Reorganize code so that we can send Multi Part Payments:

- LNWorker is notified about htlc events and creates payment events.
 - LNWorker._pay is a while loop that calls create_routes_from_invoice.
 - create_route_from_invoices should decide whether to split the payment,
   using graph knowledge and feedback from previous attempts (not in this commit)
 - data structures for payment logs are simplified into a single type, HtlcLog

electrum/gui/qt/channel_details.py

@@ -82,8 +82,8 @@ class ChannelDetailsDialog(QtWidgets.QDialog):
         dest_mapping = self.keyname_rows[to]
         dest_mapping[payment_hash] = len(dest_mapping)
 
-    ln_payment_completed = QtCore.pyqtSignal(str, bytes, bytes)
-    ln_payment_failed = QtCore.pyqtSignal(str, bytes, bytes)
+    htlc_fulfilled = QtCore.pyqtSignal(str, bytes, bytes)
+    htlc_failed = QtCore.pyqtSignal(str, bytes, bytes)
     htlc_added = QtCore.pyqtSignal(str, Channel, UpdateAddHtlc, Direction)
     state_changed = QtCore.pyqtSignal(str, Abstract_Wallet, AbstractChannel)
 
@@ -95,7 +95,7 @@ class ChannelDetailsDialog(QtWidgets.QDialog):
             self.update()
 
     @QtCore.pyqtSlot(str, Channel, UpdateAddHtlc, Direction)
-    def do_htlc_added(self, evtname, chan, htlc, direction):
+    def on_htlc_added(self, evtname, chan, htlc, direction):
         if chan != self.chan:
             return
         mapping = self.keyname_rows['inflight']
@@ -103,14 +103,14 @@ class ChannelDetailsDialog(QtWidgets.QDialog):
         self.folders['inflight'].appendRow(self.make_htlc_item(htlc, direction))
 
     @QtCore.pyqtSlot(str, bytes, bytes)
-    def do_ln_payment_completed(self, evtname, payment_hash, chan_id):
+    def on_htlc_fulfilled(self, evtname, payment_hash, chan_id):
         if chan_id != self.chan.channel_id:
             return
         self.move('inflight', 'settled', payment_hash)
         self.update()
 
     @QtCore.pyqtSlot(str, bytes, bytes)
-    def do_ln_payment_failed(self, evtname, payment_hash, chan_id):
+    def on_htlc_failed(self, evtname, payment_hash, chan_id):
         if chan_id != self.chan.channel_id:
             return
         self.move('inflight', 'failed', payment_hash)
@@ -137,14 +137,14 @@ class ChannelDetailsDialog(QtWidgets.QDialog):
         self.format_msat = lambda msat: window.format_amount_and_units(msat / 1000)
 
         # connect signals with slots
-        self.ln_payment_completed.connect(self.do_ln_payment_completed)
-        self.ln_payment_failed.connect(self.do_ln_payment_failed)
+        self.htlc_fulfilled.connect(self.on_htlc_fulfilled)
+        self.htlc_failed.connect(self.on_htlc_failed_failed)
         self.state_changed.connect(self.do_state_changed)
-        self.htlc_added.connect(self.do_htlc_added)
+        self.htlc_added.connect(self.on_htlc_added)
 
         # register callbacks for updating
-        util.register_callback(self.ln_payment_completed.emit, ['ln_payment_completed'])
-        util.register_callback(self.ln_payment_failed.emit, ['ln_payment_failed'])
+        util.register_callback(self.htlc_fulfilled.emit, ['htlc_fulfilled'])
+        util.register_callback(self.htlc_failed.emit, ['htlc_failed'])
         util.register_callback(self.htlc_added.emit, ['htlc_added'])
         util.register_callback(self.state_changed.emit, ['channel'])
 

electrum/gui/qt/invoice_list.py

@@ -34,7 +34,7 @@ from PyQt5.QtWidgets import QMenu, QVBoxLayout, QTreeWidget, QTreeWidgetItem, QH
 from electrum.i18n import _
 from electrum.util import format_time
 from electrum.invoices import Invoice, PR_UNPAID, PR_PAID, PR_INFLIGHT, PR_FAILED, PR_TYPE_ONCHAIN, PR_TYPE_LN
-from electrum.lnutil import PaymentAttemptLog
+from electrum.lnutil import HtlcLog
 
 from .util import MyTreeView, read_QIcon, MySortModel, pr_icons
 from .util import CloseButton, Buttons
@@ -173,7 +173,7 @@ class InvoiceList(MyTreeView):
         menu.addAction(_("Delete"), lambda: self.parent.delete_invoices([key]))
         menu.exec_(self.viewport().mapToGlobal(position))
 
