lnchannel: save htlc preimages as soon as possible but horribly hacky

will properly clean this up...

electrum/lnchannel.py

@@ -28,6 +28,7 @@ import binascii
 import json
 from enum import Enum, auto
 from typing import Optional, Dict, List, Tuple, NamedTuple, Set, Callable, Iterable, Sequence
+import time
 
 from . import ecc
 from .util import bfh, PrintError, bh2u
@@ -120,10 +121,9 @@ class Channel(PrintError):
             return super().diagnostic_name()
 
     def __init__(self, state, *, sweep_address=None, name=None,
-                 payment_completed: Optional[Callable[['Channel', Direction, UpdateAddHtlc, bytes], None]] = None):
+                 payment_completed: Optional[Callable[['Channel', Direction, UpdateAddHtlc], None]] = None):
-        self.preimages = {}
         if not payment_completed:
-            payment_completed = lambda this, x, y, z: None
+            payment_completed = lambda this, x, y: None
         self.sweep_address = sweep_address
         self.payment_completed = payment_completed
         assert 'local_state' not in state
@@ -438,10 +438,9 @@ class Channel(PrintError):
         received = self.hm.received_in_ctn(self.config[LOCAL].ctn)
         sent = self.hm.sent_in_ctn(self.config[LOCAL].ctn)
         for htlc in received:
-            self.payment_completed(self, RECEIVED, htlc, None)
+            self.payment_completed(self, RECEIVED, htlc)
         for htlc in sent:
-            preimage = self.preimages.pop(htlc.htlc_id)
+            self.payment_completed(self, SENT, htlc)
-            self.payment_completed(self, SENT, htlc, preimage)
         received_this_batch = htlcsum(received)
         sent_this_batch = htlcsum(sent)
 
@@ -625,8 +624,12 @@ class Channel(PrintError):
         assert htlc.payment_hash == sha256(preimage)
         assert htlc_id not in log['settles']
         self.hm.recv_settle(htlc_id)
-        self.preimages[htlc_id] = preimage
+        try:
-        # we don't save the preimage because we don't need to forward it anyway
+            self.save_preimage(htlc.payment_hash, preimage, timestamp=int(time.time()))
+        except AttributeError as e:
+            # save_preimage is not defined in the unit tests... this is ugly as hell. FIXME
+            import traceback
+            traceback.print_exc()
 
     def fail_htlc(self, htlc_id):
         self.print_error("fail_htlc")

electrum/lnpeer.py

@@ -379,6 +379,7 @@ class Peer(PrintError):
                        payment_completed=self.lnworker.payment_completed)
         chan.lnwatcher = self.lnwatcher
         chan.get_preimage = self.lnworker.get_preimage  # FIXME hack.
+        chan.save_preimage = self.lnworker.save_preimage  # FIXME hack.
         sig_64, _ = chan.sign_next_commitment()
         self.send_message("funding_created",
             temporary_channel_id=temp_channel_id,
@@ -472,6 +473,7 @@ class Peer(PrintError):
                        payment_completed=self.lnworker.payment_completed)
         chan.lnwatcher = self.lnwatcher
         chan.get_preimage = self.lnworker.get_preimage  # FIXME hack.
+        chan.save_preimage = self.lnworker.save_preimage  # FIXME hack.
         remote_sig = funding_created['signature']
         chan.receive_new_commitment(remote_sig, [])
         sig_64, _ = chan.sign_next_commitment()

electrum/lnworker.py

@@ -79,7 +79,8 @@ class LNWorker(PrintError):
         self.channels = {}  # type: Dict[bytes, Channel]
         for x in wallet.storage.get("channels", []):
             c = Channel(x, sweep_address=self.sweep_address, payment_completed=self.payment_completed)
-            c.get_preimage = self.get_preimage
+            c.get_preimage = self.get_preimage  # FIXME hack.
+            c.save_preimage = self.save_preimage  # FIXME hack.
             self.channels[c.channel_id] = c
             c.set_remote_commitment()
             c.set_local_commitment(c.current_commitment(LOCAL))
@@ -126,11 +127,10 @@ class LNWorker(PrintError):
             self.print_error('saved lightning gossip timestamp')
 
     def payment_completed(self, chan: Channel, direction: Direction,
-                          htlc: UpdateAddHtlc, preimage: Optional[bytes]):
+                          htlc: UpdateAddHtlc):
         chan_id = chan.channel_id
-        preimage = preimage if preimage else self.get_preimage(htlc.payment_hash)
+        preimage = self.get_preimage(htlc.payment_hash)
         timestamp = int(time.time())
-        self.save_preimage(htlc.payment_hash, preimage, timestamp=timestamp)
         self.network.trigger_callback('ln_payment_completed', timestamp, direction, htlc, preimage, chan_id)
 
     def get_invoice_status(self, payment_hash):