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Splice Interop #8817

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9809f92
splice: Fix log message
ddustin Jan 5, 2026
9f850c3
splice: Handle CHANNEL_READY during splice resume
ddustin Jan 7, 2026
1e14668
splice: RPC error handling fix
ddustin Jan 8, 2026
8e56bc7
reestablish: Send announcement sigs when asked
ddustin Jan 5, 2026
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80 changes: 63 additions & 17 deletions channeld/channeld.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3004,11 +3004,12 @@ static struct wally_psbt *next_splice_step(const tal_t *ctx,
return ictx->desired_psbt;
}

static const u8 *peer_expect_msg_three(const tal_t *ctx,
static const u8 *peer_expect_msg_four(const tal_t *ctx,
struct peer *peer,
enum peer_wire expect_type,
enum peer_wire second_allowed_type,
enum peer_wire third_allowed_type)
enum peer_wire third_allowed_type,
enum peer_wire fourth_allowed_type)
{
u8 *msg;
enum peer_wire type;
Expand All @@ -3019,14 +3020,22 @@ static const u8 *peer_expect_msg_three(const tal_t *ctx,
&& type != third_allowed_type)
peer_failed_warn(peer->pps, &peer->channel_id,
"Got incorrect message from peer: %s"
" (should be %s) [%s]",
" (should be %s or %s or %s of %s) [%s]",
peer_wire_name(type),
peer_wire_name(expect_type),
peer_wire_name(second_allowed_type),
peer_wire_name(third_allowed_type),
peer_wire_name(fourth_allowed_type),
sanitize_error(tmpctx, msg, &peer->channel_id));

return msg;
}

/* In some circumstances Eclair send CHANNEL_READY after CHANNEL_REESTABLISH but
* before resuming splice negotiation, so we need a way to process it in this
* order. */
static void peer_in(struct peer *peer, const u8 *msg);

/* The question of "who signs splice commitments first" is the same order as the
* splice `tx_signature`s are. This function handles sending & receiving the
* required commitments as part of the splicing process.
Expand All @@ -3038,7 +3047,8 @@ static struct commitsig *interactive_send_commitments(struct peer *peer,
size_t inflight_index,
bool send_commitments,
bool recv_commitments,
const u8 **msg_received)
const u8 **msg_received,
int allowed_premature_msg)
{
struct commitsig_info *result;
const u8 *msg;
Expand Down Expand Up @@ -3080,10 +3090,21 @@ static struct commitsig *interactive_send_commitments(struct peer *peer,
result = NULL;

if (recv_commitments) {
msg = peer_expect_msg_three(tmpctx, peer,
WIRE_COMMITMENT_SIGNED,
WIRE_TX_SIGNATURES,
WIRE_TX_ABORT);
msg = peer_expect_msg_four(tmpctx, peer,
WIRE_COMMITMENT_SIGNED,
WIRE_TX_SIGNATURES,
WIRE_TX_ABORT,
allowed_premature_msg);

if (allowed_premature_msg
&& fromwire_peektype(msg) == allowed_premature_msg) {
peer_in(peer, msg);
msg = peer_expect_msg_four(tmpctx, peer,
WIRE_COMMITMENT_SIGNED,
WIRE_TX_SIGNATURES,
WIRE_TX_ABORT,
0);
}

check_tx_abort(peer, msg, &inflight->outpoint.txid);

Expand Down Expand Up @@ -3633,7 +3654,8 @@ static void resume_splice_negotiation(struct peer *peer,
bool send_commitments,
bool recv_commitments,
bool send_signature,
bool recv_signature)
bool recv_signature,
int allowed_premature_msg)
{
struct inflight *inflight = last_inflight(peer);
enum tx_role our_role = inflight->i_am_initiator
Expand Down Expand Up @@ -3692,7 +3714,8 @@ static void resume_splice_negotiation(struct peer *peer,
last_inflight_index(peer),
send_commitments,
recv_commitments,
&msg_received);
&msg_received,
allowed_premature_msg);

check_tx_abort(peer, msg_received, &inflight->outpoint.txid);

Expand Down Expand Up @@ -4250,7 +4273,7 @@ static void splice_accepter(struct peer *peer, const u8 *inmsg)

peer->splice_state->count++;

resume_splice_negotiation(peer, true, true, true, true);
resume_splice_negotiation(peer, true, true, true, true, 0);
}

