1[RFC6265](https://tools.ietf.org/html/rfc6265) Cookies and CookieJar for Node.js 2 3[](https://nodei.co/npm/tough-cookie/) 4 5[](https://travis-ci.org/salesforce/tough-cookie) 6 7# Synopsis 8 9``` javascript 10var tough = require('tough-cookie'); 11var Cookie = tough.Cookie; 12var cookie = Cookie.parse(header); 13cookie.value = 'somethingdifferent'; 14header = cookie.toString(); 15 16var cookiejar = new tough.CookieJar(); 17cookiejar.setCookie(cookie, 'http://currentdomain.example.com/path', cb); 18// ... 19cookiejar.getCookies('http://example.com/otherpath',function(err,cookies) { 20 res.headers['cookie'] = cookies.join('; '); 21}); 22``` 23 24# Installation 25 26It's _so_ easy! 27 28`npm install tough-cookie` 29 30Why the name? NPM modules `cookie`, `cookies` and `cookiejar` were already taken. 31 32## Version Support 33 34Support for versions of node.js will follow that of the [request](https://www.npmjs.com/package/request) module. 35 36# API 37 38## tough 39 40Functions on the module you get from `require('tough-cookie')`. All can be used as pure functions and don't need to be "bound". 41 42**Note**: prior to 1.0.x, several of these functions took a `strict` parameter. This has since been removed from the API as it was no longer necessary. 43 44### `parseDate(string)` 45 46Parse a cookie date string into a `Date`. Parses according to RFC6265 Section 5.1.1, not `Date.parse()`. 47 48### `formatDate(date)` 49 50Format a Date into a RFC1123 string (the RFC6265-recommended format). 51 52### `canonicalDomain(str)` 53 54Transforms a domain-name into a canonical domain-name. The canonical domain-name is a trimmed, lowercased, stripped-of-leading-dot and optionally punycode-encoded domain-name (Section 5.1.2 of RFC6265). For the most part, this function is idempotent (can be run again on its output without ill effects). 55 56### `domainMatch(str,domStr[,canonicalize=true])` 57 58Answers "does this real domain match the domain in a cookie?". The `str` is the "current" domain-name and the `domStr` is the "cookie" domain-name. Matches according to RFC6265 Section 5.1.3, but it helps to think of it as a "suffix match". 59 60The `canonicalize` parameter will run the other two parameters through `canonicalDomain` or not. 61 62### `defaultPath(path)` 63 64Given a current request/response path, gives the Path apropriate for storing in a cookie. This is basically the "directory" of a "file" in the path, but is specified by Section 5.1.4 of the RFC. 65 66The `path` parameter MUST be _only_ the pathname part of a URI (i.e. excludes the hostname, query, fragment, etc.). This is the `.pathname` property of node's `uri.parse()` output. 67 68### `pathMatch(reqPath,cookiePath)` 69 70Answers "does the request-path path-match a given cookie-path?" as per RFC6265 Section 5.1.4. Returns a boolean. 71 72This is essentially a prefix-match where `cookiePath` is a prefix of `reqPath`. 73 74### `parse(cookieString[, options])` 75 76alias for `Cookie.parse(cookieString[, options])` 77 78### `fromJSON(string)` 79 80alias for `Cookie.fromJSON(string)` 81 82### `getPublicSuffix(hostname)` 83 84Returns the public suffix of this hostname. The public suffix is the shortest domain-name upon which a cookie can be set. Returns `null` if the hostname cannot have cookies set for it. 85 86For example: `www.example.com` and `www.subdomain.example.com` both have public suffix `example.com`. 87 88For further information, see http://publicsuffix.org/. This module derives its list from that site. This call is currently a wrapper around [`psl`](https://www.npmjs.com/package/psl)'s [get() method](https://www.npmjs.com/package/psl#pslgetdomain). 89 90### `cookieCompare(a,b)` 91 92For use with `.sort()`, sorts a list of cookies into the recommended order given in the RFC (Section 5.4 step 2). The sort algorithm is, in order of precedence: 93 94* Longest `.path` 95* oldest `.creation` (which has a 1ms precision, same as `Date`) 96* lowest `.creationIndex` (to get beyond the 1ms precision) 97 98``` javascript 99var cookies = [ /* unsorted array of Cookie objects */ ]; 100cookies = cookies.sort(cookieCompare); 101``` 102 103**Note**: Since JavaScript's `Date` is limited to a 1ms precision, cookies within the same milisecond are entirely possible. This is especially true when using the `now` option to `.setCookie()`. The `.creationIndex` property is a per-process global counter, assigned during construction with `new Cookie()`. This preserves the spirit of the RFC sorting: older cookies go first. This works great for `MemoryCookieStore`, since `Set-Cookie` headers are parsed in order, but may not be so great for distributed systems. Sophisticated `Store`s may wish to set this to some other _logical clock_ such that if cookies A and B are created in the same millisecond, but cookie A is created before cookie B, then `A.creationIndex < B.creationIndex`. If you want to alter the global counter, which you probably _shouldn't_ do, it's stored in `Cookie.cookiesCreated`. 