Major plugin refactor and cleanup.

Switched to POCO library for unified platform/library interface.
Deprecated the external module API. It was creating more problems than solving.
Removed most built-in libraries in favor of system libraries for easier maintenance.
Cleaned and secured code with help from static analyzers.

vendor/POCO/Foundation/include/Poco/DigestEngine.h

@@ -0,0 +1,111 @@
+//
+// DigestEngine.h
+//
+// Library: Foundation
+// Package: Crypt
+// Module:  DigestEngine
+//
+// Definition of class DigestEngine.
+//
+// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#ifndef Foundation_DigestEngine_INCLUDED
+#define Foundation_DigestEngine_INCLUDED
+
+
+#include "Poco/Foundation.h"
+#include <vector>
+
+
+namespace Poco {
+
+
+class Foundation_API DigestEngine
+	/// This class is an abstract base class
+	/// for all classes implementing a message
+	/// digest algorithm, like MD5Engine
+	/// and SHA1Engine.
+	/// Call update() repeatedly with data to
+	/// compute the digest from. When done,
+	/// call digest() to obtain the message
+	/// digest.
+{
+public:
+	using Digest = std::vector<unsigned char>;
+
+	DigestEngine();
+	virtual ~DigestEngine();
+
+	void update(const void* data, std::size_t length);
+	void update(char data);
+	void update(const std::string& data);
+		/// Updates the digest with the given data.
+
+	virtual std::size_t digestLength() const = 0;
+		/// Returns the length of the digest in bytes.
+
+	virtual void reset() = 0;
+		/// Resets the engine so that a new
+		/// digest can be computed.
+
+	virtual const Digest& digest() = 0;
+		/// Finishes the computation of the digest and
+		/// returns the message digest. Resets the engine
+		/// and can thus only be called once for every digest.
+		/// The returned reference is valid until the next
+		/// time digest() is called, or the engine object is destroyed.
+
+	static std::string digestToHex(const Digest& bytes);
+		/// Converts a message digest into a string of hexadecimal numbers.
+
+	static Digest digestFromHex(const std::string& digest);
+		/// Converts a string created by digestToHex back to its Digest presentation
+
+	static bool constantTimeEquals(const Digest& d1, const Digest& d2);
+		/// Compares two Digest values using a constant-time comparison
+		/// algorithm. This can be used to prevent timing attacks
+		/// (as discussed in <https://codahale.com/a-lesson-in-timing-attacks/>).
+
+protected:
+	virtual void updateImpl(const void* data, std::size_t length) = 0;
+		/// Updates the digest with the given data. Must be implemented
+		/// by subclasses.
+
+private:
+	DigestEngine(const DigestEngine&);
+	DigestEngine& operator = (const DigestEngine&);
+};
+
+
+//
+// inlines
+//
+
+
+inline void DigestEngine::update(const void* data, std::size_t length)
+{
+	updateImpl(data, length);
+}
+
+
+inline void DigestEngine::update(char data)
+{
+	updateImpl(&data, 1);
+}
+
+
+inline void DigestEngine::update(const std::string& data)
+{
+	updateImpl(data.data(), data.size());
+}
+
+
+} // namespace Poco
+
+
+#endif // Foundation_DigestEngine_INCLUDED