lightningd: use CPFP on peer's commitment tx if we can't broadcast our own

channeld/channeld.c

@@ -1169,9 +1169,7 @@ static u8 *sending_commitsig_msg(const tal_t *ctx,
 				 struct penalty_base *pbase,
 				 const struct fee_states *fee_states,
 				 const struct height_states *blockheight_states,
-				 const struct htlc **changed_htlcs,
-				 const struct bitcoin_signature *commit_sig,
-				 const struct bitcoin_signature *htlc_sigs)
+				 const struct htlc **changed_htlcs)
 {
 	struct changed_htlc *changed;
 	u8 *msg;
@@ -1181,8 +1179,7 @@ static u8 *sending_commitsig_msg(const tal_t *ctx,
 	changed = changed_htlc_arr(tmpctx, changed_htlcs);
 	msg = towire_channeld_sending_commitsig(ctx, remote_commit_index,
 						pbase, fee_states,
-						blockheight_states, changed,
-						commit_sig, htlc_sigs);
+						blockheight_states, changed);
 	return msg;
 }
 
@@ -1504,14 +1501,17 @@ static bool want_blockheight_update(const struct peer *peer, u32 *height)
 	return true;
 }
 
-static u8 *send_commit_part(struct peer *peer,
-			     const struct bitcoin_outpoint *funding,
-			     struct amount_sat funding_sats,
-			     const struct htlc **changed_htlcs,
-			     bool notify_master,
-			     s64 splice_amnt,
-			     s64 remote_splice_amnt,
-			     u64 remote_index)
+/* Returns commitment_signed msg, sets @local_anchor */
+static u8 *send_commit_part(const tal_t *ctx,
+			    struct peer *peer,
+			    const struct bitcoin_outpoint *funding,
+			    struct amount_sat funding_sats,
+			    const struct htlc **changed_htlcs,
+			    bool notify_master,
+			    s64 splice_amnt,
+			    s64 remote_splice_amnt,
+			    u64 remote_index,
+			    struct local_anchor_info **anchor)
 {
 	u8 *msg;
 	struct bitcoin_signature commit_sig, *htlc_sigs;
@@ -1520,6 +1520,7 @@ static u8 *send_commit_part(struct peer *peer,
 	const struct htlc **htlc_map;
 	struct wally_tx_output *direct_outputs[NUM_SIDES];
 	struct penalty_base *pbase;
+	int local_anchor_outnum;
 	struct tlv_commitment_signed_tlvs *cs_tlv
 		= tlv_commitment_signed_tlvs_new(tmpctx);
 
@@ -1536,11 +1537,11 @@ static u8 *send_commit_part(struct peer *peer,
 		derive_channel_id(cs_tlv->splice_info, funding);
 	}
 
-	txs = channel_splice_txs(tmpctx, funding, funding_sats, &htlc_map,
-				 direct_outputs, &funding_wscript,
-				 peer->channel, &peer->remote_per_commit,
-				 remote_index, REMOTE,
-				 splice_amnt, remote_splice_amnt);
+	txs = channel_txs(tmpctx, funding, funding_sats, &htlc_map,
+			  direct_outputs, &funding_wscript,
+			  peer->channel, &peer->remote_per_commit,
+			  remote_index, REMOTE,
+			  splice_amnt, remote_splice_amnt, &local_anchor_outnum);
 	htlc_sigs =
 	    calc_commitsigs(tmpctx, peer, txs, funding_wscript, htlc_map,
 			    remote_index, &commit_sig);
@@ -1555,6 +1556,16 @@ static u8 *send_commit_part(struct peer *peer,
 	}  else
 		pbase = NULL;
 
