funding: explicitly mark which side offered the anchor.

The channel funding code needs to know who offered the anchor, as they
are responsible for paying fees until the other side is able to.  This
is actually a hack, but at least now it's internal to funding and not
passed in at every funding_delta() call.

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

daemon/packets.c

@@ -448,8 +448,7 @@ Pkt *accept_pkt_htlc_add(const tal_t *ctx,
 	}
 
 	cur->cstate = copy_funding(cur, peer->cstate);
-	if (!funding_delta(peer->them.offer_anchor == CMD_OPEN_WITH_ANCHOR,
-			   peer->anchor.satoshis,
+	if (!funding_delta(peer->anchor.satoshis,
 			   0, cur->htlc->msatoshis,
 			   &cur->cstate->b, &cur->cstate->a)) {
 		err = pkt_err(ctx, "Cannot afford %"PRIu64" milli-satoshis",
@@ -510,8 +509,7 @@ Pkt *accept_pkt_htlc_fail(const tal_t *ctx, struct peer *peer, const Pkt *pkt)
 
 	/* Removing it should not fail: we regain HTLC amount */
 	cur->cstate = copy_funding(cur, peer->cstate);
-	if (!funding_delta(peer->us.offer_anchor == CMD_OPEN_WITH_ANCHOR,
-			   peer->anchor.satoshis,
+	if (!funding_delta(peer->anchor.satoshis,
 			   0, -cur->htlc->msatoshis,
 			   &cur->cstate->a, &cur->cstate->b)) {
 		fatal("Unexpected failure fulfilling HTLC of %"PRIu64
@@ -560,8 +558,7 @@ Pkt *accept_pkt_htlc_fulfill(const tal_t *ctx,
 
 	/* Removing it should not fail: they gain HTLC amount */
 	cur->cstate = copy_funding(cur, peer->cstate);
-	if (!funding_delta(peer->us.offer_anchor == CMD_OPEN_WITH_ANCHOR,
-			   peer->anchor.satoshis,
+	if (!funding_delta(peer->anchor.satoshis,
 			   -cur->htlc->msatoshis,
 			   -cur->htlc->msatoshis,
 			   &cur->cstate->a, &cur->cstate->b)) {

daemon/peer.c

@@ -834,9 +834,7 @@ bool peer_create_close_tx(struct peer *peer, u64 fee_satoshis)
 	
 	/* We don't need a deep copy here, just fee levels. */
 	cstate = *peer->cstate;
-	if (!adjust_fee(peer->us.offer_anchor == CMD_OPEN_WITH_ANCHOR,
-			peer->anchor.satoshis,
-			fee_satoshis,
+	if (!adjust_fee(peer->anchor.satoshis, fee_satoshis,
 			&cstate.a, &cstate.b))
 		return false;
 
@@ -1322,9 +1320,7 @@ static void check_htlc_expiry(struct peer *peer, void *unused)
 		cstate = copy_funding(peer, peer->cstate);
 
 		/* This should never fail! */
-		if (!funding_delta(peer->them.offer_anchor
-				   == CMD_OPEN_WITH_ANCHOR,
-				   peer->anchor.satoshis,
+		if (!funding_delta(peer->anchor.satoshis,
 				   0,
 				   -htlc->msatoshis,
 				   &cstate->b, &cstate->a)) {
@@ -1371,8 +1367,7 @@ static void do_newhtlc(struct peer *peer, struct newhtlc *newhtlc)
 	/* Can we even offer this much?  We check now, just before we
 	 * execute. */
 	cstate = copy_funding(newhtlc, peer->cstate);
-	if (!funding_delta(peer->us.offer_anchor == CMD_OPEN_WITH_ANCHOR,
-			   peer->anchor.satoshis,
+	if (!funding_delta(peer->anchor.satoshis,
 			   0, newhtlc->htlc->msatoshis,
 			   &cstate->a, &cstate->b)) {
 		command_fail(newhtlc->jsoncmd,
@@ -1508,8 +1503,7 @@ static void do_fullfill(struct peer *peer,
 
 	cstate = copy_funding(fulfillhtlc, peer->cstate);
 	/* This should never fail! */
-	if (!funding_delta(peer->them.offer_anchor == CMD_OPEN_WITH_ANCHOR,
-			   peer->anchor.satoshis,
+	if (!funding_delta(peer->anchor.satoshis,
 			   -htlc->msatoshis,
 			   -htlc->msatoshis,
 			   &cstate->b, &cstate->a)) {
@@ -1599,8 +1593,7 @@ static void do_failhtlc(struct peer *peer,
 	cstate = copy_funding(failhtlc, peer->cstate);
 
 	/* This should never fail! */
-	if (!funding_delta(peer->them.offer_anchor == CMD_OPEN_WITH_ANCHOR,
-			   peer->anchor.satoshis,
+	if (!funding_delta(peer->anchor.satoshis,
 			   0,
 			   -htlc->msatoshis,
 			   &cstate->b, &cstate->a)) {

funding.c

@@ -45,8 +45,7 @@ static uint64_t htlcs_total(const struct channel_htlc *htlcs)
 	return total;
 }
 
