/// <summary>
/// 从一段数据流中从前至后查找数据包，返回第一个数据包的位置,如果出现第一个未接收完整的疑似包，
/// 而该疑似包之后没有再发现下一个数据包，则传出这个疑似包的结果。
/// </summary>
/// <param name="data"></param>
/// <param name="startIndex"></param>
/// <returns></returns>
private OnceFindResult FindPacketOnce(byte[] data, int startIndex)
{
OnceFindResult result = new OnceFindResult();
int startSuspect = 0;
bool isFindSuspect = false;
for (int i = startIndex; i < data.Length; i++)
{
result = PacketCheck(data, i);
if (result.e == PacketError.Succeed) //如果当前位置判断成功，就直接传出结果
{
return(result);
}
else if (result.e == PacketError.PacketReceiveing && isFindSuspect == false)
{
startSuspect = i;
isFindSuspect = true;
break;
}
else if (result.e == PacketError.PacketLengthTooShort && isFindSuspect == false)
{
startSuspect = i;
isFindSuspect = true;
break;
}
}
if (isFindSuspect)
{
return(PacketCheck(data, startSuspect));
}
else
{
return(result);
}
}
/// <summary>
/// 检测测数据包是否正确的功能函数。输入一个判断位置，会检测包头，长度，包尾巴，然后返回结果。
/// </summary>
/// <param name="PacketData"></param>
/// <param name="startIndex"></param>
/// <returns></returns>
private OnceFindResult PacketCheck(byte[] PacketData, int startIndex = 0)
{
OnceFindResult reslut = new OnceFindResult();
reslut.startIndex = startIndex;
if ((PacketData.Length - startIndex) < (head.Length + sizeof(int) + 0 + end.Length))
{
reslut.e = PacketError.PacketLengthTooShort;//长度就小于最小长度
return(reslut);
}
//判断包头是否正确
else if (!CheckHead(PacketData, startIndex))
{
reslut.e = PacketError.HeadError;//包头字节不对
return(reslut);
}
int length = GetLength(PacketData, startIndex);//从数据包中得到长度
if (startIndex + length > PacketData.Length)
{
reslut.e = PacketError.PacketReceiveing;//长度位数据不对，还未收完整
reslut.length = length;
return(reslut);
}
if (!CheckEnd(PacketData, startIndex, length))
{
reslut.e = PacketError.EndError;//包尾字节不对
return(reslut);
}
reslut.e = PacketError.Succeed;
reslut.length = length;
return(reslut);
}
/// <summary>
/// 输入一段有头尾的数据包，尝试拆出数据
/// </summary>
private byte[] UnPack(byte[] PData, OnceFindResult result)
{
if (result.e == PacketError.Succeed)
{
byte[] data = new byte[result.length - head.Length - sizeof(int) - sizeof(uint) - end.Length];
Buffer.BlockCopy(PData, result.startIndex + head.Length + sizeof(int), data, 0, data.Length);
return(data);
}
else
{
return(null);
}
}
byte[] IPacket.UnPack(byte[] sData, int startIndex)
{
OnceFindResult result = PacketCheck(sData, startIndex);
if (result.e == PacketError.Succeed)
{
byte[] data = new byte[result.length - head.Length - sizeof(int) - sizeof(uint) - end.Length];
Buffer.BlockCopy(sData, result.startIndex + head.Length + sizeof(int), data, 0, data.Length);
return(data);
}
else
{
return(null);
}
}
/// <summary>
/// 检测测数据包是否正确的功能函数。输入一个判断位置，会检测包头，长度，包尾巴，然后返回结果。
/// </summary>
/// <param name="PacketData"></param>
/// <param name="startIndex"></param>
/// <returns></returns>
private OnceFindResult PacketCheck(byte[] PacketData, int startIndex = 0)
{
OnceFindResult reslut = new OnceFindResult();
reslut.startIndex = startIndex;
if ((PacketData.Length - startIndex) < (head.Length + sizeof(int) + 0 + sizeof(uint) + end.Length))
{
reslut.e = PacketError.PacketLengthTooShort;//长度就小于最小长度
return(reslut);
}
//判断包头是否正确
else if (!CheckHead(PacketData, startIndex))
{
reslut.e = PacketError.HeadError;//包头字节不对
return(reslut);
}
int length = GetLength(PacketData, startIndex);
if (startIndex + length > PacketData.Length)
{
reslut.e = PacketError.PacketReceiveing;//长度位数据不对，还未收完整
reslut.length = length;
return(reslut);
}
if (!CheckEnd(PacketData, startIndex, length))
{
reslut.e = PacketError.EndError;//包尾字节不对
return(reslut);
}
//如果设置进行CRC校验才进行校验，否则不校验。
if (isCheckCRC)
{
uint crc = GetCRC(PacketData, startIndex, length);
if (crc != Crc32.Crc(PacketData, startIndex, length - end.Length - sizeof(uint)))
{
reslut.e = PacketError.CRCError;//CRC错误
return(reslut);
}
}
reslut.e = PacketError.Succeed;
reslut.length = length;
return(reslut);
}
