fundchannel_start / openchannel_init: add a channel_type parameter to force channel type.

And add request schemas for openchannel_init and fundchannel_start.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: JSON-RPC: `fundchannel_start` and `openchannel_init` now take an optional `channel_type` parameter.

contrib/pyln-client/pyln/client/lightning.py

@@ -787,7 +787,7 @@ class LightningRpc(UnixDomainSocketRpc):
         return self.call("fundchannel", payload)
 
     def fundchannel_start(self, node_id, amount, feerate=None, announce=True,
-                          close_to=None, mindepth: Optional[int] = None):
+                          close_to=None, mindepth: Optional[int] = None, channel_type=None):
         """
         Start channel funding with {id} for {amount} satoshis
         with feerate of {feerate} (uses default feerate if unset).
@@ -804,6 +804,7 @@ class LightningRpc(UnixDomainSocketRpc):
             "announce": announce,
             "close_to": close_to,
             "mindepth": mindepth,
+            "channel_type": channel_type,
         }
         return self.call("fundchannel_start", payload)
 
@@ -1104,7 +1105,7 @@ class LightningRpc(UnixDomainSocketRpc):
         }
         return self.call("pay", payload)
 
-    def openchannel_init(self, node_id, channel_amount, psbt, feerate=None, funding_feerate=None, announce=True, close_to=None, request_amt=None, *args, **kwargs):
+    def openchannel_init(self, node_id, channel_amount, psbt, feerate=None, funding_feerate=None, announce=True, close_to=None, request_amt=None, channel_type=None):
         """Initiate an openchannel with a peer """
         payload = {
             "id": node_id,
@@ -1115,6 +1116,7 @@ class LightningRpc(UnixDomainSocketRpc):
             "announce": announce,
             "close_to": close_to,
             "request_amt": request_amt,
+            "channel_type": channel_type,
         }
         return self.call("openchannel_init", payload)
 

doc/lightning-fundchannel_start.7.md

@@ -4,7 +4,7 @@ lightning-fundchannel\_start -- Command for initiating channel establishment for
 SYNOPSIS
 --------
 
-**fundchannel\_start** *id* *amount* [*feerate* *announce* *close\_to* *push\_msat*]
+**fundchannel\_start** *id* *amount* [*feerate*] [*announce*] [*close\_to*] [*push\_msat*] [*channel\_type*]
 
 DESCRIPTION
 -----------
@@ -34,6 +34,21 @@ open. Note that this is a gift to the peer -- these satoshis are
 added to the initial balance of the peer at channel start and are largely
 unrecoverable once pushed.
 
+*channel\_type* *(added v24.02)* is an array of bit numbers, representing the explicit
+channel type to request.  BOLT 2 defines the following value types:
+
+```
+The currently defined basic types are:
+  - no features (no bits set) `[]`
+  - `option_static_remotekey` (`[12]`)
+  - `option_anchor_outputs` and `option_static_remotekey` (`[20, 12]`)
+  - `option_anchors_zero_fee_htlc_tx` and `option_static_remotekey` ([22, 12])
+
+Each basic type has the following variations allowed:
+  - `option_scid_alias` ([46])
+  - `option_zeroconf` ([50])
+```
+
 Note that the funding transaction MUST NOT be broadcast until after
 channel establishment has been successfully completed by running
 `fundchannel_complete`, as the commitment transactions for this channel

doc/lightning-openchannel_init.7.md

@@ -4,7 +4,7 @@ lightning-openchannel\_init -- Command to initiate a channel to a peer
 SYNOPSIS
 --------
 
-**openchannel\_init** *id* *amount* *initalpsbt* [*commitment\_feerate*] [*funding\_feerate*] [*announce*] [*close\_to*] [*request\_amt*] [*compact\_lease*]
+**openchannel\_init** *id* *amount* *initalpsbt* [*commitment\_feerate*] [*funding\_feerate*] [*announce*] [*close\_to*] [*request\_amt*] [*compact\_lease*] [*channel\_type*]
 
 DESCRIPTION
 -----------
@@ -47,6 +47,19 @@ much liquidity into the channel. Must also pass in *compact\_lease*.
 channel lease terms. If the peer's terms don't match this set, we will
 fail to open the channel.
 
