lightning/common/gossmap.h

#ifndef LIGHTNING_COMMON_GOSSMAP_H
#define LIGHTNING_COMMON_GOSSMAP_H
#include "config.h"
#include <bitcoin/short_channel_id.h>
#include <ccan/typesafe_cb/typesafe_cb.h>
#include <common/amount.h>

struct node_id;
struct pubkey32;

/* 5 bit exponent, 11 bit mantissa approximations of min/max */
typedef u16 fp16_t;

struct gossmap_node {
	/* Offset in memory map for node_announce, or 0. */
	u32 nann_off;
	u32 num_chans;
	u32 *chan_idxs;
};

struct gossmap_chan {
	u32 cann_off;
	/* Technically redundant, but we have a hole anyway. */
	u32 scid_off;
	/* two nodes we connect (lesser idx first) */
	struct half_chan {
		/* Top bit indicates it's enabled */
		u32 enabled: 1;
		u32 nodeidx : 31;
		fp16_t htlc_min, htlc_max;

		/* millisatoshi. */
		u64 base_fee : 24;
		/* millionths */
		u64 proportional_fee : 20;
		/* Delay for HTLC in blocks. */
		u64 delay : 20;
	} half[2];
};

static inline u64 fp16_to_u64(fp16_t val)
{
	return ((u64)val & ((1 << 11)-1)) << (val >> 11);
}

struct gossmap *gossmap_load(const tal_t *ctx, const char *filename);

/* Call this before using to ensure it's up-to-date.  Returns true if something
 * was updated. Note: this can scramble node and chan indexes! */
bool gossmap_refresh(struct gossmap *map);

/* Each channel has a unique (low) index. */
u32 gossmap_node_idx(const struct gossmap *map, const struct gossmap_node *node);
u32 gossmap_chan_idx(const struct gossmap *map, const struct gossmap_chan *chan);

/* Every node_idx/chan_idx will be < these.
 * These values can change across calls to gossmap_check. */
u32 gossmap_max_node_idx(const struct gossmap *map);
u32 gossmap_max_chan_idx(const struct gossmap *map);

/* Find node with this node_id */
struct gossmap_node *gossmap_find_node(const struct gossmap *map,
				       const struct node_id *id);
/* Find chan with this short_channel_id */
struct gossmap_chan *gossmap_find_chan(const struct gossmap *map,
				       const struct short_channel_id *scid);

/* Get the short_channel_id of this chan */
struct short_channel_id gossmap_chan_scid(const struct gossmap *map,
					  const struct gossmap_chan *c);

/* Given a struct node, get the node_id */
void gossmap_node_get_id(const struct gossmap *map,
			 const struct gossmap_node *node,
			 struct node_id *id);

/* Do we have any values for this halfchannel ? */
static inline bool gossmap_chan_set(const struct gossmap_chan *chan, int dir)
{
	return chan->half[dir].htlc_max != 0;
}

/* Get the announcement msg which created this chan */
u8 *gossmap_chan_get_announce(const tal_t *ctx,
			      const struct gossmap *map,
			      const struct gossmap_chan *c);

/* Get the announcement msg (if any) for this node. */
u8 *gossmap_node_get_announce(const tal_t *ctx,
			      const struct gossmap *map,
			      const struct gossmap_node *n);

/* Return the feature bit (odd or even), or -1 if neither. */
int gossmap_chan_get_feature(const struct gossmap *map,
			     const struct gossmap_chan *c,
			     int fbit);

/* Return the feature bit (odd or even), or -1 if neither (or no announcement) */
int gossmap_node_get_feature(const struct gossmap *map,
			     const struct gossmap_node *n,
			     int fbit);

/* Given a struct node, get the nth channel, and tell us if we're half[0/1].
 * n must be less than node->num_chans */
struct gossmap_chan *gossmap_nth_chan(const struct gossmap *map,
				      const struct gossmap_node *node,
				      u32 n,
				      int *which_half);

/* Given a struct chan, get the nth node, where n is 0 or 1. */
struct gossmap_node *gossmap_nth_node(const struct gossmap *map,
				      const struct gossmap_chan *chan,
				      int n);

/* Can this channel send this amount? */
bool gossmap_chan_capacity(const struct gossmap_chan *chan,
			   int direction,
			   struct amount_msat amount);

/* Remove a channel from the map (warning! realloc can move gossmap_chan
 * and gossmap_node ptrs!) */
void gossmap_remove_chan(struct gossmap *map, struct gossmap_chan *chan);

/* Remove node (by removing all its channels) */
void gossmap_remove_node(struct gossmap *map, struct gossmap_node *node);

/* Unsorted iterate through (do not add/remove channels or nodes!) */
size_t gossmap_num_nodes(const struct gossmap *map);

struct gossmap_node *gossmap_first_node(const struct gossmap *map);
struct gossmap_node *gossmap_next_node(const struct gossmap *map,
				       const struct gossmap_node *prev);

/* Unsorted iterate through (do not add/remove channels or nodes!) */
size_t gossmap_num_chans(const struct gossmap *map);

struct gossmap_chan *gossmap_first_chan(const struct gossmap *map);
struct gossmap_chan *gossmap_next_chan(const struct gossmap *map,
				       struct gossmap_chan *prev);

/* Each x-only pubkey has two possible values: we can figure out which by
 * examining the gossmap. */
void gossmap_guess_node_id(const struct gossmap *map,
			   const struct pubkey32 *pubkey32,
			   struct node_id *id);

#endif /* LIGHTNING_COMMON_GOSSMAP_H */