Redo direct media access with URL refreshing (#135)

attachments.go

@@ -323,19 +323,17 @@ func (br *DiscordBridge) copyAttachmentToMatrix(intent *appservice.IntentAPI, ur
 }
 
 func (portal *Portal) getEmojiMXCByDiscordID(emojiID, name string, animated bool) id.ContentURI {
-	var url, mimeType, ext string
+	mxc := portal.bridge.DMA.EmojiMXC(emojiID, name, animated)
+	if !mxc.IsEmpty() {
+		return mxc
+	}
+	var url, mimeType string
 	if animated {
 		url = discordgo.EndpointEmojiAnimated(emojiID)
 		mimeType = "image/gif"
-		ext = "gif"
 	} else {
 		url = discordgo.EndpointEmoji(emojiID)
 		mimeType = "image/png"
-		ext = "png"
-	}
-	mxc := portal.bridge.Config.Bridge.MediaPatterns.Emoji(emojiID, ext)
-	if !mxc.IsEmpty() {
-		return mxc
 	}
 	dbFile, err := portal.bridge.copyAttachmentToMatrix(portal.MainIntent(), url, false, AttachmentMeta{
 		AttachmentID: emojiID,

config/bridge.go

@@ -25,7 +25,6 @@ import (
 	"github.com/bwmarrin/discordgo"
 
 	"maunium.net/go/mautrix/bridge/bridgeconfig"
-	"maunium.net/go/mautrix/id"
 )
 
 type BridgeConfig struct {
@@ -55,8 +54,8 @@ type BridgeConfig struct {
 	EnableWebhookAvatars        bool `yaml:"enable_webhook_avatars"`
 	UseDiscordCDNUpload         bool `yaml:"use_discord_cdn_upload"`
 
-	CacheMedia    string        `yaml:"cache_media"`
+	CacheMedia  string      `yaml:"cache_media"`
-	MediaPatterns MediaPatterns `yaml:"media_patterns"`
+	DirectMedia DirectMedia `yaml:"direct_media"`
 
 	AnimatedSticker struct {
 		Target string `yaml:"target"`
@@ -96,111 +95,12 @@ type BridgeConfig struct {
 	guildNameTemplate   *template.Template `yaml:"-"`
 }
 
-type MediaPatterns struct {
+type DirectMedia struct {
-	Enabled        bool   `yaml:"enabled"`
+	Enabled           bool   `yaml:"enabled"`
-	TplAttachments string `yaml:"attachments"`
+	ServerName        string `yaml:"server_name"`
-	TplEmojis      string `yaml:"emojis"`
+	WellKnownResponse string `yaml:"well_known_response"`
-	TplStickers    string `yaml:"stickers"`
+	AllowProxy        bool   `yaml:"allow_proxy"`
-	TplAvatars     string `yaml:"avatars"`
+	ServerKey         string `yaml:"server_key"`
-
-	attachments *template.Template `yaml:"-"`
-	emojis      *template.Template `yaml:"-"`
-	stickers    *template.Template `yaml:"-"`
-	avatars     *template.Template `yaml:"-"`
-}
-
-type umMediaPatterns MediaPatterns
-
-func (mp *MediaPatterns) UnmarshalYAML(unmarshal func(interface{}) error) error {
-	err := unmarshal((*umMediaPatterns)(mp))
-	if err != nil {
-		return err
-	}
-	tpl := template.New("media_patterns")
-
-	pairs := []struct {
-		ptr      **template.Template
-		name     string
-		template string
-	}{
-		{&mp.attachments, "attachments", mp.TplAttachments},
-		{&mp.emojis, "emojis", mp.TplEmojis},
-		{&mp.stickers, "stickers", mp.TplStickers},
-		{&mp.avatars, "avatars", mp.TplAvatars},
-	}
-	for _, pair := range pairs {
-		if pair.template == "" {
-			continue
-		}
-		*pair.ptr, err = tpl.New(pair.name).Parse(pair.template)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
-type attachmentParams struct {
-	ChannelID    string
-	AttachmentID string
-	FileName     string
-}
-
-type emojiStickerParams struct {
-	ID  string
-	Ext string
-}
-
-type avatarParams struct {
-	UserID   string
-	AvatarID string
-	Ext      string
-}
-
-func (mp *MediaPatterns) execute(tpl *template.Template, params any) id.ContentURI {
-	if tpl == nil || !mp.Enabled {
-		return id.ContentURI{}
-	}
-	var out strings.Builder
-	err := tpl.Execute(&out, params)
-	if err != nil {
-		panic(err)
-	}
-	uri, err := id.ParseContentURI(out.String())
-	if err != nil {
-		panic(err)
-	}
-	return uri
-}
-
-func (mp *MediaPatterns) Attachment(channelID, attachmentID, filename string) id.ContentURI {
-	return mp.execute(mp.attachments, attachmentParams{
-		ChannelID:    channelID,
-		AttachmentID: attachmentID,
-		FileName:     filename,
-	})
-}
-
-func (mp *MediaPatterns) Emoji(emojiID, ext string) id.ContentURI {
-	return mp.execute(mp.emojis, emojiStickerParams{
-		ID:  emojiID,
-		Ext: ext,
-	})
-}
-
-func (mp *MediaPatterns) Sticker(stickerID, ext string) id.ContentURI {
-	return mp.execute(mp.stickers, emojiStickerParams{
-		ID:  stickerID,
-		Ext: ext,
-	})
-}
-
-func (mp *MediaPatterns) Avatar(userID, avatarID, ext string) id.ContentURI {
-	return mp.execute(mp.avatars, avatarParams{
-		UserID:   userID,
-		AvatarID: avatarID,
-		Ext:      ext,
-	})
 }
 
 type BackfillLimitPart struct {

config/upgrade.go

@@ -20,6 +20,7 @@ import (
 	up "go.mau.fi/util/configupgrade"
 	"go.mau.fi/util/random"
 	"maunium.net/go/mautrix/bridge/bridgeconfig"
+	"maunium.net/go/mautrix/federation"
 )
 
