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- // Copyright 2020 The Gitea Authors. All rights reserved.
- // SPDX-License-Identifier: MIT
-
- 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, maxAge time.Duration, additionalDirectives ...string) {
- directives := make([]string, 0, 2+len(additionalDirectives))
-
- // "max-age=0 + must-revalidate" (aka "no-cache") is preferred instead of "no-store"
- // because browsers may restore some input fields after navigate-back / reload a page.
- if setting.IsProd {
- if maxAge == 0 {
- directives = append(directives, "max-age=0", "private", "must-revalidate")
- } else {
- directives = append(directives, "private", "max-age="+strconv.Itoa(int(maxAge.Seconds())))
- }
- } else {
- directives = append(directives, "max-age=0", "private", "must-revalidate")
-
- // to remind users they are using non-prod setting.
- h.Add("X-Gitea-Debug", "RUN_MODE="+setting.RunMode)
- }
-
- h.Set("Cache-Control", strings.Join(append(directives, additionalDirectives...), ", "))
- }
-
- // 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
- }
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