add cors headers to ui/webserver fn responses

ui/webserver.go

@@ -37,6 +37,13 @@ func NewWebServer(h *holo.Holochain, port string) *WebServer {
 	return &w
 }
 
+// Helper for managing CORS responses
+func AddCors(w http.ResponseWriter) {
+	headers := w.Header()
+	headers.Set("Access-Control-Allow-Origin", "*")
+	headers.Set("Access-Control-Allow-Headers", "Content-Type")
+}
+
 //Start starts up a web server and returns a channel which will shutdown
 func (ws *WebServer) Start() {
 
@@ -104,6 +111,11 @@ func (ws *WebServer) Start() {
 
 		ws.log.Logf("REQUEST:%v", r)
 
+		AddCors(w)
+		if r.Method == "OPTIONS" {
+			return
+		}
+
 		body, err := ioutil.ReadAll(r.Body)
 		if err != nil {
 			errCode, err = mkErr("unable to read body", 500)
@@ -190,6 +202,11 @@ func (ws *WebServer) Start() {
 			}
 		}()
 
+		AddCors(w)
+		if r.Method == "OPTIONS" {
+			return
+		}
+
 		body, err := ioutil.ReadAll(r.Body)
 		if err != nil {
 			errCode, err = mkErr("unable to read body", 500)

ui/webserver_test.go

@@ -59,6 +59,15 @@ func TestWebServer(t *testing.T) {
 		So(string(b), ShouldEqual, "en")
 	})
 
+	Convey("it should return CORS headers when calling functions", t, func() {
+		body := bytes.NewBuffer([]byte("language"))
+		resp, err := http.Post("http://0.0.0.0:31415/fn/jsSampleZome/getProperty", "", body)
+		So(err, ShouldBeNil)
+		defer resp.Body.Close()
+		_, corsPresent := resp.Header["Access-Control-Allow-Origin"]
+		So(corsPresent, ShouldEqual, true)
+	})
+
 	Convey("it should return Holochain errors from call functions as 400", t, func() {
 		body := bytes.NewBuffer([]byte("2"))
 		resp, err := http.Post("http://0.0.0.0:31415/fn/jsSampleZome/addOdd", "", body)