lightningd: track balance in way which matches channeld.

Currently it's fairly ad-hoc, but we need to tell it to channeld when
it restarts, so we define it as the non-HTLC balance.

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

lightningd/peer_control.c

@@ -587,11 +587,11 @@ static void json_getpeers(struct command *cmd,
 		if (p->scid)
 			json_add_short_channel_id(response, "channel", p->scid);
 		if (p->balance) {
-			json_add_u64(response, "msatoshi_to_us",
-				     p->balance[LOCAL]);
-			json_add_u64(response, "msatoshi_to_them",
-				     p->balance[REMOTE]);
+			json_add_u64(response, "msatoshi_to_us", *p->balance);
+			json_add_u64(response, "msatoshi_total",
+				     p->funding_satoshi * 1000);
 		}
+
 		if (leveltok) {
 			info.response = response;
 			json_array_start(response, "log");
@@ -982,9 +982,11 @@ static void peer_start_channeld(struct peer *peer, enum peer_state oldstate,
 	log_debug(peer->log, "Waiting for HSM file descriptor");
 
 	/* Now we can consider balance set. */
-	peer->balance = tal_arr(peer, u64, NUM_SIDES);
-	peer->balance[peer->funder] = peer->funding_satoshi * 1000 - peer->push_msat;
-	peer->balance[!peer->funder] = peer->push_msat;
+	peer->balance = tal(peer, u64);
+	if (peer->funder == LOCAL)
+		*peer->balance = peer->funding_satoshi * 1000 - peer->push_msat;
+	else
+		*peer->balance = peer->push_msat;
 
 	peer_set_condition(peer, oldstate, GETTING_HSMFD);
 

lightningd/peer_control.h

@@ -69,7 +69,7 @@ struct peer {
 	u16 funding_outnum;
 	u64 funding_satoshi, push_msat;
 
-	/* Channel balance (LOCAL and REMOTE); if we have one. */
+	/* Amount going to us, not counting unfinished HTLCs; if we have one. */
 	u64 *balance;
 
 	/* Keys for channel. */

lightningd/peer_htlcs.c

@@ -175,8 +175,8 @@ static void fulfill_htlc(struct htlc_in *hin, const struct preimage *preimage)
 {
 	u8 *msg;
 
-	hin->key.peer->balance[LOCAL] += hin->msatoshi;
-	hin->key.peer->balance[REMOTE] -= hin->msatoshi;
+	hin->preimage = tal_dup(hin, struct preimage, preimage);
+	htlc_in_check(hin, __func__);
 
 	/* FIXME: fail the peer if it doesn't tell us that htlc fulfill is
 	 * committed before deadline.
@@ -628,10 +628,6 @@ static bool peer_fulfilled_our_htlc(struct peer *peer,
 
 	/* FIXME: Save to db */
 
-	/* They fulfilled our HTLC.  Credit them, forward immediately. */
-	peer->balance[REMOTE] += hout->msatoshi;
-	peer->balance[LOCAL] -= hout->msatoshi;
-
 	if (hout->in)
 		fulfill_htlc(hout->in, &fulfilled->payment_preimage);
 	else
@@ -665,16 +661,30 @@ static bool peer_failed_our_htlc(struct peer *peer,
 static void remove_htlc_in(struct peer *peer, struct htlc_in *hin)
 {
 	htlc_in_check(hin, __func__);
-	log_debug(peer->log, "Removing in HTLC %"PRIu64" state %s",
-		  hin->key.id, htlc_state_name(hin->hstate));
+	assert(hin->failuremsg || hin->preimage);
+
+	log_debug(peer->log, "Removing in HTLC %"PRIu64" state %s %s",
+		  hin->key.id, htlc_state_name(hin->hstate),
+		  hin->failuremsg ? "FAILED" : "FULFILLED");
+
+	/* If we fulfilled their HTLC, credit us. */
+	if (hin->preimage) {
+		log_debug(peer->log, "Balance %"PRIu64" -> %"PRIu64,
+			  *peer->balance,
+			  *peer->balance + hin->msatoshi);
+		*peer->balance += hin->msatoshi;
+	}
+
 	tal_free(hin);
 }
 
