common/channel_type: routines to set known variants, set scid_alias.

I tested this indeed breaks if we don't accept it, then implemented
the code to accept it.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Fixed: protocol: We now correctly accept the `option_scid_alias` bit in `open_channel` `channel_type`.
Changelog-Deprecated: protocol: Not setting `option_scid_alias` in `option_channel` `channel_type` for unannounced channels.

common/channel_type.c

@@ -43,6 +43,18 @@ struct channel_type *channel_type_anchor_outputs(const tal_t *ctx)
 	return type;
 }
 
+void channel_type_set_zeroconf(struct channel_type *type)
+{
+	set_feature_bit(&type->features,
+			COMPULSORY_FEATURE(OPT_ZEROCONF));
+}
+
+void channel_type_set_scid_alias(struct channel_type *type)
+{
+	set_feature_bit(&type->features,
+			COMPULSORY_FEATURE(OPT_SCID_ALIAS));
+}
+
 struct channel_type *default_channel_type(const tal_t *ctx,
 					  const struct feature_set *our_features,
 					  const u8 *their_features)
@@ -119,6 +131,7 @@ struct channel_type *channel_type_accept(const tal_t *ctx,
 	static const size_t feats[] = {
 		OPT_ANCHOR_OUTPUTS,
 		OPT_STATIC_REMOTEKEY,
+		OPT_SCID_ALIAS,
 		OPT_ZEROCONF,
 	};
 
@@ -128,6 +141,7 @@ struct channel_type *channel_type_accept(const tal_t *ctx,
 	 *   - `option_zeroconf` (bit 50)
 	 */
 	static const size_t variants[] = {
+		OPT_SCID_ALIAS,
 		OPT_ZEROCONF,
 	};
 

common/channel_type.h

@@ -10,6 +10,10 @@ struct channel_type *channel_type_none(const tal_t *ctx);
 struct channel_type *channel_type_static_remotekey(const tal_t *ctx);
 struct channel_type *channel_type_anchor_outputs(const tal_t *ctx);
 
+/* channel_type variants */
+void channel_type_set_zeroconf(struct channel_type *channel_type);
+void channel_type_set_scid_alias(struct channel_type *channel_type);
+
 /* Duplicate a channel_type */
 struct channel_type *channel_type_dup(const tal_t *ctx,
 				      const struct channel_type *t);

doc/lightning-listpeerchannels.7.md

@@ -29,7 +29,7 @@ On success, an object containing **channels** is returned.  It is an array of ob
 - **state** (string): the channel state, in particular "CHANNELD\_NORMAL" means the channel can be used normally (one of "OPENINGD", "CHANNELD\_AWAITING\_LOCKIN", "CHANNELD\_NORMAL", "CHANNELD\_SHUTTING\_DOWN", "CLOSINGD\_SIGEXCHANGE", "CLOSINGD\_COMPLETE", "AWAITING\_UNILATERAL", "FUNDING\_SPEND\_SEEN", "ONCHAIN", "DUALOPEND\_OPEN\_INIT", "DUALOPEND\_AWAITING\_LOCKIN")
 - **opener** (string): Who initiated the channel (one of "local", "remote")
 - **features** (array of strings):
-  - BOLT #9 features which apply to this channel (one of "option\_static\_remotekey", "option\_anchor\_outputs", "option\_zeroconf")
+  - BOLT #9 features which apply to this channel (one of "option\_static\_remotekey", "option\_anchor\_outputs", "option\_scid\_alias", "option\_zeroconf")
 - **scratch\_txid** (txid, optional): The txid we would use if we went onchain now
 - **channel\_type** (object, optional): channel\_type as negotiated with peer *(added v23.05)*:
   - **bits** (array of u32s): Each bit set in this channel\_type:
@@ -194,4 +194,4 @@ Main web site: <https://github.com/ElementsProject/lightning> Lightning
 RFC site (BOLT \#9):
 <https://github.com/lightningnetwork/lightning-rfc/blob/master/09-features.md>
 
-[comment]: # ( SHA256STAMP:1e589a9e6eace9134d04693dd00caa03da98dd40c2e65d3c675c9bee06daff7f)
+[comment]: # ( SHA256STAMP:98524b075be2355d84732638277bf125549bc7ca21822ed35e1ffd1dff53d7f7)

doc/lightning-listpeers.7.md

@@ -69,7 +69,7 @@ On success, an object containing **peers** is returned.  It is an array of objec
   - **state** (string): the channel state, in particular "CHANNELD\_NORMAL" means the channel can be used normally (one of "OPENINGD", "CHANNELD\_AWAITING\_LOCKIN", "CHANNELD\_NORMAL", "CHANNELD\_SHUTTING\_DOWN", "CLOSINGD\_SIGEXCHANGE", "CLOSINGD\_COMPLETE", "AWAITING\_UNILATERAL", "FUNDING\_SPEND\_SEEN", "ONCHAIN", "DUALOPEND\_OPEN\_INIT", "DUALOPEND\_AWAITING\_LOCKIN")
   - **opener** (string): Who initiated the channel (one of "local", "remote")
   - **features** (array of strings):
-    - BOLT #9 features which apply to this channel (one of "option\_static\_remotekey", "option\_anchor\_outputs", "option\_zeroconf")
+    - BOLT #9 features which apply to this channel (one of "option\_static\_remotekey", "option\_anchor\_outputs", "option\_scid\_alias", "option\_zeroconf")
   - **scratch\_txid** (txid, optional): The txid we would use if we went onchain now
   - **feerate** (object, optional): Feerates for the current tx:
     - **perkw** (u32): Feerate per 1000 weight (i.e kSipa)
@@ -398,4 +398,4 @@ Main web site: <https://github.com/ElementsProject/lightning> Lightning
 RFC site (BOLT \#9):
 <https://github.com/lightning/bolts/blob/master/09-features.md>
 