/* splice_initiator runs when splice_ack is received by the other side. It
Expand Down Expand Up @@ -4556,7 +4579,7 @@ static void splice_initiator_user_finalized(struct peer *peer)
their_commit = interactive_send_commitments(peer, new_inflight->psbt,
our_role,
last_inflight_index(peer),
true, true, NULL);
true, true, NULL, 0);

new_inflight->last_tx = tal_steal(new_inflight, their_commit->tx);
new_inflight->last_sig = their_commit->commit_signature;
Expand All @@ -4572,7 +4595,7 @@ static void splice_initiator_user_finalized(struct peer *peer)
peer->splicing->force_sign_first);

if (!sign_first)
resume_splice_negotiation(peer, false, false, false, true);
resume_splice_negotiation(peer, false, false, false, true, 0);

outmsg = towire_channeld_splice_confirmed_update(NULL,
new_inflight->psbt,
Expand Down Expand Up @@ -4773,7 +4796,7 @@ static void splice_initiator_user_signed(struct peer *peer, const u8 *inmsg)
audit_psbt(inflight->psbt, inflight->psbt);
assert(tal_parent(inflight->psbt) != tmpctx);

resume_splice_negotiation(peer, false, false, true, sign_first);
resume_splice_negotiation(peer, false, false, true, sign_first, 0);

audit_psbt(inflight->psbt, inflight->psbt);
assert(tal_parent(inflight->psbt) != tmpctx);
Expand Down Expand Up @@ -5499,6 +5522,7 @@ static void peer_reconnect(struct peer *peer,
const struct secret *last_remote_per_commit_secret)
{
struct channel_id channel_id;
bool announcement_sigs_requested;
/* Note: BOLT #2 uses these names! */
u64 next_commitment_number, next_revocation_number;
bool retransmit_revoke_and_ack, retransmit_commitment_signed;
Expand Down Expand Up @@ -5705,6 +5729,8 @@ static void peer_reconnect(struct peer *peer,
do {
clean_tmpctx();
msg = peer_read(tmpctx, peer->pps);
check_tx_abort(peer, msg,
inflight ? &inflight->outpoint.txid : NULL);
} while (handle_peer_error_or_warning(peer->pps, msg) ||
capture_premature_msg(&premature_msgs, msg));

Expand Down Expand Up @@ -5757,7 +5783,8 @@ static void peer_reconnect(struct peer *peer,
false,
!inflight->last_tx,
false,
true);
true,
WIRE_CHANNEL_READY);
} else if (bitcoin_txid_eq(&remote_next_funding->next_funding_txid,
&inflight->outpoint.txid)) {
/* Don't send sigs unless we have theirs */
Expand All @@ -5773,7 +5800,8 @@ static void peer_reconnect(struct peer *peer,
: false,
local_next_funding && !inflight->last_tx,
true,
local_next_funding);
local_next_funding,
WIRE_CHANNEL_READY);
} else if (bitcoin_txid_eq(&remote_next_funding->next_funding_txid,
&peer->channel->funding.txid)) {
peer_failed_err(peer->pps,
Expand Down Expand Up @@ -5989,6 +6017,24 @@ static void peer_reconnect(struct peer *peer,
if (retransmit_revoke_and_ack && peer->last_was_revoke)
resend_revoke(peer);

/* BOLT-??? #2
* 1. type: 5 (`my_current_funding_locked`)
* 2. data:
* * [`sha256`:`my_current_funding_locked_txid`]
* * [`byte`:`retransmit_flags`]
*
* The `retransmit_flags` bitfield is used to let our peer know which messages
* we expect them to retransmit after the reconnection:
*
* | Bit Position | Name |
* | ------------- | --------------------------|
* | 0 | `announcement_signatures` |
*/
announcement_sigs_requested = false;
if (recv_tlvs && recv_tlvs->my_current_funding_locked
&& recv_tlvs->my_current_funding_locked->retransmit_flags & 1)
announcement_sigs_requested = true;

/* BOLT #2:
*
* - upon reconnection:
Expand All @@ -6001,7 +6047,7 @@ static void peer_reconnect(struct peer *peer,
tal_free(send_tlvs);

/* We've reestablished! */
wire_sync_write(MASTER_FD, take(towire_channeld_reestablished(NULL)));
wire_sync_write(MASTER_FD, take(towire_channeld_reestablished(NULL, announcement_sigs_requested)));

/* Corner case: we didn't send shutdown before because update_add_htlc
* pending, but now they're cleared by restart, and we're actually
Expand Down
1 change: 1 addition & 0 deletions channeld/channeld_wire.csv
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,7 @@ msgdata,channeld_init,scid_alias,short_channel_id,

# channeld->lightningd: successfully negotated reestablishment.
msgtype,channeld_reestablished,1101
msgdata,channeld_reestablished,announcement_sigs_requested,bool,

