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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package header
import (
"encoding/binary"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
)
// ICMPv4 represents an ICMPv4 header stored in a byte array.
type ICMPv4 []byte
const (
// ICMPv4PayloadOffset defines the start of ICMP payload.
ICMPv4PayloadOffset = 8
// ICMPv4MinimumSize is the minimum size of a valid ICMP packet.
ICMPv4MinimumSize = 8
// ICMPv4ProtocolNumber is the ICMP transport protocol number.
ICMPv4ProtocolNumber tcpip.TransportProtocolNumber = 1
// icmpv4ChecksumOffset is the offset of the checksum field
// in an ICMPv4 message.
icmpv4ChecksumOffset = 2
// icmpv4MTUOffset is the offset of the MTU field
// in a ICMPv4FragmentationNeeded message.
icmpv4MTUOffset = 6
// icmpv4IdentOffset is the offset of the ident field
// in a ICMPv4EchoRequest/Reply message.
icmpv4IdentOffset = 4
// icmpv4SequenceOffset is the offset of the sequence field
// in a ICMPv4EchoRequest/Reply message.
icmpv4SequenceOffset = 6
)
// ICMPv4Type is the ICMP type field described in RFC 792.
type ICMPv4Type byte
// Typical values of ICMPv4Type defined in RFC 792.
const (
ICMPv4EchoReply ICMPv4Type = 0
ICMPv4DstUnreachable ICMPv4Type = 3
ICMPv4SrcQuench ICMPv4Type = 4
ICMPv4Redirect ICMPv4Type = 5
ICMPv4Echo ICMPv4Type = 8
ICMPv4TimeExceeded ICMPv4Type = 11
ICMPv4ParamProblem ICMPv4Type = 12
ICMPv4Timestamp ICMPv4Type = 13
ICMPv4TimestampReply ICMPv4Type = 14
ICMPv4InfoRequest ICMPv4Type = 15
ICMPv4InfoReply ICMPv4Type = 16
)
// Values for ICMP code as defined in RFC 792.
const (
ICMPv4TTLExceeded = 0
ICMPv4PortUnreachable = 3
ICMPv4FragmentationNeeded = 4
)
// Type is the ICMP type field.
func (b ICMPv4) Type() ICMPv4Type { return ICMPv4Type(b[0]) }
// SetType sets the ICMP type field.
func (b ICMPv4) SetType(t ICMPv4Type) { b[0] = byte(t) }
// Code is the ICMP code field. Its meaning depends on the value of Type.
func (b ICMPv4) Code() byte { return b[1] }
// SetCode sets the ICMP code field.
func (b ICMPv4) SetCode(c byte) { b[1] = c }
// Checksum is the ICMP checksum field.
func (b ICMPv4) Checksum() uint16 {
return binary.BigEndian.Uint16(b[icmpv4ChecksumOffset:])
}
// SetChecksum sets the ICMP checksum field.
func (b ICMPv4) SetChecksum(checksum uint16) {
binary.BigEndian.PutUint16(b[icmpv4ChecksumOffset:], checksum)
}
// SourcePort implements Transport.SourcePort.
func (ICMPv4) SourcePort() uint16 {
return 0
}
// DestinationPort implements Transport.DestinationPort.
func (ICMPv4) DestinationPort() uint16 {
return 0
}
// SetSourcePort implements Transport.SetSourcePort.
func (ICMPv4) SetSourcePort(uint16) {
}
// SetDestinationPort implements Transport.SetDestinationPort.
func (ICMPv4) SetDestinationPort(uint16) {
}
// Payload implements Transport.Payload.
func (b ICMPv4) Payload() []byte {
return b[ICMPv4PayloadOffset:]
}
// MTU retrieves the MTU field from an ICMPv4 message.
func (b ICMPv4) MTU() uint16 {
return binary.BigEndian.Uint16(b[icmpv4MTUOffset:])
}
// SetMTU sets the MTU field from an ICMPv4 message.
func (b ICMPv4) SetMTU(mtu uint16) {
binary.BigEndian.PutUint16(b[icmpv4MTUOffset:], mtu)
}
// Ident retrieves the Ident field from an ICMPv4 message.
func (b ICMPv4) Ident() uint16 {
return binary.BigEndian.Uint16(b[icmpv4IdentOffset:])
}
// SetIdent sets the Ident field from an ICMPv4 message.
func (b ICMPv4) SetIdent(ident uint16) {
binary.BigEndian.PutUint16(b[icmpv4IdentOffset:], ident)
}
// Sequence retrieves the Sequence field from an ICMPv4 message.
func (b ICMPv4) Sequence() uint16 {
return binary.BigEndian.Uint16(b[icmpv4SequenceOffset:])
}
// SetSequence sets the Sequence field from an ICMPv4 message.
func (b ICMPv4) SetSequence(sequence uint16) {
binary.BigEndian.PutUint16(b[icmpv4SequenceOffset:], sequence)
}
// ICMPv4Checksum calculates the ICMP checksum over the provided ICMP header,
// and payload.
func ICMPv4Checksum(h ICMPv4, vv buffer.VectorisedView) uint16 {
// Calculate the IPv6 pseudo-header upper-layer checksum.
xsum := uint16(0)
for _, v := range vv.Views() {
xsum = Checksum(v, xsum)
}
// h[2:4] is the checksum itself, set it aside to avoid checksumming the checksum.
h2, h3 := h[2], h[3]
h[2], h[3] = 0, 0
xsum = ^Checksum(h, xsum)
h[2], h[3] = h2, h3
return xsum
}
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