Fixes ETag header generation and status code handling. (#35)

fix: Fixes ETag header generation and status code handling.

README.md

@@ -54,6 +54,7 @@ Flags:
       --banner string          markdown text to be rendered at the top of the directory listing page
       --cors                   enable CORS support by setting the "Access-Control-Allow-Origin" header to "*"
       --disable-cache-buster   disable the cache buster for assets from the directory listing feature
+      --disable-etag           disable ETag header generation
       --disable-markdown       disable the markdown rendering feature
       --ensure-unexpired-jwt   enable time validation for JWT claims "exp" and "nbf"
   -h, --help                   help for http-server

app.go

@@ -101,6 +101,7 @@ func run() error {
 	flags.StringVar(&server.JWTSigningKey, "jwt-key", "", "signing key for JWT authentication")
 	flags.BoolVar(&server.ValidateTimedJWT, "ensure-unexpired-jwt", false, "enable time validation for JWT claims \"exp\" and \"nbf\"")
 	flags.StringVar(&server.BannerMarkdown, "banner", "", "markdown text to be rendered at the top of the directory listing page")
+	flags.BoolVar(&server.ETagDisabled, "disable-etag", false, "disable ETag header generation")
 
 	return rootCmd.Execute()
 }

internal/mw/etag.go

@@ -44,31 +44,45 @@ func (e *etagResponseWriter) hasHashed() bool {
 }
 
 // Etag is a middleware that will calculate the ETag header for the response.
-func Etag(next http.Handler) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		ew := etagResponseWriter{
-			rw:   w,
-			buf:  bytes.NewBuffer(nil),
-			hash: sha1.New(),
-		}
+func Etag(enabled bool) func(next http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if !enabled {
+				next.ServeHTTP(w, r)
+				return
+			}
 
-		next.ServeHTTP(&ew, r)
+			ew := etagResponseWriter{
+				rw:   w,
+				buf:  bytes.NewBuffer(nil),
+				hash: sha1.New(),
+			}
 
-		if !ew.hasHashed() {
-			w.Write(ew.buf.Bytes())
-			return
-		}
+			next.ServeHTTP(&ew, r)
+
+			if !ew.hasHashed() {
+				w.WriteHeader(ew.status)
+				w.Write(ew.buf.Bytes())
+				return
+			}
 
-		sum := hex.EncodeToString(ew.hash.Sum(nil))
-		w.Header().Set("ETag", "\""+sum+"\"")
+			sum := hex.EncodeToString(ew.hash.Sum(nil))
+			w.Header().Set("ETag", "\""+sum+"\"")
 
-		if r.Header.Get("If-None-Match") == w.Header().Get("Etag") {
-			w.WriteHeader(http.StatusNotModified)
-			w.Write(nil)
-			return
-		}
+			if r.Header.Get("If-None-Match") == w.Header().Get("Etag") {
+				w.WriteHeader(http.StatusNotModified)
+				w.Write(nil)
+				return
+			}
 
-		w.WriteHeader(ew.status)
-		w.Write(ew.buf.Bytes())
-	})
+			w.WriteHeader(ew.status)
+			w.Write(ew.buf.Bytes())
+		})
+	}
 }
+
+// func Etag(next http.Handler) http.Handler {
+// 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+// 		next.ServeHTTP(w, r)
+// 	})
+// }

internal/server/handlers.go

@@ -160,7 +160,7 @@ func (s *Server) walk(requestedPath string, w http.ResponseWriter, r *http.Reque
 // serveFile serves a file with the appropriate headers, including support
 // for ETag and Last-Modified headers, as well as range requests.
 func (s *Server) serveFile(fp string, w http.ResponseWriter, r *http.Request) {
-	mw.Etag(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	mw.Etag(!s.ETagDisabled)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		http.ServeFile(w, r, fp)
 	})).ServeHTTP(w, r)
 }

internal/server/router.go

@@ -69,7 +69,7 @@ func (s *Server) router() http.Handler {
 	// the cache buster randomized string so we can
 	// force reload the assets on each execution
 	assetsPrefix := path.Join(s.PathPrefix, specialPath, s.cacheBuster)
-	r.With(mw.Etag).HandleFunc(path.Join(assetsPrefix, "assets", "*"), s.serveAssets(assetsPrefix))
+	r.With(mw.Etag(!s.ETagDisabled)).HandleFunc(path.Join(assetsPrefix, "assets", "*"), s.serveAssets(assetsPrefix))
 
 	// Create a health check endpoint
 	r.HandleFunc(path.Join(s.PathPrefix, specialPath, "health"), s.healthCheck)

internal/server/server.go

@@ -25,6 +25,7 @@ type Server struct {
 	// Boolean specific settings
 	CorsEnabled        bool
 	HideLinks          bool
+	ETagDisabled       bool
 	DisableCacheBuster bool
 	DisableMarkdown    bool
 	MarkdownBeforeDir  bool

internal/server/startup.go

@@ -14,6 +14,10 @@ func (s *Server) PrintStartup() {
 		fmt.Fprintln(s.LogOutput, startupPrefix, "Path prefix:", s.PathPrefix)
 	}
 
+	if s.ETagDisabled {
+		fmt.Fprintln(s.LogOutput, startupPrefix, "ETag headers disabled")
+	}
+
 	if s.CorsEnabled {
 		fmt.Fprintln(s.LogOutput, startupPrefix, "CORS headers enabled: adding \"Access-Control-Allow-Origin=*\" header")
 	}