mautrix-whatsapp/crypto.go
2020-08-05 14:58:46 +03:00

279 lines
8.9 KiB
Go

// mautrix-whatsapp - A Matrix-WhatsApp puppeting bridge.
// Copyright (C) 2020 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/>.
// +build cgo,!nocrypto
package main
import (
"crypto/hmac"
"crypto/sha512"
"encoding/hex"
"fmt"
"time"
"github.com/pkg/errors"
"maunium.net/go/maulogger/v2"
"maunium.net/go/mautrix"
"maunium.net/go/mautrix/crypto"
"maunium.net/go/mautrix/event"
"maunium.net/go/mautrix/id"
"maunium.net/go/mautrix-whatsapp/database"
)
var levelTrace = maulogger.Level{
Name: "Trace",
Severity: -10,
Color: -1,
}
type CryptoHelper struct {
bridge *Bridge
client *mautrix.Client
mach *crypto.OlmMachine
store *database.SQLCryptoStore
log maulogger.Logger
baseLog maulogger.Logger
}
func NewCryptoHelper(bridge *Bridge) Crypto {
if !bridge.Config.Bridge.Encryption.Allow {
bridge.Log.Debugln("Bridge built with end-to-bridge encryption, but disabled in config")
return nil
} else if bridge.Config.Bridge.LoginSharedSecret == "" {
bridge.Log.Warnln("End-to-bridge encryption enabled, but login_shared_secret not set")
return nil
}
baseLog := bridge.Log.Sub("Crypto")
return &CryptoHelper{
bridge: bridge,
log: baseLog.Sub("Helper"),
baseLog: baseLog,
}
}
func (helper *CryptoHelper) Init() error {
helper.log.Debugln("Initializing end-to-bridge encryption...")
helper.store = database.NewSQLCryptoStore(helper.bridge.DB, helper.bridge.AS.BotMXID(),
fmt.Sprintf("@%s:%s", helper.bridge.Config.Bridge.FormatUsername("%"), helper.bridge.AS.HomeserverDomain))
var err error
helper.client, err = helper.loginBot()
if err != nil {
return err
}
helper.log.Debugln("Logged in as bridge bot with device ID", helper.client.DeviceID)
logger := &cryptoLogger{helper.baseLog}
stateStore := &cryptoStateStore{helper.bridge}
helper.mach = crypto.NewOlmMachine(helper.client, logger, helper.store, stateStore)
helper.mach.AllowKeyShare = helper.allowKeyShare
helper.client.Logger = logger.int.Sub("Bot")
helper.client.Syncer = &cryptoSyncer{helper.mach}
helper.client.Store = &cryptoClientStore{helper.store}
return helper.mach.Load()
}
func (helper *CryptoHelper) allowKeyShare(device *crypto.DeviceIdentity, info event.RequestedKeyInfo) *crypto.KeyShareRejection {
cfg := helper.bridge.Config.Bridge.Encryption.KeySharing
if !cfg.Allow {
return &crypto.KeyShareRejectNoResponse
} else if device.Trust == crypto.TrustStateBlacklisted {
return &crypto.KeyShareRejectBlacklisted
} else if device.Trust == crypto.TrustStateVerified || !cfg.RequireVerification {
portal := helper.bridge.GetPortalByMXID(info.RoomID)
if portal == nil {
helper.log.Debugfln("Rejecting key request for %s from %s/%s: room is not a portal", info.SessionID, device.UserID, device.DeviceID)
return &crypto.KeyShareRejection{Code: event.RoomKeyWithheldUnavailable, Reason: "Requested room is not a portal room"}
}
user := helper.bridge.GetUserByMXID(device.UserID)
if !user.IsInPortal(portal.Key) {
helper.log.Debugfln("Rejecting key request for %s from %s/%s: user is not in portal", info.SessionID, device.UserID, device.DeviceID)
return &crypto.KeyShareRejection{Code: event.RoomKeyWithheldUnauthorized, Reason: "You're not in that portal"}
}
helper.log.Debugfln("Accepting key request for %s from %s/%s", info.SessionID, device.UserID, device.DeviceID)
return nil
} else {
return &crypto.KeyShareRejectUnverified
}
}
func (helper *CryptoHelper) loginBot() (*mautrix.Client, error) {
deviceID := helper.store.FindDeviceID()
if len(deviceID) > 0 {
helper.log.Debugln("Found existing device ID for bot in database:", deviceID)
}
mac := hmac.New(sha512.New, []byte(helper.bridge.Config.Bridge.LoginSharedSecret))
mac.Write([]byte(helper.bridge.AS.BotMXID()))
client, err := mautrix.NewClient(helper.bridge.AS.HomeserverURL, "", "")
if err != nil {
return nil, err
}
resp, err := client.Login(&mautrix.ReqLogin{
Type: "m.login.password",
Identifier: mautrix.UserIdentifier{Type: "m.id.user", User: string(helper.bridge.AS.BotMXID())},
Password: hex.EncodeToString(mac.Sum(nil)),
DeviceID: deviceID,
