From 3f5f24646656b761d2d50e57d778f41b13bffa11 Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Sun, 16 Nov 2008 19:02:26 +0000 Subject: [PATCH] nslookup: allow usage of IPv6 addresses or hostnames for DNS server name; allow for port specification. Tested to work: "nslookup google.com [::1]:5353" --- networking/nslookup.c | 37 ++++++++++++++++++++++++++----------- 1 file changed, 26 insertions(+), 11 deletions(-) diff --git a/networking/nslookup.c b/networking/nslookup.c index 73ccb0ddd..8a820ce37 100644 --- a/networking/nslookup.c +++ b/networking/nslookup.c @@ -103,14 +103,15 @@ 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]); - /* 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); @@ -119,14 +120,28 @@ static void server_print(void) /* 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(char *server) +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 +// Hoping libc will handle an IPv4 address there too, +// if it so happens that family is indeed AF_INET +// if (lsa->u.sa.sa_family == AF_INET6) { + _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;