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fix: calc commit_txfee_spend/recv for spendable or receivable

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This commit is contained in:
Michael Schmoock 2020-03-08 14:39:32 +01:00 committed by Christian Decker
parent 33c8afea80
commit ed56b22094
1 changed files with 64 additions and 4 deletions
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68
lightningd/peer_control.c
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@ -509,9 +509,10 @@ static void json_add_sat_only(struct json_stream *result,
type_to_string(tmpctx, struct amount_msat, &msat));
}
/* Fee a commitment transaction would currently cost when spending */
/* This is quite a lot of work to figure out what it would cost us! */
static struct amount_sat commit_txfee(const struct channel *channel,
struct amount_msat spendable)
static struct amount_sat commit_txfee_spend(const struct channel *channel,
struct amount_msat spendable)
{
/* FIXME: make per-channel htlc maps! */
const struct htlc_in *hin;
@ -567,6 +568,65 @@ static struct amount_sat commit_txfee(const struct channel *channel,
return commit_tx_base_fee(local_feerate * 2, num_untrimmed_htlcs + 1);
}
/* Fee a commitment transaction would currently cost when receiving */
static struct amount_sat commit_txfee_recv(const struct channel *channel,
struct amount_msat receivable)
{
/* FIXME: make per-channel htlc maps! */
const struct htlc_in *hin;
struct htlc_in_map_iter ini;
const struct htlc_out *hout;
struct htlc_out_map_iter outi;
struct lightningd *ld = channel->peer->ld;
u32 feerate = get_feerate(channel->channel_info.fee_states,
channel->funder, REMOTE);
size_t num_untrimmed_htlcs = 0;
/* Assume we tried to receive "receivable" */
if (!htlc_is_trimmed(REMOTE, receivable, feerate,
channel->channel_info.their_config.dust_limit,
REMOTE))
num_untrimmed_htlcs++;
for (hin = htlc_in_map_first(&ld->htlcs_in, &ini);
hin;
hin = htlc_in_map_next(&ld->htlcs_in, &ini)) {
if (hin->key.channel != channel)
continue;
if (!htlc_is_trimmed(LOCAL, hin->msat, feerate,
channel->channel_info.their_config.dust_limit,
REMOTE))
num_untrimmed_htlcs++;
}
for (hout = htlc_out_map_first(&ld->htlcs_out, &outi);
hout;
hout = htlc_out_map_next(&ld->htlcs_out, &outi)) {
if (hout->key.channel != channel)
continue;
if (!htlc_is_trimmed(REMOTE, hout->msat, feerate,
channel->channel_info.their_config.dust_limit,
REMOTE))
num_untrimmed_htlcs++;
}
/*
* BOLT-95c74fef2fe590cb8adbd7b848743a229ffe825a #2:
* Adding an HTLC: update_add_htlc
*
* A sending node:
* - if it is responsible for paying the Bitcoin fee:
* - SHOULD NOT offer `amount_msat` if, after adding that HTLC to
* its commitment transaction, its remaining balance doesn't allow
* it to pay the fee for a future additional non-dust HTLC at
* `N*feerate_per_kw` while maintaining its channel reserve
* ("fee spike buffer"), where `N` is a parameter chosen by the
* implementation (`N = 2` is recommended to ensure
* predictability).
*/
return commit_tx_base_fee(2 * feerate, num_untrimmed_htlcs + 1);
}
static void subtract_offered_htlcs(const struct channel *channel,
struct amount_msat *amount)
{
@ -733,7 +793,7 @@ static void json_add_channel(struct lightningd *ld,
/* If we're funder, subtract txfees we'll need to spend this */
if (channel->funder == LOCAL) {
if (!amount_msat_sub_sat(&spendable, spendable,
commit_txfee(channel, spendable)))
commit_txfee_spend(channel, spendable)))
spendable = AMOUNT_MSAT(0);
}
@ -764,7 +824,7 @@ static void json_add_channel(struct lightningd *ld,
/* If they're funder, subtract txfees they'll need to spend this */
if (channel->funder == REMOTE) {
if (!amount_msat_sub_sat(&receivable, receivable,
commit_txfee(channel, receivable)))
commit_txfee_recv(channel, receivable)))
receivable = AMOUNT_MSAT(0);
}