splice: Implement start_batch

Implement the sending of `start_batch` as per t-bast’s spec. We ignoring it when receving, as we don’t need it.

Changelog-Added: support for `start_batch`

Author: ddustin

channeld/channeld.c

@@ -1274,6 +1274,44 @@ static s64 sats_diff(struct amount_sat a, struct amount_sat b)
         return (s64)a.satoshis - (s64)b.satoshis; /* Raw: splicing numbers can wrap! */
 }
 
+static void send_message_batch(struct peer *peer, u8 **msgs)
+{
+	size_t size;
+	u8 *batch_msg, *final_msg, *final_msg_ptr;
+
+	size = 0;
+	for(u32 i = 0; i < tal_count(msgs); i++)
+		size += tal_bytelen(msgs[i]);
+
+	/* Only append `start_batch` if batch is more than 1 */
+	if (tal_count(msgs) > 1) {
+		batch_msg = towire_start_batch(NULL, &peer->channel_id,
+					       tal_count(msgs));
+		size += tal_bytelen(batch_msg);
+	}
+
+	/* Now we know the size of our `final_msg` so we allocate. */
+	final_msg = tal_arr(NULL, u8, size);
+	final_msg_ptr = final_msg;
+
+	/* Append the `start_batch` here, again if batch is more than 1 */
+	if (tal_count(msgs) > 1) {
+		memcpy(final_msg_ptr, batch_msg, tal_bytelen(batch_msg));
+		final_msg_ptr += tal_bytelen(batch_msg);
+		tal_free(batch_msg);
+	}
+
+	/* Now copy the bytes from all messages in `msgs` */
+	for(u32 i = 0; i < tal_count(msgs); i++) {
+		memcpy(final_msg_ptr, msgs[i], tal_bytelen(msgs[i]));
+		final_msg_ptr += tal_bytelen(msgs[i]);
+	}
+
+	assert(final_msg + size == final_msg_ptr);
+	peer_write(peer->pps, final_msg);
+	tal_free(final_msg);
+}
+
 static void send_commit(struct peer *peer)
 {
 	const struct htlc **changed_htlcs;
@@ -1440,8 +1478,7 @@ static void send_commit(struct peer *peer)
 
 	peer->next_index[REMOTE]++;
 
-	for(u32 i = 0; i < tal_count(msgs); i++)
-		peer_write(peer->pps, take(msgs[i]));
+	send_message_batch(peer, msgs);
 
 	maybe_send_shutdown(peer);
 
@@ -4850,6 +4887,9 @@ static void peer_in(struct peer *peer, const u8 *msg)
 	case WIRE_UPDATE_ADD_HTLC:
 		handle_peer_add_htlc(peer, msg);
 		return;
+	case WIRE_START_BATCH:
+		/* We can safely ignore these messages as we dont need them. */
+		return;
 	case WIRE_COMMITMENT_SIGNED:
 		handle_peer_commit_sig_batch(peer, msg, 0,
 					     peer->channel->funding_pubkey[REMOTE],

common/gossmap.c

@@ -1799,6 +1799,7 @@ const void *gossmap_stream_next(const tal_t *ctx,
 		case WIRE_UPDATE_FULFILL_HTLC:
 		case WIRE_UPDATE_FAIL_HTLC:
 		case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+		case WIRE_START_BATCH:
 		case WIRE_COMMITMENT_SIGNED:
 		case WIRE_REVOKE_AND_ACK:
 		case WIRE_UPDATE_FEE:

common/interactivetx.c

@@ -163,6 +163,7 @@ static u8 *read_next_msg(const tal_t *ctx,
 		case WIRE_UPDATE_FULFILL_HTLC:
 		case WIRE_UPDATE_FAIL_HTLC:
 		case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+		case WIRE_START_BATCH:
 		case WIRE_COMMITMENT_SIGNED:
 		case WIRE_REVOKE_AND_ACK:
 		case WIRE_UPDATE_FEE:
@@ -771,6 +772,7 @@ char *process_interactivetx_updates(const tal_t *ctx,
 		case WIRE_UPDATE_FULFILL_HTLC:
 		case WIRE_UPDATE_FAIL_HTLC:
 		case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+		case WIRE_START_BATCH:
 		case WIRE_COMMITMENT_SIGNED:
 		case WIRE_REVOKE_AND_ACK:
 		case WIRE_UPDATE_FEE:

connectd/gossip_rcvd_filter.c

@@ -73,6 +73,7 @@ static bool is_msg_gossip_broadcast(const u8 *cursor)
 	case WIRE_UPDATE_FULFILL_HTLC:
 	case WIRE_UPDATE_FAIL_HTLC:
 	case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+	case WIRE_START_BATCH:
 	case WIRE_COMMITMENT_SIGNED:
 	case WIRE_REVOKE_AND_ACK:
 	case WIRE_UPDATE_FEE:

connectd/gossip_store.c

@@ -82,6 +82,7 @@ static bool public_msg_type(enum peer_wire type)
 	case WIRE_UPDATE_FULFILL_HTLC:
 	case WIRE_UPDATE_FAIL_HTLC:
 	case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+	case WIRE_START_BATCH:
 	case WIRE_COMMITMENT_SIGNED:
 	case WIRE_REVOKE_AND_ACK:
 	case WIRE_UPDATE_FEE:

connectd/multiplex.c

@@ -382,6 +382,7 @@ static bool is_urgent(enum peer_wire type)
 	/* These are time-sensitive, and so send without delay. */
 	case WIRE_PING:
 	case WIRE_PONG:
+	case WIRE_START_BATCH:
 	case WIRE_COMMITMENT_SIGNED:
 	case WIRE_REVOKE_AND_ACK:
 		return true;
@@ -440,6 +441,10 @@ static struct io_plan *encrypt_and_send(struct peer *peer,
 
 	set_urgent_flag(peer, is_urgent(type));
 
+	/* DTODO: If needed, split start_batch message back into multiple
+	 * individual write events. Currently we send all messages in the batch
+	 * in a single write event. */
+
 	/* We free this and the encrypted version in next write_to_peer */
 	peer->sent_to_peer = cryptomsg_encrypt_msg(peer, &peer->cs, msg);
 	return io_write(peer->to_peer,

gossipd/gossipd.c

@@ -244,6 +244,7 @@ static void handle_recv_gossip(struct daemon *daemon, const u8 *outermsg)
 	case WIRE_UPDATE_FULFILL_HTLC:
 	case WIRE_UPDATE_FAIL_HTLC:
 	case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+	case WIRE_START_BATCH:
 	case WIRE_COMMITMENT_SIGNED:
 	case WIRE_REVOKE_AND_ACK:
 	case WIRE_UPDATE_FEE:

openingd/dualopend.c

@@ -1673,6 +1673,7 @@ static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state)
 		case WIRE_UPDATE_FULFILL_HTLC:
 		case WIRE_UPDATE_FAIL_HTLC:
 		case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+		case WIRE_START_BATCH:
 		case WIRE_COMMITMENT_SIGNED:
 		case WIRE_REVOKE_AND_ACK:
 		case WIRE_UPDATE_FEE:
@@ -2057,6 +2058,7 @@ static bool run_tx_interactive(struct state *state,
 		case WIRE_UPDATE_FULFILL_HTLC:
 		case WIRE_UPDATE_FAIL_HTLC:
 		case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+		case WIRE_START_BATCH:
 		case WIRE_COMMITMENT_SIGNED:
 		case WIRE_REVOKE_AND_ACK:
 		case WIRE_UPDATE_FEE:
@@ -4209,6 +4211,9 @@ static u8 *handle_peer_in(struct state *state)
 		}
 		accepter_start(state, msg);
 		return NULL;
+	case WIRE_START_BATCH:
+		/* We ignore batch messages as we dont need them */
+		return NULL;
 	case WIRE_COMMITMENT_SIGNED:
 		handle_commit_signed(state, msg);
 		return NULL;

wire/peer_wire.c

@@ -21,6 +21,7 @@ static bool unknown_type(enum peer_wire t)
 	case WIRE_UPDATE_FULFILL_HTLC:
 	case WIRE_UPDATE_FAIL_HTLC:
 	case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+	case WIRE_START_BATCH:
 	case WIRE_COMMITMENT_SIGNED:
 	case WIRE_REVOKE_AND_ACK:
 	case WIRE_UPDATE_FEE:
@@ -89,6 +90,7 @@ bool is_msg_for_gossipd(const u8 *cursor)
 	case WIRE_UPDATE_FULFILL_HTLC:
 	case WIRE_UPDATE_FAIL_HTLC:
 	case WIRE_UPDATE_FAIL_MALFORMED_HTLC:
+	case WIRE_START_BATCH:
 	case WIRE_COMMITMENT_SIGNED:
 	case WIRE_REVOKE_AND_ACK:
 	case WIRE_UPDATE_FEE:
@@ -345,6 +347,11 @@ bool extract_channel_id(const u8 *in_pkt, struct channel_id *channel_id)
 		 * 2. data:
 		 *    * [`channel_id`:`channel_id`]
 		 */
+	case WIRE_START_BATCH:
+		/* 1. type: 127 (`start_batch`)
+		 * 2. data:
+		 *    * [`channel_id`:`channel_id`]
+		 */
 	case WIRE_COMMITMENT_SIGNED:
 		/* BOLT #2:
 		 * 1. type: 132 (`commitment_signed`)

wire/peer_wire.csv

@@ -293,6 +293,9 @@ msgdata,update_fail_malformed_htlc,channel_id,channel_id,
 msgdata,update_fail_malformed_htlc,id,u64,
 msgdata,update_fail_malformed_htlc,sha256_of_onion,sha256,
 msgdata,update_fail_malformed_htlc,failure_code,u16,
+msgtype,start_batch,127
+msgdata,start_batch,channel_id,channel_id,
+msgdata,start_batch,batch_size,u16,
 msgtype,commitment_signed,132
 msgdata,commitment_signed,channel_id,channel_id,
 msgdata,commitment_signed,signature,signature,