git.squeep.com Git - websub-hub/blob - src/common.js

   1 /* eslint-disable security/detect-object-injection */
   2 'use strict';
   3
   4 /**
   5  * Assorted utility functions.
   6  */
   7
   8 const { common } = require('@squeep/api-dingus');
   9
  10 const { randomBytes, getHashes } = require('crypto');
  11 const { promisify } = require('util');
  12
  13
  14 /**
  15  * Wrap this in a promise, as crypto.randomBytes is capable of blocking.
  16  */
  17 const randomBytesAsync = promisify(randomBytes);
  18
  19
  20 /**
  21  * The HMAC hashes we are willing to support.
  22  * @param {String} algorithm
  23  * @returns {Boolean}
  24  */
  25 const validHash = (algorithm) => getHashes()
  26   .filter((h) => h.match(/^sha[0-9]+$/))
  27   .includes(algorithm);
  28
  29 /**
  30  * Recursively freeze an object.
  31  * @param {Object} o
  32  * @returns {Object}
  33  */
  34 const freezeDeep = (o) => {
  35   Object.freeze(o);
  36   Object.getOwnPropertyNames(o).forEach((prop) => {
  37     if (Object.hasOwnProperty.call(o, prop)
  38     &&  ['object', 'function'].includes(typeof o[prop])
  39     &&  !Object.isFrozen(o[prop])) {
  40       return freezeDeep(o[prop]);
  41     }
  42   });
  43   return o;
  44 }
  45
  46
  47 /**
  48  * Pick out useful axios response fields.
  49  * @param {*} res
  50  * @returns
  51  */
  52 const axiosResponseLogData = (res) => {
  53   const data = common.pick(res, [
  54     'status',
  55     'statusText',
  56     'headers',
  57     'elapsedTimeMs',
  58     'data',
  59   ]);
  60   if (data.data) {
  61     data.data = logTruncate(data.data, 100);
  62   }
  63   return data;
  64 };
  65
  66
  67 /**
  68  * Fallback values, if not configured.
  69  * @returns {Object}
  70  */
  71 const topicLeaseDefaults = () => {
  72   return Object.freeze({
  73     leaseSecondsPreferred: 86400 * 10,
  74     leaseSecondsMin: 86400 * 1,
  75     leaseSecondsMax: 86400 * 365,
  76   });
  77 };
  78
  79
  80 /**
  81  * Pick from a range, constrained, with some fuzziness.
  82  * @param {Number} attempt
  83  * @param {Number[]} delays
  84  * @param {Number} jitter
  85  * @returns {Number}
  86  */
  87   const attemptRetrySeconds = (attempt, retryBackoffSeconds = [60, 120, 360, 1440, 7200, 43200, 86400], jitter = 0.618) => {
  88   const maxAttempt = retryBackoffSeconds.length - 1;
  89   if (typeof attempt !== 'number' || attempt < 0) {
  90     attempt = 0;
  91   } else if (attempt > maxAttempt) {
  92     attempt = maxAttempt;
  93   }
  94   // eslint-disable-next-line security/detect-object-injection
  95   let seconds = retryBackoffSeconds[attempt];
  96   seconds += Math.floor(Math.random() * seconds * jitter);
  97   return seconds;
  98 }
  99
 100
 101 /**
 102  * Return array items split as an array of arrays of no more than per items each.
 103  * @param {Array} array
 104  * @param {Number} per
 105  */
 106  const arrayChunk = (array, per = 1) => {
 107   const nChunks = Math.ceil(array.length / per);
 108   return Array.from(Array(nChunks), (_, i) => array.slice(i * per, (i + 1) * per));
 109 }
 110
 111
 112 /**
 113  * Be paranoid about blowing the stack when pushing to an array.
 114  * @param {Array} dst
 115  * @param {Array} src
 116  */
 117  const stackSafePush = (dst, src) => {
 118   const jsEngineMaxArguments = 2**16; // Current as of Node 12
 119   arrayChunk(src, jsEngineMaxArguments).forEach((items) => {
 120     Array.prototype.push.apply(dst, items);
 121   });
 122 }
 123
 124
 125 /**
 126  * Limit length of string to keep logs sane
 127  * @param {String} str
 128  * @param {Number} len
 129  * @returns {String}
 130  */
 131 const logTruncate = (str, len) => {
 132   if (typeof str !== 'string' || str.toString().length <= len) {
 133     return str;
 134   }
 135   return str.toString().slice(0, len) + `... (${str.toString().length} bytes)`;
 136 };
 137
 138 module.exports = {
 139   ...common,
 140   arrayChunk,
 141   attemptRetrySeconds,
 142   axiosResponseLogData,
 143   freezeDeep,
 144   logTruncate,
 145   randomBytesAsync,
 146   stackSafePush,
 147   topicLeaseDefaults,
 148   validHash,
 149 };