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/* 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 tarball for details.
*/
#include <resolv.h>
#include "busybox.h"
/*
* I'm only implementing non-interactive mode;
* I totally forgot nslookup even had an interactive mode.
*/
/* 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 sockaddr_to_dotted(struct sockaddr *saddr, char *buf, int buflen)
{
if (buflen <= 0) return -1;
buf[0] = '\0';
if (saddr->sa_family == AF_INET) {
inet_ntop(AF_INET, &((struct sockaddr_in*)saddr)->sin_addr, buf, buflen);
return 0;
}
if (saddr->sa_family == AF_INET6) {
inet_ntop(AF_INET6, &((struct sockaddr_in6*)saddr)->sin6_addr, buf, buflen);
return 0;
}
return -1;
}
static int print_host(const char *hostname, const char *header)
{
char str[128]; /* IPv6 address will fit, hostnames hopefully too */
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) {
struct addrinfo *cur = result;
// printf("%s\n", cur->ai_canonname); ?
while (cur) {
sockaddr_to_dotted(cur->ai_addr, str, sizeof(str));
printf("%s %s\nAddress: %s", header, hostname, str);
str[0] = ' ';
if (getnameinfo(cur->ai_addr, cur->ai_addrlen, str+1, sizeof(str)-1, NULL, 0, NI_NAMEREQD))
str[0] = '\0';
puts(str);
cur = cur->ai_next;
}
} else {
bb_error_msg("getaddrinfo('%s') failed: %s", hostname, gai_strerror(rc));
}
freeaddrinfo(result);
return (rc != 0);
}
/* alter the global _res nameserver structure to use
an explicit dns server instead of what is in /etc/resolv.h */
static void set_default_dns(char *server)
{
struct in_addr server_in_addr;
if (inet_pton(AF_INET, server, &server_in_addr) > 0) {
_res.nscount = 1;
_res.nsaddr_list[0].sin_addr = server_in_addr;
}
}
/* lookup the default nameserver and display it */
static void server_print(void)
{
char str[INET6_ADDRSTRLEN];
sockaddr_to_dotted((struct sockaddr*)&_res.nsaddr_list[0], str, sizeof(str));
print_host(str, "Server:");
puts("");
}
int nslookup_main(int argc, char **argv)
{
/*
* initialize DNS structure _res used in printing the default
* name server and in the explicit name server option feature.
*/
res_init();
/*
* 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 (argc < 2 || *argv[1] == '-' || argc > 3)
bb_show_usage();
else if(argc == 3)
set_default_dns(argv[2]);
server_print();
return print_host(argv[1], "Name: ");
}
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