core-lightning/plugins/renepay/uncertainty_network.c

#include "config.h"
#include <common/bolt11.h>
#include <common/gossmods_listpeerchannels.h>
#include <plugins/renepay/pay.h>
#include <plugins/renepay/uncertainty_network.h>

static bool chan_extra_check_invariants(struct chan_extra *ce)
{
	bool all_ok = true;
	for(int i=0;i<2;++i)
	{
		all_ok &= amount_msat_less_eq(ce->half[i].known_min,
					      ce->half[i].known_max);
		all_ok &= amount_msat_less_eq(ce->half[i].known_max,
					      ce->capacity);
	}
	struct amount_msat diff_cb,diff_ca;

	all_ok &= amount_msat_sub(&diff_cb,ce->capacity,ce->half[1].known_max);
	all_ok &= amount_msat_sub(&diff_ca,ce->capacity,ce->half[1].known_min);

	all_ok &= amount_msat_eq(ce->half[0].known_min,diff_cb);
	all_ok &= amount_msat_eq(ce->half[0].known_max,diff_ca);
	return all_ok;
}


/* Checks the entire uncertainty network for invariant violations. */
bool uncertainty_network_check_invariants(struct chan_extra_map *chan_extra_map)
{
	bool all_ok = true;

	struct chan_extra_map_iter it;
	for(struct chan_extra *ce = chan_extra_map_first(chan_extra_map,&it);
	    ce && all_ok;
	    ce=chan_extra_map_next(chan_extra_map,&it))
	{
		all_ok &= chan_extra_check_invariants(ce);
	}

	return all_ok;
}

static void add_hintchan(
		struct chan_extra_map *chan_extra_map,
		struct gossmap_localmods *local_gossmods,
		const struct node_id *src,
		const struct node_id *dst,
		u16 cltv_expiry_delta,
		const struct short_channel_id scid,
		u32 fee_base_msat,
		u32 fee_proportional_millionths)
{
	int dir = node_id_cmp(src, dst) < 0 ? 0 : 1;

	struct chan_extra *ce = chan_extra_map_get(chan_extra_map,
						   scid);
	if(!ce)
	{
		/* this channel is not public, we don't know his capacity */
		// TODO(eduardo): one possible solution is set the capacity to
		// MAX_CAP and the state to [0,MAX_CAP]. Alternatively we set
		// the capacity to amoung and state to [amount,amount].
		ce = new_chan_extra(chan_extra_map,
				    scid,
				    MAX_CAP);
		/* FIXME: features? */
		gossmap_local_addchan(local_gossmods,
				      src, dst, &scid, NULL);
		gossmap_local_updatechan(local_gossmods,
					 &scid,
					 /* We assume any HTLC is allowed */
					 AMOUNT_MSAT(0), MAX_CAP,
					 fee_base_msat, fee_proportional_millionths,
					 cltv_expiry_delta,
					 true,
					 dir);
	}

	/* It is wrong to assume that this channel has sufficient capacity!
	 * Doing so leads to knowledge updates in which the known min liquidity
	 * is greater than the channel's capacity. */
	// chan_extra_can_send(chan_extra_map,scid,dir,amount);
}

/* Add routehints provided by bolt11 */
void uncertainty_network_add_routehints(
		struct chan_extra_map *chan_extra_map,
		const struct route_info **routes,
		struct payment *p)
{
	for (size_t i = 0; i < tal_count(routes); i++) {
		/* Each one, presumably, leads to the destination */
		const struct route_info *r = routes[i];
		const struct node_id *end = & p->destination;
		for (int j = tal_count(r)-1; j >= 0; j--) {
			add_hintchan(
				chan_extra_map,
				p->local_gossmods,
				&r[j].pubkey, end,
				r[j].cltv_expiry_delta,
				r[j].short_channel_id,
				r[j].fee_base_msat,
				r[j].fee_proportional_millionths);
			end = &r[j].pubkey;
		}
	}
}

