Update

vendor/tailscale.com/derp/loanedbytes.go

@@ -0,0 +1,33 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+package derp
+
+import (
+	"bytes"
+	"io"
+)
+
+// LoanedBytes is a packet payload lent to a callee for the duration of
+// a call. The lender reuses the memory once the call returns, so the
+// callee must not retain it; Clone gives it a copy to keep.
+//
+// It deliberately has no accessor for the underlying slice.
+type LoanedBytes struct {
+	bs []byte
+}
+
+// LoanBytes lends b for the duration of the call it's passed to.
+func LoanBytes(b []byte) LoanedBytes { return LoanedBytes{bs: b} }
+
+// Len returns the number of bytes.
+func (b LoanedBytes) Len() int { return len(b.bs) }
+
+// WriteTo writes the bytes to w.
+func (b LoanedBytes) WriteTo(w io.Writer) (int64, error) {
+	n, err := w.Write(b.bs)
+	return int64(n), err
+}
+
+// Clone returns a copy of the bytes that the caller owns.
+func (b LoanedBytes) Clone() []byte { return bytes.Clone(b.bs) }