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Coverage for /Users/yunong/workspace/node-restify/lib/plugins/throttle.js : 96%
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 | // Copyright 2012 Mark Cavage <mcavage@gmail.com> All rights reserved. var sprintf = require('util').format; var assert = require('assert-plus'); var LRU = require('lru-cache'); var errors = require('../errors'); ///--- Globals var TooManyRequestsError = errors.TooManyRequestsError; var MESSAGE = 'You have exceeded your request rate of %s r/s.'; ///--- Helpers function xor() { var x = false; for (var i = 0; i < arguments.length; i++) { if (arguments[i] && !x) x = true; else if (arguments[i] && x) return (false); } return (x); } ///--- Internal Class (TokenBucket) /** * An implementation of the Token Bucket algorithm. * * Basically, in network throttling, there are two "mainstream" * algorithms for throttling requests, Token Bucket and Leaky Bucket. * For restify, I went with Token Bucket. For a good description of the * algorithm, see: http://en.wikipedia.org/wiki/Token_bucket * * In the options object, you pass in the total tokens and the fill rate. * Practically speaking, this means "allow `fill rate` requests/second, * with bursts up to `total tokens`". Note that the bucket is initialized * to full. * * Also, in googling, I came across a concise python implementation, so this * is just a port of that. Thanks http://code.activestate.com/recipes/511490 ! * * @param {Object} options contains the parameters: * - {Number} capacity the maximum burst. * - {Number} fillRate the rate to refill tokens. */ function TokenBucket(options) { assert.object(options, 'options'); assert.number(options.capacity, 'options.capacity'); assert.number(options.fillRate, 'options.fillRate'); this.tokens = this.capacity = options.capacity; this.fillRate = options.fillRate; this.time = Date.now(); } /** * Consume N tokens from the bucket. * * If there is not capacity, the tokens are not pulled from the bucket. * * @param {Number} tokens the number of tokens to pull out. * @return {Boolean} true if capacity, false otherwise. */ TokenBucket.prototype.consume = function consume(tokens) { if (tokens <= this._fill()) { this.tokens -= tokens; return (true); } return (false); }; /** * Fills the bucket with more tokens. * * Rather than do some whacky setTimeout() deal, we just approximate refilling * the bucket by tracking elapsed time from the last time we touched the bucket. * * Simply, we set the bucket size to min(totalTokens, * current + (fillRate * elapsed time)). * * @return {Number} the current number of tokens in the bucket. */ TokenBucket.prototype._fill = function _fill() { var now = Date.now(); if (now < this.time) // reset account for clock drift (like DST) this.time = now - 1000; if (this.tokens < this.capacity) { var delta = this.fillRate * ((now - this.time) / 1000); this.tokens = Math.min(this.capacity, this.tokens + delta); } this.time = now; return (this.tokens); }; ///--- Internal Class (TokenTable) // Just a wrapper over LRU that supports put/get to store token -> bucket // mappings function TokenTable(options) { assert.object(options, 'options'); this.table = new LRU(options.size || 10000); } TokenTable.prototype.put = function put(key, value) { this.table.set(key, value); }; TokenTable.prototype.get = function get(key) { return (this.table.get(key)); }; ///--- Exported API /** * Creates an API rate limiter that can be plugged into the standard * restify request handling pipeline. * * This throttle gives you three options on which to throttle: * username, IP address and 'X-Forwarded-For'. IP/XFF is a /32 match, * so keep that in mind if using it. Username takes the user specified * on req.username (which gets automagically set for supported Authorization * types; otherwise set it yourself with a filter that runs before this). * * In both cases, you can set a `burst` and a `rate` (in requests/seconds), * as an integer/float. Those really translate to the `TokenBucket` * algorithm, so read up on that (or see the comments above...). * * In either case, the top level options burst/rate set a blanket throttling * rate, and then you can pass in an `overrides` object with rates for * specific users/IPs. You should use overrides sparingly, as we make a new * TokenBucket to track each. * * On the `options` object ip and username are treated as an XOR. * * An example options object with overrides: * * { * burst: 10, // Max 10 concurrent requests (if tokens) * rate: 0.5, // Steady state: 1 request / 2 seconds * ip: true, // throttle per IP * overrides: { * '192.168.1.1': { * burst: 0, * rate: 0 // unlimited * } * } * * * @param {Object} options required options with: * - {Number} burst (required). * - {Number} rate (required). * - {Boolean} ip (optional). * - {Boolean} username (optional). * - {Boolean} xff (optional). * - {Object} overrides (optional). * - {Object} tokensTable: a storage engine this plugin will * use to store throttling keys -> bucket mappings. * If you don't specify this, the default is to * use an in-memory O(1) LRU, with 10k distinct * keys. Any implementation just needs to support * put/get. * - {Number} maxKeys: If using the default implementation, * you can specify how large you want the table to * be. Default is 10000. * @return {Function} of type f(req, res, next) to be plugged into a route. * @throws {TypeError} on bad input. */ function throttle(options) { assert.object(options, 'options'); assert.number(options.burst, 'options.burst'); assert.number(options.rate, 'options.rate'); if (!xor(options.ip, options.xff, options.username)) throw new Error('(ip ^ username ^ xff)'); var table = options.tokensTable || new TokenTable({size: options.maxKeys}); function rateLimit(req, res, next) { var attr; var burst = options.burst; var rate = options.rate; if (options.ip) { attr = req.connection.remoteAddress; } else if (options.xff) { attr = req.headers['x-forwarded-for']; } else if (options.username) { attr = req.username; } else { req.log.warn({config: options}, 'Invalid throttle configuration'); return (next()); } // Before bothering with overrides, see if this request // even matches if (!attr) return (next()); // Check the overrides if (options.overrides && options.overrides[attr] && options.overrides[attr].burst !== undefined && options.overrides[attr].rate !== undefined) { burst = options.overrides[attr].burst; rate = options.overrides[attr].rate; } if (!rate || !burst) return (next()); var bucket = table.get(attr); if (!bucket) { bucket = new TokenBucket({ capacity: burst, fillRate: rate }); table.put(attr, bucket); } req.log.trace('Throttle(%s): num_tokens= %d', attr, bucket.tokens); if (!bucket.consume(1)) { req.log.info({ address: req.connection.remoteAddress || '?', method: req.method, url: req.url, user: req.username || '?' }, 'Throttling'); var msg = sprintf(MESSAGE, rate); return (next(new TooManyRequestsError(msg))); } return (next()); } return (rateLimit); } module.exports = throttle; |