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splice: Fixes from splice-out test
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Added a test for splicing out that exposed some behavior and code glitches that are addressed in this commit.

Added test for splice gossip.

Also added documentation for how to do a splice out.

ChangeLog-Fixed: Added docs, testing, and some fixes related to splicing out, insufficent balance handling, and restarting during a splice.
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@ddustin @rustyrussell
ddustin authored and rustyrussell committed Sep 21, 2023
1 parent f60882f commit 0a5ef7f
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Showing 6 changed files with 255 additions and 121 deletions.
154 changes: 85 additions & 69 deletions channeld/channeld.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,8 @@
((msg) == WIRE_SPLICE || \
(msg) == WIRE_SPLICE_ACK)

#define SAT_MIN(a, b) (amount_sat_less((a), (b)) ? (a) : (b))

struct peer {
struct per_peer_state *pps;
bool channel_ready[NUM_SIDES];
Expand Down Expand Up @@ -756,6 +758,9 @@ static void check_mutual_splice_locked(struct peer *peer)
&inflight->outpoint.txid);
wire_sync_write(MASTER_FD, take(msg));

/* We must regossip the scid since it has changed */
peer->gossip_scid_announced = false;

channel_announcement_negotiate(peer);
billboard_update(peer);
send_channel_update(peer, 0);
Expand Down Expand Up @@ -1487,7 +1492,8 @@ static u8 *send_commit_part(struct peer *peer,
const struct htlc **changed_htlcs,
bool notify_master,
s64 splice_amnt,
s64 remote_splice_amnt)
s64 remote_splice_amnt,
u64 remote_index)
{
u8 *msg;
struct bitcoin_signature commit_sig, *htlc_sigs;
Expand Down Expand Up @@ -1515,14 +1521,14 @@ static u8 *send_commit_part(struct peer *peer,
txs = channel_splice_txs(tmpctx, funding, funding_sats, &htlc_map,
direct_outputs, &funding_wscript,
peer->channel, &peer->remote_per_commit,
peer->next_index[REMOTE], REMOTE,
remote_index, REMOTE,
splice_amnt, remote_splice_amnt);
htlc_sigs =
calc_commitsigs(tmpctx, peer, txs, funding_wscript, htlc_map,
peer->next_index[REMOTE], &commit_sig);
remote_index, &commit_sig);

if (direct_outputs[LOCAL] != NULL) {
pbase = penalty_base_new(tmpctx, peer->next_index[REMOTE],
pbase = penalty_base_new(tmpctx, remote_index,
txs[0], direct_outputs[LOCAL]);

/* Add the penalty_base to our in-memory list as well, so we
Expand All @@ -1543,8 +1549,7 @@ static u8 *send_commit_part(struct peer *peer,
status_debug("Telling master we're about to commit...");
/* Tell master to save this next commit to database, then wait.
*/
msg = sending_commitsig_msg(NULL, peer->next_index[REMOTE],
pbase,
msg = sending_commitsig_msg(NULL, remote_index, pbase,
peer->channel->fee_states,
peer->channel->blockheight_states,
changed_htlcs,
Expand Down Expand Up @@ -1692,7 +1697,7 @@ static void send_commit(struct peer *peer)

msgs[0] = send_commit_part(peer, &peer->channel->funding,
peer->channel->funding_sats, changed_htlcs,
true, 0, 0);
true, 0, 0, peer->next_index[REMOTE]);

/* Loop over current inflights
* BOLT-0d8b701614b09c6ee4172b04da2203e73deec7e2 #2:
Expand All @@ -1715,7 +1720,8 @@ static void send_commit(struct peer *peer)
peer->splice_state->inflights[i]->amnt,
changed_htlcs, false,
peer->splice_state->inflights[i]->splice_amnt,
remote_splice_amnt));
remote_splice_amnt,
peer->next_index[REMOTE]));
}

peer->next_index[REMOTE]++;
Expand Down Expand Up @@ -2907,7 +2913,7 @@ static size_t calc_weight(enum tx_role role, const struct wally_psbt *psbt)
weight += psbt_input_get_weight(psbt, i);