104 105### `permuteDomain(domain)` 106 107Generates a list of all possible domains that `domainMatch()` the parameter. May be handy for implementing cookie stores. 108 109### `permutePath(path)` 110 111Generates a list of all possible paths that `pathMatch()` the parameter. May be handy for implementing cookie stores. 112 113 114## Cookie 115 116Exported via `tough.Cookie`. 117 118### `Cookie.parse(cookieString[, options])` 119 120Parses a single Cookie or Set-Cookie HTTP header into a `Cookie` object. Returns `undefined` if the string can't be parsed. 121 122The options parameter is not required and currently has only one property: 123 124 * _loose_ - boolean - if `true` enable parsing of key-less cookies like `=abc` and `=`, which are not RFC-compliant. 125 126If options is not an object, it is ignored, which means you can use `Array#map` with it. 127 128Here's how to process the Set-Cookie header(s) on a node HTTP/HTTPS response: 129 130``` javascript 131if (res.headers['set-cookie'] instanceof Array) 132 cookies = res.headers['set-cookie'].map(Cookie.parse); 133else 134 cookies = [Cookie.parse(res.headers['set-cookie'])]; 135``` 136 137_Note:_ in version 2.3.3, tough-cookie limited the number of spaces before the `=` to 256 characters. This limitation has since been removed. 138See [Issue 92](https://github.com/salesforce/tough-cookie/issues/92) 139 140### Properties 141 142Cookie object properties: 143 144 * _key_ - string - the name or key of the cookie (default "") 145 * _value_ - string - the value of the cookie (default "") 146 * _expires_ - `Date` - if set, the `Expires=` attribute of the cookie (defaults to the string `"Infinity"`). See `setExpires()` 147 * _maxAge_ - seconds - if set, the `Max-Age=` attribute _in seconds_ of the cookie. May also be set to strings `"Infinity"` and `"-Infinity"` for non-expiry and immediate-expiry, respectively. See `setMaxAge()` 148 * _domain_ - string - the `Domain=` attribute of the cookie 149 * _path_ - string - the `Path=` of the cookie 150 * _secure_ - boolean - the `Secure` cookie flag 151 * _httpOnly_ - boolean - the `HttpOnly` cookie flag 152 * _extensions_ - `Array` - any unrecognized cookie attributes as strings (even if equal-signs inside) 153 * _creation_ - `Date` - when this cookie was constructed 154 * _creationIndex_ - number - set at construction, used to provide greater sort precision (please see `cookieCompare(a,b)` for a full explanation) 155 156After a cookie has been passed through `CookieJar.setCookie()` it will have the following additional attributes: 157 158 * _hostOnly_ - boolean - is this a host-only cookie (i.e. no Domain field was set, but was instead implied) 159 * _pathIsDefault_ - boolean - if true, there was no Path field on the cookie and `defaultPath()` was used to derive one. 160 * _creation_ - `Date` - **modified** from construction to when the cookie was added to the jar 161 * _lastAccessed_ - `Date` - last time the cookie got accessed. Will affect cookie cleaning once implemented. Using `cookiejar.getCookies(...)` will update this attribute. 162 163### `Cookie([{properties}])` 164 165Receives an options object that can contain any of the above Cookie properties, uses the default for unspecified properties. 166 167### `.toString()` 168 169encode to a Set-Cookie header value. The Expires cookie field is set using `formatDate()`, but is omitted entirely if `.expires` is `Infinity`. 170 171### `.cookieString()` 172 173encode to a Cookie header value (i.e. the `.key` and `.value` properties joined with '='). 174 175### `.setExpires(String)` 176 177sets the expiry based on a date-string passed through `parseDate()`. If parseDate returns `null` (i.e. can't parse this date string), `.expires` is set to `"Infinity"` (a string) is set. 178 179### `.setMaxAge(number)` 180 181sets the maxAge in seconds. Coerces `-Infinity` to `"-Infinity"` and `Infinity` to `"Infinity"` so it JSON serializes correctly. 