HTTP: Make redirect response parsing more generic

To enable its use in the http2 protocol handler.
This factors out the error-reporting code for HTTP 1, which in
any case has to be done differently for HTTP 2, saving duplication
and simplifying the redirect handling code.

Task-number: QTBUG-100651
Pick-to: 6.3 6.2 5.15
Change-Id: I4b470646a9ad5ee702c9b1921d115e137d3d5b8b
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Øystein Heskestad <oystein.heskestad@qt.io>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/network/access/qhttpnetworkconnection.cpp

@@ -525,10 +525,23 @@ bool QHttpNetworkConnectionPrivate::handleAuthenticateChallenge(QAbstractSocket
     return false;
 }
 
-QUrl QHttpNetworkConnectionPrivate::parseRedirectResponse(QAbstractSocket *socket, QHttpNetworkReply *reply)
+// Used by the HTTP1 code-path
+QUrl QHttpNetworkConnectionPrivate::parseRedirectResponse(QAbstractSocket *socket,
+                                                          QHttpNetworkReply *reply)
+{
+    ParseRedirectResult result = parseRedirectResponse(reply);
+    if (result.errorCode != QNetworkReply::NoError) {
+        emitReplyError(socket, reply, result.errorCode);
+        return {};
+    }
+    return std::move(result.redirectUrl);
+}
+
+QHttpNetworkConnectionPrivate::ParseRedirectResult
+QHttpNetworkConnectionPrivate::parseRedirectResponse(QHttpNetworkReply *reply)
 {
     if (!reply->request().isFollowRedirects())
-        return QUrl();
+        return {{}, QNetworkReply::NoError};
 
     QUrl redirectUrl;
     const QList<QPair<QByteArray, QByteArray> > fields = reply->header();
@@ -539,17 +552,13 @@ QUrl QHttpNetworkConnectionPrivate::parseRedirectResponse(QAbstractSocket *socke
         }
     }
 
-    // If the location url is invalid/empty, we emit ProtocolUnknownError
-    if (!redirectUrl.isValid()) {
-        emitReplyError(socket, reply, QNetworkReply::ProtocolUnknownError);
-        return QUrl();
-    }
+    // If the location url is invalid/empty, we return ProtocolUnknownError
+    if (!redirectUrl.isValid())
+        return {{}, QNetworkReply::ProtocolUnknownError};
 
     // Check if we have exceeded max redirects allowed
-    if (reply->request().redirectCount() <= 0) {
-        emitReplyError(socket, reply, QNetworkReply::TooManyRedirectsError);
-        return QUrl();
-    }
+    if (reply->request().redirectCount() <= 0)
+        return {{}, QNetworkReply::TooManyRedirectsError};
 
     // Resolve the URL if it's relative
     if (redirectUrl.isRelative())
@@ -570,8 +579,7 @@ QUrl QHttpNetworkConnectionPrivate::parseRedirectResponse(QAbstractSocket *socke
             if (priorUrl.host() != redirectUrl.host()
                 || priorUrl.scheme() != redirectUrl.scheme()
                 || priorUrl.port() != redirectUrl.port()) {
-                emitReplyError(socket, reply, QNetworkReply::InsecureRedirectError);
-                return QUrl();
+                return {{}, QNetworkReply::InsecureRedirectError};
             }
             break;
         case QNetworkRequest::UserVerifiedRedirectPolicy:
@@ -580,10 +588,9 @@ QUrl QHttpNetworkConnectionPrivate::parseRedirectResponse(QAbstractSocket *socke
             Q_ASSERT(!"Unexpected redirect policy");
         }
     } else {
-        emitReplyError(socket, reply, QNetworkReply::ProtocolUnknownError);
-        return QUrl();
+        return {{}, QNetworkReply::ProtocolUnknownError};
     }
-    return redirectUrl;
+    return {std::move(redirectUrl), QNetworkReply::NoError};
 }
 
 void QHttpNetworkConnectionPrivate::createAuthorization(QAbstractSocket *socket, QHttpNetworkRequest &request)

src/network/access/qhttpnetworkconnection_p.h

@@ -260,6 +260,12 @@ public:
 
     void emitReplyError(QAbstractSocket *socket, QHttpNetworkReply *reply, QNetworkReply::NetworkError errorCode);
     bool handleAuthenticateChallenge(QAbstractSocket *socket, QHttpNetworkReply *reply, bool isProxy, bool &resend);
+    struct ParseRedirectResult {
+        QUrl redirectUrl;
+        QNetworkReply::NetworkError errorCode;
+    };
+    ParseRedirectResult parseRedirectResponse(QHttpNetworkReply *reply);
+    // Used by the HTTP1 code-path
     QUrl parseRedirectResponse(QAbstractSocket *socket, QHttpNetworkReply *reply);
 
 #ifndef QT_NO_NETWORKPROXY