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channeld: don't ever send back-to-back feerate changes.

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There are several reports of desynchronization with LND here; a simple
approach is to only have one feerate change in flight at any time.

Even if this turns out to be our fault, it's been a historic area of
confusion, so this restriction seems reasonable.

Changelog-Fixed: Protocol: Don't create more than one feerate change at a time, as this seems to desync with LND.
Fixes: #4152
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2021-04-21 15:54:26 +09:30
parent e3d1115598
commit e64e6ba283
3 changed files with 45 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
channeld/channeld.c
View File

@@ -944,6 +944,28 @@ static struct bitcoin_signature *unraw_sigs(const tal_t *ctx,
return sigs;
}
/* Do we want to update fees? */
static bool want_fee_update(const struct peer *peer, u32 *target)
{
u32 max, val;
if (peer->channel->opener != LOCAL)
return false;
max = approx_max_feerate(peer->channel);
val = peer->desired_feerate;
/* FIXME: We should avoid adding HTLCs until we can meet this
* feerate! */
if (val > max)
val = max;
if (target)
*target = val;
return val != channel_feerate(peer->channel, REMOTE);
}
static void send_commit(struct peer *peer)
{
u8 *msg;
@@ -954,6 +976,7 @@ static void send_commit(struct peer *peer)
const struct htlc **htlc_map;
struct wally_tx_output *direct_outputs[NUM_SIDES];
struct penalty_base *pbase;
u32 feerate_target;
#if DEVELOPER
/* Hack to suppress all commit sends if dev_disconnect says to */
@@ -1002,27 +1025,21 @@ static void send_commit(struct peer *peer)
}
/* If we wanted to update fees, do it now. */
if (peer->channel->opener == LOCAL) {
u32 feerate, max = approx_max_feerate(peer->channel);
feerate = peer->desired_feerate;
/* FIXME: We should avoid adding HTLCs until we can meet this
* feerate! */
if (feerate > max)
feerate = max;
if (feerate != channel_feerate(peer->channel, REMOTE)) {
if (want_fee_update(peer, &feerate_target)) {
/* FIXME: We occasionally desynchronize with LND here, so
* don't stress things by having more than one feerate change
* in-flight! */
if (feerate_changes_done(peer->channel->fee_states)) {
u8 *msg;
if (!channel_update_feerate(peer->channel, feerate))
if (!channel_update_feerate(peer->channel, feerate_target))
status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Could not afford feerate %u"
" (vs max %u)",
feerate, max);
feerate_target, approx_max_feerate(peer->channel));
msg = towire_update_fee(NULL, &peer->channel_id,
feerate);
feerate_target);
sync_crypto_write(peer->pps, take(msg));
}
}

10
common/fee_states.c
View File

@@ -73,6 +73,16 @@ u32 get_feerate(const struct fee_states *fee_states,
abort();
}
/* Are feerates all agreed by both sides? */
bool feerate_changes_done(const struct fee_states *fee_states)
{
size_t num_feerates = 0;
for (size_t i = 0; i < ARRAY_SIZE(fee_states->feerate); i++) {
num_feerates += (fee_states->feerate[i] != NULL);
}
return num_feerates == 1;
}
void start_fee_update(struct fee_states *fee_states,
enum side opener,
u32 feerate_per_kw)

4
common/fee_states.h
View File

@@ -85,4 +85,8 @@ struct fee_states *fromwire_fee_states(const tal_t *ctx,
* Is this fee_state struct valid for this side?
*/
bool fee_states_valid(const struct fee_states *fee_states, enum side opener);
/* Are therre no more fee changes in-flight? */
bool feerate_changes_done(const struct fee_states *fee_states);
#endif /* LIGHTNING_COMMON_FEE_STATES_H */