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// Copyright 2020 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.
package httpcache
import (
"encoding/base64"
"fmt"
"net/http"
"os"
"strconv"
"time"
"code.gitea.io/gitea/modules/setting"
)
// GetCacheControl returns a suitable "Cache-Control" header value
func GetCacheControl() string {
if setting.RunMode == "dev" {
return "no-store"
}
return "private, max-age=" + strconv.FormatInt(int64(setting.StaticCacheTime.Seconds()), 10)
}
// generateETag generates an ETag based on size, filename and file modification time
func generateETag(fi os.FileInfo) string {
etag := fmt.Sprint(fi.Size()) + fi.Name() + fi.ModTime().UTC().Format(http.TimeFormat)
return base64.StdEncoding.EncodeToString([]byte(etag))
}
// HandleTimeCache handles time-based caching for a HTTP request
func HandleTimeCache(req *http.Request, w http.ResponseWriter, fi os.FileInfo) (handled bool) {
ifModifiedSince := req.Header.Get("If-Modified-Since")
if ifModifiedSince != "" {
t, err := time.Parse(http.TimeFormat, ifModifiedSince)
if err == nil && fi.ModTime().Unix() <= t.Unix() {
w.WriteHeader(http.StatusNotModified)
return true
}
}
w.Header().Set("Cache-Control", GetCacheControl())
w.Header().Set("Last-Modified", fi.ModTime().Format(http.TimeFormat))
return false
}
// HandleEtagCache handles ETag-based caching for a HTTP request
func HandleEtagCache(req *http.Request, w http.ResponseWriter, fi os.FileInfo) (handled bool) {
etag := generateETag(fi)
if req.Header.Get("If-None-Match") == etag {
w.WriteHeader(http.StatusNotModified)
return true
}
w.Header().Set("Cache-Control", GetCacheControl())
w.Header().Set("ETag", etag)
return false
}
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