mirror of
https://github.com/tailscale/tailscale.git
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57 lines
1.1 KiB
Go
57 lines
1.1 KiB
Go
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package fastuuid implements a UUID construction using an in process CSPRNG.
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package fastuuid
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import (
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crand "crypto/rand"
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"encoding/binary"
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"io"
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"math/rand/v2"
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"sync"
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"github.com/google/uuid"
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)
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// NewUUID returns a new UUID using a pool of generators, good for highly
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// concurrent use.
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func NewUUID() uuid.UUID {
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g := pool.Get().(*generator)
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defer pool.Put(g)
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return g.newUUID()
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}
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var pool = sync.Pool{
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New: func() any {
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return newGenerator()
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},
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}
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type generator struct {
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rng rand.ChaCha8
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}
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func seed() [32]byte {
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var r [32]byte
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if _, err := io.ReadFull(crand.Reader, r[:]); err != nil {
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panic(err)
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}
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return r
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}
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func newGenerator() *generator {
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return &generator{
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rng: *rand.NewChaCha8(seed()),
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}
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}
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func (g *generator) newUUID() uuid.UUID {
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var u uuid.UUID
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binary.NativeEndian.PutUint64(u[:8], g.rng.Uint64())
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binary.NativeEndian.PutUint64(u[8:], g.rng.Uint64())
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u[6] = (u[6] & 0x0f) | 0x40 // Version 4
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u[8] = (u[8] & 0x3f) | 0x80 // Variant 10
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return u
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}
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