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closingd: send the tx to master as we negotiate.

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We can derive fees from this, and also broadcast at any time without
having to reconstruct it.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2017-08-18 14:13:52 +09:30
parent 253b3e679e
commit c389215a35
6 changed files with 87 additions and 127 deletions
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166
lightningd/peer_control.c
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@@ -97,7 +97,44 @@ static void peer_reconnect(struct peer *peer)
static void drop_to_chain(struct peer *peer)
{
const tal_t *tmpctx = tal_tmpctx(peer);
u8 *funding_wscript;
struct pubkey local_funding_pubkey;
struct secrets secrets;
secp256k1_ecdsa_signature sig;
/* FIXME: Implement. */
if (peer->state != CLOSINGD_SIGEXCHANGE) {
tal_free(tmpctx);
return;
}
derive_basepoints(peer->seed, &local_funding_pubkey, NULL, &secrets,
NULL);
funding_wscript = bitcoin_redeem_2of2(tmpctx,
&local_funding_pubkey,
&peer->channel_info->remote_fundingkey);
/* Need input amount for signing */
peer->last_tx->input[0].amount = tal_dup(peer->last_tx->input, u64,
&peer->funding_satoshi);
sign_tx_input(peer->last_tx, 0, NULL, funding_wscript,
&secrets.funding_privkey,
&local_funding_pubkey,
&sig);
peer->last_tx->input[0].witness
= bitcoin_witness_2of2(peer->last_tx->input,
peer->last_sig,
&sig,
&peer->channel_info->remote_fundingkey,
&local_funding_pubkey);
/* Keep broadcasting until we say stop (can fail due to dup,
* if they beat us to the broadcast). */
broadcast_tx(peer->ld->topology, peer, peer->last_tx, NULL);
tal_free(tmpctx);
}
void peer_fail_permanent(struct peer *peer, const u8 *msg)
@@ -500,7 +537,6 @@ void add_peer(struct lightningd *ld, u64 unique_id,
= peer->num_revocations_received = 0;
peer->next_htlc_id = 0;
wallet_shachain_init(ld->wallet, &peer->their_shachain);
peer->closing_sig_received = NULL;
idname = type_to_string(peer, struct pubkey, id);
@@ -1240,39 +1276,57 @@ static int closingd_got_negotiation_error(struct peer *peer, const u8 *msg)
return -1;
}
static bool better_closing_fee(struct peer *peer, u64 fee_satoshi)
void peer_last_tx(struct peer *peer, struct bitcoin_tx *tx,
const secp256k1_ecdsa_signature *sig)
{
/* FIXME: Use estimatefee 24 or something? */
u64 min_feerate = get_feerate(peer->ld->topology) / 2;
/* FIXME: Real fee, using real tx, and estimatefee 6 */
u64 ideal_fee = commit_tx_base_fee(get_feerate(peer->ld->topology), 0);
s64 old_diff, new_diff;
/* FIXME: save to db. */
/* FIXME: Use real tx here! (+ 74 for sig). */
if (fee_satoshi < commit_tx_base_fee(min_feerate, 0))
tal_free(peer->last_sig);
peer->last_sig = tal_dup(peer, secp256k1_ecdsa_signature, sig);
tal_free(peer->last_tx);
peer->last_tx = tal_steal(peer, tx);
}
/* Is this better than the last tx we were holding? */
static bool better_closing_fee(struct peer *peer, const struct bitcoin_tx *tx)
{
u64 weight, fee, last_fee, ideal_fee, min_fee;
s64 old_diff, new_diff;
size_t i;
/* Calculate actual fee. */
fee = peer->funding_satoshi;
for (i = 0; i < tal_count(tx->output); i++)
fee -= tx->output[i].amount;
last_fee = peer->funding_satoshi;
for (i = 0; i < tal_count(peer->last_tx); i++)
last_fee -= peer->last_tx->output[i].amount;
/* Weight once we add in sigs. */
weight = measure_tx_cost(tx) + 74 * 2;
/* FIXME: Use estimatefee 24 or something? */
min_fee = get_feerate(peer->ld->topology) / 5 * weight / 1000;
if (fee < min_fee)
return false;
/* FIXME: Derive old fee from last tx, which would work even
