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@ -7,6 +7,7 @@ import (
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"fmt"
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"fmt"
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"github.com/google/gopacket"
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"github.com/google/gopacket"
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"github.com/google/gopacket/layers"
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"github.com/google/gopacket/layers"
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dhcp "github.com/krolaw/dhcp4"
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log "github.com/sirupsen/logrus"
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log "github.com/sirupsen/logrus"
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"io"
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"io"
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"net"
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"net"
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@ -109,10 +110,17 @@ func pipeForward(prefix string) {
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log.Debug("Start packet")
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log.Debug("Start packet")
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filterMAC(prefix, &frame.DstMAC, &frame.SrcMAC, frame.LayerType())
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filterMAC(prefix, &frame.DstMAC, &frame.SrcMAC, frame.LayerType())
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// Handle IPv6 packet
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// Handle IPv4 packet
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if ipv4layer := packet.Layer(layers.LayerTypeIPv4); ipv4layer != nil {
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if ipv4layer := packet.Layer(layers.LayerTypeIPv4); ipv4layer != nil {
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ipv4Packet, _ := ipv4layer.(*layers.IPv4)
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ipv4Packet, _ := ipv4layer.(*layers.IPv4)
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log.Debug("IP Protocol ", ipv4Packet.Protocol)
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log.Debug("IP Protocol ", ipv4Packet.Protocol)
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// Handle DHCPv4 packet (based on IPv4)
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if dhcpLayer := packet.Layer(layers.LayerTypeDHCPv4); dhcpLayer != nil && !Passthrough {
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handleDHCP(dhcpLayer.LayerContents(), frame.DstMAC, prefix)
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continue
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}
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filterIP(prefix, &ipv4Packet.DstIP, &ipv4Packet.SrcIP, ipv4Packet.LayerType())
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filterIP(prefix, &ipv4Packet.DstIP, &ipv4Packet.SrcIP, ipv4Packet.LayerType())
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// Handle ICMP packet (based on IPv4)
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// Handle ICMP packet (based on IPv4)
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@ -121,13 +129,6 @@ func pipeForward(prefix string) {
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log.Debug(prefix, "ICMP Type ", icmpPacket.TypeCode)
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log.Debug(prefix, "ICMP Type ", icmpPacket.TypeCode)
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}
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}
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// Handle DHCP packet (based on IPv4) - drop for now
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if dhcpLayer := packet.Layer(layers.LayerTypeDHCPv4); dhcpLayer != nil && !Passthrough {
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//dhcpPacket, _ := dhcpLayer.(*layers.DHCPv4)
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log.Info(prefix, "DHCP packet dropped")
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continue
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}
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// Handle TCP packet
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// Handle TCP packet
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if tcpLayer := packet.Layer(layers.LayerTypeTCP); tcpLayer != nil {
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if tcpLayer := packet.Layer(layers.LayerTypeTCP); tcpLayer != nil {
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tcpPacket, _ := tcpLayer.(*layers.TCP)
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tcpPacket, _ := tcpLayer.(*layers.TCP)
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@ -175,7 +176,7 @@ func pipeForward(prefix string) {
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if isInteresting {
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if isInteresting {
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util.WriteBinary(fmt.Sprintf("/tmp/pck_%di.dat", time.Now().Unix()), frameBytes)
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util.WriteBinary(fmt.Sprintf("/tmp/pck_%di.dat", time.Now().Unix()), frameBytes)
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util.WriteBinary(fmt.Sprintf("/tmp/pck_%do.dat", time.Now().Unix()), newFrameBytes)
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util.WriteBinary(fmt.Sprintf("/tmp/pck_%do.dat", time.Now().Unix()), newFrameBytes)
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//util.WritePcap("xyz.pcap", packet.Data(), packet.Metadata().CaptureInfo)
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//util.WritePcapNg("xyz.pcap", packet.Data(), packet.Metadata().CaptureInfo)
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}
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}
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// Forward modified frame to other plug
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// Forward modified frame to other plug
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@ -210,6 +211,9 @@ func filterIP(prefix string, dst interface{}, src interface{}, context gopacket.
