X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=networking%2Fnslookup.c;h=26287114caee6b83c1c01de0633048979872a329;hb=3b3ccdc5bc530e824a55ebc8d57c34f0ca6a30c9;hp=cc5ff95d69cf1044e544047da5c7433d6c93a749;hpb=067e3f031a2107c69d287d89b9543fbfe5c0a571;p=oweals%2Fbusybox.git diff --git a/networking/nslookup.c b/networking/nslookup.c index cc5ff95d6..26287114c 100644 --- a/networking/nslookup.c +++ b/networking/nslookup.c @@ -12,18 +12,21 @@ */ #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 +36,11 @@ * $ 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 +50,10 @@ * 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 +65,111 @@ 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) { 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); - str[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) + 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; + len_and_sockaddr *lsa; - 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 } - -/* lookup the default nameserver and display it */ -static void server_print(void) -{ - char str[INET6_ADDRSTRLEN]; - - sockaddr_to_dotted((struct sockaddr*)&_res.nsaddr_list[0], str, sizeof(str)); - print_host(str, "Server:"); - puts(""); -} - - +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) + if (argv[2]) set_default_dns(argv[2]); server_print(); - return print_host(argv[1], "Name: "); + return print_host(argv[1], "Name:"); } - -/* $Id: nslookup.c,v 1.33 2004/10/13 07:25:01 andersen Exp $ */