server: add Cache-Control and ETag headers

cmd/gomuks/media.go

@@ -57,7 +57,7 @@ var ErrBadGateway = mautrix.RespError{
 	StatusCode: http.StatusBadGateway,
 }
 
-func (gmx *Gomuks) downloadMediaFromCache(ctx context.Context, w http.ResponseWriter, entry *database.Media, force bool) bool {
+func (gmx *Gomuks) downloadMediaFromCache(ctx context.Context, w http.ResponseWriter, r *http.Request, entry *database.Media, force bool) bool {
 	if !entry.UseCache() {
 		if force {
 			mautrix.MNotFound.WithMessage("Media not found in cache").Write(w)
@@ -69,6 +69,9 @@ func (gmx *Gomuks) downloadMediaFromCache(ctx context.Context, w http.ResponseWr
 		w.Header().Set("Mau-Cached-Error", "true")
 		entry.Error.Write(w)
 		return true
+	} else if r.Header.Get("If-None-Match") == entry.ETag() {
+		w.WriteHeader(http.StatusNotModified)
+		return true
 	}
 	log := zerolog.Ctx(ctx)
 	cacheFile, err := os.Open(gmx.cacheEntryToPath(entry.Hash[:]))
@@ -102,6 +105,8 @@ func cacheEntryToHeaders(w http.ResponseWriter, entry *database.Media) {
 	w.Header().Set("Content-Length", strconv.FormatInt(entry.Size, 10))
 	w.Header().Set("Content-Disposition", mime.FormatMediaType(entry.ContentDisposition(), map[string]string{"filename": entry.FileName}))
 	w.Header().Set("Content-Security-Policy", "sandbox; default-src 'none'; script-src 'none';")
+	w.Header().Set("Cache-Control", "max-age=2592000, immutable")
+	w.Header().Set("ETag", entry.ETag())
 }
 
 type noErrorWriter struct {
@@ -193,7 +198,7 @@ func (gmx *Gomuks) DownloadMedia(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if gmx.downloadMediaFromCache(ctx, w, cacheEntry, false) {
+	if gmx.downloadMediaFromCache(ctx, w, r, cacheEntry, false) {
 		return
 	}
 
@@ -319,7 +324,7 @@ func (gmx *Gomuks) DownloadMedia(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	if w != nil {
-		gmx.downloadMediaFromCache(ctx, w, cacheEntry, true)
+		gmx.downloadMediaFromCache(ctx, w, r, cacheEntry, true)
 	}
 }
 

cmd/gomuks/server.go

@@ -22,6 +22,7 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io/fs"
 	"net/http"
 	_ "net/http/pprof"
@@ -64,7 +65,7 @@ func (gmx *Gomuks) StartServer() {
 	if frontend, err := fs.Sub(web.Frontend, "dist"); err != nil {
 		gmx.Log.Warn().Msg("Frontend not found")
 	} else {
-		router.Handle("/", http.FileServerFS(frontend))
+		router.Handle("/", FrontendCacheMiddleware(http.FileServerFS(frontend)))
 	}
 	gmx.Server = &http.Server{
 		Addr:    gmx.Config.Web.ListenAddress,
@@ -79,6 +80,26 @@ func (gmx *Gomuks) StartServer() {
 	gmx.Log.Info().Str("address", gmx.Config.Web.ListenAddress).Msg("Server started")
 }
 
+func FrontendCacheMiddleware(next http.Handler) http.Handler {
+	var frontendCacheETag string
+	if Commit != "unknown" && !ParsedBuildTime.IsZero() {
+		frontendCacheETag = fmt.Sprintf(`"%s-%s"`, Commit, ParsedBuildTime.Format(time.RFC3339))
+	}
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Header.Get("If-None-Match") == frontendCacheETag {
+			w.WriteHeader(http.StatusNotModified)
+			return
+		}
+		if strings.HasPrefix(r.URL.Path, "/assets/") {
+			w.Header().Set("Cache-Control", "max-age=604800, immutable")
+		}
+		if frontendCacheETag != "" {
+			w.Header().Set("ETag", frontendCacheETag)
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
 var (
 	ErrInvalidHeader = mautrix.RespError{ErrCode: "FI.MAU.GOMUKS.INVALID_HEADER", StatusCode: http.StatusForbidden}
 	ErrMissingCookie = mautrix.RespError{ErrCode: "FI.MAU.GOMUKS.MISSING_COOKIE", Err: "Missing gomuks_auth cookie", StatusCode: http.StatusUnauthorized}

pkg/hicli/database/media.go

@@ -9,6 +9,7 @@ package database
 import (
 	"context"
 	"database/sql"
+	"fmt"
 	"net/http"
 	"slices"
 	"time"
@@ -93,6 +94,8 @@ func (me *MediaError) Write(w http.ResponseWriter) {
 	}
 	me.Matrix.ExtraData["fi.mau.hicli.error_ts"] = me.ReceivedAt.UnixMilli()
 	me.Matrix.ExtraData["fi.mau.hicli.next_retry_ts"] = me.ReceivedAt.Add(me.backoff()).UnixMilli()
+	w.Header().Set("Mau-Errored-At", me.ReceivedAt.Format(http.TimeFormat))
+	w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%d", max(int(time.Until(me.ReceivedAt.Add(me.backoff())).Seconds()), 0)))
 	me.Matrix.WithStatus(me.StatusCode).Write(w)
 }
 
@@ -106,6 +109,13 @@ type Media struct {
 	Error    *MediaError
 }
 
+func (m *Media) ETag() string {
+	if m.Hash == nil {
+		return ""
+	}
+	return fmt.Sprintf(`"%x"`, m.Hash)
+}
+
 func (m *Media) UseCache() bool {
 	return m != nil && (m.Hash != nil || m.Error.UseCache())
 }