QNAM: Reintroduce h2c with an attribute

[ChangeLog][QtNetwork][QNetworkRequest] Added
QNetworkRequest::Http2CleartextAllowedAttribute which controls whether
HTTP/2 cleartext (h2c) is allowed or not. The default is false. This
replaces the QT_NETWORK_H2C_ALLOWED environment variable.

Task-number: QTBUG-98642
Change-Id: I43ae1cc671788f6d2559cd316f6667b412c8e75e
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

5 files changed, 26 insertions, 5 deletions

diff --git a/src/network/access/qhttpnetworkrequest.cpp b/src/network/access/qhttpnetworkrequest.cpp
index f419ee2673..cfcface0d2 100644
--- a/src/network/access/qhttpnetworkrequest.cpp
+++ b/src/network/access/qhttpnetworkrequest.cpp
@@ -61,6 +61,7 @@ QHttpNetworkRequestPrivate::QHttpNetworkRequestPrivate(const QHttpNetworkRequest
       pipeliningAllowed(other.pipeliningAllowed),
       http2Allowed(other.http2Allowed),
       http2Direct(other.http2Direct),
+      h2cAllowed(other.h2cAllowed),
       withCredentials(other.withCredentials),
       ssl(other.ssl),
       preConnect(other.preConnect),
@@ -85,6 +86,7 @@ bool QHttpNetworkRequestPrivate::operator==(const QHttpNetworkRequestPrivate &ot
         && (pipeliningAllowed == other.pipeliningAllowed)
         && (http2Allowed == other.http2Allowed)
         && (http2Direct == other.http2Direct)
+        && (h2cAllowed == other.h2cAllowed)
         // we do not clear the customVerb in setOperation
         && (operation != QHttpNetworkRequest::Custom || (customVerb == other.customVerb))
         && (withCredentials == other.withCredentials)
@@ -367,12 +369,12 @@ void QHttpNetworkRequest::setHTTP2Direct(bool b)
 
 bool QHttpNetworkRequest::isH2cAllowed() const
 {
-    return qEnvironmentVariableIsSet("QT_NETWORK_H2C_ALLOWED");
+    return d->h2cAllowed;
 }
 
 void QHttpNetworkRequest::setH2cAllowed(bool b)
 {
-    Q_UNUSED(b);
+    d->h2cAllowed = b;
 }
 
 bool QHttpNetworkRequest::withCredentials() const
diff --git a/src/network/access/qhttpnetworkrequest_p.h b/src/network/access/qhttpnetworkrequest_p.h
index f4c1d7fb8c..bf6db875af 100644
--- a/src/network/access/qhttpnetworkrequest_p.h
+++ b/src/network/access/qhttpnetworkrequest_p.h
@@ -182,6 +182,7 @@ public:
     bool pipeliningAllowed;
     bool http2Allowed;
     bool http2Direct;
+    bool h2cAllowed = false;
     bool withCredentials;
     bool ssl;
     bool preConnect;
diff --git a/src/network/access/qnetworkreplyhttpimpl.cpp b/src/network/access/qnetworkreplyhttpimpl.cpp
index 502692084a..4e06a0dc08 100644
--- a/src/network/access/qnetworkreplyhttpimpl.cpp
+++ b/src/network/access/qnetworkreplyhttpimpl.cpp
@@ -790,6 +790,12 @@ void QNetworkReplyHttpImplPrivate::postRequest(const QNetworkRequest &newHttpReq
         allowed.isValid() && allowed.canConvert<bool>()) {
         httpRequest.setHTTP2Allowed(allowed.value<bool>());
     }
+    auto h2cAttribute = request.attribute(QNetworkRequest::Http2CleartextAllowedAttribute);
+    // ### Qt7: Stop checking the environment variable
+    if (h2cAttribute.toBool()
+        || (!h2cAttribute.isValid() && qEnvironmentVariableIsSet("QT_NETWORK_H2C_ALLOWED"))) {
+        httpRequest.setH2cAllowed(true);
+    }
 
     if (request.attribute(QNetworkRequest::Http2DirectAttribute).toBool()) {
         // Intentionally mutually exclusive - cannot be both direct and 'allowed'
diff --git a/src/network/access/qnetworkrequest.cpp b/src/network/access/qnetworkrequest.cpp
index 3e9c12ae9e..64d35aa278 100644
--- a/src/network/access/qnetworkrequest.cpp
+++ b/src/network/access/qnetworkrequest.cpp
@@ -272,7 +272,8 @@ QT_BEGIN_NAMESPACE
         Requests only, type: QMetaType::Bool (default: true)
         Indicates whether the QNetworkAccessManager code is
         allowed to use HTTP/2 with this request. This applies
-        to SSL requests or 'cleartext' HTTP/2.
+        to SSL requests or 'cleartext' HTTP/2 if Http2CleartextAllowedAttribute
+        is set.
 
     \value Http2WasUsedAttribute
         Replies only, type: QMetaType::Bool (default: false)
@@ -304,8 +305,9 @@ QT_BEGIN_NAMESPACE
         If set, this attribute will force QNetworkAccessManager to use
         HTTP/2 protocol without initial HTTP/2 protocol negotiation.
         Use of this attribute implies prior knowledge that a particular
-        server supports HTTP/2. The attribute works with SSL or 'cleartext'
-        HTTP/2. If a server turns out to not support HTTP/2, when HTTP/2 direct
+        server supports HTTP/2. The attribute works with SSL or with 'cleartext'
+        HTTP/2 if Http2CleartextAllowedAttribute is set.
+        If a server turns out to not support HTTP/2, when HTTP/2 direct
         was specified, QNetworkAccessManager gives up, without attempting to
         fall back to HTTP/1.1. If both Http2AllowedAttribute and
         Http2DirectAttribute are set, Http2DirectAttribute takes priority.
@@ -325,6 +327,15 @@ QT_BEGIN_NAMESPACE
         be closed after the last pending request had been processed.
         (This value was introduced in 6.3.)
 
+    \value Http2CleartextAllowedAttribute
+        Requests only, type: QMetaType::Bool (default: false)
+        If set, this attribute will tell QNetworkAccessManager to attempt
+        an upgrade to HTTP/2 over cleartext (also known as h2c).
+        Until Qt 7 the default value for this attribute can be overridden
+        to true by setting the QT_NETWORK_H2C_ALLOWED environment variable.
+        This attribute is ignored if the Http2AllowedAttribute is not set.
+        (This value was introduced in 6.3.)
+
     \value User
         Special type. Additional information can be passed in
         QVariants with types ranging from User to UserMax. The default
diff --git a/src/network/access/qnetworkrequest.h b/src/network/access/qnetworkrequest.h
index bdcb1c80a9..5d5ae292c8 100644
--- a/src/network/access/qnetworkrequest.h
+++ b/src/network/access/qnetworkrequest.h
@@ -98,6 +98,7 @@ public:
         ResourceTypeAttribute, // internal
         AutoDeleteReplyOnFinishAttribute,
         ConnectionCacheExpiryTimeoutSecondsAttribute,
+        Http2CleartextAllowedAttribute,
 
         User = 1000,
         UserMax = 32767