goreplay~tcpdump

Posted 2021-08-09 it_worker365

goreplay几种engine的区别

capture.go中的引擎类型

func (eng *EngineType) Set(v string) error {
    switch v {
    case "", "libpcap":
        *eng = EnginePcap
    case "pcap_file":
        *eng = EnginePcapFile
    case "raw_socket":
        *eng = EngineRawSocket
    case "af_packet":
        *eng = EngineAFPacket
    default:
        return fmt.Errorf("invalid engine %s", v)
    }
    return nil
}

引擎处理 pcap

func (l *Listener) activatePcap() error {
    var e error
    var msg string
    for _, ifi := range l.Interfaces {
        var handle *pcap.Handle
        handle, e = l.PcapHandle(ifi)
        if e != nil {
            msg += ("\\n" + e.Error())
            continue
        }
        l.Handles[ifi.Name] = packetHandle{
            handler: handle,
            ips:     interfaceIPs(ifi),
        }
    }
    if len(l.Handles) == 0 {
        return fmt.Errorf("pcap handles error:%s", msg)
    }
    return nil
}

不同的handler

func (l *Listener) PcapHandle(ifi pcap.Interface) (handle *pcap.Handle, err error) {
    var inactive *pcap.InactiveHandle
    inactive, err = pcap.NewInactiveHandle(ifi.Name)
    if err != nil {
        return nil, fmt.Errorf("inactive handle error: %q, interface: %q", err, ifi.Name)
    }
    defer inactive.CleanUp()

    if l.TimestampType != "" && l.TimestampType != "go" {
        var ts pcap.TimestampSource
        ts, err = pcap.TimestampSourceFromString(l.TimestampType)
        fmt.Println("Setting custom Timestamp Source. Supported values: `go`, ", inactive.SupportedTimestamps())
        err = inactive.SetTimestampSource(ts)
        if err != nil {
            return nil, fmt.Errorf("%q: supported timestamps: %q, interface: %q", err, inactive.SupportedTimestamps(), ifi.Name)
        }
    }
    if l.Promiscuous {
        if err = inactive.SetPromisc(l.Promiscuous); err != nil {
            return nil, fmt.Errorf("promiscuous mode error: %q, interface: %q", err, ifi.Name)
        }
    }
    if l.Monitor {
        if err = inactive.SetRFMon(l.Monitor); err != nil && !errors.Is(err, pcap.CannotSetRFMon) {
            return nil, fmt.Errorf("monitor mode error: %q, interface: %q", err, ifi.Name)
        }
    }

    var snap int

    if !l.Snaplen {
        infs, _ := net.Interfaces()
        for _, i := range infs {
            if i.Name == ifi.Name {
                snap = i.MTU + 200
            }
        }
    }

    if snap == 0 {
        snap = 64<<10 + 200
    }

    err = inactive.SetSnapLen(snap)
    if err != nil {
        return nil, fmt.Errorf("snapshot length error: %q, interface: %q", err, ifi.Name)
    }
    if l.BufferSize > 0 {
        err = inactive.SetBufferSize(int(l.BufferSize))
        if err != nil {
            return nil, fmt.Errorf("handle buffer size error: %q, interface: %q", err, ifi.Name)
        }
    }
    if l.BufferTimeout == 0 {
        l.BufferTimeout = 2000 * time.Millisecond
    }
    err = inactive.SetTimeout(l.BufferTimeout)
    if err != nil {
        return nil, fmt.Errorf("handle buffer timeout error: %q, interface: %q", err, ifi.Name)
    }
    handle, err = inactive.Activate()
    if err != nil {
        return nil, fmt.Errorf("PCAP Activate device error: %q, interface: %q", err, ifi.Name)
    }

    bpfFilter := l.BPFFilter
    if bpfFilter == "" {
        bpfFilter = l.Filter(ifi)
    }
    fmt.Println("Interface:", ifi.Name, ". BPF Filter:", bpfFilter)
    err = handle.SetBPFFilter(bpfFilter)
    if err != nil {
        handle.Close()
        return nil, fmt.Errorf("BPF filter error: %q%s, interface: %q", err, bpfFilter, ifi.Name)
    }
    return
}

 

表现 --input-raw-engine raw_socket 

 

 

 --input-raw-engine libpcap

 

 

 --input-raw-engine af_packet 

 

 

 

 

tcpdump监听

tcpdump tcp -i eth0 -t -s 0 -c 100 and dst port 8080 and \\(dst host 172.29.246.151 or dst host fe80::216:3eff:fe00:7e1\\)

三次请求结果

 

 

 

func (eng *EngineType) Set(v string) error {
   switch v {
   case "", "libpcap":
      *eng = EnginePcap
case "pcap_file":
      *eng = EnginePcapFile
case "raw_socket":
      *eng = EngineRawSocket
case "af_packet":
      *eng = EngineAFPacket
default:
      return fmt.Errorf("invalid engine %s", v)
   }
   return nil
}