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return
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return
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} else if prefix == cmd.Out {
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} else if prefix == cmd.Out {
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if isIp {
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if isIp {
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if!ip.IsGlobalUnicast() {
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return
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}
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OldIP = *ip
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OldIP = *ip
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} else if isBs {
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} else if isBs {
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OldIP = *bs
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OldIP = *bs
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@ -267,4 +271,107 @@ func filterMAC(prefix string, dst interface{}, src interface{}, context gopacket
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*bs = newVal
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*bs = newVal
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log.Debugf("%s%s %s MAC %s changed to %s", prefix, context, which, condVal, newVal)
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log.Debugf("%s%s %s MAC %s changed to %s", prefix, context, which, condVal, newVal)
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}
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}
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}
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func handleDHCP(content []byte, srcMAC net.HardwareAddr, prefix string) {
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req := dhcp.Packet(content)
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if req.HLen() > 16 { // Invalid size
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log.Error(prefix, "Invalid DHCP size")
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return
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}
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options := req.ParseOptions()
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var reqType dhcp.MessageType
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if t := options[dhcp.OptionDHCPMessageType]; len(t) != 1 {
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log.Error(prefix, "Invalid DHCP message type")
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return
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} else {
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reqType = dhcp.MessageType(t[0])
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if reqType < dhcp.Discover || reqType > dhcp.Inform {
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log.Error(prefix, "Invalid DHCP message type: ", reqType)
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return
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}
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}
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log.Debug(prefix, "DHCP message registered: ", reqType)
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if prefix == cmd.Out {
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switch reqType {
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case dhcp.Discover:
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if OldIP == nil {
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log.Fatal(prefix, "DHCPDISCOVER but not previous address is known")
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}
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sendDHCPReply(req, dhcp.Offer, OldIP, options, srcMAC)
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case dhcp.Request:
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reqIP := net.IP(options[dhcp.OptionRequestedIPAddress])
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if reqIP == nil {
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reqIP = req.CIAddr()
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}
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if len(reqIP) != 4 || reqIP.Equal(net.IPv4zero) {
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log.Error(prefix, "Invalid IP requested in DHCP: ", reqIP)
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return
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}
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sendDHCPReply(req, dhcp.ACK, reqIP, options, srcMAC)
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default:
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return
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}
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} else {
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// TODO: talk to dhcp server
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}
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}
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// sendDHCPReply creates a response dhcp packet and sends it
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func sendDHCPReply(req dhcp.Packet, mt dhcp.MessageType, lease net.IP, reqOpt dhcp.Options, dstMAC net.HardwareAddr) {
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log.Info("Sending DHCP response: ", mt, lease)
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// Getting the options
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serverIP := []byte{10, 0, 0, 1} // TODO: serverIP
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serverMAC := util.GenerateMac("") // TODO: server MAC
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opt := dhcp.Options{
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dhcp.OptionSubnetMask: []byte{255, 255, 255, 0}, // TODO: subnet mask
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dhcp.OptionRouter: serverIP, // TODO: Presuming Server is also your router
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dhcp.OptionDomainNameServer: serverIP, // TODO: Presuming Server is also your DNS server
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}.SelectOrderOrAll(reqOpt[dhcp.OptionParameterRequestList])
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// Creating the full packet layer by layer
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dhcplayer := dhcp.ReplyPacket(req, mt, serverIP, lease, 24 * time.Hour, opt)
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buf := gopacket.NewSerializeBuffer()
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opts := gopacket.SerializeOptions{
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ComputeChecksums: true,
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FixLengths: true,
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}
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ipv4 := layers.IPv4{
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Version: 4,
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TTL: 64,
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Protocol: layers.IPProtocolUDP,
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SrcIP: serverIP,
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DstIP: lease,
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}
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udp := layers.UDP{
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SrcPort: 67,
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DstPort: 68,
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}
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udp.SetNetworkLayerForChecksum(&ipv4)
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err := gopacket.SerializeLayers(buf, opts,
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&layers.Ethernet{
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SrcMAC: serverMAC,
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DstMAC: dstMAC,
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EthernetType: layers.EthernetTypeIPv4,
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},
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&ipv4,
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&udp,
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gopacket.Payload(dhcplayer))
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if err != nil {
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return
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}
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packetData := buf.Bytes()
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// Sending layer through VM's pipe
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packetLength := make([]byte, 2)
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binary.BigEndian.PutUint16(packetLength, uint16(len(packetData)))
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util.WriteBinary(fmt.Sprintf("/tmp/dhcp_%d.dat", time.Now().Unix()), packetData)
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util.WritePcap(fmt.Sprintf("/tmp/dhcp_%d.pcap", time.Now().Unix()), packetData)
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util.WritePcap(fmt.Sprintf("/tmp/dhcp_%d2.pcap", time.Now().Unix()), packetData[36:])
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VmWriter.Write(packetLength)
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VmWriter.Write(packetData)
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}
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}
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