, const char *header)
52 /* We can't use xhost2sockaddr() - we want to get ALL addresses,
55 struct addrinfo *result = NULL;
59 memset(&hint, 0 , sizeof(hint));
60 /* hint.ai_family = AF_UNSPEC; - zero anyway */
61 /* Needed. Or else we will get each address thrice (or more)
62 * for each possible socket type (tcp,udp,raw...): */
63 hint.ai_socktype = SOCK_STREAM;
64 // hint.ai_flags = AI_CANONNAME;
65 rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result);
68 struct addrinfo *cur = result;
71 printf("%-10s %s\n", header, hostname);
72 // printf("%s\n", cur->ai_canonname); ?
74 char *dotted, *revhost;
75 dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr, cur->ai_addrlen);
76 revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr, cur->ai_addrlen);
78 printf("Address %u: %s%c", ++cnt, dotted, revhost ? ' ' : '\n');
81 if (ENABLE_FEATURE_CLEAN_UP)
84 if (ENABLE_FEATURE_CLEAN_UP)
89 #if ENABLE_VERBOSE_RESOLUTION_ERRORS
90 bb_error_msg("can't resolve '%s': %s", hostname, gai_strerror(rc));
92 bb_error_msg("can't resolve '%s'", hostname);
95 if (ENABLE_FEATURE_CLEAN_UP)
100 /* lookup the default nameserver and display it */
101 static void server_print(void)
105 server = xmalloc_sockaddr2dotted_noport((struct sockaddr*)&_res.nsaddr_list[0],
106 sizeof(struct sockaddr_in));
107 /* I honestly don't know what to do if DNS server has _IPv6 address_.
108 * Probably it is listed in
109 * _res._u._ext_.nsaddrs[MAXNS] (of type "struct sockaddr_in6*" each)
110 * but how to find out whether resolver uses
111 * _res.nsaddr_list[] or _res._u._ext_.nsaddrs[], or both?
112 * Looks like classic design from hell, BIND-grade. Hard to surpass. */
113 print_host(server, "Server:");
114 if (ENABLE_FEATURE_CLEAN_UP)
119 /* alter the global _res nameserver structure to use
120 an explicit dns server instead of what is in /etc/resolv.h */
121 static void set_default_dns(char *server)
123 struct in_addr server_in_addr;
125 if (inet_pton(AF_INET, server, &server_in_addr) > 0) {
127 _res.nsaddr_list[0].sin_addr = server_in_addr;
131 int nslookup_main(int argc, char **argv);
132 int nslookup_main(int argc, char **argv)
134 /* We allow 1 or 2 arguments.
135 * The first is the name to be looked up and the second is an
136 * optional DNS server with which to do the lookup.
137 * More than 3 arguments is an error to follow the pattern of the
138 * standard nslookup */
140 if (argc < 2 || *argv[1] == '-' || argc > 3)
143 /* initialize DNS structure _res used in printing the default
144 * name server and in the explicit name server option feature. */
146 /* rfc2133 says this enables IPv6 lookups */
147 /* (but it also says "may be enabled in /etc/resolv.conf|) */
148 /*_res.options |= RES_USE_INET6;*/
151 set_default_dns(argv[2]);
154 return print_host(argv[1], "Name:");