Bump to version 1.22.1

[platform/upstream/busybox.git] / networking / nslookup.c

diff --git a/networking/nslookup.c b/networking/nslookup.c
index 8a820ce..dd4b1ff 100644 (file)
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -8,9 +8,23 @@
  * Correct default name server display and explicit name server option
  * added by Ben Zeckel <bzeckel@hmc.edu> 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.
  */
 
+//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 <resolv.h>
 #include "libbb.h"
 
@@ -66,7 +80,7 @@ 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;
 
@@ -94,7 +108,7 @@ static int print_host(const char *hostname, const char *header)
                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);
 }
@@ -124,6 +138,9 @@ static void set_default_dns(const char *server)
 {
        len_and_sockaddr *lsa;
 
+       if (!server)
+               return;
+
        /* NB: this works even with, say, "[::1]:5353"! :) */
        lsa = xhost2sockaddr(server, 53);
 
@@ -133,14 +150,19 @@ static void set_default_dns(const char *server)
                _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) {
+       /* 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
 }
 
@@ -162,9 +184,17 @@ int nslookup_main(int argc, char **argv)
        /* (but it also says "may be enabled in /etc/resolv.conf") */
        /*_res.options |= RES_USE_INET6;*/
 
-       if (argv[2])
-               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:");
 }