handlematrix: bridge outgoing message attachments

pkg/connector/capabilities.go

@@ -54,6 +54,13 @@ func capID() string {
 	return base
 }
 
+// TODO: This limit is increased depending on user subscription status (Discord Nitro).
+const MaxTextLength = 2000
+
+// TODO: This limit is increased depending on user subscription status (Discord Nitro).
+// TODO: Verify this figure (10 MiB).
+const MaxFileSize = 10485760
+
 var discordCaps = &event.RoomFeatures{
 	ID:       capID(),
 	Reply:    event.CapLevelFullySupported,
@@ -78,9 +85,57 @@ var discordCaps = &event.RoomFeatures{
 		event.FmtListJumpValue:      event.CapLevelUnsupported,
 		event.FmtCustomEmoji:        event.CapLevelUnsupported, // TODO: Support.
 	},
+	File: event.FileFeatureMap{
+		event.MsgImage: {
+			MimeTypes: map[string]event.CapabilitySupportLevel{
+				"image/jpeg": event.CapLevelFullySupported,
+				"image/png":  event.CapLevelFullySupported,
+				"image/gif":  event.CapLevelFullySupported,
+				"image/webp": event.CapLevelFullySupported,
+			},
+			Caption:          event.CapLevelFullySupported,
+			MaxCaptionLength: MaxTextLength,
+			MaxSize:          MaxFileSize,
+		},
+		event.MsgVideo: {
+			MimeTypes: map[string]event.CapabilitySupportLevel{
+				"video/mp4":  event.CapLevelFullySupported,
+				"video/webm": event.CapLevelFullySupported,
+			},
+			Caption:          event.CapLevelFullySupported,
+			MaxCaptionLength: MaxTextLength,
+			MaxSize:          MaxFileSize,
+		},
+		event.MsgAudio: {
+			MimeTypes: map[string]event.CapabilitySupportLevel{
+				"audio/mpeg": event.CapLevelFullySupported,
+				"audio/webm": event.CapLevelFullySupported,
+				"audio/wav":  event.CapLevelFullySupported,
+			},
+			Caption:          event.CapLevelFullySupported,
+			MaxCaptionLength: MaxTextLength,
+			MaxSize:          MaxFileSize,
+		},
+		event.MsgFile: {
+			MimeTypes: map[string]event.CapabilitySupportLevel{
+				"*/*": event.CapLevelFullySupported,
+			},
+			Caption:          event.CapLevelFullySupported,
+			MaxCaptionLength: MaxTextLength,
+			MaxSize:          MaxFileSize,
+		},
+		event.CapMsgGIF: {
+			MimeTypes: map[string]event.CapabilitySupportLevel{
+				"image/gif": event.CapLevelFullySupported,
+			},
+			Caption:          event.CapLevelFullySupported,
+			MaxCaptionLength: MaxTextLength,
+			MaxSize:          MaxFileSize,
+		},
+		// TODO: Support voice messages.
+	},
 	LocationMessage: event.CapLevelUnsupported,
-	// TODO: This limit is increased depending on Discord subscription (Nitro).
+	MaxTextLength:   MaxTextLength,
-	MaxTextLength: 2000,
 	// TODO: Support reactions.
 	// TODO: Support threads.
 	// TODO: Support editing.

pkg/connector/client.go

@@ -33,7 +33,6 @@ import (
 	"maunium.net/go/mautrix/bridgev2/status"
 
 	"go.mau.fi/mautrix-discord/pkg/discordid"
-	"go.mau.fi/mautrix-discord/pkg/msgconv"
 )
 
 type DiscordClient struct {
@@ -42,7 +41,6 @@ type DiscordClient struct {
 	UserLogin       *bridgev2.UserLogin
 	Session         *discordgo.Session
 	hasBegunSyncing bool
-	MsgConv         msgconv.MessageConverter
 }
 
 func (d *DiscordConnector) LoadUserLogin(ctx context.Context, login *bridgev2.UserLogin) error {
@@ -59,10 +57,6 @@ func (d *DiscordConnector) LoadUserLogin(ctx context.Context, login *bridgev2.Us
 		connector: d,
 		UserLogin: login,
 		Session:   session,
-		MsgConv: msgconv.MessageConverter{
-			Bridge:        d.Bridge,
-			ReuploadMedia: d.ReuploadMedia,
-		},
 	}
 	cl.SetUp(ctx, meta)
 

