msgconv: clean up reuploading attachments to Matrix

pkg/attachment/attachment.go

@@ -1,39 +0,0 @@
-// mautrix-discord - A Matrix-Discord puppeting bridge.
-// Copyright (C) 2026 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 attachment
-
-import (
-	"maunium.net/go/mautrix/event"
-	"maunium.net/go/mautrix/id"
-)
-
-// TODO(skip): These types are only in a leaf package to avoid import cycles.
-// Perhaps figure out a better way to structure this so that this package is unnecessary.
-
-type AttachmentReupload struct {
-	DownloadingURL string
-	FileName       string
-	MimeType       string
-}
-
-type ReuploadedAttachment struct {
-	AttachmentReupload
-	DownloadedSize int
-	MXC            id.ContentURIString
-	// This can be nil if the room isn't encrypted.
-	EncryptedFile *event.EncryptedFileInfo
-}

pkg/connector/attachments.go

@@ -1,104 +0,0 @@
-// mautrix-discord - A Matrix-Discord puppeting bridge.
-// Copyright (C) 2026 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 connector
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"io"
-	"net/http"
-	"net/url"
-	"path"
-	"strconv"
-
-	"github.com/bwmarrin/discordgo"
-	"maunium.net/go/mautrix/bridgev2"
-
-	"go.mau.fi/mautrix-discord/pkg/attachment"
-)
-
-func downloadDiscordAttachment(cli *http.Client, url string, maxSize int64) ([]byte, error) {
-	req, err := http.NewRequest(http.MethodGet, url, nil)
-	if err != nil {
-		return nil, err
-	}
-	for key, value := range discordgo.DroidDownloadHeaders {
-		req.Header.Set(key, value)
-	}
-
-	resp, err := cli.Do(req)
-	if err != nil {
-		return nil, err
-	}
-	defer resp.Body.Close()
-	if resp.StatusCode > 300 {
-		data, _ := io.ReadAll(resp.Body)
-		return nil, fmt.Errorf("unexpected status %d downloading %s: %s", resp.StatusCode, url, data)
-	}
-	if resp.Header.Get("Content-Length") != "" {
-		length, err := strconv.ParseInt(resp.Header.Get("Content-Length"), 10, 64)
-		if err != nil {
-			return nil, fmt.Errorf("failed to parse content length: %w", err)
-		} else if length > maxSize {
-			return nil, fmt.Errorf("attachment too large (%d > %d)", length, maxSize)
-		}
-		return io.ReadAll(resp.Body)
-	} else {
-		var mbe *http.MaxBytesError
-		data, err := io.ReadAll(http.MaxBytesReader(nil, resp.Body, maxSize))
-		if err != nil && errors.As(err, &mbe) {
-			return nil, fmt.Errorf("attachment too large (over %d)", maxSize)
-		}
-		return data, err
-	}
-}
-
-func (d *DiscordConnector) ReuploadMedia(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, upload attachment.AttachmentReupload) (*attachment.ReuploadedAttachment, error) {
-	// TODO(skip): Do we need to check if we've already downloaded this media before?
-	// TODO(skip): Read a maximum size from the config.
-	data, err := downloadDiscordAttachment(http.DefaultClient, upload.DownloadingURL, 1_024*1_024*50)
-	if err != nil {
-		return nil, fmt.Errorf("couldn't download attachment for reupload: %w", err)
-	}
-
-	if upload.FileName == "" {
-		url, err := url.Parse(upload.DownloadingURL)
-		if err != nil {
-			return nil, fmt.Errorf("couldn't parse URL to download for media reupload: %w", err)
-		}
-		fileName := path.Base(url.Path)
-		upload.FileName = fileName
-	}
-
-	if upload.MimeType == "" {
-		mime := http.DetectContentType(data)
-		upload.MimeType = mime
-	}
-
-	mxc, file, err := intent.UploadMedia(ctx, portal.MXID, data, upload.FileName, upload.MimeType)
-	if err != nil {
-		return nil, err
-	}
-
-	return &attachment.ReuploadedAttachment{
-		AttachmentReupload: upload,
-		DownloadedSize:     len(data),
-		MXC:                mxc,
-		EncryptedFile:      file,
-	}, nil
-}

pkg/connector/backfill.go

@@ -100,7 +100,7 @@ func (dc *DiscordClient) FetchMessages(ctx context.Context, fetchParams bridgev2
 