 func DoUpgrade(helper *up.Helper) {
@@ -58,12 +59,17 @@ func DoUpgrade(helper *up.Helper) {
 	helper.Copy(up.Bool, "bridge", "prefix_webhook_messages")
 	helper.Copy(up.Bool, "bridge", "enable_webhook_avatars")
 	helper.Copy(up.Bool, "bridge", "use_discord_cdn_upload")
-	helper.Copy(up.Bool, "bridge", "media_patterns", "enabled")
 	helper.Copy(up.Str, "bridge", "cache_media")
-	helper.Copy(up.Str|up.Null, "bridge", "media_patterns", "attachments")
+	helper.Copy(up.Bool, "bridge", "direct_media", "enabled")
-	helper.Copy(up.Str|up.Null, "bridge", "media_patterns", "emojis")
+	helper.Copy(up.Str, "bridge", "direct_media", "server_name")
-	helper.Copy(up.Str|up.Null, "bridge", "media_patterns", "stickers")
+	helper.Copy(up.Str|up.Null, "bridge", "direct_media", "well_known_response")
-	helper.Copy(up.Str|up.Null, "bridge", "media_patterns", "avatars")
+	helper.Copy(up.Bool, "bridge", "direct_media", "allow_proxy")
+	if serverKey, ok := helper.Get(up.Str, "bridge", "direct_media", "server_key"); !ok || serverKey == "generate" {
+		serverKey = federation.GenerateSigningKey().SynapseString()
+		helper.Set(up.Str, serverKey, "bridge", "direct_media", "server_key")
+	} else {
+		helper.Copy(up.Str, "bridge", "direct_media", "server_key")
+	}
 	helper.Copy(up.Str, "bridge", "animated_sticker", "target")
 	helper.Copy(up.Int, "bridge", "animated_sticker", "args", "width")
 	helper.Copy(up.Int, "bridge", "animated_sticker", "args", "height")

database/userportal.go

@@ -7,6 +7,7 @@ import (
 
 	"go.mau.fi/util/dbutil"
 	log "maunium.net/go/maulogger/v2"
+	"maunium.net/go/mautrix/id"
 )
 
 const (
@@ -44,6 +45,24 @@ func (u *User) scanUserPortals(rows dbutil.Rows) []UserPortal {
 	return ups
 }
 
+func (db *Database) GetUsersInPortal(channelID string) []id.UserID {
+	rows, err := db.Query("SELECT user_mxid FROM user_portal WHERE discord_id=$1", channelID)
+	if err != nil {
+		db.Portal.log.Errorln("Failed to get users in portal:", err)
+	}
+	var users []id.UserID
+	for rows.Next() {
+		var mxid id.UserID
+		err = rows.Scan(&mxid)
+		if err != nil {
+			db.Portal.log.Errorln("Failed to scan user in portal:", err)
+		} else {
+			users = append(users, mxid)
+		}
+	}
+	return users
+}
+
 func (u *User) GetPortals() []UserPortal {
 	rows, err := u.db.Query("SELECT discord_id, type, timestamp, in_space FROM user_portal WHERE user_mxid=$1", u.MXID)
 	if err != nil {

