Redo direct media access with URL refreshing (#135)
This commit is contained in:
Tulir Asokan
GitHub
287
directmedia_id.go
Normal file
287
directmedia_id.go
Normal file
@@ -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,
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user