set cors

api/api.go

@@ -60,6 +60,13 @@ func SetJsonContinuation(context *types.RequestContext, req *http.Request, resp
 	}
 }
 
+func SetCorsContinuation(context *types.RequestContext, req *http.Request, resp http.ResponseWriter) types.ContinuationChain {
+	return func(success types.Continuation, _failure types.Continuation) types.ContinuationChain {
+		resp.Header().Set("Access-Control-Allow-Origin", "*")
+		return success(context, req, resp)
+	}
+}
+
 func CacheControlMiddleware(next http.Handler, maxAge int) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		header := fmt.Sprintf("public, max-age=%d", maxAge)
@@ -68,6 +75,15 @@ func CacheControlMiddleware(next http.Handler, maxAge int) http.Handler {
 	})
 }
 
+// basically b(a(message)) if and only if b is successful
+func Compose(a types.Continuation, b types.Continuation) types.Continuation {
+	return func(context *types.RequestContext, req *http.Request, resp http.ResponseWriter) types.ContinuationChain {
+		return func(success types.Continuation, failure types.Continuation) types.ContinuationChain {
+			return b(context, req, resp)(a, FailurePassingContinuation)(success, failure)
+		}
+	}
+}
+
 func MakeMux(argv *args.Arguments, dbConn *sql.DB) *http.ServeMux {
 	mux := http.NewServeMux()
 
@@ -95,8 +111,8 @@ func MakeMux(argv *args.Arguments, dbConn *sql.DB) *http.ServeMux {
 
 	mux.HandleFunc("GET /updates", func(w http.ResponseWriter, r *http.Request) {
 		requestContext := makeRequestContext()
-
+    continuation := Compose(template.TemplateContinuation("updates.json.tmpl", false), Compose(whois.ListUpdates, Compose(SetJsonContinuation, SetCorsContinuation)))
-		LogRequestContinuation(requestContext, r, w)(whois.ListUpdates, FailurePassingContinuation)(SetJsonContinuation, FailurePassingContinuation)(template.TemplateContinuation("updates.json.tmpl", false), FailurePassingContinuation)(LogExecutionTimeContinuation, LogExecutionTimeContinuation)(IdContinuation, IdContinuation)
+		LogRequestContinuation(requestContext, r, w)(continuation, FailurePassingContinuation)(LogExecutionTimeContinuation, LogExecutionTimeContinuation)(IdContinuation, IdContinuation)
 	})
 
 	return mux