size_t measure_tx_cost(const struct bitcoin_tx *tx)
{
size_t non_witness_len = 0, witness_len = 0;
add_tx(tx, add_measure, &non_witness_len, false);
if (uses_witness(tx))
add_witnesses(tx, add_measure, &witness_len);
/* Witness bytes only add 1/4 of normal bytes, for cost. */
return non_witness_len * 4 + witness_len;
}
static void add_tx(const struct bitcoin_tx *tx,
void (*add)(const void *, size_t, void *), void *addp,
bool extended)
{
varint_t i;
u8 flag = 0;
add_le32(tx->version, add, addp);
if (extended) {
u8 marker;
/* BIP 144 */
/* marker char Must be zero */
/* flag char Must be nonzero */
marker = 0;
add(&marker, 1, addp);
/* BIP 141: The flag MUST be a 1-byte non-zero
* value. Currently, 0x01 MUST be used.
*
* BUT: Current segwit4 branch breaks fundrawtransaction;
* it sees 0 inputs and thinks it's extended format.
* Make it really an extended format, but without
* witness. */
if (uses_witness(tx))
flag = SEGREGATED_WITNESS_FLAG;
add(&flag, 1, addp);
}
add_varint(tx->input_count, add, addp);
for (i = 0; i < tx->input_count; i++)
add_tx_input(&tx->input[i], add, addp);
add_varint(tx->output_count, add, addp);
for (i = 0; i < tx->output_count; i++)
add_tx_output(&tx->output[i], add, addp);
if (flag & SEGREGATED_WITNESS_FLAG)
add_witnesses(tx, add, addp);
add_le32(tx->lock_time, add, addp);
}
static void push_tx(const struct bitcoin_tx *tx,
void (*push)(const void *, size_t, void *), void *pushp,
bool bip144)
{
varint_t i;
u8 flag = 0;
push_le32(tx->version, push, pushp);
if (bip144 && uses_witness(tx))
flag |= SEGREGATED_WITNESS_FLAG;
/* BIP 141: The flag MUST be a 1-byte non-zero value. */
/* ie. if no flags set, we fallback to pre-BIP144-style */
if (flag) {
u8 marker = 0;
/* BIP 144 */
/* marker char Must be zero */
/* flag char Must be nonzero */
push(&marker, 1, pushp);
push(&flag, 1, pushp);
}
push_varint(tal_count(tx->input), push, pushp);
for (i = 0; i < tal_count(tx->input); i++)
push_tx_input(&tx->input[i], push, pushp);
push_varint(tal_count(tx->output), push, pushp);
for (i = 0; i < tal_count(tx->output); i++)
push_tx_output(&tx->output[i], push, pushp);
if (flag & SEGREGATED_WITNESS_FLAG)
push_witnesses(tx, push, pushp);
push_le32(tx->lock_time, push, pushp);
}
u8 *linearize_tx(const tal_t *ctx, const struct bitcoin_tx *tx)
{
u8 *arr = tal_arr(ctx, u8, 0);
add_tx(tx, add_linearize, &arr, uses_witness(tx));
return arr;
}