-    def show_log(self, key, log: Sequence[PaymentAttemptLog]):
+    def show_log(self, key, log: Sequence[HtlcLog]):
         d = WindowModalDialog(self, _("Payment log"))
         d.setMinimumWidth(600)
         vbox = QVBoxLayout(d)

electrum/lnchannel.py

@@ -991,7 +991,7 @@ class Channel(AbstractChannel):
         if self.lnworker:
             sent = self.hm.sent_in_ctn(new_ctn)
             for htlc in sent:
-                self.lnworker.payment_sent(self, htlc.payment_hash)
+                self.lnworker.htlc_fulfilled(self, htlc.payment_hash, htlc.htlc_id, htlc.amount_msat)
             failed = self.hm.failed_in_ctn(new_ctn)
             for htlc in failed:
                 try:
@@ -1002,7 +1002,7 @@ class Channel(AbstractChannel):
                 if self.lnworker.get_payment_info(htlc.payment_hash) is None:
                     self.save_fail_htlc_reason(htlc.htlc_id, error_bytes, failure_message)
                 else:
-                    self.lnworker.payment_failed(self, htlc.payment_hash, error_bytes, failure_message)
+                    self.lnworker.htlc_failed(self, htlc.payment_hash, htlc.htlc_id, htlc.amount_msat, error_bytes, failure_message)
 
     def save_fail_htlc_reason(
             self,
@@ -1048,9 +1048,9 @@ class Channel(AbstractChannel):
         info = self.lnworker.get_payment_info(payment_hash)
         if info is not None and info.status != PR_PAID:
             if is_sent:
-                self.lnworker.payment_sent(self, payment_hash)
+                self.lnworker.htlc_fulfilled(self, payment_hash, htlc.htlc_id, htlc.amount_msat)
             else:
-                self.lnworker.payment_received(payment_hash)
+                self.lnworker.htlc_received(self, payment_hash)
 
     def balance(self, whose: HTLCOwner, *, ctx_owner=HTLCOwner.LOCAL, ctn: int = None) -> int:
         assert type(whose) is HTLCOwner

electrum/lnutil.py

@@ -249,52 +249,36 @@ class Outpoint(StoredObject):
         return "{}:{}".format(self.txid, self.output_index)
 
 
-class PaymentAttemptFailureDetails(NamedTuple):
-    sender_idx: Optional[int]
-    failure_msg: 'OnionRoutingFailureMessage'
-    is_blacklisted: bool
-
-
-class PaymentAttemptLog(NamedTuple):
+class HtlcLog(NamedTuple):
     success: bool
+    amount_msat: int
     route: Optional['LNPaymentRoute'] = None
     preimage: Optional[bytes] = None
-    failure_details: Optional[PaymentAttemptFailureDetails] = None
-    exception: Optional[Exception] = None
+    error_bytes: Optional[bytes] = None
+    failure_msg: Optional['OnionRoutingFailureMessage'] = None
+    sender_idx: Optional[int] = None
 
     def formatted_tuple(self):
-        if not self.exception:
-            route = self.route
-            route_str = '%d'%len(route)
-            short_channel_id = None
-            if not self.success:
-                sender_idx = self.failure_details.sender_idx
-                failure_msg = self.failure_details.failure_msg
-                if sender_idx is not None:
-                    try:
-                        short_channel_id = route[sender_idx + 1].short_channel_id
-                    except IndexError:
-                        # payment destination reported error
-                        short_channel_id = _("Destination node")
-                message = failure_msg.code_name()
-            else:
-                short_channel_id = route[-1].short_channel_id
-                message = _('Success')
-            chan_str = str(short_channel_id) if short_channel_id else _("Unknown")
+        route = self.route
+        route_str = '%d'%len(route)
+        short_channel_id = None
+        if not self.success:
+            sender_idx = self.sender_idx
+            failure_msg = self.failure_msg
+            if sender_idx is not None:
+                try:
+                    short_channel_id = route[sender_idx + 1].short_channel_id
+                except IndexError:
+                    # payment destination reported error
+                    short_channel_id = _("Destination node")
+            message = failure_msg.code_name()
         else:
-            route_str = 'None'
-            chan_str = 'N/A'
-            message = str(self.exception)
+            short_channel_id = route[-1].short_channel_id
+            message = _('Success')
+        chan_str = str(short_channel_id) if short_channel_id else _("Unknown")
         return route_str, chan_str, message
 
