blob: 202356b81a53db01e5d934669b06395d6102bd61
| 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 source tree. |
| 12 | */ |
| 13 | |
| 14 | //usage:#define nslookup_trivial_usage |
| 15 | //usage: "[HOST] [SERVER]" |
| 16 | //usage:#define nslookup_full_usage "\n\n" |
| 17 | //usage: "Query the nameserver for the IP address of the given HOST\n" |
| 18 | //usage: "optionally using a specified DNS server" |
| 19 | //usage: |
| 20 | //usage:#define nslookup_example_usage |
| 21 | //usage: "$ nslookup localhost\n" |
| 22 | //usage: "Server: default\n" |
| 23 | //usage: "Address: default\n" |
| 24 | //usage: "\n" |
| 25 | //usage: "Name: debian\n" |
| 26 | //usage: "Address: 127.0.0.1\n" |
| 27 | |
| 28 | #include <resolv.h> |
| 29 | #include "libbb.h" |
| 30 | |
| 31 | #ifdef ANDROID |
| 32 | # include <netinet/in.h> |
| 33 | # if ENABLE_FEATURE_IPV6 |
| 34 | # include <netinet/in6.h> |
| 35 | # endif |
| 36 | # define ANDROID_CHANGES |
| 37 | # ifdef BIONIC_L |
| 38 | # include <arpa/nameser.h> |
| 39 | # include <dns/include/resolv_private.h> |
| 40 | # include <dns/resolv/res_private.h> |
| 41 | # else |
| 42 | # include <arpa_nameser.h> |
| 43 | # include <private/resolv_private.h> |
| 44 | # include <netbsd/resolv/res_private.h> |
| 45 | # endif |
| 46 | |
| 47 | static struct __res_state res_st; |
| 48 | struct __res_state * __res_state(void) |
| 49 | { |
| 50 | return &res_st; |
| 51 | } |
| 52 | #endif |
| 53 | |
| 54 | #define EXT(res) ((&res)->_u._ext) |
| 55 | |
| 56 | /* |
| 57 | * I'm only implementing non-interactive mode; |
| 58 | * I totally forgot nslookup even had an interactive mode. |
| 59 | * |
| 60 | * This applet is the only user of res_init(). Without it, |
| 61 | * you may avoid pulling in _res global from libc. |
| 62 | */ |
| 63 | |
| 64 | /* Examples of 'standard' nslookup output |
| 65 | * $ nslookup yahoo.com |
| 66 | * Server: 128.193.0.10 |
| 67 | * Address: 128.193.0.10#53 |
| 68 | * |
| 69 | * Non-authoritative answer: |
| 70 | * Name: yahoo.com |
| 71 | * Address: 216.109.112.135 |
| 72 | * Name: yahoo.com |
| 73 | * Address: 66.94.234.13 |
| 74 | * |
| 75 | * $ nslookup 204.152.191.37 |
| 76 | * Server: 128.193.4.20 |
| 77 | * Address: 128.193.4.20#53 |
| 78 | * |
| 79 | * Non-authoritative answer: |
| 80 | * 37.191.152.204.in-addr.arpa canonical name = 37.32-27.191.152.204.in-addr.arpa. |
| 81 | * 37.32-27.191.152.204.in-addr.arpa name = zeus-pub2.kernel.org. |
| 82 | * |
| 83 | * Authoritative answers can be found from: |
| 84 | * 32-27.191.152.204.in-addr.arpa nameserver = ns1.kernel.org. |
| 85 | * 32-27.191.152.204.in-addr.arpa nameserver = ns2.kernel.org. |
| 86 | * 32-27.191.152.204.in-addr.arpa nameserver = ns3.kernel.org. |
| 87 | * ns1.kernel.org internet address = 140.211.167.34 |
| 88 | * ns2.kernel.org internet address = 204.152.191.4 |
| 89 | * ns3.kernel.org internet address = 204.152.191.36 |
| 90 | */ |
| 91 | |
| 92 | static int print_host(const char *hostname, const char *header) |
| 93 | { |
| 94 | /* We can't use xhost2sockaddr() - we want to get ALL addresses, |
| 95 | * not just one */ |
| 96 | struct addrinfo *result = NULL; |
| 97 | int rc; |
| 98 | struct addrinfo hint; |
| 99 | |
| 100 | memset(&hint, 0 , sizeof(hint)); |
| 101 | /* hint.ai_family = AF_UNSPEC; - zero anyway */ |
| 102 | /* Needed. Or else we will get each address thrice (or more) |
| 103 | * for each possible socket type (tcp,udp,raw...): */ |
| 104 | hint.ai_socktype = SOCK_STREAM; |
| 105 | // hint.ai_flags = AI_CANONNAME; |
| 106 | rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result); |
| 107 | |
| 108 | if (rc == 0) { |
| 109 | struct addrinfo *cur = result; |
| 110 | unsigned cnt = 0; |
| 111 | |
| 112 | printf("%-10s %s\n", header, hostname); |
| 113 | // puts(cur->ai_canonname); ? |
| 114 | while (cur) { |
| 115 | char *dotted, *revhost; |
| 116 | dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr); |
| 117 | revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr); |
| 118 | |
| 119 | printf("Address %u: %s%c", ++cnt, dotted, revhost ? ' ' : '\n'); |
| 120 | if (revhost) { |
| 121 | puts(revhost); |
| 122 | if (ENABLE_FEATURE_CLEAN_UP) |
| 123 | free(revhost); |
| 124 | } |
