/*
* Mini nslookup implementation for busybox
*
- * Copyright (C) 2000 by Lineo, inc.
- * Written by John Beppu <beppu@lineo.com>
+ * Copyright (C) 1999,2000 by Lineo, inc. and John Beppu
+ * Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
*
- * 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 source tree.
*/
-#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>
+//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.
- |
- | [ TODO ]
- | + find out how to use non-default name servers
- | + find out how the real nslookup gets the default name server
- */
-
-static const char nslookup_usage[] = "nslookup [HOST]\n\nQueries the nameserver for the IP address of the given HOST\n";
-
-
-/* I have to see how the real nslookup does this.
- * I could dig through /etc/resolv.conf, but is there a
- * better (programatic) way?
+ * 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.
*/
-static void server_fprint(FILE * dst)
-{
- fprintf(dst, "Server: %s\n", "default");
- fprintf(dst, "Address: %s\n\n", "default");
-}
-/* only works for IPv4 */
-static int addr_fprint(char *addr, FILE * dst)
-{
- u_int8_t split[4];
- u_int32_t ip;
- u_int32_t *x = (u_int32_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;
-}
-
-/* changes a c-string matching the perl regex \d+\.\d+\.\d+\.\d+
- * into a u_int32_t
+/* 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 u_int32_t str_to_addr(const char *addr)
-{
- u_int32_t split[4];
- u_int32_t ip;
-
- sscanf(addr, "%d.%d.%d.%d",
- &split[0], &split[1], &split[2], &split[3]);
-
- /* assuming sscanf worked */
- ip = (split[0] << 24) |
- (split[1] << 16) | (split[2] << 8) | (split[3]);
- return htonl(ip);
-}
-
-/* takes the NULL-terminated array h_addr_list, and
- * prints its contents appropriately
- */
-static int addr_list_fprint(char **h_addr_list, FILE * dst)
+static int print_host(const char *hostname, const char *header)
{
- int i, j;
- char *addr_string = (h_addr_list[1])
- ? "Addresses: " : "Address: ";
-
- fprintf(dst, "%s ", addr_string);
- for (i = 0, j = 0; h_addr_list[i]; i++, j++) {
- addr_fprint(h_addr_list[i], dst);
-
- /* real nslookup does this */
- if (j == 4) {
- if (h_addr_list[i + 1]) {
- fprintf(dst, "\n ");
- }
- j = 0;
- } else {
- 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 == 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
}
- fprintf(dst, "\n");
- return 0;
+ if (ENABLE_FEATURE_CLEAN_UP && result)
+ freeaddrinfo(result);
+ return (rc != 0);
}
-/* gethostbyaddr wrapper */
-static struct hostent *gethostbyaddr_wrapper(const char *address)
+/* lookup the default nameserver and display it */
+static void server_print(void)
{
- struct in_addr addr;
-
- addr.s_addr = str_to_addr(address);
- return gethostbyaddr((char *) &addr, 4, AF_INET); /* IPv4 only for now */
+ 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');
}
-/* print the results as nslookup would */
-static struct hostent *hostent_fprint(struct hostent *host, FILE * dst)
+/* 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)
{
- if (host) {
- fprintf(dst, "Name: %s\n", host->h_name);
- addr_list_fprint(host->h_addr_list, dst);
- } else {
- fprintf(dst, "*** Unknown host\n");
- }
- return host;
-}
+ len_and_sockaddr *lsa;
+ if (!server)
+ return;
-/* naive function to check whether char *s is an ip address */
-static int is_ip_address(const char *s)
-{
- while (*s) {
- if ((isdigit(*s)) || (*s == '.')) {
- s++;
- continue;
- }
- return 0;
+ /* 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;
}
- return 1;
+#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)
{
- struct hostent *host;
-
- if (argc < 2 || *argv[1]=='-') {
- usage(nslookup_usage);
- }
-
- server_fprint(stdout);
- if (is_ip_address(argv[1])) {
- host = gethostbyaddr_wrapper(argv[1]);
- } else {
- host = gethostbyname(argv[1]);
- }
- hostent_fprint(host, stdout);
- exit( TRUE);
+ /* 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;*/
+
+ set_default_dns(argv[2]);
+
+ server_print();
+
+ /* getaddrinfo and friends are free to request a resolver
+ * reinitialization. Just in case, set_default_dns() again
+ * after getaddrinfo (in server_print). This reportedly helps
+ * with bug 675 "nslookup does not properly use second argument"
+ * at least on Debian Wheezy and Openwrt AA (eglibc based).
+ */
+ set_default_dns(argv[2]);
+
+ return print_host(argv[1], "Name:");
}
-
-/* $Id: nslookup.c,v 1.8 2000/05/02 00:07:56 erik Exp $ */
projects / platform / upstream / busybox.git / blobdiff