storage: support signed urls.

lib/storage/index.js

@@ -20,6 +20,7 @@
 
 'use strict';
 
+var crypto = require('crypto');
 var duplexify = require('duplexify');
 var nodeutil = require('util');
 var stream = require('stream');
@@ -230,6 +231,64 @@ Bucket.prototype.remove = function(name, callback) {
   this.makeReq('DELETE', path, null, true, callback);
 };
 
+/**
+ * Get a signed URL to allow limited time access to a resource.
+ *
+ * {@link https://developers.google.com/storage/docs/accesscontrol#Signed-URLs}
+ *
+ * @param {object} options - Configuration object.
+ * @param {string} options.action - "read", "write", or "delete"
+ * @param {string=} options.contentMd5 - The MD5 digest value in base64. If you
+ *     provide this, the client must provide this HTTP header with this same
+ *     value in its request.
+ * @param {string=} options.contentType - If you provide this value, the client
+ *     must provide this HTTP header set to the same value.
+ * @param {number} options.expires - Timestamp (seconds since epoch) when this
+ *     link will expire.
+ * @param {string=} options.extensionHeaders - If these headers are used, the
+ *     server will check to make sure that the client provides matching values.
+ * @param {string} options.resource - Resource to allow access to.
+ * @return {string}
+ *
+ * @example
+ * ```js
+ * var signedUrl = bucket.getSignedUrl({
+ *   action: 'read',
+ *   expires: Math.round(Date.now() / 1000) + (60 * 60 * 24 * 14), // 2 weeks.
+ *   resource: 'my-dog.jpg'
+ * });
+ * ```
+ */
+Bucket.prototype.getSignedUrl = function(options) {
+  options.action = {
+      read: 'GET',
+      write: 'PUT',
+      delete: 'DELETE'
+    }[options.action];
+
+  options.resource = util.format('/{bucket}/{resource}', {
+      bucket: this.bucketName,
+      resource: options.resource
+    });
+
+  var sign = crypto.createSign('RSA-SHA256');
+  sign.update([
+      options.action,
+      (options.contentMd5 || ''),
+      (options.contentType || ''),
+      options.expires,
+      (options.extensionHeaders || '') + options.resource
+    ].join('\n'));
+  var signature = sign.sign(this.conn.credentials.private_key, 'base64');
+
+  return [
+      'http://storage.googleapis.com' + options.resource,
+      '?GoogleAccessId=' + this.conn.credentials.client_email,
+      '&Expires=' + options.expires,
+      '&Signature=' + encodeURIComponent(signature)
+    ].join('');
+};
+
 /**
  * Create a readable stream to read contents of the provided remote file. It
  * can be piped to a write stream, or listened to for 'data' events to read a

regression/storage.js

@@ -14,14 +14,15 @@
  * limitations under the License.
  */
 
-/*global describe, it, before, after */
+/*global describe, it, before, after, beforeEach */
 
 'use strict';
 
 var assert = require('assert');
 var async = require('async');
 var crypto = require('crypto');
 var fs = require('fs');
+var request = require('request');
 var tmp = require('tmp');
 
 var env = require('./env.js');
@@ -189,4 +190,62 @@ describe('storage', function() {
         }), done);
     });
   });
+
+  describe('sign urls', function() {
+    var fileName = 'LogoToSign.jpg';
+
+    beforeEach(function(done) {
+      fs.createReadStream(files.logo.path)
+          .pipe(bucket.createWriteStream(fileName))
+          .on('error', done)
+          .on('complete', done.bind(null, null));
+    });
+
+    it('should create a signed read url', function(done) {
+      var signedReadUrl = bucket.getSignedUrl({
+          action: 'read',
+          expires: Math.round(Date.now() / 1000) + 5,
+          resource: fileName
+        });
+      var localFile = fs.readFileSync(files.logo.path);
+      request.get(signedReadUrl, function(err, resp, body) {
+        assert.equal(body, localFile);
+        bucket.remove(fileName, done);
+      });
+    });
+
+    it('should create a signed delete url', function(done) {
+      var signedDeleteUrl = bucket.getSignedUrl({
+          action: 'delete',
+          expires: Math.round(Date.now() / 1000) + 5,
+          resource: fileName
+        });
+      request.del(signedDeleteUrl, function(err, resp) {
+        assert.equal(resp.statusCode, 204);
+        bucket.stat(fileName, function(err) {
+          assert.equal(err.code, 404);
+          done();
+        });
+      });
+    });
+
+    it('should allow control of expiration', function(done) {
+      var offsetSeconds = 5;
+      var signedReadUrl = bucket.getSignedUrl({
+          action: 'read',
+          expires: Math.round(Date.now() / 1000) + offsetSeconds,
+          resource: fileName
+        });
+      var localFile = fs.readFileSync(files.logo.path);
+      request.get(signedReadUrl, function(err, resp, body) {
+        assert.equal(body, localFile);
+      });
+      setTimeout(function() {
+        request.get(signedReadUrl, function(err, resp) {
+          assert.equal(resp.statusCode, 400);
+          bucket.remove(fileName, done);
+        });
+      }, (offsetSeconds + 1) * 1000);
+    });
+  });
 });