+	if (local_anchor_outnum == -1) {
+		*anchor = NULL;
+	} else {
+		*anchor = tal(ctx, struct local_anchor_info);
+		bitcoin_txid(txs[0], &(*anchor)->anchor_point.txid);
+		(*anchor)->anchor_point.n = local_anchor_outnum;
+		(*anchor)->commitment_weight = bitcoin_tx_weight(txs[0]);
+		(*anchor)->commitment_fee = bitcoin_tx_compute_fee(txs[0]);
+	}
+
 	if (peer->dev_disable_commit) {
 		(*peer->dev_disable_commit)--;
 		if (*peer->dev_disable_commit == 0)
@@ -1568,9 +1579,7 @@ static u8 *send_commit_part(struct peer *peer,
 		msg = sending_commitsig_msg(NULL, remote_index, pbase,
 					    peer->channel->fee_states,
 					    peer->channel->blockheight_states,
-					    changed_htlcs,
-					    &commit_sig,
-					    htlc_sigs);
+					    changed_htlcs);
 		/* Message is empty; receiving it is the point. */
 		master_wait_sync_reply(tmpctx, peer, take(msg),
 				       WIRE_CHANNELD_SENDING_COMMITSIG_REPLY);
@@ -1579,7 +1588,7 @@ static u8 *send_commit_part(struct peer *peer,
 			     tal_count(htlc_sigs));
 	}
 
-	msg = towire_commitment_signed(NULL, &peer->channel_id,
+	msg = towire_commitment_signed(ctx, &peer->channel_id,
 				       &commit_sig.s,
 				       raw_sigs(tmpctx, htlc_sigs),
 				       cs_tlv);
@@ -1599,6 +1608,7 @@ static void send_commit(struct peer *peer)
 	u32 feerate_target;
 	u8 **msgs = tal_arr(tmpctx, u8*, 1);
 	u8 *msg;
+	struct local_anchor_info *local_anchor, *anchors_info;
 
 	if (peer->dev_disable_commit && !*peer->dev_disable_commit) {
 		peer->commit_timer = NULL;
@@ -1710,9 +1720,13 @@ static void send_commit(struct peer *peer)
 		return;
 	}
 
-	msgs[0] = send_commit_part(peer, &peer->channel->funding,
+	anchors_info = tal_arr(tmpctx, struct local_anchor_info, 0);
+	msgs[0] = send_commit_part(msgs, peer, &peer->channel->funding,
 				   peer->channel->funding_sats, changed_htlcs,
-				   true, 0, 0, peer->next_index[REMOTE]);
+				   true, 0, 0, peer->next_index[REMOTE],
+				   &local_anchor);
+	if (local_anchor)
+		tal_arr_expand(&anchors_info, *local_anchor);
 
 	/* Loop over current inflights
 	 * BOLT-0d8b701614b09c6ee4172b04da2203e73deec7e2 #2:
@@ -1730,15 +1744,23 @@ static void send_commit(struct peer *peer)
 					- peer->splice_state->inflights[i]->splice_amnt;
 
 		tal_arr_expand(&msgs,
-			       send_commit_part(peer,
+			       send_commit_part(msgs, peer,
 						&peer->splice_state->inflights[i]->outpoint,
 						peer->splice_state->inflights[i]->amnt,
 						changed_htlcs, false,
 						peer->splice_state->inflights[i]->splice_amnt,
 						remote_splice_amnt,
-						peer->next_index[REMOTE]));
+						peer->next_index[REMOTE],
+						&local_anchor));
+		if (local_anchor)
+			tal_arr_expand(&anchors_info, *local_anchor);
 	}
 
+	/* Now, tell master about the anchor on each of their commitments */
+	msg = towire_channeld_local_anchor_info(NULL, peer->next_index[REMOTE],
+						anchors_info);
+	wire_sync_write(MASTER_FD, take(msg));
+
 	peer->next_index[REMOTE]++;
 
 	for(u32 i = 0; i < tal_count(msgs); i++)
@@ -1972,6 +1994,7 @@ static struct commitsig *handle_peer_commit_sig(struct peer *peer,
 	struct amount_sat funding_sats;
 	struct channel_id active_id;
 	const struct commitsig **commitsigs;
+	int remote_anchor_outnum;
 
 	status_debug("handle_peer_commit_sig(splice: %d, remote_splice: %d)",
 		     (int)splice_amnt, (int)remote_splice_amnt);
@@ -2052,11 +2075,11 @@ static struct commitsig *handle_peer_commit_sig(struct peer *peer,
 		funding_sats = peer->channel->funding_sats;
 	}
 
