+/* 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>
*
- * Copyright (C) 2000 by Lineo, inc.
- * Written by John Beppu <beppu@lineo.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * 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 "internal.h"
-#include <ctype.h>
-#include <errno.h>
-#include <stdio.h>
-#include <string.h>
-
-#include <netdb.h>
-#include <sys/socket.h>
-#include <sys/types.h>
-#include <netinet/in.h>
-
-
-static const char nslookup_usage[] =
-"only implementing non-interactive mode\n"
-"I totally forgot nslookup even had an interactive mode\n"
-;
-
-
-/* */
-static void
-server_fprint(FILE *dst)
-{
- fprintf(dst, "Server: %s\n", "something");
- fprintf(dst, "Address: %s\n\n", "something");
-}
-
-/* only works for IPv4 */
-static int
-addr_fprint(char *addr, FILE *dst)
-{
- uint8_t split[4];
- uint32_t ip;
- uint32_t *x = (uint32_t *) addr;
-
- ip = ntohl(*x);
- split[0] = (ip & 0xff000000) >> 24;
- split[1] = (ip & 0x00ff0000) >> 16;
- split[2] = (ip & 0x0000ff00) >> 8;
- split[3] = (ip & 0x000000ff);
- fprintf (
- dst, "%d.%d.%d.%d",
- split[0], split[1], split[2], split[3]
- );
- return 0;
-}
-
-/* */
-static uint32_t
-str_to_addr(const char *addr)
-{
- uint32_t split[4];
- uint32_t ip;
-
- sscanf(addr, "%d.%d.%d.%d",
- &split[0], &split[1], &split[2], &split[3]);
+#include <resolv.h>
+#include "libbb.h"
- /* assuming sscanf worked */
- ip = (split[0] << 24) |
- (split[1] << 16) |
- (split[2] << 8) |
- (split[3]);
+/*
+ * I'm only implementing non-interactive mode;
+ * I totally forgot nslookup even had an interactive mode.
+ */
- return htonl(ip);
-}
+/* 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
-addr_list_fprint(char **h_addr_list, FILE *dst)
+static int print_host(const char *hostname, const char *header)
{
- int i;
- char *addr_string = (h_addr_list[1])
- ? "Addresses"
- : "Address";
-
- fprintf(dst, "%s: ", addr_string);
- for (i = 0; h_addr_list[i]; i++) {
- addr_fprint(h_addr_list[i], dst);
- if (h_addr_list[i+1]) {
- fprintf(dst, ", ");
+ /* 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) {
+ struct addrinfo *cur = result;
+ unsigned cnt = 0;
+
+ printf("%-10s %s\n", header, hostname);
+ // printf("%s\n", cur->ai_canonname); ?
+ while (cur) {
+ char *dotted, *revhost;
+ dotted = xmalloc_sockaddr2dotted_noport(cur->ai_addr, cur->ai_addrlen);
+ revhost = xmalloc_sockaddr2hostonly_noport(cur->ai_addr, cur->ai_addrlen);
+
+ 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
}
- }
- fprintf(dst,"\n");
- return 0;
+ if (ENABLE_FEATURE_CLEAN_UP)
+ freeaddrinfo(result);
+ return (rc != 0);
}
-/* */
-static struct hostent *
-lookup_by_name(const char *hostname)
+/* lookup the default nameserver and display it */
+static void server_print(void)
{
- struct hostent *host;
-
- host = gethostbyname(hostname);
- if (host) {
- fprintf(stdout, "Name: %s\n", host->h_name);
- addr_list_fprint(host->h_addr_list, stdout);
- } else {
- herror("crap");
- }
- return host;
+ char *server;
+
+ server = xmalloc_sockaddr2dotted_noport((struct sockaddr*)&_res.nsaddr_list[0],
+ sizeof(struct sockaddr_in));
+ /* I honestly don't know what to do if DNS server has _IPv6 address_.
+ * Probably it is listed in
+ * _res._u._ext_.nsaddrs[MAXNS] (of type "struct sockaddr_in6*" each)
+ * but how to find out whether resolver uses
+ * _res.nsaddr_list[] or _res._u._ext_.nsaddrs[], or both?
+ * Looks like classic design from hell, BIND-grade. Hard to surpass. */
+ print_host(server, "Server:");
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(server);
+ puts("");
}
-/* */
-static struct hostent *
-lookup_by_addr(const char *addr)
+/* 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 hostent *host;
-
- host = gethostbyaddr(addr, 4, AF_INET); /* IPv4 only for now */
- if (host) {
- fprintf(stdout, "Name: %s\n", host->h_name);
- addr_list_fprint(host->h_addr_list, stdout);
- } else {
- herror("crap");
- }
- return host;
-}
+ struct in_addr server_in_addr;
-/* */
-static int
-is_ip_address(const char *s)
-{
- while (*s) {
- if ((isdigit(*s)) || (*s == '.')) { s++; continue; }
- return 0;
- }
- return 1;
+ if (inet_pton(AF_INET, server, &server_in_addr) > 0) {
+ _res.nscount = 1;
+ _res.nsaddr_list[0].sin_addr = server_in_addr;
+ }
}
-/* ________________________________________________________________________ */
-int
-nslookup_main(int argc, char **argv)
+int nslookup_main(int argc, char **argv);
+int nslookup_main(int argc, char **argv)
{
- struct in_addr addr;
-
- server_fprint(stdout);
- if (is_ip_address(argv[1])) {
- addr.s_addr = str_to_addr(argv[1]);
- lookup_by_addr((char *) &addr);
- } else {
- lookup_by_name(argv[1]);
- }
- return 0;
+ /* 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();
+
+ /* 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 (argc == 3)
+ set_default_dns(argv[2]);
+
+ server_print();
+ return print_host(argv[1], "Name:");
}
-
-/* $Id: nslookup.c,v 1.1 2000/01/29 12:59:01 beppu Exp $ */
projects / oweals / busybox.git / blobdiff