 		converted = append(converted, &bridgev2.BackfillMessage{
 			ID:               networkid.MessageID(msg.ID),
-			ConvertedMessage: dc.connector.MsgConv.ToMatrix(ctx, fetchParams.Portal, intent, dc.UserLogin, msg),
+			ConvertedMessage: dc.connector.MsgConv.ToMatrix(ctx, fetchParams.Portal, intent, dc.UserLogin, dc.Session, msg),
 			Sender:           sender,
 			Timestamp:        ts,
 			StreamOrder:      streamOrder,

pkg/connector/connector.go

@@ -30,14 +30,21 @@ type DiscordConnector struct {
 	MsgConv *msgconv.MessageConverter
 }
 
-var _ bridgev2.NetworkConnector = (*DiscordConnector)(nil)
+var (
+	_ bridgev2.NetworkConnector      = (*DiscordConnector)(nil)
+	_ bridgev2.MaxFileSizeingNetwork = (*DiscordConnector)(nil)
+)
 
 func (d *DiscordConnector) Init(bridge *bridgev2.Bridge) {
 	d.Bridge = bridge
-	d.MsgConv = msgconv.NewMessageConverter(bridge, d.ReuploadMedia)
+	d.MsgConv = msgconv.NewMessageConverter(bridge)
 	d.setUpProvisioningAPIs()
 }
 
+func (d *DiscordConnector) SetMaxFileSize(maxSize int64) {
+	d.MsgConv.MaxFileSize = maxSize
+}
+
 func (d *DiscordConnector) Start(ctx context.Context) error {
 	return nil
 }

pkg/connector/handlediscord.go

@@ -63,7 +63,7 @@ var (
 )
 
 func (m *DiscordMessage) ConvertMessage(ctx context.Context, portal *bridgev2.Portal, intent bridgev2.MatrixAPI) (*bridgev2.ConvertedMessage, error) {
-	return m.Client.connector.MsgConv.ToMatrix(ctx, portal, intent, m.Client.UserLogin, m.Data), nil
+	return m.Client.connector.MsgConv.ToMatrix(ctx, portal, intent, m.Client.UserLogin, m.Client.Session, m.Data), nil
 }
 