directmedia.go

@@ -0,0 +1,570 @@
+// mautrix-discord - A Matrix-Discord puppeting bridge.
+// Copyright (C) 2024 Tulir Asokan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"mime"
+	"net"
+	"net/http"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/bwmarrin/discordgo"
+	"github.com/gorilla/mux"
+	"github.com/rs/zerolog"
+	"maunium.net/go/mautrix"
+	"maunium.net/go/mautrix/federation"
+	"maunium.net/go/mautrix/id"
+
+	"go.mau.fi/mautrix-discord/config"
+)
+
+type DirectMediaAPI struct {
+	bridge *DiscordBridge
+	ks     *federation.KeyServer
+	cfg    config.DirectMedia
+	log    zerolog.Logger
+	proxy  http.Client
+
+	signatureKey [32]byte
+
+	attachmentCache     map[AttachmentCacheKey]AttachmentCacheValue
+	attachmentCacheLock sync.Mutex
+}
+
+type AttachmentCacheKey struct {
+	ChannelID    uint64
+	AttachmentID uint64
+}
+
+type AttachmentCacheValue struct {
+	URL    string
+	Expiry time.Time
+}
+
+func newDirectMediaAPI(br *DiscordBridge) *DirectMediaAPI {
+	if !br.Config.Bridge.DirectMedia.Enabled {
+		return nil
+	}
+	dma := &DirectMediaAPI{
+		bridge: br,
+		cfg:    br.Config.Bridge.DirectMedia,
+		log:    br.ZLog.With().Str("component", "direct media").Logger(),
+		proxy: http.Client{
+			Transport: &http.Transport{
+				DialContext:         (&net.Dialer{Timeout: 10 * time.Second}).DialContext,
+				TLSHandshakeTimeout: 10 * time.Second,
+				ForceAttemptHTTP2:   false,
+			},
+			Timeout: 60 * time.Second,
+		},
+		attachmentCache: make(map[AttachmentCacheKey]AttachmentCacheValue),
+	}
+	r := br.AS.Router
+
+	parsed, err := federation.ParseSynapseKey(dma.cfg.ServerKey)
+	if err != nil {
+		dma.log.WithLevel(zerolog.FatalLevel).Err(err).Msg("Failed to parse server key")
+		os.Exit(11)
+		return nil
+	}
+	dma.signatureKey = sha256.Sum256(parsed.Priv.Seed())
+	dma.ks = &federation.KeyServer{
+		KeyProvider: &federation.StaticServerKey{
+			ServerName: dma.cfg.ServerName,
+			Key:        parsed,
+		},
+		WellKnownTarget: dma.cfg.WellKnownResponse,
+		Version: federation.ServerVersion{
+			Name:    br.Name,
+			Version: br.Version,
+		},
+	}
+	if dma.ks.WellKnownTarget == "" {
+		dma.ks.WellKnownTarget = fmt.Sprintf("%s:443", dma.cfg.ServerName)
+	}
+	mediaRouter := r.PathPrefix("/_matrix/media").Subrouter()
+	var reqIDCounter atomic.Uint64
+	mediaRouter.Use(func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Access-Control-Allow-Origin", "*")
+			w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
+			w.Header().Set("Access-Control-Allow-Headers", "X-Requested-With, Content-Type, Authorization")
+			log := dma.log.With().
+				Str("remote_addr", r.RemoteAddr).
+				Str("request_path", r.URL.Path).
+				Uint64("req_id", reqIDCounter.Add(1)).
+				Logger()
+			next.ServeHTTP(w, r.WithContext(log.WithContext(r.Context())))
+		})
+	})
+	addRoutes := func(version string) {
+		mediaRouter.HandleFunc("/"+version+"/download/{serverName}/{mediaID}", dma.DownloadMedia).Methods(http.MethodGet)
+		mediaRouter.HandleFunc("/"+version+"/download/{serverName}/{mediaID}/{fileName}", dma.DownloadMedia).Methods(http.MethodGet)
+		mediaRouter.HandleFunc("/"+version+"/thumbnail/{serverName}/{mediaID}", dma.DownloadMedia).Methods(http.MethodGet)
+		mediaRouter.HandleFunc("/"+version+"/upload/{serverName}/{mediaID}", dma.UploadNotSupported).Methods(http.MethodPut)
+		mediaRouter.HandleFunc("/"+version+"/upload", dma.UploadNotSupported).Methods(http.MethodPost)
+		mediaRouter.HandleFunc("/"+version+"/config", dma.UploadNotSupported).Methods(http.MethodGet)
+		mediaRouter.HandleFunc("/"+version+"/preview_url", dma.PreviewURLNotSupported).Methods(http.MethodGet)
+	}
+	addRoutes("v3")
+	addRoutes("r0")
+	addRoutes("v1")
+	mediaRouter.NotFoundHandler = http.HandlerFunc(dma.UnknownEndpoint)
+	mediaRouter.MethodNotAllowedHandler = http.HandlerFunc(dma.UnsupportedMethod)
+	dma.ks.Register(r)
+
+	return dma
+}
+
+func (dma *DirectMediaAPI) makeMXC(data MediaIDData) id.ContentURI {
+	return id.ContentURI{
+		Homeserver: dma.cfg.ServerName,
+		FileID:     data.Wrap().SignedString(dma.signatureKey),
+	}
+}
+
+func (dma *DirectMediaAPI) addAttachmentToCache(channelID uint64, att *discordgo.MessageAttachment) {
+	attachmentID, err := strconv.ParseUint(att.ID, 10, 64)
+	if err != nil {
+		return
+	}
+	dma.attachmentCache[AttachmentCacheKey{
+		ChannelID:    channelID,
+		AttachmentID: attachmentID,
+	}] = AttachmentCacheValue{
+		URL: att.URL,
+		// TODO find expiry somehow properly?
+		Expiry: time.Now().Add(23 * time.Hour),
+	}
+}
+
+func (dma *DirectMediaAPI) AttachmentMXC(channelID, messageID string, att *discordgo.MessageAttachment) (mxc id.ContentURI) {
+	if dma == nil {
+		return
+	}
+	channelIDInt, err := strconv.ParseUint(channelID, 10, 64)
+	if err != nil {
+		dma.log.Warn().Str("channel_id", channelID).Msg("Got non-integer channel ID")
+		return
+	}
+	messageIDInt, err := strconv.ParseUint(messageID, 10, 64)
+	if err != nil {
+		dma.log.Warn().Str("message_id", messageID).Msg("Got non-integer message ID")
+		return
+	}
+	attachmentIDInt, err := strconv.ParseUint(att.ID, 10, 64)
+	if err != nil {
+		dma.log.Warn().Str("attachment_id", att.ID).Msg("Got non-integer attachment ID")
+		return
+	}
+	dma.attachmentCacheLock.Lock()
+	dma.addAttachmentToCache(channelIDInt, att)
+	dma.attachmentCacheLock.Unlock()
+	return dma.makeMXC(&AttachmentMediaData{
+		ChannelID:    channelIDInt,
+		MessageID:    messageIDInt,
+		AttachmentID: attachmentIDInt,
+	})
+}
+
+func (dma *DirectMediaAPI) EmojiMXC(emojiID, name string, animated bool) (mxc id.ContentURI) {
+	if dma == nil {
+		return
+	}
+	emojiIDInt, err := strconv.ParseUint(emojiID, 10, 64)
+	if err != nil {
+		dma.log.Warn().Str("emoji_id", emojiID).Msg("Got non-integer emoji ID")
+		return
+	}
+	return dma.makeMXC(&EmojiMediaData{
+		EmojiMediaDataInner: EmojiMediaDataInner{
+			EmojiID:  emojiIDInt,
+			Animated: animated,
+		},
+		Name: name,
+	})
+}
+
+func (dma *DirectMediaAPI) StickerMXC(stickerID string, format discordgo.StickerFormat) (mxc id.ContentURI) {
