gistfile1.diff

diff --git a/www/index.html b/www/index.html
index 1aafce9..648bcd8 100644
--- a/www/index.html
+++ b/www/index.html
@@ -32,6 +32,11 @@
     /* exported Run */
     /* globals libndt7 */
 
+    function MaybeHostname() {
+      const url = new URL(window.location.href)
+      return (url.hash !== '') ? url.hash.substring(1) : ''
+    }
+
     function WithElementIdDo(elementId, callable) {
       const elem = document.getElementById(elementId)
       if (elem) {
@@ -51,7 +56,7 @@
       worker.postMessage({
         key: 'download',
         value: {
-          href: window.location.href
+          hostname: MaybeHostname()
         },
       })
       worker.onmessage = function (ev) {
@@ -72,7 +77,7 @@
       worker.postMessage({
         key: 'upload',
         value: {
-          href: window.location.href
+          hostname: MaybeHostname()
         },
       })
       worker.onmessage = function (ev) {
diff --git a/www/libndt7-core.js b/www/libndt7-core.js
index 73cc905..acdd14c 100644
--- a/www/libndt7-core.js
+++ b/www/libndt7-core.js
@@ -55,8 +55,7 @@ const libndt7 = (function () {
 
       // makeurl creates the URL from |settings| and |subtest| name.
       const makeurl = function (settings, subtest) {
-        let url = new URL(settings.href)
-        url.protocol = (url.protocol === 'https:') ? 'wss:' : 'ws:'
+        let url = new URL('wss://' + settings.hostname)
         url.pathname = '/ndt/v7/' + subtest
         let params = new URLSearchParams()
         settings.meta = (settings.meta !== undefined) ? settings : {}
@@ -165,6 +164,39 @@ const libndt7 = (function () {
         }
       }
 
+      // discoverHostname ensures settings.hostname is not empty, using
+      // mlab-ns to find out a suitable hostname if needed.
+      const discoverHostname = function (settings, callback) {
+        if (settings.hostname !== '') {
+          // Allow the user to specify a simplified hostname.
+          const re = /^mlab[1-9]{1}-[a-z]{3}[0-9]{2}$/
+          if (settings.hostname.match(re)) {
+            settings.hostname = `ndt-iupui-${settings.hostname}.measurement-lab.org`
+          }
+          callback(settings)
+          return
+        }
+        // Implementation note: using the geo_options policy because in some
+        // sites, e.g. Turin, there is no mlab4. Using a testing mlabns service
+        // that returns us also the mlab4 sites if available. Of course, this
+        // will need to change when m-lab/ndt-server is widely deployed.
+        fetch('https://locate-dot-mlab-staging.appspot.com/ndt_ssl?policy=geo_options')
+          .then(function (response) {
+            return response.json()
+          })
+          .then(function (doc) {
+            for (let i = 0; i < doc.length; ++i) {
+              const fqdn = doc[i].fqdn
+              if (fqdn.indexOf("-mlab4-") !== -1) {
+                settings.hostname = fqdn
+                callback(settings)
+                return
+              }
+            }
+            throw "Cannot find a suitable mlab server"
+          })
+      }
+
       return {
         // on is a publicly exported function that allows to set a handler
         // for a specific event emitted by this library. |key| is the handler
@@ -175,12 +207,16 @@ const libndt7 = (function () {
 
         // startDownload starts the ndt7 download.
         startDownload: function () {
-          download(setupconn(settings, 'download'))
+          discoverHostname(settings, function (settings) {
+            download(setupconn(settings, 'download'))
+          })
         },
 
         // startUpload starts the ndt7 upload.
         startUpload: function () {
-          upload(setupconn(settings, 'upload'))
+          discoverHostname(settings, function (settings) {
+            upload(setupconn(settings, 'upload'))
+          })
         }
       }
     }