private bool PrivateIcmpInput(IPFrame packet)
{
IcmpFrame frame = IcmpLayer.ParseFrame(packet, false);
if (frame == null)
{
return(false);
}
NATContext context = this.m_contextsIcmp.PrivateInput(frame.Source, frame.Destination, frame.Identification);
if (context == null)
{
return(false);
}
IcmpFrame convertional = null;
int ttl = frame.Ttl - 1;
if (ttl <= 0)
{
convertional = new IcmpFrame(this.m_ethernetAddress, frame.Source, IPv4Layer.ToArray(packet))
{
Ttl = packet.Ttl,
Type = IcmpType.ICMP_TE,
Code = 0,
Sequence = 0,
Identification = 0,
};
IPFrame replay = CopyFrameHeaderParts(IcmpLayer.ToIPFrame(convertional), packet);
if (replay == null)
{
return(false);
}
return(this.OnPrivateOutput(replay));
}
else
{
convertional = new IcmpFrame(this.m_ethernetAddress, frame.Destination, frame.Payload)
{
Ttl = ttl,
Type = frame.Type,
Code = frame.Code,
Sequence = frame.Sequence,
Identification = frame.Identification /*unchecked((ushort)context.Destination.Port)*/,
};
}
IPFrame ip = CopyFrameHeaderParts(IcmpLayer.ToIPFrame(convertional), packet);
if (ip == null)
{
return(false);
}
return(this.OnPublicOutput(ip));
}
protected virtual bool PrivateOutput(IPFrame packet)
{
if (packet == null)
{
return(false);
}
return(this.Send(packet.Destination, () =>
new SkylakeNATMessage(IPv4Layer.ToArray(packet))
{
Commands = Commands.NATCommands_kEthernetInput,
}));
}
protected virtual ILayer ParseFrameToLayer(IPFrame frame)
{
BufferSegment packet = IPv4Layer.ToArray(frame);
if (packet == null)
{
return(null);
}
return(new PayloadLayer()
{
Data = new Datagram(packet.Buffer, packet.Offset, packet.Length)
});
}
protected virtual void NetifLevel2LayerIPv4(EthernetDatagram datagram, IpV4Datagram ip)
{
byte[] packet_data = g_getIPv4DatagramBuffer(ip);
int packet_offset = g_getIPv4DatagramOffset(ip);
int packet_size = ip.Length;
if (packet_size > 0)
{
IPFrame frame = IPv4Layer.ParseFrame(new BufferSegment(packet_data, packet_offset, packet_size), true);
if (frame != null)
{
frame.SourceMacAddress = datagram.Source;
frame.DestinationMacAddress = datagram.Destination;
this.OnSniffer(frame);
}
}
}
public virtual bool Output(IPFrame frame)
{
if (frame == null)
{
return(false);
}
lock (this.m_syncobj)
{
if (this.m_disposed)
{
return(false);
}
}
if (this.SupportTwoLayerLinks)
{
#if NO_USAGE_PCAP_NET
return(false);
#else
IList <ILayer> layers = ParseFrameToLayers(frame);
if (layers == null || layers.Count <= 0)
{
return(false);
}
MacAddress sources = frame.SourceMacAddress;
MacAddress destination = frame.DestinationMacAddress;
if (sources == MinMacAddress)
{
sources = SelectMacAddress(frame.Source);
}
if (destination == MinMacAddress)
{
destination = SelectMacAddress(frame.Destination);
}
return(this.SendNetifLevel2Output(layers: layers,
source: sources,
destination: destination));
#endif
}
else
{
return(this.SendNetifLevel3Output(packet: IPv4Layer.ToArray(frame)));
}
}
protected virtual IList <ILayer> ParseFrameToLayers(IPFrame frame)
{
if (frame == null)
{