+	if dma == nil {
+		return
+	}
+	stickerIDInt, err := strconv.ParseUint(stickerID, 10, 64)
+	if err != nil {
+		dma.log.Warn().Str("sticker_id", stickerID).Msg("Got non-integer sticker ID")
+		return
+	} else if format > 255 || format < 0 {
+		dma.log.Warn().Int("format", int(format)).Msg("Got invalid sticker format")
+		return
+	}
+	return dma.makeMXC(&StickerMediaData{
+		StickerID: stickerIDInt,
+		Format:    byte(format),
+	})
+}
+
+func (dma *DirectMediaAPI) AvatarMXC(guildID, userID, avatarID string) (mxc id.ContentURI) {
+	if dma == nil {
+		return
+	}
+	animated := strings.HasPrefix(avatarID, "a_")
+	avatarIDBytes, err := hex.DecodeString(strings.TrimPrefix(avatarID, "a_"))
+	if err != nil {
+		dma.log.Warn().Str("avatar_id", avatarID).Msg("Got non-hex avatar ID")
+		return
+	} else if len(avatarIDBytes) != 16 {
+		dma.log.Warn().Str("avatar_id", avatarID).Msg("Got invalid avatar ID length")
+		return
+	}
+	avatarIDArray := [16]byte(avatarIDBytes)
+	userIDInt, err := strconv.ParseUint(userID, 10, 64)
+	if err != nil {
+		dma.log.Warn().Str("user_id", userID).Msg("Got non-integer user ID")
+		return
+	}
+	if guildID != "" {
+		guildIDInt, err := strconv.ParseUint(guildID, 10, 64)
+		if err != nil {
+			dma.log.Warn().Str("guild_id", guildID).Msg("Got non-integer guild ID")
+			return
+		}
+		return dma.makeMXC(&GuildMemberAvatarMediaData{
+			GuildID:  guildIDInt,
+			UserID:   userIDInt,
+			AvatarID: avatarIDArray,
+			Animated: animated,
+		})
+	} else {
+		return dma.makeMXC(&UserAvatarMediaData{
+			UserID:   userIDInt,
+			AvatarID: avatarIDArray,
+			Animated: animated,
+		})
+	}
+}
+
+type RespError struct {
+	Code    string
+	Message string
+	Status  int
+}
+
+func (re *RespError) Error() string {
+	return re.Message
+}
+
+var ErrNoUsersWithAccessFound = errors.New("no users found to fetch message")
+var ErrAttachmentNotFound = errors.New("attachment not found")
+
+func (dma *DirectMediaAPI) fetchNewAttachmentURL(ctx context.Context, meta *AttachmentMediaData) (string, error) {
+	var client *discordgo.Session
+	channelIDStr := strconv.FormatUint(meta.ChannelID, 10)
+	users := dma.bridge.DB.GetUsersInPortal(channelIDStr)
+	for _, userID := range users {
+		user := dma.bridge.GetCachedUserByMXID(userID)
+		if user != nil && user.Session != nil {
+			client = user.Session
+			if !client.IsUser {
+				break
+			}
+		}
+	}
+	if client == nil {
+		return "", ErrNoUsersWithAccessFound
+	}
+	var url string
+	var msgs []*discordgo.Message
+	var err error
+	messageIDStr := strconv.FormatUint(meta.MessageID, 10)
+	if client.IsUser {
+		msgs, err = client.ChannelMessages(channelIDStr, 5, "", "", messageIDStr)
+	} else {
+		var msg *discordgo.Message
+		msg, err = client.ChannelMessage(channelIDStr, messageIDStr)
+		msgs = []*discordgo.Message{msg}
+	}
+	if err != nil {
+		return "", fmt.Errorf("failed to fetch message: %w", err)
+	}
+	attachmentIDStr := strconv.FormatUint(meta.AttachmentID, 10)
+	for _, item := range msgs {
+		for _, att := range item.Attachments {
+			dma.addAttachmentToCache(meta.ChannelID, att)
+			if att.ID == attachmentIDStr {
+				url = att.URL
+			}
+		}
+	}
+	if url == "" {
+		return "", ErrAttachmentNotFound
+	}
+	return url, nil
+}
+
+func (dma *DirectMediaAPI) GetEmojiInfo(contentURI id.ContentURI) *EmojiMediaData {
+	if dma == nil || contentURI.IsEmpty() || contentURI.Homeserver != dma.cfg.ServerName {
+		return nil
+	}
+	mediaID, err := ParseMediaID(contentURI.FileID, dma.signatureKey)
+	if err != nil {
+		return nil
+	}
+	emojiData, ok := mediaID.Data.(*EmojiMediaData)
+	if !ok {
+		return nil
+	}
+	return emojiData
+
+}
+
+func (dma *DirectMediaAPI) getMediaURL(ctx context.Context, encodedMediaID string) (url string, expiry time.Time, err error) {
+	var mediaID *MediaID
+	mediaID, err = ParseMediaID(encodedMediaID, dma.signatureKey)
+	if err != nil {
+		err = &RespError{
+			Code:    mautrix.MNotFound.ErrCode,
+			Message: err.Error(),
+			Status:  http.StatusNotFound,
+		}
+		return
+	}
+	switch mediaData := mediaID.Data.(type) {
+	case *AttachmentMediaData:
+		dma.attachmentCacheLock.Lock()
+		defer dma.attachmentCacheLock.Unlock()
+		cached, ok := dma.attachmentCache[mediaData.CacheKey()]
+		if ok && time.Until(cached.Expiry) > 5*time.Minute {
+			return cached.URL, cached.Expiry, nil
+		}
+		zerolog.Ctx(ctx).Debug().
+			Uint64("channel_id", mediaData.ChannelID).
+			Uint64("message_id", mediaData.MessageID).
+			Uint64("attachment_id", mediaData.AttachmentID).
+			Msg("Refreshing attachment URL")
+		url, err = dma.fetchNewAttachmentURL(ctx, mediaData)
+		if err != nil {
+			zerolog.Ctx(ctx).Err(err).Msg("Failed to refresh attachment URL")
+			msg := "Failed to refresh attachment URL"
+			if errors.Is(err, ErrNoUsersWithAccessFound) {
+				msg = "No users found with access to the channel"
+			} else if errors.Is(err, ErrAttachmentNotFound) {
+				msg = "Attachment not found in message. Perhaps it was deleted?"
+			}
+			err = &RespError{
+				Code:    mautrix.MNotFound.ErrCode,
+				Message: msg,
+				Status:  http.StatusNotFound,
+			}
+		} else {
+			zerolog.Ctx(ctx).Debug().Msg("Successfully refreshed attachment URL")
+			// TODO find expiry somehow properly?
+			expiry = time.Now().Add(23 * time.Hour)
+		}
+	case *EmojiMediaData:
+		if mediaData.Animated {
+			url = discordgo.EndpointEmojiAnimated(strconv.FormatUint(mediaData.EmojiID, 10))
+		} else {
+			url = discordgo.EndpointEmoji(strconv.FormatUint(mediaData.EmojiID, 10))
+		}
+	case *StickerMediaData:
+		url = discordgo.EndpointStickerImage(
+			strconv.FormatUint(mediaData.StickerID, 10),
+			discordgo.StickerFormat(mediaData.Format),
+		)
+	case *UserAvatarMediaData:
+		if mediaData.Animated {
+			url = discordgo.EndpointUserAvatarAnimated(
+				strconv.FormatUint(mediaData.UserID, 10),
+				fmt.Sprintf("a_%x", mediaData.AvatarID),
+			)
+		} else {
+			url = discordgo.EndpointUserAvatar(
+				strconv.FormatUint(mediaData.UserID, 10),