+*channel\_type* *(added v24.02)* is an array of bit numbers, representing the explicit
+channel type to request.  BOLT 2 defines the following value types:
+
+The currently defined basic types are:
+  - no features (no bits set) `[]`
+  - `option_static_remotekey` (`[12]`)
+  - `option_anchor_outputs` and `option_static_remotekey` (`[20, 12]`)
+  - `option_anchors_zero_fee_htlc_tx` and `option_static_remotekey` ([22, 12])
+
+Each basic type has the following variations allowed:
+  - `option_scid_alias` ([46])
+  - `option_zeroconf` ([50])
+```
 
 RETURN VALUE
 ------------

doc/schemas/fundchannel_start.request.json

@@ -0,0 +1,43 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "object",
+  "additionalProperties": false,
+  "required": [
+    "id",
+    "amount"
+  ],
+  "properties": {
+    "id": {
+      "type": "pubkey"
+    },
+    "amount": {
+      "type": "msat"
+    },
+    "feerate": {
+      "type": "feerate"
+    },
+    "announce": {
+      "type": "boolean"
+    },
+    "close_to": {
+      "type": "hex"
+    },
+    "push_msat": {
+      "type": "msat"
+    },
+    "mindepth": {
+      "type": "u32"
+    },
+    "reserve": {
+      "type": "msat"
+    },
+    "channel_type": {
+      "type": "array",
+      "description": "Each bit set in this channel_type",
+      "items": {
+        "type": "u32",
+        "description": "Bit number"
+      }
+    }
+  }
+}

doc/schemas/openchannel_init.request.json

@@ -0,0 +1,47 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "type": "object",
+  "additionalProperties": false,
+  "required": [
+    "id",
+    "amount",
+    "initialpsbt"
+  ],
+  "properties": {
+    "id": {
+      "type": "pubkey"
+    },
+    "amount": {
+      "type": "msat"
+    },
+    "initialpsbt": {
+      "type": "string"
+    },
+    "commitment_feerate": {
+      "type": "feerate"
+    },
+    "funding_feerate": {
+      "type": "feerate"
+    },
+    "announce": {
+      "type": "boolean"
+    },
+    "close_to": {
+      "type": "hex"
+    },
+    "request_amt": {
+      "type": "msat"
+    },
+    "compact_lease": {
+      "type": "hex"
+    },
+    "channel_type": {
+      "type": "array",
+      "description": "Each bit set in this channel_type",
+      "items": {
+        "type": "u32",
+        "description": "Bit number"
+      }
+    }
+  }
+}

lightningd/Makefile

@@ -113,6 +113,7 @@ LIGHTNINGD_COMMON_OBJS :=			\
 	common/invoice_path_id.o		\
 	common/key_derive.o			\
 	common/keyset.o				\
+	common/json_channel_type.o		\
 	common/json_filter.o			\
 	common/json_param.o			\
 	common/json_parse.o			\

lightningd/dual_open_control.c

@@ -9,6 +9,7 @@
 #include <ccan/mem/mem.h>
 #include <ccan/tal/str/str.h>
 #include <common/blockheight_states.h>
+#include <common/json_channel_type.h>
 #include <common/json_command.h>
 #include <common/json_param.h>
 #include <common/psbt_open.h>
@@ -3031,6 +3032,7 @@ static struct command_result *json_openchannel_init(struct command *cmd,
 	struct open_attempt *oa;
 	struct lease_rates *rates;
 	struct command_result *res;
+	struct channel_type *ctype;
 	int fds[2];
 
 	if (!param_check(cmd, buffer, params,
@@ -3043,6 +3045,7 @@ static struct command_result *json_openchannel_init(struct command *cmd,
 			 p_opt("close_to", param_bitcoin_address, &our_upfront_shutdown_script),
 			 p_opt_def("request_amt", param_sat, &request_amt, AMOUNT_SAT(0)),
 			 p_opt("compact_lease", param_lease_hex, &rates),
+			 p_opt("channel_type", param_channel_type, &ctype),
 			 NULL))
 		return command_param_failed();
 
@@ -3103,6 +3106,14 @@ static struct command_result *json_openchannel_init(struct command *cmd,
 				    "by peer");
 	}
 
+	if (ctype &&
+	    !channel_type_accept(tmpctx,
+				 ctype->features,
+				 cmd->ld->our_features)) {
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+				    "channel_type not supported");
+	}
+
 	/* BOLT #2:
 	 *  - if both nodes advertised `option_support_large_channel`:
 	 *    - MAY set `funding_satoshis` greater than or equal to 2^24 satoshi.
@@ -3194,6 +3205,7 @@ static struct command_result *json_openchannel_init(struct command *cmd,
 						NULL : request_amt,
 					   get_block_height(cmd->ld->topology),
 					   false,
+					   ctype,
 					   rates);
 
