proxy_server: set expiration for iOS devices

At this point we do not care for the request. Subscribes are
instantaneous, so the request will be terminated at this point.
Changing the stop status can cause some push notifications to be
dropped if coming at this moment.

src/dht_proxy_client.cpp

@@ -1265,11 +1265,7 @@ DhtProxyClient::resubscribe(const InfoHash& key, const size_t token, Listener& l
         logger_->d("[proxy:client] [resubscribe] [search %s]", key.to_c_str());
 
     auto opstate = listener.opstate;
-    opstate->stop = true;
-    if (listener.request){
-        listener.request.reset();
-    }
-    opstate->stop = false;
+    listener.request.reset(); // This will update ok to false
     opstate->ok = true;
 
     restinio::http_request_header_t header;

src/dht_proxy_server.cpp

@@ -1004,7 +1004,13 @@ DhtProxyServer::sendPushNotification(const std::string& token, Json::Value&& jso
         notification["platform"] = type == PushType::Android ? 2 : 1;
         notification["data"] = std::move(json);
         notification["priority"] = highPriority ? "high" : "normal";
-        notification["time_to_live"] = 600;
+        if (type == PushType::Android)
+            notification["time_to_live"] = 3600 * 24; // 24 hours
+        else {
+            const auto expiration = std::chrono::system_clock::now() + std::chrono::hours(24);
+            uint32_t exp = std::chrono::duration_cast<std::chrono::seconds>(expiration.time_since_epoch()).count();
+            notification["expiration"] = exp;
+        }
 
         Json::Value notifications(Json::arrayValue);
         notifications[0] = notification;