+				fmt.Sprintf("%x", mediaData.AvatarID),
+			)
+		}
+	case *GuildMemberAvatarMediaData:
+		if mediaData.Animated {
+			url = discordgo.EndpointGuildMemberAvatarAnimated(
+				strconv.FormatUint(mediaData.GuildID, 10),
+				strconv.FormatUint(mediaData.UserID, 10),
+				fmt.Sprintf("a_%x", mediaData.AvatarID),
+			)
+		} else {
+			url = discordgo.EndpointGuildMemberAvatar(
+				strconv.FormatUint(mediaData.GuildID, 10),
+				strconv.FormatUint(mediaData.UserID, 10),
+				fmt.Sprintf("%x", mediaData.AvatarID),
+			)
+		}
+	default:
+		zerolog.Ctx(ctx).Error().Type("media_data_type", mediaData).Msg("Unrecognized media data struct")
+		err = &RespError{
+			Code:    "M_UNKNOWN",
+			Message: "Unrecognized media data struct",
+			Status:  http.StatusInternalServerError,
+		}
+	}
+	return
+}
+
+func (dma *DirectMediaAPI) proxyDownload(ctx context.Context, w http.ResponseWriter, url, fileName string) {
+	log := zerolog.Ctx(ctx)
+	req, err := http.NewRequest(http.MethodGet, url, nil)
+	if err != nil {
+		log.Err(err).Str("url", url).Msg("Failed to create proxy request")
+		jsonResponse(w, http.StatusInternalServerError, &mautrix.RespError{
+			ErrCode: "M_UNKNOWN",
+			Err:     "Failed to create proxy request",
+		})
+		return
+	}
+	for key, val := range discordgo.DroidDownloadHeaders {
+		req.Header.Set(key, val)
+	}
+	resp, err := dma.proxy.Do(req)
+	defer func() {
+		if resp != nil && resp.Body != nil {
+			_ = resp.Body.Close()
+		}
+	}()
+	if err != nil {
+		log.Err(err).Str("url", url).Msg("Failed to proxy download")
+		jsonResponse(w, http.StatusServiceUnavailable, &mautrix.RespError{
+			ErrCode: "M_UNKNOWN",
+			Err:     "Failed to proxy download",
+		})
+		return
+	} else if resp.StatusCode != http.StatusOK {
+		log.Warn().Str("url", url).Int("status", resp.StatusCode).Msg("Unexpected status code proxying download")
+		jsonResponse(w, resp.StatusCode, &mautrix.RespError{
+			ErrCode: "M_UNKNOWN",
+			Err:     "Unexpected status code proxying download",
+		})
+		return
+	}
+	w.Header()["Content-Type"] = resp.Header["Content-Type"]
+	w.Header()["Content-Length"] = resp.Header["Content-Length"]
+	w.Header()["Last-Modified"] = resp.Header["Last-Modified"]
+	w.Header()["Cache-Control"] = resp.Header["Cache-Control"]
+	contentDisposition := "attachment"
+	switch resp.Header.Get("Content-Type") {
+	case "text/css", "text/plain", "text/csv", "application/json", "application/ld+json", "image/jpeg", "image/gif",
+		"image/png", "image/apng", "image/webp", "image/avif", "video/mp4", "video/webm", "video/ogg", "video/quicktime",
+		"audio/mp4", "audio/webm", "audio/aac", "audio/mpeg", "audio/ogg", "audio/wave", "audio/wav", "audio/x-wav",
+		"audio/x-pn-wav", "audio/flac", "audio/x-flac", "application/pdf":
+		contentDisposition = "inline"
+	}
+	if fileName != "" {
+		contentDisposition = mime.FormatMediaType(contentDisposition, map[string]string{
+			"filename": fileName,
+		})
+	}
+	w.Header().Set("Content-Disposition", contentDisposition)
+	w.WriteHeader(http.StatusOK)
+	_, err = io.Copy(w, resp.Body)
+	if err != nil {
+		log.Debug().Err(err).Msg("Failed to write proxy response")
+	}
+}
+
+func (dma *DirectMediaAPI) DownloadMedia(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	log := zerolog.Ctx(ctx)
+	vars := mux.Vars(r)
+	if vars["serverName"] != dma.cfg.ServerName {
+		jsonResponse(w, http.StatusNotFound, &mautrix.RespError{
+			ErrCode: mautrix.MNotFound.ErrCode,
+			Err:     fmt.Sprintf("This is a Discord media proxy for %q, other media downloads are not available here", dma.cfg.ServerName),
+		})
+		return
+	}
+	url, expiresAt, err := dma.getMediaURL(ctx, vars["mediaID"])
+	if err != nil {
+		var respError *RespError
+		if errors.As(err, &respError) {
+			jsonResponse(w, respError.Status, &mautrix.RespError{
+				ErrCode: respError.Code,
+				Err:     respError.Message,
+			})
+		} else {
+			log.Err(err).Str("media_id", vars["mediaID"]).Msg("Failed to get media URL")
+			jsonResponse(w, http.StatusNotFound, &mautrix.RespError{
+				ErrCode: mautrix.MNotFound.ErrCode,
+				Err:     "Media not found",
+			})
+		}
+		return
+
+	}
+	// Proxy if the config allows proxying and the request doesn't allow redirects.
+	// In any other case, redirect to the Discord CDN.
+	if dma.cfg.AllowProxy && r.URL.Query().Get("allow_redirect") != "true" {
+		dma.proxyDownload(ctx, w, url, vars["fileName"])
+		return
+	}
+	w.Header().Set("Location", url)
+	expirySeconds := (time.Until(expiresAt) - 5*time.Minute).Seconds()
+	if expiresAt.IsZero() {
+		w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
+	} else if expirySeconds > 0 {
+		cacheControl := fmt.Sprintf("public, max-age=%d, immutable", int(expirySeconds))
+		w.Header().Set("Cache-Control", cacheControl)
+	} else {
+		w.Header().Set("Cache-Control", "no-store")
+	}
+	w.WriteHeader(http.StatusTemporaryRedirect)
+}
+
+func (dma *DirectMediaAPI) UploadNotSupported(w http.ResponseWriter, r *http.Request) {
+	jsonResponse(w, http.StatusNotImplemented, &mautrix.RespError{
+		ErrCode: mautrix.MUnrecognized.ErrCode,
+		Err:     "This bridge only supports proxying Discord media downloads and does not support media uploads.",
+	})
+}
+
+func (dma *DirectMediaAPI) PreviewURLNotSupported(w http.ResponseWriter, r *http.Request) {
+	jsonResponse(w, http.StatusNotImplemented, &mautrix.RespError{
+		ErrCode: mautrix.MUnrecognized.ErrCode,
+		Err:     "This bridge only supports proxying Discord media downloads and does not support URL previews.",
+	})
+}
+
+func (dma *DirectMediaAPI) UnknownEndpoint(w http.ResponseWriter, r *http.Request) {
+	jsonResponse(w, http.StatusNotFound, &mautrix.RespError{
+		ErrCode: mautrix.MUnrecognized.ErrCode,
+		Err:     "Unrecognized endpoint",
+	})
+}
+
+func (dma *DirectMediaAPI) UnsupportedMethod(w http.ResponseWriter, r *http.Request) {
+	jsonResponse(w, http.StatusMethodNotAllowed, &mautrix.RespError{
+		ErrCode: mautrix.MUnrecognized.ErrCode,
+		Err:     "Invalid method for endpoint",
+	})
+}

