From 530a446172ac244a7a96b277edfeae9fffa65c1d Mon Sep 17 00:00:00 2001
From: SomberNight <somber.night@protonmail.com>
Date: Fri, 22 May 2020 17:11:53 +0200
Subject: [PATCH] follow-up prev: don't reuse funding tx change address for
 static_remotekey

see comment in code
---
 electrum/lnpeer.py   | 29 +++++++++++++++++++++++++++--
 electrum/lnworker.py |  2 +-
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/electrum/lnpeer.py b/electrum/lnpeer.py
index 1d3bd8536..fc634e7a9 100644
--- a/electrum/lnpeer.py
+++ b/electrum/lnpeer.py
@@ -517,9 +517,34 @@ class Peer(Logger):
         )
         return local_config
 
+    def temporarily_reserve_funding_tx_change_address(func):
+        # During the channel open flow, if we initiated, we might have used a change address
+        # of ours in the funding tx. The funding tx is not part of the wallet history
+        # at that point yet, but we should already consider this change address as 'used'.
+        async def wrapper(self: 'Peer', *args, **kwargs):
+            funding_tx = kwargs['funding_tx']  # type: PartialTransaction
+            wallet = self.lnworker.wallet
+            change_addresses = [txout.address for txout in funding_tx.outputs()
+                                if wallet.is_change(txout.address)]
+            for addr in change_addresses:
+                wallet.set_reserved_state_of_address(addr, reserved=True)
+            try:
+                return await func(self, *args, **kwargs)
+            finally:
+                for addr in change_addresses:
+                    self.lnworker.wallet.set_reserved_state_of_address(addr, reserved=False)
+        return wrapper
+
     @log_exceptions
-    async def channel_establishment_flow(self, password: Optional[str], funding_tx: 'PartialTransaction', funding_sat: int,
-                                         push_msat: int, temp_channel_id: bytes) -> Tuple[Channel, 'PartialTransaction']:
+    @temporarily_reserve_funding_tx_change_address
+    async def channel_establishment_flow(
+            self, *,
+            password: Optional[str],
+            funding_tx: 'PartialTransaction',
+            funding_sat: int,
+            push_msat: int,
+            temp_channel_id: bytes
+    ) -> Tuple[Channel, 'PartialTransaction']:
         await asyncio.wait_for(self.initialized, LN_P2P_NETWORK_TIMEOUT)
         feerate = self.lnworker.current_feerate_per_kw()
         local_config = self.make_local_config(funding_sat, push_msat, LOCAL)
diff --git a/electrum/lnworker.py b/electrum/lnworker.py
index ace7e41ff..93fcf1a2a 100644
--- a/electrum/lnworker.py
+++ b/electrum/lnworker.py
@@ -749,7 +749,7 @@ class LNWallet(LNWorker):
         # will raise if init fails
         await asyncio.wait_for(peer.initialized, LN_P2P_NETWORK_TIMEOUT)
         chan, funding_tx = await peer.channel_establishment_flow(
-            password,
+            password=password,
             funding_tx=funding_tx,
             funding_sat=funding_sat,
             push_msat=push_sat * 1000,