Annotation of /tags/mkinitrd-6_1_11/busybox/networking/nslookup.c
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Wed Oct 28 13:31:19 2009 UTC (14 years, 7 months ago) by niro
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Wed Oct 28 13:31:19 2009 UTC (14 years, 7 months ago) by niro
File MIME type: text/plain
File size: 4746 byte(s)
tagged 'mkinitrd-6_1_11'
1 | niro | 532 | /* 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 | niro | 816 | #include "libbb.h" |
16 | niro | 532 | |
17 | /* | ||
18 | niro | 816 | * 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 | niro | 532 | */ |
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 | niro | 816 | /* We can't use xhost2sockaddr() - we want to get ALL addresses, |
56 | * not just one */ | ||
57 | niro | 532 | 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 | niro | 816 | |
69 | niro | 532 | if (!rc) { |
70 | struct addrinfo *cur = result; | ||
71 | niro | 816 | unsigned cnt = 0; |
72 | |||
73 | printf("%-10s %s\n", header, hostname); | ||
74 | // puts(cur->ai_canonname); ? | ||
75 | niro | 532 | while (cur) { |
76 | niro | 816 | 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 | niro | 532 | cur = cur->ai_next; |
89 | } | ||
90 | } else { | ||
91 | niro | 816 | #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 | niro | 532 | } |
97 | niro | 816 | if (ENABLE_FEATURE_CLEAN_UP) |
98 | freeaddrinfo(result); | ||
99 | niro | 532 | return (rc != 0); |
100 | } | ||
101 | |||
102 | niro | 816 | /* lookup the default nameserver and display it */ |
103 | static void server_print(void) | ||
104 | { | ||
105 | char *server; | ||
106 | niro | 532 | |
107 | niro | 816 | 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) | ||
116 | free(server); | ||
117 | bb_putchar('\n'); | ||
118 | } | ||
119 | |||
120 | niro | 532 | /* alter the global _res nameserver structure to use |
121 | niro | 816 | an explicit dns server instead of what is in /etc/resolv.conf */ |
122 | niro | 532 | static void set_default_dns(char *server) |
123 | { | ||
124 | struct in_addr server_in_addr; | ||
125 | |||
126 | if (inet_pton(AF_INET, server, &server_in_addr) > 0) { | ||
127 | _res.nscount = 1; | ||
128 | _res.nsaddr_list[0].sin_addr = server_in_addr; | ||
129 | } | ||
130 | } | ||
131 | |||
132 | niro | 816 | int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
133 | niro | 532 | int nslookup_main(int argc, char **argv) |
134 | { | ||
135 | niro | 816 | /* 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) | ||
141 | bb_show_usage(); | ||
142 | niro | 532 | |
143 | niro | 816 | /* initialize DNS structure _res used in printing the default |
144 | * name server and in the explicit name server option feature. */ | ||
145 | niro | 532 | res_init(); |
146 | niro | 816 | /* rfc2133 says this enables IPv6 lookups */ |
147 | /* (but it also says "may be enabled in /etc/resolv.conf") */ | ||
148 | /*_res.options |= RES_USE_INET6;*/ | ||
149 | niro | 532 | |
150 | niro | 816 | if (argv[2]) |
151 | niro | 532 | set_default_dns(argv[2]); |
152 | |||
153 | server_print(); | ||
154 | niro | 816 | return print_host(argv[1], "Name:"); |
155 | niro | 532 | } |