 	/* Start dualopend! */
@@ -3765,7 +3777,7 @@ static struct command_result *json_queryrates(struct command *cmd,
 						NULL : request_amt,
 					   get_block_height(cmd->ld->topology),
 					   true,
-					   NULL);
+					   NULL, NULL);
 
 	if (socketpair(AF_LOCAL, SOCK_STREAM, 0, fds) != 0) {
 		return command_fail(cmd, FUND_MAX_EXCEEDED,

lightningd/opening_control.c

@@ -8,6 +8,7 @@
 #include <common/blockheight_states.h>
 #include <common/configdir.h>
 #include <common/fee_states.h>
+#include <common/json_channel_type.h>
 #include <common/json_command.h>
 #include <common/json_param.h>
 #include <common/memleak.h>
@@ -1148,6 +1149,7 @@ static struct command_result *json_fundchannel_start(struct command *cmd,
 	struct amount_msat *push_msat;
 	u32 *upfront_shutdown_script_wallet_index;
 	struct channel_id tmp_channel_id;
+	struct channel_type *ctype;
 
 	fc->cmd = cmd;
 	fc->cancels = tal_arr(fc, struct command *, 0);
@@ -1164,9 +1166,18 @@ static struct command_result *json_fundchannel_start(struct command *cmd,
 			 p_opt("push_msat", param_msat, &push_msat),
 			 p_opt_def("mindepth", param_u32, &mindepth, cmd->ld->config.anchor_confirms),
 			 p_opt("reserve", param_sat, &reserve),
+			 p_opt("channel_type", param_channel_type, &ctype),
 			 NULL))
 		return command_param_failed();
 
+	if (ctype &&
+	    !channel_type_accept(tmpctx,
+				 ctype->features,
+				 cmd->ld->our_features)) {
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+				    "channel_type not supported");
+	}
+
 	if (push_msat && amount_msat_greater_sat(*push_msat, *amount))
 		return command_fail(cmd, FUND_CANNOT_AFFORD,
 				    "Requested to push_msat of %s is greater than "
@@ -1307,7 +1318,8 @@ static struct command_result *json_fundchannel_start(struct command *cmd,
 			unilateral_feerate(cmd->ld->topology, true),
 			&tmp_channel_id,
 			fc->channel_flags,
-			fc->uc->reserve);
+			fc->uc->reserve,
+			ctype);
 
 	if (socketpair(AF_LOCAL, SOCK_STREAM, 0, fds) != 0) {
 		return command_fail(cmd, FUND_MAX_EXCEEDED,

openingd/dualopend.c

@@ -2952,6 +2952,7 @@ static void opener_start(struct state *state, u8 *msg)
 	struct amount_sat *requested_lease;
 	size_t locktime;
 	u32 nonanchor_feerate, anchor_feerate;
+	struct channel_type *ctype;
 
 	if (!fromwire_dualopend_opener_init(state, msg,
 					    &tx_state->psbt,
@@ -2965,6 +2966,7 @@ static void opener_start(struct state *state, u8 *msg)
 					    &requested_lease,
 					    &tx_state->blockheight,
 					    &dry_run,
+					    &ctype,
 					    &expected_rates))
 		master_badmsg(WIRE_DUALOPEND_OPENER_INIT, msg);
 
@@ -2981,9 +2983,13 @@ static void opener_start(struct state *state, u8 *msg)
 	 *     - SHOULD NOT set it to a type containing a feature which was not
 	 *       negotiated.
 	 */
-	state->channel_type = default_channel_type(state,
+	if (ctype) {
+		state->channel_type = ctype;
+	} else {
+		state->channel_type = default_channel_type(state,
 						   state->our_features,
 						   state->their_features);
+	}
 	open_tlv->channel_type = state->channel_type->features;
 
 	/* Given channel type, which feerate do we use? */

openingd/dualopend_wire.csv

@@ -202,6 +202,7 @@ msgdata,dualopend_opener_init,channel_flags,u8,
 msgdata,dualopend_opener_init,requested_sats,?amount_sat,
 msgdata,dualopend_opener_init,blockheight,u32,
 msgdata,dualopend_opener_init,dry_run,bool,
+msgdata,dualopend_opener_init,channel_type,?channel_type,
 # must go last because embedded tu32
 msgdata,dualopend_opener_init,expected_rates,?lease_rates,
 

openingd/openingd.c

@@ -301,7 +301,8 @@ static bool intuit_scid_alias_type(struct state *state, u8 channel_flags,
 /* We start the 'open a channel' negotation with the supplied peer, but
  * stop when we get to the part where we need the funding txid */
 static u8 *funder_channel_start(struct state *state, u8 channel_flags,
-				u32 nonanchor_feerate, u32 anchor_feerate)
+				u32 nonanchor_feerate, u32 anchor_feerate,
+				const struct channel_type *ctype)
 {
 	u8 *msg;
 	u8 *funding_output_script;
@@ -330,23 +331,27 @@ static u8 *funder_channel_start(struct state *state, u8 channel_flags,
 						     state->our_features,
 						     state->their_features);
 