 
-class BarePaymentAttemptLog(NamedTuple):
-    success: bool
-    preimage: Optional[bytes] = None
-    error_bytes: Optional[bytes] = None
-    failure_message: Optional['OnionRoutingFailureMessage'] = None
-
-
 class LightningError(Exception): pass
 class LightningPeerConnectionClosed(LightningError): pass
 class UnableToDeriveSecret(LightningError): pass

electrum/lnworker.py

@@ -55,9 +55,8 @@ from .lnutil import (Outpoint, LNPeerAddr,
                      generate_keypair, LnKeyFamily, LOCAL, REMOTE,
                      MIN_FINAL_CLTV_EXPIRY_FOR_INVOICE,
                      NUM_MAX_EDGES_IN_PAYMENT_PATH, SENT, RECEIVED, HTLCOwner,
-                     UpdateAddHtlc, Direction, LnFeatures,
-                     ShortChannelID, PaymentAttemptLog, PaymentAttemptFailureDetails,
-                     BarePaymentAttemptLog, derive_payment_secret_from_payment_preimage)
+                     UpdateAddHtlc, Direction, LnFeatures, ShortChannelID,
+                     HtlcLog, derive_payment_secret_from_payment_preimage)
 from .lnutil import ln_dummy_address, ln_compare_features, IncompatibleLightningFeatures
 from .transaction import PartialTxOutput, PartialTransaction, PartialTxInput
 from .lnonion import OnionFailureCode, process_onion_packet, OnionPacket, OnionRoutingFailureMessage
@@ -570,7 +569,7 @@ class LNWallet(LNWorker):
         self.preimages = self.db.get_dict('lightning_preimages')   # RHASH -> preimage
         # note: this sweep_address is only used as fallback; as it might result in address-reuse
         self.sweep_address = wallet.get_new_sweep_address_for_channel()
-        self.logs = defaultdict(list)  # type: Dict[str, List[PaymentAttemptLog]]  # key is RHASH  # (not persisted)
+        self.logs = defaultdict(list)  # type: Dict[str, List[HtlcLog]]  # key is RHASH  # (not persisted)
         # used in tests
         self.enable_htlc_settle = asyncio.Event()
         self.enable_htlc_settle.set()
@@ -581,8 +580,11 @@ class LNWallet(LNWorker):
         for channel_id, c in random_shuffled_copy(channels.items()):
             self._channels[bfh(channel_id)] = Channel(c, sweep_address=self.sweep_address, lnworker=self)
 
-        self.pending_payments = defaultdict(asyncio.Future)  # type: Dict[bytes, asyncio.Future[BarePaymentAttemptLog]]
+        self.pending_payments = defaultdict(asyncio.Future)  # type: Dict[bytes, asyncio.Future[HtlcLog]]
+        self.pending_sent_htlcs = defaultdict(asyncio.Queue)  # type: Dict[bytes, asyncio.Future[HtlcLog]]
+
         self.pending_htlcs = defaultdict(set) # type: Dict[bytes, set]
+        self.htlc_routes = defaultdict(list)
 
         self.swap_manager = SwapManager(wallet=self.wallet, lnworker=self)
         # detect inflight payments
@@ -930,7 +932,7 @@ class LNWallet(LNWorker):
 
         return chan, funding_tx
 
-    def pay(self, invoice: str, *, amount_msat: int = None, attempts: int = 1) -> Tuple[bool, List[PaymentAttemptLog]]:
+    def pay(self, invoice: str, *, amount_msat: int = None, attempts: int = 1) -> Tuple[bool, List[HtlcLog]]:
         """
         Can be called from other threads
         """
@@ -945,13 +947,11 @@ class LNWallet(LNWorker):
 
