common: make funding_tx and withdraw_tx share UTXO code.

They both do the same thing: convert utxos into tx inputs.  Share code.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

closingd/Makefile

@@ -55,6 +55,7 @@ CLOSINGD_COMMON_OBJS :=				\
 	common/gen_peer_status_wire.o		\
 	common/gen_status_wire.o		\
 	common/htlc_wire.o			\
+	common/key_derive.o			\
 	common/memleak.o			\
 	common/msg_queue.o			\
 	common/peer_billboard.o			\

common/funding_tx.c

@@ -3,7 +3,6 @@
 #include <bitcoin/script.h>
 #include <bitcoin/tx.h>
 #include <ccan/ptrint/ptrint.h>
-#include <common/key_derive.h>
 #include <common/permute_tx.h>
 #include <common/utxo.h>
 
@@ -21,23 +20,10 @@ struct bitcoin_tx *funding_tx(const tal_t *ctx,
 			      const struct pubkey *changekey,
 			      const struct ext_key *bip32_base)
 {
-	struct bitcoin_tx *tx = bitcoin_tx(ctx, tal_count(utxomap),
-					   change_satoshis ? 2 : 1);
 	u8 *wscript;
-	size_t i;
+	struct bitcoin_tx *tx;
 
-	for (i = 0; i < tal_count(utxomap); i++) {
-		tx->input[i].txid = utxomap[i]->txid;
-		tx->input[i].index = utxomap[i]->outnum;
-		tx->input[i].amount = tal_dup(tx, u64, &utxomap[i]->amount);
-		if (utxomap[i]->is_p2sh && bip32_base) {
-			struct pubkey key;
-
-			bip32_pubkey(bip32_base, &key, utxomap[i]->keyindex);
-			tx->input[i].script
-				= bitcoin_scriptsig_p2sh_p2wpkh(tx, &key);
-		}
-	}
+	tx = tx_spending_utxos(ctx, utxomap, bip32_base, change_satoshis != 0);
 
 	tx->output[0].amount = funding_satoshis;
 	wscript = bitcoin_redeem_2of2(tx, local_fundingkey, remote_fundingkey);

common/test/run-funding_tx.c

@@ -14,6 +14,41 @@
   #include "../key_derive.c"
   #include "../type_to_string.c"
   #include "../permute_tx.c"
+  #include "../utxo.c"
+
+/* AUTOGENERATED MOCKS START */
+/* Generated stub for fromwire_bitcoin_txid */
+void fromwire_bitcoin_txid(const u8 **cursor UNNEEDED, size_t *max UNNEEDED,
+			   struct bitcoin_txid *txid UNNEEDED)
+{ fprintf(stderr, "fromwire_bitcoin_txid called!\n"); abort(); }
+/* Generated stub for fromwire_bool */
+bool fromwire_bool(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
+{ fprintf(stderr, "fromwire_bool called!\n"); abort(); }
+/* Generated stub for fromwire_pubkey */
+void fromwire_pubkey(const u8 **cursor UNNEEDED, size_t *max UNNEEDED, struct pubkey *pubkey UNNEEDED)
+{ fprintf(stderr, "fromwire_pubkey called!\n"); abort(); }
+/* Generated stub for fromwire_u32 */
+u32 fromwire_u32(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
+{ fprintf(stderr, "fromwire_u32 called!\n"); abort(); }
+/* Generated stub for fromwire_u64 */
+u64 fromwire_u64(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
+{ fprintf(stderr, "fromwire_u64 called!\n"); abort(); }
+/* Generated stub for towire_bitcoin_txid */
+void towire_bitcoin_txid(u8 **pptr UNNEEDED, const struct bitcoin_txid *txid UNNEEDED)
+{ fprintf(stderr, "towire_bitcoin_txid called!\n"); abort(); }
+/* Generated stub for towire_bool */
+void towire_bool(u8 **pptr UNNEEDED, bool v UNNEEDED)
+{ fprintf(stderr, "towire_bool called!\n"); abort(); }
+/* Generated stub for towire_pubkey */
+void towire_pubkey(u8 **pptr UNNEEDED, const struct pubkey *pubkey UNNEEDED)
+{ fprintf(stderr, "towire_pubkey called!\n"); abort(); }
+/* Generated stub for towire_u32 */
+void towire_u32(u8 **pptr UNNEEDED, u32 v UNNEEDED)
+{ fprintf(stderr, "towire_u32 called!\n"); abort(); }
+/* Generated stub for towire_u64 */
+void towire_u64(u8 **pptr UNNEEDED, u64 v UNNEEDED)
+{ fprintf(stderr, "towire_u64 called!\n"); abort(); }
+/* AUTOGENERATED MOCKS END */
 
 #if 0
 static struct sha256 sha256_from_hex(const char *hex)

common/utxo.c

@@ -1,3 +1,5 @@
+#include <bitcoin/script.h>
+#include <common/key_derive.h>
 #include <common/utxo.h>
 #include <wire/wire.h>
 
@@ -39,3 +41,26 @@ struct utxo *fromwire_utxo(const tal_t *ctx, const u8 **ptr, size_t *max)
 	}
 	return utxo;
 }
+
+struct bitcoin_tx *tx_spending_utxos(const tal_t *ctx,
+				     const struct utxo **utxos,
+				     const struct ext_key *bip32_base,
+				     bool add_change_output)
+{
+	struct bitcoin_tx *tx =
+	    bitcoin_tx(ctx, tal_count(utxos), add_change_output ? 2 : 1);
+
+	for (size_t i = 0; i < tal_count(utxos); i++) {
+		tx->input[i].txid = utxos[i]->txid;
+		tx->input[i].index = utxos[i]->outnum;
+		tx->input[i].amount = tal_dup(tx, u64, &utxos[i]->amount);
+		if (utxos[i]->is_p2sh && bip32_base) {
+			struct pubkey key;
+			bip32_pubkey(bip32_base, &key, utxos[i]->keyindex);
+			tx->input[i].script =
+				bitcoin_scriptsig_p2sh_p2wpkh(tx, &key);
+		}
+	}
+
+	return tx;
+}

common/utxo.h

@@ -8,6 +8,8 @@
 #include <ccan/tal/tal.h>
 #include <stdbool.h>
 
+struct ext_key;
+
 /* Information needed for their_unilateral/to-us outputs */
 struct unilateral_close_info {
 	u64 channel_id;
@@ -36,4 +38,11 @@ struct utxo {
 
 void towire_utxo(u8 **pptr, const struct utxo *utxo);
 struct utxo *fromwire_utxo(const tal_t *ctx, const u8 **ptr, size_t *max);
+
+/* Create a tx, and populate inputs from utxos */
+struct bitcoin_tx *tx_spending_utxos(const tal_t *ctx,
+				     const struct utxo **utxos,
+				     const struct ext_key *bip32_base,
+				     bool add_change_output);
+
 #endif /* LIGHTNING_COMMON_UTXO_H */

common/withdraw_tx.c

@@ -2,7 +2,6 @@
 #include <bitcoin/pubkey.h>
 #include <bitcoin/script.h>
 #include <ccan/ptrint/ptrint.h>
-#include <common/key_derive.h>
 #include <common/permute_tx.h>
 #include <common/utxo.h>
 #include <string.h>
@@ -16,19 +15,10 @@ struct bitcoin_tx *withdraw_tx(const tal_t *ctx,
 			       const u64 changesat,
 			       const struct ext_key *bip32_base)
 {
-	struct bitcoin_tx *tx =
-	    bitcoin_tx(ctx, tal_count(utxos), changesat ? 2 : 1);
-	for (size_t i = 0; i < tal_count(utxos); i++) {
-		tx->input[i].txid = utxos[i]->txid;
-		tx->input[i].index = utxos[i]->outnum;
-		tx->input[i].amount = tal_dup(tx, u64, &utxos[i]->amount);
-		if (utxos[i]->is_p2sh && bip32_base) {
-			struct pubkey key;
-			bip32_pubkey(bip32_base, &key, utxos[i]->keyindex);
-			tx->input[i].script =
-				bitcoin_scriptsig_p2sh_p2wpkh(tx, &key);
-		}
-	}
+	struct bitcoin_tx *tx;
+
+	tx = tx_spending_utxos(ctx, utxos, bip32_base, changesat != 0);
+
 	tx->output[0].amount = withdraw_amount;
 	tx->output[0].script = destination;
 

connectd/Makefile

@@ -49,6 +49,7 @@ CONNECTD_COMMON_OBJS :=				\
 	common/dev_disconnect.o			\
 	common/features.o			\
 	common/gen_status_wire.o		\
+	common/key_derive.o			\
 	common/memleak.o			\
 	common/msg_queue.o			\
 	common/pseudorand.o			\

gossipd/Makefile

@@ -49,6 +49,7 @@ GOSSIPD_COMMON_OBJS :=				\
 	common/dev_disconnect.o			\
 	common/features.o			\
 	common/gen_status_wire.o		\
+	common/key_derive.o			\
 	common/memleak.o			\
 	common/msg_queue.o			\
 	common/ping.o				\

lightningd/test/Makefile

@@ -18,6 +18,7 @@ LIGHTNINGD_TEST_COMMON_OBJS :=			\
 	common/memleak.o			\
 	common/msg_queue.o			\
 	common/utils.o				\
+	common/utxo.o				\
 	common/type_to_string.o			\
 	common/permute_tx.o