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index.js
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index.js
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/**
* CORS middleware for expressjs
* Copyright 2013 by Yuriy Bogdanov <chinsay gmail>
*
* (MIT LICENSE)
* 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.
*/
module.exports = function(options) {
options = options || {};
if (!options.hasOwnProperty('allowCredentials')) {
options.allowCredentials = true;
}
options.methods = options.methods || ['GET', 'POST', 'PUT', 'DELETE', 'PATCH', 'OPTIONS'];
options.headers = options.headers || ['X-Requested-With', 'Content-Type'];
//verify if any origin allowed
if (options.allowedOrigins === '*') options.allowedOrigins = true;
// if string provided as allowed origins, convert to single element array
if (typeof options.allowedOrigins === 'string') options.allowedOrigins = [options.allowedOrigins];
var originMatch = false;
if (options.allowedOrigins === true) {
//match all origins
originMatch = true;
}
else {
// Parse allowed origins list and turn them all into regexps if needed
var allowedOriginsRegexps = [];
var allowedOriginsStrings = options.allowedOrigins.filter(function(origin){
// check if allowed origin starts with http:// or https://
// if not, then we should allow both
var anyHttp = !origin.match(/^https?:\/\//);
// random hash tokens to escape wildcard sequences like "*." and ":*"
var rand = 'WnqkQwirtbRoerjaSnei20ssbqQi',
rand1 = rand + '1',
rand2 = rand + '2';
// to detect if regexp is needed store original origin
var original_origin = origin;
// hide wildcard sequences
origin = origin.replace(/\*\./g, rand1);
origin = origin.replace(/:\*/g, rand2);
if (!anyHttp && (original_origin === origin)) {
//there was strict requirement for protocol
//and no one wildcard sequence so
//regexp is not needed = keep as string
return true;
}
// escape wildcard regexp characters in origin value
origin = escapeRegExp(origin);
// return wildcard sequences back, turning them into reg expressions
origin = origin.replace(new RegExp(rand1, 'g'), '(.*\\.)?');
origin = origin.replace(new RegExp(rand2, 'g'), '(:\\d+)?');
// append http/https expression if we allow both
if (anyHttp) {
origin = '^https?:\/\/' + origin + '$';
}
else {
origin = '^' + origin + '$';
}
allowedOriginsRegexps.push(new RegExp(origin));
return false; //remove from strings
});
if (allowedOriginsStrings.length || allowedOriginsRegexps.length) {
originMatch = function (origin) {
var matched = (allowedOriginsStrings.indexOf(origin) >= 0);
if (!matched) {
// match against all prepared regexp origins
for (i = 0; i < allowedOriginsRegexps.length; ++i) {
if (allowedOriginsRegexps[i].test(origin)) {
matched = true;
break;
}
}
}
return matched;
};
}
}
//prepare ready to use headers if arrays of strings provided in options
options.methods && (options.methods.join) && (options.methods = options.methods.join(', '));
options.headers && (options.headers.join) && (options.headers = options.headers.join(', '));
// express middleware
return !originMatch ?
//match is impossible - always skip CORS processing
function (req, res, next) {
next();
} :
//middleware with verification if there is a match of origin
function(req, res, next) {
var origin = req.get('Origin');
if (!origin || ((originMatch !== true) && !originMatch(origin))) {
//request without Origin header or origin not matched - skip CORS processing
return next();
}
res.set('Access-Control-Allow-Origin', origin);
if (options.methods) {
res.set(
'Access-Control-Allow-Methods',
options.methods === true ? //verify if all methods are allowed
req.get('Access-Control-Request-Method') : //return requested method
options.methods //comma separated list of methods
);
}
if (options.headers) {
res.set(
'Access-Control-Allow-Headers',
options.headers === true ? //verify if all headers are allowed
req.get('Access-Control-Request-Headers') : //return requested header
options.headers //comma separated list of headers
);
}
if (options.maxAge) {
res.set('Access-Control-Max-Age', options.maxAge);
}
if (options.allowCredentials) {
res.set('Access-Control-Allow-Credentials', 'true');
}
if ('OPTIONS' == req.method) {
return res.send(200);
}
next();
};
};
function escapeRegExp(str) {
return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
};