Full Distribution

src/networkmessage.h

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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.
+ */
+
+#ifndef FS_NETWORKMESSAGE_H_B853CFED58D1413A87ACED07B2926E03
+#define FS_NETWORKMESSAGE_H_B853CFED58D1413A87ACED07B2926E03
+
+#include "const.h"
+
+class Item;
+class Creature;
+class Player;
+struct Position;
+class RSA;
+
+class NetworkMessage
+{
+	public:
+		typedef uint16_t MsgSize_t;
+		// Headers:
+		// 2 bytes for unencrypted message size
+		// 2 bytes for encrypted message size
+		static constexpr MsgSize_t INITIAL_BUFFER_POSITION = 4;
+		enum { HEADER_LENGTH = 2 };
+		enum { XTEA_MULTIPLE = 8 };
+		enum { MAX_BODY_LENGTH = NETWORKMESSAGE_MAXSIZE - HEADER_LENGTH - XTEA_MULTIPLE };
+		enum { MAX_PROTOCOL_BODY_LENGTH = MAX_BODY_LENGTH - 10 };
+
+		NetworkMessage() = default;
+
+		void reset() {
+			info = {};
+		}
+
+		// simply read functions for incoming message
+		uint8_t getByte() {
+			if (!canRead(1)) {
+				return 0;
+			}
+
+			return buffer[info.position++];
+		}
+
+		uint8_t getPreviousByte() {
+			return buffer[--info.position];
+		}
+
+		template<typename T>
+		T get() {
+			if (!canRead(sizeof(T))) {
+				return 0;
+			}
+
+			T v;
+			memcpy(&v, buffer + info.position, sizeof(T));
+			info.position += sizeof(T);
+			return v;
+		}
+
+		std::string getString(uint16_t stringLen = 0);
+		Position getPosition();
+
+		// skips count unknown/unused bytes in an incoming message
+		void skipBytes(int16_t count) {
+			info.position += count;
+		}
+
+		// simply write functions for outgoing message
+		void addByte(uint8_t value) {
+			if (!canAdd(1)) {
+				return;
+			}
+
+			buffer[info.position++] = value;
+			info.length++;
+		}
+
+		template<typename T>
+		void add(T value) {
+			if (!canAdd(sizeof(T))) {
+				return;
+			}
+
+			memcpy(buffer + info.position, &value, sizeof(T));
+			info.position += sizeof(T);
+			info.length += sizeof(T);
+		}
+
+		void addBytes(const char* bytes, size_t size);
+		void addPaddingBytes(size_t n);
+
+		void addString(const std::string& value);
+
+		void addDouble(double value, uint8_t precision = 2);
+
+		// write functions for complex types
+		void addPosition(const Position& pos);
+		void addItem(uint16_t id, uint8_t count);
+		void addItem(const Item* item);
+		void addItemId(uint16_t itemId);
+
+		MsgSize_t getLength() const {
+			return info.length;
+		}
+
+		void setLength(MsgSize_t newLength) {
+			info.length = newLength;
+		}
+
+		MsgSize_t getBufferPosition() const {
+			return info.position;
+		}
+
+		uint16_t getLengthHeader() const {
+			return static_cast<uint16_t>(buffer[0] | buffer[1] << 8);
+		}
+
+		bool isOverrun() const {
+			return info.overrun;
+		}
+
+		uint8_t* getBuffer() {
+			return buffer;
+		}
+
+		const uint8_t* getBuffer() const {
+			return buffer;
+		}
+
+		uint8_t* getBodyBuffer() {
+			info.position = 2;
+			return buffer + HEADER_LENGTH;
+		}
+
+	protected:
+		inline bool canAdd(size_t size) const {
+			return (size + info.position) < MAX_BODY_LENGTH;
+		}
+
+		inline bool canRead(int32_t size) {
+			if ((info.position + size) > (info.length + 8) || size >= (NETWORKMESSAGE_MAXSIZE - info.position)) {
+				info.overrun = true;
+				return false;
+			}
+			return true;
+		}
+
+		struct NetworkMessageInfo {
+			MsgSize_t length = 0;
+			MsgSize_t position = INITIAL_BUFFER_POSITION;
+			bool overrun = false;
+		};
+
+		NetworkMessageInfo info;
+		uint8_t buffer[NETWORKMESSAGE_MAXSIZE];
+};
+
+#endif // #ifndef __NETWORK_MESSAGE_H__