lightningd: set channel's local alias at init.

Rather than having channeld/dualopend do it, we can set it and tell them.

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

channeld/channeld.c

@@ -139,6 +139,9 @@ struct peer {
 	/* Which direction of the channel do we control? */
 	u16 channel_direction;
 
+	/* Local scid alias */
+	struct short_channel_id local_alias;
+
 	/* The scriptpubkey to use for shutting down. */
 	u32 *final_index;
 	struct ext_key *final_ext_key;
@@ -5272,6 +5275,7 @@ static void peer_reconnect(struct peer *peer,
 	    && next_commitment_number == 1) {
 		struct tlv_channel_ready_tlvs *tlvs = tlv_channel_ready_tlvs_new(tmpctx);
 
+		tlvs->short_channel_id = &peer->local_alias;
 		status_debug("Retransmitting channel_ready for channel %s",
 		             type_to_string(tmpctx, struct channel_id, &peer->channel_id));
 		/* Contains per commit point #1, for first post-opening commit */
@@ -5554,7 +5558,7 @@ static void peer_reconnect(struct peer *peer,
 static void handle_funding_depth(struct peer *peer, const u8 *msg)
 {
 	u32 depth;
-	struct short_channel_id *scid, *alias_local;
+	struct short_channel_id *scid;
 	struct tlv_channel_ready_tlvs *tlvs;
 	struct pubkey point;
 	bool splicing;
@@ -5563,7 +5567,6 @@ static void handle_funding_depth(struct peer *peer, const u8 *msg)
 	if (!fromwire_channeld_funding_depth(tmpctx,
 					     msg,
 					     &scid,
-					     &alias_local,
 					     &depth,
 					     &splicing,
 					     &txid))
@@ -5594,15 +5597,15 @@ static void handle_funding_depth(struct peer *peer, const u8 *msg)
 			status_debug("handle_funding_depth: Setting short_channel_ids[LOCAL] to %s",
 				type_to_string(tmpctx,
 					       struct short_channel_id,
-					       (scid ? scid : alias_local)));
+					       (scid ? scid : &peer->local_alias)));
 			/* If we know an actual short_channel_id prefer to use
 			 * that, otherwise fill in the alias. From channeld's
 			 * point of view switching from zeroconf to an actual
 			 * funding scid is just a reorg. */
 			if (scid)
 				peer->short_channel_ids[LOCAL] = *scid;
-			else if (alias_local)
-				peer->short_channel_ids[LOCAL] = *alias_local;
+			else
+				peer->short_channel_ids[LOCAL] = peer->local_alias;
 		}
 
 		if (!peer->channel_ready[LOCAL]) {
@@ -5612,7 +5615,7 @@ static void handle_funding_depth(struct peer *peer, const u8 *msg)
 				     type_to_string(tmpctx, struct pubkey,
 						    &peer->next_local_per_commit));
 			tlvs = tlv_channel_ready_tlvs_new(tmpctx);
-			tlvs->short_channel_id = alias_local;
+			tlvs->short_channel_id = &peer->local_alias;
 
 			/* Need to retrieve the first point again, even if we
 			 * moved on, as channel_ready explicitly includes the
@@ -6166,7 +6169,8 @@ static void init_channel(struct peer *peer)
 				    &pbases,
 				    &reestablish_only,
 				    &peer->experimental_upgrade,
-				    &peer->splice_state->inflights)) {
+				    &peer->splice_state->inflights,
+				    &peer->local_alias)) {
 		master_badmsg(WIRE_CHANNELD_INIT, msg);
 	}
 

channeld/channeld_wire.csv

@@ -81,13 +81,12 @@ msgdata,channeld_init,reestablish_only,bool,
 msgdata,channeld_init,experimental_upgrade,bool,
 msgdata,channeld_init,num_inflights,u16,
 msgdata,channeld_init,inflights,inflight,num_inflights
+msgdata,channeld_init,scid_alias,short_channel_id,
 
 # master->channeld funding hit new depth(funding locked if >= lock depth)
-# alias != NULL if zeroconf and short_channel_id == NULL
 # short_channel_id != NULL once we have 3+ confirmations
 msgtype,channeld_funding_depth,1002
 msgdata,channeld_funding_depth,short_channel_id,?short_channel_id,
-msgdata,channeld_funding_depth,alias_local,?short_channel_id,
 msgdata,channeld_funding_depth,depth,u32,
 msgdata,channeld_funding_depth,splicing,bool,
 msgdata,channeld_funding_depth,txid,bitcoin_txid,

lightningd/channel.c

@@ -17,6 +17,7 @@
 #include <lightningd/opening_common.h>
 #include <lightningd/peer_control.h>
 #include <lightningd/subd.h>
+#include <sodium/randombytes.h>
 #include <wallet/txfilter.h>
 #include <wire/peer_wire.h>
 
