small refactoring of the HTTP handlers to share common code

fe/http.go

@@ -89,27 +89,29 @@ func (h *HttpRedirector) pickActiveNode() string {
 	return result.IP
 }
 
-// Parse the request and extract the mount path.
-func (h *HttpRedirector) getMount(r *http.Request) (*autoradio.Mount, error) {
-	path := r.URL.Path
-	if strings.HasSuffix(path, ".m3u") {
-		path = path[:len(path)-4]
-	}
-	return h.client.GetMount(path)
+func makeIcecastAddr(server string) string {
+	return net.JoinHostPort(server, strconv.Itoa(autoradio.IcecastPort))
 }
 
-func makeIcecastUrl(server string) string {
-	return net.JoinHostPort(server, strconv.Itoa(autoradio.IcecastPort))
+func makeIcecastUrl(server, mountName string) string {
+	return fmt.Sprintf("http://%s%s", makeIcecastAddr(server), mountName)
 }
 
-// Serve a response for a client connection to a relay.
-func (h *HttpRedirector) serveRelay(w http.ResponseWriter, r *http.Request) {
-	mount, err := h.getMount(r)
-	if err != nil {
-		http.Error(w, "Not Found", http.StatusNotFound)
-		return
-	}
+// Request wrapper that passes a Mount along with the HTTP request.
+func (h *HttpRedirector) withMount(f func(*autoradio.Mount, http.ResponseWriter, *http.Request)) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		mountPath := strings.TrimSuffix(r.URL.Path, ".m3u")
+		mount, err := h.client.GetMount(mountPath)
+		if err != nil {
+			http.Error(w, "Not Found", http.StatusNotFound)
+			return
+		}
+		f(mount, w, r)
+	})
+}
 
+// Serve a response for a client connection to a relay.
+func (h *HttpRedirector) serveRelay(mount *autoradio.Mount, w http.ResponseWriter, r *http.Request) {
 	// Find an active node.
 	relayAddr := h.pickActiveNode()
 	if relayAddr == "" {
@@ -119,23 +121,18 @@ func (h *HttpRedirector) serveRelay(w http.ResponseWriter, r *http.Request) {
 	httpTargetStats.IncrVar(ipToMetric(relayAddr))
 
 	// Create the m3u response.
-	m3u := fmt.Sprintf("http://%s%s\n", makeIcecastUrl(relayAddr), mount.Name)
+	m3u := fmt.Sprintf("%s\n", makeIcecastUrl(relayAddr, mount.Name))
 	w.Header().Set("Content-Length", strconv.Itoa(len(m3u)))
 	w.Header().Set("Content-Type", "audio/x-mpegurl")
-	w.Header().Set("Expires", "-1")
-	w.Header().Set("Cache-Control", "private, max-age=0")
+	addDefaultHeaders(w)
 	io.WriteString(w, m3u)
 }
 
-func (h *HttpRedirector) serveSource(w http.ResponseWriter, r *http.Request) {
-	m, err := h.getMount(r)
-	if err != nil || m.IsRelay() {
-		if err != nil {
-			log.Printf("source: error retrieving mount for %+v: %s", r, err)
-		} else {
-			log.Printf("source: connection to relay stream %s", m.Name)
-		}
-		http.Error(w, "Not Found", http.StatusNotFound)
+// Handle SOURCE requests.
+func (h *HttpRedirector) serveSource(mount *autoradio.Mount, w http.ResponseWriter, r *http.Request) {
+	if mount.IsRelay() {
+		log.Printf("source: connection to relay stream %s", mount.Name)
+		http.Error(w, "Source Connection To Relay Stream", http.StatusBadRequest)
 		source404Errors.Incr()
 		return
 	}
@@ -161,7 +158,7 @@ func (h *HttpRedirector) serveSource(w http.ResponseWriter, r *http.Request) {
 	// Create the upstream connection, and write the original
 	// request to it as-is (the URL path on the backend is the
 	// same, and the headers do not need to change).
-	upstream, err := net.Dial("tcp", makeIcecastUrl(masterAddr))
+	upstream, err := net.Dial("tcp", makeIcecastAddr(masterAddr))
 	if err != nil {
 		log.Printf("source: dial upstream: %v", err)
 		sendErr(err)
@@ -217,6 +214,7 @@ func (h *HttpRedirector) serveSource(w http.ResponseWriter, r *http.Request) {
 	wg.Wait()
 }
 
+// Serve our cluster status page.
 func (h *HttpRedirector) serveStatusPage(w http.ResponseWriter, r *http.Request) {
 	nodes, _ := h.client.GetNodes()
 	mounts, _ := h.client.ListMounts()
@@ -233,8 +231,7 @@ func (h *HttpRedirector) serveStatusPage(w http.ResponseWriter, r *http.Request)
 	}
 	w.Header().Set("Content-Type", "text/html; charset=utf-8")
 	w.Header().Set("Content-Length", strconv.Itoa(buf.Len()))
-	w.Header().Set("Expires", "-1")
-	w.Header().Set("Cache-Control", "private, max-age=0")
+	addDefaultHeaders(w)
 	w.Write(buf.Bytes())
 }
 
@@ -247,6 +244,7 @@ func (h *HttpRedirector) Run(addr, staticDir, templateDir string) {
 	// Create our HTTP handler stack. Passes the /debug/ queries
 	// along to the global ServeMux (where moodules such as pprof
 	// install their handlers).
+	relayHandler := h.withMount(h.serveRelay)
 	mux := http.NewServeMux()
 	mux.Handle(
 		"/static/",
@@ -260,7 +258,7 @@ func (h *HttpRedirector) Run(addr, staticDir, templateDir string) {
 		case strings.HasPrefix(r.URL.Path, "/debug/"):
 			http.DefaultServeMux.ServeHTTP(w, r)
 		default:
-			h.serveRelay(w, r)
+			relayHandler.ServeHTTP(w, r)
 		}
 	})
 
@@ -275,9 +273,10 @@ func (h *HttpRedirector) Run(addr, staticDir, templateDir string) {
 	// handlers: since they wrap the ResponseWriter, we would be
 	// unable to hijack the underlying connection for proxying.
 	// TODO: look into using WrapWriter.
+	sourceHandler := h.withMount(h.serveSource)
 	rooth := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.Method == "SOURCE" {
-			h.serveSource(w, r)
+			sourceHandler.ServeHTTP(w, r)
 		} else {
 			wraph.ServeHTTP(w, r)
 		}
@@ -293,3 +292,8 @@ func (h *HttpRedirector) Run(addr, staticDir, templateDir string) {
 	log.Printf("starting HTTP server on %s/tcp", httpServer.Addr)
 	log.Fatal(httpServer.ListenAndServe())
 }
+
+func addDefaultHeaders(w http.ResponseWriter) {
+	w.Header().Set("Expires", "-1")
+	w.Header().Set("Cache-Control", "private, max-age=0")
+}