323 lines
7.7 KiB
Go
323 lines
7.7 KiB
Go
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// Copyright 2015 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 icmp
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import (
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"encoding/binary"
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"net"
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"strings"
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"golang.org/x/net/internal/iana"
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)
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const (
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classInterfaceInfo = 2
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)
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const (
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attrMTU = 1 << iota
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attrName
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attrIPAddr
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attrIfIndex
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)
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// An InterfaceInfo represents interface and next-hop identification.
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type InterfaceInfo struct {
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Class int // extension object class number
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Type int // extension object sub-type
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Interface *net.Interface
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Addr *net.IPAddr
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}
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func (ifi *InterfaceInfo) nameLen() int {
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if len(ifi.Interface.Name) > 63 {
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return 64
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}
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l := 1 + len(ifi.Interface.Name)
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return (l + 3) &^ 3
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}
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func (ifi *InterfaceInfo) attrsAndLen(proto int) (attrs, l int) {
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l = 4
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if ifi.Interface != nil && ifi.Interface.Index > 0 {
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attrs |= attrIfIndex
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l += 4
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if len(ifi.Interface.Name) > 0 {
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attrs |= attrName
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l += ifi.nameLen()
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}
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if ifi.Interface.MTU > 0 {
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attrs |= attrMTU
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l += 4
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}
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}
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if ifi.Addr != nil {
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switch proto {
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case iana.ProtocolICMP:
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if ifi.Addr.IP.To4() != nil {
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attrs |= attrIPAddr
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l += 4 + net.IPv4len
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}
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case iana.ProtocolIPv6ICMP:
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if ifi.Addr.IP.To16() != nil && ifi.Addr.IP.To4() == nil {
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attrs |= attrIPAddr
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l += 4 + net.IPv6len
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}
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}
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}
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return
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}
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// Len implements the Len method of Extension interface.
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func (ifi *InterfaceInfo) Len(proto int) int {
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_, l := ifi.attrsAndLen(proto)
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return l
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}
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// Marshal implements the Marshal method of Extension interface.
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func (ifi *InterfaceInfo) Marshal(proto int) ([]byte, error) {
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attrs, l := ifi.attrsAndLen(proto)
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b := make([]byte, l)
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if err := ifi.marshal(proto, b, attrs, l); err != nil {
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return nil, err
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}
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return b, nil
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}
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func (ifi *InterfaceInfo) marshal(proto int, b []byte, attrs, l int) error {
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binary.BigEndian.PutUint16(b[:2], uint16(l))
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b[2], b[3] = classInterfaceInfo, byte(ifi.Type)
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for b = b[4:]; len(b) > 0 && attrs != 0; {
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switch {
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case attrs&attrIfIndex != 0:
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b = ifi.marshalIfIndex(proto, b)
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attrs &^= attrIfIndex
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case attrs&attrIPAddr != 0:
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b = ifi.marshalIPAddr(proto, b)
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attrs &^= attrIPAddr
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case attrs&attrName != 0:
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b = ifi.marshalName(proto, b)
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attrs &^= attrName
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case attrs&attrMTU != 0:
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b = ifi.marshalMTU(proto, b)
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attrs &^= attrMTU
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}
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}
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return nil
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}
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func (ifi *InterfaceInfo) marshalIfIndex(proto int, b []byte) []byte {
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binary.BigEndian.PutUint32(b[:4], uint32(ifi.Interface.Index))
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return b[4:]
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}
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func (ifi *InterfaceInfo) parseIfIndex(b []byte) ([]byte, error) {
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if len(b) < 4 {
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return nil, errMessageTooShort
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}
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ifi.Interface.Index = int(binary.BigEndian.Uint32(b[:4]))
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return b[4:], nil
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}
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func (ifi *InterfaceInfo) marshalIPAddr(proto int, b []byte) []byte {
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switch proto {
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case iana.ProtocolICMP:
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binary.BigEndian.PutUint16(b[:2], uint16(iana.AddrFamilyIPv4))
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copy(b[4:4+net.IPv4len], ifi.Addr.IP.To4())
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b = b[4+net.IPv4len:]
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case iana.ProtocolIPv6ICMP:
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binary.BigEndian.PutUint16(b[:2], uint16(iana.AddrFamilyIPv6))
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copy(b[4:4+net.IPv6len], ifi.Addr.IP.To16())
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b = b[4+net.IPv6len:]
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}
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return b
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}
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func (ifi *InterfaceInfo) parseIPAddr(b []byte) ([]byte, error) {
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if len(b) < 4 {
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return nil, errMessageTooShort
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}
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afi := int(binary.BigEndian.Uint16(b[:2]))
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b = b[4:]
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switch afi {
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case iana.AddrFamilyIPv4:
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if len(b) < net.IPv4len {
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return nil, errMessageTooShort
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}
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ifi.Addr.IP = make(net.IP, net.IPv4len)
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copy(ifi.Addr.IP, b[:net.IPv4len])
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b = b[net.IPv4len:]
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case iana.AddrFamilyIPv6:
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if len(b) < net.IPv6len {
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return nil, errMessageTooShort
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}
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ifi.Addr.IP = make(net.IP, net.IPv6len)
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copy(ifi.Addr.IP, b[:net.IPv6len])
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b = b[net.IPv6len:]
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}
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return b, nil
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}
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func (ifi *InterfaceInfo) marshalName(proto int, b []byte) []byte {
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l := byte(ifi.nameLen())
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b[0] = l
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copy(b[1:], []byte(ifi.Interface.Name))
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return b[l:]
