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connectd: fix accidental handling of old reconnections.

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We had multiple reports of channels being unilaterally closed because
it seemed like the peer was sending old revocation numbers.

Turns out, it was actually old reestablish messages!  When we have a
reconnection, we would put the new connection aside, and tell lightningd
to close the current connection: when it did, we would restart
processing of the initial reconnection.

However, we could end up with *multiple* "reconnecting" connections,
while waiting for an existing connection to close.  Though the
connections were long gone, there could still be messages queued
(particularly the channel_reestablish message, which comes early on).

Eventually, a normal reconnection would cause us to process one of
these reconnecting connections, and channeld would see the (perhaps
very old!) messages, and get confused.

(I have a test which triggers this, but it also hangs the connect
 command, due to other issues we will fix in the next release...)

Fixes: #5240
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2022-05-14 14:28:47 +09:30
parent 9039c9c46e
commit 1c495ca5a8
2 changed files with 58 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
connectd/connectd.c
View File

@ -211,36 +211,29 @@ static void peer_connected_in(struct daemon *daemon,
tal_free(connect);
}
/*~ This is an ad-hoc marshalling structure where we store arguments so we
* can call peer_connected again. */
struct peer_reconnected {
struct daemon *daemon;
struct node_id id;
struct wireaddr_internal addr;
const struct wireaddr *remote_addr;
struct crypto_state cs;
const u8 *their_features;
bool incoming;
};
/*~ For simplicity, lightningd only ever deals with a single connection per
* peer. So if we already know about a peer, we tell lightning to disconnect
* the old one and retry once it does. */
static struct io_plan *retry_peer_connected(struct io_conn *conn,
struct peer_reconnected *pr)
{
struct io_plan *plan;
/*~ As you can see, we've had issues with this code before :( */
status_peer_debug(&pr->id, "processing now old peer gone");
/*~ Usually the pattern is to return this directly, but we have to free
* our temporary structure. */
plan = peer_connected(conn, pr->daemon, &pr->id, &pr->addr,
/* If this fails (still waiting), pr will be freed, so reparent onto
* tmpctx so it gets freed either way. */
tal_steal(tmpctx, pr);
/*~ Usually the pattern is to return this directly. */
return peer_connected(conn, pr->daemon, &pr->id, &pr->addr,
pr->remote_addr,
&pr->cs, take(pr->their_features), pr->incoming);
tal_free(pr);
return plan;
}
/*~ A common use for destructors is to remove themselves from a data structure */
static void destroy_peer_reconnected(struct peer_reconnected *pr)
{
peer_reconnected_htable_del(&pr->daemon->reconnected, pr);
}
/*~ If we already know about this peer, we tell lightningd and it disconnects
@ -259,6 +252,13 @@ static struct io_plan *peer_reconnected(struct io_conn *conn,
status_peer_debug(id, "reconnect");
/* If we have a previous reconnection, we replace it. */
pr = peer_reconnected_htable_get(&daemon->reconnected, id);
if (pr) {
peer_reconnected_htable_del(&daemon->reconnected, pr);
tal_free(pr);
}
/* Tell master to kill it: will send peer_disconnect */
msg = towire_connectd_reconnected(NULL, id);
daemon_conn_send(daemon->master, take(msg));
@ -271,6 +271,8 @@ static struct io_plan *peer_reconnected(struct io_conn *conn,
pr->addr = *addr;
pr->remote_addr = tal_dup_or_null(pr, struct wireaddr, remote_addr);
pr->incoming = incoming;
peer_reconnected_htable_add(&daemon->reconnected, pr);
tal_add_destructor(pr, destroy_peer_reconnected);
/*~ Note that tal_dup_talarr() will do handle the take() of features
* (turning it into a simply tal_steal() in those cases). */
@ -280,11 +282,7 @@ static struct io_plan *peer_reconnected(struct io_conn *conn,
* the peer set. When someone calls `io_wake()` on that address, it
* will call retry_peer_connected above. */
return io_wait(conn, peer_htable_get(&daemon->peers, id),
/*~ The notleak() wrapper is a DEVELOPER-mode hack so
* that our memory leak detection doesn't consider 'pr'
* (which is not referenced from our code) to be a
* memory leak. */
retry_peer_connected, notleak(pr));
retry_peer_connected, pr);
}
/*~ When we free a peer, we remove it from the daemon's hashtable */
@ -1981,6 +1979,7 @@ static void dev_connect_memleak(struct daemon *daemon, const u8 *msg)
/* Now delete daemon and those which it has pointers to. */
memleak_remove_region(memtable, daemon, sizeof(daemon));
memleak_remove_htable(memtable, &daemon->peers.raw);
memleak_remove_htable(memtable, &daemon->reconnected.raw);
found_leak = dump_memleak(memtable, memleak_status_broken);
daemon_conn_send(daemon->master,
@ -2127,6 +2126,7 @@ int main(int argc, char *argv[])
/* Allocate and set up our simple top-level structure. */
daemon = tal(NULL, struct daemon);
peer_htable_init(&daemon->peers);
peer_reconnected_htable_init(&daemon->reconnected);
memleak_add_helper(daemon, memleak_daemon_cb);
list_head_init(&daemon->connecting);
timers_init(&daemon->timers, time_mono());

34
connectd/connectd.h
View File

@ -126,6 +126,37 @@ HTABLE_DEFINE_TYPE(struct peer,
peer_eq_node_id,
peer_htable);
/*~ This is an ad-hoc marshalling structure where we store arguments so we
* can call peer_connected again. */
struct peer_reconnected {
struct daemon *daemon;
struct node_id id;
struct wireaddr_internal addr;
const struct wireaddr *remote_addr;
struct crypto_state cs;
const u8 *their_features;
bool incoming;
};
static const struct node_id *
peer_reconnected_keyof(const struct peer_reconnected *pr)
{
return &pr->id;
}
static bool peer_reconnected_eq_node_id(const struct peer_reconnected *pr,
const struct node_id *id)
{
return node_id_eq(&pr->id, id);
}
/*~ This defines 'struct peer_reconnected_htable'. */
HTABLE_DEFINE_TYPE(struct peer_reconnected,
peer_reconnected_keyof,
node_id_hash,
peer_reconnected_eq_node_id,
peer_reconnected_htable);
/*~ This is the global state, like `struct lightningd *ld` in lightningd. */
struct daemon {
/* Who am I? */
@ -142,6 +173,9 @@ struct daemon {
* have disconnected. */
struct peer_htable peers;
/* Peers which have reconnected, waiting for us to kill existing conns */
struct peer_reconnected_htable reconnected;
/* Peers we are trying to reach */
struct list_head connecting;