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offers: generalize "best peer" logic into core.

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We use this for invoices published by unannounced nodes: want
something very similar for offers, so generalize and expose it.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2024-07-17 18:32:11 +09:30
parent ca1b469c1a
commit 55982fe549
3 changed files with 119 additions and 85 deletions
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84
plugins/offers.c
View File

@ -271,6 +271,90 @@ static struct command_result *onion_message_recv(struct command *cmd,
return command_hook_success(cmd);
}
struct find_best_peer_data {
struct command_result *(*cb)(struct command *,
const struct chaninfo *,
void *);
int needed_feature;
void *arg;
};
static struct command_result *listincoming_done(struct command *cmd,
const char *buf,
const jsmntok_t *result,
struct find_best_peer_data *data)
{
const jsmntok_t *arr, *t;
size_t i;
struct chaninfo *best = NULL;
arr = json_get_member(buf, result, "incoming");
json_for_each_arr(i, t, arr) {
struct chaninfo ci;
const jsmntok_t *pftok;
u8 *features;
const char *err;
struct amount_msat feebase;
err = json_scan(tmpctx, buf, t,
"{id:%,"
"incoming_capacity_msat:%,"
"htlc_min_msat:%,"
"htlc_max_msat:%,"
"fee_base_msat:%,"
"fee_proportional_millionths:%,"
"cltv_expiry_delta:%}",
JSON_SCAN(json_to_pubkey, &ci.id),
JSON_SCAN(json_to_msat, &ci.capacity),
JSON_SCAN(json_to_msat, &ci.htlc_min),
JSON_SCAN(json_to_msat, &ci.htlc_max),
JSON_SCAN(json_to_msat, &feebase),
JSON_SCAN(json_to_u32, &ci.feeppm),
JSON_SCAN(json_to_u32, &ci.cltv));
if (err) {
plugin_log(cmd->plugin, LOG_BROKEN,
"Could not parse listincoming: %s",
err);
continue;
}
ci.feebase = feebase.millisatoshis; /* Raw: feebase */
/* Not presented if there's no channel_announcement for peer:
* we could use listpeers, but if it's private we probably
* don't want to blinded route through it! */
pftok = json_get_member(buf, t, "peer_features");
if (!pftok)
continue;
features = json_tok_bin_from_hex(tmpctx, buf, pftok);
if (!feature_offered(features, data->needed_feature))
continue;
if (!best || amount_msat_greater(ci.capacity, best->capacity))
best = tal_dup(tmpctx, struct chaninfo, &ci);
}
/* Free data if they don't */
tal_steal(tmpctx, data);
return data->cb(cmd, best, data->arg);
}
struct command_result *find_best_peer_(struct command *cmd,
int needed_feature,
struct command_result *(*cb)(struct command *,
const struct chaninfo *,
void *),
void *arg)
{
struct out_req *req;
struct find_best_peer_data *data = tal(cmd, struct find_best_peer_data);
data->cb = cb;
data->arg = arg;
data->needed_feature = needed_feature;
req = jsonrpc_request_start(cmd->plugin, cmd, "listincoming",
listincoming_done, forward_error, data);
return send_outreq(cmd->plugin, req);
}
static const struct plugin_hook hooks[] = {
{
"onion_message_recv",

24
plugins/offers.h
View File

@ -65,4 +65,28 @@ inject_onionmessage_(struct command *cmd,
/* Get the (latest) gossmap */
struct gossmap *get_gossmap(struct plugin *plugin);
/* Get the best (private) channel */
struct chaninfo {
struct pubkey id;
struct amount_msat capacity, htlc_min, htlc_max;
u32 feebase, feeppm, cltv;
};
/* Calls listpeerchannels, then cb with best peer (if any!) which has needed_feature */
struct command_result *find_best_peer_(struct command *cmd,
int needed_feature,
struct command_result *(*cb)(struct command *,
const struct chaninfo *,
void *),
void *arg);
#define find_best_peer(cmd, needed_feature, cb, arg) \
find_best_peer_((cmd), (needed_feature), \
typesafe_cb_preargs(struct command_result *, void *, \
(cb), (arg), \
struct command *, \
const struct chaninfo *), \
(arg))
#endif /* LIGHTNING_PLUGINS_OFFERS_H */

