Paddy
3c4f3331d8
Jenkins Production Deployment
Reviewed-on: #8 Co-authored-by: Patrick Mueller <patrick@mueller-patrick.tech> Co-committed-by: Patrick Mueller <patrick@mueller-patrick.tech>
39 lines
1.4 KiB
TypeScript
39 lines
1.4 KiB
TypeScript
import * as crypto from 'crypto';
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// Excludes 0/O, 1/I/L to avoid look-alike confusion when a code is
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// hand-written, read aloud, or typed from a printed fallback under a QR
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// code. 31 symbols * 8 chars ≈ 39.6 bits of entropy - effectively
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// unguessable combined with rate-limiting on the redeem endpoint.
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const CODE_ALPHABET = 'ABCDEFGHJKMNPQRSTUVWXYZ23456789';
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const CODE_LENGTH = 8;
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/**
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* Generates a single random code. Uses crypto.randomInt (uniform, no
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* modulo bias) rather than Math.random() since these gate a real-world
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* concert invitation.
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*/
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export const generateCode = (): string => {
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let code = '';
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for (let i = 0; i < CODE_LENGTH; i++) {
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code += CODE_ALPHABET[crypto.randomInt(CODE_ALPHABET.length)];
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}
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return code;
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};
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/**
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* Generates a code guaranteed not to collide with any row `existingCodes`
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* already contains, tries up to `maxAttempts` times before giving up.
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* Collisions are astronomically unlikely at this entropy - this exists as
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* a correctness backstop, not because collisions are expected.
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*/
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export const generateUniqueCode = (existingCodes: Set<string>, maxAttempts = 20): string => {
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for (let i = 0; i < maxAttempts; i++) {
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const candidate = generateCode();
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if (!existingCodes.has(candidate)) {
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existingCodes.add(candidate);
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return candidate;
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}
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}
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throw new Error('Could not generate a unique voucher code after ' + maxAttempts + ' attempts');
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};
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