(cache)homebridge-june-oven/src/pairing.ts at b68b7a7a08affbad45485eed2ada4cc1a1524a69 · keithah/homebridge-june-oven · GitHub

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import { createHash, randomBytes, randomInt } from 'crypto';
import { EventEmitter } from 'events';
import sodium from 'libsodium-wrappers';
import WebSocket from 'ws';
import { fetchJsonWithTimeout, isRetryableHttpStatus } from './http';
import { parseJuneTokenResponse } from './protocol';
import {
  JUNE_API_URL,
  JUNE_APP_VERSION,
  JUNE_CLIENT_ID,
  JUNE_CLIENT_SECRET,
  JUNE_PLATFORM_VERSION,
  JUNE_USER_AGENT,
  JUNE_WS_URL,
  SRP_G,
  SRP_N_HEX,
} from './settings';

const SRP_N = BigInt(`0x${SRP_N_HEX}`);
const ASSOCIATION_MAX_DELAY_MS = 30_000;
const PAIRING_SESSION_TIMEOUT_MS = 5 * 60_000;

export function calculateAssociationDelay(attempt: number, random = Math.random): number {
  const exponential = Math.min(ASSOCIATION_MAX_DELAY_MS, 3_000 * 2 ** Math.max(0, attempt));
  return Math.min(ASSOCIATION_MAX_DELAY_MS, Math.round(exponential * (0.75 + random() * 0.5)));
}
const PAD_LEN = (SRP_N.toString(2).length + 7) >> 3;
const DAMM = [
  [0, 3, 1, 7, 5, 9, 8, 6, 4, 2],
  [7, 0, 9, 2, 1, 5, 4, 8, 6, 3],
  [4, 2, 0, 6, 8, 7, 1, 3, 5, 9],
  [1, 7, 5, 0, 9, 8, 3, 4, 2, 6],
  [6, 1, 2, 3, 0, 4, 5, 9, 7, 8],
  [3, 6, 7, 4, 2, 0, 9, 5, 8, 1],
  [5, 8, 6, 9, 7, 2, 0, 1, 3, 4],
  [8, 9, 4, 5, 3, 6, 2, 0, 1, 7],
  [9, 4, 3, 8, 6, 1, 7, 2, 0, 5],
  [2, 5, 8, 1, 4, 3, 6, 7, 9, 0],
];

export type PairingState = 'starting' | 'waiting-for-oven' | 'posting-companion' | 'waiting-for-associated' | 'paired' | 'failed';

export interface PairingStatus {
  id: string;
  state: PairingState;
  shownCode?: string;
  error?: string;
  oven?: PairedOvenIdentity;
}

export interface PairedOvenIdentity {
  name: string;
  preheatSwitchName: string;
  readySensor: boolean;
  doneSensor: boolean;
  defaultMode: string;
  defaultTempF: number;
  tempUnit: 'F' | 'C';
  ovenId: string;
  deviceId: string;
  deviceName: string;
  password: string;
  ed25519SeedHex: string;
  accessToken: string;
  refreshToken: string;
  clientId: string;
  clientSecret: string;
}

export function damm(input: string): number {
  let state = 0;
  for (const char of input) {
    state = DAMM[state][Number(char)];
  }
  return state;
}

export function buildShownCode(serverCode: string, twoDigits = randomInt(0, 100)): string {
  const base = `${serverCode}${twoDigits.toString().padStart(2, '0')}`;
  return `${base}${damm(base)}`;
}

export function modPow(base: bigint, exponent: bigint, modulus: bigint): bigint {
  let result = 1n;
  let b = base % modulus;
  let e = exponent;
  while (e > 0n) {
    if (e & 1n) {
      result = (result * b) % modulus;
    }
    e >>= 1n;
    b = (b * b) % modulus;
  }
  return result;
}

