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.
21 * This applet is the only user of res_init(). Without it,
22 * you may avoid pulling in _res global from libc.
25 /* Examples of 'standard' nslookup output
26 * $ nslookup yahoo.com
27 * Server: 128.193.0.10
28 * Address: 128.193.0.10#53
30 * Non-authoritative answer:
32 * Address: 216.109.112.135
34 * Address: 66.94.234.13
36 * $ nslookup 204.152.191.37
37 * Server: 128.193.4.20
38 * Address: 128.193.4.20#53
40 * Non-authoritative answer:
41 * 37.191.152.204.in-addr.arpa canonical name = 37.32-27.191.152.204.in-addr.arpa.
42 * 37.32-27.191.152.204.in-addr.arpa name = zeus-pub2.kernel.org.
44 * Authoritative answers can be found from:
45 * 32-27.191.152.204.in-addr.arpa nameserver = ns1.kernel.org.
46 * 32-27.191.152.204.in-addr.arpa nameserver = ns2.kernel.org.
47 * 32-27.191.152.204.in-addr.arpa nameserver = ns3.kernel.org.
48 * ns1.kernel.org internet address = 140.211.167.34
49 * ns2.kernel.org internet address = 204.152.191.4
50 * ns3.kernel.org internet address = 204.152.191.36
53 static int print_host(const char *hostname, const char *header)
55 /* We can't use xhost2sockaddr() - we want to get ALL addresses,
57 struct addrinfo *result = NULL;
61 memset(&hint, 0 , sizeof(hint));
62 /* hint.ai_family = AF_UNSPEC; - zero anyway */
63 /* Needed. Or else we will get each address thrice (or more)
64 * for each possible socket type (tcp,udp,raw...): */
65 hint.ai_socktype = SOCK_STREAM;
66 // hint.ai_flags = AI_CANONNAME;
67 rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result);
70 struct addrinfo *cur = result;
73 printf("%-10s %s\n", header, hostname);
74 // puts(cur->ai_canonname); ?
76 char *dotted, *revhost;
77 dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr);
78 revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr);
80 printf("Address %u: %s%c", ++cnt, dotted, revhost ? ' ' : '\n');
83 if (ENABLE_FEATURE_CLEAN_UP)
86 if (ENABLE_FEATURE_CLEAN_UP)
91 #if ENABLE_VERBOSE_RESOLUTION_ERRORS
92 bb_error_msg("can't resolve '%s': %s", hostname, gai_strerror(rc));
94 bb_error_msg("can't resolve '%s'", hostname);
97 if (ENABLE_FEATURE_CLEAN_UP)
102 /* lookup the default nameserver and display it */
103 static void server_print(void)
107 server = xmalloc_sockaddr2dotted_noport((struct sockaddr*)&_res.nsaddr_list[0]);
108 /* I honestly don't know what to do if DNS server has _IPv6 address_.
109 * Probably it is listed in
110 * _res._u._ext_.nsaddrs[MAXNS] (of type "struct sockaddr_in6*" each)
111 * but how to find out whether resolver uses
112 * _res.nsaddr_list[] or _res._u._ext_.nsaddrs[], or both?
113 * Looks like classic design from hell, BIND-grade. Hard to surpass. */
114 print_host(server, "Server:");
115 if (ENABLE_FEATURE_CLEAN_UP)
120 /* alter the global _res nameserver structure to use
121 an explicit dns server instead of what is in /etc/resolv.conf */
122 static void set_default_dns(char *server)
124 struct in_addr server_in_addr;
126 if (inet_pton(AF_INET, server, &server_in_addr) > 0) {
128 _res.nsaddr_list[0].sin_addr = server_in_addr;
132 int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
133 int nslookup_main(int argc, char **argv)
135 /* We allow 1 or 2 arguments.
136 * The first is the name to be looked up and the second is an
137 * optional DNS server with which to do the lookup.
138 * More than 3 arguments is an error to follow the pattern of the
139 * standard nslookup */
140 if (!argv[1] || argv[1][0] == '-' || 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:");