113 lines
2.8 KiB
C++
113 lines
2.8 KiB
C++
#pragma once
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#include "Common.h"
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#include "util/ByteUtil.h"
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#include <cstdio>
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#include <cstdint>
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#include <string>
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using std::string;
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namespace Feather
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{
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// Class to read packet data, such as is produced by NetworkMessage
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class PacketReader
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{
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public:
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PacketReader(const uint8_t *const dataPtr)
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: m_data(dataPtr), m_offset(0), m_length(ReadLength())
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{
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}
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// Peek the next value to be read
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// If big endian (the default), will reverse byte order.
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template <typename T, Endian endianMode = Endian::Big>
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inline T Peek()
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{
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T value = *reinterpret_cast<const T *const>(&m_data[m_offset]);
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return (endianMode == Endian::Big) ? ReverseBytes<T>(value) : value;
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}
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// Read the next value
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// If big endian (the default), will reverse byte order.
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template <typename T, Endian endianMode = Endian::Big>
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inline T Read()
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{
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T value = Peek<T, endianMode>();
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m_offset += sizeof(T);
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return value;
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}
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// Fast way to peek the next byte
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inline uint8_t PeekByte() { return m_data[m_offset]; }
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// Fast way to read a byte
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inline uint8_t ReadByte() { return m_data[m_offset++]; }
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inline int32_t ReadLength()
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{
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int32_t length = ReadVarInt();
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// HACK: handle Legacy Server List Ping
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if (length == 0xFE) {
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if (PeekByte() == 0x01) {
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return 2;
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}
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}
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return length;
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}
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template <typename T = int32_t>
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inline T ReadVarInt()
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{
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int32_t numRead = 0;
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int32_t result = 0;
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uint8_t read;
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do
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{
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read = ReadByte();
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int value = (read & 0b01111111);
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result |= (value << (7 * numRead));
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numRead++;
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if (numRead > 5)
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{
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// complain
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//throw new RuntimeException("VarInt is too big");
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}
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} while ((read & 0b10000000) != 0);
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return static_cast<T>(result);
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}
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string ReadString()
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{
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int size = ReadVarInt();
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string str;
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for (int i = 0; i < size; i++) {
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str += ReadByte();
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}
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return str;
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}
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uint32_t Length() const { return m_length; }
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private:
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const uint8_t *const m_data;
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uint32_t m_offset;
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const uint32_t m_length;
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};
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// Use fast Read and Peek for uint8_t
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template <>
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inline uint8_t PacketReader::Peek<uint8_t>() { return PeekByte(); }
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template<>
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inline uint8_t PacketReader::Read<uint8_t>() { return ReadByte(); }
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}
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