message, retry: include error code in retry receipt

Author: purpshell

internals.go

@@ -379,16 +379,19 @@ func (cli *Client) decryptMessages(ctx context.Context, info *types.MessageInfo,
 				return
 			}
 			isUnavailable := encType == "skmsg" && !containsDirectMsg && errors.Is(err, signalerror.ErrNoSenderKeyForUser)
+
+			retryReason := getRetryReasonFromError(err)
+
 			if encType == "msmsg" {
 				cli.backgroundIfAsyncAck(func() {
 					cli.sendAck(node, NackMissingMessageSecret)
 				})
 			} else if cli.SynchronousAck {
-				cli.sendRetryReceipt(ctx, node, info, isUnavailable)
+				cli.sendRetryReceipt(ctx, node, info, isUnavailable, retryReason)
 				// TODO this probably isn't supposed to ack
 				cli.sendAck(node, 0)
 			} else {
-				go cli.sendRetryReceipt(context.WithoutCancel(ctx), node, info, isUnavailable)
+				go cli.sendRetryReceipt(context.WithoutCancel(ctx), node, info, isUnavailable, retryReason)
 				go cli.sendAck(node, 0)
 			}
 			cli.dispatchEvent(&events.UndecryptableMessage{

message.go

@@ -11,7 +11,9 @@ import (
 	"crypto/hmac"
 	"crypto/sha256"
 	"encoding/binary"
+	"errors"
 	"fmt"
+	"go.mau.fi/libsignal/signalerror"
 	"time"
 
 	"go.mau.fi/libsignal/ecc"
@@ -43,6 +45,48 @@ type RecentMessage struct {
 	fb *waMsgApplication.MessageApplication
 }
 
+var (
+	RetryReasonUnknownError                 = 0
+	RetryReasonSignalErrorNoSession         = 1
+	RetryReasonSignalErrorInvalidKey        = 2
+	RetryReasonSignalErrorInvalidKeyId      = 3
+	RetryReasonSignalErrorInvalidMessage    = 4
+	RetryReasonSignalErrorInvalidSignature  = 5
+	RetryReasonSignalErrorFutureMessage     = 6
+	RetryReasonSignalErrorBadMac            = 7
+	RetryReasonSignalErrorInvalidSession    = 8
+	RetryReasonSignalErrorInvalidMsgKey     = 9
+	RetryReasonBadBroadcastEphemeralSetting = 10
+	RetryReasonUnknownCompanionNoPrekey     = 11
+	RetryReasonAdvFailure                   = 12
+	RetryReasonStatusRevokeDelay            = 13
+)
+
+func getRetryReasonFromError(err error) int {
+	switch {
+	case errors.Is(err, signalerror.ErrBadMAC):
+		return RetryReasonSignalErrorBadMac
+	case errors.Is(err, signalerror.ErrNoSessionForUser):
+	case errors.Is(err, signalerror.ErrNoSenderKeyForUser):
+		return RetryReasonSignalErrorNoSession
+	case errors.Is(err, signalerror.ErrWrongMessageVersion):
+	case errors.Is(err, signalerror.ErrOldMessageVersion):
+	case errors.Is(err, signalerror.ErrUnknownMessageVersion):
+	case errors.Is(err, signalerror.ErrIncompleteMessage):
+		return RetryReasonSignalErrorInvalidMessage
+	case errors.Is(err, signalerror.ErrInvalidSignature):
+	case errors.Is(err, signalerror.ErrSenderKeyStateVerificationFailed):
+		return RetryReasonSignalErrorInvalidSignature
+	case errors.Is(err, signalerror.ErrNoSignedPreKey):
+		return RetryReasonSignalErrorInvalidKey
+	case errors.Is(err, signalerror.ErrNoSenderKeyStateForID):
+		return RetryReasonSignalErrorInvalidKeyId
+	case errors.Is(err, signalerror.ErrTooFarIntoFuture):
+		return RetryReasonSignalErrorFutureMessage
+	}
+	return RetryReasonUnknownError
+}
+
 func (rm RecentMessage) IsEmpty() bool {
 	return rm.wa == nil && rm.fb == nil
 }
@@ -376,7 +420,7 @@ func (cli *Client) clearDelayedMessageRequests() {
 }
 
 // sendRetryReceipt sends a retry receipt for an incoming message.
-func (cli *Client) sendRetryReceipt(ctx context.Context, node *waBinary.Node, info *types.MessageInfo, forceIncludeIdentity bool) {
+func (cli *Client) sendRetryReceipt(ctx context.Context, node *waBinary.Node, info *types.MessageInfo, forceIncludeIdentity bool, errorCode int) {
 	id, _ := node.Attrs["id"].(string)
 	children := node.GetChildren()
 	var retryCountInMsg int
@@ -421,6 +465,7 @@ func (cli *Client) sendRetryReceipt(ctx context.Context, node *waBinary.Node, in
 				"id":    id,
 				"t":     node.Attrs["t"],
 				"v":     1,
+				"error": errorCode, // this can be 0 for the case of Unknown reason
 			}},
 			{Tag: "registration", Content: registrationIDBytes[:]},
 		},