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nslookup: allow usage of IPv6 addresses or hostnames

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for DNS server name; allow for port specification.
 Tested to work: "nslookup google.com [::1]:5353"
This commit is contained in:
Denis Vlasenko 2008-11-16 19:02:26 +00:00
parent 5ff1265691
commit 3f5f246466
1 changed files with 26 additions and 11 deletions
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37
networking/nslookup.c
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@ -103,14 +103,15 @@ static int print_host(const char *hostname, const char *header)
static void server_print(void) static void server_print(void)
{ {
char *server; 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:"); print_host(server, "Server:");
if (ENABLE_FEATURE_CLEAN_UP) if (ENABLE_FEATURE_CLEAN_UP)
free(server); free(server);
@ -119,14 +120,28 @@ static void server_print(void)
/* alter the global _res nameserver structure to use /* alter the global _res nameserver structure to use
an explicit dns server instead of what is in /etc/resolv.conf */ 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.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; int nslookup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;