for (size_t i = 0; i < psbt->num_outputs; i++)
if (is_initiators_serial(&psbt->inputs[i].unknowns)) {
if (is_initiators_serial(&psbt->outputs[i].unknowns)) {
if (role == TX_INITIATOR)
weight += psbt_output_get_weight(psbt, i);
}
Expand All @@ -2928,7 +2934,7 @@ static struct amount_sat check_balances(struct peer *peer,
{
struct amount_sat min_initiator_fee, min_accepter_fee,
max_initiator_fee, max_accepter_fee,
funding_amount_res;
funding_amount_res, min_multiplied;
struct amount_msat funding_amount,
initiator_fee, accepter_fee;
struct amount_msat in[NUM_TX_ROLES], out[NUM_TX_ROLES];
Expand Down Expand Up @@ -2977,45 +2983,23 @@ static struct amount_sat check_balances(struct peer *peer,
* While we're, here, adjust the output counts by splice amount.
*/

if(peer->splicing->opener_relative > 0) {
if (!amount_msat_add_sat(&funding_amount, funding_amount,
amount_sat((u64)peer->splicing->opener_relative)))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to add opener funding");
if (!amount_msat_add_sat(&out[TX_INITIATOR], out[TX_INITIATOR],
amount_sat((u64)peer->splicing->opener_relative)))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to add opener funding to out amnt.");
} else {
if (!amount_msat_sub_sat(&funding_amount, funding_amount,
amount_sat((u64)-peer->splicing->opener_relative)))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to sub opener funding");
if (!amount_msat_sub_sat(&out[TX_INITIATOR], out[TX_INITIATOR],
amount_sat((u64)peer->splicing->opener_relative)))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to sub opener funding from out amnt.");
}
if (!amount_msat_add_sat_s64(&funding_amount, funding_amount,
peer->splicing->opener_relative))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to add opener funding");
if (!amount_msat_add_sat_s64(&out[TX_INITIATOR], out[TX_INITIATOR],
peer->splicing->opener_relative))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to add opener funding to out amnt.");

if(peer->splicing->accepter_relative > 0) {
if (!amount_msat_add_sat(&funding_amount, funding_amount,
amount_sat((u64)peer->splicing->accepter_relative)))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to add accepter funding");
if (!amount_msat_add_sat(&out[TX_ACCEPTER], out[TX_ACCEPTER],
amount_sat((u64)peer->splicing->accepter_relative)))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to add accepter funding to out amnt.");
} else {
if (!amount_msat_sub_sat(&funding_amount, funding_amount,
amount_sat((u64)-peer->splicing->accepter_relative)))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to subtract accepter funding");
if (!amount_msat_sub_sat(&out[TX_ACCEPTER], out[TX_ACCEPTER],
amount_sat((u64)-peer->splicing->accepter_relative)))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to sub accepter funding from out amnt.");
}
if (!amount_msat_add_sat_s64(&funding_amount, funding_amount,
peer->splicing->accepter_relative))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to add accepter funding");
if (!amount_msat_add_sat_s64(&out[TX_ACCEPTER], out[TX_ACCEPTER],
peer->splicing->accepter_relative))
peer_failed_warn(peer->pps, &peer->channel_id,
"Unable to add accepter funding to out amnt.");

if (amount_msat_less(in[TX_INITIATOR], out[TX_INITIATOR])) {
msg = towire_channeld_splice_funding_error(NULL, in[TX_INITIATOR],
Expand Down Expand Up @@ -3064,6 +3048,14 @@ static struct amount_sat check_balances(struct peer *peer,
max_initiator_fee = amount_tx_fee(peer->feerate_max,
calc_weight(TX_INITIATOR, psbt));

/* Sometimes feerate_max is some absurdly high value, in that case we
* give a fee warning based of a multiple of the min value. */
amount_sat_mul(&min_multiplied, min_accepter_fee, 5);
max_accepter_fee = SAT_MIN(min_multiplied, max_accepter_fee);

amount_sat_mul(&min_multiplied, min_initiator_fee, 5);
max_initiator_fee = SAT_MIN(min_multiplied, max_initiator_fee);

