Fix mime-type detection for HTTP server (#18370)

Bypass the unstable behavior of Golang's mime.TypeByExtension

modules/public/serve_static.go

@@ -0,0 +1,82 @@
+// Copyright 2016 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+//go:build bindata
+// +build bindata
+
+package public
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+// GlobalModTime provide a global mod time for embedded asset files
+func GlobalModTime(filename string) time.Time {
+	return timeutil.GetExecutableModTime()
+}
+
+func fileSystem(dir string) http.FileSystem {
+	return Assets
+}
+
+func Asset(name string) ([]byte, error) {
+	f, err := Assets.Open("/" + name)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return io.ReadAll(f)
+}
+
+func AssetNames() []string {
+	realFS := Assets.(vfsgen۰FS)
+	results := make([]string, 0, len(realFS))
+	for k := range realFS {
+		results = append(results, k[1:])
+	}
+	return results
+}
+
+func AssetIsDir(name string) (bool, error) {
+	if f, err := Assets.Open("/" + name); err != nil {
+		return false, err
+	} else {
+		defer f.Close()
+		if fi, err := f.Stat(); err != nil {
+			return false, err
+		} else {
+			return fi.IsDir(), nil
+		}
+	}
+}
+
+// serveContent serve http content
+func serveContent(w http.ResponseWriter, req *http.Request, fi os.FileInfo, modtime time.Time, content io.ReadSeeker) {
+	encodings := parseAcceptEncoding(req.Header.Get("Accept-Encoding"))
+	if encodings["gzip"] {
+		if cf, ok := fi.(*vfsgen۰CompressedFileInfo); ok {
+			rdGzip := bytes.NewReader(cf.GzipBytes())
+			// all static files are managed by Gitea, so we can make sure every file has the correct ext name
+			// then we can get the correct Content-Type, we do not need to do http.DetectContentType on the decompressed data
+			mimeType := detectWellKnownMimeType(filepath.Ext(fi.Name()))
+			if mimeType == "" {
+				mimeType = "application/octet-stream"
+			}
+			w.Header().Set("Content-Type", mimeType)
+			w.Header().Set("Content-Encoding", "gzip")
+			http.ServeContent(w, req, fi.Name(), modtime, rdGzip)
+			return
+		}
+	}
+
+	http.ServeContent(w, req, fi.Name(), modtime, content)
+	return
+}