ares: Store dns parameters for duphandle

With ares the dns parameters lives in ares_channel. Store them in the
curl handle so we can set them again if we do easy_duphandle.

Closes curl#4893

Signed-off-by: Ernst Sjöstrand <ernst.sjostrand@verisure.com>

lib/asyn-ares.c

@@ -707,6 +707,7 @@ CURLcode Curl_set_dns_servers(struct Curl_easy *data,
   CURLcode result = CURLE_NOT_BUILT_IN;
   int ares_result;
 
+  Curl_safefree(data->dns_servers);
   /* If server is NULL or empty, this would purge all DNS servers
    * from ares library, which will cause any and all queries to fail.
    * So, just return OK if none are configured and don't actually make
@@ -717,6 +718,11 @@ CURLcode Curl_set_dns_servers(struct Curl_easy *data,
     return CURLE_OK;
 
 #if (ARES_VERSION >= 0x010704)
+  /* Make a copy of servers for any later duphandle */
+  data->dns_servers = strdup(servers);
+  if(!data->dns_servers)
+    return CURLE_OUT_OF_MEMORY;
+
 #if (ARES_VERSION >= 0x010b00)
   ares_result = ares_set_servers_ports_csv(data->state.resolver, servers);
 #else
@@ -747,6 +753,14 @@ CURLcode Curl_set_dns_interface(struct Curl_easy *data,
                                 const char *interf)
 {
 #if (ARES_VERSION >= 0x010704)
+  Curl_safefree(data->dns_interface);
+  if(interf) {
+    /* Make a copy of interface for any later duphandle */
+    data->dns_interface = strdup(interf);
+    if(!data->dns_interface)
+      return CURLE_OUT_OF_MEMORY;
+  }
+
   if(!interf)
     interf = "";
 
@@ -766,6 +780,14 @@ CURLcode Curl_set_dns_local_ip4(struct Curl_easy *data,
 #if (ARES_VERSION >= 0x010704)
   struct in_addr a4;
 
+  Curl_safefree(data->dns_local_ip4);
+  if(local_ip4) {
+    /* Make a copy of interface for any later duphandle */
+    data->dns_local_ip4 = strdup(local_ip4);
+    if(!data->dns_local_ip4)
+      return CURLE_OUT_OF_MEMORY;
+  }
+
   if((!local_ip4) || (local_ip4[0] == 0)) {
     a4.s_addr = 0; /* disabled: do not bind to a specific address */
   }
@@ -791,6 +813,14 @@ CURLcode Curl_set_dns_local_ip6(struct Curl_easy *data,
 #if (ARES_VERSION >= 0x010704) && defined(ENABLE_IPV6)
   unsigned char a6[INET6_ADDRSTRLEN];
 
+  Curl_safefree(data->dns_local_ip6);
+  if(local_ip6) {
+    /* Make a copy of interface for any later duphandle */
+    data->dns_local_ip6 = strdup(local_ip6);
+    if(!data->dns_local_ip6)
+      return CURLE_OUT_OF_MEMORY;
+  }
+
   if((!local_ip6) || (local_ip6[0] == 0)) {
     /* disabled: do not bind to a specific address */
     memset(a6, 0, sizeof(a6));

lib/easy.c

@@ -887,6 +887,17 @@ 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->dns_servers))
+    goto fail;
+  if(Curl_set_dns_interface(outcurl, data->dns_interface))
+    goto fail;
+  if(Curl_set_dns_local_ip4(outcurl, data->dns_local_ip4))
+    goto fail;
+  if(Curl_set_dns_local_ip6(outcurl, data->dns_local_ip6))
+    goto fail;
+#endif /* USE_ARES */
+
   Curl_convert_setup(outcurl);
 
   Curl_initinfo(outcurl);

lib/url.c

@@ -408,6 +408,13 @@ CURLcode Curl_close(struct Curl_easy **datap)
   curl_slist_free_all(data->req.doh.headers);
 #endif
 
+#ifdef USE_ARES
+  Curl_safefree(data->dns_servers);
+  Curl_safefree(data->dns_interface);
+  Curl_safefree(data->dns_local_ip4);
+  Curl_safefree(data->dns_local_ip6);
+#endif /* CURL_ARES */
+
   /* destruct wildcard structures if it is needed */
   Curl_wildcard_dtor(&data->wildcard);
   Curl_freeset(data);

lib/urldata.h

@@ -1916,6 +1916,12 @@ struct Curl_easy {
   iconv_t utf8_cd;             /* for translating to UTF8 */
 #endif /* CURL_DOES_CONVERSIONS && HAVE_ICONV */
   unsigned int magic;          /* set to a CURLEASY_MAGIC_NUMBER */
+#ifdef USE_ARES
+  char *dns_servers;
+  char *dns_interface;
+  char *dns_local_ip4;
+  char *dns_local_ip6;
+#endif /* USE_ARES */
 };
 
 #define LIBCURL_NAME "libcurl"