Implement 'preconnect-https' and 'preconnect-http' for H2

QNetworkAccessManager::connectToHostEncrypted()/connectToHost()
creates 'fake' requests with pseudo-schemes 'preconnect-https'/
'preconnect-http'. QHttp2ProtocolHandler should handle this
requests in a special way - reporting them immediately as
finished (so that QNAM emits finished as it does in case of
HTTP/1.1) and not trying to send anything.
We also have to properly cache the connection - 'https' or
'http' scheme is too generic - it allows (unfortunately)
mixing H2/HTTP/1.1 in a single connection in case an attribute
was missing on a request, which is wrong.
h2c is more complicated, since it needs a real request
to negotiate the protocol switch to H2, with the current
QNetworkHttpConnection(Channel)'s design it's not possible
without large changes (aka regressions and new bugs introduced).

Auto-test extended.

Fixes: QTBUG-77082
Change-Id: I03467673a620c89784c2d36521020dc9d08aced7
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 5 insertions, 4 deletions

diff --git a/src/network/access/qnetworkaccessmanager.cpp b/src/network/access/qnetworkaccessmanager.cpp
index 85e2c492e4..31b1dbf2a5 100644
--- a/src/network/access/qnetworkaccessmanager.cpp
+++ b/src/network/access/qnetworkaccessmanager.cpp
@@ -1192,10 +1192,11 @@ void QNetworkAccessManager::connectToHostEncrypted(const QString &hostName, quin
     if (sslConfiguration != QSslConfiguration::defaultConfiguration())
         request.setSslConfiguration(sslConfiguration);
 
-    // There is no way to enable SPDY via a request, so we need to check
-    // the ssl configuration whether SPDY is allowed here.
-    if (sslConfiguration.allowedNextProtocols().contains(
-                QSslConfiguration::NextProtocolSpdy3_0))
+    // There is no way to enable SPDY/HTTP2 via a request, so we need to check
+    // the ssl configuration whether SPDY/HTTP2 is allowed here.
+    if (sslConfiguration.allowedNextProtocols().contains(QSslConfiguration::ALPNProtocolHTTP2))
+        request.setAttribute(QNetworkRequest::HTTP2AllowedAttribute, true);
+    else if (sslConfiguration.allowedNextProtocols().contains(QSslConfiguration::NextProtocolSpdy3_0))
         request.setAttribute(QNetworkRequest::SpdyAllowedAttribute, true);
 
     get(request);