Add CORS middleware handler to the API.

http/handler.go

@@ -8,6 +8,8 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/rs/cors"
+
 	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
 
 	cmds "github.com/ipfs/go-ipfs/commands"
@@ -16,10 +18,17 @@ import (
 
 var log = u.Logger("commands/http")
 
+// the internal handler for the API
+type internalHandler struct {
+	ctx  cmds.Context
+	root *cmds.Command
+}
+
+// The Handler struct is funny because we want to wrap our internal handler
+// with CORS while keeping our fields.
 type Handler struct {
-	ctx    cmds.Context
-	root   *cmds.Command
-	origin string
+	internalHandler
+	corsHandler http.Handler
 }
 
 var ErrNotFound = errors.New("404 page not found")
@@ -39,16 +48,31 @@ var mimeTypes = map[string]string{
 	cmds.Text: "text/plain",
 }
 
-func NewHandler(ctx cmds.Context, root *cmds.Command, origin string) *Handler {
+func NewHandler(ctx cmds.Context, root *cmds.Command, allowedOrigin string) *Handler {
 	// allow whitelisted origins (so we can make API requests from the browser)
-	if len(origin) > 0 {
-		log.Info("Allowing API requests from origin: " + origin)
+	if len(allowedOrigin) > 0 {
+		log.Info("Allowing API requests from origin: " + allowedOrigin)
 	}
 
-	return &Handler{ctx, root, origin}
+	// Create a handler for the API.
+	internal := internalHandler{ctx, root}
+
+	// Create a CORS object for wrapping the internal handler.
+	c := cors.New(cors.Options{
+		AllowedMethods: []string{"GET", "POST", "PUT"},
+
+		// use AllowOriginFunc instead of AllowedOrigins because we want to be
+		// restrictive by default.
+		AllowOriginFunc: func(origin string) bool {
+			return (allowedOrigin == "*") || (origin == allowedOrigin)
+		},
+	})
+
+	// Wrap the internal handler with CORS handling-middleware.
+	return &Handler{internal, c.Handler(internal)}
 }
 
-func (i Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+func (i internalHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	log.Debug("Incoming API request: ", r.URL)
 
 	// error on external referers (to prevent CSRF attacks)
@@ -65,11 +89,6 @@ func (i Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if len(i.origin) > 0 {
-		w.Header().Set("Access-Control-Allow-Origin", i.origin)
-	}
-	w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
-
 	req, err := Parse(r, i.root)
 	if err != nil {
 		if err == ErrNotFound {
@@ -168,6 +187,11 @@ func (i Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	flushCopy(w, out)
 }
 
+func (i Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// Call the CORS handler which wraps the internal handler.
+	i.corsHandler.ServeHTTP(w, r)
+}
+
 // flushCopy Copies from an io.Reader to a http.ResponseWriter.
 // Flushes chunks over HTTP stream as they are read (if supported by transport).
 func flushCopy(w http.ResponseWriter, out io.Reader) error {

http/handler_test.go

+package http
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/ipfs/go-ipfs/commands"
+)
+
+func assertHeaders(t *testing.T, resHeaders http.Header, reqHeaders map[string]string) {
+	for name, value := range reqHeaders {
+		if resHeaders.Get(name) != value {
+			t.Errorf("Invalid header `%s', wanted `%s', got `%s'", name, value, resHeaders.Get(name))
+		}
+	}
+}
+
+func TestDisallowedOrigin(t *testing.T) {
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequest("GET", "http://example.com/foo", nil)
+	req.Header.Add("Origin", "http://barbaz.com")
+
+	handler := NewHandler(commands.Context{}, nil, "")
+	handler.ServeHTTP(res, req)
+
+	assertHeaders(t, res.Header(), map[string]string{
+		"Access-Control-Allow-Origin":      "",
+		"Access-Control-Allow-Methods":     "",
+		"Access-Control-Allow-Credentials": "",
+		"Access-Control-Max-Age":           "",
+		"Access-Control-Expose-Headers":    "",
+	})
+}
+
+func TestWildcardOrigin(t *testing.T) {
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequest("GET", "http://example.com/foo", nil)
+	req.Header.Add("Origin", "http://foobar.com")
+
+	handler := NewHandler(commands.Context{}, nil, "*")
+	handler.ServeHTTP(res, req)
+
+	assertHeaders(t, res.Header(), map[string]string{
+		"Access-Control-Allow-Origin":      "http://foobar.com",
+		"Access-Control-Allow-Methods":     "",
+		"Access-Control-Allow-Headers":     "",
+		"Access-Control-Allow-Credentials": "",
+		"Access-Control-Max-Age":           "",
+		"Access-Control-Expose-Headers":    "",
+	})
+}
+
+func TestAllowedMethod(t *testing.T) {
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequest("OPTIONS", "http://example.com/foo", nil)
+	req.Header.Add("Origin", "http://www.foobar.com")
+	req.Header.Add("Access-Control-Request-Method", "PUT")
+
+	handler := NewHandler(commands.Context{}, nil, "http://www.foobar.com")
+	handler.ServeHTTP(res, req)
+
+	assertHeaders(t, res.Header(), map[string]string{
+		"Access-Control-Allow-Origin":      "http://www.foobar.com",
+		"Access-Control-Allow-Methods":     "PUT",
+		"Access-Control-Allow-Headers":     "",
+		"Access-Control-Allow-Credentials": "",
+		"Access-Control-Max-Age":           "",
+		"Access-Control-Expose-Headers":    "",
+	})
+}