function sha1(...chunks: Buffer[]): Buffer {
  const hash = createHash('sha1');
  chunks.forEach(chunk => hash.update(chunk));
  return hash.digest();
}

function pad(value: bigint): Buffer {
  return bigintToBuffer(value, PAD_LEN);
}

function bigintToBuffer(value: bigint, minLength = 0): Buffer {
  if (value === 0n) {
    return Buffer.alloc(Math.max(1, minLength));
  }
  let hex = value.toString(16);
  if (hex.length % 2) {
    hex = `0${hex}`;
  }
  const raw = Buffer.from(hex, 'hex');
  if (raw.length >= minLength) {
    return raw;
  }
  return Buffer.concat([Buffer.alloc(minLength - raw.length), raw]);
}

export class SrpServer {
  public readonly salt: Buffer;
  public readonly B: bigint;
  private readonly verifier: bigint;
  private readonly multiplier: bigint;
  private readonly secretB: bigint;

  constructor(password: string, salt = randomBytes(16), secretB = BigInt(`0x${randomBytes(32).toString('hex')}`) % SRP_N) {
    this.salt = salt;
    const identityHash = sha1(Buffer.from(`user:${password}`, 'utf8'));
    const x = BigInt(`0x${sha1(this.salt, identityHash).toString('hex')}`);
    this.verifier = modPow(SRP_G, x, SRP_N);
    this.multiplier = BigInt(`0x${sha1(pad(SRP_N), pad(SRP_G)).toString('hex')}`);
    this.secretB = secretB;
    this.B = (this.multiplier * this.verifier + modPow(SRP_G, this.secretB, SRP_N)) % SRP_N;
  }

  public secret(A: bigint): Buffer {
    const u = BigInt(`0x${sha1(pad(A), pad(this.B)).toString('hex')}`);
    const S = modPow((A * modPow(this.verifier, u, SRP_N)) % SRP_N, this.secretB, SRP_N);
    return bigintToBuffer(S);
  }

  public saltBase64(): string {
    const session = this.sessionFactory(id, deviceName);
    this.sessions.set(id, session);
    const statusListener = (status: PairingStatus) => {
      if (this.sessions.get(id) !== session) {
        return;
      }
      if (isTerminal(status.state)) {
        this.scheduleEviction(id, session);
      }
    };
    this.statusListeners.set(id, statusListener);
    session.on('status', statusListener);
    try {
      const status = await session.begin();
      if (isTerminal(status.state)) {
        this.scheduleEviction(id, session);
      }
      return status;
    } catch (error) {
      this.remove(id, session);
      throw error;
    }
  }

  public status(id: string): PairingStatus {
    const session = this.sessions.get(id);
    if (!session) {
      return { id, state: 'failed', error: 'Pairing session not found.' };
    }
    return session.currentStatus();
  }

  public cancel(id: string): void {
    const session = this.sessions.get(id);
    if (session) {
      this.remove(id, session);
    }
  }

  private scheduleEviction(id: string, session: JunePairingSession): void {
    if (this.evictionTimers.has(id)) {
      return;
    }
    const timer = setTimeout(() => this.remove(id, session), this.terminalTtlMs);
    timer.unref?.();
    this.evictionTimers.set(id, timer);
  }

  private remove(id: string, session: JunePairingSession): void {
    const timer = this.evictionTimers.get(id);
    if (timer) {
      clearTimeout(timer);
      this.evictionTimers.delete(id);
    }
    if (this.sessions.get(id) !== session) {
      return;
    }
    const listener = this.statusListeners.get(id);
    if (listener) {
      session.removeListener('status', listener);
      this.statusListeners.delete(id);
    }
    this.sessions.delete(id);
    session.destroy();
  }
}

function isTerminal(state: PairingState): boolean {
  return state === 'paired' || state === 'failed';
}

function findLongBase64(input: string): string | undefined {
  return input.match(/"([A-Za-z0-9+/=]{300,})"/)?.[1];
}