-static bool change_funding(bool a_is_funder,
-			   uint64_t anchor_satoshis,
+static bool change_funding(uint64_t anchor_satoshis,
 			   int64_t delta_a_msat,
 			   int64_t htlc_msat,
 			   uint64_t a, uint64_t b, uint64_t fee,
@@ -59,6 +58,7 @@ static bool change_funding(bool a_is_funder,
 
 	assert(a + b + htlcs_total(a_side->htlcs) + htlcs_total(b_side->htlcs)
 	       == anchor_satoshis * 1000);
+	assert(a_side->offered_anchor != b_side->offered_anchor);
 
 	/* B gets whatever A gives. */
 	delta_b_msat = -delta_a_msat;
@@ -76,7 +76,7 @@ static bool change_funding(bool a_is_funder,
 	b += delta_b_msat;
 
 	/* Take off fee from both parties if possible. */
-	if (a_is_funder)
+	if (a_side->offered_anchor)
 		got_fees = subtract_fees(&a, &b, &a_fee, &b_fee,
 					 delta_b_msat < 0, fee);
 	else
@@ -94,8 +94,7 @@ static bool change_funding(bool a_is_funder,
 	return true;
 }
 
-bool funding_delta(bool a_is_funder,
-		   uint64_t anchor_satoshis,
+bool funding_delta(uint64_t anchor_satoshis,
 		   int64_t delta_a_msat,
 		   int64_t htlc_msat,
 		   struct channel_oneside *a_side,
@@ -109,7 +108,7 @@ bool funding_delta(bool a_is_funder,
 	b = b_side->pay_msat + b_side->fee_msat;
 	fee = a_side->fee_msat + b_side->fee_msat;
 
-	return change_funding(a_is_funder, anchor_satoshis,
+	return change_funding(anchor_satoshis,
 			      delta_a_msat, htlc_msat,
 			      a, b, fee,
 			      a_side, b_side);
@@ -134,19 +133,19 @@ struct channel_state *initial_funding(const tal_t *ctx,
 	/* Initially, all goes back to funder. */
 	state->a.pay_msat = anchor_satoshis * 1000 - fee * 1000;
 	state->a.fee_msat = fee * 1000;
+	state->a.offered_anchor = true;
+	state->b.offered_anchor = false;
 
 	/* If B (not A) is funder, invert. */
 	if (!am_funder)
 		invert_cstate(state);
 
 	/* Make sure it checks out. */
-	assert(funding_delta(am_funder, anchor_satoshis, 0, 0,
-			     &state->a, &state->b));
+	assert(funding_delta(anchor_satoshis, 0, 0, &state->a, &state->b));
 	return state;
 }
 
-bool adjust_fee(bool a_is_funder,
-		uint64_t anchor_satoshis,
+bool adjust_fee(uint64_t anchor_satoshis,
 		uint64_t fee_satoshis,
 		struct channel_oneside *a_side,
 		struct channel_oneside *b_side)
@@ -157,7 +156,7 @@ bool adjust_fee(bool a_is_funder,
 	b = b_side->pay_msat + b_side->fee_msat;
 
 	/* No HTLC or delta, just fee recalculate. */
-	return change_funding(a_is_funder, anchor_satoshis,
+	return change_funding(anchor_satoshis,
 			      0, 0, a, b, fee_satoshis * 1000,
 			      a_side, b_side);
 }

funding.h

@@ -15,6 +15,8 @@ struct channel_htlc {
 struct channel_oneside {
 	/* Payment and fee is in millisatoshi. */
 	uint32_t pay_msat, fee_msat;
+	/* Did we offer the anchor? */
+	bool offered_anchor;
 	/* Use tal_count to get the number */
 	struct channel_htlc *htlcs;
 };
@@ -47,15 +49,13 @@ struct channel_state *copy_funding(const tal_t *ctx,
 
 /**
  * funding_delta: With this change, what's the new state?
- * @a_is_funder: is A paying for the anchor?
  * @anchor_satoshis: The anchor amount.
  * @delta_a: How many millisatoshi A changes (-ve => A pay B, +ve => B pays A)
  * @htlc: Millisatoshi A is putting into a HTLC (-ve if htlc is cancelled)
  * @a_side: channel a's state to update.
  * @b_side: channel b's state to update.
  */
-bool funding_delta(bool a_is_funder,
-		   uint64_t anchor_satoshis,
+bool funding_delta(uint64_t anchor_satoshis,
 		   int64_t delta_a_msat,
 		   int64_t htlc_msat,
 		   struct channel_oneside *a_side,
@@ -63,14 +63,12 @@ bool funding_delta(bool a_is_funder,
 
 /**
  * adjust_fee: Change fee.
- * @a_is_funder: is A paying for the anchor?
  * @anchor_satoshis: The anchor amount.
  * @fee_satoshis: The new fee amount.
  * @a_side: channel a's state to update.
  * @b_side: channel b's state to update.
  */
-bool adjust_fee(bool a_is_funder,
-		uint64_t anchor_satoshis,
+bool adjust_fee(uint64_t anchor_satoshis,
 		uint64_t fee_satoshis,
 		struct channel_oneside *a_side,
 		struct channel_oneside *b_side);