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channeld: order htlcs by id before retransmission. 

We had one report of this, and then Eugene and Roasbeef of Lightning
Labs confirmed it; they saw misordered HTLCs on reconnection too.

Since we didn't enforce this when we receive HTLCs, we never noticed :(

Fixes: #3920
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Fixed: Protocol: fixed retransmission order of multiple new HTLCs (causing channel close with LND)
This commit is contained in:
Rusty Russell 2020-10-14 16:11:19 +10:30
parent d04597cbb6
commit a3c30441d3
2 changed files with 21 additions and 3 deletions
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22
channeld/channeld.c
View File

@ -15,6 +15,7 @@
#include <bitcoin/psbt.h> #include <bitcoin/psbt.h>
#include <bitcoin/script.h> #include <bitcoin/script.h>
#include <ccan/array_size/array_size.h> #include <ccan/array_size/array_size.h>
#include <ccan/asort/asort.h>
#include <ccan/cast/cast.h> #include <ccan/cast/cast.h>
#include <ccan/container_of/container_of.h> #include <ccan/container_of/container_of.h>
#include <ccan/crypto/hkdf_sha256/hkdf_sha256.h> #include <ccan/crypto/hkdf_sha256/hkdf_sha256.h>
@ -2190,7 +2191,20 @@ static void send_fail_or_fulfill(struct peer *peer, const struct htlc *h)
sync_crypto_write(peer->pps, take(msg)); sync_crypto_write(peer->pps, take(msg));
} }
static void resend_commitment(struct peer *peer, const struct changed_htlc *last) static int cmp_changed_htlc_id(const struct changed_htlc *a,
const struct changed_htlc *b,
void *unused)
{
/* ids can be the same (sender and receiver are indep) but in
* that case we don't care about order. */
if (a->id > b->id)
return 1;
else if (a->id < b->id)
return -1;
return 0;
}
static void resend_commitment(struct peer *peer, struct changed_htlc *last)
{ {
size_t i; size_t i;
struct bitcoin_signature commit_sig, *htlc_sigs; struct bitcoin_signature commit_sig, *htlc_sigs;
@ -2204,6 +2218,12 @@ static void resend_commitment(struct peer *peer, const struct changed_htlc *last
channel_feerate(peer->channel, LOCAL), channel_feerate(peer->channel, LOCAL),
channel_feerate(peer->channel, REMOTE)); channel_feerate(peer->channel, REMOTE));
/* Note that HTLCs must be *added* in order. Simplest thing to do
* is to sort them all into ascending ID order here (we could do
* this when we save them in channel_sending_commit, but older versions
* won't have them sorted in the db, so doing it here is better). */
asort(last, tal_count(last), cmp_changed_htlc_id, NULL);
/* BOLT #2: /* BOLT #2:
* *
* - if `next_commitment_number` is equal to the commitment * - if `next_commitment_number` is equal to the commitment

2
tests/test_connection.py
View File

@ -2193,7 +2193,6 @@ def test_dataloss_protection(node_factory, bitcoind):
assert (closetxid, "confirmed") in set([(o['txid'], o['status']) for o in l2.rpc.listfunds()['outputs']]) assert (closetxid, "confirmed") in set([(o['txid'], o['status']) for o in l2.rpc.listfunds()['outputs']])
@unittest.skip("Broken")
@unittest.skipIf(not DEVELOPER, "needs dev_disconnect") @unittest.skipIf(not DEVELOPER, "needs dev_disconnect")
def test_restart_multi_htlc_rexmit(node_factory, bitcoind, executor): def test_restart_multi_htlc_rexmit(node_factory, bitcoind, executor):
# l1 disables commit timer once we send first htlc, dies on commit # l1 disables commit timer once we send first htlc, dies on commit
@ -2663,7 +2662,6 @@ def test_connection_timeout(node_factory):
l1.daemon.wait_for_log('conn timed out') l1.daemon.wait_for_log('conn timed out')
@unittest.skip("Broken")
@unittest.skipIf(not DEVELOPER, "needs --dev-disconnect") @unittest.skipIf(not DEVELOPER, "needs --dev-disconnect")
def test_htlc_retransmit_order(node_factory, executor): def test_htlc_retransmit_order(node_factory, executor):
NUM_HTLCS = 10 NUM_HTLCS = 10