wallet: Allow limiting the selection by confirmation height

This allows us to specify that an output must have been confirmed before the
given maximum height. This allows us to specify a minimum number of
confirmations for an output to be selected.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

common/wallet_tx.c

@@ -57,7 +57,8 @@ static struct command_result *check_amount(const struct wallet_tx *wtx,
 
 struct command_result *wtx_select_utxos(struct wallet_tx *tx,
 					u32 fee_rate_per_kw,
-					size_t out_len)
+					size_t out_len,
+					u32 maxheight)
 {
 	struct command_result *res;
 	struct amount_sat fee_estimate;
@@ -66,6 +67,7 @@ struct command_result *wtx_select_utxos(struct wallet_tx *tx,
 		struct amount_sat amount;
 		tx->utxos = wallet_select_all(tx->cmd, tx->cmd->ld->wallet,
 					      fee_rate_per_kw, out_len,
+					      maxheight,
 					      &amount,
 					      &fee_estimate);
 		res = check_amount(tx, amount);
@@ -88,6 +90,7 @@ struct command_result *wtx_select_utxos(struct wallet_tx *tx,
 	tx->utxos = wallet_select_coins(tx->cmd, tx->cmd->ld->wallet,
 					tx->amount,
 					fee_rate_per_kw, out_len,
+					maxheight,
 					&fee_estimate, &tx->change);
 	res = check_amount(tx, tx->amount);
 	if (res)

common/wallet_tx.h

@@ -29,5 +29,6 @@ struct command_result *param_wtx(struct command *cmd,
 
 struct command_result *wtx_select_utxos(struct wallet_tx *tx,
 					u32 fee_rate_per_kw,
-					size_t out_len);
+					size_t out_len,
+					u32 maxheight);
 #endif /* LIGHTNING_COMMON_WALLET_TX_H */

lightningd/opening_control.c

@@ -891,7 +891,7 @@ static struct command_result *json_fund_channel(struct command *cmd,
 	}
 
 	res = wtx_select_utxos(&fc->wtx, *feerate_per_kw,
-			       BITCOIN_SCRIPTPUBKEY_P2WSH_LEN);
+			       BITCOIN_SCRIPTPUBKEY_P2WSH_LEN, 0);
 	if (res)
 		return res;
 

wallet/test/run-wallet.c

@@ -711,7 +711,9 @@ static bool test_wallet_outputs(struct lightningd *ld, const tal_t *ctx)
 		  "wallet_add_utxo with close_info");
 
 	/* Now select them */
-	utxos = wallet_select_coins(w, w, AMOUNT_SAT(2), 0, 21, &fee_estimate, &change_satoshis);
+	utxos = wallet_select_coins(w, w, AMOUNT_SAT(2), 0, 21,
+				    0 /* no confirmations required */,
+				    &fee_estimate, &change_satoshis);
 	CHECK(utxos && tal_count(utxos) == 2);
 
 	u = *utxos[1];

wallet/wallet.c

@@ -254,6 +254,7 @@ static const struct utxo **wallet_select(const tal_t *ctx, struct wallet *w,
 					 const u32 feerate_per_kw,
 					 size_t outscriptlen,
 					 bool may_have_change,
+					 u32 maxheight,
 					 struct amount_sat *satoshi_in,
 					 struct amount_sat *fee_estimate)
 {
@@ -283,6 +284,13 @@ static const struct utxo **wallet_select(const tal_t *ctx, struct wallet *w,
 		struct amount_sat needed;
 		struct utxo *u = tal_steal(utxos, available[i]);
 
+		/* If we require confirmations check that we have a
+		 * confirmation height and that it is below the required
+		 * maxheight (current_height - minconf */
+		if (maxheight != 0 &&
+		    (!u->blockheight || *u->blockheight > maxheight))
+			continue;
+
 		tal_arr_expand(&utxos, u);
 
 		if (!wallet_update_output_status(
@@ -332,6 +340,7 @@ const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
 					struct amount_sat sat,
 					const u32 feerate_per_kw,
 					size_t outscriptlen,
+					u32 maxheight,
 					struct amount_sat *fee_estimate,
 					struct amount_sat *change)
 {
@@ -339,7 +348,7 @@ const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
 	const struct utxo **utxo;
 
 	utxo = wallet_select(ctx, w, sat, feerate_per_kw,
-			     outscriptlen, true,
+			     outscriptlen, true, maxheight,
 			     &satoshi_in, fee_estimate);
 
 	/* Couldn't afford it? */
@@ -353,6 +362,7 @@ const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
 const struct utxo **wallet_select_all(const tal_t *ctx, struct wallet *w,
 				      const u32 feerate_per_kw,
 				      size_t outscriptlen,
+				      u32 maxheight,
 				      struct amount_sat *value,
 				      struct amount_sat *fee_estimate)
 {
@@ -361,7 +371,7 @@ const struct utxo **wallet_select_all(const tal_t *ctx, struct wallet *w,
 
 	/* Huge value, but won't overflow on addition */
 	utxo = wallet_select(ctx, w, AMOUNT_SAT(1ULL << 56), feerate_per_kw,
-			     outscriptlen, false,
+			     outscriptlen, false, maxheight,
 			     &satoshi_in, fee_estimate);
 
 	/* Can't afford fees? */

wallet/wallet.h

@@ -319,12 +319,14 @@ const struct utxo **wallet_select_coins(const tal_t *ctx, struct wallet *w,
 					struct amount_sat value,
 					const u32 feerate_per_kw,
 					size_t outscriptlen,
+					u32 maxheight,
 					struct amount_sat *fee_estimate,
 					struct amount_sat *change_satoshi);
 
 const struct utxo **wallet_select_all(const tal_t *ctx, struct wallet *w,
 				      const u32 feerate_per_kw,
 				      size_t outscriptlen,
+				      u32 maxheight,
 				      struct amount_sat *sat,
 				      struct amount_sat *fee_estimate);
 

wallet/walletrpc.c

@@ -139,7 +139,7 @@ static struct command_result *json_withdraw(struct command *cmd,
 	}
 
 	res = wtx_select_utxos(&withdraw->wtx, *feerate_per_kw,
-			       tal_count(withdraw->destination));
+			       tal_count(withdraw->destination), 0);
 	if (res)
 		return res;