/* Mirror the gossmap in the public uncertainty network.
 * result: Every channel in gossmap must have associated data in chan_extra_map,
 * while every channel in chan_extra_map is also registered in gossmap.
 * */
void uncertainty_network_update(
		const struct gossmap *gossmap,
		struct chan_extra_map *chan_extra_map)
{
	const tal_t* this_ctx = tal(tmpctx,tal_t);

	// For each chan in chan_extra_map remove if not in the gossmap
	struct short_channel_id *del_list
		= tal_arr(this_ctx,struct short_channel_id,0);

	struct chan_extra_map_iter it;
	for(struct chan_extra *ce = chan_extra_map_first(chan_extra_map,&it);
	    ce;
	    ce=chan_extra_map_next(chan_extra_map,&it))
	{
		struct gossmap_chan * chan = gossmap_find_chan(gossmap,&ce->scid);
		/* Only if the channel is not in the gossmap and there are not
		 * HTLCs pending we can remove it. */
		if(!chan && !chan_extra_is_busy(ce))
		{
			// TODO(eduardo): is this efficiently implemented?
			// otherwise i'll use a ccan list
			tal_arr_expand(&del_list, ce->scid);
		}
	}

	for(size_t i=0;i<tal_count(del_list);++i)
	{
 		struct chan_extra *ce = chan_extra_map_get(chan_extra_map,del_list[i]);
		if(!ce)
		{
			plugin_err(pay_plugin->plugin,"%s (line %d) unexpected chan_extra ce is NULL",
				__PRETTY_FUNCTION__,
				__LINE__);
		}
		chan_extra_map_del(chan_extra_map, ce);
		tal_free(ce);
		// TODO(eduardo): if you had added a destructor to ce, you could have removed
		// the ce from the map automatically.

	}

	// For each channel in the gossmap, create a extra data in
	// chan_extra_map
	for(struct gossmap_chan *chan = gossmap_first_chan(gossmap);
	    chan;
	    chan=gossmap_next_chan(gossmap,chan))
	{
		struct short_channel_id scid =
			gossmap_chan_scid(gossmap,chan);
		struct chan_extra *ce = chan_extra_map_get(chan_extra_map,
							   gossmap_chan_scid(gossmap,chan));
		if(!ce)
		{
			struct amount_sat cap;
			struct amount_msat cap_msat;

			if(!gossmap_chan_get_capacity(gossmap,chan,&cap))
			{
				plugin_err(pay_plugin->plugin,"%s (line %d) unable to fetch channel capacity",
					__PRETTY_FUNCTION__,
					__LINE__);
			}
			if(!amount_sat_to_msat(&cap_msat,cap))
			{
				plugin_err(pay_plugin->plugin,"%s (line %d) unable convert sat to msat",
					__PRETTY_FUNCTION__,
					__LINE__);
			}
			new_chan_extra(chan_extra_map,scid,cap_msat);
		}
	}
	tal_free(this_ctx);
}

void uncertainty_network_flow_success(
		struct chan_extra_map *chan_extra_map,
		struct pay_flow *pf)
{
	char *errmsg;
	for (size_t i = 0; i < tal_count(pf->path_scidds); i++)
	{
		const char *old_state
		    = fmt_chan_extra_details(tmpctx, pay_plugin->chan_extra_map,
					   &pf->path_scidds[i]);
		if (!chan_extra_sent_success(tmpctx, chan_extra_map,
					     &pf->path_scidds[i],
					     pf->amounts[i], &errmsg)) {
			plugin_err(pay_plugin->plugin,
				   "chan_extra_sent_success failed: %s",
				   errmsg);
		}
		payflow_note(pf, LOG_INFORM,
			     "Success forwarding amount %s in channel %s, "
			     "state change %s -> %s",
			     fmt_amount_msat(tmpctx, pf->amounts[i]),
			     type_to_string(tmpctx, struct short_channel_id_dir,
					    &pf->path_scidds[i]),
			     old_state,
			     fmt_chan_extra_details(tmpctx,
						    pay_plugin->chan_extra_map,
						    &pf->path_scidds[i]));
	}
}
/* All parts up to erridx succeeded, so we know something about min
 * capacity! */
void uncertainty_network_channel_can_send(
		struct chan_extra_map * chan_extra_map,
		struct pay_flow *pf,
		u32 erridx)
{
	char *fail;
	for (size_t i = 0; i < erridx; i++)
	{
		if (!chan_extra_can_send(
			tmpctx, chan_extra_map, &pf->path_scidds[i],
			&fail)) {
			plugin_err(pay_plugin->plugin,
				   "chan_extra_can_send failed: %s", fail);
		}
	}
}

