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#include <bitcoin/feerate.h>
#include <bitcoin/script.h>
#include <closingd/gen_closing_wire.h>
#include <common/close_tx.h>
#include <common/initial_commit_tx.h>
#include <common/per_peer_state.h>
#include <common/utils.h>
#include <errno.h>
#include <gossipd/gen_gossip_wire.h>
#include <inttypes.h>
#include <lightningd/chaintopology.h>
#include <lightningd/channel.h>
#include <lightningd/closing_control.h>
#include <lightningd/hsm_control.h>
#include <lightningd/lightningd.h>
#include <lightningd/log.h>
#include <lightningd/options.h>
#include <lightningd/peer_control.h>
#include <lightningd/subd.h>
static struct amount_sat calc_tx_fee(struct amount_sat sat_in,
const struct bitcoin_tx *tx)
{
struct amount_sat amt, fee = sat_in;
for (size_t i = 0; i < tx->wtx->num_outputs; i++) {
amt = bitcoin_tx_output_get_amount(tx, i);
if (!amount_sat_sub(&fee, fee, amt))
fatal("Tx spends more than input %s? %s",
type_to_string(tmpctx, struct amount_sat, &sat_in),
type_to_string(tmpctx, struct bitcoin_tx, tx));
}
return fee;
}
/* Is this better than the last tx we were holding? This can happen
* even without closingd misbehaving, if we have multiple,
* interrupted, rounds of negotiation. */
static bool better_closing_fee(struct lightningd *ld,
struct channel *channel,
const struct bitcoin_tx *tx)
{
struct amount_sat fee, last_fee, min_fee;
u64 weight;
u32 min_feerate;
bool feerate_unknown;
/* Calculate actual fee (adds in eliminated outputs) */
fee = calc_tx_fee(channel->funding, tx);
last_fee = calc_tx_fee(channel->funding, channel->last_tx);
log_debug(channel->log, "Their actual closing tx fee is %s"
" vs previous %s",
type_to_string(tmpctx, struct amount_sat, &fee),
type_to_string(tmpctx, struct amount_sat, &last_fee));
/* Weight once we add in sigs. */
weight = measure_tx_weight(tx) + 74 * 2;
/* If we don't have a feerate estimate, this gives feerate_floor */
min_feerate = feerate_min(ld, &feerate_unknown);
min_fee = amount_tx_fee(min_feerate, weight);
if (amount_sat_less(fee, min_fee)) {
log_debug(channel->log, "... That's below our min %s"
" for weight %"PRIu64" at feerate %u",
type_to_string(tmpctx, struct amount_sat, &fee),
weight, min_feerate);
return false;
}
/* In case of a tie, prefer new over old: this covers the preference
* for a mutual close over a unilateral one. */
/* If we don't know the feerate, prefer higher fee. */
if (feerate_unknown)
return amount_sat_greater_eq(fee, last_fee);
/* Otherwise prefer lower fee. */
return amount_sat_less_eq(fee, last_fee);
}
static void peer_received_closing_signature(struct channel *channel,
const u8 *msg)
{
struct bitcoin_signature sig;
struct bitcoin_tx *tx;
struct bitcoin_txid tx_id;
struct lightningd *ld = channel->peer->ld;
if (!fromwire_closing_received_signature(msg, msg, &sig, &tx)) {
channel_internal_error(channel, "Bad closing_received_signature %s",
tal_hex(msg, msg));
return;
}
tx->chainparams = get_chainparams(channel->peer->ld);
/* FIXME: Make sure signature is correct! */
if (better_closing_fee(ld, channel, tx)) {
channel_set_last_tx(channel, tx, &sig, TX_CHANNEL_CLOSE);
wallet_channel_save(ld->wallet, channel);
}
// Send back the txid so we can update the billboard on selection.
