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149 lines
4.1 KiB
C
149 lines
4.1 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini nslookup implementation for busybox
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*
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* Copyright (C) 1999,2000 by Lineo, inc. and John Beppu
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* Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
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*
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* Correct default name server display and explicit name server option
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* added by Ben Zeckel <bzeckel@hmc.edu> June 2001
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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#include <resolv.h>
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#include "busybox.h"
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/*
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* I'm only implementing non-interactive mode;
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* I totally forgot nslookup even had an interactive mode.
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*/
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/* Examples of 'standard' nslookup output
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* $ nslookup yahoo.com
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* Server: 128.193.0.10
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* Address: 128.193.0.10#53
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*
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* Non-authoritative answer:
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* Name: yahoo.com
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* Address: 216.109.112.135
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* Name: yahoo.com
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* Address: 66.94.234.13
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*
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* $ nslookup 204.152.191.37
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* Server: 128.193.4.20
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* Address: 128.193.4.20#53
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*
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* Non-authoritative answer:
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* 37.191.152.204.in-addr.arpa canonical name = 37.32-27.191.152.204.in-addr.arpa.
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* 37.32-27.191.152.204.in-addr.arpa name = zeus-pub2.kernel.org.
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*
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* Authoritative answers can be found from:
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* 32-27.191.152.204.in-addr.arpa nameserver = ns1.kernel.org.
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* 32-27.191.152.204.in-addr.arpa nameserver = ns2.kernel.org.
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* 32-27.191.152.204.in-addr.arpa nameserver = ns3.kernel.org.
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* ns1.kernel.org internet address = 140.211.167.34
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* ns2.kernel.org internet address = 204.152.191.4
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* ns3.kernel.org internet address = 204.152.191.36
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*/
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static int sockaddr_to_dotted(struct sockaddr *saddr, char *buf, int buflen)
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{
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if (buflen <= 0) return -1;
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buf[0] = '\0';
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if (saddr->sa_family == AF_INET) {
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inet_ntop(AF_INET, &((struct sockaddr_in*)saddr)->sin_addr, buf, buflen);
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return 0;
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}
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if (saddr->sa_family == AF_INET6) {
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inet_ntop(AF_INET6, &((struct sockaddr_in6*)saddr)->sin6_addr, buf, buflen);
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return 0;
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}
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return -1;
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}
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static int print_host(const char *hostname, const char *header)
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{
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char str[128]; /* IPv6 address will fit, hostnames hopefully too */
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struct addrinfo *result = NULL;
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int rc;
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struct addrinfo hint;
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memset(&hint, 0 , sizeof(hint));
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/* hint.ai_family = AF_UNSPEC; - zero anyway */
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/* Needed. Or else we will get each address thrice (or more)
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* for each possible socket type (tcp,udp,raw...): */
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hint.ai_socktype = SOCK_STREAM;
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// hint.ai_flags = AI_CANONNAME;
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rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result);
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if (!rc) {
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struct addrinfo *cur = result;
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// printf("%s\n", cur->ai_canonname); ?
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while (cur) {
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sockaddr_to_dotted(cur->ai_addr, str, sizeof(str));
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printf("%s %s\nAddress: %s", header, hostname, str);
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if (getnameinfo(cur->ai_addr, cur->ai_addrlen, str, sizeof(str), NULL, 0, NI_NAMEREQD))
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str[0] = '\0';
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printf(" %s\n", str);
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cur = cur->ai_next;
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}
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} else {
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bb_error_msg("getaddrinfo('%s') failed: %s", hostname, gai_strerror(rc));
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}
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freeaddrinfo(result);
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return (rc != 0);
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}
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/* alter the global _res nameserver structure to use
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an explicit dns server instead of what is in /etc/resolv.h */
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static void set_default_dns(char *server)
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{
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struct in_addr server_in_addr;
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if (inet_pton(AF_INET, server, &server_in_addr) > 0) {
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_res.nscount = 1;
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_res.nsaddr_list[0].sin_addr = server_in_addr;
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}
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}
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/* lookup the default nameserver and display it */
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static void server_print(void)
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{
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char str[INET6_ADDRSTRLEN];
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sockaddr_to_dotted((struct sockaddr*)&_res.nsaddr_list[0], str, sizeof(str));
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print_host(str, "Server:");
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puts("");
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}
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int nslookup_main(int argc, char **argv)
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{
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/*
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* initialize DNS structure _res used in printing the default
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* name server and in the explicit name server option feature.
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*/
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res_init();
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/*
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* We allow 1 or 2 arguments.
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* The first is the name to be looked up and the second is an
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* optional DNS server with which to do the lookup.
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* More than 3 arguments is an error to follow the pattern of the
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* standard nslookup
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*/
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if (argc < 2 || *argv[1] == '-' || argc > 3)
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bb_show_usage();
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else if(argc == 3)
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set_default_dns(argv[2]);
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server_print();
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return print_host(argv[1], "Name: ");
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}
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/* $Id: nslookup.c,v 1.33 2004/10/13 07:25:01 andersen Exp $ */
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