 func (m *DiscordMessage) GetID() networkid.MessageID {

pkg/msgconv/attachments.go

@@ -0,0 +1,147 @@
+// mautrix-discord - A Matrix-Discord puppeting bridge.
+// Copyright (C) 2026 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 msgconv
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"path"
+
+	"github.com/bwmarrin/discordgo"
+	"github.com/rs/zerolog"
+	"maunium.net/go/mautrix/bridgev2"
+	"maunium.net/go/mautrix/event"
+	"maunium.net/go/mautrix/id"
+)
+
+type ReuploadedAttachment struct {
+	MXC      id.ContentURIString
+	File     *event.EncryptedFileInfo
+	Size     int
+	FileName string
+	MimeType string
+}
+
+func (d *MessageConverter) ReuploadUnknownMedia(
+	ctx context.Context,
+	url string,
+	allowEncryption bool,
+) (*ReuploadedAttachment, error) {
+	return d.ReuploadMedia(ctx, url, "", "", -1, allowEncryption)
+}
+
+func mib(size int64) float64 {
+	return float64(size) / 1024 / 1024
+}
+
+func (d *MessageConverter) ReuploadMedia(
+	ctx context.Context,
+	downloadURL string,
+	mimeType string,
+	fileName string,
+	estimatedSize int,
+	allowEncryption bool,
+) (*ReuploadedAttachment, error) {
+	if fileName == "" {
+		parsedURL, err := url.Parse(downloadURL)
+		if err != nil {
+			return nil, fmt.Errorf("couldn't parse URL to detect file name: %w", err)
+		}
+		fileName = path.Base(parsedURL.Path)
+	}
+
+	sess := ctx.Value(contextKeyDiscordClient).(*discordgo.Session)
+	httpClient := sess.Client
+	intent := ctx.Value(contextKeyIntent).(bridgev2.MatrixAPI)
+	var roomID id.RoomID
+	if allowEncryption {
+		roomID = ctx.Value(contextKeyPortal).(*bridgev2.Portal).MXID
+	}
+
+	req, err := http.NewRequest(http.MethodGet, downloadURL, nil)
+	if err != nil {
+		return nil, err
+	}
+	if sess.IsUser {
+		for key, value := range discordgo.DroidDownloadHeaders {
+			req.Header.Set(key, value)
+		}
+	}
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode > 300 {
+		errBody, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
+		logEvt := zerolog.Ctx(ctx).Error().
+			Str("media_url", downloadURL).
+			Int("status_code", resp.StatusCode)
+		if json.Valid(errBody) {
+			logEvt.RawJSON("error_json", errBody)
+		} else {
+			logEvt.Bytes("error_body", errBody)
+		}
+		logEvt.Msg("Media download failed")
+		return nil, fmt.Errorf("%w: unexpected status code %d", bridgev2.ErrMediaDownloadFailed, resp.StatusCode)
+	} else if resp.ContentLength > d.MaxFileSize {
+		return nil, fmt.Errorf("%w (%.2f MiB > %.2f MiB)", bridgev2.ErrMediaTooLarge, mib(resp.ContentLength), mib(d.MaxFileSize))
+	}
+
+	requireFile := mimeType == ""
+	var size int64
+	mxc, file, err := intent.UploadMediaStream(ctx, roomID, int64(estimatedSize), requireFile, func(file io.Writer) (*bridgev2.FileStreamResult, error) {
+		var mbe *http.MaxBytesError
+		size, err = io.Copy(file, http.MaxBytesReader(nil, resp.Body, d.MaxFileSize))
+		if err != nil {
+			if errors.As(err, &mbe) {
+				return nil, fmt.Errorf("%w (over %.2f MiB)", bridgev2.ErrMediaTooLarge, mib(d.MaxFileSize))
+			}
+			return nil, err
+		}
+		if mimeType == "" {
+			mimeBuf := make([]byte, 512)
+			n, err := file.(*os.File).ReadAt(mimeBuf, 0)
+			if err != nil {
+				return nil, fmt.Errorf("couldn't read file for mime detection: %w", err)
+			}
+			mimeType = http.DetectContentType(mimeBuf[:n])
+		}
+		return &bridgev2.FileStreamResult{
+			FileName: fileName,
+			MimeType: mimeType,
+		}, nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return &ReuploadedAttachment{
+		Size:     int(size),
+		MXC:      mxc,
+		File:     file,
+		FileName: fileName,
+		MimeType: mimeType,
+	}, nil
+}

pkg/msgconv/from-discord.go

@@ -26,22 +26,36 @@ import (
 
 	"github.com/bwmarrin/discordgo"
 	"github.com/rs/zerolog"
+	"go.mau.fi/util/exmaps"
 	"maunium.net/go/mautrix/bridgev2"
 	"maunium.net/go/mautrix/bridgev2/networkid"
 	"maunium.net/go/mautrix/event"
 	"maunium.net/go/mautrix/format"
 
-	"go.mau.fi/mautrix-discord/pkg/attachment"
 	"go.mau.fi/mautrix-discord/pkg/discordid"
 )
 
+type contextKey int
+
+const (
+	contextKeyPortal contextKey = iota
+	contextKeyIntent
+	contextKeyUserLogin
+	contextKeyDiscordClient
+)
+
 func (mc *MessageConverter) ToMatrix(
 	ctx context.Context,
 	portal *bridgev2.Portal,
 	intent bridgev2.MatrixAPI,
 	source *bridgev2.UserLogin,
+	session *discordgo.Session,
 	msg *discordgo.Message,
 ) *bridgev2.ConvertedMessage {
+	ctx = context.WithValue(ctx, contextKeyUserLogin, source)
+	ctx = context.WithValue(ctx, contextKeyIntent, intent)
+	ctx = context.WithValue(ctx, contextKeyPortal, portal)
+	ctx = context.WithValue(ctx, contextKeyDiscordClient, session)
 	predictedLength := len(msg.Attachments) + len(msg.StickerItems)
 	if msg.Content != "" {
 		predictedLength++
@@ -56,28 +70,26 @@ func (mc *MessageConverter) ToMatrix(
 		Str("message_id", msg.ID).
 		Logger().WithContext(ctx)
 	log := zerolog.Ctx(ctx)
-	handledIDs := make(map[string]struct{})
+	handledIDs := make(exmaps.Set[string])
 
 	for _, att := range msg.Attachments {
-		if _, handled := handledIDs[att.ID]; handled {
+		if !handledIDs.Add(att.ID) {
 			continue
 		}
-		handledIDs[att.ID] = struct{}{}
 
