Golang TCP.Seq方法代码示例

func BenchmarkSingleStreamSkips(b *testing.B) {
	t := layers.TCP{
		SrcPort:   1,
		DstPort:   2,
		SYN:       true,
		Seq:       1000,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
	}
	a := NewAssembler(NewStreamPool(&testFactory{}))
	skipped := false
	for i := 0; i < b.N; i++ {
		if i%10 == 9 {
			t.Seq += 10
			skipped = true
		} else if skipped {
			t.Seq -= 20
		}
		a.Assemble(netFlow, &t)
		if t.SYN {
			t.SYN = false
			t.Seq++
		}
		t.Seq += 10
		if skipped {
			t.Seq += 10
			skipped = false
		}
	}
}

func BenchmarkMultiStreamConn(b *testing.B) {
	t := layers.TCP{
		SrcPort:   1,
		DstPort:   2,
		Seq:       0,
		SYN:       true,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
	}
	a := NewAssembler(NewStreamPool(&testFactory{}))
	for i := 0; i < b.N; i++ {
		t.SrcPort = layers.TCPPort(i)
		a.Assemble(netFlow, &t)
		if i%65536 == 65535 {
			if t.SYN {
				t.SYN = false
				t.Seq += 1
			}
			t.Seq += 10
		}
	}
}

func BenchmarkMultiStreamGrow(b *testing.B) {
	t := layers.TCP{
		SrcPort:   1,
		DstPort:   2,
		Seq:       0,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
	}
	a := NewAssembler(NewStreamPool(&testFactory{}))
	for i := 0; i < b.N; i++ {
		t.SrcPort = layers.TCPPort(i)
		a.Assemble(netFlow, &t)
		t.Seq += 10
	}
}

func BenchmarkSingleStreamLoss(b *testing.B) {
	t := layers.TCP{
		SrcPort:   1,
		DstPort:   2,
		SYN:       true,
		Seq:       1000,
		BaseLayer: layers.BaseLayer{Payload: []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
	}
	a := NewAssembler(NewStreamPool(&testFactory{}))
	for i := 0; i < b.N; i++ {
		a.Assemble(netFlow, &t)
		t.SYN = false
		t.Seq += 11
	}
}

func (tcp *Tcp) Process(id *flows.FlowID, tcphdr *layers.TCP, pkt *protos.Packet) {
	// This Recover should catch all exceptions in
	// protocol modules.
	defer logp.Recover("Process tcp exception")

	stream, created := tcp.getStream(pkt)
	if stream.conn == nil {
		return
	}

	conn := stream.conn
	if id != nil {
		id.AddConnectionID(uint64(conn.id))
	}

	if isDebug {
		debugf("tcp flow id: %p", id)
	}

	if len(pkt.Payload) == 0 && !tcphdr.FIN {
		// return early if packet is not interesting. Still need to find/create
		// stream first in order to update the TCP stream timer
		return
	}

	tcpStartSeq := tcphdr.Seq
	tcpSeq := tcpStartSeq + uint32(len(pkt.Payload))
	lastSeq := conn.lastSeq[stream.dir]
	if isDebug {
		debugf("pkt.start_seq=%v pkt.last_seq=%v stream.last_seq=%v (len=%d)",
			tcpStartSeq, tcpSeq, lastSeq, len(pkt.Payload))
	}

	if len(pkt.Payload) > 0 && lastSeq != 0 {
		if tcpSeqBeforeEq(tcpSeq, lastSeq) {
			if isDebug {
				debugf("Ignoring retransmitted segment. pkt.seq=%v len=%v stream.seq=%v",
					tcphdr.Seq, len(pkt.Payload), lastSeq)
			}
			return
		}

		switch tcpSeqCompare(lastSeq, tcpStartSeq) {
		case seqLT: // lastSeq < tcpStartSeq => Gap in tcp stream detected
			if created {
				break
			}

			gap := int(tcpStartSeq - lastSeq)
			debugf("Gap in tcp stream. last_seq: %d, seq: %d, gap: %d", lastSeq, tcpStartSeq, gap)
			drop := stream.gapInStream(gap)
			if drop {
				if isDebug {
					debugf("Dropping connection state because of gap")
				}
				droppedBecauseOfGaps.Add(1)

				// drop application layer connection state and
				// update stream_id for app layer analysers using stream_id for lookups
				conn.id = tcp.getId()
				conn.data = nil
			}

		case seqGT:
			// lastSeq > tcpStartSeq => overlapping TCP segment detected. shrink packet
			delta := lastSeq - tcpStartSeq

			if isDebug {
				debugf("Overlapping tcp segment. last_seq %d, seq: %d, delta: %d",
					lastSeq, tcpStartSeq, delta)
			}

			pkt.Payload = pkt.Payload[delta:]
			tcphdr.Seq += delta
		}
	}

	conn.lastSeq[stream.dir] = tcpSeq
	stream.addPacket(pkt, tcphdr)
}