Fix Botan 3 build (#9388)

* SymmetricCipher: Fix Botan 3 build

Botan commit 819cf8fe6278a19b8266f449228f02fc28a4f784 changed
Botan::Cipher_Dir to be a scoped enumeration, so the users
must be adapted.

This change causes no issues with Botan 2 because normal
enumeration values can also be referred to the same way
scoped enumeration values are accessed.

* Auto detect Botan3

* AsyncTask: Do not use `std::result_of`

`std::result_of` was deprecated in C++17 and then it was
subsequently removed in C++20. One could use `std::invoke_result_t`,
but let Qt figure out the return type instead.

* Collapse Botan2 and Botan3 find package into one

* Update COPYING

---------

Co-authored-by: Jonathan White <support@dmapps.us>

src/config-keepassx.h.cmake

@@ -14,7 +14,6 @@
 
 #cmakedefine WITH_XC_AUTOTYPE
 #cmakedefine WITH_XC_NETWORKING
-#cmakedefine KPXC_DEV_BOTAN3
 #cmakedefine WITH_XC_BROWSER
 #cmakedefine WITH_XC_YUBIKEY
 #cmakedefine WITH_XC_SSHAGENT
@@ -23,6 +22,7 @@
 #cmakedefine WITH_XC_FDOSECRETS
 #cmakedefine WITH_XC_DOCS
 #cmakedefine WITH_XC_X11
+#cmakedefine WITH_XC_BOTAN3
 
 #cmakedefine KEEPASSXC_BUILD_TYPE "@KEEPASSXC_BUILD_TYPE@"
 #cmakedefine KEEPASSXC_BUILD_TYPE_RELEASE

src/core/AsyncTask.h

@@ -33,12 +33,10 @@ namespace AsyncTask
      * @param future future to wait for
      * @return async task result
      */
-    template <typename FunctionObject>
-    typename std::result_of<FunctionObject()>::type
-    waitForFuture(QFuture<typename std::result_of<FunctionObject()>::type> future)
+    template <typename T> T waitForFuture(QFuture<T> future)
     {
         QEventLoop loop;
-        QFutureWatcher<typename std::result_of<FunctionObject()>::type> watcher;
+        QFutureWatcher<T> watcher;
         QObject::connect(&watcher, SIGNAL(finished()), &loop, SLOT(quit()));
         watcher.setFuture(future);
         loop.exec();
@@ -51,10 +49,9 @@ namespace AsyncTask
      * @param task std::function object to run
      * @return async task result
      */
-    template <typename FunctionObject>
-    typename std::result_of<FunctionObject()>::type runAndWaitForFuture(FunctionObject task)
+    template <typename FunctionObject> decltype(auto) runAndWaitForFuture(FunctionObject task)
     {
-        return waitForFuture<FunctionObject>(QtConcurrent::run(task));
+        return waitForFuture(QtConcurrent::run(task));
     }
 
     /**
@@ -69,9 +66,8 @@ namespace AsyncTask
     template <typename FunctionObject, typename FunctionObject2>
     void runThenCallback(FunctionObject task, QObject* context, FunctionObject2 callback)
     {
-        typedef QFutureWatcher<typename std::result_of<FunctionObject()>::type> FutureWatcher;
         auto future = QtConcurrent::run(task);
-        auto watcher = new FutureWatcher(context);
+        auto watcher = new QFutureWatcher<decltype(future.result())>(context);
         QObject::connect(watcher, &QFutureWatcherBase::finished, context, [=]() {
             watcher->deleteLater();
             callback(future.result());

src/crypto/Crypto.cpp

@@ -239,7 +239,7 @@ namespace Crypto
 {
     bool init()
     {
-#ifdef KPXC_DEV_BOTAN3
+#ifdef WITH_XC_BOTAN3
         unsigned int version_major = 3, min_version_minor = 0;
         QString versionString = "3.x";
 #else

src/crypto/SymmetricCipher.cpp

@@ -33,7 +33,8 @@ bool SymmetricCipher::init(Mode mode, Direction direction, const QByteArray& key
 
     try {
         auto botanMode = modeToString(mode);
-        auto botanDirection = (direction == SymmetricCipher::Encrypt ? Botan::ENCRYPTION : Botan::DECRYPTION);
+        auto botanDirection =
+            (direction == SymmetricCipher::Encrypt ? Botan::Cipher_Dir::ENCRYPTION : Botan::Cipher_Dir::DECRYPTION);
 
         auto cipher = Botan::Cipher_Mode::create_or_throw(botanMode.toStdString(), botanDirection);
         m_cipher.reset(cipher.release());

src/fdosecrets/objects/SessionCipher.cpp

@@ -25,7 +25,7 @@
 #include <QDebug>
 #include <botan/dh.h>
 
-#ifdef KPXC_DEV_BOTAN3
+#ifdef WITH_XC_BOTAN3
 #include <botan/pubkey.h>
 #else
 #include <botan/pk_ops.h>
@@ -57,7 +57,7 @@ namespace FdoSecrets
 
         try {
             Botan::secure_vector<uint8_t> salt(32, '\0');
-#ifdef KPXC_DEV_BOTAN3
+#ifdef WITH_XC_BOTAN3
             Botan::PK_Key_Agreement dhka(*m_privateKey, *randomGen()->getRng(), "HKDF(SHA-256)", "");
             auto aesKey = dhka.derive_key(16,
                                           reinterpret_cast<const uint8_t*>(clientPublicKey.constData()),