 		log := log.With().Str("attachment_id", att.ID).Logger()
-		if part := mc.renderDiscordAttachment(log.WithContext(ctx), intent, portal, att); part != nil {
+		if part := mc.renderDiscordAttachment(log.WithContext(ctx), att); part != nil {
 			parts = append(parts, part)
 		}
 	}
 
 	for _, sticker := range msg.StickerItems {
-		if _, handled := handledIDs[sticker.ID]; handled {
+		if !handledIDs.Add(sticker.ID) {
 			continue
 		}
-		handledIDs[sticker.ID] = struct{}{}
 
 		log := log.With().Str("sticker_id", sticker.ID).Logger()
-		if part := mc.renderDiscordSticker(log.WithContext(ctx), intent, sticker); part != nil {
+		if part := mc.renderDiscordSticker(log.WithContext(ctx), sticker); part != nil {
 			parts = append(parts, part)
 		}
 	}
@@ -88,17 +100,16 @@ func (mc *MessageConverter) ToMatrix(
 			continue
 		}
 		// Discord deduplicates embeds by URL. It makes things easier for us too.
-		if _, handled := handledIDs[embed.URL]; handled {
+		if !handledIDs.Add(embed.URL) {
 			continue
 		}
-		handledIDs[embed.URL] = struct{}{}
 
 		log := log.With().
 			Str("computed_embed_type", "video").
 			Str("embed_type", string(embed.Type)).
 			Int("embed_index", i).
 			Logger()
-		part := mc.renderDiscordVideoEmbed(log.WithContext(ctx), intent, portal, embed)
+		part := mc.renderDiscordVideoEmbed(log.WithContext(ctx), embed)
 		if part != nil {
 			parts = append(parts, part)
 		}
@@ -235,7 +246,7 @@ func (mc *MessageConverter) renderDiscordTextMessage(ctx context.Context, intent
 		len(msg.MessageSnapshots) > 0 &&
 		msg.MessageSnapshots[0].Message != nil {
 		// Bridge forwarded messages.
-		htmlParts = append(htmlParts, mc.forwardedMessageHtmlPart(ctx, portal, source, msg))
+		htmlParts = append(htmlParts, mc.forwardedMessageHTMLPart(ctx, portal, source, msg))
 	}
 
 	previews := make([]*event.BeeperLinkPreview, 0)
@@ -251,10 +262,10 @@ func (mc *MessageConverter) renderDiscordTextMessage(ctx context.Context, intent
 		switch getEmbedType(msg, embed) {
 		case EmbedRich:
 			log := with.Str("computed_embed_type", "rich").Logger()
-			htmlParts = append(htmlParts, mc.renderDiscordRichEmbed(log.WithContext(ctx), intent, portal, embed))
+			htmlParts = append(htmlParts, mc.renderDiscordRichEmbed(log.WithContext(ctx), embed))
 		case EmbedLinkPreview:
 			log := with.Str("computed_embed_type", "link preview").Logger()
-			previews = append(previews, mc.renderDiscordLinkEmbed(log.WithContext(ctx), intent, portal, embed))
+			previews = append(previews, mc.renderDiscordLinkEmbed(log.WithContext(ctx), embed))
 		case EmbedVideo:
 			// Video embeds are handled as separate messages via renderDiscordVideoEmbed.
 		default:
@@ -284,7 +295,7 @@ func (mc *MessageConverter) renderDiscordTextMessage(ctx context.Context, intent
 	return &bridgev2.ConvertedMessagePart{Type: event.EventMessage, Content: &content, Extra: extraContent}
 }
 
-func (mc *MessageConverter) forwardedMessageHtmlPart(ctx context.Context, portal *bridgev2.Portal, source *bridgev2.UserLogin, msg *discordgo.Message) string {
+func (mc *MessageConverter) forwardedMessageHTMLPart(ctx context.Context, portal *bridgev2.Portal, source *bridgev2.UserLogin, msg *discordgo.Message) string {
 	log := zerolog.Ctx(ctx)
 
 	forwardedHTML := mc.renderDiscordMarkdownOnlyHTMLNoUnwrap(portal, msg.MessageSnapshots[0].Message.Content, true)
@@ -327,7 +338,7 @@ func mediaFailedMessage(err error) *event.MessageEventContent {
 	}
 }
 
