Make url-add follow HTTP redirections

fix #513

Author: maxlath

src/util/url-add.js

@@ -25,28 +25,41 @@ module.exports = (arg) => {
       opts = {}
     }
 
-    if (typeof url !== 'string' ||
-        !url.startsWith('http')) {
+    if (!validUrl(url)) {
       return callback(new Error('"url" param must be an http(s) url'))
     }
 
     callback = once(callback)
 
-    request(parseUrl(url).protocol)(url, (res) => {
-      res.once('error', callback)
-      if (res.statusCode >= 400) {
-        return callback(new Error(`Failed to download with ${res.statusCode}`))
-      }
+    requestWithRedirect(url, opts, send, callback)
+  })
+}
+
+const validUrl = (url) => typeof url === 'string' && url.startsWith('http')
+
+const requestWithRedirect = (url, opts, send, callback) => {
+  request(parseUrl(url).protocol)(url, (res) => {
+    res.once('error', callback)
+    if (res.statusCode >= 400) {
+      return callback(new Error(`Failed to download with ${res.statusCode}`))
+    }
 
+    const redirection = res.headers.location
+
+    if (redirection) {
+      if (!validUrl(redirection)) {
+        return callback(new Error('redirection url must be an http(s) url'))
+      }
+      requestWithRedirect(redirection, opts, send, callback)
+    } else {
       const params = {
         path: 'add',
         qs: opts,
         files: res
       }
-
       // Transform the response stream to DAGNode values
       const transform = (res, callback) => DAGNodeStream.streamToValue(send, res, callback)
       send.andTransform(params, transform, callback)
-    }).end()
-  })
+    }
+  }).end()
 }