X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=networking%2Fnslookup.c;h=8e3c8fed9af02f79755c789001c2d285ef9a0f0f;hb=179e88bec91cfe58096900dc5509a080ff37b083;hp=62fea35fa6e8a437b8f878be94beb75d588d5b4e;hpb=5f825ee6d61df5496ede529d3cbf159531b7838d;p=oweals%2Fbusybox.git diff --git a/networking/nslookup.c b/networking/nslookup.c index 62fea35fa..8e3c8fed9 100644 --- a/networking/nslookup.c +++ b/networking/nslookup.c @@ -2,171 +2,208 @@ /* * Mini nslookup implementation for busybox * - * Copyright (C) 2000 by Lineo, inc. - * Written by John Beppu + * Copyright (C) 1999,2000 by Lineo, inc. and John Beppu + * Copyright (C) 1999,2000,2001 by John Beppu * - * 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 June 2001 * + * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ - -#include "busybox.h" -#include -#include -#include -#include - -#include -#include -#include -#include +//config:config NSLOOKUP +//config: bool "nslookup" +//config: default y +//config: help +//config: nslookup is a tool to query Internet name servers. + +//applet:IF_NSLOOKUP(APPLET(nslookup, BB_DIR_USR_BIN, BB_SUID_DROP)) + +//kbuild:lib-$(CONFIG_NSLOOKUP) += nslookup.o + +//usage:#define nslookup_trivial_usage +//usage: "[HOST] [SERVER]" +//usage:#define nslookup_full_usage "\n\n" +//usage: "Query the nameserver for the IP address of the given HOST\n" +//usage: "optionally using a specified DNS server" +//usage: +//usage:#define nslookup_example_usage +//usage: "$ 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 +#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 + * 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. */ -/* I have to see how the real nslookup does this. - * I could dig through /etc/resolv.conf, but is there a - * better (programatic) way? +/* 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 inline void server_fprint(void) -{ - printf("Server: %s\n", "default"); - printf("Address: %s\n\n", "default"); -} -/* only works for IPv4 */ -static int addr_fprint(char *addr) -{ - 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); - printf("%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 - */ -static u_int32_t str_to_addr(const char *addr) +static int print_host(const char *hostname, const char *header) { - 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) -{ - int i, j; - char *addr_string = (h_addr_list[1]) - ? "Addresses: " : "Address: "; - - printf("%s ", addr_string); - for (i = 0, j = 0; h_addr_list[i]; i++, j++) { - addr_fprint(h_addr_list[i]); - - /* real nslookup does this */ - if (j == 4) { - if (h_addr_list[i + 1]) { - printf("\n "); - } - j = 0; - } else { - if (h_addr_list[i + 1]) { - printf(", "); + /* 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 } - printf("\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) +/* 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) { - printf("Name: %s\n", host->h_name); - addr_list_fprint(host->h_addr_list); - } else { - printf("*** 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; + } +#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)! */ } - return 1; +#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(); - if (is_ip_address(argv[1])) { - host = gethostbyaddr_wrapper(argv[1]); - } else { - host = gethostbyname(argv[1]); - } - hostent_fprint(host); - return EXIT_SUCCESS; + /* 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 1.14 2001/01/20 16:22:58 andersen Exp $ */