-	txs = channel_splice_txs(tmpctx, &outpoint, funding_sats, &htlc_map,
-				 NULL, &funding_wscript, peer->channel,
-				 &peer->next_local_per_commit,
-				 peer->next_index[LOCAL], LOCAL, splice_amnt,
-				 remote_splice_amnt);
+	txs = channel_txs(tmpctx, &outpoint, funding_sats, &htlc_map,
+			  NULL, &funding_wscript, peer->channel,
+			  &peer->next_local_per_commit,
+			  peer->next_index[LOCAL], LOCAL, splice_amnt,
+			  remote_splice_amnt, &remote_anchor_outnum);
 
 	/* Set the commit_sig on the commitment tx psbt */
 	if (!psbt_input_set_signature(txs[0]->psbt, 0,
@@ -4387,6 +4410,7 @@ static void resend_commitment(struct peer *peer, struct changed_htlc *last)
 	size_t i;
 	u8 *msg;
 	u8 **msgs = tal_arr(tmpctx, u8*, 1);
+	struct local_anchor_info *local_anchor;
 
 	status_debug("Retransmitting commitment, feerate LOCAL=%u REMOTE=%u,"
 		     " blockheight LOCAL=%u REMOTE=%u",
@@ -4477,9 +4501,10 @@ static void resend_commitment(struct peer *peer, struct changed_htlc *last)
 		}
 	}
 
-	msgs[0] = send_commit_part(peer, &peer->channel->funding,
+	msgs[0] = send_commit_part(msgs, peer, &peer->channel->funding,
 				   peer->channel->funding_sats, NULL,
-				   false, 0, 0, peer->next_index[REMOTE] - 1);
+				   false, 0, 0, peer->next_index[REMOTE] - 1,
+				   &local_anchor);
 
 	/* Loop over current inflights
 	 * BOLT-0d8b701614b09c6ee4172b04da2203e73deec7e2 #2:
@@ -4497,13 +4522,14 @@ static void resend_commitment(struct peer *peer, struct changed_htlc *last)
 					- peer->splice_state->inflights[i]->splice_amnt;
 
 		tal_arr_expand(&msgs,
-			       send_commit_part(peer,
+			       send_commit_part(msgs, peer,
 						&peer->splice_state->inflights[i]->outpoint,
 						peer->splice_state->inflights[i]->amnt,
 						NULL, false,
 						peer->splice_state->inflights[i]->splice_amnt,
 						remote_splice_amnt,
-						peer->next_index[REMOTE] - 1));
+						peer->next_index[REMOTE] - 1,
+						&local_anchor));
 	}
 
 	for(i = 0; i < tal_count(msgs); i++)
@@ -5787,6 +5813,7 @@ static void req_in(struct peer *peer, const u8 *msg)
 	case WIRE_CHANNELD_UPDATE_INFLIGHT:
 	case WIRE_CHANNELD_GOT_INFLIGHT:
 	case WIRE_CHANNELD_SPLICE_STATE_ERROR:
+	case WIRE_CHANNELD_LOCAL_ANCHOR_INFO:
 		break;
 	}
 	master_badmsg(-1, msg);

channeld/channeld_wire.csv

@@ -128,6 +128,18 @@ msgdata,channeld_got_splice_locked,locked_txid,bitcoin_txid,
 