/* Check initiator fee */
if (amount_msat_less_sat(initiator_fee, min_initiator_fee)) {
msg = towire_channeld_splice_feerate_error(NULL, initiator_fee,
Expand Down Expand Up @@ -3302,11 +3294,11 @@ static void resume_splice_negotiation(struct peer *peer,
txsig_tlvs);

if (do_i_sign_first(peer, current_psbt, our_role)) {
status_debug("Splice: we sign first");
msg = towire_channeld_update_inflight(NULL, current_psbt,
NULL, NULL);
wire_sync_write(MASTER_FD, take(msg));
peer_write(peer->pps, sigmsg);
status_debug("Splice: we signed first");
}

msg = peer_read(tmpctx, peer->pps);
Expand Down Expand Up @@ -3423,8 +3415,8 @@ static void resume_splice_negotiation(struct peer *peer,
wire_sync_write(MASTER_FD, take(msg));

if (!do_i_sign_first(peer, current_psbt, our_role)) {
status_debug("Splice: we sign second");
peer_write(peer->pps, sigmsg);
status_debug("Splice: we signed second");
}

peer->splicing = tal_free(peer->splicing);
Expand Down Expand Up @@ -4263,12 +4255,8 @@ static int cmp_changed_htlc_id(const struct changed_htlc *a,
static void resend_commitment(struct peer *peer, struct changed_htlc *last)
{
size_t i;
struct bitcoin_signature commit_sig, *htlc_sigs;
u8 *msg;
struct bitcoin_tx **txs;
const u8 *funding_wscript;
const struct htlc **htlc_map;
struct wally_tx_output *direct_outputs[NUM_SIDES];
u8 **msgs = tal_arr(tmpctx, u8*, 1);

status_debug("Retransmitting commitment, feerate LOCAL=%u REMOTE=%u,"
" blockheight LOCAL=%u REMOTE=%u",
Expand Down Expand Up @@ -4359,19 +4347,37 @@ static void resend_commitment(struct peer *peer, struct changed_htlc *last)
}
}

/* Re-send the commitment_signed itself. */
txs = channel_txs(tmpctx, &htlc_map, direct_outputs,
&funding_wscript, peer->channel, &peer->remote_per_commit,
peer->next_index[REMOTE]-1, REMOTE);
msgs[0] = send_commit_part(peer, &peer->channel->funding,
peer->channel->funding_sats, NULL,
false, 0, 0, peer->next_index[REMOTE] - 1);

htlc_sigs = calc_commitsigs(tmpctx, peer, txs, funding_wscript, htlc_map, peer->next_index[REMOTE]-1,
&commit_sig);
/* Loop over current inflights
* BOLT-0d8b701614b09c6ee4172b04da2203e73deec7e2 #2:
*
* A sending node:
*...
* - MUST first send a `commitment_signed` for the active channel then immediately
* send a `commitment_signed` for each splice awaiting confirmation, in increasing
* feerate order.
*/
for (i = 0; i < tal_count(peer->splice_state->inflights); i++) {
s64 funding_diff = sats_diff(peer->splice_state->inflights[i]->amnt,
peer->channel->funding_sats);
s64 remote_splice_amnt = funding_diff
- peer->splice_state->inflights[i]->splice_amnt;

msg = towire_commitment_signed(NULL, &peer->channel_id,
&commit_sig.s,
raw_sigs(tmpctx, htlc_sigs),
NULL);
peer_write(peer->pps, take(msg));
tal_arr_expand(&msgs,
send_commit_part(peer,
&peer->splice_state->inflights[i]->outpoint,
peer->splice_state->inflights[i]->amnt,
NULL, false,
peer->splice_state->inflights[i]->splice_amnt,
remote_splice_amnt,
peer->next_index[REMOTE] - 1));
}

for(i = 0; i < tal_count(msgs); i++)
peer_write(peer->pps, take(msgs[i]));