throw new ArgumentNullException(nameof(frame));
}
IList <ILayer> layers = new List <ILayer>();
BufferSegment packet = IPv4Layer.ToArray(frame);
if (packet != null)
{
layers.Add(new PayloadLayer()
{
Data = new Datagram(packet.Buffer, packet.Offset, packet.Length)
});
}
return(layers);
}
protected virtual void ProcessMessage(SkylakeNATClient socket, SkylakeNATMessage message)
{
if (message.Commands == Commands.NATCommands_kEthernetOutput)
{
IPFrame packet = IPv4Layer.ParseFrame(message.Payload, false);
if (packet != null)
{
if (this._sockets.ContainsKey(packet.Source))
{
this.PrivateInput(socket, packet);
}
else
{
this.CloseManyClient(socket.Address);
}
}
}
}
private bool PublicIcmpNATOutput(NATContext context, IcmpFrame frame, IPFrame packet)
{
if (context == null || frame == null || packet == null)
{
return(false);
}
if (frame.Type != IcmpType.ICMP_ER) // TIME EXCEEDED
{
IPFrame ipAgo = IPv4Layer.ParseFrame(frame.Payload, false);
IcmpFrame icmpAgo = IcmpLayer.ParseFrame(ipAgo, false);
if (icmpAgo == null) // 这是一个伪造的ICMP数据报，正确报文应答必须要包含从本机发向对端主机的ICMP/IP数据报文
{
return(false);
}
ipAgo = CopyFrameHeaderParts(IcmpLayer.ToIPFrame(new IcmpFrame(frame.Source, context.Sources.Address, icmpAgo.Payload) // 重新汇编整个ICMP/IP数据报文
{
Ttl = icmpAgo.Ttl,
Type = icmpAgo.Type,
Code = icmpAgo.Code,
Sequence = icmpAgo.Sequence,
Identification = unchecked ((ushort)context.Sources.Port), // 客户端ICMP协议请求时的凭证编号
}), ipAgo);
frame.Payload = IPv4Layer.ToArray(ipAgo);
}
var convertional = new IcmpFrame(frame.Source, context.Sources.Address, frame.Payload)
{
Ttl = frame.Ttl - 1,
Type = frame.Type,
Code = frame.Code,
Sequence = frame.Sequence,
Identification = frame.Identification,
};
IPFrame ip = CopyFrameHeaderParts(IcmpLayer.ToIPFrame(convertional), packet);
if (ip == null)
{
return(false);
}
return(this.OnPrivateOutput(ip));
}
public virtual void Listen()
{
while (true)
{
lock (this.m_syncobj)
{
if (this.m_disposed)
{
break;
}
}
if (this.SupportTwoLayerLinks)
{
#if !NO_USAGE_PCAP_NET
// Retrieve the packets
PacketCommunicatorReceiveResult result = this.m_packetCommunicator.ReceivePacket(out Packet packet);
switch (result)
{
case PacketCommunicatorReceiveResult.Timeout:
// Timeout elapsed
continue;
case PacketCommunicatorReceiveResult.Ok:
{
EthernetDatagram datagram = packet.Ethernet; // 以太网数据报
switch (datagram.EtherType)
{
case EthernetType.IpV4:
NetifLevel2LayerIPv4(datagram, datagram.IpV4);
break;
case EthernetType.IpV6:
break;
case EthernetType.Arp:
NetifLevel2LayerArp(datagram, datagram.Arp);
break;
default:
break;
}
}
break;
default:
break;
}
#endif
}
else
{
int packet_size = 0;
try
{
EndPoint localEP = this.m_socket.LocalEndPoint;
packet_size = this.m_socket.ReceiveFrom(this.m_buffer, 0, this.m_buffer.Length, SocketFlags.None, ref localEP);
}
catch (Exception)
{
continue;
}
if (packet_size <= 0)
{
continue;
}
IPFrame frame = IPv4Layer.ParseFrame(new BufferSegment(this.m_buffer, 0, packet_size), true);
if (frame != null)
{
this.OnSniffer(frame);
}
}
}
}