@@ -278,7 +279,10 @@ struct channel *new_unsaved_channel(struct peer *peer,
 	channel->closing_feerate_range = NULL;
 	channel->peer_update = NULL;
 	channel->channel_update = NULL;
-	channel->alias[LOCAL] = channel->alias[REMOTE] = NULL;
+	channel->alias[REMOTE] = NULL;
+	/* We don't even bother checking for clashes. */
+	channel->alias[LOCAL] = tal(channel, struct short_channel_id);
+	randombytes_buf(channel->alias[LOCAL], sizeof(struct short_channel_id));
 
 	channel->shutdown_scriptpubkey[REMOTE] = NULL;
 	channel->last_was_revoke = false;
@@ -397,7 +401,7 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 			    bool remote_channel_ready,
 			    /* NULL or stolen */
 			    struct short_channel_id *scid,
-			    struct short_channel_id *alias_local STEALS,
+			    struct short_channel_id *alias_local TAKES,
 			    struct short_channel_id *alias_remote STEALS,
 			    struct channel_id *cid,
 			    struct amount_msat our_msat,
@@ -508,7 +512,7 @@ struct channel *new_channel(struct peer *peer, u64 dbid,
 	channel->our_funds = our_funds;
 	channel->remote_channel_ready = remote_channel_ready;
 	channel->scid = tal_steal(channel, scid);
-	channel->alias[LOCAL] = tal_steal(channel, alias_local);
+	channel->alias[LOCAL] = tal_dup_or_null(channel, struct short_channel_id, alias_local);
 	channel->alias[REMOTE] = tal_steal(channel, alias_remote);  /* Haven't gotten one yet. */
 	channel->cid = *cid;
 	channel->our_msat = our_msat;

lightningd/channel_control.c

@@ -594,7 +594,6 @@ static enum watch_result splice_depth_cb(struct lightningd *ld,
 		subd_send_msg(inflight->channel->owner,
 			      take(towire_channeld_funding_depth(
 					   NULL, &scid,
-					   inflight->channel->alias[LOCAL],
 					   depth, true, txid)));
 	}
 
@@ -1700,7 +1699,8 @@ bool peer_start_channeld(struct channel *channel,
 				       reestablish_only,
 				       ld->experimental_upgrade_protocol,
 				       cast_const2(const struct inflight **,
-						   inflights));
+						   inflights),
+				       channel->alias[LOCAL]);
 
 	/* We don't expect a response: we are triggered by funding_depth_cb. */
 	subd_send_msg(channel->owner, take(initmsg));
@@ -1719,7 +1719,7 @@ bool peer_start_channeld(struct channel *channel,
 	/* Artificial confirmation event for zeroconf */
 	subd_send_msg(channel->owner,
 		      take(towire_channeld_funding_depth(
-			   NULL, channel->scid, channel->alias[LOCAL], 0, false,
+			   NULL, channel->scid, 0, false,
 			   &txid)));
 	return true;
 }
@@ -1742,7 +1742,7 @@ void channeld_tell_depth(struct channel *channel,
 
 	subd_send_msg(channel->owner,
 		      take(towire_channeld_funding_depth(
-			  NULL, channel->scid, channel->alias[LOCAL], depth,
+			  NULL, channel->scid, depth,
 			  false, txid)));
 }
 

lightningd/dual_open_control.c

@@ -33,7 +33,6 @@
 #include <lightningd/peer_fd.h>
 #include <lightningd/plugin_hook.h>
 #include <openingd/dualopend_wiregen.h>
-#include <sodium/randombytes.h>
 
 struct commit_rcvd {
 	struct channel *channel;
@@ -1465,12 +1464,6 @@ wallet_commit_channel(struct lightningd *ld,
 			= p2tr_for_keyidx(channel, channel->peer->ld,
 					    channel->final_key_idx);
 
-	 /* Can't have gotten their alias for this channel yet. */
-	channel->alias[REMOTE] = NULL;
-	/* We do generate one ourselves however. */
-	channel->alias[LOCAL] = tal(channel, struct short_channel_id);
-	randombytes_buf(channel->alias[LOCAL], sizeof(struct short_channel_id));
-
 	channel->remote_upfront_shutdown_script
 		= tal_steal(channel, remote_upfront_shutdown_script);
 
