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/* Commit tx without HTLC support; needed for openingd. */
#ifndef LIGHTNING_COMMON_INITIAL_COMMIT_TX_H
#define LIGHTNING_COMMON_INITIAL_COMMIT_TX_H
#include "config.h"
#include <bitcoin/pubkey.h>
#include <common/htlc.h>
struct keyset;
/* BOLT #3:
*
* This obscures the number of commitments made on the channel in the
* case of unilateral close, yet still provides a useful index for
* both nodes (who know the `payment_basepoint`s) to quickly find a
* revoked commitment transaction.
*/
u64 commit_number_obscurer(const struct pubkey *opener_payment_basepoint,
const struct pubkey *accepter_payment_basepoint);
/* Helper to calculate the base fee if we have this many htlc outputs */
static inline u64 commit_tx_base_fee(u32 feerate_per_kw,
size_t num_untrimmed_htlcs)
{
u64 weight;
/* BOLT #3:
*
* The base fee for a commitment transaction MUST BE
* calculated to match:
*
* 1. Start with `weight` = 724.
*/
weight = 724;
/* BOLT #3:
*
* 2. For each committed HTLC, if that output is not trimmed
* as specified in [Trimmed Outputs](#trimmed-outputs), add
* 172 to `weight`.
*/
weight += 172 * num_untrimmed_htlcs;
/* BOLT #3:
*
* 3. Multiply `feerate_per_kw` by `weight`, divide by 1000
* (rounding down).
*/
return feerate_per_kw * weight / 1000;
}
/**
* initial_commit_tx: create (unsigned) commitment tx to spend the funding tx output
* @ctx: context to allocate transaction and @htlc_map from.
* @funding_txid, @funding_out, @funding_satoshis: funding outpoint.
* @funder: is the LOCAL or REMOTE paying the fee?
* @keyset: keys derived for this commit tx.
* @feerate_per_kw: feerate to use
* @dust_limit_satoshis: dust limit below which to trim outputs.
* @self_pay_msat: amount to pay directly to self
* @other_pay_msat: amount to pay directly to the other side
* @obscured_commitment_number: number to encode in commitment transaction
* @side: side to generate commitment transaction for.
*
* We need to be able to generate the remote side's tx to create signatures,
* but the BOLT is expressed in terms of generating our local commitment
* transaction, so we carefully use the terms "self" and "other" here.
*/
struct bitcoin_tx *initial_commit_tx(const tal_t *ctx,
const struct bitcoin_txid *funding_txid,
unsigned int funding_txout,
u64 funding_satoshis,
enum side funder,
u16 to_self_delay,
const struct keyset *keyset,
u32 feerate_per_kw,
u64 dust_limit_satoshis,
u64 self_pay_msat,
u64 other_pay_msat,
u64 obscured_commitment_number,
enum side side);
/* try_subtract_fee - take away this fee from the funder, or all if insufficient. */
void try_subtract_fee(enum side funder, enum side side,
u64 base_fee_msat, u64 *self_msat, u64 *other_msat);
/* Generate the witness script for the to-self output:
* scriptpubkey_p2wsh(ctx, wscript) gives the scriptpubkey */
u8 *to_self_wscript(const tal_t *ctx,
u16 to_self_delay,
const struct keyset *keyset);
/* To-other is simply: scriptpubkey_p2wpkh(tx, keyset->other_payment_key) */
#endif /* LIGHTNING_COMMON_INITIAL_COMMIT_TX_H */