X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=networking%2Fnslookup.c;h=dd4b1ffedd29532813cf3827f983d40e6bcffdc2;hb=4967a41ba1d17090e764952975c651b22fd183d1;hp=424a0e4b97b809a6d4bf5ce5486191e86516f334;hpb=51742f4bb0c57a4d5063ece9437a2f34a42e52c8;p=oweals%2Fbusybox.git diff --git a/networking/nslookup.c b/networking/nslookup.c index 424a0e4b9..dd4b1ffed 100644 --- a/networking/nslookup.c +++ b/networking/nslookup.c @@ -8,15 +8,32 @@ * 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. */ +//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 @@ -51,7 +68,6 @@ static int print_host(const char *hostname, const char *header) { /* We can't use xhost2sockaddr() - we want to get ALL addresses, * not just one */ - struct addrinfo *result = NULL; int rc; struct addrinfo hint; @@ -64,16 +80,16 @@ static int print_host(const char *hostname, const char *header) // hint.ai_flags = AI_CANONNAME; rc = getaddrinfo(hostname, NULL /*service*/, &hint, &result); - if (!rc) { + if (rc == 0) { struct addrinfo *cur = result; unsigned cnt = 0; printf("%-10s %s\n", header, hostname); - // printf("%s\n", cur->ai_canonname); ? + // puts(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); + 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) { @@ -92,7 +108,7 @@ static int print_host(const char *hostname, const char *header) bb_error_msg("can't resolve '%s'", hostname); #endif } - if (ENABLE_FEATURE_CLEAN_UP) + if (ENABLE_FEATURE_CLEAN_UP && result) freeaddrinfo(result); return (rc != 0); } @@ -101,34 +117,56 @@ static int print_host(const char *hostname, const char *header) 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); - 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(""); + 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; + len_and_sockaddr *lsa; + + if (!server) + return; - if (inet_pton(AF_INET, server, &server_in_addr) > 0) { + /* NB: this works even with, say, "[::1]:5353"! :) */ + lsa = xhost2sockaddr(server, 53); + + if (lsa->u.sa.sa_family == AF_INET) { _res.nscount = 1; - _res.nsaddr_list[0].sin_addr = server_in_addr; + /* 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); +int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int nslookup_main(int argc, char **argv) { /* We allow 1 or 2 arguments. @@ -136,20 +174,27 @@ int nslookup_main(int argc, char **argv) * 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) + 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|) */ + /* (but it also says "may be enabled in /etc/resolv.conf") */ /*_res.options |= RES_USE_INET6;*/ - if (argc == 3) - set_default_dns(argv[2]); + 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:"); }