# master->channeld funding hit new depth(funding locked if >= lock depth)
# short_channel_id != NULL once we have 3+ confirmations
Expand Down
59 changes: 38 additions & 21 deletions lightningd/channel_control.c
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Original file line number Diff line number Diff line change
Expand Up @@ -482,7 +482,6 @@ static void handle_splice_lookup_tx(struct lightningd *ld,
/* Extra splice data we want to store for bitcoin send tx interface */
struct send_splice_info
{
struct splice_command *cc;
struct channel *channel;
const struct bitcoin_tx *final_tx;
u32 output_index;
Expand All @@ -497,6 +496,7 @@ static void handle_tx_broadcast(struct send_splice_info *info)
struct bitcoin_txid txid;
u8 *tx_bytes;
int num_utxos;
struct splice_command *cc;

tx_bytes = linearize_tx(tmpctx, info->final_tx);
bitcoin_txid(info->final_tx, &txid);
Expand All @@ -508,15 +508,17 @@ static void handle_tx_broadcast(struct send_splice_info *info)
if (num_utxos)
wallet_transaction_add(ld->wallet, info->final_tx->wtx, 0, 0);

if (info->cc) {
response = json_stream_success(info->cc->cmd);
cc = splice_command_for_chan(ld, info->channel);

if (cc) {
response = json_stream_success(cc->cmd);

json_add_hex(response, "tx", tx_bytes, tal_bytelen(tx_bytes));
json_add_txid(response, "txid", &txid);
json_add_u32(response, "outnum", info->output_index);
json_add_psbt(response, "psbt", info->psbt);

was_pending(command_success(info->cc->cmd, response));
was_pending(command_success(cc->cmd, response));
}
}

Expand All @@ -527,25 +529,32 @@ static void check_utxo_block(struct bitcoind *bitcoind UNUSED,
void *arg)
{
struct send_splice_info *info = arg;
struct lightningd *ld = info->channel->peer->ld;
struct splice_command *cc;

if(!txout) {
if (info->cc)
was_pending(command_fail(info->cc->cmd,
cc = splice_command_for_chan(ld, info->channel);
if (cc)
was_pending(command_fail(cc->cmd,
SPLICE_BROADCAST_FAIL,
"Error broadcasting splice "
"tx: %s. Unsent tx discarded "
"%s.",
"Error broadcasting splice"
" %s. Unsent tx discarded"
" %s.",
info->err_msg,
fmt_wally_tx(tmpctx,
info->final_tx->wtx)));
info->final_tx && info->final_tx->wtx ?
fmt_wally_tx(tmpctx,
info->final_tx->wtx)
: "NULL"));

log_unusual(info->channel->log,
"Error broadcasting splice "
"tx: %s. Unsent tx discarded "
"%s.",
"Error broadcasting splice"
" %s. Unsent tx discarded"
" %s.",
info->err_msg,
fmt_wally_tx(tmpctx,
info->final_tx->wtx));
info->final_tx && info->final_tx->wtx ?
fmt_wally_tx(tmpctx,
info->final_tx->wtx)
: "NULL");
}
else
handle_tx_broadcast(info);
Expand All @@ -558,8 +567,6 @@ static void send_splice_tx_done(struct bitcoind *bitcoind UNUSED,
bool success, const char *msg,
struct send_splice_info *info)
{
/* A NULL value of `info->cc` means we got here without user intiation.
* This means we are the ACCEPTER side of the splice */
struct lightningd *ld = info->channel->peer->ld;
struct bitcoin_outpoint outpoint;

Expand Down Expand Up @@ -593,7 +600,6 @@ static void send_splice_tx(struct channel *channel,

struct send_splice_info *info = tal(NULL, struct send_splice_info);

info->cc = tal_steal(info, cc);
info->channel = channel;
info->final_tx = tal_steal(info, tx);
info->output_index = output_index;
Expand Down Expand Up @@ -1305,6 +1311,17 @@ static void peer_got_shutdown(struct channel *channel, const u8 *msg)
wallet_channel_save(ld->wallet, channel);
}

static void peer_channeld_reestablished(struct channel *channel, const u8* msg)
{
bool announcement_sigs_requested;
if (!fromwire_channeld_reestablished(tmpctx, &announcement_sigs_requested))
channel_internal_error(channel,
"bad channeld_reestablished %s",
tal_hex(channel, msg));

channel_gossip_channel_reestablished(channel, announcement_sigs_requested);
}

void channel_fallen_behind(struct channel *channel)
{
channel->has_future_per_commitment_point = true;
Expand Down Expand Up @@ -1559,7 +1576,7 @@ static unsigned channel_msg(struct subd *sd, const u8 *msg, const int *fds)
peer_got_shutdown(sd->channel, msg);
break;
case WIRE_CHANNELD_REESTABLISHED:
channel_gossip_channel_reestablished(sd->channel);
peer_channeld_reestablished(sd->channel, msg);
break;
case WIRE_CHANNELD_SHUTDOWN_COMPLETE:
/* We expect 1 fd. */
Expand Down Expand Up @@ -1917,7 +1934,7 @@ bool peer_start_channeld(struct channel *channel,

/* "Reestablished" if we've just opened. */
if (!reconnected)
channel_gossip_channel_reestablished(channel);
channel_gossip_channel_reestablished(channel, false);

/* FIXME: DTODO: Use a pointer to a txid instead of zero'ing one out. */
memset(&txid, 0, sizeof(txid));
Expand Down
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