/// <summary>
/// 解析接收的数据包，形成PacketArrivedEventArgs事件数据类对象，并引发PacketArrival事件
/// </summary>
/// <param name="buf"></param>
/// <param name="len"></param>
private void Receive(byte[] buf, int len)
{
var e = PacketArrivedEventArgs.ParseFrom(buf, len);//新网络数据包信息事件
switch (e.Protocol.ToUpper())
{
case "TCP":
var te = TcpPacketArrivedEventArgs.ParseTcpFrom(buf, len);
OnPacketArrival(te);
return;
case "UDP":
var ue = UdpPacketArrivedEventArgs.ParseUdpFrom(buf, len);
OnPacketArrival(ue);
return;
}
//引发PacketArrival事件
OnPacketArrival(e);
}
/// <summary>
/// 解析TCP包
/// </summary>
/// <param name="buf"></param>
/// <param name="len"></param>
/// <returns></returns>
public unsafe static TcpPacketArrivedEventArgs ParseTcpFrom(byte[] buf, int len)
{
var e = new TcpPacketArrivedEventArgs();//新网络数据包信息事件
fixed(byte *fixedBuf = buf)
{
var head = (TcpHeader *)fixedBuf;//把数据流整和为IPHeader结构
e.HeaderLength = (uint)(head->IpHeader.IpVerLen & 0x0F) << 2;
e.TcpHeaderLength = (uint)(head->HeaderLength & 0xF0) >> 2;
var tempProtocol = head->IpHeader.IpProtocol;
switch (tempProtocol) //提取协议类型
{
case 1:
e.Protocol = "ICMP";
break;
case 2:
e.Protocol = "IGMP";
break;
case 6:
e.Protocol = "TCP";
break;
case 17:
e.Protocol = "UDP";
break;
default:
e.Protocol = "UNKNOWN";
break;
}
var tempVersion = (uint)(head->IpHeader.IpVerLen & 0xF0) >> 4;
e.IpVersion = tempVersion.ToString(CultureInfo.InvariantCulture);
//以下语句提取出了PacketArrivedEventArgs对象中的其他参数
var tempIpSrcaddr = head->IpHeader.IpSrcAddr;
var tempIpDestaddr = head->IpHeader.IpDestAddr;
var tempIp = new IPAddress(tempIpSrcaddr);
e.OriginationAddress = tempIp.ToString();
tempIp = new IPAddress(tempIpDestaddr);
e.DestinationAddress = tempIp.ToString();
var tempSrcport = *(short *)&fixedBuf[e.HeaderLength];
var tempDstport = *(short *)&fixedBuf[e.HeaderLength + 2];
e.OriginationPort = IPAddress.NetworkToHostOrder(tempSrcport).ToString(CultureInfo.InvariantCulture);
e.DestinationPort = IPAddress.NetworkToHostOrder(tempDstport).ToString(CultureInfo.InvariantCulture);
e.SerialNumber = IPAddress.NetworkToHostOrder(head->SerialNumber).ToString(CultureInfo.InvariantCulture);
e.ConfirmNumber =
IPAddress.NetworkToHostOrder(head->ConfirmNumber).ToString(CultureInfo.InvariantCulture);
e.UrgFlag = (head->TcpFlags & 0x20) >> 5 > 0;
e.AckFlag = (head->TcpFlags & 0x10) >> 4 > 0;
e.PshFlag = (head->TcpFlags & 0x08) >> 3 > 0;
e.PstFlag = (head->TcpFlags & 0x04) >> 2 > 0;
e.SynFlag = (head->TcpFlags & 0x02) >> 1 > 0;
e.FinFlag = (head->TcpFlags & 0x01) > 0;
e.WindowSize = IPAddress.NetworkToHostOrder(head->WindowSize).ToString(CultureInfo.InvariantCulture);
e.PacketLength = (uint)len;
e.MessageLength = (uint)len - e.HeaderLength;
e.TcpMessageLength = (uint)len - e.HeaderLength - e.TcpHeaderLength;
e.ReceiveBuffer = buf;
//把buf中的IP头赋给PacketArrivedEventArgs中的IPHeaderBuffer
Array.Copy(buf, 0, e.IpHeaderBuffer, 0, (int)e.HeaderLength);
//把buf中的包中内容赋给PacketArrivedEventArgs中的MessageBuffer
Array.Copy(buf, (int)e.HeaderLength, e.MessageBuffer, 0, (int)e.MessageLength);
//TCP Header;
Array.Copy(buf, (int)(e.HeaderLength), e.TcpHeaderBuffer, 0, (int)e.TcpHeaderLength);
//TCP Message;
Array.Copy(buf, (int)(e.HeaderLength + e.TcpHeaderLength), e.TcpMessageBuffer, 0,
(int)e.TcpMessageLength);
}
return(e);
}
