common/utxo: make commitment_point optional in close_info.

We don't rotate key for option_static_remotekey, so we don't need
this point for such channels.

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

common/utxo.c

@@ -20,7 +20,9 @@ void towire_utxo(u8 **pptr, const struct utxo *utxo)
 	if (is_unilateral_close) {
 		towire_u64(pptr, utxo->close_info->channel_id);
 		towire_node_id(pptr, &utxo->close_info->peer_id);
-		towire_pubkey(pptr, &utxo->close_info->commitment_point);
+		towire_bool(pptr, utxo->close_info->commitment_point != NULL);
+		if (utxo->close_info->commitment_point)
+			towire_pubkey(pptr, utxo->close_info->commitment_point);
 	}
 }
 
@@ -42,7 +44,13 @@ struct utxo *fromwire_utxo(const tal_t *ctx, const u8 **ptr, size_t *max)
 		utxo->close_info = tal(utxo, struct unilateral_close_info);
 		utxo->close_info->channel_id = fromwire_u64(ptr, max);
 		fromwire_node_id(ptr, max, &utxo->close_info->peer_id);
-		fromwire_pubkey(ptr, max, &utxo->close_info->commitment_point);
+		if (fromwire_bool(ptr, max)) {
+			utxo->close_info->commitment_point = tal(utxo,
+								 struct pubkey);
+			fromwire_pubkey(ptr, max,
+					utxo->close_info->commitment_point);
+		} else
+			utxo->close_info->commitment_point = NULL;
 	} else {
 		utxo->close_info = NULL;
 	}

common/utxo.h

@@ -17,7 +17,8 @@ struct ext_key;
 struct unilateral_close_info {
 	u64 channel_id;
 	struct node_id peer_id;
-	struct pubkey commitment_point;
+	/* NULL if this is an option_static_remotekey commitment */
+	struct pubkey *commitment_point;
 };
 
 struct utxo {

hsmd/hsmd.c

@@ -1386,7 +1386,7 @@ static void hsm_unilateral_close_privkey(struct privkey *dst,
 	derive_basepoints(&channel_seed, NULL, &basepoints, &secrets, NULL);
 
 	if (!derive_simple_privkey(&secrets.payment_basepoint_secret,
-				   &basepoints.payment, &info->commitment_point,
+				   &basepoints.payment, info->commitment_point,
 				   dst)) {
 		status_failed(STATUS_FAIL_INTERNAL_ERROR,
 			      "Deriving unilateral_close_privkey");

onchaind/onchain_wire.csv

@@ -91,7 +91,7 @@ msgtype,onchain_all_irrevocably_resolved,5011
 msgtype,onchain_add_utxo,5012
 msgdata,onchain_add_utxo,prev_out_tx,bitcoin_txid,
 msgdata,onchain_add_utxo,prev_out_index,u32,
-msgdata,onchain_add_utxo,per_commit_point,pubkey,
+msgdata,onchain_add_utxo,per_commit_point,?pubkey,
 msgdata,onchain_add_utxo,value,amount_sat,
 msgdata,onchain_add_utxo,blockheight,u32,
 msgdata,onchain_add_utxo,len,u16,

wallet/test/run-wallet.c

@@ -784,7 +784,7 @@ static bool test_wallet_outputs(struct lightningd *ld, const tal_t *ctx)
 	u.close_info = tal(w, struct unilateral_close_info);
 	u.close_info->channel_id = 42;
 	u.close_info->peer_id = id;
-	u.close_info->commitment_point = pk;
+	u.close_info->commitment_point = &pk;
 	CHECK_MSG(wallet_add_utxo(w, &u, p2sh_wpkh),
 		  "wallet_add_utxo with close_info");
 
@@ -796,7 +796,7 @@ static bool test_wallet_outputs(struct lightningd *ld, const tal_t *ctx)
 
 	u = *utxos[1];
 	CHECK(u.close_info->channel_id == 42 &&
-	      pubkey_eq(&u.close_info->commitment_point, &pk) &&
+	      pubkey_eq(u.close_info->commitment_point, &pk) &&
 	      node_id_eq(&u.close_info->peer_id, &id));
 	/* Now un-reserve them for the tests below */
 	tal_free(utxos);
@@ -826,6 +826,29 @@ static bool test_wallet_outputs(struct lightningd *ld, const tal_t *ctx)
 					      output_state_spent),
 		  "could not change output state ignoring oldstate");
 
+	/* Attempt to save an UTXO with close_info set, no commitment_point */
+	memset(&u.txid, 2, sizeof(u.txid));
+	u.amount = AMOUNT_SAT(5);
+	u.close_info = tal(w, struct unilateral_close_info);
+	u.close_info->channel_id = 42;
+	u.close_info->peer_id = id;
+	u.close_info->commitment_point = NULL;
+	CHECK_MSG(wallet_add_utxo(w, &u, p2sh_wpkh),
+		  "wallet_add_utxo with close_info no commitment_point");
+
+	/* Now select it */
+	utxos = wallet_select_coins(w, w, AMOUNT_SAT(5), 0, 21,
+				    0 /* no confirmations required */,
+				    &fee_estimate, &change_satoshis);
+	CHECK(utxos && tal_count(utxos) == 2);
+
+	u = *utxos[1];
+	CHECK(u.close_info->channel_id == 42 &&
+	      u.close_info->commitment_point == NULL &&
+	      node_id_eq(&u.close_info->peer_id, &id));
+	/* Now un-reserve them */
+	tal_free(utxos);
+
 	db_commit_transaction(w->db);
 	return true;
 }

wallet/wallet.c

@@ -111,7 +111,10 @@ bool wallet_add_utxo(struct wallet *w, struct utxo *utxo,
 	if (utxo->close_info) {
 		db_bind_u64(stmt, 6, utxo->close_info->channel_id);
 		db_bind_node_id(stmt, 7, &utxo->close_info->peer_id);
-		db_bind_pubkey(stmt, 8, &utxo->close_info->commitment_point);
+		if (utxo->close_info->commitment_point)
+			db_bind_pubkey(stmt, 8, utxo->close_info->commitment_point);
+		else
+			db_bind_null(stmt, 8);
 	} else {
 		db_bind_null(stmt, 6);
 		db_bind_null(stmt, 7);
@@ -155,7 +158,13 @@ static struct utxo *wallet_stmt2output(const tal_t *ctx, struct db_stmt *stmt)
 		utxo->close_info = tal(utxo, struct unilateral_close_info);
 		utxo->close_info->channel_id = db_column_u64(stmt, 6);
 		db_column_node_id(stmt, 7, &utxo->close_info->peer_id);
-		db_column_pubkey(stmt, 8, &utxo->close_info->commitment_point);
+		if (!db_column_is_null(stmt, 8)) {
+			utxo->close_info->commitment_point
+				= tal(utxo->close_info, struct pubkey);
+			db_column_pubkey(stmt, 8,
+					 utxo->close_info->commitment_point);
+		} else
+			utxo->close_info->commitment_point = NULL;
 	} else {
 		utxo->close_info = NULL;
 	}