Add CORS headers to HTTP handlers

backend/config/config.go

@@ -41,6 +41,7 @@ type Config struct {
 	S3Bucket             string
 	AssetsHTTPRoot       string
 	FFmpegWorkerPoolSize int
+	CORSAllowedOrigins   []string
 }
 
 const Prefix = "CLIPPER_"
@@ -141,6 +142,12 @@ func NewFromEnv() (Config, error) {
 		}
 	}
 
+	var corsAllowedOrigins []string
+	corsAllowedOriginsName := envPrefix("CORS_ALLOWED_ORIGINS")
+	if s := os.Getenv(corsAllowedOriginsName); s != "" {
+		corsAllowedOrigins = strings.Split(s, ",")
+	}
+
 	return Config{
 		Environment:          env,
 		BindAddr:             bindAddr,
@@ -156,5 +163,6 @@ func NewFromEnv() (Config, error) {
 		FileStoreHTTPRoot:    fileStoreHTTPRoot,
 		FileStoreHTTPBaseURL: fileStoreHTTPBaseURL,
 		FFmpegWorkerPoolSize: ffmpegWorkerPoolSize,
+		CORSAllowedOrigins:   corsAllowedOrigins,
 	}, nil
 }

backend/config/config_test.go

@@ -271,4 +271,24 @@ func TestNewFromEnv(t *testing.T) {
 		assert.Equal(t, "eu-west-1", c.AWSRegion)
 		assert.Equal(t, "bucket", c.S3Bucket)
 	})
+
+	t.Run("CORS_ALLOWED_ORIGINS", func(t *testing.T) {
+		defer clearenv()
+		setupenv()
+
+		os.Setenv("CLIPPER_CORS_ALLOWED_ORIGINS", "")
+		c, err := config.NewFromEnv()
+		require.NoError(t, err)
+		assert.Nil(t, c.CORSAllowedOrigins)
+
+		os.Setenv("CLIPPER_CORS_ALLOWED_ORIGINS", "*")
+		c, err = config.NewFromEnv()
+		require.NoError(t, err)
+		assert.Equal(t, []string{"*"}, c.CORSAllowedOrigins)
+
+		os.Setenv("CLIPPER_CORS_ALLOWED_ORIGINS", "https://www1.example.com,https://www2.example.com")
+		c, err = config.NewFromEnv()
+		require.NoError(t, err)
+		assert.Equal(t, []string{"https://www1.example.com", "https://www2.example.com"}, c.CORSAllowedOrigins)
+	})
 }

backend/go.mod

@@ -40,8 +40,10 @@ require (
 	github.com/desertbit/timer v0.0.0-20180107155436-c41aec40b27f // indirect
 	github.com/dlclark/regexp2 v1.4.1-0.20201116162257-a2a8dda75c91 // indirect
 	github.com/dop251/goja v0.0.0-20220124171016-cfb079cdc7b4 // indirect
+	github.com/felixge/httpsnoop v1.0.1 // indirect
 	github.com/go-sourcemap/sourcemap v2.1.3+incompatible // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/gorilla/handlers v1.5.1 // indirect
 	github.com/jackc/chunkreader/v2 v2.0.1 // indirect
 	github.com/jackc/pgio v1.0.0 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect

