3f5f24646
Denis Vlasenko
2008-11-16
Subject
nslookup: allow usage of IPv6 addresses or hostnames for DNS server name; allow for port specification. Tested to work: "nslookup google.com [::1]:5353"
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Commit Diff GitHub →
networking/nslookup.c+26 -11
| @@ -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; | |