Add QWebEngineUrlScheme class

Public API for the new url/url_util_qt extension to Chromium, which allows to
integrate custom schemes into Chromium's url parsing library and security model.
Previously custom schemes would be treated as 'unknown' schemes and rely on
fallback behavior in Chromium.

[ChangeLog][Custom Schemes] Added the QWebEngineUrlScheme class for configuring
how custom schemes are parsed and which security restrictions should apply.

Task-number: QTBUG-62536
Change-Id: I7d8b9da3ad742f568b82ccc6a2456ad35e84069b
Reviewed-by: Michal Klocek <michal.klocek@qt.io>

2 files changed, 21 insertions, 4 deletions

diff --git a/src/webengine/api/qquickwebengineprofile.cpp b/src/webengine/api/qquickwebengineprofile.cpp
index d11214716..48e5175ca 100644
--- a/src/webengine/api/qquickwebengineprofile.cpp
+++ b/src/webengine/api/qquickwebengineprofile.cpp
@@ -836,22 +836,26 @@ static bool checkInternalScheme(const QByteArray &scheme)
 
 /*!
     Registers a handler \a handler for custom URL scheme \a scheme in the profile.
+
+    It is recommended to first register the scheme with \l
+    QWebEngineUrlScheme::addScheme at application startup.
 */
 void QQuickWebEngineProfile::installUrlSchemeHandler(const QByteArray &scheme, QWebEngineUrlSchemeHandler *handler)
 {
     Q_D(QQuickWebEngineProfile);
     Q_ASSERT(handler);
-    if (checkInternalScheme(scheme)) {
+    QByteArray canonicalScheme = scheme.toLower();
+    if (checkInternalScheme(canonicalScheme)) {
         qWarning("Cannot install a URL scheme handler overriding internal scheme: %s", scheme.constData());
         return;
     }
 
-    if (d->profileAdapter()->customUrlSchemeHandlers().contains(scheme)) {
-        if (d->profileAdapter()->customUrlSchemeHandlers().value(scheme) != handler)
+    if (d->profileAdapter()->customUrlSchemeHandlers().contains(canonicalScheme)) {
+        if (d->profileAdapter()->customUrlSchemeHandlers().value(canonicalScheme) != handler)
             qWarning("URL scheme handler already installed for the scheme: %s", scheme.constData());
         return;
     }
-    d->profileAdapter()->addCustomUrlSchemeHandler(scheme, handler);
+    d->profileAdapter()->addCustomUrlSchemeHandler(canonicalScheme, handler);
     connect(handler, SIGNAL(_q_destroyedUrlSchemeHandler(QWebEngineUrlSchemeHandler*)), this, SLOT(destroyedUrlSchemeHandler(QWebEngineUrlSchemeHandler*)));
 }
 
diff --git a/src/webengine/doc/src/qtwebengine-features.qdoc b/src/webengine/doc/src/qtwebengine-features.qdoc
index d900e551b..41d0581e5 100644
--- a/src/webengine/doc/src/qtwebengine-features.qdoc
+++ b/src/webengine/doc/src/qtwebengine-features.qdoc
@@ -111,6 +111,19 @@
 
     For more information, see \l {Qt WebEngine Debugging and Profiling}.
 
+    \section1 Custom Schemes
+
+    Qt WebEngine makes it possible for the application to define its own custom
+    URL schemes with specialized security policies and transport mechanisms.
+
+    Custom schemes can be used to implement alternative network protocols with
+    all the usual web security policies, privileged internal schemes for
+    displaying user interface compoments or debugging information, sandboxed
+    schemes with extra restrictions, and so on.
+
+    For more information, see \l QWebEngineUrlScheme and \l
+    QWebEngineUrlSchemeHandler.
+
     \section1 Drag and Drop
 
     Qt WebEngine supports HTML5 drag and drop.