| 125 | if (ENABLE_FEATURE_CLEAN_UP) |
| 126 | free(dotted); |
| 127 | cur = cur->ai_next; |
| 128 | } |
| 129 | } else { |
| 130 | #if ENABLE_VERBOSE_RESOLUTION_ERRORS |
| 131 | bb_error_msg("can't resolve '%s': %s", hostname, gai_strerror(rc)); |
| 132 | #else |
| 133 | bb_error_msg("can't resolve '%s'", hostname); |
| 134 | #endif |
| 135 | } |
| 136 | if (ENABLE_FEATURE_CLEAN_UP && result) |
| 137 | freeaddrinfo(result); |
| 138 | return (rc != 0); |
| 139 | } |
| 140 | |
| 141 | /* lookup the default nameserver and display it */ |
| 142 | static void server_print(void) |
| 143 | { |
| 144 | char *server; |
| 145 | struct sockaddr *sa = NULL; |
| 146 | |
| 147 | #if ENABLE_FEATURE_IPV6 |
| 148 | # ifdef ANDROID |
| 149 | if (EXT(_res).ext) |
| 150 | sa = (struct sockaddr*) &EXT(_res).ext->nsaddrs[0]; |
| 151 | # else |
| 152 | sa = (struct sockaddr*)_res._u._ext.nsaddrs[0]; |
| 153 | # endif |
| 154 | |
| 155 | if (!sa) |
| 156 | #endif |
| 157 | sa = (struct sockaddr*) &_res.nsaddr_list[0]; |
| 158 | server = xmalloc_sockaddr2dotted_noport(sa); |
| 159 | |
| 160 | print_host(server, "Server:"); |
| 161 | if (ENABLE_FEATURE_CLEAN_UP) |
| 162 | free(server); |
| 163 | bb_putchar('\n'); |
| 164 | } |
| 165 | |
| 166 | /* alter the global _res nameserver structure to use |
| 167 | an explicit dns server instead of what is in /etc/resolv.conf */ |
| 168 | static void set_default_dns(const char *server) |
| 169 | { |
| 170 | len_and_sockaddr *lsa; |
| 171 | |
| 172 | if (!server) |
| 173 | return; |
| 174 | |
| 175 | /* NB: this works even with, say, "[::1]:53"! :) */ |
| 176 | lsa = xhost2sockaddr(server, 53); |
| 177 | |
| 178 | if (lsa->u.sa.sa_family == AF_INET) { |
| 179 | _res.nscount = 1; |
| 180 | /* struct copy */ |
| 181 | _res.nsaddr_list[0] = lsa->u.sin; |
| 182 | } |
| 183 | |
| 184 | #if ENABLE_FEATURE_IPV6 |
| 185 | /* Hoped libc can cope with IPv4 address there too. |
| 186 | * No such luck, glibc 2.4 segfaults even with IPv6, |
| 187 | * maybe I misunderstand how to make glibc use IPv6 addr? |
| 188 | * (uclibc 0.9.31+ should work) */ |
| 189 | if (lsa->u.sa.sa_family == AF_INET6) { |
| 190 | // glibc neither SEGVs nor sends any dgrams with this |
| 191 | // (strace shows no socket ops): |
| 192 | //_res.nscount = 0; |
| 193 | #ifdef ANDROID |
| 194 | if (EXT(_res).ext) { |
| 195 | EXT(_res).nscount = 1; |
| 196 | memcpy(&EXT(_res).ext->nsaddrs[0].sin6, &lsa->u.sin6, |
| 197 | sizeof(struct sockaddr_in6)); |
| 198 | } |
| 199 | #else |
| 200 | /* store a pointer to part of malloc'ed lsa */ |
| 201 | _res._u._ext.nscount = 1; |
| 202 | _res._u._ext.nsaddrs[0] = &lsa->u.sin6; |
| 203 | /* must not free(lsa)! */ |
| 204 | #endif |
| 205 | } |
| 206 | #endif |
| 207 | } |
| 208 | |
| 209 | int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| 210 | int nslookup_main(int argc, char **argv) |
| 211 | { |
| 212 | /* We allow 1 or 2 arguments. |
| 213 | * The first is the name to be looked up and the second is an |
| 214 | * optional DNS server with which to do the lookup. |
| 215 | * More than 3 arguments is an error to follow the pattern of the |
| 216 | * standard nslookup */ |
| 217 | if (!argv[1] || argv[1][0] == '-' || argc > 3) |
| 218 | bb_show_usage(); |
| 219 | |
| 220 | /* initialize DNS structure _res used in printing the default |
| 221 | * name server and in the explicit name server option feature. */ |
| 222 | res_init(); |
| 223 | |
| 224 | #ifdef ANDROID |
| 225 | res_ninit(&_res); |
| 226 | #endif |
| 227 | |
| 228 | /* rfc2133 says this enables IPv6 lookups */ |
| 229 | /* (but it also says "may be enabled in /etc/resolv.conf") */ |
| 230 | /*_res.options |= RES_USE_INET6;*/ |
| 231 | |
| 232 | set_default_dns(argv[2]); |
| 233 | |
| 234 | server_print(); |
| 235 | |
| 236 | /* getaddrinfo and friends are free to request a resolver |
| 237 | * reinitialization. Just in case, set_default_dns() again |
| 238 | * after getaddrinfo (in server_print). This reportedly helps |
| 239 | * with bug 675 "nslookup does not properly use second argument" |
| 240 | * at least on Debian Wheezy and Openwrt AA (eglibc based). |
| 241 | */ |
| 242 | set_default_dns(argv[2]); |
| 243 | |
| 244 | return print_host(argv[1], "Name:"); |
| 245 | } |
| 246 |