// gopacket is a simple example showing how to answer APR and ICMP echo // requests through a memif interface. This example is mostly identical // to icmp-responder example, but it is using MemifPacketHandle API to // read and write packets using gopacket API. // // The appropriate VPP configuration for the opposite memif is: // vpp$ create memif socket id 1 filename /tmp/gopacket-example // vpp$ create interface memif id 1 socket-id 1 slave secret secret no-zero-copy // vpp$ set int state memif1/1 up // vpp$ set int ip address memif1/1 192.168.1.2/24 // // To start the example, simply type: // root$ ./gopacket // // gopacket needs to be run as root so that it can access the socket // created by VPP. // // Normally, the memif interface is in the master mode. Pass CLI flag "--slave" // to create memif in the slave mode: // root$ ./gopacket --slave // // Don't forget to put the opposite memif into the master mode in that case. // // To verify the connection, run: // vpp$ ping 192.168.1.1 // 64 bytes from 192.168.1.1: icmp_seq=2 ttl=255 time=.6974 ms // 64 bytes from 192.168.1.1: icmp_seq=3 ttl=255 time=.6310 ms // 64 bytes from 192.168.1.1: icmp_seq=4 ttl=255 time=1.0350 ms // 64 bytes from 192.168.1.1: icmp_seq=5 ttl=255 time=.5359 ms // // Statistics: 5 sent, 4 received, 20% packet loss // vpp$ sh ip arp // Time IP4 Flags Ethernet Interface // 68.5648 192.168.1.1 D aa:aa:aa:aa:aa:aa memif0/1 // // Note: it is expected that the first ping is shown as lost. It was actually // converted to an ARP request. This is a VPP feature common to all interface // types. // // Stop the example with an interrupt signal. package main import ( "errors" "fmt" "io" "net" "os" "os/signal" "github.com/google/gopacket" "github.com/google/gopacket/layers" "git.fd.io/govpp.git/extras/libmemif" ) var ( // Used to signalize interrupt goroutines to stop stopCh chan struct{} // MAC address assigned to the memif interface. hwAddr net.HardwareAddr // IPAddress assigned to the memif interface. ipAddr net.IP // ErrUnhandledPacket is thrown and printed when an unexpected packet is received. ErrUnhandledPacket = errors.New("received an unhandled packet") ) // OnConnect is called when a memif connection gets established. func OnConnect(memif *libmemif.Memif) (err error) { // Use Memif.GetDetails to get the number of queues. details, err := memif.GetDetails() if err != nil { fmt.Printf("libmemif.GetDetails() error: %v\n", err) return } fmt.Printf("memif %s has been connected: %+v\n", memif.IfName, details) stopCh = make(chan struct{}) // Start a separate go routine for each RX queue. // (memif queue is a unit of parallelism for Rx/Tx). // Beware: the number of queues created may be lower than what was requested // in MemifConfiguration (the master makes the final decision). for _, queue := range details.RxQueues { ch, err := memif.GetQueueInterruptChan(queue.QueueID) if err != nil { fmt.Printf("libmemif.Memif.GetQueueInterruptChan() error %v\n", err) continue } go CreateInterruptCallback(memif.NewPacketHandle(queue.QueueID, 10), ch, OnInterrupt) } return } // OnDisconnect is called when a memif connection is lost. func OnDisconnect(memif *libmemif.Memif) (err error) { fmt.Printf("memif %s has been disconnected\n", memif.IfName) // Stop all packet producers and consumers. close(stopCh) return nil } // OnInterrupt is called when interrupted func OnInterrupt(handle *libmemif.MemifPacketHandle) { source := gopacket.NewPacketSource(handle, layers.LayerTypeEthernet) var responses []gopacket.Packet // Process ICMP pings for packet := range source.Packets() { fmt.Println("Received new packet:") fmt.Println(packet.Dump()) response, err := GeneratePacketResponse(packet) if err != nil { fmt.Printf("Failed to generate response: %v\n", err) continue } fmt.Println("Sending response:") fmt.Println(response.Dump()) responses = append(responses, response) } // Answer with ICMP pongs for i, response := range responses { err := handle.WritePacketData(response.Data()) switch err { case io.EOF: return case nil: fmt.Printf("Succesfully sent packet #%v %v\n", i, len(response.Data())) default: fmt.Printf("Got error while sending packet #%v %v\n", i, err) } } } // Creates user-friendly memif interrupt callback func CreateInterruptCallback(handle *libmemif.MemifPacketHandle, interruptCh <-chan struct{}, callback func(handle *libmemif.MemifPacketHandle)) { for { select { case <-interruptCh: callback(handle) case <-stopCh: handle.Close() return } } } // GeneratePacketResponse returns an appropriate answer to an ARP request // or an ICMP echo request. func GeneratePacketResponse(packet gopacket.Packet) (response gopacket.Packet, err error) { ethLayer := packet.Layer(layers.LayerTypeEthernet) eth, ok := ethLayer.