opening: save the correct commitment tx when we are the fundee.

We were saving *our* commitment tx, not theirs.

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

openingd/opening.c

@@ -460,7 +460,7 @@ static u8 *fundee_channel(struct state *state,
 	struct basepoints theirs;
 	struct pubkey their_funding_pubkey;
 	secp256k1_ecdsa_signature theirsig, sig;
-	struct bitcoin_tx *tx;
+	struct bitcoin_tx *their_commit, *our_commit;
 	struct sha256_double chain_hash;
 	u8 *msg;
 	const u8 *wscript;
@@ -609,16 +609,16 @@ static u8 *fundee_channel(struct state *state,
 	 *
 	 * The recipient MUST fail the channel if `signature` is incorrect.
 	 */
-	tx = initial_channel_tx(state, &wscript, state->channel,
+	their_commit = initial_channel_tx(state, &wscript, state->channel,
 					  &state->next_per_commit[LOCAL], LOCAL);
 
-	if (!check_tx_sig(tx, 0, NULL, wscript, &their_funding_pubkey,
+	if (!check_tx_sig(their_commit, 0, NULL, wscript, &their_funding_pubkey,
 			  &theirsig)) {
 		peer_failed(PEER_FD, &state->cs, &state->channel_id,
 			    "Bad signature %s on tx %s using key %s",
 			    type_to_string(trc, secp256k1_ecdsa_signature,
 					   &theirsig),
-			    type_to_string(trc, struct bitcoin_tx, tx),
+			    type_to_string(trc, struct bitcoin_tx, their_commit),
 			    type_to_string(trc, struct pubkey,
 					   &their_funding_pubkey));
 	}
@@ -642,9 +642,9 @@ static u8 *fundee_channel(struct state *state,
 	 * commitment transaction, so they can broadcast it knowing they can
 	 * redeem their funds if they need to.
 	 */
-	tx = initial_channel_tx(state, &wscript, state->channel,
+	our_commit = initial_channel_tx(state, &wscript, state->channel,
 					&state->next_per_commit[REMOTE], REMOTE);
-	sign_tx_input(tx, 0, NULL, wscript,
+	sign_tx_input(our_commit, 0, NULL, wscript,
 		      &state->our_secrets.funding_privkey,
 		      our_funding_pubkey, &sig);
 
@@ -654,7 +654,7 @@ static u8 *fundee_channel(struct state *state,
 
 	return towire_opening_fundee_reply(state,
 					   state->remoteconf,
-					   tx,
+					   their_commit,
 					   &theirsig,
 					   &state->cs,
 					   &theirs.revocation,

tests/test_lightningd.py

@@ -447,6 +447,48 @@ class LightningDTests(BaseLightningDTests):
         bitcoind.rpc.generate(6)
         l2.daemon.wait_for_log('onchaind complete, forgetting peer')
 
+    def test_onchain_first_commit(self):
+        """Onchain handling where funder immediately drops to chain"""
+
+        # HTLC 1->2, 1 fails just after funding.
+        disconnects = ['+WIRE_FUNDING_LOCKED', 'permfail']
+        l1 = self.node_factory.get_node(disconnect=disconnects)
+        l2 = self.node_factory.get_node()
+
+        l1.rpc.connect('localhost', l2.info['port'], l2.info['id'])
+
+        # Like fundchannel, but we'll probably fail before CHANNELD_NORMAL.
+        addr = l1.rpc.newaddr()['address']
+
+        txid = l1.bitcoin.rpc.sendtoaddress(addr, 10**6 / 10**8 + 0.01)
+        tx = l1.bitcoin.rpc.getrawtransaction(txid)
+
+        l1.rpc.addfunds(tx)
+        l1.rpc.fundchannel(l2.info['id'], 10**6)
+        l1.daemon.wait_for_log('sendrawtx exit 0')
+
+        l1.bitcoin.rpc.generate(1)
+
+        # l1 will drop to chain.
+        l1.daemon.wait_for_log('permfail')
+        l1.daemon.wait_for_log('sendrawtx exit 0')
+        l1.bitcoin.rpc.generate(1)
+        l1.daemon.wait_for_log('-> ONCHAIND_OUR_UNILATERAL')
+        l2.daemon.wait_for_log('-> ONCHAIND_THEIR_UNILATERAL')
+
+        # 6 later, l1 should collect its to-self payment.
+        bitcoind.rpc.generate(6)
+        l1.daemon.wait_for_log('Broadcasting OUR_DELAYED_RETURN_TO_WALLET .* to resolve OUR_UNILATERAL/DELAYED_OUTPUT_TO_US')
+        l1.daemon.wait_for_log('sendrawtx exit 0')
+
+        # 94 later, l2 is done.
+        bitcoind.rpc.generate(94)
+        l2.daemon.wait_for_log('onchaind complete, forgetting peer')
+
+        # Now, 100 blocks and l1 should be done.
+        bitcoind.rpc.generate(6)
+        l1.daemon.wait_for_log('onchaind complete, forgetting peer')
+
     def test_onchain_dust_out(self):
         """Onchain handling of outgoing dust htlcs (they should fail)"""
         # HTLC 1->2, 1 fails after it's irrevocably committed