Files
mautrix-discord/pkg/connector/attachments.go
Skip R 86e18c1f7d msgconv: port the majority of embed and attachment bridging
We still need to implement direct media support, so for now we encrypt
and reupload to Matrix. Notably remaining is conversion to HTML.
2025-11-26 15:18:29 -08:00

127 lines
3.9 KiB
Go

// 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 connector
import (
"context"
"errors"
"fmt"
"io"
"net/http"
"net/url"
"path"
"strconv"
"github.com/bwmarrin/discordgo"
"github.com/rs/zerolog"
"maunium.net/go/mautrix/bridgev2"
"maunium.net/go/mautrix/event"
"maunium.net/go/mautrix/id"
)
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
}
}
type AttachmentReupload struct {
DownloadingURL string
FileName string
MimeType string
}
type ReuploadedAttachment struct {
AttachmentReupload
DownloadedSize int
MXC id.ContentURIString
EncryptedFile *event.EncryptedFileInfo
}
func (d *DiscordConnector) ReuploadMedia(ctx context.Context, intent bridgev2.MatrixAPI, portal *bridgev2.Portal, upload AttachmentReupload) (*ReuploadedAttachment, error) {
log := zerolog.Ctx(ctx)
// 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
log.Trace().Str("detected_file_name", fileName).Msg("Inferred the file name of the media we're reuploading")
}
if upload.MimeType == "" {
mime := http.DetectContentType(data)
upload.MimeType = mime
log.Trace().Str("detected_mime_type", mime).Msg("Inferred the mime type of the media we're reuploading")
}
log.Trace().Stringer("portal_mxid", portal.MXID).
Int("attachment_size", len(data)).
Str("file_name", upload.FileName).
Str("mime_type", upload.MimeType).
Msg("Uploading downloaded media")
mxc, file, err := intent.UploadMedia(ctx, portal.MXID, data, upload.FileName, upload.MimeType)
if err != nil {
return nil, err
}
return &ReuploadedAttachment{
AttachmentReupload: upload,
DownloadedSize: len(data),
MXC: mxc,
EncryptedFile: file,
}, nil
}