backend/go.sum

@@ -151,6 +151,8 @@ github.com/envoyproxy/go-control-plane v0.9.9-0.20210512163311-63b5d3c536b0/go.m
 github.com/envoyproxy/go-control-plane v0.9.10-0.20210907150352-cf90f659a021/go.mod h1:AFq3mo9L8Lqqiid3OhADV3RfLJnjiw63cSpi+fDTRC0=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
 github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=
+github.com/felixge/httpsnoop v1.0.1 h1:lvB5Jl89CsZtGIWuTcDM1E/vkVs49/Ml7JJe07l8SPQ=
+github.com/felixge/httpsnoop v1.0.1/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/franela/goblin v0.0.0-20200105215937-c9ffbefa60db/go.mod h1:7dvUGVsVBjqR7JHJk0brhHOZYGmfBYOrK0ZhYMEtBr4=
 github.com/franela/goreq v0.0.0-20171204163338-bcd34c9993f8/go.mod h1:ZhphrRTfi2rbfLwlschooIH4+wKKDR4Pdxhh+TRoA20=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
@@ -232,6 +234,8 @@ github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
 github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
 github.com/gorilla/context v1.1.1/go.mod h1:kBGZzfjB9CEq2AlWe17Uuf7NDRt0dE0s8S51q0aT7Yg=
+github.com/gorilla/handlers v1.5.1 h1:9lRY6j8DEeeBT10CvO9hGW0gmky0BprnvDI5vfhUHH4=
+github.com/gorilla/handlers v1.5.1/go.mod h1:t8XrUpc4KVXb7HGyJ4/cEnwQiaxrX/hz1Zv/4g96P1Q=
 github.com/gorilla/mux v1.6.2/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=
 github.com/gorilla/mux v1.7.3/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=
 github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=

backend/server/handler.go

@@ -10,6 +10,7 @@ import (
 	"git.netflux.io/rob/clipper/filestore"
 	"git.netflux.io/rob/clipper/media"
 	"github.com/google/uuid"
+	"github.com/gorilla/handlers"
 	"github.com/gorilla/mux"
 	"github.com/gorilla/schema"
 	"github.com/improbable-eng/grpc-web/go/grpcweb"
@@ -50,7 +51,7 @@ func newHTTPHandler(grpcHandler *grpcweb.WrappedGrpcServer, mediaSetService Medi
 	h.
 		Methods("POST").
 		Path("/api/media_sets/{id}/clip").
-		HandlerFunc(h.handleClip)
+		Handler(http.HandlerFunc(h.handleClip))
 
 	if c.FileStore == config.FileSystemStore {
 		h.
@@ -63,6 +64,8 @@ func newHTTPHandler(grpcHandler *grpcweb.WrappedGrpcServer, mediaSetService Medi
 		Methods("GET").
 		Handler(assetsHandler)
 
+	h.Use(handlers.CORS(handlers.AllowedOrigins(c.CORSAllowedOrigins)))
+
 	return h
 }
 

