core-lightning/daemon/htlc.h

#ifndef LIGHTNING_DAEMON_HTLC_H
#define LIGHTNING_DAEMON_HTLC_H
#include "config.h"
#include "bitcoin/locktime.h"
#include "channel.h"
#include "htlc_state.h"
#include "pseudorand.h"
#include <assert.h>
#include <ccan/crypto/sha256/sha256.h>
#include <ccan/crypto/siphash24/siphash24.h>
#include <ccan/htable/htable_type.h>
#include <ccan/short_types/short_types.h>

/* What are we doing: adding or removing? */
#define HTLC_ADDING			0x400
#define HTLC_REMOVING			0x800

/* Uncommitted change is pending */
#define HTLC_F_PENDING			0x01
/* HTLC is in commit_tx */
#define HTLC_F_COMMITTED		0x02
/* We have revoked the previous commit_tx */
#define HTLC_F_REVOKED			0x04
/* We offered it it. */
#define HTLC_F_OWNER			0x08
/* HTLC was ever in a commit_tx */
#define HTLC_F_WAS_COMMITTED		0x10

/* Each of the above flags applies to both sides */
enum htlc_side {
	LOCAL,
	REMOTE
};

#define HTLC_FLAG(side,flag)		((flag) << ((side) * 5))

#define HTLC_REMOTE_F_PENDING		HTLC_FLAG(REMOTE,HTLC_F_PENDING)
#define HTLC_REMOTE_F_COMMITTED		HTLC_FLAG(REMOTE,HTLC_F_COMMITTED)
#define HTLC_REMOTE_F_REVOKED		HTLC_FLAG(REMOTE,HTLC_F_REVOKED)
#define HTLC_REMOTE_F_OWNER		HTLC_FLAG(REMOTE,HTLC_F_OWNER)
#define HTLC_REMOTE_F_WAS_COMMITTED	HTLC_FLAG(REMOTE,HTLC_F_WAS_COMMITTED)

#define HTLC_LOCAL_F_PENDING		HTLC_FLAG(LOCAL,HTLC_F_PENDING)
#define HTLC_LOCAL_F_COMMITTED		HTLC_FLAG(LOCAL,HTLC_F_COMMITTED)
#define HTLC_LOCAL_F_REVOKED		HTLC_FLAG(LOCAL,HTLC_F_REVOKED)
#define HTLC_LOCAL_F_OWNER		HTLC_FLAG(LOCAL,HTLC_F_OWNER)
#define HTLC_LOCAL_F_WAS_COMMITTED	HTLC_FLAG(LOCAL,HTLC_F_WAS_COMMITTED)

struct htlc {
	/* Useful for debugging, and decoding via ->src. */
	struct peer *peer;
	/* Block number where we abort if it's still live (OURS only) */
	u32 deadline;
	/* What's the status. */
	enum htlc_state state; 
	/* The unique ID for this peer and this direction (ours or theirs) */
	u64 id;
	/* The amount in millisatoshi. */
	u64 msatoshis;
	/* When the HTLC can no longer be redeemed. */
	struct abs_locktime expiry;
	/* The hash of the preimage which can redeem this HTLC */
	struct sha256 rhash;
	/* The preimage which hashes to rhash (if known) */
	struct rval *r;

	/* FIXME: We could union these together: */
	/* Routing information sent with this HTLC. */
	const u8 *routing;
	/* Previous HTLC (if any) which made us offer this (OURS only) */
	struct htlc *src;
};

const char *htlc_state_name(enum htlc_state s);
enum htlc_state htlc_state_from_name(const char *name);
bool htlc_changestate(struct htlc *h,
		      enum htlc_state oldstate,
		      enum htlc_state newstate,
		      bool db_commit);
int htlc_state_flags(enum htlc_state state);

static inline bool htlc_has(const struct htlc *h, int flag)
{
	return htlc_state_flags(h->state) & flag;
}

static inline enum htlc_side htlc_state_owner(enum htlc_state state)
{
	if (state < RCVD_ADD_HTLC) {
		assert((htlc_state_flags(state)
			& (HTLC_REMOTE_F_OWNER|HTLC_LOCAL_F_OWNER))
		       == HTLC_LOCAL_F_OWNER);
		return LOCAL;
	} else {
		assert((htlc_state_flags(state)
			& (HTLC_REMOTE_F_OWNER|HTLC_LOCAL_F_OWNER))
		       == HTLC_REMOTE_F_OWNER);
		return REMOTE;
	}
}

static inline enum htlc_side htlc_owner(const struct htlc *h)
{
	return htlc_state_owner(h->state);
}

/* FIXME: Transitional function. */
static inline enum channel_side htlc_channel_side(const struct htlc *h)
{
	if (htlc_owner(h) == LOCAL)
		return OURS;
	return THEIRS;
}

void htlc_undostate(struct htlc *h,
		    enum htlc_state oldstate, enum htlc_state newstate);

/* htlc_map: ID -> htlc mapping. */
static inline u64 htlc_key(const struct htlc *h)
{
	return h->id;
}
static inline bool htlc_cmp(const struct htlc *h, u64 id)
{
	return h->id == id;
}
static inline size_t htlc_hash(u64 id)
{
	return siphash24(siphash_seed(), &id, sizeof(id));
}
HTABLE_DEFINE_TYPE(struct htlc, htlc_key, htlc_hash, htlc_cmp, htlc_map);

static inline struct htlc *htlc_get(struct htlc_map *htlcs, u64 id, enum htlc_side owner)
{
	struct htlc *h;
	struct htlc_map_iter it;

	for (h = htlc_map_getfirst(htlcs, id, &it);
	     h;
	     h = htlc_map_getnext(htlcs, id, &it)) {
		if (h->id == id && htlc_has(h, HTLC_FLAG(owner,HTLC_F_OWNER)))
			return h;
	}
	return NULL;
}

static inline size_t htlc_map_count(const struct htlc_map *htlcs)
{
	return htlcs->raw.elems;
}

/* FIXME: Move these out of the hash! */
static inline bool htlc_is_dead(const struct htlc *htlc)
{
	return htlc->state == RCVD_REMOVE_ACK_REVOCATION
		|| htlc->state == SENT_REMOVE_ACK_REVOCATION;
}
#endif /* LIGHTNING_DAEMON_HTLC_H */