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|
package nl
import (
"errors"
"fmt"
"net"
)
type IPv6SrHdr struct {
nextHdr uint8
hdrLen uint8
routingType uint8
segmentsLeft uint8
firstSegment uint8
flags uint8
reserved uint16
Segments []net.IP
}
func (s1 *IPv6SrHdr) Equal(s2 IPv6SrHdr) bool {
if len(s1.Segments) != len(s2.Segments) {
return false
}
for i := range s1.Segments {
if !s1.Segments[i].Equal(s2.Segments[i]) {
return false
}
}
return s1.nextHdr == s2.nextHdr &&
s1.hdrLen == s2.hdrLen &&
s1.routingType == s2.routingType &&
s1.segmentsLeft == s2.segmentsLeft &&
s1.firstSegment == s2.firstSegment &&
s1.flags == s2.flags
// reserved doesn't need to be identical.
}
// seg6 encap mode
const (
SEG6_IPTUN_MODE_INLINE = iota
SEG6_IPTUN_MODE_ENCAP
)
// number of nested RTATTR
// from include/uapi/linux/seg6_iptunnel.h
const (
SEG6_IPTUNNEL_UNSPEC = iota
SEG6_IPTUNNEL_SRH
__SEG6_IPTUNNEL_MAX
)
const (
SEG6_IPTUNNEL_MAX = __SEG6_IPTUNNEL_MAX - 1
)
func EncodeSEG6Encap(mode int, segments []net.IP) ([]byte, error) {
nsegs := len(segments) // nsegs: number of segments
if nsegs == 0 {
return nil, errors.New("EncodeSEG6Encap: No Segment in srh")
}
b := make([]byte, 12, 12+len(segments)*16)
native := NativeEndian()
native.PutUint32(b, uint32(mode))
b[4] = 0 // srh.nextHdr (0 when calling netlink)
b[5] = uint8(16 * nsegs >> 3) // srh.hdrLen (in 8-octets unit)
b[6] = IPV6_SRCRT_TYPE_4 // srh.routingType (assigned by IANA)
b[7] = uint8(nsegs - 1) // srh.segmentsLeft
b[8] = uint8(nsegs - 1) // srh.firstSegment
b[9] = 0 // srh.flags (SR6_FLAG1_HMAC for srh_hmac)
// srh.reserved: Defined as "Tag" in draft-ietf-6man-segment-routing-header-07
native.PutUint16(b[10:], 0) // srh.reserved
for _, netIP := range segments {
b = append(b, netIP...) // srh.Segments
}
return b, nil
}
func DecodeSEG6Encap(buf []byte) (int, []net.IP, error) {
native := NativeEndian()
mode := int(native.Uint32(buf))
srh := IPv6SrHdr{
nextHdr: buf[4],
hdrLen: buf[5],
routingType: buf[6],
segmentsLeft: buf[7],
firstSegment: buf[8],
flags: buf[9],
reserved: native.Uint16(buf[10:12]),
}
buf = buf[12:]
if len(buf)%16 != 0 {
err := fmt.Errorf("DecodeSEG6Encap: error parsing Segment List (buf len: %d)", len(buf))
return mode, nil, err
}
for len(buf) > 0 {
srh.Segments = append(srh.Segments, net.IP(buf[:16]))
buf = buf[16:]
}
return mode, srh.Segments, nil
}
func DecodeSEG6Srh(buf []byte) ([]net.IP, error) {
native := NativeEndian()
srh := IPv6SrHdr{
nextHdr: buf[0],
hdrLen: buf[1],
routingType: buf[2],
segmentsLeft: buf[3],
firstSegment: buf[4],
flags: buf[5],
reserved: native.Uint16(buf[6:8]),
}
buf = buf[8:]
if len(buf)%16 != 0 {
err := fmt.Errorf("DecodeSEG6Srh: error parsing Segment List (buf len: %d)", len(buf))
return nil, err
}
for len(buf) > 0 {
srh.Segments = append(srh.Segments, net.IP(buf[:16]))
buf = buf[16:]
}
return srh.Segments, nil
}
func EncodeSEG6Srh(segments []net.IP) ([]byte, error) {
nsegs := len(segments) // nsegs: number of segments
if nsegs == 0 {
return nil, errors.New("EncodeSEG6Srh: No Segments")
}
b := make([]byte, 8, 8+len(segments)*16)
native := NativeEndian()
b[0] = 0 // srh.nextHdr (0 when calling netlink)
b[1] = uint8(16 * nsegs >> 3) // srh.hdrLen (in 8-octets unit)
b[2] = IPV6_SRCRT_TYPE_4 // srh.routingType (assigned by IANA)
b[3] = uint8(nsegs - 1) // srh.segmentsLeft
b[4] = uint8(nsegs - 1) // srh.firstSegment
b[5] = 0 // srh.flags (SR6_FLAG1_HMAC for srh_hmac)
// srh.reserved: Defined as "Tag" in draft-ietf-6man-segment-routing-header-07
native.PutUint16(b[6:], 0) // srh.reserved
for _, netIP := range segments {
b = append(b, netIP...) // srh.Segments
}
return b, nil
}
// Helper functions
func SEG6EncapModeString(mode int) string {
switch mode {
case SEG6_IPTUN_MODE_INLINE:
return "inline"
case SEG6_IPTUN_MODE_ENCAP:
return "encap"
}
return "unknown"
}
|
