Full Distribution

src/protocol.cpp

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+/**
+ * Tibia GIMUD Server - a free and open-source MMORPG server emulator
+ * Copyright (C) 2017  Alejandro Mujica <alejandrodemujica@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "otpch.h"
+
+#include "protocol.h"
+#include "outputmessage.h"
+#include "rsa.h"
+
+extern RSA g_RSA;
+
+void Protocol::onSendMessage(const OutputMessage_ptr& msg) const
+{
+	if (!rawMessages) {
+		msg->writeMessageLength();
+
+		if (encryptionEnabled) {
+			XTEA_encrypt(*msg);
+			msg->addCryptoHeader();
+		}
+	}
+}
+
+void Protocol::onRecvMessage(NetworkMessage& msg)
+{
+	if (encryptionEnabled && !XTEA_decrypt(msg)) {
+		return;
+	}
+
+	parsePacket(msg);
+}
+
+OutputMessage_ptr Protocol::getOutputBuffer(int32_t size)
+{
+	//dispatcher thread
+	if (!outputBuffer) {
+		outputBuffer = OutputMessagePool::getOutputMessage();
+	} else if ((outputBuffer->getLength() + size) > NetworkMessage::MAX_PROTOCOL_BODY_LENGTH) {
+		send(outputBuffer);
+		outputBuffer = OutputMessagePool::getOutputMessage();
+	}
+	return outputBuffer;
+}
+
+void Protocol::XTEA_encrypt(OutputMessage& msg) const
+{
+	const uint32_t delta = 0x61C88647;
+
+	// The message must be a multiple of 8
+	size_t paddingBytes = msg.getLength() % 8;
+	if (paddingBytes != 0) {
+		msg.addPaddingBytes(8 - paddingBytes);
+	}
+
+	uint8_t* buffer = msg.getOutputBuffer();
+	const size_t messageLength = msg.getLength();
+	size_t readPos = 0;
+	const uint32_t k[] = {key[0], key[1], key[2], key[3]};
+	while (readPos < messageLength) {
+		uint32_t v0;
+		memcpy(&v0, buffer + readPos, 4);
+		uint32_t v1;
+		memcpy(&v1, buffer + readPos + 4, 4);
+
+		uint32_t sum = 0;
+
+		for (int32_t i = 32; --i >= 0;) {
+			v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
+			sum -= delta;
+			v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[(sum >> 11) & 3]);
+		}
+
+		memcpy(buffer + readPos, &v0, 4);
+		readPos += 4;
+		memcpy(buffer + readPos, &v1, 4);
+		readPos += 4;
+	}
+}
+
+bool Protocol::XTEA_decrypt(NetworkMessage& msg) const
+{
+	if (((msg.getLength() - 2) % 8) != 0) {
+		return false;
+	}
+
+	const uint32_t delta = 0x61C88647;
+
+	uint8_t* buffer = msg.getBuffer() + msg.getBufferPosition();
+	const size_t messageLength = (msg.getLength() - 6);
+	size_t readPos = 0;
+	const uint32_t k[] = {key[0], key[1], key[2], key[3]};
+	while (readPos < messageLength) {
+		uint32_t v0;
+		memcpy(&v0, buffer + readPos, 4);
+		uint32_t v1;
+		memcpy(&v1, buffer + readPos + 4, 4);
+
+		uint32_t sum = 0xC6EF3720;
+
+		for (int32_t i = 32; --i >= 0;) {
+			v1 -= ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[(sum >> 11) & 3]);
+			sum += delta;
+			v0 -= ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
+		}
+
+		memcpy(buffer + readPos, &v0, 4);
+		readPos += 4;
+		memcpy(buffer + readPos, &v1, 4);
+		readPos += 4;
+	}
+
+	int innerLength = msg.get<uint16_t>();
+	if (innerLength > msg.getLength() - 4) {
+		return false;
+	}
+
+	msg.setLength(innerLength);
+	return true;
+}
+
+bool Protocol::RSA_decrypt(NetworkMessage& msg)
+{
+	if ((msg.getLength() - msg.getBufferPosition()) < 128) {
+		return false;
+	}
+
+	g_RSA.decrypt(reinterpret_cast<char*>(msg.getBuffer()) + msg.getBufferPosition()); //does not break strict aliasing
+	return msg.getByte() == 0;
+}
+
+uint32_t Protocol::getIP() const
+{
+	if (auto connection = getConnection()) {
+		return connection->getIP();
+	}
+
+	return 0;
+}