backend/server/handler_test.go

@@ -20,13 +20,14 @@ import (
 
 func TestHandler(t *testing.T) {
 	testCases := []struct {
-		name                                       string
-		path, body, method, contentType            string
-		config                                     config.Config
-		wantStartFrame, wantEndFrame               int64
-		wantAudioFormat                            media.AudioFormat
-		wantStatus                                 int
-		wantContentType, wantContentDisp, wantBody string
+		name                                    string
+		path, body, method, contentType, origin string
+		config                                  config.Config
+		wantStartFrame, wantEndFrame            int64
+		wantAudioFormat                         media.AudioFormat
+		wantStatus                              int
+		wantHeaders                             map[string]string
+		wantBody                                string
 	}{
 		{
 			name:       "assets disabled, file system store disabled, GET /",
@@ -111,6 +112,32 @@ func TestHandler(t *testing.T) {
 			config:     config.Config{FileStore: config.FileSystemStore, FileStoreHTTPBaseURL: mustParseURL(t, "/"), FileStoreHTTPRoot: "testdata/http/filestore", AssetsHTTPRoot: "testdata/http/assets"},
 			wantStatus: http.StatusNotFound,
 		},
+		{
+			name:   "assets enabled, configured with custom Allowed-Origins header, origin does not match",
+			path:   "/css/style.css",
+			method: http.MethodGet,
+			origin: "https://localhost:3000",
+			config: config.Config{
+				FileStore:          config.S3Store,
+				AssetsHTTPRoot:     "testdata/http/assets",
+				CORSAllowedOrigins: []string{"https://www.example.com"},
+			},
+			wantHeaders: map[string]string{"access-control-allow-origin": ""},
+			wantStatus:  http.StatusOK,
+		},
+		{
+			name:   "assets enabled, configured with custom Allowed-Origins header, origin does match",
+			path:   "/css/style.css",
+			method: http.MethodGet,
+			origin: "https://www.example.com",
+			config: config.Config{
+				FileStore:          config.S3Store,
+				AssetsHTTPRoot:     "testdata/http/assets",
+				CORSAllowedOrigins: []string{"https://www.example.com"},
+			},
+			wantHeaders: map[string]string{"access-control-allow-origin": "https://www.example.com"},
+			wantStatus:  http.StatusOK,
+		},
 		{
 			name:        "POST /api/media_sets/:id/clip, NOK, no body",
 			path:        "/api/media_sets/05951a4d-584e-4056-9ae7-08b9e4cd355d/clip",
@@ -147,10 +174,12 @@ func TestHandler(t *testing.T) {
 			wantStartFrame:  0,
 			wantEndFrame:    1024,
 			wantAudioFormat: media.AudioFormatMP3,
-			wantContentType: "audio/mp3",
-			wantContentDisp: "attachment; filename=clip.mp3",
-			wantStatus:      http.StatusOK,
-			wantBody:        "an audio file",
+			wantHeaders: map[string]string{
+				"content-type":        "audio/mp3",
+				"content-disposition": "attachment; filename=clip.mp3",
+			},
+			wantStatus: http.StatusOK,
+			wantBody:   "an audio file",
 		},
 		{
 			name:            "POST /api/media_sets/:id/clip, WAV, OK",
@@ -162,10 +191,12 @@ func TestHandler(t *testing.T) {
 			wantStartFrame:  4096,
 			wantEndFrame:    8192,
 			wantAudioFormat: media.AudioFormatWAV,
-			wantContentType: "audio/wav",
-			wantContentDisp: "attachment; filename=clip.wav",
-			wantStatus:      http.StatusOK,
-			wantBody:        "an audio file",
+			wantHeaders: map[string]string{
+				"content-type":        "audio/wav",
+				"content-disposition": "attachment; filename=clip.wav",
+			},
+			wantStatus: http.StatusOK,
+			wantBody:   "an audio file",
 		},
 	}
 
@@ -192,6 +223,9 @@ func TestHandler(t *testing.T) {
 				body = strings.NewReader(tc.body)
 			}
 			req := httptest.NewRequest(tc.method, tc.path, body)
+			if tc.origin != "" {
+				req.Header.Add("origin", tc.origin)
+			}
 			if tc.contentType != "" {
 				req.Header.Add("content-type", tc.contentType)
 			}
@@ -206,11 +240,8 @@ func TestHandler(t *testing.T) {
 				require.NoError(t, err)
 				assert.Equal(t, tc.wantBody, string(body))
 			}
-			if tc.wantContentType != "" {
-				assert.Equal(t, tc.wantContentType, resp.Header.Get("content-type"))
-			}
-			if tc.wantContentDisp != "" {
-				assert.Equal(t, tc.wantContentDisp, resp.Header.Get("content-disposition"))
+			for k, v := range tc.wantHeaders {
+				assert.Equal(t, v, resp.Header.Get(k))
 			}
 		})
 	}

backend/server/server.go

@@ -99,6 +99,7 @@ func Start(options Options) error {
 	mediaSetController := &mediaSetServiceController{mediaSetService: mediaSetService, logger: options.Logger.Sugar().Named("controller")}
 	pbmediaset.RegisterMediaSetServiceServer(grpcServer, mediaSetController)
 
+	// TODO: implement CORS headers
 	grpcHandler := grpcweb.WrapServer(grpcServer, grpcweb.WithOriginFunc(func(string) bool { return true }))
 	httpHandler := newHTTPHandler(grpcHandler, mediaSetService, conf, options.Logger.Sugar().Named("httpHandler"))