(*layers.Ethernet) if !ok { fmt.Println("Missing ETH layer.") return nil, ErrUnhandledPacket } // Set up buffer and options for serialization. buf := gopacket.NewSerializeBuffer() opts := gopacket.SerializeOptions{ FixLengths: true, ComputeChecksums: true, } switch eth.EthernetType { case layers.EthernetTypeARP: // Handle ARP request. arpLayer := packet.Layer(layers.LayerTypeARP) arp, ok := arpLayer.(*layers.ARP) if !ok { fmt.Println("Missing ARP layer.") return nil, ErrUnhandledPacket } if arp.Operation != layers.ARPRequest { fmt.Println("Not ARP request.") return nil, ErrUnhandledPacket } fmt.Println("Received an ARP request.") // Build packet layers. ethResp := layers.Ethernet{ SrcMAC: hwAddr, DstMAC: eth.SrcMAC, EthernetType: layers.EthernetTypeARP, } arpResp := layers.ARP{ AddrType: layers.LinkTypeEthernet, Protocol: layers.EthernetTypeIPv4, HwAddressSize: 6, ProtAddressSize: 4, Operation: layers.ARPReply, SourceHwAddress: []byte(hwAddr), SourceProtAddress: []byte(ipAddr), DstHwAddress: arp.SourceHwAddress, DstProtAddress: arp.SourceProtAddress, } if err := gopacket.SerializeLayers(buf, opts, ðResp, &arpResp); err != nil { fmt.Println("SerializeLayers error: ", err) return nil, ErrUnhandledPacket } case layers.EthernetTypeIPv4: // Respond to ICMP request. ipLayer := packet.Layer(layers.LayerTypeIPv4) ipv4, ok := ipLayer.(*layers.IPv4) if !ok { fmt.Println("Missing IPv4 layer.") return nil, ErrUnhandledPacket } if ipv4.Protocol != layers.IPProtocolICMPv4 { fmt.Println("Not ICMPv4 protocol.") return nil, ErrUnhandledPacket } icmpLayer := packet.Layer(layers.LayerTypeICMPv4) icmp, ok := icmpLayer.(*layers.ICMPv4) if !ok { fmt.Println("Missing ICMPv4 layer.") return nil, ErrUnhandledPacket } if icmp.TypeCode.Type() != layers.ICMPv4TypeEchoRequest { fmt.Println("Not ICMPv4 echo request.") return nil, ErrUnhandledPacket } fmt.Println("Received an ICMPv4 echo request.") // Build packet layers. ethResp := layers.Ethernet{ SrcMAC: hwAddr, DstMAC: eth.SrcMAC, EthernetType: layers.EthernetTypeIPv4, } ipv4Resp := layers.IPv4{ Version: 4, IHL: 5, TOS: 0, Id: 0, Flags: 0, FragOffset: 0, TTL: 255, Protocol: layers.IPProtocolICMPv4, SrcIP: ipAddr, DstIP: ipv4.SrcIP, } icmpResp := layers.ICMPv4{ TypeCode: layers.CreateICMPv4TypeCode(layers.ICMPv4TypeEchoReply, 0), Id: icmp.Id, Seq: icmp.Seq, } if err := gopacket.SerializeLayers(buf, opts, ðResp, &ipv4Resp, &icmpResp, gopacket.Payload(icmp.Payload)); err != nil { fmt.Println("SerializeLayers error: ", err) return nil, ErrUnhandledPacket } default: return nil, ErrUnhandledPacket } return gopacket.NewPacket(buf.Bytes(), layers.LayerTypeEthernet, gopacket.Default), nil } func main() { fmt.Println("Starting 'gopacket' example...") var err error // Parse MAC address associated with memif interface hwAddr, err = net.ParseMAC("aa:aa:aa:aa:aa:aa") if err != nil { fmt.Printf("Failed to parse the MAC address: %v/n", err) return } // Parse IP address associated with memif interface ip := net.ParseIP("192.168.1.1") if ip != nil { ipAddr = ip.To4() } if ipAddr == nil { fmt.Println("Failed to parse the IP address") return } // If run with the "--slave" option, create memif in the slave mode. var isMaster = true var appSuffix string if len(os.Args) > 1 && (os.Args[1] == "--slave" || os.Args[1] == "-slave") { isMaster = false appSuffix = "-slave" } // Initialize libmemif first. appName := "gopacket" + appSuffix fmt.Println("Initializing libmemif as ", appName) err = libmemif.Init(appName) if err != nil { fmt.Printf("libmemif.Init() error: %v\n", err) return } // Schedule automatic cleanup. defer libmemif.Cleanup() // Prepare callbacks to use with the memif. // The same callbacks could be used with multiple memifs. // The first input argument (*libmemif.Memif) can be used to tell which // memif the callback was triggered for. memifCallbacks := &libmemif.MemifCallbacks{ OnConnect: OnConnect, OnDisconnect: OnDisconnect, } // Prepare memif1 configuration. memifConfig := &libmemif.MemifConfig{ MemifMeta: libmemif.MemifMeta{ IfName: "memif1", ConnID: 1, // ConnectionID is an identifier used to match opposite memifs. SocketFilename: "/tmp/gopacket-example", // Socket through which the opposite memifs will establish the connection. Secret: "secret", // Secret used to authenticate the memif connection. IsMaster: isMaster, Mode: libmemif.IfModeEthernet, }, MemifShmSpecs: libmemif.MemifShmSpecs{ NumRxQueues: 3, // NumQueues is the (configured!) number of queues for both Rx & Tx. NumTxQueues: 3, // The actual number agreed during connection establishment may be smaller! BufferSize: 2048, Log2RingSize: 10, }, } fmt.Printf("Callbacks: %+v\n", memifCallbacks) fmt.Printf("Config: %+v\n", memifConfig) // Create memif1 interface. memif, err := libmemif.CreateInterface(memifConfig, memifCallbacks) if err != nil { fmt.Printf("libmemif.CreateInterface() error: %v\n", err) return } // Schedule automatic cleanup of the interface. defer memif.Close() // Wait until an interrupt signal is received. sigChan := make(chan os.Signal, 1) signal.Notify(sigChan, os.Interrupt) <-sigChan }