add packet capture method
This commit is contained in:
parent
f45a5665cf
commit
98bc2c21ba
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@ -0,0 +1,90 @@
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package capture
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import (
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"fmt"
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"git.freifunk-franken.de/jkimmel/abbel/packet"
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"github.com/google/gopacket"
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"github.com/google/gopacket/afpacket"
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"github.com/google/gopacket/layers"
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"golang.org/x/net/bpf"
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"inet.af/netaddr"
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)
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var (
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// tcpdump -y RAW -dd ip6 and udp dst port 6696
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babelBPFRAW = []bpf.RawInstruction{
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{0x30, 0, 0, 0x00000000},
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{0x54, 0, 0, 0x000000f0},
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{0x15, 0, 5, 0x00000060},
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{0x30, 0, 0, 0x00000006},
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{0x15, 0, 3, 0x00000011},
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{0x28, 0, 0, 0x0000002a},
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{0x15, 0, 1, 0x00001a28},
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{0x6, 0, 0, 0x00040000},
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{0x6, 0, 0, 0x00000000},
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}
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)
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type Handle struct {
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tp *afpacket.TPacket
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}
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func FromInterface(iface string) (Handle, error) {
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var h Handle
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var err error
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if iface != "any" {
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h.tp, err = afpacket.NewTPacket(
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afpacket.SocketDgram,
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afpacket.OptInterface(iface),
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)
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} else {
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h.tp, err = afpacket.NewTPacket(
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afpacket.SocketDgram,
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)
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}
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if err != nil {
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fmt.Println("here")
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return Handle{}, err
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}
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err = h.tp.SetBPF(babelBPFRAW)
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if err != nil {
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return Handle{}, err
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}
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return h, nil
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}
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func (h Handle) Close() error {
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h.tp.Close()
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return nil
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}
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func (h Handle) ReadFrom(b []byte) (body []byte, src netaddr.IP, ifindex int, err error) {
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data, ci, err := h.tp.ZeroCopyReadPacketData()
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if err != nil {
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return nil, netaddr.IP{}, 0, err
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}
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pckt := gopacket.NewPacket(data, layers.LayerTypeIPv6, gopacket.NoCopy)
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ip6, ok := pckt.NetworkLayer().(*layers.IPv6)
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if !ok {
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return nil, netaddr.IP{}, 0, fmt.Errorf("Expected IPv6 layer, got %v", pckt.NetworkLayer())
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}
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src, ok = netaddr.FromStdIP(ip6.SrcIP)
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if !ok {
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return nil, netaddr.IP{}, 0, fmt.Errorf("Error parsing packet src address %q", ip6.SrcIP)
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}
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payload := pckt.ApplicationLayer().Payload()
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copy(b, payload)
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b, err = packet.Validate(b[:len(payload)])
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if err != nil {
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return nil, netaddr.IP{}, 0, err
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}
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return b, src, ci.InterfaceIndex, nil
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}
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1
go.mod
1
go.mod
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@ -3,6 +3,7 @@ module git.freifunk-franken.de/jkimmel/abbel
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go 1.0
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require (
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github.com/google/gopacket v1.1.19
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golang.org/x/net v0.0.0-20210226172049-e18ecbb05110
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inet.af/netaddr v0.0.0-20211027220019-c74959edd3b6
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)
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5
go.sum
5
go.sum
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@ -1,4 +1,6 @@
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github.com/dvyukov/go-fuzz v0.0.0-20210103155950-6a8e9d1f2415/go.mod h1:11Gm+ccJnvAhCNLlf5+cS9KjtbaD5I5zaZpFMsTHWTw=
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github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
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github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
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github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
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go4.org/intern v0.0.0-20211027215823-ae77deb06f29 h1:UXLjNohABv4S58tHmeuIZDO6e3mHpW2Dx33gaNt03LE=
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go4.org/intern v0.0.0-20211027215823-ae77deb06f29/go.mod h1:cS2ma+47FKrLPdXFpr7CuxiTW3eyJbWew4qx0qtQWDA=
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@ -7,6 +9,8 @@ go4.org/unsafe/assume-no-moving-gc v0.0.0-20211027215541-db492cf91b37/go.mod h1:
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golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
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golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
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golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
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golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
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golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
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golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
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golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
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golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
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@ -26,6 +30,7 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
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golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
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golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
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golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
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golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
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golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
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golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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51
main.go
51
main.go
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@ -4,14 +4,17 @@ import (
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"fmt"
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"log"
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"git.freifunk-franken.de/jkimmel/abbel/capture"
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"git.freifunk-franken.de/jkimmel/abbel/packet"
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"git.freifunk-franken.de/jkimmel/abbel/tlv"
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"inet.af/netaddr"
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)
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type options struct {
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Group string
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Port uint16
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Ifs []string
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UseCapture bool
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}
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func parseOpts() (options, error) {
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@ -22,13 +25,36 @@ func parseOpts() (options, error) {
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Group: "ff02:0:0:0:0:0:1:6",
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Port: 6696,
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Ifs: []string{"babel"},
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UseCapture: false,
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}
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return opt, err
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}
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type updatesKey struct {
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prefix netaddr.IPPrefix
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routerID tlv.RouterID
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nexthop netaddr.IP
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}
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var (
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updates = map[updatesKey]tlv.Update{}
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)
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type BabelPacketConn interface {
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ReadFrom(b []byte) (body []byte, src netaddr.IP, ifindex int, err error)
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Close() error
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}
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func run(opt options) error {
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conn, err := packet.Listen(opt.Group, opt.Port, opt.Ifs...)
