X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=networking%2Fnslookup.c;h=8e3c8fed9af02f79755c789001c2d285ef9a0f0f;hb=179e88bec91cfe58096900dc5509a080ff37b083;hp=af0816215e95e54cd1ec3ba9411fddc51db3aca1;hpb=448f0241e06e7df2003b7f8afcf01e7406762b4e;p=oweals%2Fbusybox.git diff --git a/networking/nslookup.c b/networking/nslookup.c index af0816215..8e3c8fed9 100644 --- a/networking/nslookup.c +++ b/networking/nslookup.c @@ -8,15 +8,41 @@ * 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" +//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 @@ -47,60 +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) { -#if 0 - char str[128]; /* IPv6 address will fit, hostnames hopefully too */ - 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; - // printf("%s\n", cur->ai_canonname); ? - while (cur) { - sockaddr_to_dotted(cur->ai_addr, str, sizeof(str)); - printf("%s %s\nAddress: %s", header, hostname, str); - str[0] = ' '; - if (getnameinfo(cur->ai_addr, cur->ai_addrlen, str+1, sizeof(str)-1, NULL, 0, NI_NAMEREQD)) - str[0] = '\0'; - puts(str); - cur = cur->ai_next; - } - } else { - bb_error_msg("getaddrinfo('%s') failed: %s", hostname, gai_strerror(rc)); - } - freeaddrinfo(result); - return (rc != 0); - -#else - /* We can't use host2sockaddr() - we want to get ALL addresses, + /* We can't use xhost2sockaddr() - we want to get ALL addresses, * not just one */ - struct addrinfo *result = NULL; int rc; struct addrinfo hint; @@ -113,16 +89,16 @@ 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) { @@ -136,51 +112,70 @@ static int print_host(const char *hostname, const char *header) } } else { #if ENABLE_VERBOSE_RESOLUTION_ERRORS - bb_error_msg("getaddrinfo('%s') failed: %s", hostname, gai_strerror(rc)); + bb_error_msg("can't resolve '%s': %s", hostname, gai_strerror(rc)); #else 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); -#endif } - /* 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); - 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) MAIN_EXTERNALLY_VISIBLE; int nslookup_main(int argc, char **argv) { /* We allow 1 or 2 arguments. @@ -188,20 +183,27 @@ 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:"); }