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30 lines
965 B
Go
30 lines
965 B
Go
// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package packet
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import (
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crand "crypto/rand"
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"encoding/binary"
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)
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// ICMPEchoPayload generates a new random ID/Sequence pair, and returns a uint32
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// derived from them, along with the id, sequence and given payload in a buffer.
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// It returns an error if the random source could not be read.
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func ICMPEchoPayload(payload []byte) (idSeq uint32, buf []byte) {
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buf = make([]byte, len(payload)+4)
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// make a completely random id/sequence combo, which is very unlikely to
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// collide with a running ping sequence on the host system. Errors are
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// ignored, that would result in collisions, but errors reading from the
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// random device are rare, and will cause this process universe to soon end.
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crand.Read(buf[:4])
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idSeq = binary.LittleEndian.Uint32(buf)
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copy(buf[4:], payload)
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return
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}
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