-func (mc *MessageConverter) renderDiscordVideoEmbed(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, embed *discordgo.MessageEmbed) *bridgev2.ConvertedMessagePart {
+func (mc *MessageConverter) renderDiscordVideoEmbed(ctx context.Context, embed *discordgo.MessageEmbed) *bridgev2.ConvertedMessagePart {
 	var proxyURL string
 	if embed.Video != nil {
 		proxyURL = embed.Video.ProxyURL
@@ -344,10 +355,7 @@ func (mc *MessageConverter) renderDiscordVideoEmbed(ctx context.Context, intent
 		}
 	}
 
-	upload := attachment.AttachmentReupload{
+	reupload, err := mc.ReuploadUnknownMedia(ctx, proxyURL, true)
-		DownloadingURL: proxyURL,
-	}
-	reupload, err := mc.ReuploadMedia(ctx, intent, portal, upload)
 	if err != nil {
 		zerolog.Ctx(ctx).Err(err).Msg("Failed to copy video embed to Matrix")
 		return &bridgev2.ConvertedMessagePart{
@@ -358,16 +366,13 @@ func (mc *MessageConverter) renderDiscordVideoEmbed(ctx context.Context, intent
 
 	content := &event.MessageEventContent{
 		Body: embed.URL,
+		URL:  reupload.MXC,
+		File: reupload.File,
 		Info: &event.FileInfo{
 			MimeType: reupload.MimeType,
-			Size:     reupload.DownloadedSize,
+			Size:     reupload.Size,
 		},
 	}
-	if reupload.EncryptedFile != nil {
-		content.File = reupload.EncryptedFile
-	} else {
-		content.URL = reupload.MXC
-	}
 
 	if embed.Video != nil {
 		content.MsgType = event.MsgVideo
@@ -398,7 +403,7 @@ func (mc *MessageConverter) renderDiscordVideoEmbed(ctx context.Context, intent
 	}
 }
 
-func (mc *MessageConverter) renderDiscordSticker(context context.Context, intent bridgev2.MatrixAPI, sticker *discordgo.StickerItem) *bridgev2.ConvertedMessagePart {
+func (mc *MessageConverter) renderDiscordSticker(ctx context.Context, sticker *discordgo.StickerItem) *bridgev2.ConvertedMessagePart {
 	panic("unimplemented")
 }
 
@@ -423,7 +428,7 @@ const (
 	embedFooterDateSeparator = ` • `
 )
 
-func (mc *MessageConverter) renderDiscordRichEmbed(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, embed *discordgo.MessageEmbed) string {
+func (mc *MessageConverter) renderDiscordRichEmbed(ctx context.Context, embed *discordgo.MessageEmbed) string {
 	log := zerolog.Ctx(ctx)
 	var htmlParts []string
 	if embed.Author != nil {
@@ -434,9 +439,7 @@ func (mc *MessageConverter) renderDiscordRichEmbed(ctx context.Context, intent b
 		}
 		authorHTML = fmt.Sprintf(embedHTMLAuthorPlain, authorNameHTML)
 		if embed.Author.ProxyIconURL != "" {
-			reupload, err := mc.ReuploadMedia(ctx, intent, portal, attachment.AttachmentReupload{
+			reupload, err := mc.ReuploadUnknownMedia(ctx, embed.Author.ProxyIconURL, false)
-				DownloadingURL: embed.Author.ProxyIconURL,
-			})
 
 			if err != nil {
 				log.Warn().Err(err).Msg("Failed to reupload author icon in embed")
@@ -447,6 +450,7 @@ func (mc *MessageConverter) renderDiscordRichEmbed(ctx context.Context, intent b
 		htmlParts = append(htmlParts, authorHTML)
 	}
 
+	portal := ctx.Value(contextKeyPortal).(*bridgev2.Portal)
 	if embed.Title != "" {
 		var titleHTML string
 		baseTitleHTML := mc.renderDiscordMarkdownOnlyHTML(portal, embed.Title, false)
@@ -492,9 +496,7 @@ func (mc *MessageConverter) renderDiscordRichEmbed(ctx context.Context, intent b
 	}
 