 #include <common/penalty_base.h>
 
+subtype,local_anchor_info
+subtypedata,local_anchor_info,commitment_weight,u32,
+subtypedata,local_anchor_info,commitment_fee,amount_sat,
+subtypedata,local_anchor_info,anchor_point,bitcoin_outpoint,
+
+# lightningd needs to track our anchor outputs on remote txs.
+# This includes splices, so there could be more than one!
+msgtype,channeld_local_anchor_info,1003
+msgdata,channeld_local_anchor_info,remote_commitnum,u64,
+msgdata,channeld_local_anchor_info,num_anchors,u16,
+msgdata,channeld_local_anchor_info,anchors,local_anchor_info,num_anchors
+
 # When we send a commitment_signed message, tell master.
 msgtype,channeld_sending_commitsig,1020
 msgdata,channeld_sending_commitsig,commitnum,u64,
@@ -137,9 +149,7 @@ msgdata,channeld_sending_commitsig,blockheight_states,height_states,
 # SENT_ADD_COMMIT, SENT_REMOVE_ACK_COMMIT, SENT_ADD_ACK_COMMIT, SENT_REMOVE_COMMIT
 msgdata,channeld_sending_commitsig,num_changed,u16,
 msgdata,channeld_sending_commitsig,changed,changed_htlc,num_changed
-msgdata,channeld_sending_commitsig,commit_sig,bitcoin_signature,
-msgdata,channeld_sending_commitsig,num_htlc_sigs,u16,
-msgdata,channeld_sending_commitsig,htlc_sigs,bitcoin_signature,num_htlc_sigs
+
 
 # Wait for reply, to make sure it's on disk before we send commit.
 msgtype,channeld_sending_commitsig_reply,1120

channeld/commit_tx.c

@@ -128,7 +128,8 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 			     u64 obscured_commitment_number,
 			     bool option_anchor_outputs,
 			     bool option_anchors_zero_fee_htlc_tx,
-			     enum side side)
+			     enum side side,
+			     int *anchor_outnum)
 {
 	struct amount_sat base_fee;
 	struct amount_msat total_pay;
@@ -139,7 +140,8 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 	u32 *cltvs;
 	bool to_local, to_remote;
 	struct htlc *dummy_to_local = (struct htlc *)0x01,
-		*dummy_to_remote = (struct htlc *)0x02;
+		*dummy_to_remote = (struct htlc *)0x02,
+		*dummy_other_anchor = (struct htlc *)0x03;
 	const u8 *funding_wscript = bitcoin_redeem_2of2(tmpctx,
 							local_funding_key,
 							remote_funding_key);
@@ -379,9 +381,11 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 			n++;
 		}
 
+		/* With anchors, the caller really wants to know what
+		 * is the LOCAL anchor for the REMOTE side. */
 		if (to_remote || untrimmed != 0) {
 			tx_add_anchor_output(tx, remote_funding_key);
-			(*htlcmap)[n] = NULL;
+			(*htlcmap)[n] = dummy_other_anchor;
 			n++;
 		}
 	}
@@ -433,17 +437,21 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 	bitcoin_tx_add_input(tx, funding,
 			     sequence, NULL, funding_sats, NULL, funding_wscript);
 
-	/* Identify the direct outputs (to_us, to_them). */
-	if (direct_outputs != NULL) {
+	/* Identify the direct outputs (to_us, to_them), and the local anchor */
+	if (direct_outputs != NULL)
 		direct_outputs[LOCAL] = direct_outputs[REMOTE] = NULL;
-		for (size_t i = 0; i < tx->wtx->num_outputs; i++) {
-			if ((*htlcmap)[i] == dummy_to_local) {
-				(*htlcmap)[i] = NULL;
-				direct_outputs[LOCAL] = tx->wtx->outputs + i;
-			} else if ((*htlcmap)[i] == dummy_to_remote) {
-				(*htlcmap)[i] = NULL;
-				direct_outputs[REMOTE] = tx->wtx->outputs + i;
-			}
+
+	*anchor_outnum = -1;
+	for (size_t i = 0; i < tx->wtx->num_outputs; i++) {
+		if ((*htlcmap)[i] == dummy_to_local) {
+			(*htlcmap)[i] = NULL;
+			direct_outputs[LOCAL] = tx->wtx->outputs + i;
+		} else if ((*htlcmap)[i] == dummy_to_remote) {
+			(*htlcmap)[i] = NULL;
+			direct_outputs[REMOTE] = tx->wtx->outputs + i;
+		} else if ((*htlcmap)[i] == dummy_other_anchor) {
+			(*htlcmap)[i] = NULL;
+			*anchor_outnum = i;
 		}
 	}
 

