Retry serverinfo query for adding a PC if the request fails with ServiceUnavailableError. Fixes #88

app/backend/computermanager.cpp

@@ -400,6 +400,8 @@ private:
            }
         } catch (const GfeHttpResponseException& e) {
             emit pairingCompleted(m_Computer, e.toQString());
+        } catch (const QtNetworkReplyException& e) {
+            emit pairingCompleted(m_Computer, e.toQString());
         }
     }
 
@@ -452,6 +454,12 @@ private:
             else {
                 emit quitAppFailed(e.toQString());
             }
+        } catch (const QtNetworkReplyException& e) {
+            {
+                QWriteLocker lock(&m_Computer->lock);
+                m_Computer->pendingQuit = false;
+            }
+            emit quitAppFailed(e.toQString());
         }
     }
 
@@ -535,7 +543,24 @@ private:
 
         QString serverInfo;
         try {
-            serverInfo = http.getServerInfo(NvHTTP::NvLogLevel::VERBOSE);
+            // There's a race condition between GameStream servers reporting presence over
+            // mDNS and the HTTPS server being ready to respond to our queries. To work
+            // around this issue, we will issue the request again after a few seconds if
+            // we see a ServiceUnavailableError error.
+            try {
+                serverInfo = http.getServerInfo(NvHTTP::NvLogLevel::VERBOSE);
+            } catch (const QtNetworkReplyException& e) {
+                if (e.getError() == QNetworkReply::ServiceUnavailableError) {
+                    qWarning() << "Retrying request in 5 seconds after ServiceUnavailableError";
+                    QThread::sleep(5);
+                    serverInfo = http.getServerInfo(NvHTTP::NvLogLevel::VERBOSE);
+                    qInfo() << "Retry successful";
+                }
+                else {
+                    // Rethrow other errors
+                    throw e;
+                }
+            }
         } catch (...) {
             if (!m_Mdns) {
                 emit computerAddCompleted(false);

app/backend/nvhttp.cpp

@@ -419,7 +419,7 @@ NvHTTP::openConnection(QUrl baseUrl,
         if (logLevel >= NvLogLevel::ERROR) {
             qWarning() << command << " request failed with error " << reply->error();
         }
-        GfeHttpResponseException exception(reply->error(), reply->errorString());
+        QtNetworkReplyException exception(reply->error(), reply->errorString());
         delete reply;
         throw exception;
     }

app/backend/nvhttp.h

@@ -5,7 +5,8 @@
 #include <Limelight.h>
 
 #include <QUrl>
-#include <QtNetwork/QNetworkAccessManager>
+#include <QNetworkAccessManager>
+#include <QNetworkReply>
 
 class NvApp
 {
@@ -52,7 +53,7 @@ public:
 
     }
 
-    const char* what() const throw()
+    const char* what() const
     {
         return m_StatusMessage.toLatin1();
     }
@@ -77,6 +78,41 @@ private:
     QString m_StatusMessage;
 };
 
+class QtNetworkReplyException : public std::exception
+{
+public:
+    QtNetworkReplyException(QNetworkReply::NetworkError error, QString errorText) :
+        m_Error(error),
+        m_ErrorText(errorText)
+    {
+
+    }
+
+    const char* what() const
+    {
+        return m_ErrorText.toLatin1();
+    }
+
+    const char* getErrorText() const
+    {
+        return m_ErrorText.toLatin1();
+    }
+
+    QNetworkReply::NetworkError getError() const
+    {
+        return m_Error;
+    }
+
+    QString toQString() const
+    {
+        return m_ErrorText + " (Error " + QString::number(m_Error) + ")";
+    }
+
+private:
+    QNetworkReply::NetworkError m_Error;
+    QString m_ErrorText;
+};
+
 class NvHTTP
 {
 public:

app/streaming/session.cpp

@@ -779,6 +779,10 @@ void Session::exec(int displayOriginX, int displayOriginY)
         emit displayLaunchError(e.toQString());
         s_ActiveSessionSemaphore.release();
         return;
+    } catch (const QtNetworkReplyException& e) {
+        emit displayLaunchError(e.toQString());
+        s_ActiveSessionSemaphore.release();
+        return;
     }
 
     SDL_assert(!SDL_WasInit(SDL_INIT_VIDEO));