@@ -4055,6 +4048,7 @@ bool peer_start_dualopend(struct peer *peer,
 				    &channel->local_funding_pubkey,
 				    channel->minimum_depth,
 				    peer->ld->config.require_confirmed_inputs,
+				    channel->alias[LOCAL],
 				    peer->ld->dev_any_channel_type);
 	subd_send_msg(channel->owner, take(msg));
 	return true;
@@ -4168,7 +4162,8 @@ bool peer_restart_dualopend(struct peer *peer,
 					      NULL : &inflight->lease_amt,
 				      channel->type,
 				      channel->req_confirmed_ins[LOCAL],
-				      channel->req_confirmed_ins[REMOTE]);
+				      channel->req_confirmed_ins[REMOTE],
+				      channel->alias[LOCAL]);
 
 	subd_send_msg(channel->owner, take(msg));
 	return true;

lightningd/opening_control.c

@@ -112,7 +112,7 @@ wallet_commit_channel(struct lightningd *ld,
 	s64 final_key_idx;
 	u64 static_remotekey_start;
 	u32 lease_start_blockheight = 0; /* No leases on v1 */
-	struct short_channel_id *alias_local;
+	struct short_channel_id local_alias;
 	struct timeabs timestamp;
 	bool any_active = peer_any_channel(uc->peer, channel_state_wants_peercomms, NULL);
 
@@ -174,8 +174,8 @@ wallet_commit_channel(struct lightningd *ld,
 	else
 		static_remotekey_start = 0x7FFFFFFFFFFFFFFF;
 
-	alias_local = tal(NULL, struct short_channel_id);
-	randombytes_buf(alias_local, sizeof(struct short_channel_id));
+	/* This won't clash, we don't even bother checking */
+	randombytes_buf(&local_alias, sizeof(local_alias));
 
 	channel = new_channel(uc->peer, uc->dbid,
 			      NULL, /* No shachain yet */
@@ -194,7 +194,7 @@ wallet_commit_channel(struct lightningd *ld,
 			      local_funding,
 			      false, /* !remote_channel_ready */
 			      NULL, /* no scid yet */
-			      alias_local, /* But maybe we have an alias we want to use? */
+			      &local_alias,
 			      NULL, /* They haven't told us an alias yet */
 			      cid,
 			      /* The three arguments below are msatoshi_to_us,

openingd/dualopend.c

@@ -227,6 +227,9 @@ struct state {
 	/* Does this negotation require confirmed inputs? */
 	bool require_confirmed_inputs[NUM_SIDES];
 
+	/* Our alias */
+	struct short_channel_id local_alias;
+
 	bool dev_accept_any_channel_type;
 };
 
@@ -3869,6 +3872,7 @@ static void send_channel_ready(struct state *state)
 	/* Figure out the next local commit */
 	hsm_per_commitment_point(1, &next_local_per_commit);
 
+	tlvs->short_channel_id = &state->local_alias;
 	msg = towire_channel_ready(NULL, &state->channel_id,
 				    &next_local_per_commit, tlvs);
 	peer_write(state->pps, take(msg));
@@ -4382,6 +4386,7 @@ int main(int argc, char *argv[])
 				    &state->our_funding_pubkey,
 				    &state->minimum_depth,
 				    &state->require_confirmed_inputs[LOCAL],
+				    &state->local_alias,
 				    &state->dev_accept_any_channel_type)) {
 		/*~ Initially we're not associated with a channel, but
 		 * handle_peer_gossip_or_error compares this. */
@@ -4446,7 +4451,8 @@ int main(int argc, char *argv[])
 					     &requested_lease,
 					     &state->channel_type,
 					     &state->require_confirmed_inputs[LOCAL],
-					     &state->require_confirmed_inputs[REMOTE])) {
+					     &state->require_confirmed_inputs[REMOTE],
+					     &state->local_alias)) {
 
 		bool ok;
 

openingd/dualopend_wire.csv

@@ -29,6 +29,7 @@ msgdata,dualopend_init,our_funding_pubkey,pubkey,
 # Constraints in case the other end tries to open a channel.
 msgdata,dualopend_init,minimum_depth,u32,
 msgdata,dualopend_init,require_confirmed_inputs,bool,
+msgdata,dualopend_init,local_alias,short_channel_id,
 msgdata,dualopend_init,dev_accept_any_channel_type,bool,
 
 # master-dualopend: peer has reconnected
@@ -77,6 +78,7 @@ msgdata,dualopend_reinit,requested_lease,?amount_sat,
 msgdata,dualopend_reinit,channel_type,channel_type,
 msgdata,dualopend_reinit,we_require_confirmed_inputs,bool,
 msgdata,dualopend_reinit,they_require_confirmed_inputs,bool,
+msgdata,dualopend_reinit,local_alias,short_channel_id,
 
 # dualopend->master: they offered channel, should we continue?
 msgtype,dualopend_got_offer,7005