lightningd: correctly store our own channel_reserve_satoshis

openingd calculates our reserve based on the channel amount (even if
we're funding, to keep the calculation in one place), but it wasn't
reporting it back to the master daemon.  We initialized it to 0 so that
valgrind wouldn't get upset, as it's part of a structure we send over
the wire.

Have openingd report back, and also initialize it to an impossible value
as extra assurance.  And remove a stray (harmless but weird) semicolon.

Reported-by: Gálli Zoltán
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/opening_control.c

@@ -314,7 +314,8 @@ static void opening_funder_finished(struct subd *openingd, const u8 *resp,
 					   &fc->uc->minimum_depth,
 					   &channel_info.remote_fundingkey,
 					   &expected_txid,
-					   &feerate)) {
+					   &feerate,
+					   &fc->uc->our_config.channel_reserve_satoshis)) {
 		log_broken(fc->uc->log,
 			   "bad OPENING_FUNDER_REPLY %s",
 			   tal_hex(resp, resp));
@@ -502,7 +503,8 @@ static void opening_fundee_finished(struct subd *openingd,
 					   &push_msat,
 					   &channel_flags,
 					   &feerate,
-					   &funding_signed)) {
+					   &funding_signed,
+					   &uc->our_config.channel_reserve_satoshis)) {
 		log_broken(uc->log, "bad OPENING_FUNDEE_REPLY %s",
 			   tal_hex(reply, reply));
 		tal_free(uc);
@@ -674,8 +676,8 @@ static void channel_config(struct lightningd *ld,
 	 ours->max_accepted_htlcs = 483;
 
 	 /* This is filled in by lightning_openingd, for consistency. */
-	 ours->channel_reserve_satoshis = 0;
+	 ours->channel_reserve_satoshis = -1;
-};
+}
 
 /* Peer has spontaneously exited from connectd due to open msg.  Return
  * NULL if we took over, otherwise hand back to connectd with this

openingd/opening.c

@@ -544,7 +544,8 @@ static u8 *funder_channel(struct state *state,
 					   minimum_depth,
 					   &their_funding_pubkey,
 					   &state->funding_txid,
-					   state->feerate_per_kw);
+					   state->feerate_per_kw,
+					   state->localconf.channel_reserve_satoshis);
 }
 
 /* This is handed the message the peer sent which caused gossip to stop:
@@ -819,7 +820,8 @@ static u8 *fundee_channel(struct state *state,
 					   state->push_msat,
 					   channel_flags,
 					   state->feerate_per_kw,
-					   msg);
+					   msg,
+					   state->localconf.channel_reserve_satoshis);
 }
 
 #ifndef TESTING

openingd/opening_wire.csv

@@ -44,6 +44,7 @@ opening_funder_reply,,minimum_depth,u32
 opening_funder_reply,,remote_fundingkey,struct pubkey
 opening_funder_reply,,funding_txid,struct bitcoin_txid
 opening_funder_reply,,feerate_per_kw,u32
+opening_funder_reply,,our_channel_reserve_satoshis,u64
 
 # This means they offer the open (contains their offer packet)
 opening_fundee,6003
@@ -74,3 +75,4 @@ opening_fundee_reply,,feerate_per_kw,u32
 # The (encrypted) funding signed message: send this and we're committed.
 opening_fundee_reply,,msglen,u16
 opening_fundee_reply,,funding_signed_msg,msglen*u8
+opening_fundee_reply,,our_channel_reserve_satoshis,u64

tests/test_lightningd.py

@@ -7,7 +7,6 @@ from utils import wait_for
 import copy
 import json
 import logging
-import pytest
 import queue
 import os
 import random
@@ -5114,7 +5113,6 @@ class LightningDTests(BaseLightningDTests):
         # fundee will also forget and disconnect from peer.
         assert len(l2.rpc.listpeers(l1.info['id'])['peers']) == 0
 
-    @pytest.mark.xfail(strict=True)
     def test_reserve_enforcement(self):
         """Channeld should disallow you spending into your reserve"""
         l1, l2 = self.connect(may_reconnect=True)
@@ -5125,6 +5123,9 @@ class LightningDTests(BaseLightningDTests):
 
         l2.stop()
 
+        # They should both aim for 1%.
+        assert l2.db_query('SELECT channel_reserve_satoshis FROM channel_configs') == [{'channel_reserve_satoshis': 10**6 // 100}, {'channel_reserve_satoshis': 10**6 // 100}]
+
         # Edit db to reduce reserve to 0 so it will try to violate it.
         l2.db_query('UPDATE channel_configs SET channel_reserve_satoshis=0',
                     use_copy=False)