directmedia_id.go

@@ -0,0 +1,287 @@
+// mautrix-discord - A Matrix-Discord puppeting bridge.
+// Copyright (C) 2024 Tulir Asokan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+)
+
+const MediaIDPrefix = "\U0001F408DISCORD"
+const MediaIDVersion = 1
+
+type MediaIDClass uint8
+
+const (
+	MediaIDClassAttachment        MediaIDClass = 1
+	MediaIDClassEmoji             MediaIDClass = 2
+	MediaIDClassSticker           MediaIDClass = 3
+	MediaIDClassUserAvatar        MediaIDClass = 4
+	MediaIDClassGuildMemberAvatar MediaIDClass = 5
+)
+
+type MediaIDData interface {
+	Write(to io.Writer)
+	Read(from io.Reader) error
+	Size() int
+	Wrap() *MediaID
+}
+
+type MediaID struct {
+	Version   uint8
+	TypeClass MediaIDClass
+	Data      MediaIDData
+}
+
+func ParseMediaID(id string, key [32]byte) (*MediaID, error) {
+	data, err := base64.RawURLEncoding.DecodeString(id)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode base64: %w", err)
+	}
+	hasher := hmac.New(sha256.New, key[:])
+	checksum := data[len(data)-TruncatedHashLength:]
+	data = data[:len(data)-TruncatedHashLength]
+	hasher.Write(data)
+	if !hmac.Equal(checksum, hasher.Sum(nil)[:TruncatedHashLength]) {
+		return nil, ErrMediaIDChecksumMismatch
+	}
+	mid := &MediaID{}
+	err = mid.Read(bytes.NewReader(data))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse media ID: %w", err)
+	}
+	return mid, nil
+}
+
+const TruncatedHashLength = 16
+
+func (mid *MediaID) SignedString(key [32]byte) string {
+	buf := bytes.NewBuffer(make([]byte, 0, mid.Size()))
+	mid.Write(buf)
+	hasher := hmac.New(sha256.New, key[:])
+	hasher.Write(buf.Bytes())
+	buf.Write(hasher.Sum(nil)[:TruncatedHashLength])
+	return base64.RawURLEncoding.EncodeToString(buf.Bytes())
+}
+
+func (mid *MediaID) Write(to io.Writer) {
+	_, _ = to.Write([]byte(MediaIDPrefix))
+	_ = binary.Write(to, binary.BigEndian, mid.Version)
+	_ = binary.Write(to, binary.BigEndian, mid.TypeClass)
+	mid.Data.Write(to)
+}
+
+func (mid *MediaID) Size() int {
+	return len(MediaIDPrefix) + 2 + mid.Data.Size() + TruncatedHashLength
+}
+
+var (
+	ErrInvalidMediaID          = errors.New("invalid media ID")
+	ErrMediaIDChecksumMismatch = errors.New("invalid checksum in media ID")
+	ErrUnsupportedMediaID      = errors.New("unsupported media ID")
+)
+
+func (mid *MediaID) Read(from io.Reader) error {
+	prefix := make([]byte, len(MediaIDPrefix))
+	_, err := io.ReadFull(from, prefix)
+	if err != nil || !bytes.Equal(prefix, []byte(MediaIDPrefix)) {
+		return fmt.Errorf("%w: prefix not found", ErrInvalidMediaID)
+	}
+	versionAndClass := make([]byte, 2)
+	_, err = io.ReadFull(from, versionAndClass)
+	if err != nil {
+		return fmt.Errorf("%w: version and class not found", ErrInvalidMediaID)
+	} else if versionAndClass[0] != MediaIDVersion {
+		return fmt.Errorf("%w: unknown version %d", ErrUnsupportedMediaID, versionAndClass[0])
+	}
+	switch MediaIDClass(versionAndClass[1]) {
+	case MediaIDClassAttachment:
+		mid.Data = &AttachmentMediaData{}
+	case MediaIDClassEmoji:
+		mid.Data = &EmojiMediaData{}
+	case MediaIDClassSticker:
+		mid.Data = &StickerMediaData{}
+	case MediaIDClassUserAvatar:
+		mid.Data = &UserAvatarMediaData{}
+	case MediaIDClassGuildMemberAvatar:
+		mid.Data = &GuildMemberAvatarMediaData{}
+	default:
+		return fmt.Errorf("%w: unrecognized type class %d", ErrUnsupportedMediaID, versionAndClass[1])
+	}
+	err = mid.Data.Read(from)
+	if err != nil {
+		return fmt.Errorf("failed to parse media ID data: %w", err)
+	}
+	return nil
+}
+
+type AttachmentMediaData struct {
+	ChannelID    uint64
+	MessageID    uint64
+	AttachmentID uint64
+}
+
+func (amd *AttachmentMediaData) Write(to io.Writer) {
+	_ = binary.Write(to, binary.BigEndian, amd)
+}
+
+func (amd *AttachmentMediaData) Read(from io.Reader) (err error) {
+	return binary.Read(from, binary.BigEndian, amd)
+}
+
+func (amd *AttachmentMediaData) Size() int {
+	return binary.Size(amd)
+}
+
+func (amd *AttachmentMediaData) Wrap() *MediaID {
+	return &MediaID{
+		Version:   MediaIDVersion,
+		TypeClass: MediaIDClassAttachment,
+		Data:      amd,
+	}
+}
+
+func (amd *AttachmentMediaData) CacheKey() AttachmentCacheKey {
+	return AttachmentCacheKey{
+		ChannelID:    amd.ChannelID,
+		AttachmentID: amd.AttachmentID,
+	}
+}
+
+type StickerMediaData struct {
+	StickerID uint64
+	Format    uint8
+}
+
+func (smd *StickerMediaData) Write(to io.Writer) {
+	_ = binary.Write(to, binary.BigEndian, smd)
+}
+
+func (smd *StickerMediaData) Read(from io.Reader) error {
+	return binary.Read(from, binary.BigEndian, smd)
+}
+
+func (smd *StickerMediaData) Size() int {
+	return binary.Size(smd)
+}
+
+func (smd *StickerMediaData) Wrap() *MediaID {
+	return &MediaID{
+		Version:   MediaIDVersion,
+		TypeClass: MediaIDClassSticker,
+		Data:      smd,
+	}
+}
+
+type EmojiMediaDataInner struct {
+	EmojiID  uint64
+	Animated bool
+}
+
+type EmojiMediaData struct {
+	EmojiMediaDataInner
+	Name string
+}
+
+func (emd *EmojiMediaData) Write(to io.Writer) {
+	_ = binary.Write(to, binary.BigEndian, &emd.EmojiMediaDataInner)
+	_, _ = to.Write([]byte(emd.Name))
+}
+
+func (emd *EmojiMediaData) Read(from io.Reader) (err error) {
+	err = binary.Read(from, binary.BigEndian, &emd.EmojiMediaDataInner)
+	if err != nil {
+		return
+	}
+	name, err := io.ReadAll(from)
+	if err != nil {
+		return
+	}
+	emd.Name = string(name)
+	return
+}
+
+func (emd *EmojiMediaData) Size() int {
+	return binary.Size(&emd.EmojiMediaDataInner) + len(emd.Name)
+}
+
+func (emd *EmojiMediaData) Wrap() *MediaID {
+	return &MediaID{
+		Version:   MediaIDVersion,
+		TypeClass: MediaIDClassEmoji,
+		Data:      emd,
+	}
+}
+
+type UserAvatarMediaData struct {
+	UserID   uint64
+	Animated bool
+	AvatarID [16]byte
+}
+
+func (uamd *UserAvatarMediaData) Write(to io.Writer) {
+	_ = binary.Write(to, binary.BigEndian, uamd)
+}
+
+func (uamd *UserAvatarMediaData) Read(from io.Reader) error {
+	return binary.Read(from, binary.BigEndian, uamd)
+}
+
+func (uamd *UserAvatarMediaData) Size() int {
+	return binary.Size(uamd)
+}
+
+func (uamd *UserAvatarMediaData) Wrap() *MediaID {
+	return &MediaID{
+		Version:   MediaIDVersion,
+		TypeClass: MediaIDClassUserAvatar,
+		Data:      uamd,
+	}
+}
+
+type GuildMemberAvatarMediaData struct {
+	GuildID  uint64
+	UserID   uint64
+	Animated bool
+	AvatarID [16]byte
+}
+
+func (guamd *GuildMemberAvatarMediaData) Write(to io.Writer) {
+	_ = binary.Write(to, binary.BigEndian, guamd)
+}
+
+func (guamd *GuildMemberAvatarMediaData) Read(from io.Reader) error {
+	return binary.Read(from, binary.BigEndian, guamd)
+}
+
+func (guamd *GuildMemberAvatarMediaData) Size() int {
+	return binary.Size(guamd)
+}
+
+func (guamd *GuildMemberAvatarMediaData) Wrap() *MediaID {
+	return &MediaID{
+		Version:   MediaIDVersion,
+		TypeClass: MediaIDClassGuildMemberAvatar,
+		Data:      guamd,
+	}
+}

