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gossipd: query unknown short_channel_ids, note if they were really missing.

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The first sign that we're missing gossip is that we get a channel_update
for an unknown channel.  The peer might be wrong (or lying), but if it turns
out to be a real channel, we were definitely missing something.

This patch does two things: queries when we get an unknown channel_update,
and then notes that a channel_announcement was from such an update when
it's finally processed.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2019-06-12 08:58:07 +09:30
parent 18069ab3da
commit b9053767e7
1 changed files with 55 additions and 6 deletions
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61
gossipd/gossipd.c
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@ -116,6 +116,9 @@ struct daemon {
/* Do we think we're missing gossip? */
bool gossip_missing;
/* Channels we've heard about, but don't know. */
struct short_channel_id *unknown_scids;
};
/* This represents each peer we're gossiping with */
@ -572,6 +575,27 @@ static bool query_short_channel_ids(struct daemon *daemon,
return true;
}
/*~ This peer told us about an update to an unknown channel. Ask it for
* a channel_announcement. */
static void query_unknown_channel(struct daemon *daemon,
struct peer *peer,
const struct short_channel_id *id)
{
/* Don't go overboard if we're already asking for a lot. */
if (tal_count(daemon->unknown_scids) > 1000)
return;
/* Check we're not already getting this one. */
for (size_t i = 0; i < tal_count(daemon->unknown_scids); i++)
if (short_channel_id_eq(&daemon->unknown_scids[i], id))
return;
tal_arr_expand(&daemon->unknown_scids, *id);
/* This is best effort: if peer is busy, we'll try next time. */
query_short_channel_ids(daemon, peer, daemon->unknown_scids, true);
}
/*~Routines to handle gossip messages from peer, forwarded by subdaemons.
*-----------------------------------------------------------------------
*
@ -593,7 +617,9 @@ static const u8 *handle_channel_announcement_msg(struct peer *peer,
const struct short_channel_id *scid;
const u8 *err;
/* If it's OK, tells us the short_channel_id to lookup */
/* If it's OK, tells us the short_channel_id to lookup; it notes
* if this is the unknown channel the peer was looking for (in
* which case, it frees and NULLs that ptr) */
err = handle_channel_announcement(peer->daemon->rstate, msg, &scid);
if (err)
return err;
@ -605,11 +631,18 @@ static const u8 *handle_channel_announcement_msg(struct peer *peer,
static u8 *handle_channel_update_msg(struct peer *peer, const u8 *msg)
{
struct short_channel_id unknown_scid;
/* Hand the channel_update to the routing code */
u8 *err = handle_channel_update(peer->daemon->rstate, msg, "subdaemon",
NULL);
if (err)
u8 *err;
unknown_scid.u64 = 0;
err = handle_channel_update(peer->daemon->rstate, msg, "subdaemon",
&unknown_scid);
if (err) {
if (unknown_scid.u64 != 0)
query_unknown_channel(peer->daemon, peer, &unknown_scid);
return err;
}
/*~ As a nasty compromise in the spec, we only forward channel_announce
* once we have a channel_update; the channel isn't *usable* for
@ -2571,12 +2604,27 @@ static struct io_plan *handle_txout_reply(struct io_conn *conn,
struct short_channel_id scid;
u8 *outscript;
struct amount_sat sat;
bool was_unknown;
if (!fromwire_gossip_get_txout_reply(msg, msg, &scid, &sat, &outscript))
master_badmsg(WIRE_GOSSIP_GET_TXOUT_REPLY, msg);
/* Were we looking specifically for this? */
was_unknown = false;
for (size_t i = 0; i < tal_count(daemon->unknown_scids); i++) {
if (short_channel_id_eq(&daemon->unknown_scids[i], &scid)) {
was_unknown = true;
tal_arr_remove(&daemon->unknown_scids, i);
break;
}
}
/* Outscript is NULL if it's not an unspent output */
handle_pending_cannouncement(daemon->rstate, &scid, sat, outscript);
if (handle_pending_cannouncement(daemon->rstate, &scid, sat, outscript)
&& was_unknown) {
/* It was real: we're missing gossip. */
gossip_missing(daemon);
}
/* Anywhere we might have announced a channel, we check if it's time to
* announce ourselves (ie. if we just announced our own first channel) */
@ -2840,7 +2888,8 @@ int main(int argc, char *argv[])
daemon = tal(NULL, struct daemon);
list_head_init(&daemon->peers);
daemon->gossip_missing = false;
daemon->unknown_scids = tal_arr(daemon, struct short_channel_id, 0);
daemon->gossip_missing = NULL;
/* Note the use of time_mono() here. That's a monotonic clock, which
* is really useful: it can only be used to measure relative events