     @log_exceptions
     async def _pay(
-            self,
-            invoice: str,
-            *,
+            self, invoice: str, *,
             amount_msat: int = None,
             attempts: int = 1,
-            full_path: LNPaymentPath = None,
-    ) -> Tuple[bool, List[PaymentAttemptLog]]:
+            full_path: LNPaymentPath = None) -> Tuple[bool, List[HtlcLog]]:
+
         lnaddr = self._check_invoice(invoice, amount_msat=amount_msat)
         payment_hash = lnaddr.paymenthash
         key = payment_hash.hex()
@@ -967,84 +967,89 @@ class LNWallet(LNWorker):
         self.logs[key] = log = []
         success = False
         reason = ''
-        for i in range(attempts):
-            try:
+        amount_to_pay = lnaddr.get_amount_msat()
+        amount_inflight = 0 # what we sent in htlcs
+
+        self.set_invoice_status(key, PR_INFLIGHT)
+        util.trigger_callback('invoice_status', self.wallet, key)
+        while True:
+            amount_to_send = amount_to_pay - amount_inflight
+            if amount_to_send > 0:
+                # 1. create a set of routes for remaining amount.
                 # note: path-finding runs in a separate thread so that we don't block the asyncio loop
                 # graph updates might occur during the computation
-                self.set_invoice_status(key, PR_INFLIGHT)
+                try:
+                    routes = await run_in_thread(partial(self.create_routes_from_invoice, amount_to_send, lnaddr, full_path=full_path))
+                except NoPathFound:
+                    # catch this exception because we still want to return the htlc log
+                    reason = 'No path found'
+                    break
+                # 2. send htlcs
+                for route, amount_msat in routes:
+                    await self.pay_to_route(route, amount_msat, lnaddr)
+                    amount_inflight += amount_msat
                 util.trigger_callback('invoice_status', self.wallet, key)
-                route = await run_in_thread(partial(self._create_route_from_invoice, lnaddr, full_path=full_path))
-                payment_attempt_log = await self._pay_to_route(route, lnaddr)
-            except Exception as e:
-                log.append(PaymentAttemptLog(success=False, exception=e))
-                reason = str(e)
+            # 3. await a queue
+            htlc_log = await self.pending_sent_htlcs[payment_hash].get()
+            amount_inflight -= htlc_log.amount_msat
+            log.append(htlc_log)
+            if htlc_log.success:
+                success = True
                 break
-            log.append(payment_attempt_log)
-            success = payment_attempt_log.success
-            if success:
+            # htlc failed
+            # if we get a tmp channel failure, it might work to split the amount and try more routes
+            # if we get a channel update, we might retry the same route and amount
+            if len(log) >= attempts:
+                reason = 'Giving up after %d attempts'%len(log)
                 break
-        else:
-            reason = _('Failed after {} attempts').format(attempts)
-        self.set_invoice_status(key, PR_PAID if success else PR_UNPAID)
-        util.trigger_callback('invoice_status', self.wallet, key)
+            if htlc_log.sender_idx is not None:
+                # apply channel update here
+                should_continue = self.handle_error_code_from_failed_htlc(htlc_log)
+                if not should_continue:
+                    break
+            else:
+                # probably got "update_fail_malformed_htlc". well... who to penalise now?
+                reason = 'sender idx missing'
+                break
+
+        # MPP: should we await all the inflight htlcs, or have another state?
         if success:
+            self.set_invoice_status(key, PR_PAID)
             util.trigger_callback('payment_succeeded', self.wallet, key)
         else:
+            self.set_invoice_status(key, PR_UNPAID)
             util.trigger_callback('payment_failed', self.wallet, key, reason)
+        util.trigger_callback('invoice_status', self.wallet, key)
         return success, log
 
