Contents of /tags/mkinitrd-6_3_4/busybox/networking/nslookup.c
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Thu Dec 16 01:27:43 2010 UTC (13 years, 9 months ago) by niro
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Thu Dec 16 01:27:43 2010 UTC (13 years, 9 months ago) by niro
File MIME type: text/plain
File size: 5135 byte(s)
tagged 'mkinitrd-6_3_4'
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Mini nslookup implementation for busybox |
4 | * |
5 | * Copyright (C) 1999,2000 by Lineo, inc. and John Beppu |
6 | * Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org> |
7 | * |
8 | * Correct default name server display and explicit name server option |
9 | * added by Ben Zeckel <bzeckel@hmc.edu> June 2001 |
10 | * |
11 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
12 | */ |
13 | |
14 | #include <resolv.h> |
15 | #include "libbb.h" |
16 | |
17 | /* |
18 | * I'm only implementing non-interactive mode; |
19 | * I totally forgot nslookup even had an interactive mode. |
20 | * |
21 | * This applet is the only user of res_init(). Without it, |
22 | * you may avoid pulling in _res global from libc. |
23 | */ |
24 | |
25 | /* Examples of 'standard' nslookup output |
26 | * $ nslookup yahoo.com |
27 | * Server: 128.193.0.10 |
28 | * Address: 128.193.0.10#53 |
29 | * |
30 | * Non-authoritative answer: |
31 | * Name: yahoo.com |
32 | * Address: 216.109.112.135 |
33 | * Name: yahoo.com |
34 | * Address: 66.94.234.13 |
35 | * |
36 | * $ nslookup 204.152.191.37 |
37 | * Server: 128.193.4.20 |
38 | * Address: 128.193.4.20#53 |
39 | * |
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. |
43 | * |
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 |
51 | */ |
52 | |
53 | static int print_host(const char *hostname, const char *header) |
54 | { |
55 | /* We can't use xhost2sockaddr() - we want to get ALL addresses, |
56 | * not just one */ |
57 | struct addrinfo *result = NULL; |
58 | int rc; |
59 | struct addrinfo hint; |
60 | |
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); |
68 | |
69 | if (!rc) { |
70 | struct addrinfo *cur = result; |
71 | unsigned cnt = 0; |
72 | |
73 | printf("%-10s %s\n", header, hostname); |
74 | // puts(cur->ai_canonname); ? |
75 | while (cur) { |
76 | char *dotted, *revhost; |
77 | dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr); |
78 | revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr); |
79 | |
80 | printf("Address %u: %s%c", ++cnt, dotted, revhost ? ' ' : '\n'); |
81 | if (revhost) { |
82 | puts(revhost); |
83 | if (ENABLE_FEATURE_CLEAN_UP) |
84 | free(revhost); |
85 | } |
86 | if (ENABLE_FEATURE_CLEAN_UP) |
87 | free(dotted); |
88 | cur = cur->ai_next; |
89 | } |
90 | } else { |
91 | #if ENABLE_VERBOSE_RESOLUTION_ERRORS |
92 | bb_error_msg("can't resolve '%s': %s", hostname, gai_strerror(rc)); |
93 | #else |
94 | bb_error_msg("can't resolve '%s'", hostname); |
95 | #endif |
96 | } |
97 | if (ENABLE_FEATURE_CLEAN_UP) |
98 | freeaddrinfo(result); |
99 | return (rc != 0); |
100 | } |
101 | |
102 | /* lookup the default nameserver and display it */ |
103 | static void server_print(void) |
104 | { |
105 | char *server; |
106 | struct sockaddr *sa; |
107 | |
108 | #if ENABLE_FEATURE_IPV6 |
109 | sa = (struct sockaddr*)_res._u._ext.nsaddrs[0]; |
110 | if (!sa) |
111 | #endif |
112 | sa = (struct sockaddr*)&_res.nsaddr_list[0]; |
113 | server = xmalloc_sockaddr2dotted_noport(sa); |
114 | |
115 | print_host(server, "Server:"); |
116 | if (ENABLE_FEATURE_CLEAN_UP) |
117 | free(server); |
118 | bb_putchar('\n'); |
119 | } |
120 | |
121 | /* alter the global _res nameserver structure to use |
122 | an explicit dns server instead of what is in /etc/resolv.conf */ |
123 | static void set_default_dns(const char *server) |
124 | { |
125 | len_and_sockaddr *lsa; |
126 | |
127 | /* NB: this works even with, say, "[::1]:5353"! :) */ |
128 | lsa = xhost2sockaddr(server, 53); |
129 | |
130 | if (lsa->u.sa.sa_family == AF_INET) { |
131 | _res.nscount = 1; |
132 | /* struct copy */ |
133 | _res.nsaddr_list[0] = lsa->u.sin; |
134 | } |
135 | #if ENABLE_FEATURE_IPV6 |
136 | /* Hoped libc can cope with IPv4 address there too. |
137 | * No such luck, glibc 2.4 segfaults even with IPv6, |
138 | * maybe I misunderstand how to make glibc use IPv6 addr? |
139 | * (uclibc 0.9.31+ should work) */ |
140 | if (lsa->u.sa.sa_family == AF_INET6) { |
141 | // glibc neither SEGVs nor sends any dgrams with this |
142 | // (strace shows no socket ops): |
143 | //_res.nscount = 0; |
144 | _res._u._ext.nscount = 1; |
145 | /* store a pointer to part of malloc'ed lsa */ |
146 | _res._u._ext.nsaddrs[0] = &lsa->u.sin6; |
147 | /* must not free(lsa)! */ |
148 | } |
149 | #endif |
150 | } |
151 | |
152 | int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
153 | int nslookup_main(int argc, char **argv) |
154 | { |
155 | /* We allow 1 or 2 arguments. |
156 | * The first is the name to be looked up and the second is an |
157 | * optional DNS server with which to do the lookup. |
158 | * More than 3 arguments is an error to follow the pattern of the |
159 | * standard nslookup */ |
160 | if (!argv[1] || argv[1][0] == '-' || argc > 3) |
161 | bb_show_usage(); |
162 | |
163 | /* initialize DNS structure _res used in printing the default |
164 | * name server and in the explicit name server option feature. */ |
165 | res_init(); |
166 | /* rfc2133 says this enables IPv6 lookups */ |
167 | /* (but it also says "may be enabled in /etc/resolv.conf") */ |
168 | /*_res.options |= RES_USE_INET6;*/ |
169 | |
170 | if (argv[2]) |
171 | set_default_dns(argv[2]); |
172 | |
173 | server_print(); |
174 | return print_host(argv[1], "Name:"); |
175 | } |