bitcoin_txid(channel->last_tx, &tx_id);
/* OK, you can continue now. */
subd_send_msg(channel->owner,
take(towire_closing_received_signature_reply(channel, &tx_id)));
}
static void peer_closing_complete(struct channel *channel, const u8 *msg)
{
if (!fromwire_closing_complete(msg)) {
channel_internal_error(channel, "Bad closing_complete %s",
tal_hex(msg, msg));
return;
}
/* Don't report spurious failure when closingd exits. */
channel_set_owner(channel, NULL);
/* Clear any transient negotiation messages */
channel_set_billboard(channel, false, NULL);
/* Retransmission only, ignore closing. */
if (channel->state == CLOSINGD_COMPLETE)
return;
/* Channel gets dropped to chain cooperatively. */
drop_to_chain(channel->peer->ld, channel, true);
channel_set_state(channel, CLOSINGD_SIGEXCHANGE, CLOSINGD_COMPLETE);
}
static unsigned closing_msg(struct subd *sd, const u8 *msg, const int *fds UNUSED)
{
enum closing_wire_type t = fromwire_peektype(msg);
switch (t) {
case WIRE_CLOSING_RECEIVED_SIGNATURE:
peer_received_closing_signature(sd->channel, msg);
break;
case WIRE_CLOSING_COMPLETE:
peer_closing_complete(sd->channel, msg);
break;
/* We send these, not receive them */
case WIRE_CLOSING_INIT:
case WIRE_CLOSING_RECEIVED_SIGNATURE_REPLY:
break;
}
return 0;
}
void peer_start_closingd(struct channel *channel,
struct per_peer_state *pps,
bool reconnected,
const u8 *channel_reestablish)
{
u8 *initmsg;
u32 feerate;
struct amount_sat minfee, startfee, feelimit;
u64 num_revocations;
struct amount_msat their_msat;
int hsmfd;
struct secret last_remote_per_commit_secret;
struct lightningd *ld = channel->peer->ld;
if (!channel->remote_shutdown_scriptpubkey) {
channel_internal_error(channel,
"Can't start closing: no remote info");
return;
}
hsmfd = hsm_get_client_fd(ld, &channel->peer->id, channel->dbid,
HSM_CAP_SIGN_CLOSING_TX
| HSM_CAP_COMMITMENT_POINT);
channel_set_owner(channel,
new_channel_subd(ld,
"lightning_closingd",
channel, channel->log, true,
closing_wire_type_name, closing_msg,
channel_errmsg,
channel_set_billboard,
take(&pps->peer_fd),
take(&pps->gossip_fd),
take(&pps->gossip_store_fd),
take(&hsmfd),
NULL));
if (!channel->owner) {
log_unusual(channel->log, "Could not subdaemon closing: %s",
strerror(errno));
channel_fail_reconnect_later(channel,
"Failed to subdaemon closing");
return;
}
/* BOLT #2:
*
* The sending node:
* - MUST set `fee_satoshis` less than or equal to the base
* fee of the final commitment transaction, as calculated in
* [BOLT #3](03-transactions.md#fee-calculation).
*/
feelimit = commit_tx_base_fee(channel->channel_info.feerate_per_kw[LOCAL],
0);
/* Pick some value above slow feerate (or min possible if unknown) */
minfee = commit_tx_base_fee(feerate_min(ld, NULL), 0);
/* If we can't determine feerate, start at half unilateral feerate. */
feerate = mutual_close_feerate(ld->topology);
if (!feerate) {
feerate = channel->channel_info.feerate_per_kw[LOCAL] / 2;
if (feerate < feerate_floor())
feerate = feerate_floor();
}
startfee = commit_tx_base_fee(feerate, 0);
if (amount_sat_greater(startfee, feelimit))
startfee = feelimit;
if (amount_sat_greater(minfee, feelimit))
minfee = feelimit;
num_revocations
= revocations_received(&channel->their_shachain.chain);
/* BOLT #3:
*
* Each node offering a signature:
* - MUST round each output down to whole satoshis.
*/
/* What is not ours is theirs */
if (!amount_sat_sub_msat(&their_msat,
channel->funding, channel->our_msat)) {
log_broken(channel->log, "our_msat overflow funding %s minus %s",
type_to_string(tmpctx, struct amount_sat,
&channel->funding),
type_to_string(tmpctx, struct amount_msat,
&channel->our_msat));
channel_fail_permanent(channel, "our_msat overflow on closing");
return;
}
/* BOLT #2:
*
* - if it supports `option_data_loss_protect`:
*...
* - if `next_revocation_number` equals 0:
* - MUST set `your_last_per_commitment_secret` to all zeroes
* - otherwise:
* - MUST set `your_last_per_commitment_secret` to the last
* `per_commitment_secret` it received
*/
if (num_revocations == 0)
memset(&last_remote_per_commit_secret, 0,
sizeof(last_remote_per_commit_secret));
else if (!shachain_get_secret(&channel->their_shachain.chain,
num_revocations-1,
&last_remote_per_commit_secret)) {
channel_fail_permanent(channel,
"Could not get revocation secret %"PRIu64,
num_revocations-1);
return;
}
initmsg = towire_closing_init(tmpctx,
&get_chainparams(ld)->genesis_blockhash,
pps,
&channel->funding_txid,
channel->funding_outnum,
channel->funding,
&channel->local_funding_pubkey,
&channel->channel_info.remote_fundingkey,
channel->funder,
amount_msat_to_sat_round_down(channel->our_msat),
amount_msat_to_sat_round_down(their_msat),
channel->our_config.dust_limit,
minfee, feelimit, startfee,
p2wpkh_for_keyidx(tmpctx, ld,
channel->final_key_idx),
channel->remote_shutdown_scriptpubkey,
reconnected,
channel->next_index[LOCAL],
channel->next_index[REMOTE],
num_revocations,
channel_reestablish,
p2wpkh_for_keyidx(tmpctx, ld,
channel->final_key_idx),
&last_remote_per_commit_secret);
/* We don't expect a response: it will give us feedback on
* signatures sent and received, then closing_complete. */
subd_send_msg(channel->owner, take(initmsg));
/* Now tell gossipd that we're closing and that neither direction should
* be used. */
if (channel->scid)
subd_send_msg(channel->peer->ld->gossip,
take(towire_gossip_local_channel_close(
tmpctx, channel->scid)));
}