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channeld: allow remote node to exceed their own HTLC count limits.

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We try not to exceed either side, but the spec still allows them to
(we don't, but older nodes would have, as could other implementations).

Fixes: #3953
Changelog-Fixed: protocol: overzealous close when peer sent more HTLCs than they'd told us we could send.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2021-03-16 11:15:09 +10:30
parent a7af106321
commit 3fd22f86df
1 changed files with 11 additions and 9 deletions
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20
channeld/full_channel.c
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@@ -489,7 +489,6 @@ static enum channel_add_err add_htlc(struct channel *channel,
enum side sender = htlc_state_owner(state), recipient = !sender; enum side sender = htlc_state_owner(state), recipient = !sender;
const struct htlc **committed, **adding, **removing; const struct htlc **committed, **adding, **removing;
const struct channel_view *view; const struct channel_view *view;
u32 min_concurrent_htlcs;
htlc = tal(tmpctx, struct htlc); htlc = tal(tmpctx, struct htlc);
@@ -573,16 +572,19 @@ static enum channel_add_err add_htlc(struct channel *channel,
* HTLCs to its local commitment transaction... * HTLCs to its local commitment transaction...
* - SHOULD fail the channel. * - SHOULD fail the channel.
*/ */
/* Also we should not add more htlc's than sender or recipient if (tal_count(committed) - tal_count(removing) + tal_count(adding)
* configured. This mitigates attacks in which a peer can force the > channel->config[recipient].max_accepted_htlcs) {
* opener of the channel to pay unnecessary onchain fees during a fee return CHANNEL_ERR_TOO_MANY_HTLCS;
}
/* Also *we* should not add more htlc's we configured. This
* mitigates attacks in which a peer can force the opener of
* the channel to pay unnecessary onchain fees during a fee
* spike with large commitment transactions. * spike with large commitment transactions.
*/ */
min_concurrent_htlcs = channel->config[recipient].max_accepted_htlcs; if (sender == LOCAL
if (min_concurrent_htlcs > channel->config[sender].max_accepted_htlcs) && tal_count(committed) - tal_count(removing) + tal_count(adding)
min_concurrent_htlcs = channel->config[sender].max_accepted_htlcs; > channel->config[LOCAL].max_accepted_htlcs) {
if (tal_count(committed) - tal_count(removing) + tal_count(adding)
> min_concurrent_htlcs) {
return CHANNEL_ERR_TOO_MANY_HTLCS; return CHANNEL_ERR_TOO_MANY_HTLCS;
} }