Add internal counter for retry requests

Apparently some people have broken (possibly unofficial) clients which don't
increment the counter on outgoing requests like whatsmeow and official clients
do, so need to keep track of the count and ignore requests if the sender spams
them.

client.go

@@ -93,6 +93,9 @@ type Client struct {
 	messageRetries     map[string]int
 	messageRetriesLock sync.Mutex
 
+	incomingRetryRequestCounter     map[incomingRetryKey]int
+	incomingRetryRequestCounterLock sync.Mutex
+
 	appStateKeyRequests     map[string]time.Time
 	appStateKeyRequestsLock sync.RWMutex
 
@@ -186,6 +189,8 @@ func NewClient(deviceStore *store.Device, log waLog.Logger) *Client {
 		appStateProc:    appstate.NewProcessor(deviceStore, log.Sub("AppState")),
 		socketWait:      make(chan struct{}),
 
+		incomingRetryRequestCounter: make(map[incomingRetryKey]int),
+
 		historySyncNotifications: make(chan *waProto.HistorySyncNotification, 32),
 
 		groupParticipantsCache: make(map[types.JID][]types.JID),

retry.go

@@ -94,6 +94,11 @@ func (cli *Client) shouldRecreateSession(retryCount int, jid types.JID) (reason
 	return "", false
 }
 
+type incomingRetryKey struct {
+	jid       types.JID
+	messageID types.MessageID
+}
+
 // handleRetryReceipt handles an incoming retry receipt for an outgoing message.
 func (cli *Client) handleRetryReceipt(receipt *events.Receipt, node *waBinary.Node) error {
 	retryChild, ok := node.GetOptionalChildByTag("retry")
@@ -111,6 +116,17 @@ func (cli *Client) handleRetryReceipt(receipt *events.Receipt, node *waBinary.No
 	if err != nil {
 		return err
 	}
+
+	retryKey := incomingRetryKey{receipt.Sender, messageID}
+	cli.incomingRetryRequestCounterLock.Lock()
+	cli.incomingRetryRequestCounter[retryKey]++
+	internalCounter := cli.incomingRetryRequestCounter[retryKey]
+	cli.incomingRetryRequestCounterLock.Unlock()
+	if internalCounter >= 10 {
+		cli.Log.Warnf("Dropping retry request from %s for %s: internal retry counter is %d", messageID, receipt.Sender, internalCounter)
+		return nil
+	}
+
 	ownID := cli.getOwnID()
 	if ownID.IsEmpty() {
 		return ErrNotLoggedIn