pkg/connector/connector.go

@@ -33,10 +33,7 @@ var _ bridgev2.NetworkConnector = (*DiscordConnector)(nil)
 
 func (d *DiscordConnector) Init(bridge *bridgev2.Bridge) {
 	d.Bridge = bridge
-	d.MsgConv = &msgconv.MessageConverter{
+	d.MsgConv = msgconv.NewMessageConverter(bridge, d.ReuploadMedia)
-		Bridge:        bridge,
-		ReuploadMedia: d.ReuploadMedia,
-	}
 }
 
 func (d *DiscordConnector) Start(ctx context.Context) error {

pkg/connector/handlematrix.go

@@ -20,6 +20,7 @@ import (
 	"context"
 
 	"github.com/bwmarrin/discordgo"
+	"github.com/rs/zerolog"
 	"maunium.net/go/mautrix/bridgev2"
 	"maunium.net/go/mautrix/bridgev2/database"
 	"maunium.net/go/mautrix/bridgev2/networkid"
@@ -41,7 +42,7 @@ func (d *DiscordClient) HandleMatrixMessage(ctx context.Context, msg *bridgev2.M
 	portal := msg.Portal
 	channelID := string(portal.ID)
 
-	sendReq, err := d.connector.MsgConv.ToDiscord(ctx, msg)
+	sendReq, err := d.connector.MsgConv.ToDiscord(ctx, d.Session, msg)
 	if err != nil {
 		return nil, err
 	}
@@ -51,7 +52,7 @@ func (d *DiscordClient) HandleMatrixMessage(ctx context.Context, msg *bridgev2.M
 	// TODO: Pass the guild ID when send messages in guild channels.
 	options = append(options, discordgo.WithChannelReferer("", channelID))
 
-	sentMsg, err := d.Session.ChannelMessageSendComplex(string(msg.Portal.ID), &sendReq, options...)
+	sentMsg, err := d.Session.ChannelMessageSendComplex(string(msg.Portal.ID), sendReq, options...)
 	if err != nil {
 		return nil, err
 	}

pkg/msgconv/from-matrix.go

@@ -17,12 +17,16 @@
 package msgconv
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"io"
+	"net/http"
 	"strconv"
 	"time"
 
 	"github.com/bwmarrin/discordgo"
+	"github.com/rs/zerolog"
 	"go.mau.fi/util/variationselector"
 	"maunium.net/go/mautrix/bridgev2"
 	"maunium.net/go/mautrix/event"
@@ -59,14 +63,43 @@ func parseAllowedLinkPreviews(raw map[string]any) []string {
 	return allowedLinkPreviews
 }
 
+func uploadDiscordAttachment(cli *http.Client, url string, data []byte) error {
+	req, err := http.NewRequest(http.MethodPut, url, bytes.NewReader(data))
+	if err != nil {
+		return err
+	}
+
+	for key, value := range discordgo.DroidBaseHeaders {
+		req.Header.Set(key, value)
+	}
+	req.Header.Set("Content-Type", "application/octet-stream")
+	req.Header.Set("Referer", "https://discord.com/")
+	req.Header.Set("Sec-Fetch-Dest", "empty")
+	req.Header.Set("Sec-Fetch-Mode", "cors")
+	req.Header.Set("Sec-Fetch-Site", "cross-site")
+
+	resp, err := cli.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode > 300 {
+		respData, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("unexpected status %d: %s", resp.StatusCode, respData)
+	}
+	return nil
+}
+
 // ToDiscord converts a Matrix message into a discordgo.MessageSend that is appropriate
 // for bridging the message to Discord.
 func (mc *MessageConverter) ToDiscord(
 	ctx context.Context,
+	session *discordgo.Session,
 	msg *bridgev2.MatrixMessage,
-) (discordgo.MessageSend, error) {
+) (*discordgo.MessageSend, error) {
 	var req discordgo.MessageSend
 	req.Nonce = generateMessageNonce()
+	log := zerolog.Ctx(ctx)
 
 	if msg.ReplyTo != nil {
 		req.Reference = &discordgo.MessageReference{
@@ -75,18 +108,73 @@ func (mc *MessageConverter) ToDiscord(
 		}
 	}
 