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var err error
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var conn BabelPacketConn
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if opt.UseCapture {
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conn, err = capture.FromInterface(opt.Ifs[0])
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} else {
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conn, err = packet.Listen(opt.Group, opt.Port, opt.Ifs...)
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}
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if err != nil {
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return err
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}
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buf := [4096]byte{}
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var s tlv.PacketDecoder
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for {
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b, src, rcm, err := conn.ReadFrom(buf[:])
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b, src, ifindex, err := conn.ReadFrom(buf[:])
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if err != nil {
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fmt.Println("Skipping packet:", err)
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continue
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}
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fmt.Print("\x1B[1m")
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fmt.Printf("Packet size %4d %s", len(b), rcm)
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fmt.Printf("Packet size %4d from %s", len(b), src)
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fmt.Println("\x1B[0m")
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s.Reset(b, src, rcm.IfIndex)
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s.Reset(b, src, ifindex)
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for s.Scan() {
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switch t := s.TLV().(type) {
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case tlv.NextHop:
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fmt.Printf("%12s %s\n", t.T(), t.Address)
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//fmt.Printf("%12s %s\n", t.T(), t.Address)
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case tlv.Hello:
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fmt.Printf("% 12s %+v\n", t.T(), t)
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case tlv.Update:
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if err != nil {
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fmt.Println(t, t.Prefix, err)
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} else {
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key := updatesKey{t.Prefix, t.RouterID, t.NextHop}
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tmetric := t.Metric
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diff := int(tmetric) - int(updates[key].Metric)
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updates[key] = t
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if diff == 0 && tmetric != 0xFFFF {
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break
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}
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if t.Metric == 0xFFFF {
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fmt.Print("\x1B[31m")
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} else {
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fmt.Print("\x1B[36m")
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}
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fmt.Printf("% 12s %-43s%s\x1B[0m\n", t.T(), t.Prefix, t.FormatHeader())
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}
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fmt.Printf("% 12s %-43s%+d %s\x1B[0m\n", t.T(), t.Prefix, diff, t.FormatHeader())
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case tlv.RouterID:
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fmt.Printf("%12s %s\n", t.T(), t)
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//fmt.Printf("%12s %s\n", t.T(), t)
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case tlv.RouteRequest:
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fmt.Printf("%12s %s\n", t.T(), t.Prefix)
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case tlv.Raw:
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@ -63,16 +63,11 @@ func (c Conn) JoinGroup(ifname string, addr string) error {
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return c.v6pc.JoinGroup(ifi, &net.UDPAddr{IP: ip.IPAddr().IP})
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}
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func (c Conn) ReadFrom(b []byte) (body []byte, src netaddr.IP, rcm *ipv6.ControlMessage, err error) {
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var n int
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n, rcm, _, err = c.v6pc.ReadFrom(b)
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if err != nil {
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return nil, netaddr.IP{}, nil, err
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}
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func Validate(b []byte) ([]byte, error) {
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n := len(b)
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b = b[:n]
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if len(b) < BabelPacketHeaderSize {
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return nil, netaddr.IP{}, nil, fmt.Errorf("Packet too short: %d", len(b))
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if n < BabelPacketHeaderSize {
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return nil, fmt.Errorf("Packet too short: %d", len(b))
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}
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magic := b[0]
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@ -81,22 +76,36 @@ func (c Conn) ReadFrom(b []byte) (body []byte, src netaddr.IP, rcm *ipv6.Control
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b = b[4:]
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if magic != BabelMagic {
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return nil, netaddr.IP{}, nil, fmt.Errorf("Invalid magic number %d", magic)
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return nil, fmt.Errorf("Invalid magic number %d", magic)
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}
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if version != BabelVersion {
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return nil, netaddr.IP{}, nil, fmt.Errorf("Unsupported version number %d", version)
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return nil, fmt.Errorf("Unsupported version number %d", version)
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}
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if int(length) > len(b) {
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return nil, netaddr.IP{}, nil, fmt.Errorf("Invalid length for packet of size %d: %d", n, length)
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return nil, fmt.Errorf("Invalid length for packet of size %d: %d", n, length)
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}
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return b, nil
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}
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func (c Conn) ReadFrom(b []byte) (body []byte, src netaddr.IP, ifindex int, err error) {
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n, rcm, _, err := c.v6pc.ReadFrom(b)
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if err != nil {
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return nil, netaddr.IP{}, 0, err
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}
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b, err = Validate(b[:n])
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if err != nil {
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return nil, netaddr.IP{}, 0, err
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}
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var ok bool
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src, ok = netaddr.FromStdIPRaw(rcm.Src)
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if !ok {
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return nil, netaddr.IP{}, nil, fmt.Errorf("Invalid src address %q", rcm.Src)
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return nil, netaddr.IP{}, 0, fmt.Errorf("Invalid src address %q", rcm.Src)
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}
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return b, src, rcm, err
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return b, src, rcm.IfIndex, err
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}
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