+++ /dev/null
-// Copyright 2012 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 icmp provides basic functions for the manipulation of
-// messages used in the Internet Control Message Protocols,
-// ICMPv4 and ICMPv6.
-//
-// ICMPv4 and ICMPv6 are defined in RFC 792 and RFC 4443.
-// Multi-part message support for ICMP is defined in RFC 4884.
-// ICMP extensions for MPLS are defined in RFC 4950.
-// ICMP extensions for interface and next-hop identification are
-// defined in RFC 5837.
-package icmp // import "golang.org/x/net/icmp"
-
-import (
- "encoding/binary"
- "errors"
- "net"
- "syscall"
-
- "golang.org/x/net/internal/iana"
- "golang.org/x/net/ipv4"
- "golang.org/x/net/ipv6"
-)
-
-// BUG(mikio): This package is not implemented on NaCl and Plan 9.
-
-var (
- errMessageTooShort = errors.New("message too short")
- errHeaderTooShort = errors.New("header too short")
- errBufferTooShort = errors.New("buffer too short")
- errOpNoSupport = errors.New("operation not supported")
- errNoExtension = errors.New("no extension")
- errInvalidExtension = errors.New("invalid extension")
-)
-
-func checksum(b []byte) uint16 {
- csumcv := len(b) - 1 // checksum coverage
- s := uint32(0)
- for i := 0; i < csumcv; i += 2 {
- s += uint32(b[i+1])<<8 | uint32(b[i])
- }
- if csumcv&1 == 0 {
- s += uint32(b[csumcv])
- }
- s = s>>16 + s&0xffff
- s = s + s>>16
- return ^uint16(s)
-}
-
-// A Type represents an ICMP message type.
-type Type interface {
- Protocol() int
-}
-
-// A Message represents an ICMP message.
-type Message struct {
- Type Type // type, either ipv4.ICMPType or ipv6.ICMPType
- Code int // code
- Checksum int // checksum
- Body MessageBody // body
-}
-
-// Marshal returns the binary encoding of the ICMP message m.
-//
-// For an ICMPv4 message, the returned message always contains the
-// calculated checksum field.
-//
-// For an ICMPv6 message, the returned message contains the calculated
-// checksum field when psh is not nil, otherwise the kernel will
-// compute the checksum field during the message transmission.
-// When psh is not nil, it must be the pseudo header for IPv6.
-func (m *Message) Marshal(psh []byte) ([]byte, error) {
- var mtype int
- switch typ := m.Type.(type) {
- case ipv4.ICMPType:
- mtype = int(typ)
- case ipv6.ICMPType:
- mtype = int(typ)
- default:
- return nil, syscall.EINVAL
- }
- b := []byte{byte(mtype), byte(m.Code), 0, 0}
- if m.Type.Protocol() == iana.ProtocolIPv6ICMP && psh != nil {
- b = append(psh, b...)
- }
- if m.Body != nil && m.Body.Len(m.Type.Protocol()) != 0 {
- mb, err := m.Body.Marshal(m.Type.Protocol())
- if err != nil {
- return nil, err
- }
- b = append(b, mb...)
- }
- if m.Type.Protocol() == iana.ProtocolIPv6ICMP {
- if psh == nil { // cannot calculate checksum here
- return b, nil
- }
- off, l := 2*net.IPv6len, len(b)-len(psh)
- binary.BigEndian.PutUint32(b[off:off+4], uint32(l))
- }
- s := checksum(b)
- // Place checksum back in header; using ^= avoids the
- // assumption the checksum bytes are zero.
- b[len(psh)+2] ^= byte(s)
- b[len(psh)+3] ^= byte(s >> 8)
- return b[len(psh):], nil
-}
-
-var parseFns = map[Type]func(int, []byte) (MessageBody, error){
- ipv4.ICMPTypeDestinationUnreachable: parseDstUnreach,
- ipv4.ICMPTypeTimeExceeded: parseTimeExceeded,
- ipv4.ICMPTypeParameterProblem: parseParamProb,
-
- ipv4.ICMPTypeEcho: parseEcho,
- ipv4.ICMPTypeEchoReply: parseEcho,
-
- ipv6.ICMPTypeDestinationUnreachable: parseDstUnreach,
- ipv6.ICMPTypePacketTooBig: parsePacketTooBig,
- ipv6.ICMPTypeTimeExceeded: parseTimeExceeded,
- ipv6.ICMPTypeParameterProblem: parseParamProb,
-
- ipv6.ICMPTypeEchoRequest: parseEcho,
- ipv6.ICMPTypeEchoReply: parseEcho,
-}
-
-// ParseMessage parses b as an ICMP message.
-// Proto must be either the ICMPv4 or ICMPv6 protocol number.
-func ParseMessage(proto int, b []byte) (*Message, error) {
- if len(b) < 4 {
- return nil, errMessageTooShort
- }
- var err error
- m := &Message{Code: int(b[1]), Checksum: int(binary.BigEndian.Uint16(b[2:4]))}
- switch proto {
- case iana.ProtocolICMP:
- m.Type = ipv4.ICMPType(b[0])
- case iana.ProtocolIPv6ICMP:
- m.Type = ipv6.ICMPType(b[0])
- default:
- return nil, syscall.EINVAL
- }
- if fn, ok := parseFns[m.Type]; !ok {
- m.Body, err = parseDefaultMessageBody(proto, b[4:])
- } else {
- m.Body, err = fn(proto, b[4:])
- }
- if err != nil {
- return nil, err
- }
- return m, nil
-}
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