* for the case where we're using the final commitment tx. */
if (!peer->closing_sig_received)
return true;
/* FIXME: Real fee, using real tx, and estimatefee 6 */
/* FIXME: Use estimatefee 6 */
ideal_fee = get_feerate(peer->ld->topology) / 2 * weight / 1000;
/* We prefer fee which is closest to our ideal. */
old_diff = imaxabs((s64)ideal_fee - (s64)peer->closing_fee_received);
new_diff = imaxabs((s64)ideal_fee - (s64)fee_satoshi);
old_diff = imaxabs((s64)ideal_fee - (s64)last_fee);
new_diff = imaxabs((s64)ideal_fee - (s64)fee);
return (new_diff < old_diff);
}
static int peer_received_closing_signature(struct peer *peer, const u8 *msg)
{
u64 fee_satoshi;
secp256k1_ecdsa_signature sig;
struct bitcoin_tx *tx = tal(msg, struct bitcoin_tx);
if (!fromwire_closing_received_signature(msg, NULL,
&fee_satoshi, &sig)) {
if (!fromwire_closing_received_signature(msg, NULL, &sig, tx)) {
peer_internal_error(peer, "Bad closing_received_signature %s",
tal_hex(peer, msg));
return -1;
@@ -1280,14 +1334,8 @@ static int peer_received_closing_signature(struct peer *peer, const u8 *msg)
/* FIXME: Make sure signature is correct! */
if (better_closing_fee(peer, fee_satoshi)) {
/* FIXME: save to db. */
peer->closing_fee_received = fee_satoshi;
tal_free(peer->closing_sig_received);
peer->closing_sig_received
= tal_dup(peer, secp256k1_ecdsa_signature, &sig);
}
if (better_closing_fee(peer, tx))
peer_last_tx(peer, tx, &sig);
/* OK, you can continue now. */
subd_send_msg(peer->owner,
@@ -1297,13 +1345,6 @@ static int peer_received_closing_signature(struct peer *peer, const u8 *msg)
static int peer_closing_complete(struct peer *peer, const u8 *msg)
{
struct bitcoin_tx *tx;
u8 *local_scriptpubkey, *funding_wscript;
u64 out_amounts[NUM_SIDES];
struct pubkey local_funding_pubkey;
struct secrets secrets;
secp256k1_ecdsa_signature sig;
if (!fromwire_closing_complete(msg, NULL)) {
peer_internal_error(peer, "Bad closing_complete %s",
tal_hex(peer, msg));
@@ -1314,60 +1355,7 @@ static int peer_closing_complete(struct peer *peer, const u8 *msg)
if (peer->state == CLOSINGD_COMPLETE)
return -1;
if (!peer->closing_sig_received) {
peer_internal_error(peer,
"closing_complete without sending sig!");
return -1;
}
local_scriptpubkey = p2wpkh_for_keyidx(msg, peer->ld,
peer->local_shutdown_idx);
if (!local_scriptpubkey) {
peer_internal_error(peer,
"Can't generate local shutdown scriptpubkey");
return -1;
}
/* BOLT #3:
*
* The amounts for each output MUST BE rounded down to whole satoshis.
*/
out_amounts[LOCAL] = *peer->our_msatoshi / 1000;
out_amounts[REMOTE] = peer->funding_satoshi
- (*peer->our_msatoshi / 1000);
out_amounts[peer->funder] -= peer->closing_fee_received;
derive_basepoints(peer->seed, &local_funding_pubkey, NULL, &secrets,
NULL);
tx = create_close_tx(msg, local_scriptpubkey,
peer->remote_shutdown_scriptpubkey,
peer->funding_txid,
peer->funding_outnum,
peer->funding_satoshi,
out_amounts[LOCAL],
out_amounts[REMOTE],
peer->our_config.dust_limit_satoshis);
funding_wscript = bitcoin_redeem_2of2(msg,
&local_funding_pubkey,
&peer->channel_info->remote_fundingkey);
sign_tx_input(tx, 0, NULL, funding_wscript,
&secrets.funding_privkey,
&local_funding_pubkey,
&sig);
tx->input[0].witness
= bitcoin_witness_2of2(tx->input,
peer->closing_sig_received,
&sig,
&peer->channel_info->remote_fundingkey,
&local_funding_pubkey);
/* Keep broadcasting until we say stop (can fail due to dup,
* if they beat us to the broadcast). */
broadcast_tx(peer->ld->topology, peer, tx, NULL);
drop_to_chain(peer);
peer_set_condition(peer, CLOSINGD_SIGEXCHANGE, CLOSINGD_COMPLETE);
return -1;
}