proxy client: fix leak in sendListen

src/dht_proxy_client.cpp

@@ -1121,11 +1121,13 @@ DhtProxyClient::sendListen(const restinio::http_request_header_t& header,
             std::lock_guard<std::mutex> l(requestLock_);
             requests_[reqid] = request;
         }
-        request->add_on_status_callback([request, seconds = this->listenKeepIdle()] (unsigned status_code) {
+        request->add_on_status_callback([r=std::weak_ptr(request), seconds = this->listenKeepIdle()] (unsigned status_code) {
             if(status_code == 200) {
                 // increase TCP_KEEPIDLE to save power
+                if (auto request = r.lock()) {
                     request->get_connection()->set_keepalive(seconds);
                 }
+            }
         });
         request->send();
     }