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/Net/src/POP3ClientSession.cpp

@@ -0,0 +1,280 @@
+//
+// POP3ClientSession.cpp
+//
+// Library: Net
+// Package: Mail
+// Module:  POP3ClientSession
+//
+// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// SPDX-License-Identifier:	BSL-1.0
+//
+
+
+#include "Poco/Net/POP3ClientSession.h"
+#include "Poco/Net/MailMessage.h"
+#include "Poco/Net/MailStream.h"
+#include "Poco/Net/SocketAddress.h"
+#include "Poco/Net/NetException.h"
+#include "Poco/StreamCopier.h"
+#include "Poco/NumberFormatter.h"
+#include "Poco/UnbufferedStreamBuf.h"
+#include "Poco/Ascii.h"
+#include <istream>
+
+
+using Poco::NumberFormatter;
+using Poco::StreamCopier;
+
+
+namespace Poco {
+namespace Net {
+
+
+class DialogStreamBuf: public Poco::UnbufferedStreamBuf
+{
+public:
+	DialogStreamBuf(DialogSocket& socket):
+		_socket(socket)
+	{
+	}
+	
+	~DialogStreamBuf()
+	{
+	}
+		
+private:
+	int readFromDevice()
+	{
+		return _socket.get();
+	}
+	
+	DialogSocket& _socket;
+};
+
+
+class DialogIOS: public virtual std::ios
+{
+public:
+	DialogIOS(DialogSocket& socket):
+		_buf(socket)
+	{
+		poco_ios_init(&_buf);
+	}
+	
+	~DialogIOS()
+	{
+	}
+	
+	DialogStreamBuf* rdbuf()
+	{
+		return &_buf;
+	}
+
+protected:
+	DialogStreamBuf _buf;
+};
+
+
+class DialogInputStream: public DialogIOS, public std::istream
+{
+public:
+	DialogInputStream(DialogSocket& socket):
+		DialogIOS(socket),
+		std::istream(&_buf)
+	{
+	}
+		
+	~DialogInputStream()
+	{
+	}
+};
+
+
+POP3ClientSession::POP3ClientSession(const StreamSocket& socket):
+	_socket(socket),
+	_isOpen(true)
+{
+}
+
+
+POP3ClientSession::POP3ClientSession(const std::string& host, Poco::UInt16 port):	
+	_socket(SocketAddress(host, port)),
+	_isOpen(true)
+{
+}
+
+
+POP3ClientSession::~POP3ClientSession()
+{
+	try
+	{
+		close();
+	}
+	catch (...)
+	{
+	}
+}
+
+
+void POP3ClientSession::setTimeout(const Poco::Timespan& timeout)
+{
+	_socket.setReceiveTimeout(timeout);
+}
+
+	
+Poco::Timespan POP3ClientSession::getTimeout() const
+{
+	return _socket.getReceiveTimeout();
+}
+
+
+void POP3ClientSession::login(const std::string& username, const std::string& password)
+{
+	std::string response;
+	_socket.receiveMessage(response);
+	if (!isPositive(response)) throw POP3Exception("The POP3 service is unavailable", response);
+	sendCommand("USER", username, response);
+	if (!isPositive(response)) throw POP3Exception("Login rejected for user", response);
+	sendCommand("PASS", password, response);
+	if (!isPositive(response)) throw POP3Exception("Password rejected for user", response);
+}
+
+
+void POP3ClientSession::close()
+{
+	if (_isOpen)
+	{
+		std::string response;
+		sendCommand("QUIT", response);
+		_socket.close();
+		_isOpen = false;
+	}
+}
+
+
+int POP3ClientSession::messageCount()
+{
+	std::string response;
+	sendCommand("STAT", response);
+	if (!isPositive(response)) throw POP3Exception("Cannot determine message count", response);
+	std::string::const_iterator it  = response.begin();
+	std::string::const_iterator end = response.end();
+	int count = 0;
+	while (it != end && !Poco::Ascii::isSpace(*it)) ++it;
+	while (it != end && Poco::Ascii::isSpace(*it)) ++it;
+	while (it != end && Poco::Ascii::isDigit(*it)) count = count*10 + *it++ - '0';
+	return count;
+}
+
+
+void POP3ClientSession::listMessages(MessageInfoVec& messages)
+{
+	messages.clear();
+	std::string response;
+	sendCommand("LIST", response);
+	if (!isPositive(response)) throw POP3Exception("Cannot get message list", response);
+	_socket.receiveMessage(response);
+	while (response != ".")
