channel_reestablish: assume that DLP is enabled, because we require it

electrum/lnpeer.py

@@ -728,28 +728,21 @@ class Peer(Logger):
         oldest_unrevoked_remote_ctn = chan.get_oldest_unrevoked_ctn(REMOTE)
         latest_remote_ctn = chan.get_latest_ctn(REMOTE)
         next_remote_ctn = chan.get_next_ctn(REMOTE)
+        assert self.localfeatures & LnLocalFeatures.OPTION_DATA_LOSS_PROTECT_OPT
         # send message
-        dlp_enabled = self.localfeatures & LnLocalFeatures.OPTION_DATA_LOSS_PROTECT_OPT
-        if dlp_enabled:
-            if oldest_unrevoked_remote_ctn == 0:
-                last_rev_secret = 0
-            else:
-                last_rev_index = oldest_unrevoked_remote_ctn - 1
-                last_rev_secret = chan.revocation_store.retrieve_secret(RevocationStore.START_INDEX - last_rev_index)
-            latest_secret, latest_point = chan.get_secret_and_point(LOCAL, latest_local_ctn)
-            self.send_message(
-                "channel_reestablish",
-                channel_id=chan_id,
-                next_local_commitment_number=next_local_ctn,
-                next_remote_revocation_number=oldest_unrevoked_remote_ctn,
-                your_last_per_commitment_secret=last_rev_secret,
-                my_current_per_commitment_point=latest_point)
+        if oldest_unrevoked_remote_ctn == 0:
+            last_rev_secret = 0
         else:
-            self.send_message(
-                "channel_reestablish",
-                channel_id=chan_id,
-                next_local_commitment_number=next_local_ctn,
-                next_remote_revocation_number=oldest_unrevoked_remote_ctn)
+            last_rev_index = oldest_unrevoked_remote_ctn - 1
+            last_rev_secret = chan.revocation_store.retrieve_secret(RevocationStore.START_INDEX - last_rev_index)
+        latest_secret, latest_point = chan.get_secret_and_point(LOCAL, latest_local_ctn)
+        self.send_message(
+            "channel_reestablish",
+            channel_id=chan_id,
+            next_local_commitment_number=next_local_ctn,
+            next_remote_revocation_number=oldest_unrevoked_remote_ctn,
+            your_last_per_commitment_secret=last_rev_secret,
+            my_current_per_commitment_point=latest_point)
         self.logger.info(f'channel_reestablish: sent channel_reestablish with '
                          f'(next_local_ctn={next_local_ctn}, '
                          f'oldest_unrevoked_remote_ctn={oldest_unrevoked_remote_ctn})')
@@ -823,8 +816,7 @@ class Peer(Logger):
         # option_data_loss_protect
         def are_datalossprotect_fields_valid() -> bool:
             if their_local_pcp is None or their_claim_of_our_last_per_commitment_secret is None:
-                # if DLP was enabled, absence of fields is not OK
-                return not dlp_enabled
+                return False
             if their_oldest_unrevoked_remote_ctn > 0:
                 our_pcs, __ = chan.get_secret_and_point(LOCAL, their_oldest_unrevoked_remote_ctn - 1)
             else:
@@ -845,14 +837,12 @@ class Peer(Logger):
 
         if not are_datalossprotect_fields_valid():
             raise RemoteMisbehaving("channel_reestablish: data loss protect fields invalid")
-        else:
-            if dlp_enabled and should_close_they_are_ahead:
-                self.logger.warning(f"channel_reestablish: remote is ahead of us! luckily DLP is enabled. remote PCP: {bh2u(their_local_pcp)}")
-                # data_loss_protect_remote_pcp is used in lnsweep
-                chan.set_data_loss_protect_remote_pcp(their_next_local_ctn - 1, their_local_pcp)
-                self.lnworker.save_channel(chan)
+
         if should_close_they_are_ahead:
-            self.logger.warning(f"channel_reestablish: remote is ahead of us! They should force-close.")
+            self.logger.warning(f"channel_reestablish: remote is ahead of us! They should force-close. Remote PCP: {bh2u(their_local_pcp)}")
+            # data_loss_protect_remote_pcp is used in lnsweep
+            chan.set_data_loss_protect_remote_pcp(their_next_local_ctn - 1, their_local_pcp)
+            self.lnworker.save_channel(chan)
             chan.peer_state = peer_states.BAD
             return
         elif should_close_we_are_ahead:

electrum/tests/test_lnpeer.py

@@ -85,6 +85,7 @@ class MockLNWallet:
         self.logs = defaultdict(list)
         self.wallet = MockWallet()
         self.localfeatures = LnLocalFeatures(0)
+        self.localfeatures |= LnLocalFeatures.OPTION_DATA_LOSS_PROTECT_OPT
         self.pending_payments = defaultdict(asyncio.Future)
 
     def get_invoice_status(self, key):