Fetch favicon from the root of the website and use Google as a fallback (#36)

* Replace favicon fetching using Google with fetching from the root of the website
* Follow up to 3 http redirects for the favicon
* Add download favicon from Google as fallback
* Move code responsible for fetching the favicon from Google on its own function to reduce repetitiveness.

src/gui/EditWidgetIcons.cpp

@@ -143,28 +143,54 @@ void EditWidgetIcons::setUrl(const QString &url)
 
 void EditWidgetIcons::downloadFavicon()
 {
-    if (m_networkOperation == nullptr) {
-        QUrl url(m_url);
-        QString path = "http://www.google.com/s2/favicons?domain=" + url.host();
+    QUrl url = QUrl(m_url);
+    url.setPath("/favicon.ico");
+    fetchFavicon(url);
+}
 
-        m_networkOperation = m_networkAccessMngr->get(QNetworkRequest(path));
+void EditWidgetIcons::fetchFavicon(QUrl url)
+{
+    if (m_networkOperation == nullptr) {
+        m_networkOperation = m_networkAccessMngr->get(QNetworkRequest(url));
         m_ui->faviconButton->setDisabled(true);
     }
 }
 
-void EditWidgetIcons::abortFaviconDownload()
+void EditWidgetIcons::fetchFaviconFromGoogle(QString domain)
+{
+     if (m_fallbackToGoogle) {
+        abortFaviconDownload();
+        m_fallbackToGoogle = false;
+        fetchFavicon(QUrl("http://www.google.com/s2/favicons?domain=" + domain));
+    }
+    else {
+        abortFaviconDownload();
+        MessageBox::warning(this, tr("Error"), tr("Unable to fetch favicon."));
+    }
+}
+
+void EditWidgetIcons::abortFaviconDownload(bool clearRedirect)
 {
     if (m_networkOperation != nullptr) {
         m_networkOperation->abort();
         m_networkOperation->deleteLater();
         m_networkOperation = nullptr;
     }
+    
+    if (clearRedirect) {
+        if (!m_redirectUrl.isEmpty()) {
+            m_redirectUrl.clear();
+        }
+        m_redirectCount = 0;
+    }
+    
+    m_fallbackToGoogle = true;
     m_ui->faviconButton->setDisabled(false);
 }
 
 void EditWidgetIcons::onRequestFinished(QNetworkReply *reply)
 {
-    if (!reply->error()) {
+    if (!reply->error()) {    
         QImage image;
         image.loadFromData(reply->readAll());
 
@@ -177,10 +203,26 @@ void EditWidgetIcons::onRequestFinished(QNetworkReply *reply)
             QModelIndex index = m_customIconModel->indexFromUuid(uuid);
             m_ui->customIconsView->setCurrentIndex(index);
             m_ui->customIconsRadio->setChecked(true);
+            
+            abortFaviconDownload();
+        }
+        else {
+            // Check if server has sent a redirect
+            QUrl possibleRedirectUrl = reply->attribute(QNetworkRequest::RedirectionTargetAttribute).toUrl();
+            if (!possibleRedirectUrl.isEmpty() && possibleRedirectUrl != m_redirectUrl && m_redirectCount < 3) {
+                abortFaviconDownload(false);
+                m_redirectUrl = possibleRedirectUrl;
+                ++m_redirectCount;
+                fetchFavicon(m_redirectUrl);
+            }
+            else { // Webpage is trying to redirect back to itself or the maximum number of redirects has been reached, fallback to Google
+                fetchFaviconFromGoogle(reply->url().host());
+            }
         }
     }
-
-    abortFaviconDownload();
+    else { // Request Error e.g. 404, fallback to Google
+        fetchFaviconFromGoogle(reply->url().host());
+    }
 }
 
 void EditWidgetIcons::addCustomIcon()

src/gui/EditWidgetIcons.h

@@ -60,7 +60,9 @@ public Q_SLOTS:
 
 private Q_SLOTS:
     void downloadFavicon();
-    void abortFaviconDownload();
+    void fetchFavicon(QUrl url);
+    void fetchFaviconFromGoogle(QString domain);
+    void abortFaviconDownload(bool clearRedirect = true);
     void onRequestFinished(QNetworkReply *reply);
     void addCustomIcon();
     void removeCustomIcon();
@@ -74,6 +76,9 @@ private:
     Database* m_database;
     Uuid m_currentUuid;
     QString m_url;
+    QUrl m_redirectUrl;
+    bool m_fallbackToGoogle = true;
+    unsigned short m_redirectCount = 0;
     DefaultIconModel* const m_defaultIconModel;
     CustomIconModel* const m_customIconModel;
     QNetworkAccessManager* const m_networkAccessMngr;