5bc8c005a8
Signed-off-by: Pere Orga <gotrunks@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
190 lines
5.5 KiB
C
190 lines
5.5 KiB
C
/* vi: set sw=4 ts=4: */
|
|
/*
|
|
* Mini nslookup implementation for busybox
|
|
*
|
|
* Copyright (C) 1999,2000 by Lineo, inc. and John Beppu
|
|
* Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
|
|
*
|
|
* Correct default name server display and explicit name server option
|
|
* added by Ben Zeckel <bzeckel@hmc.edu> June 2001
|
|
*
|
|
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
|
|
*/
|
|
|
|
//usage:#define nslookup_trivial_usage
|
|
//usage: "[HOST] [SERVER]"
|
|
//usage:#define nslookup_full_usage "\n\n"
|
|
//usage: "Query the nameserver for the IP address of the given HOST\n"
|
|
//usage: "optionally using a specified DNS server"
|
|
//usage:
|
|
//usage:#define nslookup_example_usage
|
|
//usage: "$ nslookup localhost\n"
|
|
//usage: "Server: default\n"
|
|
//usage: "Address: default\n"
|
|
//usage: "\n"
|
|
//usage: "Name: debian\n"
|
|
//usage: "Address: 127.0.0.1\n"
|
|
|
|
#include <resolv.h>
|
|
#include "libbb.h"
|
|
|
|
/*
|
|
* I'm only implementing non-interactive mode;
|
|
* I totally forgot nslookup even had an interactive mode.
|
|
*
|
|
* This applet is the only user of res_init(). Without it,
|
|
* you may avoid pulling in _res global from libc.
|
|
*/
|
|
|
|
/* Examples of 'standard' nslookup output
|
|
* $ nslookup yahoo.com
|
|
* Server: 128.193.0.10
|
|
* Address: 128.193.0.10#53
|
|
*
|
|
* Non-authoritative answer:
|
|
* Name: yahoo.com
|
|
* Address: 216.109.112.135
|
|
* Name: yahoo.com
|
|
* Address: 66.94.234.13
|
|
*
|
|
* $ nslookup 204.152.191.37
|
|
* Server: 128.193.4.20
|
|
* Address: 128.193.4.20#53
|
|
*
|
|
* Non-authoritative answer:
|
|
* 37.191.152.204.in-addr.arpa canonical name = 37.32-27.191.152.204.in-addr.arpa.
|
|
* 37.32-27.191.152.204.in-addr.arpa name = zeus-pub2.kernel.org.
|
|
*
|
|
* Authoritative answers can be found from:
|
|
* 32-27.191.152.204.in-addr.arpa nameserver = ns1.kernel.org.
|
|
* 32-27.191.152.204.in-addr.arpa nameserver = ns2.kernel.org.
|
|
* 32-27.191.152.204.in-addr.arpa nameserver = ns3.kernel.org.
|
|
* ns1.kernel.org internet address = 140.211.167.34
|
|
* ns2.kernel.org internet address = 204.152.191.4
|
|
* ns3.kernel.org internet address = 204.152.191.36
|
|
*/
|
|
|
|
static int print_host(const char *hostname, const char *header)
|
|
{
|
|
/* We can't use xhost2sockaddr() - we want to get ALL addresses,
|
|
* not just one */
|
|
struct addrinfo *result = NULL;
|
|
int rc;
|
|
struct addrinfo hint;
|
|
|
|
memset(&hint, 0 , sizeof(hint));
|
|
/* hint.ai_family = AF_UNSPEC; - zero anyway */
|
|
/* Needed. Or else we will get each address thrice (or more)
|
|
* for each possible socket type (tcp,udp,raw...): */
|
|
hint.ai_socktype = SOCK_STREAM;
|
|
// hint.ai_flags = AI_CANONNAME;
|
|
rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result);
|
|
|
|
if (rc == 0) {
|
|
struct addrinfo *cur = result;
|
|
unsigned cnt = 0;
|
|
|
|
printf("%-10s %s\n", header, hostname);
|
|
// puts(cur->ai_canonname); ?