channeld/commit_tx.h

@@ -63,8 +63,9 @@ bool commit_tx_amount_trimmed(const struct htlc **htlcs,
  * @obscured_commitment_number: number to encode in commitment transaction
  * @direct_outputs: If non-NULL, fill with pointers to the direct (non-HTLC) outputs (or NULL if none).
  * @option_anchor_outputs: does option_anchor_outputs apply to this channel?
+ * @option_anchors_zero_fee_htlc_tx: does option_anchors_zero_fee_htlc_tx apply to this channel?
  * @side: side to generate commitment transaction for.
- * @option_anchor_outputs: does option_anchor_outputs apply to this channel?
+ * @anchor_outnum: set to index of local anchor, or -1 if none.
  *
  * We need to be able to generate the remote side's tx to create signatures,
  * but the BOLT is expressed in terms of generating our local commitment
@@ -90,6 +91,7 @@ struct bitcoin_tx *commit_tx(const tal_t *ctx,
 			     u64 obscured_commitment_number,
 			     bool option_anchor_outputs,
 			     bool option_anchors_zero_fee_htlc_tx,
-			     enum side side);
+			     enum side side,
+			     int *anchor_outnum);
 
 #endif /* LIGHTNING_CHANNELD_COMMIT_TX_H */

channeld/full_channel.c

@@ -299,32 +299,18 @@ static void add_htlcs(struct bitcoin_tx ***txs,
 
 /* FIXME: We could cache these. */
 struct bitcoin_tx **channel_txs(const tal_t *ctx,
+				const struct bitcoin_outpoint *funding,
+				struct amount_sat funding_sats,
 				const struct htlc ***htlcmap,
 				struct wally_tx_output *direct_outputs[NUM_SIDES],
 				const u8 **funding_wscript,
 				const struct channel *channel,
 				const struct pubkey *per_commitment_point,
 				u64 commitment_number,
-				enum side side)
-{
-	return channel_splice_txs(ctx, &channel->funding, channel->funding_sats,
-				  htlcmap, direct_outputs, funding_wscript,
-				  channel, per_commitment_point,
-				  commitment_number, side, 0, 0);
-}
-
-struct bitcoin_tx **channel_splice_txs(const tal_t *ctx,
-				       const struct bitcoin_outpoint *funding,
-				       struct amount_sat funding_sats,
-				       const struct htlc ***htlcmap,
-				       struct wally_tx_output *direct_outputs[NUM_SIDES],
-				       const u8 **funding_wscript,
-				       const struct channel *channel,
-				       const struct pubkey *per_commitment_point,
-				       u64 commitment_number,
-				       enum side side,
-				       s64 splice_amnt,
-				       s64 remote_splice_amnt)
+				enum side side,
+				s64 splice_amnt,
+				s64 remote_splice_amnt,
+				int *other_anchor_outnum)
 {
 	struct bitcoin_tx **txs;
 	const struct htlc **committed;
@@ -378,7 +364,7 @@ struct bitcoin_tx **channel_splice_txs(const tal_t *ctx,
 	    commitment_number ^ channel->commitment_number_obscurer,
 	    channel_has(channel, OPT_ANCHOR_OUTPUTS),
 	    channel_has(channel, OPT_ANCHORS_ZERO_FEE_HTLC_TX),
-	    side);
+	    side, other_anchor_outnum);
 
 	/* Set the remote/local pubkeys on the commitment tx psbt */
 	psbt_input_add_pubkey(txs[0]->psbt, 0,