-	state->channel_type = default_channel_type(state,
-						   state->our_features,
-						   state->their_features);
+	if (ctype) {
+		state->channel_type = channel_type_dup(state, ctype);
+	} else {
+		state->channel_type = default_channel_type(state,
+							   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 (which we do for unannounced
-	 * channels!).
-	 *
-	 * But:
-	 * 1. We didn't accept this in CLN prior to v23.05.
-	 * 2. LND won't accept that without OPT_ANCHORS_ZERO_FEE_HTLC_TX.
-	 *
-	 * So we keep it off for now, until anchors merge.
-	 */
-	if (channel_type_has(state->channel_type, OPT_ANCHORS_ZERO_FEE_HTLC_TX)) {
-		if (!(channel_flags & CHANNEL_FLAGS_ANNOUNCE_CHANNEL))
-			channel_type_set_scid_alias(state->channel_type);
+		/* Spec says we should use the option_scid_alias variation if we
+		 * want them to *only* use the scid_alias (which we do for unannounced
+		 * channels!).
+		 *
+		 * But:
+		 * 1. We didn't accept this in CLN prior to v23.05.
+		 * 2. LND won't accept that without OPT_ANCHORS_ZERO_FEE_HTLC_TX.
+		 *
+		 * So we keep it off for now, until anchors merge.
+		 */
+		if (channel_type_has(state->channel_type, OPT_ANCHORS_ZERO_FEE_HTLC_TX)) {
+			if (!(channel_flags & CHANNEL_FLAGS_ANNOUNCE_CHANNEL))
+				channel_type_set_scid_alias(state->channel_type);
+		}
 	}
 
 	/* Which feerate do we use?  (We can lowball fees if using anchors!) */
@@ -447,7 +452,22 @@ static u8 *funder_channel_start(struct state *state, u8 channel_flags,
 	 *   `open_channel`, and they are not equal types:
 	 *    - MUST fail the channel.
 	 */
-	if (accept_tlvs->channel_type) {
+
+	/* Simple case: caller specified, don't allow any variants */
+	if (ctype) {
+		if (!accept_tlvs->channel_type) {
+			negotiation_failed(state,
+					   "They replied without a channel_type");
+			return NULL;
+		}
+		if (!featurebits_eq(accept_tlvs->channel_type, state->channel_type->features)) {
+			negotiation_failed(state,
+					   "Return unoffered channel_type: %s",
+					   fmt_featurebits(tmpctx,
+							   accept_tlvs->channel_type));
+			return NULL;
+		}
+	} else if (accept_tlvs->channel_type) {
 		/* Except that v23.05 could set OPT_SCID_ALIAS in reply! */
 		struct channel_type *atype;
 
@@ -569,7 +589,7 @@ static u8 *funder_channel_start(struct state *state, u8 channel_flags,
 		    "We negotiated option_zeroconf, using our minimum_depth=%d",
 		    state->minimum_depth);
 		/* We set this now to show we're zeroconf */
-		if (their_mindepth == 0)
+		if (their_mindepth == 0 && !ctype)
 			channel_type_set_zeroconf(state->channel_type);
 	} else {
 		state->minimum_depth = their_mindepth;
@@ -581,8 +601,8 @@ static u8 *funder_channel_start(struct state *state, u8 channel_flags,
 		       tal_hex(tmpctx, funding_output_script));
 
 	/* Backwards/cross compat hack */
-	if (intuit_scid_alias_type(state, channel_flags,
-				   accept_tlvs->channel_type != NULL)) {
+	if (!ctype && intuit_scid_alias_type(state, channel_flags,
+					     accept_tlvs->channel_type != NULL)) {
 		channel_type_set_scid_alias(state->channel_type);
 	}
 
@@ -1437,6 +1457,7 @@ static u8 *handle_master_in(struct state *state)
 	struct bitcoin_txid funding_txid;
 	u16 funding_txout;
 	u32 nonanchor_feerate, anchor_feerate;
+	struct channel_type *ctype;
 
 	switch (t) {
 	case WIRE_OPENINGD_FUNDER_START:
@@ -1449,9 +1470,11 @@ static u8 *handle_master_in(struct state *state)
 						    &anchor_feerate,
 						    &state->channel_id,
 						    &channel_flags,
-						    &state->reserve))
+						    &state->reserve,
+						    &ctype))
 			master_badmsg(WIRE_OPENINGD_FUNDER_START, msg);
-		msg = funder_channel_start(state, channel_flags, nonanchor_feerate, anchor_feerate);
+		msg = funder_channel_start(state, channel_flags, nonanchor_feerate, anchor_feerate, ctype);
+		tal_free(ctype);
 
