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    Contents of /trunk/mkinitrd-magellan/busybox/networking/nslookup.c

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    Revision 816 - (show annotations) (download)
    Fri Apr 24 18:33:46 2009 UTC (15 years, 1 month ago) by niro
    File MIME type: text/plain
    File size: 4746 byte(s) 
    -updated to busybox-1.13.4
    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
    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)
    116 free(server);
    117 bb_putchar('\n');
    118 }
    119
    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)
    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 int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
    133 int nslookup_main(int argc, char **argv)
    134 {
    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)
    141 bb_show_usage();
    142
    143 /* initialize DNS structure _res used in printing the default
    144 * name server and in the explicit name server option feature. */
    145 res_init();
    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;*/
    149
    150 if (argv[2])
    151 set_default_dns(argv[2]);
    152
    153 server_print();
    154 return print_host(argv[1], "Name:");
    155 }