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/NetSSL_OpenSSL/src/Utility.cpp

@@ -0,0 +1,71 @@
+//
+// Utility.cpp
+//
+// Library: NetSSL_OpenSSL
+// Package: SSLCore
+// Module:  Utility
+//
+// Copyright (c) 2006-2009, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/Net/Utility.h"
+#include "Poco/String.h"
+#include "Poco/Util/OptionException.h"
+#include <openssl/err.h>
+
+
+namespace Poco {
+namespace Net {
+
+
+Context::VerificationMode Utility::convertVerificationMode(const std::string& vMode)
+{
+	std::string mode = Poco::toLower(vMode);
+	Context::VerificationMode verMode = Context::VERIFY_STRICT;
+
+	if (mode == "none")
+		verMode = Context::VERIFY_NONE;
+	else if (mode == "relaxed")
+		verMode = Context::VERIFY_RELAXED;
+	else if (mode == "strict")
+		verMode = Context::VERIFY_STRICT;
+	else if (mode == "once")
+		verMode = Context::VERIFY_ONCE;
+	else
+		throw Poco::InvalidArgumentException("Invalid verification mode. Should be relaxed, strict or once but got", vMode);
+
+	return verMode;
+}
+
+
+std::string Utility::convertCertificateError(long errCode)
+{
+	std::string errMsg(X509_verify_cert_error_string(errCode));
+	return errMsg;
+}
+
+
+std::string Utility::getLastError()
+{
+	unsigned long errCode = ERR_get_error();
+	if (errCode != 0)
+	{
+		char buffer[256];
+		ERR_error_string_n(errCode, buffer, sizeof(buffer));
+		return std::string(buffer);
+	}
+	else return "No error";
+}
+
+
+void Utility::clearErrorStack()
+{
+	ERR_clear_error();
+}
+
+
+} } // namespace Poco::Net