QSslSocket: OpenSSL 1.1 backend

This patch-set implements a new QSslSocket backend based on OpenSSL 1.1.

1. General.

The code in this patch was organized to achieve these (somewhat contradicting)
objectives:
- keep the new code free of #if-ery, as far as possible;
- make it easy to clean away dead code when we're eventually able to retire
  out-dated OpenSSL versions;
- reduce the amount of code duplication.

If changes in some file/component were insignificant (~5 one-liners per file),
we still use pp-checks like: #if QT_CONFIG(opensslv11) ... #else ... #endif -
the logic is simple and it's still easy to clean the code if we remove the legacy
back-end. Where it saved #if-ery, we also introduced 'forward-compatible'
macros implementing equivalents of 1.1 functions using older OpenSSL.

In case some class contains a lot of version-specific ifdefs (particularly where
nested #if-ery was complex) we choose to split code into: "pre11" h/cpp files,
"shared" h/cpp files (they preserve their original names, e.g qsslsocket_openssl.cpp)
and "11" h/cpp files. If in future we remove the legacy back-end, "pre11" should be
removed; "shared" and "11" parts - merged.

2. Configuration.

We introduced a new feature 'opensslv11' which complements the pre-existing
'openssl' and 'openssl-linked' features. The 'opensslv11' feature is enabled
by a simple test which either compiles successfully or ends in a compilation
error, depending on a value of the OPENSSL_VERSION_NUMBER constant. If the
feature was enabled, we also append an additional compilation flag
-DOPENSSL_API_COMPAT=0x10100000L to make sure our new code does not contain
deprecated structures, function calls, macro-invocations from OpenSSL < 1.1.

Change-Id: I2064efbe9685def5d2bb2233a66f7581954fb74a
Reviewed-by: André Klitzing <aklitzing@gmail.com>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

2 files changed, 50 insertions, 0 deletions

diff --git a/config.tests/unix/openssl11/openssl.cpp b/config.tests/unix/openssl11/openssl.cpp
new file mode 100644
index 0000000000..c20cc59deb
--- /dev/null
+++ b/config.tests/unix/openssl11/openssl.cpp
@@ -0,0 +1,48 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the config.tests of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <openssl/opensslv.h>
+
+#if !defined(OPENSSL_VERSION_NUMBER) || OPENSSL_VERSION_NUMBER-0 < 0x10100000L
+#  error "OpenSSL >= 1.1 is required"
+#endif
+
+int main()
+{
+}
diff --git a/config.tests/unix/openssl11/openssl.pro b/config.tests/unix/openssl11/openssl.pro
new file mode 100644
index 0000000000..a023aee4aa
--- /dev/null
+++ b/config.tests/unix/openssl11/openssl.pro
@@ -0,0 +1,2 @@
+SOURCES = openssl.cpp
+CONFIG -= x11 qt