# resolve-path
[![NPM Version][npm-image]][npm-url]
[![NPM Downloads][downloads-image]][downloads-url]
[![Node.js Version][node-image]][node-url]
[![Linux Build][travis-image]][travis-url]
[![Windows Build][appveyor-image]][appveyor-url]
[![Test Coverage][coveralls-image]][coveralls-url]
Resolve a relative path against a root path with validation.
This module would protect against commons attacks like `GET /../file.js`
which reaches outside the root folder.
## Installation
This is a [Node.js](https://nodejs.org/en/) module available through the
[npm registry](https://www.npmjs.com/). Installation is done using the
[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally):
```sh
$ npm install resolve-path
```
## API
```
var resolvePath = require('resolve-path')
```
### resolvePath(relativePath)
Resolve a relative path against `process.cwd()` (the process's current working
directory) and return an absolute path. *This will throw* if the resulting resolution
seems malicious. The following are malicious:
- The relative path is an absolute path
- The relative path contains a NULL byte
- The relative path resolves to a path outside of `process.cwd()`
- The relative path traverses above `process.cwd()` and back down
### resolvePath(rootPath, relativePath)
Resolve a relative path against the provided root path and return an absolute path.
*This will throw* if the resulting resolution seems malicious. The following are
malicious:
- The relative path is an absolute path
- The relative path contains a NULL byte
- The relative path resolves to a path outside of the root path
- The relative path traverses above the root and back down
## Example
### Safely resolve paths in a public directory
```js
var http = require('http')
var parseUrl = require('parseurl')
var path = require('path')
var resolvePath = require('resolve-path')
// the public directory
var publicDir = path.join(__dirname, 'public')
// the server
var server = http.createServer(function onRequest (req, res) {
try {
// get the pathname from the URL (decoded)
var pathname = decodeURIComponent(parseUrl(req).pathname)
if (!pathname) {
res.statusCode = 400
res.end('path required')
return
}
// remove leading slash
var filename = pathname.substr(1)
// resolve the full path
var fullpath = resolvePath(publicDir, filename)
// echo the resolved path
res.statusCode = 200
res.end('resolved to ' + fullpath)
} catch (err) {
res.statusCode = err.status || 500
res.end(err.message)
}
})
server.listen(3000)
```
## License
[MIT](LICENSE)
[npm-image]: https://img.shields.io/npm/v/resolve-path.svg
[npm-url]: https://npmjs.org/package/resolve-path
[node-image]: https://img.shields.io/node/v/resolve-path.svg
[node-url]: http://nodejs.org/download/
[travis-image]: https://img.shields.io/travis/pillarjs/resolve-path/master.svg?label=linux
[travis-url]: https://travis-ci.org/pillarjs/resolve-path
[appveyor-image]: https://img.shields.io/appveyor/ci/dougwilson/resolve-path/master.svg?label=windows
[appveyor-url]: https://ci.appveyor.com/project/dougwilson/resolve-path
[coveralls-image]: https://img.shields.io/coveralls/pillarjs/resolve-path/master.svg
[coveralls-url]: https://coveralls.io/r/pillarjs/resolve-path?branch=master
[downloads-image]: https://img.shields.io/npm/dm/resolve-path.svg
[downloads-url]: https://npmjs.org/package/resolve-path