liquidity-ad: pipe request_amt all the way out to fundchannel

Changelog-Added: JSON-RPC: `fundchannel` now takes optional `request_amt` parameter

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

@@ -693,7 +693,7 @@ class LightningRpc(UnixDomainSocketRpc):
         }
         return self.call("feerates", payload)
 
-    def fundchannel(self, node_id, amount, feerate=None, announce=True, minconf=None, utxos=None, push_msat=None, close_to=None):
+    def fundchannel(self, node_id, amount, feerate=None, announce=True, minconf=None, utxos=None, push_msat=None, close_to=None, request_amt=None):
         """
         Fund channel with {id} using {amount} satoshis with feerate
         of {feerate} (uses default feerate if unset).
@@ -702,6 +702,10 @@ class LightningRpc(UnixDomainSocketRpc):
         If {utxos} is specified (as a list of 'txid:vout' strings),
         fund a channel from these specifics utxos.
         {close_to} is a valid Bitcoin address.
+
+        {request_amt} is the lease amount to request from the peer. Only
+        valid if peer is advertising a liquidity ad + supports v2 channel opens
+        (dual-funding)
         """
         payload = {
             "id": node_id,
@@ -712,6 +716,7 @@ class LightningRpc(UnixDomainSocketRpc):
             "utxos": utxos,
             "push_msat": push_msat,
             "close_to": close_to,
+            "request_amt": request_amt,
         }
         return self.call("fundchannel", payload)
 

doc/lightning-fundchannel.7

@@ -72,6 +72,11 @@ on close\. Only valid if both peers have negotiated \fBoption_upfront_shutdown_s
 Returns \fBclose_to\fR set to closing script iff is negotiated\.
 
 
+\fIrequest_amt\fR is an amount of liquidity you'd like to lease from the peer\.
+If peer supports \fBoption_will_fund\fR, indicates to them to include this
+much liquidity into the channel\.
+
+
 This example shows how to use lightning-cli to open new channel with peer 03f\.\.\.fc1 from one whole utxo bcc1\.\.\.39c:0
 (you can use \fBlistfunds\fR command to get txid and vout):
 
@@ -80,7 +85,6 @@ This example shows how to use lightning-cli to open new channel with peer 03f\.\
 lightning-cli -k fundchannel id=03f...fc1 amount=all feerate=normal utxos='["bcc1...39c:0"]'
 
 
-
 .RE
 
 .fi
@@ -130,4 +134,4 @@ channel parameters (funding limits, channel reserves, fees, etc\.)\.
 
 Main web site: \fIhttps://github.com/ElementsProject/lightning\fR
 
-\" SHA256STAMP:d25fc36b745b6f58556f7f4b06f23ff83b466d4a00911f7ffdc9d86572902954
+\" SHA256STAMP:c7cd9291a08e66e41b24d0045c313ac1e3dabcb4579ab5fe132aad8d1ecbb640

doc/lightning-fundchannel.7.md

@@ -64,12 +64,16 @@ unrecoverable once pushed.
 on close. Only valid if both peers have negotiated `option_upfront_shutdown_script`.
 Returns `close_to` set to closing script iff is negotiated.
 
+*request_amt* is an amount of liquidity you'd like to lease from the peer.
+If peer supports `option_will_fund`, indicates to them to include this
+much liquidity into the channel.
+
+
 This example shows how to use lightning-cli to open new channel with peer 03f...fc1 from one whole utxo bcc1...39c:0
 (you can use **listfunds** command to get txid and vout):
 
 	lightning-cli -k fundchannel id=03f...fc1 amount=all feerate=normal utxos='["bcc1...39c:0"]'
 
-
 RETURN VALUE
 ------------
 

doc/lightning-multifundchannel.7

@@ -58,6 +58,10 @@ out of this\.
 on close\. Only valid if both peers have negotiated
 \fBoption_upfront_shutdown_script\fR\.  Returns \fBclose_to\fR set to
 closing script iff is negotiated\.
+.IP \[bu]
+\fIrequest_amt\fR is the amount of liquidity you'd like to lease from peer\.
+If peer supports \fBoption_will_fund\fR, indicates to them to include this
+much liquidity into the channel\.
 
