| // 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" |
| |
| "github.com/google/netstack/tcpip" |
| "github.com/google/netstack/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 ( |
| 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 |
| } |