core-lightning/common/funding_tx.c
darosior 273029f244 wallet: set nLockTime to the tip for withdrawal transactions
This sets the nLockTime to the tip (and accordingly each input's nSequence to
0xfffffffe) for withdrawal transactions.

Even if the anti fee-sniping argument might not be valid until some time yet,
this makes our regular wallet transactions far less distinguishable from
bitcoind's ones since it now defaults to using native Segwit transactions
(like us). Moreover other wallets are likely to implement this (if they
haven't already).

Changelog-Added: wallet: withdrawal transactions now sets nlocktime to the current tip.
2020-02-03 00:45:27 +00:00

57 lines
1.5 KiB
C

#include "funding_tx.h"
#include <assert.h>
#include <bitcoin/pubkey.h>
#include <bitcoin/script.h>
#include <bitcoin/tx.h>
#include <ccan/ptrint/ptrint.h>
#include <common/permute_tx.h>
#include <common/utxo.h>
#ifndef SUPERVERBOSE
#define SUPERVERBOSE(...)
#endif
struct bitcoin_tx *funding_tx(const tal_t *ctx,
const struct chainparams *chainparams,
u16 *outnum,
const struct utxo **utxomap,
struct amount_sat funding,
const struct pubkey *local_fundingkey,
const struct pubkey *remote_fundingkey,
struct amount_sat change,
const struct pubkey *changekey,
const struct ext_key *bip32_base)
{
u8 *wscript;
struct bitcoin_tx *tx;
bool has_change = !amount_sat_eq(change, AMOUNT_SAT(0));
tx = tx_spending_utxos(ctx, chainparams, utxomap, bip32_base,
has_change, 1, 0, BITCOIN_TX_DEFAULT_SEQUENCE);
wscript = bitcoin_redeem_2of2(tx, local_fundingkey, remote_fundingkey);
SUPERVERBOSE("# funding witness script = %s\n",
tal_hex(wscript, wscript));
bitcoin_tx_add_output(tx, scriptpubkey_p2wsh(tx, wscript), funding);
tal_free(wscript);
if (has_change) {
const void *map[2];
map[0] = int2ptr(0);
map[1] = int2ptr(1);
bitcoin_tx_add_output(tx, scriptpubkey_p2wpkh(tx, changekey),
change);
permute_outputs(tx, NULL, map);
*outnum = (map[0] == int2ptr(0) ? 0 : 1);
} else {
*outnum = 0;
}
permute_inputs(tx, (const void **)utxomap);
elements_tx_add_fee_output(tx);
assert(bitcoin_tx_check(tx));
return tx;
}