47 lines
1.3 KiB
TypeScript
47 lines
1.3 KiB
TypeScript
// Copyright 2024 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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import { stringify } from 'uuid';
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import { getRandomBytes } from '../Crypto';
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export type GeneratedMessageIdType = Readonly<{
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id: string;
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received_at: number;
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}>;
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// See https://datatracker.ietf.org/doc/html/draft-ietf-uuidrev-rfc4122bis-00#section-5.7
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export function generateMessageId(counter: number): GeneratedMessageIdType {
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const uuid = getRandomBytes(16);
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/* eslint-disable no-bitwise */
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// We compose uuid out of 48 bits (6 bytes of) timestamp-like counter:
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// `incrementMessageCounter`. Note big-endian encoding (which ensures proper
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// lexicographical order), and floating point divisions (because `&` operator
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// coerces to 32bit integers)
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uuid[0] = (counter / 0x10000000000) & 0xff;
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uuid[1] = (counter / 0x00100000000) & 0xff;
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uuid[2] = (counter / 0x00001000000) & 0xff;
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uuid[3] = (counter / 0x00000010000) & 0xff;
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uuid[4] = (counter / 0x00000000100) & 0xff;
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uuid[5] = (counter / 0x00000000001) & 0xff;
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// Mask out 4 bits of version number
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uuid[6] &= 0x0f;
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// And set the version to 7
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uuid[6] |= 0x70;
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// Mask out 2 bits of variant
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uuid[8] &= 0x3f;
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// And set it to "2"
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uuid[8] |= 0x80;
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/* eslint-enable no-bitwise */
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return {
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id: stringify(uuid),
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received_at: counter,
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};
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}
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