2019-04-29 21:25:05 +00:00
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// Copyright 2018 The gVisor Authors.
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2018-07-09 21:03:03 +00:00
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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2018-04-27 17:37:02 +00:00
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package header
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import (
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"encoding/binary"
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2019-06-13 23:49:09 +00:00
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"gvisor.dev/gvisor/pkg/tcpip"
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2019-09-03 22:59:58 +00:00
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"gvisor.dev/gvisor/pkg/tcpip/buffer"
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2018-04-27 17:37:02 +00:00
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)
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// ICMPv4 represents an ICMPv4 header stored in a byte array.
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type ICMPv4 []byte
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const (
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2019-07-16 20:02:30 +00:00
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// ICMPv4PayloadOffset defines the start of ICMP payload.
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2019-09-03 22:59:58 +00:00
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ICMPv4PayloadOffset = 8
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2018-04-27 17:37:02 +00:00
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2019-07-16 20:02:30 +00:00
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// ICMPv4MinimumSize is the minimum size of a valid ICMP packet.
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ICMPv4MinimumSize = 8
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// ICMPv4ProtocolNumber is the ICMP transport protocol number.
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ICMPv4ProtocolNumber tcpip.TransportProtocolNumber = 1
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2019-09-03 22:59:58 +00:00
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// icmpv4ChecksumOffset is the offset of the checksum field
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// in an ICMPv4 message.
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icmpv4ChecksumOffset = 2
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// icmpv4MTUOffset is the offset of the MTU field
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// in a ICMPv4FragmentationNeeded message.
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icmpv4MTUOffset = 6
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// icmpv4IdentOffset is the offset of the ident field
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// in a ICMPv4EchoRequest/Reply message.
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icmpv4IdentOffset = 4
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// icmpv4SequenceOffset is the offset of the sequence field
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// in a ICMPv4EchoRequest/Reply message.
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icmpv4SequenceOffset = 6
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)
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// ICMPv4Type is the ICMP type field described in RFC 792.
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type ICMPv4Type byte
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// Typical values of ICMPv4Type defined in RFC 792.
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const (
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ICMPv4EchoReply ICMPv4Type = 0
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ICMPv4DstUnreachable ICMPv4Type = 3
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ICMPv4SrcQuench ICMPv4Type = 4
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ICMPv4Redirect ICMPv4Type = 5
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ICMPv4Echo ICMPv4Type = 8
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ICMPv4TimeExceeded ICMPv4Type = 11
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ICMPv4ParamProblem ICMPv4Type = 12
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ICMPv4Timestamp ICMPv4Type = 13
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ICMPv4TimestampReply ICMPv4Type = 14
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ICMPv4InfoRequest ICMPv4Type = 15
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ICMPv4InfoReply ICMPv4Type = 16
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)
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// Values for ICMP code as defined in RFC 792.
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const (
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ICMPv4PortUnreachable = 3
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ICMPv4FragmentationNeeded = 4
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)
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// Type is the ICMP type field.
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func (b ICMPv4) Type() ICMPv4Type { return ICMPv4Type(b[0]) }
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// SetType sets the ICMP type field.
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func (b ICMPv4) SetType(t ICMPv4Type) { b[0] = byte(t) }
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// Code is the ICMP code field. Its meaning depends on the value of Type.
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func (b ICMPv4) Code() byte { return b[1] }
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// SetCode sets the ICMP code field.
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func (b ICMPv4) SetCode(c byte) { b[1] = c }
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// Checksum is the ICMP checksum field.
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func (b ICMPv4) Checksum() uint16 {
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return binary.BigEndian.Uint16(b[icmpv4ChecksumOffset:])
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}
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// SetChecksum sets the ICMP checksum field.
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func (b ICMPv4) SetChecksum(checksum uint16) {
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binary.BigEndian.PutUint16(b[icmpv4ChecksumOffset:], checksum)
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}
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// SourcePort implements Transport.SourcePort.
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func (ICMPv4) SourcePort() uint16 {
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return 0
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}
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// DestinationPort implements Transport.DestinationPort.
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func (ICMPv4) DestinationPort() uint16 {
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return 0
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}
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// SetSourcePort implements Transport.SetSourcePort.
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func (ICMPv4) SetSourcePort(uint16) {
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}
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// SetDestinationPort implements Transport.SetDestinationPort.
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func (ICMPv4) SetDestinationPort(uint16) {
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}
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// Payload implements Transport.Payload.
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func (b ICMPv4) Payload() []byte {
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return b[ICMPv4PayloadOffset:]
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}
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// MTU retrieves the MTU field from an ICMPv4 message.
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func (b ICMPv4) MTU() uint16 {
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return binary.BigEndian.Uint16(b[icmpv4MTUOffset:])
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}
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// SetMTU sets the MTU field from an ICMPv4 message.
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func (b ICMPv4) SetMTU(mtu uint16) {
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binary.BigEndian.PutUint16(b[icmpv4MTUOffset:], mtu)
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}
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// Ident retrieves the Ident field from an ICMPv4 message.
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func (b ICMPv4) Ident() uint16 {
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return binary.BigEndian.Uint16(b[icmpv4IdentOffset:])
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}
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// SetIdent sets the Ident field from an ICMPv4 message.
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func (b ICMPv4) SetIdent(ident uint16) {
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binary.BigEndian.PutUint16(b[icmpv4IdentOffset:], ident)
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}
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// Sequence retrieves the Sequence field from an ICMPv4 message.
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func (b ICMPv4) Sequence() uint16 {
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return binary.BigEndian.Uint16(b[icmpv4SequenceOffset:])
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}
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// SetSequence sets the Sequence field from an ICMPv4 message.
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func (b ICMPv4) SetSequence(sequence uint16) {
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binary.BigEndian.PutUint16(b[icmpv4SequenceOffset:], sequence)
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}
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// ICMPv4Checksum calculates the ICMP checksum over the provided ICMP header,
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// and payload.
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func ICMPv4Checksum(h ICMPv4, vv buffer.VectorisedView) uint16 {
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// Calculate the IPv6 pseudo-header upper-layer checksum.
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xsum := uint16(0)
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for _, v := range vv.Views() {
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xsum = Checksum(v, xsum)
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}
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// h[2:4] is the checksum itself, set it aside to avoid checksumming the checksum.
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h2, h3 := h[2], h[3]
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h[2], h[3] = 0, 0
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xsum = ^Checksum(h, xsum)
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h[2], h[3] = h2, h3
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return xsum
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}
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