182 183### `.expiryTime([now=Date.now()])` 184 185### `.expiryDate([now=Date.now()])` 186 187expiryTime() Computes the absolute unix-epoch milliseconds that this cookie expires. expiryDate() works similarly, except it returns a `Date` object. Note that in both cases the `now` parameter should be milliseconds. 188 189Max-Age takes precedence over Expires (as per the RFC). The `.creation` attribute -- or, by default, the `now` parameter -- is used to offset the `.maxAge` attribute. 190 191If Expires (`.expires`) is set, that's returned. 192 193Otherwise, `expiryTime()` returns `Infinity` and `expiryDate()` returns a `Date` object for "Tue, 19 Jan 2038 03:14:07 GMT" (latest date that can be expressed by a 32-bit `time_t`; the common limit for most user-agents). 194 195### `.TTL([now=Date.now()])` 196 197compute the TTL relative to `now` (milliseconds). The same precedence rules as for `expiryTime`/`expiryDate` apply. 198 199The "number" `Infinity` is returned for cookies without an explicit expiry and `0` is returned if the cookie is expired. Otherwise a time-to-live in milliseconds is returned. 200 201### `.canonicalizedDoman()` 202 203### `.cdomain()` 204 205return the canonicalized `.domain` field. This is lower-cased and punycode (RFC3490) encoded if the domain has any non-ASCII characters. 206 207### `.toJSON()` 208 209For convenience in using `JSON.serialize(cookie)`. Returns a plain-old `Object` that can be JSON-serialized. 210 211Any `Date` properties (i.e., `.expires`, `.creation`, and `.lastAccessed`) are exported in ISO format (`.toISOString()`). 212 213**NOTE**: Custom `Cookie` properties will be discarded. In tough-cookie 1.x, since there was no `.toJSON` method explicitly defined, all enumerable properties were captured. If you want a property to be serialized, add the property name to the `Cookie.serializableProperties` Array. 214 215### `Cookie.fromJSON(strOrObj)` 216 217Does the reverse of `cookie.toJSON()`. If passed a string, will `JSON.parse()` that first. 218 219Any `Date` properties (i.e., `.expires`, `.creation`, and `.lastAccessed`) are parsed via `Date.parse()`, not the tough-cookie `parseDate`, since it's JavaScript/JSON-y timestamps being handled at this layer. 220 221Returns `null` upon JSON parsing error. 222 223### `.clone()` 224 225Does a deep clone of this cookie, exactly implemented as `Cookie.fromJSON(cookie.toJSON())`. 226 227### `.validate()` 228 229Status: *IN PROGRESS*. Works for a few things, but is by no means comprehensive. 230 231validates cookie attributes for semantic correctness. Useful for "lint" checking any Set-Cookie headers you generate. For now, it returns a boolean, but eventually could return a reason string -- you can future-proof with this construct: 232 233``` javascript 234if (cookie.validate() === true) { 235 // it's tasty 236} else { 237 // yuck! 238} 239``` 240 241 242## CookieJar 243 244Exported via `tough.CookieJar`. 245 246### `CookieJar([store],[options])` 247 248Simply use `new CookieJar()`. If you'd like to use a custom store, pass that to the constructor otherwise a `MemoryCookieStore` will be created and used. 249 250The `options` object can be omitted and can have the following properties: 251 252 * _rejectPublicSuffixes_ - boolean - default `true` - reject cookies with domains like "com" and "co.uk" 253 * _looseMode_ - boolean - default `false` - accept malformed cookies like `bar` and `=bar`, which have an implied empty name. 254 This is not in the standard, but is used sometimes on the web and is accepted by (most) browsers. 255 256Since eventually this module would like to support database/remote/etc. CookieJars, continuation passing style is used for CookieJar methods. 257 258### `.setCookie(cookieOrString, currentUrl, [{options},] cb(err,cookie))` 259 260Attempt to set the cookie in the cookie jar. If the operation fails, an error will be given to the callback `cb`, otherwise the cookie is passed through. The cookie will have updated `.creation`, `.lastAccessed` and `.hostOnly` properties. 261 262The `options` object can be omitted and can have the following properties: 263 264 * _http_ - boolean - default `true` - indicates if this is an HTTP or non-HTTP API. Affects HttpOnly cookies. 265 * _secure_ - boolean - autodetect from url - indicates if this is a "Secure" API. If the currentUrl starts with `https:` or `wss:` then this is defaulted to `true`, otherwise `false`. 266 * _now_ - Date - default `new Date()` - what to use for the creation/access time of cookies 267 * _ignoreError_ - boolean - default `false` - silently ignore things like parse errors and invalid domains. `Store` errors aren't ignored by this option. 