void uncertainty_network_update_from_listpeerchannels(struct payment *p,
						      const struct short_channel_id_dir *scidd,
						      struct amount_msat max,
						      bool enabled,
						      const char *buf,
						      const jsmntok_t *chantok,
						      struct chan_extra_map *chan_extra_map)
{
	struct chan_extra *ce;
	char *errmsg;

	if (!enabled) {
		payment_disable_chan(p, scidd->scid, LOG_DBG,
				     "listpeerchannelks says not enabled");
		return;
	}

	ce = chan_extra_map_get(chan_extra_map, scidd->scid);
	if (!ce) {
		const jsmntok_t *totaltok;
		struct amount_msat capacity;

		/* this channel is not public, but it belongs to us */
		totaltok = json_get_member(buf, chantok, "total_msat");
		if (!totaltok) {
			errmsg = tal_fmt(
			    tmpctx,
			    "Failed to update channel from listpeerchannels "
			    "scid=%s, missing total_msat",
			    type_to_string(tmpctx, struct short_channel_id,
					   &scidd->scid));
			goto error;
		}
		if (!json_to_msat(buf, totaltok, &capacity)) {
			errmsg = tal_fmt(
			    tmpctx,
			    "Failed to update channel from listpeerchannels "
			    "scid=%s, cannot parse total_msat",
			    type_to_string(tmpctx, struct short_channel_id,
					   &scidd->scid));
			goto error;
		}

		ce = new_chan_extra(chan_extra_map, scidd->scid, capacity);
	}

	/* FIXME: There is a bug with us trying to send more down a local
	 * channel (after fees) than it has capacity.  For now, we reduce
	 * our capacity by 1% of total, to give fee headroom. */
	if (!amount_msat_sub(&max, max, amount_msat_div(p->amount, 100)))
		max = AMOUNT_MSAT(0);

	// TODO(eduardo): this does not include pending HTLC of previous
	// payments!
	/* We know min and max liquidity exactly now! */
	if (!chan_extra_set_liquidity(tmpctx, chan_extra_map, scidd, max,
				      &errmsg)) {
		plugin_err(pay_plugin->plugin,
			   "chan_extra_set_liquidity failed: %s", errmsg);
	}
	return;

	error:
	plugin_log(pay_plugin->plugin, LOG_UNUSUAL, "%s", errmsg);
}

/* Forget ALL channels information by a fraction of the capacity. */
void uncertainty_network_relax_fraction(struct chan_extra_map *chan_extra_map,
					double fraction)
{
	struct chan_extra_map_iter it;
	char *fail;
	for (struct chan_extra *ce = chan_extra_map_first(chan_extra_map, &it);
	     ce; ce = chan_extra_map_next(chan_extra_map, &it)) {
		if (!chan_extra_relax_fraction(tmpctx, ce, fraction, &fail)) {
			plugin_err(pay_plugin->plugin,
				   "chan_extra_relax_fraction failed for "
				   "channel %s: %s",
				   type_to_string(tmpctx,
						  struct short_channel_id,
						  &ce->scid),
				   fail);
		}
	}
}