 	if embed.Image != nil {
-		reupload, err := mc.ReuploadMedia(ctx, intent, portal, attachment.AttachmentReupload{
+		reupload, err := mc.ReuploadUnknownMedia(ctx, embed.Image.ProxyURL, false)
-			DownloadingURL: embed.Image.ProxyURL,
-		})
 		if err != nil {
 			log.Warn().Err(err).Msg("Failed to reupload image in embed")
 		} else {
@@ -522,9 +524,7 @@ func (mc *MessageConverter) renderDiscordRichEmbed(ctx context.Context, intent b
 		}
 		footerHTML = fmt.Sprintf(embedHTMLFooterPlain, html.EscapeString(embed.Footer.Text), datePart)
 		if embed.Footer.ProxyIconURL != "" {
-			reupload, err := mc.ReuploadMedia(ctx, intent, portal, attachment.AttachmentReupload{
+			reupload, err := mc.ReuploadUnknownMedia(ctx, embed.Footer.ProxyIconURL, false)
-				DownloadingURL: embed.Footer.ProxyIconURL,
-			})
 
 			if err != nil {
 				log.Warn().Err(err).Msg("Failed to reupload footer icon in embed")
@@ -550,10 +550,10 @@ func (mc *MessageConverter) renderDiscordRichEmbed(ctx context.Context, intent b
 	return compiledHTML
 }
 
-func (mc *MessageConverter) renderDiscordLinkEmbedImage(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, url string, width, height int, preview *event.BeeperLinkPreview) {
+func (mc *MessageConverter) renderDiscordLinkEmbedImage(
-	reupload, err := mc.ReuploadMedia(ctx, intent, portal, attachment.AttachmentReupload{
+	ctx context.Context, url string, width, height int, preview *event.BeeperLinkPreview,
-		DownloadingURL: url,
+) {
-	})
+	reupload, err := mc.ReuploadUnknownMedia(ctx, url, true)
 	if err != nil {
 		zerolog.Ctx(ctx).Warn().Err(err).Msg("Failed to reupload image in URL preview, ignoring")
 		return
@@ -563,39 +563,42 @@ func (mc *MessageConverter) renderDiscordLinkEmbedImage(ctx context.Context, int
 		preview.ImageWidth = event.IntOrString(width)
 		preview.ImageHeight = event.IntOrString(height)
 	}
-	preview.ImageSize = event.IntOrString(reupload.DownloadedSize)
+	preview.ImageSize = event.IntOrString(reupload.Size)
 	preview.ImageType = reupload.MimeType
-	if reupload.EncryptedFile != nil {
+	preview.ImageURL, preview.ImageEncryption = reupload.MXC, reupload.File
-		preview.ImageEncryption = &event.EncryptedFileInfo{
-			EncryptedFile: reupload.EncryptedFile.EncryptedFile,
-			URL:           reupload.MXC,
-		}
-	}
 }
 
-func (mc *MessageConverter) renderDiscordLinkEmbed(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, embed *discordgo.MessageEmbed) *event.BeeperLinkPreview {
+func (mc *MessageConverter) renderDiscordLinkEmbed(ctx context.Context, embed *discordgo.MessageEmbed) *event.BeeperLinkPreview {
 	var preview event.BeeperLinkPreview
 	preview.MatchedURL = embed.URL
 	preview.Title = embed.Title
 	preview.Description = embed.Description
 	if embed.Image != nil {
-		mc.renderDiscordLinkEmbedImage(ctx, intent, portal, embed.Image.ProxyURL, embed.Image.Width, embed.Image.Height, &preview)
+		mc.renderDiscordLinkEmbedImage(ctx, embed.Image.ProxyURL, embed.Image.Width, embed.Image.Height, &preview)
 	} else if embed.Thumbnail != nil {
-		mc.renderDiscordLinkEmbedImage(ctx, intent, portal, embed.Thumbnail.ProxyURL, embed.Thumbnail.Width, embed.Thumbnail.Height, &preview)
+		mc.renderDiscordLinkEmbedImage(ctx, embed.Thumbnail.ProxyURL, embed.Thumbnail.Width, embed.Thumbnail.Height, &preview)
 	}
 	return &preview
 }
 
-func (mc *MessageConverter) renderDiscordAttachment(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, att *discordgo.MessageAttachment) *bridgev2.ConvertedMessagePart {
+func (mc *MessageConverter) renderDiscordAttachment(ctx context.Context, att *discordgo.MessageAttachment) *bridgev2.ConvertedMessagePart {
+	// TODO(skip): Support direct media.
+	reupload, err := mc.ReuploadMedia(ctx, att.URL, att.ContentType, att.Filename, att.Size, true)
+	if err != nil {
+		zerolog.Ctx(ctx).Err(err).Msg("Failed to copy attachment to Matrix")
+		return &bridgev2.ConvertedMessagePart{
+			Type:    event.EventMessage,
+			Content: mediaFailedMessage(err),
+		}
+	}
+
 	content := &event.MessageEventContent{
-		Body: att.Filename,
+		Body: reupload.FileName,
 		Info: &event.FileInfo{
 			Width:    att.Width,
 			Height:   att.Height,
-			MimeType: att.ContentType,
+			MimeType: reupload.MimeType,
-
+			Size:     reupload.Size,
-			// This gets overwritten later after the file is uploaded to the homeserver
-			Size: att.Size,
 		},
 	}
 