-    async def _pay_to_route(self, route: LNPaymentRoute, lnaddr: LnAddr) -> PaymentAttemptLog:
+    async def pay_to_route(self, route: LNPaymentRoute, amount_msat:int, lnaddr: LnAddr):
+        # send a single htlc
         short_channel_id = route[0].short_channel_id
         chan = self.get_channel_by_short_id(short_channel_id)
         peer = self._peers.get(route[0].node_id)
+        payment_hash = lnaddr.paymenthash
         if not peer:
             raise Exception('Dropped peer')
         await peer.initialized
         htlc = peer.pay(
             route=route,
             chan=chan,
-            amount_msat=lnaddr.get_amount_msat(),
-            payment_hash=lnaddr.paymenthash,
+            amount_msat=amount_msat,
+            payment_hash=payment_hash,
             min_final_cltv_expiry=lnaddr.get_min_final_cltv_expiry(),
             payment_secret=lnaddr.payment_secret)
+        self.htlc_routes[(payment_hash, short_channel_id, htlc.htlc_id)] = route
         util.trigger_callback('htlc_added', chan, htlc, SENT)
-        payment_attempt = await self.await_payment(lnaddr.paymenthash)
-        if payment_attempt.success:
-            failure_log = None
-        else:
-            if payment_attempt.error_bytes:
-                # TODO "decode_onion_error" might raise, catch and maybe blacklist/penalise someone?
-                failure_msg, sender_idx = chan.decode_onion_error(payment_attempt.error_bytes, route, htlc.htlc_id)
-                is_blacklisted = self.handle_error_code_from_failed_htlc(failure_msg, sender_idx, route, peer)
-                if is_blacklisted:
-                    # blacklist channel after reporter node
-                    # TODO this should depend on the error (even more granularity)
-                    # also, we need finer blacklisting (directed edges; nodes)
-                    try:
-                        short_chan_id = route[sender_idx + 1].short_channel_id
-                    except IndexError:
-                        self.logger.info("payment destination reported error")
-                    else:
-                        self.logger.info(f'blacklisting channel {short_chan_id}')
-                        self.network.channel_blacklist.add(short_chan_id)
-            else:
-                # probably got "update_fail_malformed_htlc". well... who to penalise now?
-                assert payment_attempt.failure_message is not None
-                sender_idx = None
-                failure_msg = payment_attempt.failure_message
-                is_blacklisted = False
-            failure_log = PaymentAttemptFailureDetails(sender_idx=sender_idx,
-                                                       failure_msg=failure_msg,
-                                                       is_blacklisted=is_blacklisted)
-        return PaymentAttemptLog(route=route,
-                                 success=payment_attempt.success,
-                                 preimage=payment_attempt.preimage,
-                                 failure_details=failure_log)
-
-    def handle_error_code_from_failed_htlc(self, failure_msg, sender_idx, route, peer):
+
+    def handle_error_code_from_failed_htlc(self, htlc_log):
+        route = htlc_log.route
+        sender_idx = htlc_log.sender_idx
+        failure_msg = htlc_log.failure_msg
         code, data = failure_msg.code, failure_msg.data
         self.logger.info(f"UPDATE_FAIL_HTLC {repr(code)} {data}")
         self.logger.info(f"error reported by {bh2u(route[sender_idx].node_id)}")
+        if code == OnionFailureCode.MPP_TIMEOUT:
+            return False
         # handle some specific error codes
         failure_codes = {
             OnionFailureCode.TEMPORARY_CHANNEL_FAILURE: 0,
@@ -1067,7 +1072,10 @@ class LNWallet(LNWorker):
             short_channel_id = ShortChannelID(payload['short_channel_id'])
             if r == UpdateStatus.GOOD:
                 self.logger.info(f"applied channel update to {short_channel_id}")
-                peer.maybe_save_remote_update(payload)
+                # TODO: test this
+                for chan in self.channels.values():
+                    if chan.short_channel_id == short_channel_id:
+                        chan.set_remote_update(payload['raw'])
             elif r == UpdateStatus.ORPHANED:
                 # maybe it is a private channel (and data in invoice was outdated)
                 self.logger.info(f"Could not find {short_channel_id}. maybe update is for private channel?")
@@ -1082,7 +1090,23 @@ class LNWallet(LNWorker):
                 blacklist = True
         else:
             blacklist = True
-        return blacklist
+        # blacklist channel after reporter node
+        # TODO this should depend on the error (even more granularity)
+        # also, we need finer blacklisting (directed edges; nodes)
+        if blacklist and sender_idx:
+            try:
+                short_chan_id = route[sender_idx + 1].short_channel_id
+            except IndexError:
+                self.logger.info("payment destination reported error")
+                short_chan_id = None
+            else:
+                # TODO: for MPP we need to save the amount for which
+                # we saw temporary channel failure
+                self.logger.info(f'blacklisting channel {short_chan_id}')
+                self.network.channel_blacklist.add(short_chan_id)
+                return True
+        return False
+
 
     @classmethod
     def _decode_channel_update_msg(cls, chan_upd_msg: bytes) -> Optional[Dict[str, Any]]:
@@ -1123,9 +1147,13 @@ class LNWallet(LNWorker):
         return addr
 
     @profiler
-    def _create_route_from_invoice(self, decoded_invoice: 'LnAddr',
-                                   *, full_path: LNPaymentPath = None) -> LNPaymentRoute:
-        amount_msat = decoded_invoice.get_amount_msat()
+    def create_routes_from_invoice(
+            self,
+            amount_msat: int,
+            decoded_invoice: 'LnAddr',
+            *, full_path: LNPaymentPath = None) -> LNPaymentRoute:
+        # TODO: return multiples routes if we know that a single one will not work
+        # initially, try with less htlcs
         invoice_pubkey = decoded_invoice.pubkey.serialize()
         # use 'r' field from invoice
         route = None  # type: Optional[LNPaymentRoute]
@@ -1211,7 +1239,8 @@ class LNWallet(LNWorker):
         # add features from invoice
         invoice_features = decoded_invoice.get_tag('9') or 0
         route[-1].node_features |= invoice_features
-        return route
+        # return a list of routes
+        return [(route, amount_msat)]
 
     def add_request(self, amount_sat, message, expiry) -> str:
         coro = self._add_request_coro(amount_sat, message, expiry)
@@ -1297,7 +1326,8 @@ class LNWallet(LNWorker):
         expired = time.time() - first_timestamp > MPP_EXPIRY
         if total >= expected_msat and not expired:
             # status must be persisted
-            self.payment_received(htlc.payment_hash)
+            self.set_payment_status(htlc.payment_hash, PR_PAID)
+            util.trigger_callback('request_status', self.wallet, htlc.payment_hash.hex(), PR_PAID)
             return True, None
         if expired:
             return None, True
@@ -1326,12 +1356,6 @@ class LNWallet(LNWorker):
         if status in SAVED_PR_STATUS:
             self.set_payment_status(bfh(key), status)
 
