core-lightning/common/withdraw_tx.c
Christian Decker 42a63e4416 tx: Strengthen transaction construction checks
We roll the `elements_add_fee_output` function and the cropping of
overallocated arrays into the `bitcoin_tx_finalize` function. This is supposed
to be the final cleanup and compaction step before a tx can be sent to bitcoin
or passed off to other daemons.

This is the cleanup promised in #3491
2020-03-24 09:52:33 +10:30

61 lines
1.6 KiB
C

#include "withdraw_tx.h"
#include <assert.h>
#include <bitcoin/pubkey.h>
#include <bitcoin/script.h>
#include <ccan/ptrint/ptrint.h>
#include <common/permute_tx.h>
#include <common/utils.h>
#include <common/utxo.h>
#include <string.h>
#include <wally_bip32.h>
struct bitcoin_tx *withdraw_tx(const tal_t *ctx,
const struct chainparams *chainparams,
const struct utxo **utxos,
struct bitcoin_tx_output **outputs,
const struct pubkey *changekey,
struct amount_sat change,
const struct ext_key *bip32_base,
int *change_outnum, u32 nlocktime)
{
struct bitcoin_tx *tx;
int output_count;
tx = tx_spending_utxos(ctx, chainparams, utxos, bip32_base,
!amount_sat_eq(change, AMOUNT_SAT(0)),
tal_count(outputs), nlocktime,
BITCOIN_TX_DEFAULT_SEQUENCE - 1);
output_count = bitcoin_tx_add_multi_outputs(tx, outputs);
assert(output_count == tal_count(outputs));
if (!amount_sat_eq(change, AMOUNT_SAT(0))) {
/* Add one to the output_count, for the change */
output_count++;
const void *map[output_count];
for (size_t i = 0; i < output_count; i++)
map[i] = int2ptr(i);
bitcoin_tx_add_output(tx, scriptpubkey_p2wpkh(tmpctx, changekey),
change);
assert(tx->wtx->num_outputs == output_count);
permute_outputs(tx, NULL, map);
/* The change is the last output added, so the last position
* in the map */
if (change_outnum)
*change_outnum = ptr2int(map[output_count - 1]);
} else if (change_outnum)
*change_outnum = -1;
permute_inputs(tx, (const void **)utxos);
bitcoin_tx_finalize(tx);
assert(bitcoin_tx_check(tx));
return tx;
}