/// <summary>
/// 解析请求的数据
/// 返回请求数据包
/// </summary>
/// <param name="builder">所有收到的数据</param>
/// <param name="resultBuilder">用于保存数理后的数据</param>
/// <returns></returns>
public unsafe static Hybi13Packet GetPacket(ByteBuilder builder, ByteBuilder resultBuilder)
{
if (builder.Length < 2)
{
return(null);
}
var isFinal = (builder.ToByte(0) & 128) != 0;
var reservedBits = builder.ToByte(0) & 112;
var frameType = (FrameTypes)(builder.ToByte(0) & 15);
var isMasked = (builder.ToByte(1) & 128) != 0;
var length = builder.ToByte(1) & 127;
if (isMasked == false || Enum.IsDefined(typeof(FrameTypes), frameType) == false || reservedBits != 0)
{
return(null);
}
// 计算数据长度和mask索引
var maskIndex = 2;
if (length == 127)
{
if (builder.Length < maskIndex + 8)
{
return(null);
}
length = (int)builder.ToUInt64(maskIndex, Endians.Big);
maskIndex = maskIndex + 8;
}
else if (length == 126)
{
if (builder.Length < maskIndex + 2)
{
return(null);
}
length = (int)builder.ToUInt16(maskIndex, Endians.Big);
maskIndex = maskIndex + 2;
}
// 检查数据长度
if (builder.Length < maskIndex + Math.Max(4, length))
{
return(null);
}
// 数据内容的索引位置
var dataIndex = maskIndex + 4;
if (length > 0)
{
fixed(byte *pdata = &builder.Source[dataIndex], pmask = &builder.Source[maskIndex])
{
for (var i = 0; i < length; i++)
{
*(pdata + i) = (byte)(*(pdata + i) ^ *(pmask + i % 4));
}
}
}
// 将数据放到resultBuilder
resultBuilder.Add(builder.Source, dataIndex, length);
// 清除已分析的数据
builder.Remove(dataIndex + length);
// 检查数据是否传输完成
if (isFinal == true && frameType != FrameTypes.Continuation)
{
var bytes = resultBuilder.ToArrayThenClear();
return(new RequestPacket(frameType, bytes));
}
else
{
return(null);
}
}