-    async def await_payment(self, payment_hash: bytes) -> BarePaymentAttemptLog:
-        # note side-effect: Future is created and added here (defaultdict):
-        payment_attempt = await self.pending_payments[payment_hash]
-        self.pending_payments.pop(payment_hash)
-        return payment_attempt
-
     def set_payment_status(self, payment_hash: bytes, status):
         info = self.get_payment_info(payment_hash)
         if info is None:
@@ -1340,48 +1364,52 @@ class LNWallet(LNWorker):
         info = info._replace(status=status)
         self.save_payment_info(info)
 
-    def payment_failed(
+    def htlc_fulfilled(self, chan, payment_hash: bytes, htlc_id:int, amount_msat:int):
+        route = self.htlc_routes.get((payment_hash, chan.short_channel_id, htlc_id))
+        htlc_log = HtlcLog(
+            success=True,
+            route=route,
+            amount_msat=amount_msat)
+        q = self.pending_sent_htlcs[payment_hash]
+        q.put_nowait(htlc_log)
+        util.trigger_callback('htlc_fulfilled', payment_hash, chan.channel_id)
+
+    def htlc_failed(
             self,
-            chan: Channel,
+            chan,
             payment_hash: bytes,
+            htlc_id: int,
+            amount_msat:int,
             error_bytes: Optional[bytes],
-            failure_message: Optional['OnionRoutingFailureMessage'],
-    ):
-        self.set_payment_status(payment_hash, PR_UNPAID)
-        f = self.pending_payments.get(payment_hash)
-        if f and not f.cancelled():
-            payment_attempt = BarePaymentAttemptLog(
-                success=False,
-                error_bytes=error_bytes,
-                failure_message=failure_message)
-            f.set_result(payment_attempt)
-        else:
-            chan.logger.info('received unexpected payment_failed, probably from previous session')
-            key = payment_hash.hex()
-            util.trigger_callback('invoice_status', self.wallet, key)
-            util.trigger_callback('payment_failed', self.wallet, key, '')
-        util.trigger_callback('ln_payment_failed', payment_hash, chan.channel_id)
-
-    def payment_sent(self, chan, payment_hash: bytes):
-        self.set_payment_status(payment_hash, PR_PAID)
-        preimage = self.get_preimage(payment_hash)
-        f = self.pending_payments.get(payment_hash)
-        if f and not f.cancelled():
-            payment_attempt = BarePaymentAttemptLog(
-                success=True,
-                preimage=preimage)
-            f.set_result(payment_attempt)
+            failure_message: Optional['OnionRoutingFailureMessage']):
+
+        route = self.htlc_routes.get((payment_hash, chan.short_channel_id, htlc_id))
+        if error_bytes and route:
+            self.logger.info(f" {(error_bytes, route, htlc_id)}")
+            # TODO "decode_onion_error" might raise, catch and maybe blacklist/penalise someone?
+            try:
+                failure_message, sender_idx = chan.decode_onion_error(error_bytes, route, htlc_id)
+            except Exception as e:
+                sender_idx = None
+                failure_message = OnionRoutingFailureMessage(-1, str(e))
         else:
-            chan.logger.info('received unexpected payment_sent, probably from previous session')
-            key = payment_hash.hex()
-            util.trigger_callback('invoice_status', self.wallet, key)
-            util.trigger_callback('payment_succeeded', self.wallet, key)
-        util.trigger_callback('ln_payment_completed', payment_hash, chan.channel_id)
+            # probably got "update_fail_malformed_htlc". well... who to penalise now?
+            assert failure_message is not None
+            sender_idx = None
+
+        htlc_log = HtlcLog(
+            success=False,
+            route=route,
+            amount_msat=amount_msat,
+            error_bytes=error_bytes,
+            failure_msg=failure_message,
+            sender_idx=sender_idx)
+
+        q = self.pending_sent_htlcs[payment_hash]
+        q.put_nowait(htlc_log)
+        util.trigger_callback('htlc_failed', payment_hash, chan.channel_id)
+
 
