fix net.tcp.dns to enable selecting name server for zabbix-1.8.4

zabbix-1.8.4-fix_select_dns_nameserver.patch

diff -uNrp zabbix-1.8.4.orig/src/libs/zbxsysinfo/common/net.c zabbix-1.8.4/src/libs/zbxsysinfo/common/net.c
--- zabbix-1.8.4.orig/src/libs/zbxsysinfo/common/net.c	2011-01-04 22:57:50.000000000 +0900
+++ zabbix-1.8.4/src/libs/zbxsysinfo/common/net.c	2011-04-09 00:00:13.000000000 +0900
@@ -237,11 +237,6 @@ int	NET_TCP_DNS(const char *cmd, const c
                ip[0] = '\0';
         }
 
-	/* default parameter */
-	if(ip[0] == '\0')
-	{
-		strscpy(ip, "127.0.0.1");
-	}
 
 	if(get_param(param, 2, zone, MAX_STRING_LEN) != 0)
         {
@@ -254,15 +249,18 @@ int	NET_TCP_DNS(const char *cmd, const c
 		strscpy(zone, "localhost");
 	}
 
-	res = inet_aton(ip, &in);
-	if(res != 1)
-	{
-		SET_UI64_RESULT(result,0);
-		return SYSINFO_RET_FAIL;
-	}
-
 	if (!(_res.options & RES_INIT))
 		res_init();
+	/* default parameter */
+	if ('\0' != ip[0])
+	{
+		if (0 == inet_aton(ip, &in))
+			return SYSINFO_RET_FAIL;
+		_res.nsaddr_list[0].sin_addr = in;
+		_res.nsaddr_list[0].sin_family = AF_INET;
+		_res.nsaddr_list[0].sin_port = htons(NS_DEFAULTPORT);
+		_res.nscount = 1;
+	}
 
 	res = res_query(zone, C_IN, T_SOA, (unsigned char *)respbuf, sizeof(respbuf));