Add Subsonic option to turn off HTTP2

Fixes #718

src/subsonic/subsonicbaserequest.cpp

@@ -100,6 +100,10 @@ QNetworkReply *SubsonicBaseRequest::CreateGetRequest(const QString &ressource_na
   req.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
 #endif
 
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
+  req.setAttribute(QNetworkRequest::Http2AllowedAttribute, http2());
+#endif
+
   QNetworkReply *reply = network_->get(req);
   QObject::connect(reply, &QNetworkReply::sslErrors, this, &SubsonicBaseRequest::HandleSSLErrors);
 

src/subsonic/subsonicbaserequest.h

@@ -61,13 +61,14 @@ class SubsonicBaseRequest : public QObject {
   virtual void Error(const QString &error, const QVariant &debug = QVariant()) = 0;
   QString ErrorsToHTML(const QStringList &errors);
 
-  QString client_name() { return service_->client_name(); }
-  QString api_version() { return service_->api_version(); }
-  QUrl server_url() { return service_->server_url(); }
-  QString username() { return service_->username(); }
-  QString password() { return service_->password(); }
-  bool verify_certificate() { return service_->verify_certificate(); }
-  bool download_album_covers() { return service_->download_album_covers(); }
+  QString client_name() const { return service_->client_name(); }
+  QString api_version() const { return service_->api_version(); }
+  QUrl server_url() const { return service_->server_url(); }
+  QString username() const { return service_->username(); }
+  QString password() const { return service_->password(); }
+  bool http2() const { return service_->http2(); }
+  bool verify_certificate() const { return service_->verify_certificate(); }
+  bool download_album_covers() const { return service_->download_album_covers(); }
 
  private slots:
   void HandleSSLErrors(QList<QSslError> ssl_errors);

src/subsonic/subsonicrequest.cpp

@@ -735,6 +735,10 @@ void SubsonicRequest::FlushAlbumCoverRequests() {
     req.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
 #endif
 
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
+    req.setAttribute(QNetworkRequest::Http2AllowedAttribute, http2());
+#endif
+
     if (!verify_certificate()) {
       QSslConfiguration sslconfig = QSslConfiguration::defaultConfiguration();
       sslconfig.setPeerVerifyMode(QSslSocket::VerifyNone);

src/subsonic/subsonicservice.cpp

@@ -73,6 +73,7 @@ SubsonicService::SubsonicService(Application *app, QObject *parent)
       collection_backend_(nullptr),
       collection_model_(nullptr),
       collection_sort_model_(new QSortFilterProxyModel(this)),
+      http2_(true),
       verify_certificate_(false),
       download_album_covers_(true),
       ping_redirects_(0)
@@ -138,6 +139,7 @@ void SubsonicService::ReloadSettings() {
   if (password.isEmpty()) password_.clear();
   else password_ = QString::fromUtf8(QByteArray::fromBase64(password));
 
+  http2_ = s.value("http2", true).toBool();
   verify_certificate_ = s.value("verifycertificate", false).toBool();
   download_album_covers_ = s.value("downloadalbumcovers", true).toBool();
 
@@ -196,6 +198,10 @@ void SubsonicService::SendPingWithCredentials(QUrl url, const QString &username,
 
   req.setHeader(QNetworkRequest::ContentTypeHeader, "application/x-www-form-urlencoded");
 
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
+  req.setAttribute(QNetworkRequest::Http2AllowedAttribute, http2_);
+#endif
+
   errors_.clear();
   QNetworkReply *reply = network_->get(req);
   replies_ << reply;

src/subsonic/subsonicservice.h

@@ -62,19 +62,20 @@ class SubsonicService : public InternetService {
   void ReloadSettings() override;
   void Exit() override;
 
-  Application *app() { return app_; }
+  Application *app() const { return app_; }
 
-  QString client_name() { return kClientName; }
-  QString api_version() { return kApiVersion; }
-  QUrl server_url() { return server_url_; }
-  QString username() { return username_; }
-  QString password() { return password_; }
-  bool verify_certificate() { return verify_certificate_; }
-  bool download_album_covers() { return download_album_covers_; }
+  QString client_name() const { return kClientName; }
+  QString api_version() const { return kApiVersion; }
+  QUrl server_url() const { return server_url_; }
+  QString username() const { return username_; }
+  QString password() const { return password_; }
+  bool http2() const { return http2_; }
+  bool verify_certificate() const { return verify_certificate_; }
+  bool download_album_covers() const { return download_album_covers_; }
 
-  CollectionBackend *collection_backend() { return collection_backend_; }
-  CollectionModel *collection_model() { return collection_model_; }
-  QSortFilterProxyModel *collection_sort_model() { return collection_sort_model_; }
+  CollectionBackend *collection_backend() const { return collection_backend_; }
+  CollectionModel *collection_model() const { return collection_model_; }
+  QSortFilterProxyModel *collection_sort_model() const { return collection_sort_model_; }
 
   CollectionBackend *songs_collection_backend() override { return collection_backend_; }
   CollectionModel *songs_collection_model() override { return collection_model_; }
@@ -124,6 +125,7 @@ class SubsonicService : public InternetService {
   QUrl server_url_;
   QString username_;
   QString password_;
+  bool http2_;
   bool verify_certificate_;
   bool download_album_covers_;