X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=networking%2Fnslookup.c;h=45c218e6c615947ee010ce4bec6a9fc1694ce05d;hb=ed4393bdc7a4d3b1b59293a3393eb1d6953bac99;hp=89a2d6481e45d7c5f78fe55f97b4e55b65b0d5d2;hpb=8528151658927bcb4822f2956b93d352cf5ad2e6;p=oweals%2Fbusybox.git diff --git a/networking/nslookup.c b/networking/nslookup.c index 89a2d6481..45c218e6c 100644 --- a/networking/nslookup.c +++ b/networking/nslookup.c @@ -8,22 +8,48 @@ * 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 tarball for details. + * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ +//config:config NSLOOKUP +//config: bool "nslookup (4.5 kb)" +//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 "busybox.h" +#include "libbb.h" /* - * I'm only implementing non-interactive mode; - * I totally forgot nslookup even had an interactive mode. + * 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 @@ -33,11 +59,11 @@ * $ 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. @@ -47,24 +73,10 @@ * 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 */ + /* We can't use xhost2sockaddr() - we want to get ALL addresses, + * not just one */ struct addrinfo *result = NULL; int rc; struct addrinfo hint; @@ -76,74 +88,122 @@ static int print_host(const char *hostname, const char *header) hint.ai_socktype = SOCK_STREAM; // hint.ai_flags = AI_CANONNAME; rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result); - if (!rc) { + + if (rc == 0) { struct addrinfo *cur = result; - // printf("%s\n", cur->ai_canonname); ? + unsigned cnt = 0; + + printf("%-10s %s\n", header, hostname); + // puts(cur->ai_canonname); ? while (cur) { - sockaddr_to_dotted(cur->ai_addr, str, sizeof(str)); - printf("%s %s\nAddress: %s", header, hostname, str); - s[0] = ' '; - if (getnameinfo(cur->ai_addr, cur->ai_addrlen, str+1, sizeof(str)-1, NULL, 0, NI_NAMEREQD)) - str[0] = '\0'; - puts(str); + 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 { - bb_error_msg("getaddrinfo('%s') failed: %s", hostname, gai_strerror(rc)); +#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 } - freeaddrinfo(result); + 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.h */ -static void set_default_dns(char *server) + an explicit dns server instead of what is in /etc/resolv.conf */ +static void set_default_dns(const 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; - } -} + len_and_sockaddr *lsa; + if (!server) + return; -/* lookup the default nameserver and display it */ -static void server_print(void) -{ - char str[INET6_ADDRSTRLEN]; + /* NB: this works even with, say, "[::1]:5353"! :) */ + lsa = xhost2sockaddr(server, 53); - sockaddr_to_dotted((struct sockaddr*)&_res.nsaddr_list[0], str, sizeof(str)); - print_host(str, "Server:"); - puts(""); + 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) { - /* - * initialize DNS structure _res used in printing the default - * name server and in the explicit name server option feature. - */ + /* 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;*/ - /* - * 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]); + set_default_dns(argv[2]); server_print(); - return print_host(argv[1], "Name: "); -} -/* $Id: nslookup.c,v 1.33 2004/10/13 07:25:01 andersen Exp $ */ + /* 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:"); +}