fix libcurl problem with HTTP/2.0

Google DNS use HTTP/2.0 and some versions of libcurl fail to handle it correctly. Force libcurl to use HTTP/1.1 for now.
kamarya · Feb 8, 2020 · fe0ab2a · fe0ab2a
1 parent e3adc07
commit fe0ab2a
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Showing 2 changed files with 19 additions and 11 deletions.
diff --git a/inc/dnssec.h b/inc/dnssec.h
@@ -20,7 +20,7 @@
 
 #define PIDFILE             "/var/run/dnsd.pid"
 
-#define LICENSE             "DNSd  Copyright (C) 2016  Behrooz Kamary Aliabadi.\n"\
+#define LICENSE             "DNSd  Copyright (C) 2016  Behrooz Kamary.\n"\
                             "This program comes with ABSOLUTELY NO WARRANTY. \n"\
                             "You should have received a copy of the GNU General Public License\n"\
                             "along with this program. If not, see <http://www.gnu.org/licenses/>."

diff --git a/src/dnssec.c b/src/dnssec.c
@@ -153,7 +153,7 @@ size_t body_callback (void* contents, size_t size, size_t nmemb, void* userp)
     return chunk;
 }
 
-void https_query (struct dns_query* query)
+int https_query (struct dns_query* query)
 {
 
     CURL*     curl;
@@ -197,6 +197,10 @@ void https_query (struct dns_query* query)
         // do not check the SSL certificate authenticity
         //curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
         //curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);
+
+        // failed to work with libcurl/7.65.3 and HTTP/2.0
+        curl_easy_setopt(curl, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
+
         curl_easy_setopt(curl, CURLOPT_TIMEOUT, options.server_timeout);
 
         if (options.https_proxy[0])
@@ -211,17 +215,21 @@ void https_query (struct dns_query* query)
 
         res = curl_easy_perform(curl);
 
+        curl_easy_cleanup(curl);
+        curl_slist_free_all(headers);
+        LOG_DEBUG("curl_easy_perform() has returned.");
+
         if (res != CURLE_OK)
         {
             LOG_ERROR("curl_easy_perform() failed: %s", curl_easy_strerror(res));
+            return EXIT_FAILURE;
         }
-
-        curl_easy_cleanup(curl);
-        curl_slist_free_all(headers);
-        LOG_DEBUG("curl_easy_perform() has returned.");
+        return EXIT_SUCCESS;
     }
 
     curl_global_cleanup();
+
+    return EXIT_FAILURE;
 }
 
 int server()
@@ -351,11 +359,11 @@ int server()
         // TODO support multiple questions; however it seems others don't.
         if (ntohs(header->q_count) == 1)
         {
-            https_query(&query);
-
-            char* answer = (char *)(buffer + sizeof(struct dns_question) + sizeof(struct dns_header) + dnlen + 1);
-
-            answer_length = json_to_answer(answer, header, max_len);
+            if (https_query(&query) == EXIT_SUCCESS)
+            {
+                char* answer = (char *)(buffer + sizeof(struct dns_question) + sizeof(struct dns_header) + dnlen + 1);
+                answer_length = json_to_answer(answer, header, max_len);
+            }
         }
 
         if (!answer_length)