HTTP/2 - implement the proper 'h2c' (protocol upgrade)

Without TLS (and thus ALPN/NPN negotiation) HTTP/2 requires
a protocol upgrade procedure, as described in RFC 7540, 3.2.
We start as HTTP/1.1 (and thus we create QHttpProtocolHandler first),
augmenting the headers we send with 'Upgrade: h2c'. In case
we receive HTTP/1.1 response with status code 101 ('Switching
Protocols'), we continue as HTTP/2 session, creating QHttp2ProtocolHandler
and pretending the first request we sent was HTTP/2 request
on a real HTTP/2 stream. If the first response is something different
from 101, we continue as HTTP/1.1. This change also required
auto-test update: our toy-server now has to respond to
the initial HTTP/1.1 request on a platform without ALPN/NPN.
As a bonus a subtle flakyness in 'goaway' auto-test went
away (well, it was fixed).

[ChangeLog][QtNetwork][HTTP/2] In case of clear text HTTP/2 we
now initiate a required protocol upgrade procedure instead of
'H2Direct' connection.

Task-number: QTBUG-61397
Change-Id: I573fa304fdaf661490159037dc47775d97c8ea5b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

1 files changed, 4 insertions, 1 deletions

diff --git a/tests/auto/network/access/http2/tst_http2.cpp b/tests/auto/network/access/http2/tst_http2.cpp
index d7a57f5e26..e433293a2c 100644
--- a/tests/auto/network/access/http2/tst_http2.cpp
+++ b/tests/auto/network/access/http2/tst_http2.cpp
@@ -47,10 +47,12 @@
 #include <cstdlib>
 #include <string>
 
-// At the moment our HTTP/2 imlpementation requires ALPN and this means OpenSSL.
 #if !defined(QT_NO_OPENSSL) && OPENSSL_VERSION_NUMBER >= 0x10002000L && !defined(OPENSSL_NO_TLSEXT)
+// HTTP/2 over TLS requires ALPN/NPN to negotiate the protocol version.
 const bool clearTextHTTP2 = false;
 #else
+// No ALPN/NPN support to negotiate HTTP/2, we'll use cleartext 'h2c' with
+// a protocol upgrade procedure.
 const bool clearTextHTTP2 = true;
 #endif
 
@@ -507,6 +509,7 @@ void tst_Http2::sendRequest(int streamNumber,
 
     QNetworkRequest request(url);
     request.setAttribute(QNetworkRequest::HTTP2AllowedAttribute, QVariant(true));
+    request.setHeader(QNetworkRequest::ContentTypeHeader, QVariant("text/plain"));
     request.setPriority(priority);
 
     QNetworkReply *reply = nullptr;