Small fixes: dual-funding

common/json_helpers.c

@@ -290,11 +290,13 @@ void json_add_tx(struct json_stream *result,
 
 void json_add_psbt(struct json_stream *stream,
 		   const char *fieldname,
-		   const struct wally_psbt *psbt)
+		   const struct wally_psbt *psbt TAKES)
 {
 	const char *psbt_b64;
 	psbt_b64 = psbt_to_b64(NULL, psbt);
 	json_add_string(stream, fieldname, take(psbt_b64));
+	if (taken(psbt))
+		tal_free(psbt);
 }
 
 void json_add_amount_msat_compat(struct json_stream *result,

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

@@ -92,6 +92,13 @@ def to_satoshi(self) -> Decimal:
         """
         return Decimal(self.millisatoshis) / 1000
 
+    def to_whole_satoshi(self) -> int:
+        """
+        Return an int respresenting the number of satoshis;
+        rounded up to the nearest satoshi
+        """
+        return (self.millisatoshis + 999) // 1000
+
     def to_btc(self) -> Decimal:
         """
         Return a Decimal representing the number of bitcoin.
@@ -1244,7 +1251,7 @@ def unreserveinputs(self, psbt):
         }
         return self.call("unreserveinputs", payload)
 
-    def fundpsbt(self, satoshi, feerate, startweight, minconf=None, reserve=True, locktime=None):
+    def fundpsbt(self, satoshi, feerate, startweight, minconf=None, reserve=True, locktime=None, min_witness_weight=None):
         """
         Create a PSBT with inputs sufficient to give an output of satoshi.
         """
@@ -1255,10 +1262,11 @@ def fundpsbt(self, satoshi, feerate, startweight, minconf=None, reserve=True, lo
             "minconf": minconf,
             "reserve": reserve,
             "locktime": locktime,
+            "min_witness_weight": min_witness_weight,
         }
         return self.call("fundpsbt", payload)
 
-    def utxopsbt(self, satoshi, feerate, startweight, utxos, reserve=True, reservedok=False, locktime=None):
+    def utxopsbt(self, satoshi, feerate, startweight, utxos, reserve=True, reservedok=False, locktime=None, min_witness_weight=None):
         """
         Create a PSBT with given inputs, to give an output of satoshi.
         """
@@ -1270,6 +1278,7 @@ def utxopsbt(self, satoshi, feerate, startweight, utxos, reserve=True, reservedo
             "reserve": reserve,
             "reservedok": reservedok,
             "locktime": locktime,
+            "min_witness_weight": min_witness_weight,
         }
         return self.call("utxopsbt", payload)
 

lightningd/dual_open_control.c

@@ -306,15 +306,16 @@ hook_extract_amount(struct subd *dualopend,
 	return true;
 }
 
-#define CHECK_CHANGES(set, dir) 						\
-	do {		   							\
-	for (size_t i = 0; i < tal_count(set); i++) { 				\
-		ok = psbt_get_serial_id(&set[i].dir.unknowns, &serial_id); 	\
-		assert(ok); 							\
-		if (serial_id % 2 != opener_side)				\
-			return true;						\
-	}									\
-	} while (false)								\
+#define CHECK_CHANGES(set, dir) 					\
+	do {		   						\
+		for (size_t i = 0; i < tal_count(set); i++) { 		\
+			ok = psbt_get_serial_id(&set[i].dir.unknowns,	\
+						&serial_id); 		\
+			assert(ok); 					\
+			if (serial_id % 2 != opener_side)		\
+				return true;				\
+		}							\
+	} while (false)
 
 static bool psbt_side_contribs_changed(struct wally_psbt *orig,
 				       struct wally_psbt *new,

openingd/dualopend.c

@@ -585,7 +585,14 @@ static char *check_balances(const tal_t *ctx,
 				      initiator_weight);
 
