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| 1 | +// The implementation in this file generates UUIDs in v4 format and is suitable |
| 2 | +// for use as a UUID in LaunchDarkly events. It is not a rigorous implementation. |
| 3 | + |
| 4 | +// It uses crypto.randomUUID when available. |
| 5 | +// If crypto.randomUUID is not available, then it uses random values and forms |
| 6 | +// the UUID itself. |
| 7 | +// When possible it uses crypto.getRandomValues, but it can use Math.random |
| 8 | +// if crypto.getRandomValues is not available. |
| 9 | + |
| 10 | +// UUIDv4 Struct definition. |
| 11 | +// https://www.rfc-archive.org/getrfc.php?rfc=4122 |
| 12 | +// Appendix A. Appendix A - Sample Implementation |
| 13 | +const timeLow = { |
| 14 | + start: 0, |
| 15 | + end: 3, |
| 16 | +}; |
| 17 | +const timeMid = { |
| 18 | + start: 4, |
| 19 | + end: 5, |
| 20 | +}; |
| 21 | +const timeHiAndVersion = { |
| 22 | + start: 6, |
| 23 | + end: 7, |
| 24 | +}; |
| 25 | +const clockSeqHiAndReserved = { |
| 26 | + start: 8, |
| 27 | + end: 8, |
| 28 | +}; |
| 29 | +const clockSeqLow = { |
| 30 | + start: 9, |
| 31 | + end: 9, |
| 32 | +}; |
| 33 | +const nodes = { |
| 34 | + start: 10, |
| 35 | + end: 15, |
| 36 | +}; |
| 37 | + |
| 38 | +function getRandom128bit(): number[] { |
| 39 | + if (crypto && crypto.getRandomValues) { |
| 40 | + const typedArray = new Uint8Array(16); |
| 41 | + crypto.getRandomValues(typedArray); |
| 42 | + return [...typedArray.values()]; |
| 43 | + } |
| 44 | + const values = []; |
| 45 | + for (let index = 0; index < 16; index += 1) { |
| 46 | + // Math.random is 0-1 with inclusive min and exclusive max. |
| 47 | + values.push(Math.floor(Math.random() * 256)); |
| 48 | + } |
| 49 | + return values; |
| 50 | +} |
| 51 | + |
| 52 | +function hex(bytes: number[], range: { start: number; end: number }): string { |
| 53 | + let strVal = ''; |
| 54 | + for (let index = range.start; index <= range.end; index += 1) { |
| 55 | + strVal += bytes[index].toString(16).padStart(2, '0'); |
| 56 | + } |
| 57 | + return strVal; |
| 58 | +} |
| 59 | + |
| 60 | +/** |
| 61 | + * Given a list of 16 random bytes generate a UUID in v4 format. |
| 62 | + * |
| 63 | + * Note: The input bytes are modified to conform to the requirements of UUID v4. |
| 64 | + * |
| 65 | + * @param bytes A list of 16 bytes. |
| 66 | + * @returns A UUID v4 string. |
| 67 | + */ |
| 68 | +export function formatDataAsUuidV4(bytes: number[]): string { |
| 69 | + // https://www.rfc-archive.org/getrfc.php?rfc=4122 |
| 70 | + // 4.4. Algorithms for Creating a UUID from Truly Random or |
| 71 | + // Pseudo-Random Numbers |
| 72 | + |
| 73 | + // Set the two most significant bits (bits 6 and 7) of the clock_seq_hi_and_reserved to zero and |
| 74 | + // one, respectively. |
| 75 | + // eslint-disable-next-line no-bitwise, no-param-reassign |
| 76 | + bytes[clockSeqHiAndReserved.start] = (bytes[clockSeqHiAndReserved.start] | 0x80) & 0xbf; |
| 77 | + // Set the four most significant bits (bits 12 through 15) of the time_hi_and_version field to |
| 78 | + // the 4-bit version number from Section 4.1.3. |
| 79 | + // eslint-disable-next-line no-bitwise, no-param-reassign |
| 80 | + bytes[timeHiAndVersion.start] = (bytes[timeHiAndVersion.start] & 0x0f) | 0x40; |
| 81 | + |
| 82 | + return ( |
| 83 | + `${hex(bytes, timeLow)}-${hex(bytes, timeMid)}-${hex(bytes, timeHiAndVersion)}-` + |
| 84 | + `${hex(bytes, clockSeqHiAndReserved)}${hex(bytes, clockSeqLow)}-${hex(bytes, nodes)}` |
| 85 | + ); |
| 86 | +} |
| 87 | + |
| 88 | +export function fallbackUuidV4(): string { |
| 89 | + const bytes = getRandom128bit(); |
| 90 | + return formatDataAsUuidV4(bytes); |
| 91 | +} |
| 92 | + |
| 93 | +export default function randomUuidV4(): string { |
| 94 | + if (typeof crypto !== undefined && typeof crypto.randomUUID === 'function') { |
| 95 | + return crypto.randomUUID(); |
| 96 | + } |
| 97 | + |
| 98 | + return fallbackUuidV4(); |
| 99 | +} |
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