ares: store dns parameters for duphandle

With c-ares the dns parameters lives in ares_channel. Store them in the
curl handle and set them again in easy_duphandle.

Regression introduced in #3228 (6765e6d), shipped in curl 7.63.0.

Fixes #4893
Closes #5020
Signed-off-by: Ernst Sjöstrand <ernst.sjostrand@verisure.com>

lib/easy.c

@@ -883,6 +883,17 @@ struct Curl_easy *curl_easy_duphandle(struct Curl_easy *data)
                              data->state.resolver))
     goto fail;
 
+#ifdef USE_ARES
+  if(Curl_set_dns_servers(outcurl, data->set.str[STRING_DNS_SERVERS]))
+    goto fail;
+  if(Curl_set_dns_interface(outcurl, data->set.str[STRING_DNS_INTERFACE]))
+    goto fail;
+  if(Curl_set_dns_local_ip4(outcurl, data->set.str[STRING_DNS_LOCAL_IP4]))
+    goto fail;
+  if(Curl_set_dns_local_ip6(outcurl, data->set.str[STRING_DNS_LOCAL_IP6]))
+    goto fail;
+#endif /* USE_ARES */
+
   Curl_convert_setup(outcurl);
 
   Curl_initinfo(outcurl);

lib/setopt.c

@@ -2583,16 +2583,32 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
 #endif
 #ifdef USE_ARES
   case CURLOPT_DNS_SERVERS:
-    result = Curl_set_dns_servers(data, va_arg(param, char *));
+    result = Curl_setstropt(&data->set.str[STRING_DNS_SERVERS],
+                            va_arg(param, char *));
+    if(result)
+      return result;
+    result = Curl_set_dns_servers(data, data->set.str[STRING_DNS_SERVERS]);
     break;
   case CURLOPT_DNS_INTERFACE:
-    result = Curl_set_dns_interface(data, va_arg(param, char *));
+    result = Curl_setstropt(&data->set.str[STRING_DNS_INTERFACE],
+                            va_arg(param, char *));
+    if(result)
+      return result;
+    result = Curl_set_dns_interface(data, data->set.str[STRING_DNS_INTERFACE]);
     break;
   case CURLOPT_DNS_LOCAL_IP4:
-    result = Curl_set_dns_local_ip4(data, va_arg(param, char *));
+    result = Curl_setstropt(&data->set.str[STRING_DNS_LOCAL_IP4],
+                            va_arg(param, char *));
+    if(result)
+      return result;
+    result = Curl_set_dns_local_ip4(data, data->set.str[STRING_DNS_LOCAL_IP4]);
     break;
   case CURLOPT_DNS_LOCAL_IP6:
-    result = Curl_set_dns_local_ip6(data, va_arg(param, char *));
+    result = Curl_setstropt(&data->set.str[STRING_DNS_LOCAL_IP6],
+                            va_arg(param, char *));
+    if(result)
+      return result;
+    result = Curl_set_dns_local_ip6(data, data->set.str[STRING_DNS_LOCAL_IP6]);
     break;
 #endif
   case CURLOPT_TCP_KEEPALIVE:

lib/urldata.h

@@ -1577,6 +1577,11 @@ enum dupstring {
 
   STRING_TEMP_URL,              /* temp URL storage for proxy use */
 
+  STRING_DNS_SERVERS,
+  STRING_DNS_INTERFACE,
+  STRING_DNS_LOCAL_IP4,
+  STRING_DNS_LOCAL_IP6,
+
   /* -- end of zero-terminated strings -- */
 
   STRING_LASTZEROTERMINATED,
@@ -1585,6 +1590,7 @@ enum dupstring {
 
   STRING_COPYPOSTFIELDS,  /* if POST, set the fields' values here */
 
+
   STRING_LAST /* not used, just an end-of-list marker */
 };