retry resolve failure

repertory/librepertory/include/comm/curl/curl_comm.hpp

@@ -135,6 +135,8 @@ public:
                long &response_code, stop_type &stop_requested) -> bool {
     REPERTORY_USES_FUNCTION_NAME();
 
+    CURLcode curl_code{};
+    const auto do_request = [&]() -> bool {
       if (request.decryption_token.has_value() &&
           not request.decryption_token.value().empty()) {
         return make_encrypted_request(cfg, request, response_code,
@@ -213,7 +215,7 @@ public:
 
       multi_request curl_request(curl, stop_requested);
 
-    CURLcode curl_code{};
+      curl_code = CURLE_OK;
       curl_request.get_result(curl_code, response_code);
 
       if (header_list != nullptr) {
@@ -221,7 +223,8 @@ public:
       }
 
       if (curl_code != CURLE_OK) {
-      event_system::instance().raise<curl_error>(curl_code, function_name, url);
+        event_system::instance().raise<curl_error>(curl_code, function_name,
+                                                   url);
         return false;
       }
 
@@ -230,6 +233,24 @@ public:
       }
 
       return true;
+    };
+
+    bool ret{false};
+    for (std::uint8_t retry = 0U; !ret && retry < 5U; ++retry) {
+      ret = do_request();
+      if (ret) {
+        continue;
+      }
+
+      if (curl_code == CURLE_COULDNT_RESOLVE_HOST) {
+        std::this_thread::sleep_for(1s);
+        continue;
+      }
+
+      return ret;
+    }
+
+    return ret;
   }
 
 public: