bitcoind: work around fundrawtransaction segwit issue.

See https://github.com/sipa/bitcaoin/issues/67

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

bitcoin/tx.c

@@ -195,6 +195,14 @@ u8 *linearize_tx(const tal_t *ctx, const struct bitcoin_tx *tx)
 	return arr;
 }
 
+u8 *linearize_tx_force_extended(const tal_t *ctx,
+				const struct bitcoin_tx *tx)
+{
+	u8 *arr = tal_arr(ctx, u8, 0);
+	add_tx(tx, add_linearize, &arr, true);
+	return arr;
+}
+
 void bitcoin_txid(const struct bitcoin_tx *tx, struct sha256_double *txid)
 {
 	struct sha256_ctx ctx = SHA256_INIT;

bitcoin/tx.h

@@ -46,6 +46,10 @@ void sha256_tx_for_sig(struct sha256_ctx *ctx, const struct bitcoin_tx *tx,
 /* Linear bytes of tx. */
 u8 *linearize_tx(const tal_t *ctx, const struct bitcoin_tx *tx);
 
+/* Force linearization in extended form; useful if 0 inputs. */
+u8 *linearize_tx_force_extended(const tal_t *ctx,
+				const struct bitcoin_tx *tx);
+
 /* Allocate a tx: you just need to fill in inputs and outputs (they're
  * zeroed with inputs' sequence_number set to FFFFFFFF) */
 struct bitcoin_tx *bitcoin_tx(const tal_t *ctx, varint_t input_count,

daemon/bitcoind.c

@@ -519,7 +519,7 @@ void bitcoind_fund_transaction(struct lightningd_state *dstate,
 			       struct peer *peer)
 {
 	struct funding_process *f = tal(peer, struct funding_process);
-	u8 *raw = linearize_tx(dstate, tx_no_inputs);
+	u8 *raw = linearize_tx_force_extended(dstate, tx_no_inputs);
 	char *hex = tal_arr(raw, char, hex_str_size(tal_count(raw)));
 
 	assert(tx_no_inputs->input_count == 0);