268 269As per the RFC, the `.hostOnly` property is set if there was no "Domain=" parameter in the cookie string (or `.domain` was null on the Cookie object). The `.domain` property is set to the fully-qualified hostname of `currentUrl` in this case. Matching this cookie requires an exact hostname match (not a `domainMatch` as per usual). 270 271### `.setCookieSync(cookieOrString, currentUrl, [{options}])` 272 273Synchronous version of `setCookie`; only works with synchronous stores (e.g. the default `MemoryCookieStore`). 274 275### `.getCookies(currentUrl, [{options},] cb(err,cookies))` 276 277Retrieve the list of cookies that can be sent in a Cookie header for the current url. 278 279If an error is encountered, that's passed as `err` to the callback, otherwise an `Array` of `Cookie` objects is passed. The array is sorted with `cookieCompare()` unless the `{sort:false}` option is given. 280 281The `options` object can be omitted and can have the following properties: 282 283 * _http_ - boolean - default `true` - indicates if this is an HTTP or non-HTTP API. Affects HttpOnly cookies. 284 * _secure_ - boolean - autodetect from url - indicates if this is a "Secure" API. If the currentUrl starts with `https:` or `wss:` then this is defaulted to `true`, otherwise `false`. 285 * _now_ - Date - default `new Date()` - what to use for the creation/access time of cookies 286 * _expire_ - boolean - default `true` - perform expiry-time checking of cookies and asynchronously remove expired cookies from the store. Using `false` will return expired cookies and **not** remove them from the store (which is useful for replaying Set-Cookie headers, potentially). 287 * _allPaths_ - boolean - default `false` - if `true`, do not scope cookies by path. The default uses RFC-compliant path scoping. **Note**: may not be supported by the underlying store (the default `MemoryCookieStore` supports it). 288 289The `.lastAccessed` property of the returned cookies will have been updated. 290 291### `.getCookiesSync(currentUrl, [{options}])` 292 293Synchronous version of `getCookies`; only works with synchronous stores (e.g. the default `MemoryCookieStore`). 294 295### `.getCookieString(...)` 296 297Accepts the same options as `.getCookies()` but passes a string suitable for a Cookie header rather than an array to the callback. Simply maps the `Cookie` array via `.cookieString()`. 298 299### `.getCookieStringSync(...)` 300 301Synchronous version of `getCookieString`; only works with synchronous stores (e.g. the default `MemoryCookieStore`). 302 303### `.getSetCookieStrings(...)` 304 305Returns an array of strings suitable for **Set-Cookie** headers. Accepts the same options as `.getCookies()`. Simply maps the cookie array via `.toString()`. 306 307### `.getSetCookieStringsSync(...)` 308 309Synchronous version of `getSetCookieStrings`; only works with synchronous stores (e.g. the default `MemoryCookieStore`). 310 311### `.serialize(cb(err,serializedObject))` 312 313Serialize the Jar if the underlying store supports `.getAllCookies`. 314 315**NOTE**: Custom `Cookie` properties will be discarded. If you want a property to be serialized, add the property name to the `Cookie.serializableProperties` Array. 316 317See [Serialization Format]. 318 319### `.serializeSync()` 320 321Sync version of .serialize 322 323### `.toJSON()` 324 325Alias of .serializeSync() for the convenience of `JSON.stringify(cookiejar)`. 326 327### `CookieJar.deserialize(serialized, [store], cb(err,object))` 328 329A new Jar is created and the serialized Cookies are added to the underlying store. Each `Cookie` is added via `store.putCookie` in the order in which they appear in the serialization. 330 331The `store` argument is optional, but should be an instance of `Store`. By default, a new instance of `MemoryCookieStore` is created. 332 333As a convenience, if `serialized` is a string, it is passed through `JSON.parse` first. If that throws an error, this is passed to the callback. 334 335### `CookieJar.deserializeSync(serialized, [store])` 336 337Sync version of `.deserialize`. _Note_ that the `store` must be synchronous for this to work. 338 339### `CookieJar.fromJSON(string)` 340 341Alias of `.deserializeSync` to provide consistency with `Cookie.fromJSON()`. 342 343### `.clone([store,]cb(err,newJar))` 344 345Produces a deep clone of this jar. Modifications to the original won't affect the clone, and vice versa. 