Method Reject

tcp.go:204–246

Reject sends a RST packet. It is only valid to call this once, when the stream state is SynReceived

()

// Reject sends a RST packet. It is only valid to call this once, when the stream state is SynReceived
func (s *tcpStream) Reject() {
	// reply to the subprocess as if the connection were already good to go
	replytcp := layers.TCP{
		SrcPort: layers.TCPPort(s.world.Port),
		DstPort: layers.TCPPort(s.subprocess.Port),
		RST:     true,
		ACK:     true,
		Seq:     atomic.AddUint32(&s.seq, 1) - 1,
		Ack:     atomic.LoadUint32(&s.ack) + 1,
		Window:  64240, // number of bytes we are willing to receive
	}

	replyipv4 := layers.IPv4{
		Version:  4, // indicates IPv4
		TTL:      ttl,
		Protocol: layers.IPProtocolTCP,
		SrcIP:    s.world.Addr,
		DstIP:    s.subprocess.Addr,
	}

	replytcp.SetNetworkLayerForChecksum(&replyipv4)

	// log
	verbosef("sending RST to subprocess: %s", summarizeTCP(&replyipv4, &replytcp, nil))

	// serialize the packet
	serialized, err := serializeTCP(&replyipv4, &replytcp, nil, s.serializeBuf)
	if err != nil {
		errorf("error serializing reply TCP: %w, dropping", err)
		return
	}

	// make a copy of the data
	cp := make([]byte, len(serialized))
	copy(cp, serialized)

	// send to the channel that goes to the subprocess
	select {
	case s.toSubprocess <- cp:
	default:
		verbosef("channel for sending to subprocess would have blocked, dropping %d bytes", len(cp))
	}
}

// Read reads packets sent by the subprocess and intercepted by us
func (s *tcpStream) Read(buf []byte) (int, error) {