96
plugins/offers_invreq_hook.c
View File

@ -234,93 +234,16 @@ static struct command_result *create_invoicereq(struct command *cmd,
return send_outreq(cmd->plugin, req);
}
/* If we only have private channels, we need to add a blinded path to the
* invoice. We need to choose a peer who supports blinded payments, too. */
struct chaninfo {
struct pubkey id;
struct short_channel_id scid;
struct amount_msat capacity, htlc_min, htlc_max;
u32 feebase, feeppm, cltv;
bool public;
};
/* FIXME: This is naive:
* - Only creates if we have no public channels.
* - Always creates a path from direct neighbor.
* - Doesn't append dummy hops.
* - Doesn't pad to length.
*/
/* (We only create if we have to, because our code doesn't handle
* making a payment if the blinded path starts with ourselves!) */
static struct command_result *listincoming_done(struct command *cmd,
const char *buf,
const jsmntok_t *result,
struct invreq *ir)
static struct command_result *found_best_peer(struct command *cmd,
const struct chaninfo *best,
struct invreq *ir)
{
const jsmntok_t *arr, *t;
size_t i;
struct chaninfo *best = NULL;
bool any_public = false;
arr = json_get_member(buf, result, "incoming");
json_for_each_arr(i, t, arr) {
struct chaninfo ci;
const jsmntok_t *pftok;
u8 *features;
const char *err;
struct amount_msat feebase;
err = json_scan(tmpctx, buf, t,
"{id:%,"
"incoming_capacity_msat:%,"
"htlc_min_msat:%,"
"htlc_max_msat:%,"
"fee_base_msat:%,"
"fee_proportional_millionths:%,"
"cltv_expiry_delta:%,"
"short_channel_id:%,"
"public:%}",
JSON_SCAN(json_to_pubkey, &ci.id),
JSON_SCAN(json_to_msat, &ci.capacity),
JSON_SCAN(json_to_msat, &ci.htlc_min),
JSON_SCAN(json_to_msat, &ci.htlc_max),
JSON_SCAN(json_to_msat, &feebase),
JSON_SCAN(json_to_u32, &ci.feeppm),
JSON_SCAN(json_to_u32, &ci.cltv),
JSON_SCAN(json_to_short_channel_id, &ci.scid),
JSON_SCAN(json_to_bool, &ci.public));
if (err) {
plugin_log(cmd->plugin, LOG_BROKEN,
"Could not parse listincoming: %s",
err);
continue;
}
ci.feebase = feebase.millisatoshis; /* Raw: feebase */
any_public |= ci.public;
/* Not presented if there's no channel_announcement for peer:
* we could use listpeers, but if it's private we probably
* don't want to blinded route through it! */
pftok = json_get_member(buf, t, "peer_features");
if (!pftok)
continue;
features = json_tok_bin_from_hex(tmpctx, buf, pftok);
if (!feature_offered(features, OPT_ROUTE_BLINDING))
continue;
if (amount_msat_less(ci.htlc_max,
amount_msat(*ir->inv->invoice_amount)))
continue;
/* Only pick a private one if no public candidates. */
if (!best || (!best->public && ci.public))
best = tal_dup(tmpctx, struct chaninfo, &ci);
}
/* If there are any public channels, don't add. */
if (any_public)
goto done;
/* BOLT-offers #12:
* - MUST include `invoice_paths` containing one or more paths to the node.
* - MUST specify `invoice_paths` in order of most-preferred to
@ -392,18 +315,21 @@ static struct command_result *listincoming_done(struct command *cmd,
ir->inv->invoice_blindedpay[0]->features = NULL;
}
done:
return create_invoicereq(cmd, ir);
}
static struct command_result *add_blindedpaths(struct command *cmd,
struct invreq *ir)
{
struct out_req *req;
struct node_id local_nodeid;
req = jsonrpc_request_start(cmd->plugin, cmd, "listincoming",
listincoming_done, listincoming_done, ir);
return send_outreq(cmd->plugin, req);
/* Don't bother if we're public */
node_id_from_pubkey(&local_nodeid, &id);
if (gossmap_find_node(get_gossmap(cmd->plugin), &local_nodeid))
create_invoicereq(cmd, ir);
return find_best_peer(cmd, OPT_ROUTE_BLINDING,
found_best_peer, ir);
}
static struct command_result *check_period(struct command *cmd,