 	if (!amount_sat_greater_eq(accepter_diff, accepter_fee)) {
-		return "accepter fee not covered";
+		return tal_fmt(ctx, "accepter fee not covered"
+			       " (need %s > have %s)",
+			       type_to_string(ctx,
+					      struct amount_sat,
+					      &accepter_fee),
+			       type_to_string(ctx,
+					      struct amount_sat,
+					      &accepter_diff));
 	}
 
 	if (!amount_sat_greater_eq(initiator_diff, initiator_fee)) {

tests/plugins/df_accepter.py

@@ -5,8 +5,15 @@
 from pyln.client import Plugin, Millisatoshi
 from pyln.proto import bech32_decode
 from typing import Iterable, List, Optional
-from wallycore import psbt_add_output_at, psbt_from_base64, psbt_to_base64, tx_output_init
-
+from wallycore import (
+    psbt_add_output_at,
+    psbt_find_input_unknown,
+    psbt_from_base64,
+    psbt_get_input_unknown,
+    psbt_get_num_inputs,
+    psbt_to_base64,
+    tx_output_init,
+)
 
 plugin = Plugin()
 
@@ -58,6 +65,26 @@ def find_feerate(best, their_min, their_max, our_min, our_max):
     return our_max
 
 
+def find_inputs(b64_psbt):
+    serial_id_key = bytes.fromhex('fc096c696768746e696e6701')
+    psbt = psbt_from_base64(b64_psbt)
+    input_idxs = []
+
+    for i in range(psbt_get_num_inputs(psbt)):
+        idx = psbt_find_input_unknown(psbt, i, serial_id_key)
+        if idx == 0:
+            continue
+        # returned index is off by one, so 0 can be 'not found'
+        serial_bytes = psbt_get_input_unknown(psbt, i, idx - 1)
+        serial_id = int.from_bytes(serial_bytes, byteorder='big', signed=False)
+
+        # We're the accepter, so our inputs have odd serials
+        if serial_id % 2:
+            input_idxs.append(i)
+
+    return input_idxs
+
+
 @plugin.hook('openchannel2')
 def on_openchannel(openchannel2, plugin, **kwargs):
     # We mirror what the peer does, wrt to funding amount ...
@@ -79,16 +106,17 @@ def on_openchannel(openchannel2, plugin, **kwargs):
     funding = plugin.rpc.fundpsbt(amount,
                                   '{}perkw'.format(feerate),
                                   0, reserve=True,
-                                  locktime=locktime)
+                                  locktime=locktime,
+                                  min_witness_weight=110)
     psbt_obj = psbt_from_base64(funding['psbt'])
 
     excess = Millisatoshi(funding['excess_msat'])
-    change_cost = Millisatoshi(124 * feerate // 1000 * 1000)
+    change_cost = Millisatoshi(124 * feerate)
     dust_limit = Millisatoshi(253 * 1000)
     if excess > (dust_limit + change_cost):
         addr = plugin.rpc.newaddr()['bech32']
         change = excess - change_cost
-        output = tx_output_init(int(change.to_satoshi()), get_script(addr))
+        output = tx_output_init(change.to_whole_satoshi(), get_script(addr))
         psbt_add_output_at(psbt_obj, 0, 0, output)
 
     return {'result': 'continue', 'psbt': psbt_to_base64(psbt_obj, 0),
@@ -108,12 +136,13 @@ def on_tx_sign(openchannel2_sign, plugin, **kwargs):
     psbt = openchannel2_sign['psbt']
 
     # We only sign the ones with our parity of a serial_id
-    # FIXME: find the inputs with an odd-serial, these are ours
-    # the key for a serial_id ::
-    # our_inputs = [1]
+    input_idxs = find_inputs(psbt)
+    if len(input_idxs) > 0:
+        final_psbt = plugin.rpc.signpsbt(psbt, signonly=input_idxs)['signed_psbt']
+    else:
+        final_psbt = psbt
 
-    signed_psbt = plugin.rpc.signpsbt(psbt)['signed_psbt']
-    return {'result': 'continue', 'psbt': signed_psbt}
+    return {'result': 'continue', 'psbt': final_psbt}
 
 
 plugin.run()