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 /**
  31  * Return an array containing x if x is not an array.
  32  * @param {*} x
  33  */
  34 const ensureArray = (x) => {
  35   if (x === undefined) {
  36     return [];
  37   }
  38   if (!Array.isArray(x)) {
  39     return Array(x);
  40   }
  41   return x;
  42 };
  43
  44
  45 /**
  46  * Recursively freeze an object.
  47  * @param {Object} o
  48  * @returns {Object}
  49  */
  50 const freezeDeep = (o) => {
  51   Object.freeze(o);
  52   Object.getOwnPropertyNames(o).forEach((prop) => {
  53     if (Object.hasOwnProperty.call(o, prop)
  54     &&  ['object', 'function'].includes(typeof o[prop])
  55     &&  !Object.isFrozen(o[prop])) {
  56       return freezeDeep(o[prop]);
  57     }
  58   });
  59   return o;
  60 };
  61
  62
  63 /**
  64  * Pick out useful axios response fields.
  65  * @param {*} res
  66  * @returns
  67  */
  68 const axiosResponseLogData = (res) => {
  69   const data = common.pick(res, [
  70     'status',
  71     'statusText',
  72     'headers',
  73     'elapsedTimeMs',
  74     'data',
  75   ]);
  76   if (data.data) {
  77     data.data = logTruncate(data.data, 100);
  78   }
  79   return data;
  80 };
  81
  82
  83 /**
  84  * Fallback values, if not configured.
  85  * @returns {Object}
  86  */
  87 const topicLeaseDefaults = () => {
  88   return Object.freeze({
  89     leaseSecondsPreferred: 86400 * 10,
  90     leaseSecondsMin: 86400 * 1,
  91     leaseSecondsMax: 86400 * 365,
  92   });
  93 };
  94
  95
  96 /**
  97  * Pick from a range, constrained, with some fuzziness.
  98  * @param {Number} attempt
  99  * @param {Number[]} delays
 100  * @param {Number} jitter
 101  * @returns {Number}
 102  */
 103 const attemptRetrySeconds = (attempt, retryBackoffSeconds = [60, 120, 360, 1440, 7200, 43200, 86400], jitter = 0.618) => {
 104   const maxAttempt = retryBackoffSeconds.length - 1;
 105   if (typeof attempt !== 'number' || attempt < 0) {
 106     attempt = 0;
 107   } else if (attempt > maxAttempt) {
 108     attempt = maxAttempt;
 109   }
 110   // eslint-disable-next-line security/detect-object-injection
 111   let seconds = retryBackoffSeconds[attempt];
 112   seconds += Math.floor(Math.random() * seconds * jitter);
 113   return seconds;
 114 };
 115
 116
 117 /**
 118  * Return array items split as an array of arrays of no more than per items each.
 119  * @param {Array} array
 120  * @param {Number} per
 121  */
 122 const arrayChunk = (array, per = 1) => {
 123   const nChunks = Math.ceil(array.length / per);
 124   return Array.from(Array(nChunks), (_, i) => array.slice(i * per, (i + 1) * per));
 125 };
 126
 127
 128 /**
 129  * Be paranoid about blowing the stack when pushing to an array.
 130  * @param {Array} dst
 131  * @param {Array} src
 132  */
 133 const stackSafePush = (dst, src) => {
 134   const jsEngineMaxArguments = 2**16; // Current as of Node 12
 135   arrayChunk(src, jsEngineMaxArguments).forEach((items) => {
 136     Array.prototype.push.apply(dst, items);
 137   });
 138 };
 139
 140
 141 /**
 142  * Limit length of string to keep logs sane
 143  * @param {String} str
 144  * @param {Number} len
 145  * @returns {String}
 146  */
 147 const logTruncate = (str, len) => {
 148   if (typeof str !== 'string' || str.toString().length <= len) {
 149     return str;
 150   }
 151   return str.toString().slice(0, len) + `... (${str.toString().length} bytes)`;
 152 };
 153
 154 module.exports = {
 155   ...common,
 156   arrayChunk,
 157   attemptRetrySeconds,
 158   axiosResponseLogData,
 159   ensureArray,
 160   freezeDeep,
 161   logTruncate,
 162   randomBytesAsync,
 163   stackSafePush,
 164   topicLeaseDefaults,
 165   validHash,
 166 };