valid-data-url's Introduction

Detect if a string is a data URL

Based on Brian Grinstead's solution https://gist.github.com/bgrins/6194623. Special thanks to Jamie Davis for helping to fix ReDoS exploit.

Syntax

The "data" URL scheme is described here RFC2397

dataurl    := "data:" [ mediatype ] [ ";base64" ] "," data
mediatype  := [ type "/" subtype ] *( ";" parameter )
data       := *urlchar
parameter  := attribute "=" value

where urlchar is imported from RFC2396, and type, subtype, attribute and value are the corresponding tokens from RFC2045, represented using URL escaped encoding of RFC2396 as necessary.

Attribute values in RFC2045 are allowed to be either represented as tokens or as quoted strings. However, within a data URL, the quoted-string representation would be awkward, since the quote mark is itself not a valid urlchar. For this reason, parameter values should use the URL Escaped encoding instead of quoted string if the parameter values contain any tspecial.

The ;base64 extension is distinguishable from a content-type parameter by the fact that it doesn't have a following = sign.

Install

npm install valid-data-url

Example

'use strict';

var validDataUrl = require('valid-data-url');
var isValid = validDataUrl('data:text/plain;base64,SGVsbG8sIFdvcmxkIQ%3D%3D'); // true

People

The original author is Brian Grinstead

Contributors

Licence

The MIT License (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

valid-data-url's People