core-lightning/common/initial_channel.h

/* This represents a channel with no HTLCs: all that's required for openingd. */
#ifndef LIGHTNING_COMMON_INITIAL_CHANNEL_H
#define LIGHTNING_COMMON_INITIAL_CHANNEL_H
#include "config.h"

#include <bitcoin/pubkey.h>
#include <bitcoin/shadouble.h>
#include <ccan/short_types/short_types.h>
#include <ccan/tal/tal.h>
#include <common/channel_config.h>
#include <common/derive_basepoints.h>
#include <common/htlc.h>
#include <stdbool.h>

struct signature;
struct added_htlc;
struct failed_htlc;
struct fulfilled_htlc;

/* View from each side */
struct channel_view {
	/* Current feerate in satoshis per 1000 weight. */
	u32 feerate_per_kw;

	/* How much is owed to each side (includes pending changes) */
	u64 owed_msat[NUM_SIDES];
};

struct channel {
	/* Funding txid and output. */
	struct bitcoin_txid funding_txid;
	unsigned int funding_txout;

	/* Keys used to spend funding tx. */
	struct pubkey funding_pubkey[NUM_SIDES];

	/* Millisatoshis in from commitment tx */
	u64 funding_msat;

	/* Who is paying fees. */
	enum side funder;

	/* Limits and settings on this channel. */
	const struct channel_config *config[NUM_SIDES];

	/* Basepoints for deriving keys. */
	struct basepoints basepoints[NUM_SIDES];

	/* Mask for obscuring the encoding of the commitment number. */
	u64 commitment_number_obscurer;

	/* All live HTLCs for this channel */
	struct htlc_map *htlcs;

	/* Do we have changes pending for ourselves/other? */
	bool changes_pending[NUM_SIDES];

	/* What it looks like to each side. */
	struct channel_view view[NUM_SIDES];
};

/* Some requirements are self-specified (eg. my dust limit), others
 * are force upon the other side (eg. minimum htlc you can add).
 *
 * These values are also universally in msatsoshi.  These avoid
 * confusion: use them! */

/* BOLT #2:
 *
 * `dust_limit_satoshis` is the threshold below which outputs should not be
 * generated for this node's commitment or HTLC transaction */
static inline u64 dust_limit_satoshis(const struct channel *channel,
				      enum side side)
{
	return channel->config[side]->dust_limit_satoshis;
}
/* BOLT #2:
 *
 * `max_htlc_value_in_flight_msat` is a cap on total value of
 * outstanding HTLCs, which allows a node to limit its exposure to
 * HTLCs */
static inline u64 max_htlc_value_in_flight_msat(const struct channel *channel,
						enum side recipient)
{
	return channel->config[recipient]->max_htlc_value_in_flight_msat;
}
/* BOLT #2:
 *
 * similarly, `max_accepted_htlcs` limits the number of outstanding
 * HTLCs the other node can offer. */
static inline u16 max_accepted_htlcs(const struct channel *channel,
				     enum side recipient)
{
	return channel->config[recipient]->max_accepted_htlcs;
}
/* BOLT #2:
 *
 * `channel_reserve_satoshis` is the minimum amount that the other
 * node is to keep as a direct payment. */
static inline u64 channel_reserve_msat(const struct channel *channel,
				       enum side side)
{
	return channel->config[!side]->channel_reserve_satoshis * 1000;
}
/* BOLT #2:
 *
 * `htlc_minimum_msat` indicates the smallest value HTLC this node will accept.
 */
static inline u32 htlc_minimum_msat(const struct channel *channel,
				    enum side recipient)
{
	return channel->config[recipient]->htlc_minimum_msat;
}
/* BOLT #2:
 *
 * `to_self_delay` is the number of blocks that the other node's
 * to-self outputs must be delayed, using `OP_CHECKSEQUENCEVERIFY`
 * delays */
static inline u16 to_self_delay(const struct channel *channel, enum side side)
{
	return channel->config[!side]->to_self_delay;
}


/**
 * new_initial_channel: Given initial fees and funding, what is initial state?
 * @ctx: tal context to allocate return value from.
 * @funding_txid: The commitment transaction id.
 * @funding_txout: The commitment transaction output number.
 * @funding_satoshis: The commitment transaction amount.
 * @local_msatoshi: The amount for the local side (remainder goes to remote)
 * @feerate_per_kw: feerate per kiloweight (satoshis) for the commitment
 *   transaction and HTLCS (at this stage, same for both sides)
 * @local: local channel configuration
 * @remote: remote channel configuration
 * @local_basepoints: local basepoints.
 * @remote_basepoints: remote basepoints.
 * @local_fundingkey: local funding key
 * @remote_fundingkey: remote funding key
 * @funder: which side initiated it.
 *
 * Returns channel, or NULL if malformed.
 */
struct channel *new_initial_channel(const tal_t *ctx,
				    const struct bitcoin_txid *funding_txid,
				    unsigned int funding_txout,
				    u64 funding_satoshis,
				    u64 local_msatoshi,
				    u32 feerate_per_kw,
				    const struct channel_config *local,
				    const struct channel_config *remote,
				    const struct basepoints *local_basepoints,
				    const struct basepoints *remote_basepoints,
				    const struct pubkey *local_funding_pubkey,
				    const struct pubkey *remote_funding_pubkey,
				    enum side funder);


/**
 * initial_channel_tx: Get the current commitment tx for the *empty* channel.
 * @ctx: tal context to allocate return value from.
 * @wscript: wscripts for the commitment tx.
 * @channel: The channel to evaluate
 * @per_commitment_point: Per-commitment point to determine keys
 * @side: which side to get the commitment transaction for
 *
 * Returns the unsigned initial commitment transaction for @side, or NULL
 * if the channel size was insufficient to cover fees or reserves.
 */
struct bitcoin_tx *initial_channel_tx(const tal_t *ctx,
				      const u8 **wscript,
				      const struct channel *channel,
				      const struct pubkey *per_commitment_point,
				      enum side side);

#endif /* LIGHTNING_COMMON_INITIAL_CHANNEL_H */