-[comment]: # ( SHA256STAMP:156e5622823a8b948c0f15f694afc1d87bb5107091e5b65ee6190b4067661bb4)
+[comment]: # ( SHA256STAMP:c0d0cc8f083168fd76caa2430a7c7d27d72a5273c55fb14b0efcbcb7a87274f4)

doc/schemas/listpeerchannels.schema.json

@@ -211,6 +211,7 @@
               "enum": [
                 "option_static_remotekey",
                 "option_anchor_outputs",
+                "option_scid_alias",
                 "option_zeroconf"
               ],
               "description": "BOLT #9 features which apply to this channel"

doc/schemas/listpeers.schema.json

@@ -334,6 +334,7 @@
                     "enum": [
                       "option_static_remotekey",
                       "option_anchor_outputs",
+                      "option_scid_alias",
                       "option_zeroconf"
                     ],
                     "description": "BOLT #9 features which apply to this channel"

lightningd/opening_control.c

@@ -964,7 +964,8 @@ bool peer_start_openingd(struct peer *peer, struct peer_fd *peer_fd)
 				   feerate_min(peer->ld, NULL),
 				   feerate_max(peer->ld, NULL),
 				   IFDEV(peer->ld->dev_force_tmp_channel_id, NULL),
-				   peer->ld->config.allowdustreserve);
+				   peer->ld->config.allowdustreserve,
+				   !deprecated_apis);
 	subd_send_msg(uc->open_daemon, take(msg));
 	return true;
 }

lightningd/peer_control.c

@@ -866,6 +866,8 @@ static void json_add_channel(struct lightningd *ld,
 		json_add_string(response, NULL, "option_anchor_outputs");
 	if (channel_has(channel, OPT_ZEROCONF))
 		json_add_string(response, NULL, "option_zeroconf");
+	if (channel_has(channel, OPT_SCID_ALIAS))
+		json_add_string(response, NULL, "option_scid_alias");
 	json_array_end(response);
 
 	if (!amount_sat_sub(&peer_funded_sats, channel->funding_sats,

openingd/openingd.c

@@ -102,6 +102,9 @@ struct state {
 	struct amount_sat *reserve;
 
 	bool allowdustreserve;
+
+	/* Are we allowed to set option_scid_alias is channel_type? */
+	bool can_set_scid_alias_channel_type;
 };
 
 /*~ If we can't agree on parameters, we fail to open the channel.
@@ -332,6 +335,14 @@ static u8 *funder_channel_start(struct state *state, u8 channel_flags)
 						   state->our_features,
 						   state->their_features);
 
+	/* Spec says we should use the option_scid_alias variation if we
+	 * want them to *only* use the scid_alias.  But we didn't accept this
+	 * in CLN prior to v23.05, so we don't send that in deprecated mode! */
+	if (state->can_set_scid_alias_channel_type) {
+		if (!(channel_flags & CHANNEL_FLAGS_ANNOUNCE_CHANNEL))
+			channel_type_set_scid_alias(state->channel_type);
+	}
+
 	open_tlvs = tlv_open_channel_tlvs_new(tmpctx);
 	open_tlvs->upfront_shutdown_script
 		= state->upfront_shutdown_script[LOCAL];
@@ -902,6 +913,16 @@ static u8 *fundee_channel(struct state *state, const u8 *open_channel_msg)
 							   open_tlvs->channel_type));
 			return NULL;
 		}
+
+		/* If we're not using scid_alias in channel type, intuit it here.
+		 * We have to do this, because we used not to accept that bit, so older
+		 * clients won't send it! */
+		if (!state->can_set_scid_alias_channel_type
+		    && !(channel_flags & CHANNEL_FLAGS_ANNOUNCE_CHANNEL)
+		    && feature_negotiated(state->our_features, state->their_features,
+					  OPT_SCID_ALIAS)) {
+			channel_type_set_scid_alias(state->channel_type);
+		}
 	} else
 		state->channel_type
 			= default_channel_type(state,
@@ -1453,7 +1474,8 @@ int main(int argc, char *argv[])
 				    &state->minimum_depth,
 				    &state->min_feerate, &state->max_feerate,
 				    &force_tmp_channel_id,
-				    &state->allowdustreserve))
+				    &state->allowdustreserve,
+				    &state->can_set_scid_alias_channel_type))
 		master_badmsg(WIRE_OPENINGD_INIT, msg);
 
 #if DEVELOPER

openingd/openingd_wire.csv

@@ -28,6 +28,8 @@ msgdata,openingd_init,dev_temporary_channel_id,?byte,32
 # reserves? This is explicitly required by the spec for safety
 # reasons, but some implementations and users keep asking for it.
 msgdata,openingd_init,allowdustreserve,bool,
+# Core LN prior to 23.05 didn't like this bit set!
+msgdata,openingd_init,can_set_scid_alias_channel_type,bool,
 
 # Openingd->master: they offered channel, should we continue?
 msgtype,openingd_got_offer,6005