example-config.yaml

@@ -168,20 +168,23 @@ bridge:
     # This can be `never` to never cache, `unencrypted` to only cache unencrypted mxc uris, or `always` to cache everything.
     # If you have a media repo that generates non-unique mxc uris, you should set this to never.
     cache_media: unencrypted
-    # Patterns for converting Discord media to custom mxc:// URIs instead of reuploading.
+    # Settings for converting Discord media to custom mxc:// URIs instead of reuploading.
-    # Each of the patterns can be set to null to disable custom URIs for that type of media.
     # More details can be found at https://docs.mau.fi/bridges/go/discord/direct-media.html
-    media_patterns:
+    direct_media:
         # Should custom mxc:// URIs be used instead of reuploading media?
         enabled: false
-        # Pattern for normal message attachments.
+        # The server name to use for the custom mxc:// URIs.
-        attachments: mxc://discord-media.mau.dev/attachments|{{.ChannelID}}|{{.AttachmentID}}|{{.FileName}}
+        # This server name will effectively be a real Matrix server, it just won't implement anything other than media.
-        # Pattern for custom emojis.
+        # You must either set up .well-known delegation from this domain to the bridge, or proxy the domain directly to the bridge.
-        emojis: mxc://discord-media.mau.dev/emojis|{{.ID}}.{{.Ext}}
+        server_name: discord-media.example.com
-        # Pattern for stickers. Note that animated lottie stickers will not be converted if this is enabled.
+        # Optionally a custom .well-known response. This defaults to `server_name:443`
-        stickers: mxc://discord-media.mau.dev/stickers|{{.ID}}.{{.Ext}}
+        well_known_response:
-        # Pattern for static user avatars.
+        # The bridge supports MSC3860 media download redirects and will use them if the requester supports it.
-        avatars: mxc://discord-media.mau.dev/avatars|{{.UserID}}|{{.AvatarID}}.{{.Ext}}
+        # Optionally, you can force redirects and not allow proxying at all by setting this to false.
+        allow_proxy: true
+        # Matrix server signing key to make the federation tester pass, same format as synapse's .signing.key file.
+        # This key is also used to sign the mxc:// URIs to ensure only the bridge can generate them.
+        server_key: generate
     # Settings for converting animated stickers.
     animated_sticker:
         # Format to which animated stickers should be converted.

go.mod

@@ -18,7 +18,7 @@ require (
 	golang.org/x/exp v0.0.0-20231219180239-dc181d75b848
 	golang.org/x/sync v0.5.0
 	maunium.net/go/maulogger/v2 v2.4.1
-	maunium.net/go/mautrix v0.16.2
+	maunium.net/go/mautrix v0.16.3-0.20240218195727-4ceb1123b660
 )
 
 require (

go.sum

@@ -71,5 +71,5 @@ maunium.net/go/mauflag v1.0.0 h1:YiaRc0tEI3toYtJMRIfjP+jklH45uDHtT80nUamyD4M=
 maunium.net/go/mauflag v1.0.0/go.mod h1:nLivPOpTpHnpzEh8jEdSL9UqO9+/KBJFmNRlwKfkPeA=
 maunium.net/go/maulogger/v2 v2.4.1 h1:N7zSdd0mZkB2m2JtFUsiGTQQAdP0YeFWT7YMc80yAL8=
 maunium.net/go/maulogger/v2 v2.4.1/go.mod h1:omPuYwYBILeVQobz8uO3XC8DIRuEb5rXYlQSuqrbCho=
-maunium.net/go/mautrix v0.16.2 h1:a6GUJXNWsTEOO8VE4dROBfCIfPp50mqaqzv7KPzChvg=
+maunium.net/go/mautrix v0.16.3-0.20240218195727-4ceb1123b660 h1:ZPg1i0wsyEs5ee7z6Gn4mSRsq9BtDV//rfYTGs82l8c=
-maunium.net/go/mautrix v0.16.2/go.mod h1:YL4l4rZB46/vj/ifRMEjcibbvHjgxHftOF1SgmruLu4=
+maunium.net/go/mautrix v0.16.3-0.20240218195727-4ceb1123b660/go.mod h1:YL4l4rZB46/vj/ifRMEjcibbvHjgxHftOF1SgmruLu4=

main.go

@@ -48,6 +48,7 @@ type DiscordBridge struct {
 	Config *config.Config
 	DB     *database.Database
 
+	DMA          *DirectMediaAPI
 	provisioning *ProvisioningAPI
 
 	usersByMXID map[id.UserID]*User
@@ -104,6 +105,7 @@ func (br *DiscordBridge) Start() {
 	if br.Config.Bridge.Provisioning.SharedSecret != "disable" {
 		br.provisioning = newProvisioningAPI(br)
 	}
+	br.DMA = newDirectMediaAPI(br)
 	br.WaitWebsocketConnected()
 	go br.startUsers()
 }

portal.go

@@ -1832,13 +1832,15 @@ func (portal *Portal) handleMatrixReaction(sender *User, evt *event.Event) {
 	emojiID := reaction.RelatesTo.Key
 	if strings.HasPrefix(emojiID, "mxc://") {
 		uri, _ := id.ParseContentURI(emojiID)
-		emojiFile := portal.bridge.DB.File.GetEmojiByMXC(uri)
+		emojiInfo := portal.bridge.DMA.GetEmojiInfo(uri)
-		if emojiFile == nil || emojiFile.ID == "" || emojiFile.EmojiName == "" {
+		if emojiInfo != nil {
+			emojiID = fmt.Sprintf("%s:%d", emojiInfo.Name, emojiInfo.EmojiID)
+		} else if emojiFile := portal.bridge.DB.File.GetEmojiByMXC(uri); emojiFile != nil && emojiFile.ID != "" && emojiFile.EmojiName != "" {
+			emojiID = fmt.Sprintf("%s:%s", emojiFile.EmojiName, emojiFile.ID)
+		} else {
 			go portal.sendMessageMetrics(evt, fmt.Errorf("%w %s", errUnknownEmoji, emojiID), "Ignoring")
 			return
 		}
-
-		emojiID = fmt.Sprintf("%s:%s", emojiFile.EmojiName, emojiFile.ID)
 	} else {
 		emojiID = variationselector.FullyQualify(emojiID)
 	}