346 347The `store` argument is optional, but should be an instance of `Store`. By default, a new instance of `MemoryCookieStore` is created. Transferring between store types is supported so long as the source implements `.getAllCookies()` and the destination implements `.putCookie()`. 348 349### `.cloneSync([store])` 350 351Synchronous version of `.clone`, returning a new `CookieJar` instance. 352 353The `store` argument is optional, but must be a _synchronous_ `Store` instance if specified. If not passed, a new instance of `MemoryCookieStore` is used. 354 355The _source_ and _destination_ must both be synchronous `Store`s. If one or both stores are asynchronous, use `.clone` instead. Recall that `MemoryCookieStore` supports both synchronous and asynchronous API calls. 356 357## Store 358 359Base class for CookieJar stores. Available as `tough.Store`. 360 361## Store API 362 363The storage model for each `CookieJar` instance can be replaced with a custom implementation. The default is `MemoryCookieStore` which can be found in the `lib/memstore.js` file. The API uses continuation-passing-style to allow for asynchronous stores. 364 365Stores should inherit from the base `Store` class, which is available as `require('tough-cookie').Store`. 366 367Stores are asynchronous by default, but if `store.synchronous` is set to `true`, then the `*Sync` methods on the of the containing `CookieJar` can be used (however, the continuation-passing style 368 369All `domain` parameters will have been normalized before calling. 370 371The Cookie store must have all of the following methods. 372 373### `store.findCookie(domain, path, key, cb(err,cookie))` 374 375Retrieve a cookie with the given domain, path and key (a.k.a. name). The RFC maintains that exactly one of these cookies should exist in a store. If the store is using versioning, this means that the latest/newest such cookie should be returned. 376 377Callback takes an error and the resulting `Cookie` object. If no cookie is found then `null` MUST be passed instead (i.e. not an error). 378 379### `store.findCookies(domain, path, cb(err,cookies))` 380 381Locates cookies matching the given domain and path. This is most often called in the context of `cookiejar.getCookies()` above. 382 383If no cookies are found, the callback MUST be passed an empty array. 384 385The resulting list will be checked for applicability to the current request according to the RFC (domain-match, path-match, http-only-flag, secure-flag, expiry, etc.), so it's OK to use an optimistic search algorithm when implementing this method. However, the search algorithm used SHOULD try to find cookies that `domainMatch()` the domain and `pathMatch()` the path in order to limit the amount of checking that needs to be done. 386 387As of version 0.9.12, the `allPaths` option to `cookiejar.getCookies()` above will cause the path here to be `null`. If the path is `null`, path-matching MUST NOT be performed (i.e. domain-matching only). 388 389### `store.putCookie(cookie, cb(err))` 390 391Adds a new cookie to the store. The implementation SHOULD replace any existing cookie with the same `.domain`, `.path`, and `.key` properties -- depending on the nature of the implementation, it's possible that between the call to `fetchCookie` and `putCookie` that a duplicate `putCookie` can occur. 392 393The `cookie` object MUST NOT be modified; the caller will have already updated the `.creation` and `.lastAccessed` properties. 394 395Pass an error if the cookie cannot be stored. 396 397### `store.updateCookie(oldCookie, newCookie, cb(err))` 398 399Update an existing cookie. The implementation MUST update the `.value` for a cookie with the same `domain`, `.path` and `.key`. The implementation SHOULD check that the old value in the store is equivalent to `oldCookie` - how the conflict is resolved is up to the store. 400 401The `.lastAccessed` property will always be different between the two objects (to the precision possible via JavaScript's clock). Both `.creation` and `.creationIndex` are guaranteed to be the same. Stores MAY ignore or defer the `.lastAccessed` change at the cost of affecting how cookies are selected for automatic deletion (e.g., least-recently-used, which is up to the store to implement). 402 403Stores may wish to optimize changing the `.value` of the cookie in the store versus storing a new cookie. If the implementation doesn't define this method a stub that calls `putCookie(newCookie,cb)` will be added to the store object. 404 405The `newCookie` and `oldCookie` objects MUST NOT be modified. 