/* If we have already received the revocation for the previous, the
* other side shouldn't be asking for a retransmit! */
Expand Down Expand Up @@ -4638,8 +4644,14 @@ static void peer_reconnect(struct peer *peer,
send_tlvs = tlv_channel_reestablish_tlvs_new(peer);

/* If inflight with no sigs on it, send next_funding */
if (inflight && !inflight->last_tx)
if (inflight && !inflight->last_tx) {
status_debug("Reestablish with an inflight but missing"
" last_tx, will send next_funding %s",
type_to_string(tmpctx,
struct bitcoin_txid,
&inflight->outpoint.txid));
send_tlvs->next_funding = &inflight->outpoint.txid;
}

/* BOLT-upgrade_protocol #2:
* A node sending `channel_reestablish`, if it supports upgrading channels:
Expand Down Expand Up @@ -4772,9 +4784,12 @@ static void peer_reconnect(struct peer *peer,
tal_hex(msg, msg));
}

status_debug("Got reestablish commit=%"PRIu64" revoke=%"PRIu64,
status_debug("Got reestablish commit=%"PRIu64" revoke=%"PRIu64
" inflights: %lu, active splices: %"PRIu32,
next_commitment_number,
next_revocation_number);
next_revocation_number,
tal_count(peer->splice_state->inflights),
peer->splice_state->count);

/* BOLT #2:
*
Expand Down Expand Up @@ -5079,6 +5094,7 @@ static void peer_reconnect(struct peer *peer,
&peer->channel->funding.txid));
}
else {
status_info("Resuming splice negotation");
resume_splice_negotiation(peer, inflight, false,
inflight->i_am_initiator
? TX_INITIATOR
Expand Down
18 changes: 14 additions & 4 deletions channeld/inflight.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,8 +12,15 @@ struct inflight *fromwire_inflight(const tal_t *ctx, const u8 **cursor, size_t *
inflight->amnt = fromwire_amount_sat(cursor, max);
inflight->psbt = fromwire_wally_psbt(inflight, cursor, max);
inflight->splice_amnt = fromwire_s64(cursor, max);
inflight->last_tx = fromwire_bitcoin_tx(inflight, cursor, max);
fromwire_bitcoin_signature(cursor, max, &inflight->last_sig);
int has_tx = fromwire_u8(cursor, max);
if(has_tx) {
inflight->last_tx = fromwire_bitcoin_tx(inflight, cursor, max);
fromwire_bitcoin_signature(cursor, max, &inflight->last_sig);
}
else {
inflight->last_tx = NULL;
memset(&inflight->last_sig, 0, sizeof(inflight->last_sig));
}
inflight->i_am_initiator = fromwire_bool(cursor, max);

return inflight;
Expand All @@ -25,8 +32,11 @@ void towire_inflight(u8 **pptr, const struct inflight *inflight)
towire_amount_sat(pptr, inflight->amnt);
towire_wally_psbt(pptr, inflight->psbt);
towire_s64(pptr, inflight->splice_amnt);
towire_bitcoin_tx(pptr, inflight->last_tx);
towire_bitcoin_signature(pptr, &inflight->last_sig);
towire_u8(pptr, inflight->last_tx ? 1 : 0);
if(inflight->last_tx) {
towire_bitcoin_tx(pptr, inflight->last_tx);
towire_bitcoin_signature(pptr, &inflight->last_sig);
}
towire_bool(pptr, inflight->i_am_initiator);
}

Expand Down
4 changes: 4 additions & 0 deletions common/jsonrpc_errors.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -73,6 +73,10 @@ enum jsonrpc_errcode {
SPLICE_NOT_SUPPORTED = 354,
SPLICE_BUSY_ERROR = 355,
SPLICE_INPUT_ERROR = 356,
SPLICE_FUNDING_LOW = 357,
SPLICE_STATE_ERROR = 358,
SPLICE_LOW_FEE = 359,
SPLICE_HIGH_FEE = 360,

/* `connect` errors */
CONNECT_NO_KNOWN_ADDRESS = 400,
Expand Down
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