@@ -607,10 +610,10 @@ func (mc *MessageConverter) renderDiscordAttachment(ctx context.Context, intent
 
 	if att.Description != "" {
 		content.Body = att.Description
-		content.FileName = att.Filename
+		content.FileName = reupload.FileName
 	}
 
-	switch strings.ToLower(strings.Split(att.ContentType, "/")[0]) {
+	switch strings.ToLower(strings.Split(content.Info.MimeType, "/")[0]) {
 	case "audio":
 		content.MsgType = event.MsgAudio
 		if att.Waveform != nil {
@@ -630,28 +633,12 @@ func (mc *MessageConverter) renderDiscordAttachment(ctx context.Context, intent
 		content.MsgType = event.MsgFile
 	}
 
-	// TODO(skip): Support direct media.
+	content.URL, content.File = reupload.MXC, reupload.File
-	reupload, err := mc.ReuploadMedia(ctx, intent, portal, attachment.AttachmentReupload{
+	content.Info.Size = reupload.Size
-		DownloadingURL: att.URL,
-	})
-	if err != nil {
-		zerolog.Ctx(ctx).Err(err).Msg("Failed to copy attachment to Matrix")
-		return &bridgev2.ConvertedMessagePart{
-			Type:    event.EventMessage,
-			Content: mediaFailedMessage(err),
-		}
-	}
-
-	content.Info.Size = reupload.DownloadedSize
 	if content.Info.Width == 0 && content.Info.Height == 0 {
 		content.Info.Width = att.Width
 		content.Info.Height = att.Height
 	}
-	if reupload.EncryptedFile != nil {
-		content.File = reupload.EncryptedFile
-	} else {
-		content.URL = reupload.MXC
-	}
 
 	return &bridgev2.ConvertedMessagePart{
 		Type:    event.EventMessage,

pkg/msgconv/from-matrix.go

@@ -99,6 +99,8 @@ func (mc *MessageConverter) ToDiscord(
 	session *discordgo.Session,
 	msg *bridgev2.MatrixMessage,
 ) (*discordgo.MessageSend, error) {
+	ctx = context.WithValue(ctx, contextKeyPortal, msg.Portal)
+	ctx = context.WithValue(ctx, contextKeyDiscordClient, session)
 	var req discordgo.MessageSend
 	req.Nonce = generateMessageNonce()
 	log := zerolog.Ctx(ctx)

pkg/msgconv/msgconv.go

@@ -17,35 +17,25 @@
 package msgconv
 
 import (
-	"context"
 	"math/rand"
 	"strconv"
 	"sync/atomic"
 
 	"maunium.net/go/mautrix/bridgev2"
-
-	"go.mau.fi/mautrix-discord/pkg/attachment"
 )
 
-type MediaReuploader func(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, reupload attachment.AttachmentReupload) (*attachment.ReuploadedAttachment, error)
-
 type MessageConverter struct {
 	Bridge *bridgev2.Bridge
 
 	nextDiscordUploadID atomic.Int32
 
-	// ReuploadMedia is called when the message converter wants to upload some
+	MaxFileSize int64
-	// media it is attempting to bridge.
-	//
-	// This can be directly forwarded to the ReuploadMedia method on DiscordConnector.
-	// The indirection is only necessary to prevent an import cycle.
-	ReuploadMedia MediaReuploader
 }
 
-func NewMessageConverter(bridge *bridgev2.Bridge, reuploader MediaReuploader) *MessageConverter {
+func NewMessageConverter(bridge *bridgev2.Bridge) *MessageConverter {
 	mc := &MessageConverter{
-		Bridge:        bridge,
+		Bridge:      bridge,
-		ReuploadMedia: reuploader,
+		MaxFileSize: 50 * 1024 * 1024,
 	}
 
 	mc.nextDiscordUploadID.Store(rand.Int31n(100))