tcp.go

package ztrace

import (
	"encoding/binary"
	"math/rand"
	"net"
	"time"

	"github.com/sirupsen/logrus"
	"golang.org/x/net/ipv4"
)

func (t *TraceRoute) SendIPv4TCP() error {
	dport := t.TCPDPort
	sport := uint16(1000 + t.PortOffset + rand.Int31n(500))

	key := GetHash(t.NetSrcAddr.To4(), t.NetDstAddr.To4(), sport, dport, 6)
	db := NewStatsDB(key)

	t.DB.Store(key, db)
	go db.Cache.Run()
	conn, err := net.ListenPacket("ip4:tcp", t.NetSrcAddr.String())
	if err != nil {
		logrus.Error(err)
		return err
	}
	defer conn.Close()

	rSocket, err := ipv4.NewRawConn(conn)
	if err != nil {
		logrus.Error("can not create raw socket:", err)
		return err
	}
	defer rSocket.Close()

	seq := uint32(1000)
	mod := uint32(1 << 30)

	for ttl := 1; ttl <= int(t.MaxTTL); ttl++ {
		hdr, payload := t.BuildIPv4TCPSYN(sport, dport, uint8(ttl), seq, 0)
		rSocket.WriteTo(hdr, payload, nil)

		m := &SendMetric{
			FlowKey:   key,
			ID:        seq,
			TTL:       uint8(ttl),
			TimeStamp: time.Now(),
		}
		seq = (seq + 4) % mod

		t.RecordSend(m)
	}
	t.StartTime = time.Now()

	return nil
}

func (t *TraceRoute) ListenIPv4TCP_ICMP() error {
	laddr := &net.IPAddr{IP: t.NetSrcAddr}
	var err error

	t.recvICMPConn, err = net.ListenIP("ip4:icmp", laddr)
	if err != nil {
		logrus.Error("bind failure:", err)
		return err
	}
	defer t.recvICMPConn.Close()

	t.recvICMPConn.SetReadDeadline(time.Now().Add(t.Timeout))

	for {
		buf := make([]byte, 1500)

		n, raddr, err := t.recvICMPConn.ReadFrom(buf)
		if err != nil {
			break
		}

		icmpType := buf[0]

		if (raddr.String() == t.NetDstAddr.String() || icmpType == 11 || (icmpType == 3 && buf[1] == 3)) && (n >= 36) {
			seq := binary.BigEndian.Uint32(buf[32:36])
			dstip := net.IP(buf[24:28])
			srcip := net.IP(buf[20:24])
			srcPort := binary.BigEndian.Uint16(buf[28:30])
			dstPort := binary.BigEndian.Uint16(buf[30:32])

			if dstip.Equal(t.NetDstAddr) {
				key := GetHash(srcip, dstip, srcPort, dstPort, 6)

				m := &RecvMetric{
					FlowKey:   key,
					ID:        seq,
					RespAddr:  raddr.String(),
					TimeStamp: time.Now(),
				}

				t.RecordRecv(m)
			}
		}
	}

	t.Statistics()

	return nil
}