// ParseMessage parses b as an ICMP message. Proto must be
// iana.ProtocolICMP or iana.ProtocolIPv6ICMP.
func ParseMessage(proto int, b []byte) (*Message, error) {
if len(b) < 4 {
return nil, errors.New("message too short")
}
var err error
switch proto {
case iana.ProtocolICMP:
m := &Message{Type: ipv4.ICMPType(b[0]), Code: int(b[1]), Checksum: int(b[2])<<8 | int(b[3])}
switch m.Type {
case ipv4.ICMPTypeEcho, ipv4.ICMPTypeEchoReply:
m.Body, err = parseEcho(b[4:])
if err != nil {
return nil, err
}
default:
m.Body = &DefaultMessageBody{Data: b[4:]}
}
return m, nil
case iana.ProtocolIPv6ICMP:
m := &Message{Type: ipv6.ICMPType(b[0]), Code: int(b[1]), Checksum: int(b[2])<<8 | int(b[3])}
switch m.Type {
case ipv6.ICMPTypeEchoRequest, ipv6.ICMPTypeEchoReply:
m.Body, err = parseEcho(b[4:])
if err != nil {
return nil, err
}
default:
m.Body = &DefaultMessageBody{Data: b[4:]}
}
return m, nil
default:
return nil, errors.New("unknown protocol")
}
}
// parseICMPMessage parses b as an ICMP message.
func parseICMPMessage(b []byte) (*icmpMessage, error) {
msglen := len(b)
if msglen < 4 {
return nil, errors.New("message too short")
}
m := &icmpMessage{Type: ipv4.ICMPType(b[0]), Code: int(b[1]), Checksum: int(b[2])<<8 | int(b[3])}
if msglen > 4 {
var err error
switch m.Type {
case ipv4.ICMPTypeEcho, ipv4.ICMPTypeEchoReply:
m.Body, err = parseICMPEcho(b[4:])
if err != nil {
return nil, err
}
}
}
return m, nil
}