| // 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" |
| ) |
| |
| // 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 |
| |
| // ICMPv4MinimumErrorPayloadSize Is the smallest number of bytes of an |
| // errant packet's transport layer that an ICMP error type packet should |
| // attempt to send as per RFC 792 (see each type) and RFC 1122 |
| // section 3.2.2 which states: |
| // Every ICMP error message includes the Internet header and at |
| // least the first 8 data octets of the datagram that triggered |
| // the error; more than 8 octets MAY be sent; this header and data |
| // MUST be unchanged from the received datagram. |
| // |
| // RFC 792 shows: |
| // 0 1 2 3 |
| // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| // | Type | Code | Checksum | |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| // | unused | |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| // | Internet Header + 64 bits of Original Data Datagram | |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| ICMPv4MinimumErrorPayloadSize = 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 an ICMPv4FragmentationNeeded message. |
| icmpv4MTUOffset = 6 |
| |
| // icmpv4IdentOffset is the offset of the ident field |
| // in an ICMPv4EchoRequest/Reply message. |
| icmpv4IdentOffset = 4 |
| |
| // icmpv4PointerOffset is the offset of the pointer field |
| // in an ICMPv4ParamProblem message. |
| icmpv4PointerOffset = 4 |
| |
| // icmpv4SequenceOffset is the offset of the sequence field |
| // in an ICMPv4EchoRequest/Reply message. |
| icmpv4SequenceOffset = 6 |
| ) |
| |
| // ICMPv4Type is the ICMP type field described in RFC 792. |
| type ICMPv4Type byte |
| |
| // ICMPv4Code is the ICMP code field described in RFC 792. |
| type ICMPv4Code 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 |
| ) |
| |
| // ICMP codes for ICMPv4 Time Exceeded messages as defined in RFC 792. |
| const ( |
| ICMPv4TTLExceeded ICMPv4Code = 0 |
| ICMPv4ReassemblyTimeout ICMPv4Code = 1 |
| ) |
| |
| // ICMP codes for ICMPv4 Destination Unreachable messages as defined in RFC 792. |
| const ( |
| ICMPv4NetUnreachable ICMPv4Code = 0 |
| ICMPv4HostUnreachable ICMPv4Code = 1 |
| ICMPv4ProtoUnreachable ICMPv4Code = 2 |
| ICMPv4PortUnreachable ICMPv4Code = 3 |
| ICMPv4FragmentationNeeded ICMPv4Code = 4 |
| ) |
| |
| // ICMPv4UnusedCode is a code to use in ICMP messages where no code is needed. |
| const ICMPv4UnusedCode ICMPv4Code = 0 |
| |
| // 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() ICMPv4Code { return ICMPv4Code(b[1]) } |
| |
| // SetCode sets the ICMP code field. |
| func (b ICMPv4) SetCode(c ICMPv4Code) { b[1] = byte(c) } |
| |
| // Pointer returns the pointer field in a Parameter Problem packet. |
| func (b ICMPv4) Pointer() byte { return b[icmpv4PointerOffset] } |
| |
| // SetPointer sets the pointer field in a Parameter Problem packet. |
| func (b ICMPv4) SetPointer(c byte) { b[icmpv4PointerOffset] = 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, payloadCsum uint16) uint16 { |
| xsum := payloadCsum |
| |
| // h[2:4] is the checksum itself, skip it to avoid checksumming the checksum. |
| xsum = Checksum(h[:2], xsum) |
| xsum = Checksum(h[4:], xsum) |
| |
| return ^xsum |
| } |