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// Copyright 2012 The Go 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 icmp
// An Echo represents an ICMP echo request or reply message body.
type Echo struct {
ID int // identifier
Seq int // sequence number
Data []byte // data
}
// Len implements the Len method of MessageBody interface.
func (p *Echo) Len(proto int) int {
if p == nil {
return 0
}
return 4 + len(p.Data)
}
// Marshal implements the Marshal method of MessageBody interface.
func (p *Echo) Marshal(proto int) ([]byte, error) {
b := make([]byte, 4+len(p.Data))
b[0], b[1] = byte(p.ID>>8), byte(p.ID)
b[2], b[3] = byte(p.Seq>>8), byte(p.Seq)
copy(b[4:], p.Data)
return b, nil
}
// parseEcho parses b as an ICMP echo request or reply message body.
func parseEcho(proto int, b []byte) (MessageBody, error) {
bodyLen := len(b)
if bodyLen < 4 {
return nil, errMessageTooShort
}
p := &Echo{ID: int(b[0])<<8 | int(b[1]), Seq: int(b[2])<<8 | int(b[3])}
if bodyLen > 4 {
p.Data = make([]byte, bodyLen-4)
copy(p.Data, b[4:])
}
return p, nil
}
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