28fe3db1fb
https://stackoverflow.com/questions/51973120/where-does-the-w-in-an-etag-appear-from https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag# --------- Co-authored-by: delvh <dev.lh@web.de>
100 lines
3.2 KiB
Go
100 lines
3.2 KiB
Go
// Copyright 2020 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package httpcache
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import (
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"io"
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"net/http"
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"strconv"
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"strings"
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"time"
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"code.gitea.io/gitea/modules/setting"
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)
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// SetCacheControlInHeader sets suitable cache-control headers in the response
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func SetCacheControlInHeader(h http.Header, maxAge time.Duration, additionalDirectives ...string) {
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directives := make([]string, 0, 2+len(additionalDirectives))
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// "max-age=0 + must-revalidate" (aka "no-cache") is preferred instead of "no-store"
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// because browsers may restore some input fields after navigate-back / reload a page.
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if setting.IsProd {
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if maxAge == 0 {
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directives = append(directives, "max-age=0", "private", "must-revalidate")
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} else {
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directives = append(directives, "private", "max-age="+strconv.Itoa(int(maxAge.Seconds())))
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}
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} else {
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directives = append(directives, "max-age=0", "private", "must-revalidate")
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// to remind users they are using non-prod setting.
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h.Set("X-Gitea-Debug", "RUN_MODE="+setting.RunMode)
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}
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h.Set("Cache-Control", strings.Join(append(directives, additionalDirectives...), ", "))
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}
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func ServeContentWithCacheControl(w http.ResponseWriter, req *http.Request, name string, modTime time.Time, content io.ReadSeeker) {
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SetCacheControlInHeader(w.Header(), setting.StaticCacheTime)
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http.ServeContent(w, req, name, modTime, content)
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}
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// HandleGenericETagCache handles ETag-based caching for a HTTP request.
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// It returns true if the request was handled.
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func HandleGenericETagCache(req *http.Request, w http.ResponseWriter, etag string) (handled bool) {
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if len(etag) > 0 {
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w.Header().Set("Etag", etag)
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if checkIfNoneMatchIsValid(req, etag) {
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w.WriteHeader(http.StatusNotModified)
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return true
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}
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}
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SetCacheControlInHeader(w.Header(), setting.StaticCacheTime)
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return false
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}
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// checkIfNoneMatchIsValid tests if the header If-None-Match matches the ETag
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func checkIfNoneMatchIsValid(req *http.Request, etag string) bool {
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ifNoneMatch := req.Header.Get("If-None-Match")
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if len(ifNoneMatch) > 0 {
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for _, item := range strings.Split(ifNoneMatch, ",") {
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item = strings.TrimPrefix(strings.TrimSpace(item), "W/") // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag#directives
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if item == etag {
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return true
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}
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}
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}
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return false
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}
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// HandleGenericETagTimeCache handles ETag-based caching with Last-Modified caching for a HTTP request.
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// It returns true if the request was handled.
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func HandleGenericETagTimeCache(req *http.Request, w http.ResponseWriter, etag string, lastModified *time.Time) (handled bool) {
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if len(etag) > 0 {
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w.Header().Set("Etag", etag)
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}
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if lastModified != nil && !lastModified.IsZero() {
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w.Header().Set("Last-Modified", lastModified.Format(http.TimeFormat))
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}
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if len(etag) > 0 {
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if checkIfNoneMatchIsValid(req, etag) {
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w.WriteHeader(http.StatusNotModified)
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return true
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}
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}
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if lastModified != nil && !lastModified.IsZero() {
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ifModifiedSince := req.Header.Get("If-Modified-Since")
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if ifModifiedSince != "" {
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t, err := time.Parse(http.TimeFormat, ifModifiedSince)
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if err == nil && lastModified.Unix() <= t.Unix() {
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w.WriteHeader(http.StatusNotModified)
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return true
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}
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}
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}
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SetCacheControlInHeader(w.Header(), setting.StaticCacheTime)
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return false
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}
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