fundpsbt: let caller specify locktime.

Required for dual funding where the opener sets it. Changelog-Added: JSON-RPC: fundpsbt takes a new `locktime` parameter Signed-off-by: Rusty Russell <[email protected]>
ElementsProject · Aug 18, 2020 · 7e4b204 · 7e4b204
1 parent 6371a49
commit 7e4b204
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Showing 4 changed files with 21 additions and 9 deletions.
diff --git a/contrib/pyln-client/pyln/client/lightning.py b/contrib/pyln-client/pyln/client/lightning.py
@@ -1126,7 +1126,7 @@ def unreserveinputs(self, psbt):
         }
         return self.call("unreserveinputs", payload)
 
-    def fundpsbt(self, satoshi, feerate, startweight, minconf=None, reserve=True):
+    def fundpsbt(self, satoshi, feerate, startweight, minconf=None, reserve=True, locktime=None):
         """
         Create a PSBT with inputs sufficient to give an output of satoshi.
         """
@@ -1136,6 +1136,7 @@ def fundpsbt(self, satoshi, feerate, startweight, minconf=None, reserve=True):
             "startweight": startweight,
             "minconf": minconf,
             "reserve": reserve,
+            "locktime": locktime,
         }
         return self.call("fundpsbt", payload)
 

diff --git a/doc/lightning-fundpsbt.7 b/doc/lightning-fundpsbt.7
diff --git a/doc/lightning-fundpsbt.7.md b/doc/lightning-fundpsbt.7.md
@@ -4,7 +4,7 @@ lightning-fundpsbt -- Command to populate PSBT inputs from the wallet
 SYNOPSIS
 --------
 
-**fundpsbt** *satoshi* *feerate* *startweight* \[*minconf*\] \[*reserve*\]
+**fundpsbt** *satoshi* *feerate* *startweight* \[*minconf*\] \[*reserve*\] \[*locktime*\]
 
 DESCRIPTION
 -----------
@@ -36,6 +36,9 @@ outputs should have. Default is 1.
 *reserve* is a boolean: if true (the default), then *reserveinputs* is
 called (successfully, with *exclusive* true) on the returned PSBT.
 
+*locktime* is an optional locktime: if not set, it is set to a recent
+block height.
+
 EXAMPLE USAGE
 -------------
 

diff --git a/wallet/reservation.c b/wallet/reservation.c
@@ -219,7 +219,7 @@ static struct command_result *json_fundpsbt(struct command *cmd,
 	u32 *minconf, *weight;
 	struct amount_sat *amount, input, diff;
 	bool all, *reserve;
-	u32 locktime, maxheight, current_height;
+	u32 *locktime, maxheight, current_height;
 	struct bitcoin_tx *tx;
 
 	if (!param(cmd, buffer, params,
@@ -228,6 +228,7 @@ static struct command_result *json_fundpsbt(struct command *cmd,
 		   p_req("startweight", param_number, &weight),
 		   p_opt_def("minconf", param_number, &minconf, 1),
 		   p_opt_def("reserve", param_bool, &reserve, true),
+		   p_opt("locktime", param_u32, &locktime),
 		   NULL))
 		return command_param_failed();
 
@@ -303,18 +304,21 @@ static struct command_result *json_fundpsbt(struct command *cmd,
 	 *   0xFFFFFFFD by default. Other wallets are likely to implement
 	 *   this too).
 	 */
-	locktime = current_height;
+	if (!locktime) {
+		locktime = tal(cmd, u32);
+		*locktime = current_height;
 
-	/* Eventually fuzz it too. */
-	if (locktime > 100 && pseudorand(10) == 0)
-		locktime -= pseudorand(100);
+		/* Eventually fuzz it too. */
+		if (*locktime > 100 && pseudorand(10) == 0)
+			*locktime -= pseudorand(100);
+	}
 
 	/* FIXME: tx_spending_utxos does more than we need, but there
 	 * are other users right now. */
 	tx = tx_spending_utxos(cmd, chainparams,
 			       cast_const2(const struct utxo **, utxos),
 			       cmd->ld->wallet->bip32_base,
-			       false, 0, locktime,
+			       false, 0, *locktime,
 			       BITCOIN_TX_RBF_SEQUENCE);
 
 	response = json_stream_success(cmd);