|
|
while (cur) {
|
|
char *dotted, *revhost;
|
|
dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr);
|
|
revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr);
|
|
|
|
printf("Address %u: %s%c", ++cnt, dotted, revhost ? ' ' : '\n');
|
|
if (revhost) {
|
|
puts(revhost);
|
|
if (ENABLE_FEATURE_CLEAN_UP)
|
|
free(revhost);
|
|
}
|
|
if (ENABLE_FEATURE_CLEAN_UP)
|
|
free(dotted);
|
|
cur = cur->ai_next;
|
|
}
|
|
} else {
|
|
#if ENABLE_VERBOSE_RESOLUTION_ERRORS
|
|
bb_error_msg("can't resolve '%s': %s", hostname, gai_strerror(rc));
|
|
#else
|
|
bb_error_msg("can't resolve '%s'", hostname);
|
|
#endif
|
|
}
|
|
if (ENABLE_FEATURE_CLEAN_UP && result)
|
|
freeaddrinfo(result);
|
|
return (rc != 0);
|
|
}
|
|
|
|
/* lookup the default nameserver and display it */
|
|
static void server_print(void)
|
|
{
|
|
char *server;
|
|
struct sockaddr *sa;
|
|
|
|
#if ENABLE_FEATURE_IPV6
|
|
sa = (struct sockaddr*)_res._u._ext.nsaddrs[0];
|
|
if (!sa)
|
|
#endif
|
|
sa = (struct sockaddr*)&_res.nsaddr_list[0];
|
|
server = xmalloc_sockaddr2dotted_noport(sa);
|
|
|
|
print_host(server, "Server:");
|
|
if (ENABLE_FEATURE_CLEAN_UP)
|
|
free(server);
|
|
bb_putchar('\n');
|
|
}
|
|
|
|
/* alter the global _res nameserver structure to use
|
|
an explicit dns server instead of what is in /etc/resolv.conf */
|
|
static void set_default_dns(const char *server)
|
|
{
|
|
len_and_sockaddr *lsa;
|
|
|
|
/* NB: this works even with, say, "[::1]:5353"! :) */
|
|
lsa = xhost2sockaddr(server, 53);
|
|
|
|
if (lsa->u.sa.sa_family == AF_INET) {
|
|
_res.nscount = 1;
|
|
/* struct copy */
|
|
_res.nsaddr_list[0] = lsa->u.sin;
|
|
}
|
|
#if ENABLE_FEATURE_IPV6
|
|
/* Hoped libc can cope with IPv4 address there too.
|
|
* No such luck, glibc 2.4 segfaults even with IPv6,
|
|
* maybe I misunderstand how to make glibc use IPv6 addr?
|
|
* (uclibc 0.9.31+ should work) */
|
|
if (lsa->u.sa.sa_family == AF_INET6) {
|
|
// glibc neither SEGVs nor sends any dgrams with this
|
|
// (strace shows no socket ops):
|
|
//_res.nscount = 0;
|
|
_res._u._ext.nscount = 1;
|
|
/* store a pointer to part of malloc'ed lsa */
|
|
_res._u._ext.nsaddrs[0] = &lsa->u.sin6;
|
|
/* must not free(lsa)! */
|
|
}
|
|
#endif
|
|
}
|
|
|
|
int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
|
int nslookup_main(int argc, char **argv)
|
|
{
|
|
/* We allow 1 or 2 arguments.
|
|
* The first is the name to be looked up and the second is an
|
|
* optional DNS server with which to do the lookup.
|
|
* More than 3 arguments is an error to follow the pattern of the
|
|
* standard nslookup */
|
|
if (!argv[1] || argv[1][0] == '-' || argc > 3)
|
|
bb_show_usage();
|
|
|
|
/* initialize DNS structure _res used in printing the default
|
|
* name server and in the explicit name server option feature. */
|
|
res_init();
|
|
/* rfc2133 says this enables IPv6 lookups */
|
|
/* (but it also says "may be enabled in /etc/resolv.conf") */
|
|
/*_res.options |= RES_USE_INET6;*/
|
|
|
|
if (argv[2])
|
|
set_default_dns(argv[2]);
|
|
|
|
server_print();
|
|
return print_host(argv[1], "Name:");
|
|
}
|