-    def payment_received(self, payment_hash: bytes):
-        self.set_payment_status(payment_hash, PR_PAID)
-        util.trigger_callback('request_status', self.wallet, payment_hash.hex(), PR_PAID)
-        #util.trigger_callback('ln_payment_completed', payment_hash, chan.channel_id)
 
     async def _calc_routing_hints_for_invoice(self, amount_msat: Optional[int]):
         """calculate routing hints (BOLT-11 'r' field)"""

electrum/tests/test_lnpeer.py

@@ -133,6 +133,8 @@ class MockLNWallet(Logger, NetworkRetryManager[LNPeerAddr]):
         self.enable_htlc_settle = asyncio.Event()
         self.enable_htlc_settle.set()
         self.pending_htlcs = defaultdict(set)
+        self.pending_sent_htlcs = defaultdict(asyncio.Queue)
+        self.htlc_routes = defaultdict(list)
 
     def get_invoice_status(self, key):
         pass
@@ -169,15 +171,13 @@ class MockLNWallet(Logger, NetworkRetryManager[LNPeerAddr]):
     set_payment_status = LNWallet.set_payment_status
     get_payment_status = LNWallet.get_payment_status
     htlc_received = LNWallet.htlc_received
-    await_payment = LNWallet.await_payment
-    payment_received = LNWallet.payment_received
-    payment_sent = LNWallet.payment_sent
-    payment_failed = LNWallet.payment_failed
+    htlc_fulfilled = LNWallet.htlc_fulfilled
+    htlc_failed = LNWallet.htlc_failed
     save_preimage = LNWallet.save_preimage
     get_preimage = LNWallet.get_preimage
-    _create_route_from_invoice = LNWallet._create_route_from_invoice
+    create_routes_from_invoice = LNWallet.create_routes_from_invoice
     _check_invoice = staticmethod(LNWallet._check_invoice)
-    _pay_to_route = LNWallet._pay_to_route
+    pay_to_route = LNWallet.pay_to_route
     _pay = LNWallet._pay
     force_close_channel = LNWallet.force_close_channel
     try_force_closing = LNWallet.try_force_closing
@@ -490,27 +490,27 @@ class TestPeer(ElectrumTestCase):
             lnaddr1 = lndecode(pay_req1, expected_hrp=constants.net.SEGWIT_HRP)
             # alice sends htlc BUT NOT COMMITMENT_SIGNED
             p1.maybe_send_commitment = lambda x: None
+            route1, amount_msat1 = w1.create_routes_from_invoice(lnaddr2.get_amount_msat(), decoded_invoice=lnaddr2)[0]
             p1.pay(
-                route=w1._create_route_from_invoice(decoded_invoice=lnaddr2),
+                route=route1,
                 chan=alice_channel,
                 amount_msat=lnaddr2.get_amount_msat(),
                 payment_hash=lnaddr2.paymenthash,
                 min_final_cltv_expiry=lnaddr2.get_min_final_cltv_expiry(),
                 payment_secret=lnaddr2.payment_secret,
             )
-            w1.pending_payments[lnaddr2.paymenthash] = asyncio.Future()
             p1.maybe_send_commitment = _maybe_send_commitment1
             # bob sends htlc BUT NOT COMMITMENT_SIGNED
             p2.maybe_send_commitment = lambda x: None
+            route2, amount_msat2 = w2.create_routes_from_invoice(lnaddr1.get_amount_msat(), decoded_invoice=lnaddr1)[0]
             p2.pay(
-                route=w2._create_route_from_invoice(decoded_invoice=lnaddr1),
+                route=route2,
                 chan=bob_channel,
                 amount_msat=lnaddr1.get_amount_msat(),
                 payment_hash=lnaddr1.paymenthash,
                 min_final_cltv_expiry=lnaddr1.get_min_final_cltv_expiry(),
                 payment_secret=lnaddr1.payment_secret,
             )
-            w2.pending_payments[lnaddr1.paymenthash] = asyncio.Future()
             p2.maybe_send_commitment = _maybe_send_commitment2
             # sleep a bit so that they both receive msgs sent so far
             await asyncio.sleep(0.1)
@@ -518,10 +518,10 @@ class TestPeer(ElectrumTestCase):
             p1.maybe_send_commitment(alice_channel)
             p2.maybe_send_commitment(bob_channel)
 
-            payment_attempt1 = await w1.await_payment(lnaddr2.paymenthash)
-            assert payment_attempt1.success
-            payment_attempt2 = await w2.await_payment(lnaddr1.paymenthash)
-            assert payment_attempt2.success
+            htlc_log1 = await w1.pending_sent_htlcs[lnaddr2.paymenthash].get()
+            assert htlc_log1.success
+            htlc_log2 = await w2.pending_sent_htlcs[lnaddr1.paymenthash].get()
+            assert htlc_log2.success
             raise PaymentDone()
 