 .RE
 
@@ -204,4 +208,4 @@ ZmnSCPxj \fI<ZmnSCPxj@protonmail.com\fR> is mainly responsible\.
 
 Main web site: \fIhttps://github.com/ElementsProject/lightning\fR
 
-\" SHA256STAMP:86b05635f6d0d55dc3771779237bf1046b52f8cd290f16cccc5656cb94f2863a
+\" SHA256STAMP:fa55ac01a568d6b816641ddbfa3c9cccf437dea06df5ec84747f7ef02db6d47e

doc/lightning-multifundchannel.7.md

@@ -51,6 +51,9 @@ Readiness is indicated by **listpeers** reporting a *state* of
   on close. Only valid if both peers have negotiated
   `option_upfront_shutdown_script`.  Returns `close_to` set to
   closing script iff is negotiated.
+* *request_amt* is the amount of liquidity you'd like to lease from peer.
+If peer supports `option_will_fund`, indicates to them to include this
+much liquidity into the channel.
 
 There must be at least one entry in *destinations*;
 it cannot be an empty array.

plugins/spender/fundchannel.c

@@ -42,6 +42,7 @@ json_fundchannel(struct command *cmd,
 	const jsmntok_t *utxos;
 	const jsmntok_t *push_msat;
 	const jsmntok_t *close_to;
+	const jsmntok_t *request_amt;
 
 	struct out_req *req;
 
@@ -54,6 +55,7 @@ json_fundchannel(struct command *cmd,
 		   p_opt("utxos", param_tok, &utxos),
 		   p_opt("push_msat", param_tok, &push_msat),
 		   p_opt("close_to", param_tok, &close_to),
+		   p_opt("request_amt", param_tok, &request_amt),
 		   NULL))
 		return command_param_failed();
 
@@ -71,6 +73,8 @@ json_fundchannel(struct command *cmd,
 		json_add_tok(req->js, "push_msat", push_msat, buf);
 	if (close_to)
 		json_add_tok(req->js, "close_to", close_to, buf);
+	if (request_amt)
+		json_add_tok(req->js, "request_amt", request_amt, buf);
 	json_object_end(req->js);
 	json_array_end(req->js);
 	if (feerate)

plugins/spender/multifundchannel.c

@@ -1813,7 +1813,7 @@ param_destinations_array(struct command *cmd, const char *name,
 		struct multifundchannel_destination *dest;
 		const char *id;
 		char *addrhint;
-		struct amount_sat *amount;
+		struct amount_sat *amount, *request_amt;
 		bool *announce;
 		struct amount_msat *push_msat;
 
@@ -1830,6 +1830,8 @@ param_destinations_array(struct command *cmd, const char *name,
 			    * passed in to fundchannel_start) if invalid*/
 			   p_opt("close_to", param_string,
 				 &dest->close_to_str),
+			   p_opt_def("request_amt", param_sat, &request_amt,
+				     AMOUNT_SAT(0)),
 			   NULL))
 			return command_param_failed();
 
@@ -1864,6 +1866,7 @@ param_destinations_array(struct command *cmd, const char *name,
 		dest->psbt = NULL;
 		dest->updated_psbt = NULL;
 		dest->protocol = FUND_CHANNEL;
+		dest->request_amt = *request_amt;
 
 		/* Only one destination can have "all" indicator.  */
 		if (dest->all) {

plugins/spender/multifundchannel.h

@@ -143,6 +143,9 @@ struct multifundchannel_destination {
 
 	/* serial of the funding output for this channel (OPEN_CHANNEL) */
 	u64 funding_serial;
+
+	/* amount to request peer to lease (OPEN_CHANNEL) */
+	struct amount_sat request_amt;
 };
 
 

plugins/spender/openchannel.c

@@ -1025,6 +1025,11 @@ openchannel_init_dest(struct multifundchannel_destination *dest)
 			   type_to_string(tmpctx, struct amount_msat,
 					  &dest->push_msat));
 
+	/* Request some sats from the peer! */
+	if (amount_sat_greater(dest->request_amt, AMOUNT_SAT(0)))
+		json_add_string(req->js, "request_amt",
+				fmt_amount_sat(tmpctx, dest->request_amt));
+
 	return send_outreq(cmd->plugin, req);
 }