-	switch msg.Content.MsgType {
+	portal := msg.Portal
-	case event.MsgText, event.MsgEmote, event.MsgNotice:
+	channelID := string(portal.ID)
-		req.Content, req.AllowedMentions = mc.convertMatrixMessageContent(ctx, msg.Portal, msg.Content, parseAllowedLinkPreviews(msg.Event.Content.Raw))
+	content := msg.Content
-		if msg.Content.MsgType == event.MsgEmote {
+
+	convertMatrix := func() {
+		req.Content, req.AllowedMentions = mc.convertMatrixMessageContent(ctx, msg.Portal, content, parseAllowedLinkPreviews(msg.Event.Content.Raw))
+		if content.MsgType == event.MsgEmote {
 			req.Content = fmt.Sprintf("_%s_", req.Content)
 		}
-		// TODO: Handle attachments.
+	}
+
+	switch content.MsgType {
+	case event.MsgText, event.MsgEmote, event.MsgNotice:
+		convertMatrix()
+	case event.MsgAudio, event.MsgFile, event.MsgVideo:
+		mediaData, err := mc.Bridge.Bot.DownloadMedia(ctx, content.URL, content.File)
+		if err != nil {
+			log.Err(err).Msg("Failed to download Matrix attachment for bridging")
+			return nil, bridgev2.ErrMediaDownloadFailed
+		}
+
+		filename := content.Body
+		if content.FileName != "" && content.FileName != content.Body {
+			filename = content.FileName
+			convertMatrix()
+		}
+		if msg.Event.Content.Raw["page.codeberg.everypizza.msc4193.spoiler"] == true {
+			filename = "SPOILER_" + filename
+		}
+
+		// TODO: Support attachments for relay/webhook. (A branch was removed here.)
+		att := &discordgo.MessageAttachment{
+			ID:       "0",
+			Filename: filename,
+		}
+
+		upload_id := mc.NextDiscordUploadID()
+		log.Debug().Str("upload_id", upload_id).Msg("Preparing attachment")
+		prep, err := session.ChannelAttachmentCreate(channelID, &discordgo.ReqPrepareAttachments{
+			Files: []*discordgo.FilePrepare{{
+				Size: len(mediaData),
+				Name: att.Filename,
+				ID:   mc.NextDiscordUploadID(),
+			}},
+			// TODO: Populate with guild ID. Support threads.
+		}, discordgo.WithChannelReferer("", channelID))
+
+		if err != nil {
+			log.Err(err).Msg("Failed to create attachment in preparation for attachment reupload")
+			return nil, bridgev2.ErrMediaReuploadFailed
+		}
+
+		prepared := prep.Attachments[0]
+		att.UploadedFilename = prepared.UploadFilename
+
+		err = uploadDiscordAttachment(session.Client, prepared.UploadURL, mediaData)
+		if err != nil {
+			log.Err(err).Msg("Failed to reupload Discord attachment after preparing")
+			return nil, bridgev2.ErrMediaReuploadFailed
+		}
+
+		req.Attachments = append(req.Attachments, att)
 	}
 
 	// TODO: Handle (silent) replies and allowed mentions.
 
-	return req, nil
+	return &req, nil
 }
 
 func (mc *MessageConverter) convertMatrixMessageContent(ctx context.Context, portal *bridgev2.Portal, content *event.MessageEventContent, allowedLinkPreviews []string) (string, *discordgo.MessageAllowedMentions) {

pkg/msgconv/msgconv.go

@@ -18,19 +18,41 @@ 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
 	// 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 func(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, reupload attachment.AttachmentReupload) (*attachment.ReuploadedAttachment, error)
+	ReuploadMedia MediaReuploader
+}
+
+func NewMessageConverter(bridge *bridgev2.Bridge, reuploader MediaReuploader) *MessageConverter {
+	mc := &MessageConverter{
+		Bridge:        bridge,
+		ReuploadMedia: reuploader,
+	}
+
+	mc.nextDiscordUploadID.Store(rand.Int31n(100))
+	return mc
+}
+
+func (mc *MessageConverter) NextDiscordUploadID() string {
+	val := mc.nextDiscordUploadID.Add(2)
+	return strconv.Itoa(int(val))
 }