         async def f():
@@ -594,21 +594,20 @@ class TestPeer(ElectrumTestCase):
             with self.subTest(msg="bad path: edges do not chain together"):
                 path = [PathEdge(node_id=graph.w_c.node_keypair.pubkey, short_channel_id=graph.chan_ab.short_channel_id),
                         PathEdge(node_id=graph.w_d.node_keypair.pubkey, short_channel_id=graph.chan_bd.short_channel_id)]
-                result, log = await graph.w_a._pay(pay_req, full_path=path)
-                self.assertFalse(result)
-                self.assertTrue(isinstance(log[0].exception, LNPathInconsistent))
+                with self.assertRaises(LNPathInconsistent):
+                    await graph.w_a._pay(pay_req, full_path=path)
             with self.subTest(msg="bad path: last node id differs from invoice pubkey"):
                 path = [PathEdge(node_id=graph.w_b.node_keypair.pubkey, short_channel_id=graph.chan_ab.short_channel_id)]
-                result, log = await graph.w_a._pay(pay_req, full_path=path)
-                self.assertFalse(result)
-                self.assertTrue(isinstance(log[0].exception, LNPathInconsistent))
+                with self.assertRaises(LNPathInconsistent):
+                    await graph.w_a._pay(pay_req, full_path=path)
             with self.subTest(msg="good path"):
                 path = [PathEdge(node_id=graph.w_b.node_keypair.pubkey, short_channel_id=graph.chan_ab.short_channel_id),
                         PathEdge(node_id=graph.w_d.node_keypair.pubkey, short_channel_id=graph.chan_bd.short_channel_id)]
                 result, log = await graph.w_a._pay(pay_req, full_path=path)
                 self.assertTrue(result)
-                self.assertEqual([edge.short_channel_id for edge in path],
-                                 [edge.short_channel_id for edge in log[0].route])
+                self.assertEqual(
+                    [edge.short_channel_id for edge in path],
+                    [edge.short_channel_id for edge in log[0].route])
             raise PaymentDone()
         async def f():
             async with TaskGroup() as group:
@@ -630,7 +629,7 @@ class TestPeer(ElectrumTestCase):
         async def pay(pay_req):
             result, log = await graph.w_a._pay(pay_req)
             self.assertFalse(result)
-            self.assertEqual(OnionFailureCode.TEMPORARY_NODE_FAILURE, log[0].failure_details.failure_msg.code)
+            self.assertEqual(OnionFailureCode.TEMPORARY_NODE_FAILURE, log[0].failure_msg.code)
             raise PaymentDone()
         async def f():
             async with TaskGroup() as group:
@@ -658,7 +657,7 @@ class TestPeer(ElectrumTestCase):
             await asyncio.wait_for(p1.initialized, 1)
             await asyncio.wait_for(p2.initialized, 1)
             # alice sends htlc
-            route = w1._create_route_from_invoice(decoded_invoice=lnaddr)
+            route, amount_msat = w1.create_routes_from_invoice(lnaddr.get_amount_msat(), decoded_invoice=lnaddr)[0]
             htlc = p1.pay(route=route,
                           chan=alice_channel,
                           amount_msat=lnaddr.get_amount_msat(),
@@ -752,21 +751,22 @@ class TestPeer(ElectrumTestCase):
         p1, p2, w1, w2, q1, q2 = self.prepare_peers(alice_channel, bob_channel)
         pay_req = run(self.prepare_invoice(w2))
 
-        addr = w1._check_invoice(pay_req)
-        route = w1._create_route_from_invoice(decoded_invoice=addr)
+        lnaddr = w1._check_invoice(pay_req)
+        route, amount_msat = w1.create_routes_from_invoice(lnaddr.get_amount_msat(), decoded_invoice=lnaddr)[0]
+        assert amount_msat == lnaddr.get_amount_msat()
 
         run(w1.force_close_channel(alice_channel.channel_id))
         # check if a tx (commitment transaction) was broadcasted:
         assert q1.qsize() == 1
 
         with self.assertRaises(NoPathFound) as e:
-            w1._create_route_from_invoice(decoded_invoice=addr)
+            w1.create_routes_from_invoice(lnaddr.get_amount_msat(), decoded_invoice=lnaddr)
 
         peer = w1.peers[route[0].node_id]
         # AssertionError is ok since we shouldn't use old routes, and the
         # route finding should fail when channel is closed
         async def f():
-            await asyncio.gather(w1._pay_to_route(route, addr), p1._message_loop(), p2._message_loop(), p1.htlc_switch(), p2.htlc_switch())
+            await asyncio.gather(w1.pay_to_route(route, amount_msat, lnaddr), p1._message_loop(), p2._message_loop(), p1.htlc_switch(), p2.htlc_switch())
         with self.assertRaises(PaymentFailure):
             run(f())