windows azure : set blob CORS properties using NodeJS - node.js

Question

REST API has been released in february to set blob CORS property, but this hasn't been implemented for NodeJS yet.
Since I need this feature, I tried to implement it in a module for my azure website running NodeJS.
Based on REST API documentation to change CORS properties and to generate authentification key, on this implementation of authentification key generation using NodeJS, I tried to follow the accepted answer from this post, but it didn't work for me.
Here is what I've got in setcrosproperties.js :
var crypto = require('crypto');
var request = require('request');
exports.setCors = function (MY_ACCOUNT_URL, MY_ACCOUNT_NAME, MY_ACCOUNT_HOST, accountKey) {
var MY_CORS_XML =
'<?xml version="1.0" encoding="utf-8"?>'+
'<StorageServiceProperties>'+
'<Cors>'+
'<CorsRule>'+
'<AllowedOrigins>*</AllowedOrigins>'+
'<AllowedMethods>GET,PUT</AllowedMethods>'+
'<MaxAgeInSeconds>500</MaxAgeInSeconds>'+
'<ExposedHeaders>x-ms-meta-data*,x-ms-meta-customheader</ExposedHeaders>'+
'<AllowedHeaders>x-ms-meta-target*,x-ms-meta-customheader</AllowedHeaders>'+
'</CorsRule>'+
'</Cors>'+
'<DefaultServiceVersion>2013-08-15</DefaultServiceVersion>'+
'</StorageServiceProperties>';
var url = MY_ACCOUNT_URL + '/?restype=service&comp=properties';
var canonicalizedResource = '/' + MY_ACCOUNT_NAME + '/?comp=properties';
var corsMD5 = crypto.createHash('md5' ).update(MY_CORS_XML).digest('base64');
var date = (new Date()).toUTCString();
var headers = {
'x-ms-version': '2013-08-15',
'x-ms-date': date,
'Host': MY_ACCOUNT_HOST
};
var canonicalizedHeaders = buildCanonicalizedHeaders( headers );
// THIS
var key = buildSharedKeyLite( 'PUT', corsMD5, 'text/plain; charset=UTF-8', canonicalizedHeaders, canonicalizedResource, accountKey);
// AND THIS, BOTH YIELD THE SAME SERVER RESPONSE
// var key = buildSharedKeyLite( 'PUT', "", "", canonicalizedHeaders, canonicalizedResource, accountKey);
headers['Authorization'] = 'SharedKeyLite ' + MY_ACCOUNT_NAME + ':' + key;
var options = {
url: url,
body: MY_CORS_XML,
headers: headers
};
console.log("url : " + url);
console.log("canonicalizedResource : " + canonicalizedResource);
console.log("canonicalizedHeaders : " + canonicalizedHeaders);
console.log("corsMD5 : " + corsMD5);
console.log("key : " + key);
console.log("options : " + JSON.stringify(options));
function onPropertiesSet(error, response, body) {
if (!error && response.statusCode == 202) {
console.log("CORS: OK");
}
else {
console.log("CORS: " + response.statusCode);
console.log("body : " + body);
}
}
request.put(options, onPropertiesSet); // require('request')
};
function buildCanonicalizedHeaders( headers ) {
var xmsHeaders = [];
var canHeaders = "";
for ( var name in headers ) {
if ( name.indexOf('x-ms-') == 0 ) {
xmsHeaders.push( name );
}
}
xmsHeaders.sort();
for ( var i = 0; i < xmsHeaders.length; i++ ) {
name = xmsHeaders[i];
canHeaders = canHeaders + name.toLowerCase().trim() + ':' + headers[name] + '\n';
}
return canHeaders;
}
function buildSharedKeyLite( verb, contentMD5, contentType, canonicalizedHeaders, canonicalizedResource, accountKey) {
var stringToSign = verb + "\n" +
contentMD5 + "\n" +
contentType + "\n" +
"" + "\n" + // date is to be empty because we use x-ms-date
canonicalizedHeaders +
canonicalizedResource;
// return crypto.createHmac('sha256', accountKey).update(encodeURIComponent(stringToSign)).digest('base64');
return crypto.createHmac('sha256', new Buffer(accountKey, 'base64')).update(stringToSign).digest('base64');
}
And here is how I call this function from my server.js file :
var setcrosproperties = require('./setcrosproperties.js');
// setCors(MY_ACCOUNT_URL, MY_ACCOUNT_NAME, MY_ACCOUNT_HOST, accountKey)
setcrosproperties.setCors(
'https://'+process.env['AZURE_STORAGE_ACCOUNT']+'.blob.core.windows.net',
process.env['AZURE_STORAGE_ACCOUNT'],
process.env['AZURE_STORAGE_ACCOUNT']+'.blob.core.windows.net',
process.env['AZURE_STORAGE_ACCESS_KEY']);
I did not understand what was the difference intended with variables MY_ACCOUNT_UTL (I assumed URL) and MY_ACCOUNT_HOST, so I use the same value for both parameters of the function.
(I removed the "cors" parameter, which seemed to be unused.)
Here is what I get in the console :
url : https://NAME_OF_MY_STORAGE_ACCOUNT.blob.core.windows.net/?restype=service&comp=properties
canonicalizedResource : /NAME_OF_MY_STORAGE_ACCOUNT/?comp=properties
canonicalizedHeaders : x-ms-date:Sun, 09 Mar 2014 12:33:41 GMT
x-ms-version:2013-08-15
corsMD5 : +ij...w==
key : sNB...JrY=
options : {"url":"https://NAME_OF_MY_STORAGE_ACCOUNT.blob.core.windows.net/?restype=service&comp=properties","body":"GET,PUT500x-ms-meta-data,x-ms-meta-customheaderx-ms-meta-target*,x-ms-meta-customheader2013-08-15","headers":{"x-ms-version":"2013-08-15","x-ms-date":"Sun, 09 Mar 2014 12:33:41 GMT","Host":"NAME_OF_MY_STORAGE_ACCOUNT.blob.core.windows.net","Authorization":"SharedKeyLite NAME_OF_MY_STORAGE_ACCOUNT:sNB...rY="}}
CORS: 403
body : AuthenticationFailedServer failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.
RequestId:1e6abfe3-e0e8-4b9c-922d-7cb34485eec9
Time:2014-03-09T12:33:41.7262308ZThe MAC signature found in the HTTP request 'sNB...JrY=' is not the same as any computed signature. Server used following string to sign: 'PUT
x-ms-date:Sun, 09 Mar 2014 12:33:41 GMT
x-ms-version:2013-08-15
/NAME_OF_MY_STORAGE_ACCOUNT/?comp=properties'.
Any idea about what I am doing wrong here? Thanks for your help