InitialDeviceDisplayName: "WhatsApp Bridge",
StoreCredentials: true,
})
if err != nil {
return nil, err
}
if len(deviceID) == 0 {
helper.store.DeviceID = resp.DeviceID
}
return client, nil
}
func (helper *CryptoHelper) Start() {
helper.log.Debugln("Starting syncer for receiving to-device messages")
err := helper.client.Sync()
if err != nil {
helper.log.Errorln("Fatal error syncing:", err)
}
}
func (helper *CryptoHelper) Stop() {
helper.client.StopSync()
}
func (helper *CryptoHelper) Decrypt(evt *event.Event) (*event.Event, error) {
return helper.mach.DecryptMegolmEvent(evt)
}
func (helper *CryptoHelper) Encrypt(roomID id.RoomID, evtType event.Type, content event.Content) (*event.EncryptedEventContent, error) {
encrypted, err := helper.mach.EncryptMegolmEvent(roomID, evtType, &content)
if err != nil {
if err != crypto.SessionExpired && err != crypto.SessionNotShared && err != crypto.NoGroupSession {
return nil, err
}
helper.log.Debugfln("Got %v while encrypting event for %s, sharing group session and trying again...", err, roomID)
users, err := helper.store.GetRoomMembers(roomID)
if err != nil {
return nil, errors.Wrap(err, "failed to get room member list")
}
err = helper.mach.ShareGroupSession(roomID, users)
if err != nil {
return nil, errors.Wrap(err, "failed to share group session")
}
encrypted, err = helper.mach.EncryptMegolmEvent(roomID, evtType, &content)
if err != nil {
return nil, errors.Wrap(err, "failed to encrypt event after re-sharing group session")
}
}
return encrypted, nil
}
func (helper *CryptoHelper) HandleMemberEvent(evt *event.Event) {
helper.mach.HandleMemberEvent(evt)
}
type cryptoSyncer struct {
*crypto.OlmMachine
}
func (syncer *cryptoSyncer) ProcessResponse(resp *mautrix.RespSync, since string) error {
syncer.ProcessSyncResponse(resp, since)
return nil
}
func (syncer *cryptoSyncer) OnFailedSync(_ *mautrix.RespSync, err error) (time.Duration, error) {
syncer.Log.Error("Error /syncing, waiting 10 seconds: %v", err)
return 10 * time.Second, nil
}
func (syncer *cryptoSyncer) GetFilterJSON(_ id.UserID) *mautrix.Filter {
everything := []event.Type{{Type: "*"}}
return &mautrix.Filter{
Presence: mautrix.FilterPart{NotTypes: everything},
AccountData: mautrix.FilterPart{NotTypes: everything},
Room: mautrix.RoomFilter{
IncludeLeave: false,
Ephemeral: mautrix.FilterPart{NotTypes: everything},
AccountData: mautrix.FilterPart{NotTypes: everything},
State: mautrix.FilterPart{NotTypes: everything},
Timeline: mautrix.FilterPart{NotTypes: everything},
},
}
}
type cryptoLogger struct {
int maulogger.Logger
}
func (c *cryptoLogger) Error(message string, args ...interface{}) {
c.int.Errorfln(message, args...)
}
func (c *cryptoLogger) Warn(message string, args ...interface{}) {
c.int.Warnfln(message, args...)
}
func (c *cryptoLogger) Debug(message string, args ...interface{}) {
c.int.Debugfln(message, args...)
}
func (c *cryptoLogger) Trace(message string, args ...interface{}) {
c.int.Logfln(levelTrace, message, args...)
}
type cryptoClientStore struct {
int *database.SQLCryptoStore
}
func (c cryptoClientStore) SaveFilterID(_ id.UserID, _ string) {}
func (c cryptoClientStore) LoadFilterID(_ id.UserID) string { return "" }
func (c cryptoClientStore) SaveRoom(_ *mautrix.Room) {}
func (c cryptoClientStore) LoadRoom(_ id.RoomID) *mautrix.Room { return nil }
func (c cryptoClientStore) SaveNextBatch(_ id.UserID, nextBatchToken string) {
c.int.PutNextBatch(nextBatchToken)
}
func (c cryptoClientStore) LoadNextBatch(_ id.UserID) string {
return c.int.GetNextBatch()
}
var _ mautrix.Storer = (*cryptoClientStore)(nil)
type cryptoStateStore struct {
bridge *Bridge
}
var _ crypto.StateStore = (*cryptoStateStore)(nil)
func (c *cryptoStateStore) IsEncrypted(id id.RoomID) bool {
portal := c.bridge.GetPortalByMXID(id)
if portal != nil {
return portal.Encrypted
}
return false
}
func (c *cryptoStateStore) FindSharedRooms(id id.UserID) []id.RoomID {
return c.bridge.StateStore.FindSharedRooms(id)
}
func (c *cryptoStateStore) GetEncryptionEvent(id.RoomID) *event.EncryptionEventContent {
// TODO implement
return nil
}