112 lines
2.6 KiB
Go
112 lines
2.6 KiB
Go
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package nl
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import (
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"errors"
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"fmt"
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"net"
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)
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type IPv6SrHdr struct {
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nextHdr uint8
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hdrLen uint8
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routingType uint8
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segmentsLeft uint8
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firstSegment uint8
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flags uint8
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reserved uint16
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Segments []net.IP
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}
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func (s1 *IPv6SrHdr) Equal(s2 IPv6SrHdr) bool {
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if len(s1.Segments) != len(s2.Segments) {
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return false
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}
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for i := range s1.Segments {
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if s1.Segments[i].Equal(s2.Segments[i]) != true {
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return false
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}
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}
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return s1.nextHdr == s2.nextHdr &&
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s1.hdrLen == s2.hdrLen &&
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s1.routingType == s2.routingType &&
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s1.segmentsLeft == s2.segmentsLeft &&
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s1.firstSegment == s2.firstSegment &&
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s1.flags == s2.flags
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// reserved doesn't need to be identical.
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}
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// seg6 encap mode
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const (
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SEG6_IPTUN_MODE_INLINE = iota
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SEG6_IPTUN_MODE_ENCAP
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)
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// number of nested RTATTR
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// from include/uapi/linux/seg6_iptunnel.h
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const (
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SEG6_IPTUNNEL_UNSPEC = iota
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SEG6_IPTUNNEL_SRH
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__SEG6_IPTUNNEL_MAX
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)
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const (
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SEG6_IPTUNNEL_MAX = __SEG6_IPTUNNEL_MAX - 1
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)
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func EncodeSEG6Encap(mode int, segments []net.IP) ([]byte, error) {
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nsegs := len(segments) // nsegs: number of segments
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if nsegs == 0 {
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return nil, errors.New("EncodeSEG6Encap: No Segment in srh")
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}
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b := make([]byte, 12, 12+len(segments)*16)
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native := NativeEndian()
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native.PutUint32(b, uint32(mode))
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b[4] = 0 // srh.nextHdr (0 when calling netlink)
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b[5] = uint8(16 * nsegs >> 3) // srh.hdrLen (in 8-octets unit)
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b[6] = IPV6_SRCRT_TYPE_4 // srh.routingType (assigned by IANA)
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b[7] = uint8(nsegs - 1) // srh.segmentsLeft
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b[8] = uint8(nsegs - 1) // srh.firstSegment
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b[9] = 0 // srh.flags (SR6_FLAG1_HMAC for srh_hmac)
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// srh.reserved: Defined as "Tag" in draft-ietf-6man-segment-routing-header-07
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native.PutUint16(b[10:], 0) // srh.reserved
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for _, netIP := range segments {
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b = append(b, netIP...) // srh.Segments
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}
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return b, nil
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}
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func DecodeSEG6Encap(buf []byte) (int, []net.IP, error) {
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native := NativeEndian()
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mode := int(native.Uint32(buf))
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srh := IPv6SrHdr{
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nextHdr: buf[4],
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hdrLen: buf[5],
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routingType: buf[6],
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segmentsLeft: buf[7],
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firstSegment: buf[8],
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flags: buf[9],
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reserved: native.Uint16(buf[10:12]),
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}
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buf = buf[12:]
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if len(buf)%16 != 0 {
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err := fmt.Errorf("DecodeSEG6Encap: error parsing Segment List (buf len: %d)\n", len(buf))
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return mode, nil, err
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}
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for len(buf) > 0 {
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srh.Segments = append(srh.Segments, net.IP(buf[:16]))
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buf = buf[16:]
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}
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return mode, srh.Segments, nil
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}
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// Helper functions
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func SEG6EncapModeString(mode int) string {
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switch mode {
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case SEG6_IPTUN_MODE_INLINE:
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return "inline"
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case SEG6_IPTUN_MODE_ENCAP:
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return "encap"
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}
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return "unknown"
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}
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