Answer 1

To configure CORS, use the Azure storage library for Node.js.
You can do npm install azure-storage to get it. Source code is at https://github.com/Azure/azure-storage-node.
The one that come with npm package azure (a.k.a. azure-sdk-for-node) use older azure-storage-legacy package, which does not support CORS.
You can set the CORS with the following code:
var service = azure.createBlobService();
var serviceProperties = {
Cors: {
CorsRule: [{
AllowedOrigins: ['*'],
AllowedMethods: ['GET'],
AllowedHeaders: [],
ExposedHeaders: [],
MaxAgeInSeconds: 60
}]
}
};
service.setServiceProperties(serviceProperties, callback);

Answer 2

Please add Content-Type and Content-MD5 in your headers array and that should do the trick. Here's the modified code:
var crypto = require('crypto');
var request = require('request');
exports.setCors = function (MY_ACCOUNT_URL, MY_ACCOUNT_NAME, MY_ACCOUNT_HOST, accountKey) {
var MY_CORS_XML =
'<?xml version="1.0" encoding="utf-8"?>'+
'<StorageServiceProperties>'+
'<Cors>'+
'<CorsRule>'+
'<AllowedOrigins>*</AllowedOrigins>'+
'<AllowedMethods>GET,PUT</AllowedMethods>'+
'<MaxAgeInSeconds>500</MaxAgeInSeconds>'+
'<ExposedHeaders>x-ms-meta-data*,x-ms-meta-customheader</ExposedHeaders>'+
'<AllowedHeaders>x-ms-meta-target*,x-ms-meta-customheader</AllowedHeaders>'+
'</CorsRule>'+
'</Cors>'+
'<DefaultServiceVersion>2013-08-15</DefaultServiceVersion>'+
'</StorageServiceProperties>';
var url = MY_ACCOUNT_URL + '/?restype=service&comp=properties';
var canonicalizedResource = '/' + MY_ACCOUNT_NAME + '/?comp=properties';
var corsMD5 = crypto.createHash('md5' ).update(MY_CORS_XML).digest('base64');
var date = (new Date()).toUTCString();
var headers = {
'x-ms-version': '2013-08-15',
'x-ms-date': date,
'Host': MY_ACCOUNT_HOST,
'Content-Type': 'text/plain; charset=UTF-8',//Added this line
'Content-MD5': corsMD5,//Added this line
};
var canonicalizedHeaders = buildCanonicalizedHeaders( headers );
// THIS
var key = buildSharedKeyLite( 'PUT', corsMD5, 'text/plain; charset=UTF-8', canonicalizedHeaders, canonicalizedResource, accountKey);
// AND THIS, BOTH YIELD THE SAME SERVER RESPONSE
// var key = buildSharedKeyLite( 'PUT', "", "", canonicalizedHeaders, canonicalizedResource, accountKey);
headers['Authorization'] = 'SharedKeyLite ' + MY_ACCOUNT_NAME + ':' + key;
var options = {
url: url,
body: MY_CORS_XML,
headers: headers
};
console.log("url : " + url);
console.log("canonicalizedResource : " + canonicalizedResource);
console.log("canonicalizedHeaders : " + canonicalizedHeaders);
console.log("corsMD5 : " + corsMD5);
console.log("key : " + key);
console.log("options : " + JSON.stringify(options));
function onPropertiesSet(error, response, body) {
if (!error && response.statusCode == 202) {
console.log("CORS: OK");
}
else {
console.log("CORS: " + response.statusCode);
console.log("body : " + body);
}
}
request.put(options, onPropertiesSet); // require('request')
};
function buildCanonicalizedHeaders( headers ) {
var xmsHeaders = [];
var canHeaders = "";
for ( var name in headers ) {
if ( name.indexOf('x-ms-') == 0 ) {
xmsHeaders.push( name );
}
}
xmsHeaders.sort();
for ( var i = 0; i < xmsHeaders.length; i++ ) {
name = xmsHeaders[i];
canHeaders = canHeaders + name.toLowerCase().trim() + ':' + headers[name] + '\n';
}
return canHeaders;
}
function buildSharedKeyLite( verb, contentMD5, contentType, canonicalizedHeaders, canonicalizedResource, accountKey) {
var stringToSign = verb + "\n" +
contentMD5 + "\n" +
contentType + "\n" +
"" + "\n" + // date is to be empty because we use x-ms-date
canonicalizedHeaders +
canonicalizedResource;
// return crypto.createHmac('sha256', accountKey).update(encodeURIComponent(stringToSign)).digest('base64');
return crypto.createHmac('sha256', new Buffer(accountKey, 'base64')).update(stringToSign).digest('base64');
}