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