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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ipv6
import (
"encoding/binary"
"fmt"
"net"
)
const (
Version = 6 // protocol version
HeaderLen = 40 // header length
)
// A Header represents an IPv6 base header.
type Header struct {
Version int // protocol version
TrafficClass int // traffic class
FlowLabel int // flow label
PayloadLen int // payload length
NextHeader int // next header
HopLimit int // hop limit
Src net.IP // source address
Dst net.IP // destination address
}
func (h *Header) String() string {
if h == nil {
return "<nil>"
}
return fmt.Sprintf("ver=%d tclass=%#x flowlbl=%#x payloadlen=%d nxthdr=%d hoplim=%d src=%v dst=%v", h.Version, h.TrafficClass, h.FlowLabel, h.PayloadLen, h.NextHeader, h.HopLimit, h.Src, h.Dst)
}
// ParseHeader parses b as an IPv6 base header.
func ParseHeader(b []byte) (*Header, error) {
if len(b) < HeaderLen {
return nil, errHeaderTooShort
}
h := &Header{
Version: int(b[0]) >> 4,
TrafficClass: int(b[0]&0x0f)<<4 | int(b[1])>>4,
FlowLabel: int(b[1]&0x0f)<<16 | int(b[2])<<8 | int(b[3]),
PayloadLen: int(binary.BigEndian.Uint16(b[4:6])),
NextHeader: int(b[6]),
HopLimit: int(b[7]),
}
h.Src = make(net.IP, net.IPv6len)
copy(h.Src, b[8:24])
h.Dst = make(net.IP, net.IPv6len)
copy(h.Dst, b[24:40])
return h, nil
}
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