+	{
+		MessageInfo info = {0, 0};
+		std::string::const_iterator it  = response.begin();
+		std::string::const_iterator end = response.end();
+		while (it != end && Poco::Ascii::isDigit(*it)) info.id = info.id*10 + *it++ - '0';
+		while (it != end && Poco::Ascii::isSpace(*it)) ++it;
+		while (it != end && Poco::Ascii::isDigit(*it)) info.size = info.size*10 + *it++ - '0';
+		messages.push_back(info);
+		_socket.receiveMessage(response);
+	}
+}
+
+
+void POP3ClientSession::retrieveMessage(int id, MailMessage& message)
+{
+	std::string response;
+	sendCommand("RETR", NumberFormatter::format(id), response);
+	if (!isPositive(response)) throw POP3Exception("Cannot retrieve message", response);
+	DialogInputStream sis(_socket);
+	MailInputStream mis(sis);
+	message.read(mis);
+	while (mis.good()) mis.get(); // read any remaining junk
+}
+
+
+void POP3ClientSession::retrieveMessage(int id, MailMessage& message, PartHandler& handler)
+{
+	std::string response;
+	sendCommand("RETR", NumberFormatter::format(id), response);
+	if (!isPositive(response)) throw POP3Exception("Cannot retrieve message", response);
+	DialogInputStream sis(_socket);
+	MailInputStream mis(sis);
+	message.read(mis, handler);
+	while (mis.good()) mis.get(); // read any remaining junk
+}
+
+
+void POP3ClientSession::retrieveMessage(int id, std::ostream& ostr)
+{
+	std::string response;
+	sendCommand("RETR", NumberFormatter::format(id), response);
+	if (!isPositive(response)) throw POP3Exception("Cannot retrieve message", response);
+	DialogInputStream sis(_socket);
+	MailInputStream mis(sis);
+	StreamCopier::copyStream(mis, ostr);
+}
+
+
+void POP3ClientSession::retrieveHeader(int id, MessageHeader& header)
+{
+	std::string response;
+	sendCommand("TOP", NumberFormatter::format(id), "0", response);
+	if (!isPositive(response)) throw POP3Exception("Cannot retrieve header", response);
+	DialogInputStream sis(_socket);
+	MailInputStream mis(sis);
+	header.read(mis);
+	// skip stuff following header
+	mis.get(); // \r
+	mis.get(); // \n
+}
+
+
+void POP3ClientSession::deleteMessage(int id)
+{
+	std::string response;
+	sendCommand("DELE", NumberFormatter::format(id), response);
+	if (!isPositive(response)) throw POP3Exception("Cannot mark message for deletion", response);
+}
+
+
+bool POP3ClientSession::sendCommand(const std::string& command, std::string& response)
+{
+	_socket.sendMessage(command);
+	_socket.receiveMessage(response);
+	return isPositive(response);
+}
+
+
+bool POP3ClientSession::sendCommand(const std::string& command, const std::string& arg, std::string& response)
+{
+	_socket.sendMessage(command, arg);
+	_socket.receiveMessage(response);
+	return isPositive(response);
+}
+
+
+bool POP3ClientSession::sendCommand(const std::string& command, const std::string& arg1, const std::string& arg2, std::string& response)
+{
+	_socket.sendMessage(command, arg1, arg2);
+	_socket.receiveMessage(response);
+	return isPositive(response);
+}
+
+
+bool POP3ClientSession::isPositive(const std::string& response)
+{
+	return response.length() > 0 && response[0] == '+';
+}
+
+
+} } // namespace Poco::Net