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}
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func (ifi *InterfaceInfo) parseName(b []byte) ([]byte, error) {
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if 4 > len(b) || len(b) < int(b[0]) {
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return nil, errMessageTooShort
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}
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l := int(b[0])
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if l%4 != 0 || 4 > l || l > 64 {
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return nil, errInvalidExtension
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}
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var name [63]byte
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copy(name[:], b[1:l])
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ifi.Interface.Name = strings.Trim(string(name[:]), "\000")
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return b[l:], nil
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}
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func (ifi *InterfaceInfo) marshalMTU(proto int, b []byte) []byte {
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binary.BigEndian.PutUint32(b[:4], uint32(ifi.Interface.MTU))
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return b[4:]
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}
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func (ifi *InterfaceInfo) parseMTU(b []byte) ([]byte, error) {
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if len(b) < 4 {
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return nil, errMessageTooShort
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}
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ifi.Interface.MTU = int(binary.BigEndian.Uint32(b[:4]))
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return b[4:], nil
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}
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func parseInterfaceInfo(b []byte) (Extension, error) {
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ifi := &InterfaceInfo{
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Class: int(b[2]),
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Type: int(b[3]),
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}
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if ifi.Type&(attrIfIndex|attrName|attrMTU) != 0 {
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ifi.Interface = &net.Interface{}
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}
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if ifi.Type&attrIPAddr != 0 {
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ifi.Addr = &net.IPAddr{}
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}
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attrs := ifi.Type & (attrIfIndex | attrIPAddr | attrName | attrMTU)
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for b = b[4:]; len(b) > 0 && attrs != 0; {
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var err error
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switch {
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case attrs&attrIfIndex != 0:
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b, err = ifi.parseIfIndex(b)
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attrs &^= attrIfIndex
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case attrs&attrIPAddr != 0:
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b, err = ifi.parseIPAddr(b)
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attrs &^= attrIPAddr
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case attrs&attrName != 0:
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b, err = ifi.parseName(b)
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attrs &^= attrName
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case attrs&attrMTU != 0:
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b, err = ifi.parseMTU(b)
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attrs &^= attrMTU
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}
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if err != nil {
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return nil, err
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}
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}
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if ifi.Interface != nil && ifi.Interface.Name != "" && ifi.Addr != nil && ifi.Addr.IP.To16() != nil && ifi.Addr.IP.To4() == nil {
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ifi.Addr.Zone = ifi.Interface.Name
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}
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return ifi, nil
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}
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const (
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classInterfaceIdent = 3
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typeInterfaceByName = 1
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typeInterfaceByIndex = 2
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typeInterfaceByAddress = 3
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)
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// An InterfaceIdent represents interface identification.
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type InterfaceIdent struct {
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Class int // extension object class number
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Type int // extension object sub-type
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Name string // interface name
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Index int // interface index
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AFI int // address family identifier; see address family numbers in IANA registry
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Addr []byte // address
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}
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// Len implements the Len method of Extension interface.
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func (ifi *InterfaceIdent) Len(_ int) int {
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switch ifi.Type {
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case typeInterfaceByName:
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l := len(ifi.Name)
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if l > 255 {
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l = 255
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}
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return 4 + (l+3)&^3
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case typeInterfaceByIndex:
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return 4 + 4
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case typeInterfaceByAddress:
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return 4 + 4 + (len(ifi.Addr)+3)&^3
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default:
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return 4
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}
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}
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// Marshal implements the Marshal method of Extension interface.
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func (ifi *InterfaceIdent) Marshal(proto int) ([]byte, error) {
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b := make([]byte, ifi.Len(proto))
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if err := ifi.marshal(proto, b); err != nil {
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return nil, err
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}
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return b, nil
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}
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func (ifi *InterfaceIdent) marshal(proto int, b []byte) error {
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l := ifi.Len(proto)
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binary.BigEndian.PutUint16(b[:2], uint16(l))
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b[2], b[3] = classInterfaceIdent, byte(ifi.Type)
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switch ifi.Type {
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case typeInterfaceByName:
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copy(b[4:], ifi.Name)
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case typeInterfaceByIndex:
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binary.BigEndian.PutUint32(b[4:4+4], uint32(ifi.Index))
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case typeInterfaceByAddress:
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binary.BigEndian.PutUint16(b[4:4+2], uint16(ifi.AFI))
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b[4+2] = byte(len(ifi.Addr))
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copy(b[4+4:], ifi.Addr)
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}
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return nil
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}
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func parseInterfaceIdent(b []byte) (Extension, error) {
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ifi := &InterfaceIdent{
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Class: int(b[2]),
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Type: int(b[3]),
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}
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switch ifi.Type {
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case typeInterfaceByName:
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ifi.Name = strings.Trim(string(b[4:]), "\x00")
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case typeInterfaceByIndex:
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if len(b[4:]) < 4 {
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return nil, errInvalidExtension
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}
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ifi.Index = int(binary.BigEndian.Uint32(b[4 : 4+4]))
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case typeInterfaceByAddress:
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if len(b[4:]) < 4 {
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return nil, errInvalidExtension
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}
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ifi.AFI = int(binary.BigEndian.Uint16(b[4 : 4+2]))
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l := int(b[4+2])
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if len(b[4+4:]) < l {
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return nil, errInvalidExtension
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}
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ifi.Addr = make([]byte, l)
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copy(ifi.Addr, b[4+4:])
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}
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return ifi, nil
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}
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