406 407Pass an error if the newCookie cannot be stored. 408 409### `store.removeCookie(domain, path, key, cb(err))` 410 411Remove a cookie from the store (see notes on `findCookie` about the uniqueness constraint). 412 413The implementation MUST NOT pass an error if the cookie doesn't exist; only pass an error due to the failure to remove an existing cookie. 414 415### `store.removeCookies(domain, path, cb(err))` 416 417Removes matching cookies from the store. The `path` parameter is optional, and if missing means all paths in a domain should be removed. 418 419Pass an error ONLY if removing any existing cookies failed. 420 421### `store.getAllCookies(cb(err, cookies))` 422 423Produces an `Array` of all cookies during `jar.serialize()`. The items in the array can be true `Cookie` objects or generic `Object`s with the [Serialization Format] data structure. 424 425Cookies SHOULD be returned in creation order to preserve sorting via `compareCookies()`. For reference, `MemoryCookieStore` will sort by `.creationIndex` since it uses true `Cookie` objects internally. If you don't return the cookies in creation order, they'll still be sorted by creation time, but this only has a precision of 1ms. See `compareCookies` for more detail. 426 427Pass an error if retrieval fails. 428 429## MemoryCookieStore 430 431Inherits from `Store`. 432 433A just-in-memory CookieJar synchronous store implementation, used by default. Despite being a synchronous implementation, it's usable with both the synchronous and asynchronous forms of the `CookieJar` API. 434 435## Community Cookie Stores 436 437These are some Store implementations authored and maintained by the community. They aren't official and we don't vouch for them but you may be interested to have a look: 438 439- [`db-cookie-store`](https://github.com/JSBizon/db-cookie-store): SQL including SQLite-based databases 440- [`file-cookie-store`](https://github.com/JSBizon/file-cookie-store): Netscape cookie file format on disk 441- [`redis-cookie-store`](https://github.com/benkroeger/redis-cookie-store): Redis 442- [`tough-cookie-filestore`](https://github.com/mitsuru/tough-cookie-filestore): JSON on disk 443- [`tough-cookie-web-storage-store`](https://github.com/exponentjs/tough-cookie-web-storage-store): DOM localStorage and sessionStorage 444 445 446# Serialization Format 447 448**NOTE**: if you want to have custom `Cookie` properties serialized, add the property name to `Cookie.serializableProperties`. 449 450```js 451 { 452 // The version of tough-cookie that serialized this jar. 453 version: 'tough-cookie@1.x.y', 454 455 // add the store type, to make humans happy: 456 storeType: 'MemoryCookieStore', 457 458 // CookieJar configuration: 459 rejectPublicSuffixes: true, 460 // ... future items go here 461 462 // Gets filled from jar.store.getAllCookies(): 463 cookies: [ 464 { 465 key: 'string', 466 value: 'string', 467 // ... 468 /* other Cookie.serializableProperties go here */ 469 } 470 ] 471 } 472``` 473 474# Copyright and License 475 476(tl;dr: BSD-3-Clause with some MPL/2.0) 477 478```text 479 Copyright (c) 2015, Salesforce.com, Inc. 480 All rights reserved. 481 482 Redistribution and use in source and binary forms, with or without 483 modification, are permitted provided that the following conditions are met: 484 485 1. Redistributions of source code must retain the above copyright notice, 486 this list of conditions and the following disclaimer. 487 488 2. Redistributions in binary form must reproduce the above copyright notice, 489 this list of conditions and the following disclaimer in the documentation 490 and/or other materials provided with the distribution. 491 492 3. Neither the name of Salesforce.com nor the names of its contributors may 493 be used to endorse or promote products derived from this software without 494 specific prior written permission. 495 496 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 497 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 498 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 499 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 500 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 501 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 502 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 503 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 504 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 505 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 506 POSSIBILITY OF SUCH DAMAGE. 507``` 508