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