 		/* We want to keep openingd alive, since we're not done yet */
 		if (msg)

openingd/openingd_wire.csv

@@ -87,6 +87,7 @@ msgdata,openingd_funder_start,anchor_feerate_per_kw,u32,
 msgdata,openingd_funder_start,temporary_channel_id,channel_id,
 msgdata,openingd_funder_start,channel_flags,u8,
 msgdata,openingd_funder_start,reserve,?amount_sat,
+msgdata,openingd_funder_start,channel_type,?channel_type,
 
 # openingd->master: send back output script for 2-of-2 funding output
 msgtype,openingd_funder_start_reply,6102

tests/test_opening.py

@@ -4,6 +4,7 @@ from pyln.client import RpcError, Millisatoshi
 from utils import (
     only_one, wait_for, sync_blockheight, first_channel_id, calc_lease_fee, check_coin_moves
 )
+from pyln.testing.utils import FUNDAMOUNT
 
 from pathlib import Path
 from pprint import pprint
@@ -2581,3 +2582,56 @@ def test_fundchannel_utxo_too_small(bitcoind, node_factory):
     l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
     with pytest.raises(RpcError, match=r'Could not afford 100000sat using all 0 available UTXOs'):
         l1.rpc.fundchannel(l2.info['id'], 100000, 10000)
+
+
+@unittest.skipIf(TEST_NETWORK != 'regtest', 'elementsd doesnt yet support PSBT features we need')
+def test_opening_explicit_channel_type(node_factory):
+    plugin_path = Path(__file__).parent / "plugins" / "zeroconf-selective.py"
+    l1, l2, l3, l4 = node_factory.get_nodes(4,
+                                            opts=[{'experimental-dual-fund': None,
+                                                   'experimental-anchors': None},
+                                                  {'experimental-anchors': None,
+                                                   'plugin': str(plugin_path),
+                                                   'zeroconf-allow': '0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518'},
+                                                  {'experimental-dual-fund': None,
+                                                   'experimental-anchors': None},
+                                                  {'experimental-anchors': None}])
+
+    l1.fundwallet(FUNDAMOUNT)
+    l1.connect(l2)
+    l1.connect(l3)
+    l1.connect(l4)
+
+    STATIC_REMOTEKEY = 12
+    ANCHORS_OLD = 20
+    ANCHORS_ZERO_FEE_HTLC_TX = 22
+    ZEROCONF = 50
+
+    for zeroconf in ([], [ZEROCONF]):
+        for ctype in ([],
+                      [STATIC_REMOTEKEY],
+                      [ANCHORS_ZERO_FEE_HTLC_TX, STATIC_REMOTEKEY]):
+            l1.rpc.fundchannel_start(l2.info['id'], FUNDAMOUNT,
+                                     channel_type=ctype + zeroconf)
+            l1.rpc.fundchannel_cancel(l2.info['id'])
+            # FIXME: Check type is actually correct!
+
+    # Zeroconf is refused to l4.
+    for ctype in ([],
+                  [STATIC_REMOTEKEY],
+                  [ANCHORS_ZERO_FEE_HTLC_TX, STATIC_REMOTEKEY]):
+        with pytest.raises(RpcError, match=r'not on our allowlist'):
+            l1.rpc.fundchannel_start(l4.info['id'], FUNDAMOUNT,
+                                     channel_type=ctype + [ZEROCONF])
+
+    psbt = l1.rpc.fundpsbt(FUNDAMOUNT - 1000, '253perkw', 250, reserve=0)['psbt']
+    for ctype in ([], [12], [22, 12]):
+        cid = l1.rpc.openchannel_init(l3.info['id'], FUNDAMOUNT - 1000, psbt, channel_type=ctype)['channel_id']
+        l1.rpc.openchannel_abort(cid)
+
+    # Old anchors not supported for new channels
+    with pytest.raises(RpcError, match=r'channel_type not supported'):
+        l1.rpc.fundchannel_start(l2.info['id'], FUNDAMOUNT, channel_type=[STATIC_REMOTEKEY, ANCHORS_OLD])
+
+    with pytest.raises(RpcError, match=r'channel_type not supported'):
+        l1.rpc.openchannel_init(l3.info['id'], FUNDAMOUNT - 1000, psbt, channel_type=[STATIC_REMOTEKEY, ANCHORS_OLD])