| // Copyright 2016 The Netstack 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 header |
| |
| import ( |
| "encoding/binary" |
| |
| "github.com/google/netstack/tcpip" |
| ) |
| |
| // ICMPv4 represents an ICMPv4 header stored in a byte array. |
| type ICMPv4 []byte |
| |
| const ( |
| // ICMPv4MinimumSize is the minimum size of a valid ICMP packet. |
| ICMPv4MinimumSize = 4 |
| |
| // ICMPv4EchoMinimumSize is the minimum size of a valid ICMP echo packet. |
| ICMPv4EchoMinimumSize = 6 |
| |
| // ICMPv4ProtocolNumber is the ICMP transport protocol number. |
| ICMPv4ProtocolNumber tcpip.TransportProtocolNumber = 1 |
| ) |
| |
| // 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 |
| ) |
| |
| // 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 } |
| |
| // SetChecksum sets the ICMP checksum field. |
| func (b ICMPv4) SetChecksum(checksum uint16) { |
| binary.BigEndian.PutUint16(b[2:], checksum) |
| } |
| |
| // CalculateChecksum calculates the checksum of the ipv4 header. |
| func (b ICMPv4) CalculateChecksum(prev uint16) uint16 { |
| return Checksum(b[:], prev) |
| } |