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#include <bitcoin/script.h>
#include <bitcoin/tx.h>
#include <ccan/endian/endian.h>
#include <channeld/commit_tx.h>
#include <common/htlc_trim.h>
#include <common/htlc_tx.h>
#include <common/keyset.h>
#include <common/permute_tx.h>
#include <common/utils.h>
#ifndef SUPERVERBOSE
#define SUPERVERBOSE(...)
#endif
static bool trim(const struct htlc *htlc,
u32 feerate_per_kw,
struct amount_sat dust_limit,
enum side side)
{
return htlc_is_trimmed(htlc_owner(htlc), htlc->amount,
feerate_per_kw, dust_limit, side);
}
size_t commit_tx_num_untrimmed(const struct htlc **htlcs,
u32 feerate_per_kw,
struct amount_sat dust_limit,
enum side side)
{
size_t i, n;
for (i = n = 0; i < tal_count(htlcs); i++)
n += !trim(htlcs[i], feerate_per_kw, dust_limit, side);
return n;
}
static void add_offered_htlc_out(struct bitcoin_tx *tx, size_t n,
const struct htlc *htlc,
const struct keyset *keyset)
{
struct ripemd160 ripemd;
u8 *wscript, *p2wsh;
struct amount_sat amount = amount_msat_to_sat_round_down(htlc->amount);
ripemd160(&ripemd, htlc->rhash.u.u8, sizeof(htlc->rhash.u.u8));
wscript = htlc_offered_wscript(tx, &ripemd, keyset);
p2wsh = scriptpubkey_p2wsh(tx, wscript);
bitcoin_tx_add_output(tx, p2wsh, amount);
SUPERVERBOSE("# HTLC %" PRIu64 " offered %s wscript %s\n", htlc->id,
type_to_string(tmpctx, struct amount_sat, &amount),
tal_hex(wscript, wscript));
tal_free(wscript);
}
static void add_received_htlc_out(struct bitcoin_tx *tx, size_t n,
const struct htlc *htlc,
const struct keyset *keyset)
{
struct ripemd160 ripemd;
u8 *wscript, *p2wsh;
struct amount_sat amount;
ripemd160(&ripemd, htlc->rhash.u.u8, sizeof(htlc->rhash.u.u8));
wscript = htlc_received_wscript(tx, &ripemd, &htlc->expiry, keyset);
p2wsh = scriptpubkey_p2wsh(tx, wscript);
amount = amount_msat_to_sat_round_down(htlc->amount);
bitcoin_tx_add_output(tx, p2wsh, amount);
SUPERVERBOSE("# HTLC %"PRIu64" received %s wscript %s\n",
htlc->id,
type_to_string(tmpctx, struct amount_sat,
&amount),
tal_hex(wscript, wscript));
tal_free(wscript);
}
struct bitcoin_tx *commit_tx(const tal_t *ctx,
const struct chainparams *chainparams,
const struct bitcoin_txid *funding_txid,
unsigned int funding_txout,
struct amount_sat funding,
enum side funder,
u16 to_self_delay,
const struct keyset *keyset,
u32 feerate_per_kw,
struct amount_sat dust_limit,
struct amount_msat self_pay,
struct amount_msat other_pay,
const struct htlc **htlcs,
const struct htlc ***htlcmap,
u64 obscured_commitment_number,
enum side side)
{
struct amount_sat base_fee;
struct amount_msat total_pay;
struct bitcoin_tx *tx;
size_t i, n, untrimmed;
u32 *cltvs;
if (!amount_msat_add(&total_pay, self_pay, other_pay))
abort();
assert(!amount_msat_greater_sat(total_pay, funding));
/* BOLT #3:
*
* 1. Calculate which committed HTLCs need to be trimmed (see
* [Trimmed Outputs](#trimmed-outputs)).
*/
untrimmed = commit_tx_num_untrimmed(htlcs,
feerate_per_kw,
dust_limit, side);
/* BOLT #3:
*
* 2. Calculate the base [commitment transaction
* fee](#fee-calculation).
*/
base_fee = commit_tx_base_fee(feerate_per_kw, untrimmed);
SUPERVERBOSE("# base commitment transaction fee = %s\n",
type_to_string(tmpctx, struct amount_sat, &base_fee));
/* BOLT #3:
*
* 3. Subtract this base fee from the funder (either `to_local` or
* `to_remote`), with a floor of 0 (see [Fee Payment](#fee-payment)).
*/
try_subtract_fee(funder, side, base_fee, &self_pay, &other_pay);
#ifdef PRINT_ACTUAL_FEE
{
struct amount_sat out = AMOUNT_SAT(0);
bool ok = true;
for (i = 0; i < tal_count(htlcs); i++) {
if (!trim(htlcs[i], feerate_per_kw, dust_limit, side))
ok &= amount_sat_add(&out, out, amount_msat_to_sat_round_down(htlcs[i]->amount));
}
if (amount_msat_greater_sat(self_pay, dust_limit))
ok &= amount_sat_add(&out, out, amount_msat_to_sat_round_down(self_pay));
if (amount_msat_greater_sat(other_pay, dust_limit))
ok &= amount_sat_add(&out, out, amount_msat_to_sat_round_down(other_pay));
assert(ok);
SUPERVERBOSE("# actual commitment transaction fee = %"PRIu64"\n",
funding.satoshis - out.satoshis); /* Raw: test output */
}
#endif
/* Worst-case sizing: both to-local and to-remote outputs. */
tx = bitcoin_tx(ctx, chainparams, 1, untrimmed + 2);
/* We keep track of which outputs have which HTLCs */
*htlcmap = tal_arr(tx, const struct htlc *, tx->wtx->outputs_allocation_len);
/* We keep cltvs for tie-breaking HTLC outputs; we use the same order
* for sending the htlc txs, so it may matter. */
cltvs = tal_arr(tmpctx, u32, tx->wtx->outputs_allocation_len);
/* This could be done in a single loop, but we follow the BOLT
* literally to make comments in test vectors clearer. */
n = 0;
/* BOLT #3:
*
* 3. For every offered HTLC, if it is not trimmed, add an
* [offered HTLC output](#offered-htlc-outputs).