 static void remove_htlc_out(struct peer *peer, struct htlc_out *hout)
 {
 	htlc_out_check(hout, __func__);
-	log_debug(peer->log, "Removing out HTLC %"PRIu64" state %s",
-		  hout->key.id, htlc_state_name(hout->hstate));
+	assert(hout->failuremsg || hout->preimage);
+	log_debug(peer->log, "Removing out HTLC %"PRIu64" state %s %s",
+		  hout->key.id, htlc_state_name(hout->hstate),
+		  hout->failuremsg ? "FAILED" : "FULFILLED");
 
 	/* If it's failed, now we can forward since it's completely locked-in */
 	if (hout->failuremsg) {
@@ -687,6 +697,9 @@ static void remove_htlc_out(struct peer *peer, struct htlc_out *hout)
 		} else {
 			payment_failed(peer->ld, hout);
 		}
+	} else {
+		/* We paid for this HTLC, so deduct balance. */
+		*peer->balance -= hout->msatoshi;
 	}
 
 	tal_free(hout);

tests/test_lightningd.py

@@ -204,6 +204,18 @@ class LightningDTests(BaseLightningDTests):
         assert p1['owner'] == 'lightningd_gossip'
         assert p2['owner'] == 'lightningd_gossip'
 
+    def test_balance(self):
+        l1,l2 = self.connect()
+
+        self.fund_channel(l1, l2, 10**6)
+
+        p1 = l1.rpc.getpeer(l2.info['id'], 'info')
+        p2 = l2.rpc.getpeer(l1.info['id'], 'info')
+        assert p1['msatoshi_to_us'] == 10**6 * 1000
+        assert p1['msatoshi_total'] == 10**6 * 1000
+        assert p2['msatoshi_to_us'] == 0
+        assert p2['msatoshi_total'] == 10**6 * 1000
+
     def test_sendpay(self):
         l1,l2 = self.connect()
 
@@ -246,10 +258,27 @@ class LightningDTests(BaseLightningDTests):
         self.assertRaises(ValueError, l1.rpc.sendpay, to_json([rs]), rhash)
         assert l2.rpc.listinvoice('testpayment2')[0]['complete'] == False
 
+        # FIXME: test paying via another node, should fail to pay twice.
+        p1 = l1.rpc.getpeer(l2.info['id'], 'info')
+        p2 = l2.rpc.getpeer(l1.info['id'], 'info')
+        assert p1['msatoshi_to_us'] == 10**6 * 1000
+        assert p1['msatoshi_total'] == 10**6 * 1000
+        assert p2['msatoshi_to_us'] == 0
+        assert p2['msatoshi_total'] == 10**6 * 1000
+
         # This works.
         l1.rpc.sendpay(to_json([routestep]), rhash)
         assert l2.rpc.listinvoice('testpayment2')[0]['complete'] == True
-        
+
+        # Balances should reflect it.
+        time.sleep(1)        
+        p1 = l1.rpc.getpeer(l2.info['id'], 'info')
+        p2 = l2.rpc.getpeer(l1.info['id'], 'info')
+        assert p1['msatoshi_to_us'] == 10**6 * 1000 - amt
+        assert p1['msatoshi_total'] == 10**6 * 1000
+        assert p2['msatoshi_to_us'] == amt
+        assert p2['msatoshi_total'] == 10**6 * 1000
+
         # Repeat will "succeed", but won't actually send anything (duplicate)
         assert not l1.daemon.is_in_log('... succeeded')
         l1.rpc.sendpay(to_json([routestep]), rhash)
@@ -263,7 +292,6 @@ class LightningDTests(BaseLightningDTests):
         l1.rpc.sendpay(to_json([routestep]), rhash)
         assert l2.rpc.listinvoice('testpayment3')[0]['complete'] == True
 
-        # FIXME: test paying via another node, should fail to pay twice.
 
     def test_gossip_jsonrpc(self):
         l1,l2 = self.connect()