portal_convert.go

@@ -27,12 +27,11 @@ import (
 	"github.com/bwmarrin/discordgo"
 	"github.com/rs/zerolog"
 	"golang.org/x/exp/slices"
-	"maunium.net/go/mautrix/id"
-
 	"maunium.net/go/mautrix"
 	"maunium.net/go/mautrix/appservice"
 	"maunium.net/go/mautrix/event"
 	"maunium.net/go/mautrix/format"
+	"maunium.net/go/mautrix/id"
 )
 
 type ConvertedMessage struct {
@@ -103,20 +102,16 @@ func (portal *Portal) cleanupConvertedStickerInfo(content *event.MessageEventCon
 }
 
 func (portal *Portal) convertDiscordSticker(ctx context.Context, intent *appservice.IntentAPI, sticker *discordgo.Sticker) *ConvertedMessage {
-	var mime, ext string
+	var mime string
 	switch sticker.FormatType {
 	case discordgo.StickerFormatTypePNG:
 		mime = "image/png"
-		ext = "png"
 	case discordgo.StickerFormatTypeAPNG:
 		mime = "image/apng"
-		ext = "png"
 	case discordgo.StickerFormatTypeLottie:
 		mime = "application/json"
-		ext = "json"
 	case discordgo.StickerFormatTypeGIF:
 		mime = "image/gif"
-		ext = "gif"
 	default:
 		zerolog.Ctx(ctx).Warn().
 			Int("sticker_format", int(sticker.FormatType)).
@@ -130,8 +125,9 @@ func (portal *Portal) convertDiscordSticker(ctx context.Context, intent *appserv
 		},
 	}
 
-	mxc := portal.bridge.Config.Bridge.MediaPatterns.Sticker(sticker.ID, ext)
+	mxc := portal.bridge.DMA.StickerMXC(sticker.ID, sticker.FormatType)
-	if mxc.IsEmpty() {
+	// TODO add config option to use direct media even for lottie stickers
+	if mxc.IsEmpty() && mime != "application/json" {
 		content = portal.convertDiscordFile(ctx, "sticker", intent, sticker.ID, sticker.URL(), content)
 	} else {
 		content.URL = mxc.CUString()
@@ -144,7 +140,7 @@ func (portal *Portal) convertDiscordSticker(ctx context.Context, intent *appserv
 	}
 }
 
-func (portal *Portal) convertDiscordAttachment(ctx context.Context, intent *appservice.IntentAPI, att *discordgo.MessageAttachment) *ConvertedMessage {
+func (portal *Portal) convertDiscordAttachment(ctx context.Context, intent *appservice.IntentAPI, messageID string, att *discordgo.MessageAttachment) *ConvertedMessage {
 	content := &event.MessageEventContent{
 		Body: att.Filename,
 		Info: &event.FileInfo{
@@ -182,7 +178,7 @@ func (portal *Portal) convertDiscordAttachment(ctx context.Context, intent *apps
 	default:
 		content.MsgType = event.MsgFile
 	}
-	mxc := portal.bridge.Config.Bridge.MediaPatterns.Attachment(portal.Key.ChannelID, att.ID, att.Filename)
+	mxc := portal.bridge.DMA.AttachmentMXC(portal.Key.ChannelID, messageID, att)
 	if mxc.IsEmpty() {
 		content = portal.convertDiscordFile(ctx, "attachment", intent, att.ID, att.URL, content)
 	} else {
@@ -287,7 +283,7 @@ func (portal *Portal) convertDiscordMessage(ctx context.Context, puppet *Puppet,
 		}
 		handledIDs[att.ID] = struct{}{}
 		log := log.With().Str("attachment_id", att.ID).Logger()
-		if part := portal.convertDiscordAttachment(log.WithContext(ctx), intent, att); part != nil {
+		if part := portal.convertDiscordAttachment(log.WithContext(ctx), intent, msg.ID, att); part != nil {
 			parts = append(parts, part)
 		}
 	}

puppet.go

@@ -217,27 +217,23 @@ func (puppet *Puppet) UpdateName(info *discordgo.User) bool {
 }
 
 func (br *DiscordBridge) reuploadUserAvatar(intent *appservice.IntentAPI, guildID, userID, avatarID string) (id.ContentURI, string, error) {
-	var downloadURL, ext string
+	var downloadURL string
 	if guildID == "" {
-		downloadURL = discordgo.EndpointUserAvatar(userID, avatarID)
-		ext = "png"
 		if strings.HasPrefix(avatarID, "a_") {
 			downloadURL = discordgo.EndpointUserAvatarAnimated(userID, avatarID)
-			ext = "gif"
+		} else {
+			downloadURL = discordgo.EndpointUserAvatar(userID, avatarID)
 		}
 	} else {
-		downloadURL = discordgo.EndpointGuildMemberAvatar(guildID, userID, avatarID)
-		ext = "png"
 		if strings.HasPrefix(avatarID, "a_") {
 			downloadURL = discordgo.EndpointGuildMemberAvatarAnimated(guildID, userID, avatarID)
-			ext = "gif"
+		} else {
+			downloadURL = discordgo.EndpointGuildMemberAvatar(guildID, userID, avatarID)
 		}
 	}
-	if guildID == "" {
+	url := br.DMA.AvatarMXC(guildID, userID, avatarID)
-		url := br.Config.Bridge.MediaPatterns.Avatar(userID, avatarID, ext)
+	if !url.IsEmpty() {
-		if !url.IsEmpty() {
+		return url, downloadURL, nil
-			return url, downloadURL, nil
-		}
 	}
 	copied, err := br.copyAttachmentToMatrix(intent, downloadURL, false, AttachmentMeta{
 		AttachmentID: fmt.Sprintf("avatar/%s/%s/%s", guildID, userID, avatarID),

user.go

@@ -195,6 +195,12 @@ func (br *DiscordBridge) GetCachedUserByID(id string) *User {
 	return br.usersByID[id]
 }
 
+func (br *DiscordBridge) GetCachedUserByMXID(userID id.UserID) *User {
+	br.usersLock.Lock()
+	defer br.usersLock.Unlock()
+	return br.usersByMXID[userID]
+}
+
 func (br *DiscordBridge) NewUser(dbUser *database.User) *User {
 	user := &User{
 		User:   dbUser,