FurinaImpact/FurinaImpact.Gameserver/Network/NetPacket.cs

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2023-12-09 03:45:08 +00:00
using System.Buffers.Binary;
using FurinaImpact.Protocol;
using Google.Protobuf;
namespace FurinaImpact.Gameserver.Network;
internal class NetPacket
{
private const ushort HeadMagic = 0x4567;
private const ushort TailMagic = 0x89AB;
public CmdType CmdType { get; set; }
public Memory<byte> Head { get; set; }
public Memory<byte> Body { get; set; }
public TBody DecodeBody<TBody>() where TBody : IMessage<TBody>, new()
{
return new MessageParser<TBody>(() => new()).ParseFrom(Body.Span);
}
public int EncodeTo(Memory<byte> buffer)
{
Span<byte> span = buffer.Span;
BinaryPrimitives.WriteUInt16BigEndian(span[0..2], HeadMagic);
BinaryPrimitives.WriteUInt16BigEndian(span[2..4], (ushort)CmdType);
BinaryPrimitives.WriteUInt16BigEndian(span[4..6], (ushort)Head.Length);
BinaryPrimitives.WriteInt32BigEndian(span[6..10], Body.Length);
Head.CopyTo(buffer[10..]);
Body.CopyTo(buffer[(10 + Head.Length)..]);
BinaryPrimitives.WriteUInt16BigEndian(span[(10 + Head.Length + Body.Length)..], TailMagic);
return 12 + Head.Length + Body.Length;
}
public static (NetPacket?, int) DecodeFrom(Memory<byte> data)
{
ReadOnlySpan<byte> span = data.Span;
ushort headMagic = BinaryPrimitives.ReadUInt16BigEndian(span[0..2]);
if (headMagic != HeadMagic)
return (null, 0);
ushort cmdType = BinaryPrimitives.ReadUInt16BigEndian(span[2..4]);
int headLength = BinaryPrimitives.ReadUInt16BigEndian(span[4..6]);
int bodyLength = BinaryPrimitives.ReadInt32BigEndian(span[6..10]);
if (data.Length < 12 + headLength + bodyLength)
return (null, 0);
Memory<byte> head = data.Slice(10, headLength);
Memory<byte> body = data.Slice(10 + headLength, bodyLength);
ushort tailMagic = BinaryPrimitives.ReadUInt16BigEndian(span[(10 + headLength + bodyLength)..]);
if (tailMagic != TailMagic)
return (null, 0);
NetPacket netPacket = new()
{
CmdType = (CmdType)cmdType,
Head = head,
Body = body
};
return (netPacket, 12 + headLength + bodyLength);
}
}