*/
for (i = 0; i < tal_count(htlcs); i++) {
if (htlc_owner(htlcs[i]) != side)
continue;
if (trim(htlcs[i], feerate_per_kw, dust_limit, side))
continue;
add_offered_htlc_out(tx, n, htlcs[i], keyset);
(*htlcmap)[n] = htlcs[i];
cltvs[n] = abs_locktime_to_blocks(&htlcs[i]->expiry);
n++;
}
/* BOLT #3:
*
* 4. For every received HTLC, if it is not trimmed, add an
* [received HTLC output](#received-htlc-outputs).
*/
for (i = 0; i < tal_count(htlcs); i++) {
if (htlc_owner(htlcs[i]) == side)
continue;
if (trim(htlcs[i], feerate_per_kw, dust_limit, side))
continue;
add_received_htlc_out(tx, n, htlcs[i], keyset);
(*htlcmap)[n] = htlcs[i];
cltvs[n] = abs_locktime_to_blocks(&htlcs[i]->expiry);
n++;
}
/* BOLT #3:
*
* 5. If the `to_local` amount is greater or equal to
* `dust_limit_satoshis`, add a [`to_local`
* output](#to_local-output).
*/
if (amount_msat_greater_eq_sat(self_pay, dust_limit)) {
u8 *wscript = to_self_wscript(tmpctx, to_self_delay,keyset);
u8 *p2wsh = scriptpubkey_p2wsh(tx, wscript);
struct amount_sat amount = amount_msat_to_sat_round_down(self_pay);
bitcoin_tx_add_output(tx, p2wsh, amount);
(*htlcmap)[n] = NULL;
/* We don't assign cltvs[n]: if we use it, order doesn't matter.
* However, valgrind will warn us something wierd is happening */
SUPERVERBOSE("# to-local amount %s wscript %s\n",
type_to_string(tmpctx, struct amount_sat, &amount),
tal_hex(tmpctx, wscript));
n++;
}
/* BOLT #3:
*
* 6. If the `to_remote` amount is greater or equal to
* `dust_limit_satoshis`, add a [`to_remote`
* output](#to_remote-output).
*/
if (amount_msat_greater_eq_sat(other_pay, dust_limit)) {
struct amount_sat amount = amount_msat_to_sat_round_down(other_pay);
u8 *p2wpkh =
scriptpubkey_p2wpkh(tx, &keyset->other_payment_key);
/* BOLT #3:
*
* #### `to_remote` Output
*
* This output sends funds to the other peer and thus is a simple
* P2WPKH to `remotepubkey`.
*/
int pos = bitcoin_tx_add_output(tx, p2wpkh, amount);
assert(pos == n);
(*htlcmap)[n] = NULL;
/* We don't assign cltvs[n]: if we use it, order doesn't matter.
* However, valgrind will warn us something wierd is happening */
SUPERVERBOSE("# to-remote amount %s P2WPKH(%s)\n",
type_to_string(tmpctx, struct amount_sat,
&amount),
type_to_string(tmpctx, struct pubkey,
&keyset->other_payment_key));
n++;
}
/* BOLT #2:
*
* - MUST set `channel_reserve_satoshis` greater than or equal to
* `dust_limit_satoshis`.
*/
/* This means there must be at least one output. */
assert(n > 0);
assert(n <= tx->wtx->outputs_allocation_len);
tal_resize(htlcmap, n);
/* BOLT #3:
*
* 7. Sort the outputs into [BIP 69+CLTV
* order](#transaction-input-and-output-ordering)
*/
permute_outputs(tx, cltvs, (const void **)*htlcmap);
/* BOLT #3:
*
* ## Commitment Transaction
*
* * version: 2
*/
assert(tx->wtx->version == 2);
/* BOLT #3:
*
* * locktime: upper 8 bits are 0x20, lower 24 bits are the lower 24 bits of the obscured commitment number
*/
tx->wtx->locktime
= (0x20000000 | (obscured_commitment_number & 0xFFFFFF));
/* BOLT #3:
*
* * txin count: 1
* * `txin[0]` outpoint: `txid` and `output_index` from
* `funding_created` message
*/
/* BOLT #3:
*
* * `txin[0]` sequence: upper 8 bits are 0x80, lower 24 bits are upper 24 bits of the obscured commitment number
*/
u32 sequence = (0x80000000 | ((obscured_commitment_number>>24) & 0xFFFFFF));
bitcoin_tx_add_input(tx, funding_txid, funding_txout, sequence, funding, NULL);
elements_tx_add_fee_output(tx);
return tx;
}