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 got response fields.
  65  * @param {*} res
  66  * @returns
  67  */
  68 const gotResponseLogData = (res) => {
  69   const data = common.pick(res, [
  70     'statusCode',
  71     'statusMessage',
  72     'headers',
  73     'body',
  74     'error',
  75   ]);
  76   if (typeof res.body === 'string') {
  77     data.body = logTruncate(data.body, 100);
  78   } else if (res.body instanceof Buffer) {
  79     data.body = `<Buffer ${res.body.byteLength} bytes>`;
  80   }
  81   if (res?.timings?.phases?.total) {
  82     data.elapsedTimeMs = res.timings.phases.total;
  83   }
  84   if (res?.redirectUrls?.length) {
  85     data.redirectUrls = res.redirectUrls;
  86   }
  87   if (res?.retryCount) {
  88     data.retryCount = res.retryCount;
  89   }
  90   return data;
  91 };
  92
  93
  94 /**
  95  * Fallback values, if not configured.
  96  * @returns {Object}
  97  */
  98 const topicLeaseDefaults = () => {
  99   return Object.freeze({
 100     leaseSecondsPreferred: 86400 * 10,
 101     leaseSecondsMin: 86400 * 1,
 102     leaseSecondsMax: 86400 * 365,
 103   });
 104 };
 105
 106
 107 /**
 108  * Pick from a range, constrained, with some fuzziness.
 109  * @param {Number} attempt
 110  * @param {Number[]} delays
 111  * @param {Number} jitter
 112  * @returns {Number}
 113  */
 114 const attemptRetrySeconds = (attempt, retryBackoffSeconds = [60, 120, 360, 1440, 7200, 43200, 86400], jitter = 0.618) => {
 115   const maxAttempt = retryBackoffSeconds.length - 1;
 116   if (typeof attempt !== 'number' || attempt < 0) {
 117     attempt = 0;
 118   } else if (attempt > maxAttempt) {
 119     attempt = maxAttempt;
 120   }
 121   // eslint-disable-next-line security/detect-object-injection
 122   let seconds = retryBackoffSeconds[attempt];
 123   seconds += Math.floor(Math.random() * seconds * jitter);
 124   return seconds;
 125 };
 126
 127
 128 /**
 129  * Return array items split as an array of arrays of no more than per items each.
 130  * @param {Array} array
 131  * @param {Number} per
 132  */
 133 const arrayChunk = (array, per = 1) => {
 134   const nChunks = Math.ceil(array.length / per);
 135   return Array.from(Array(nChunks), (_, i) => array.slice(i * per, (i + 1) * per));
 136 };
 137
 138
 139 /**
 140  * Be paranoid about blowing the stack when pushing to an array.
 141  * @param {Array} dst
 142  * @param {Array} src
 143  */
 144 const stackSafePush = (dst, src) => {
 145   const jsEngineMaxArguments = 2**16; // Current as of Node 12
 146   arrayChunk(src, jsEngineMaxArguments).forEach((items) => {
 147     Array.prototype.push.apply(dst, items);
 148   });
 149 };
 150
 151
 152 /**
 153  * Limit length of string to keep logs sane
 154  * @param {String} str
 155  * @param {Number} len
 156  * @returns {String}
 157  */
 158 const logTruncate = (str, len) => {
 159   if (typeof str !== 'string' || str.toString().length <= len) {
 160     return str;
 161   }
 162   return str.toString().slice(0, len) + `... (${str.toString().length} bytes)`;
 163 };
 164
 165 module.exports = {
 166   ...common,
 167   arrayChunk,
 168   attemptRetrySeconds,
 169   gotResponseLogData,
 170   ensureArray,
 171   freezeDeep,
 172   logTruncate,
 173   randomBytesAsync,
 174   stackSafePush,
 175   topicLeaseDefaults,
 176   validHash,
 177 };