forgejo/modules/httpcache/httpcache.go
zeripath 9f5ddca57c
Set the LastModified header for raw files ()
Although the use of LastModified dates for caching of git objects should be
discouraged (as it is not native to git - and there are a LOT of ways this
could be incorrect) - LastModified dates can be a helpful somewhat more human
way of caching for simple cases.

This PR adds this header and handles the If-Modified-Since header to the /raw/
routes.

Fix 

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
2022-05-09 17:54:51 +02:00

122 lines
3.9 KiB
Go

// 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"
"strings"
"time"
"code.gitea.io/gitea/modules/setting"
)
// AddCacheControlToHeader adds suitable cache-control headers to response
func AddCacheControlToHeader(h http.Header, d time.Duration) {
if setting.IsProd {
h.Set("Cache-Control", "private, max-age="+strconv.Itoa(int(d.Seconds())))
} else {
h.Set("Cache-Control", "no-store")
// to remind users they are using non-prod setting.
// some users may be confused by "Cache-Control: no-store" in their setup if they did wrong to `RUN_MODE` in `app.ini`.
h.Add("X-Gitea-Debug", "RUN_MODE="+setting.RunMode)
h.Add("X-Gitea-Debug", "CacheControl=no-store")
}
}
// 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) {
return HandleGenericTimeCache(req, w, fi.ModTime())
}
// HandleGenericTimeCache handles time-based caching for a HTTP request
func HandleGenericTimeCache(req *http.Request, w http.ResponseWriter, lastModified time.Time) (handled bool) {
AddCacheControlToHeader(w.Header(), setting.StaticCacheTime)
ifModifiedSince := req.Header.Get("If-Modified-Since")
if ifModifiedSince != "" {
t, err := time.Parse(http.TimeFormat, ifModifiedSince)
if err == nil && lastModified.Unix() <= t.Unix() {
w.WriteHeader(http.StatusNotModified)
return true
}
}
w.Header().Set("Last-Modified", lastModified.Format(http.TimeFormat))
return false
}
// HandleFileETagCache handles ETag-based caching for a HTTP request
func HandleFileETagCache(req *http.Request, w http.ResponseWriter, fi os.FileInfo) (handled bool) {
etag := generateETag(fi)
return HandleGenericETagCache(req, w, etag)
}
// HandleGenericETagCache handles ETag-based caching for a HTTP request.
// It returns true if the request was handled.
func HandleGenericETagCache(req *http.Request, w http.ResponseWriter, etag string) (handled bool) {
if len(etag) > 0 {
w.Header().Set("Etag", etag)
if checkIfNoneMatchIsValid(req, etag) {
w.WriteHeader(http.StatusNotModified)
return true
}
}
AddCacheControlToHeader(w.Header(), setting.StaticCacheTime)
return false
}
// checkIfNoneMatchIsValid tests if the header If-None-Match matches the ETag
func checkIfNoneMatchIsValid(req *http.Request, etag string) bool {
ifNoneMatch := req.Header.Get("If-None-Match")
if len(ifNoneMatch) > 0 {
for _, item := range strings.Split(ifNoneMatch, ",") {
item = strings.TrimSpace(item)
if item == etag {
return true
}
}
}
return false
}
// HandleGenericETagTimeCache handles ETag-based caching with Last-Modified caching for a HTTP request.
// It returns true if the request was handled.
func HandleGenericETagTimeCache(req *http.Request, w http.ResponseWriter, etag string, lastModified time.Time) (handled bool) {
if len(etag) > 0 {
w.Header().Set("Etag", etag)
}
if !lastModified.IsZero() {
w.Header().Set("Last-Modified", lastModified.Format(http.TimeFormat))
}
if len(etag) > 0 {
if checkIfNoneMatchIsValid(req, etag) {
w.WriteHeader(http.StatusNotModified)
return true
}
}
if !lastModified.IsZero() {
ifModifiedSince := req.Header.Get("If-Modified-Since")
if ifModifiedSince != "" {
t, err := time.Parse(http.TimeFormat, ifModifiedSince)
if err == nil && lastModified.Unix() <= t.Unix() {
w.WriteHeader(http.StatusNotModified)
return true
}
}
}
AddCacheControlToHeader(w.Header(), setting.StaticCacheTime)
return false
}