onchain: Add message to notify about their_unilater/to-us outputs

This is the only case in which we don't respend to a simple keyindex'd
pubkey, so we need to handle this for future spends.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

lightningd/peer_control.c

@@ -1276,6 +1276,14 @@ static void handle_irrevocably_resolved(struct peer *peer, const u8 *msg)
 	free_peer(peer, "onchaind complete, forgetting peer");
 }
 
+/**
+ * onchain_add_utxo -- onchaind is telling us about a UTXO we own
+ */
+static void onchain_add_utxo(struct peer *peer, const u8 *msg)
+{
+	/* FIXME(cdecker) Implement */
+}
+
 static unsigned int onchain_msg(struct subd *sd, const u8 *msg, const int *fds)
 {
 	enum onchain_wire_type t = fromwire_peektype(msg);
@@ -1309,6 +1317,10 @@ static unsigned int onchain_msg(struct subd *sd, const u8 *msg, const int *fds)
 		handle_irrevocably_resolved(sd->peer, msg);
 		break;
 
+	case WIRE_ONCHAIN_ADD_UTXO:
+		onchain_add_utxo(sd->peer, msg);
+		break;
+
 	/* We send these, not receive them */
 	case WIRE_ONCHAIN_INIT:
 	case WIRE_ONCHAIN_SPENT:

onchaind/onchain.c

@@ -1887,6 +1887,13 @@ static void handle_their_unilateral(const struct bitcoin_tx *tx,
 						 OUTPUT_TO_US, NULL, NULL, NULL);
 			ignore_output(out);
 			script[LOCAL] = NULL;
+
+			/* Tell the master that it will want to add
+			 * this UTXO to its outputs */
+			wire_sync_write(REQ_FD, towire_onchain_add_utxo(
+						    tmpctx, txid, i,
+						    remote_per_commitment_point,
+						    tx->output[i].amount));
 			continue;
 		}
 		if (script[REMOTE]

onchaind/onchain_wire.csv

@@ -82,3 +82,10 @@ onchain_htlc_timeout,,htlc,struct htlc_stub
 
 # onchaind->master: this peer can be forgotten
 onchain_all_irrevocably_resolved,5011
+
+# onchaind->master: hey, I identified a UTXO you'll want to track
+onchain_add_utxo,5012
+onchain_add_utxo,,prev_out_tx,struct bitcoin_txid
+onchain_add_utxo,,prev_out_index,u32
+onchain_add_utxo,,per_commit_point,struct pubkey
+onchain_add_utxo,,value,u64