splice: Add details to log message
What the developer wrote
Authored by Dusty Daemon
splice: Add details to log message
Make the failure reason more clear by adding more information to the signature failure message.
What changed, and why it matters
This change only improves an error message shown when a splicing (channel funding update) negotiation fails because the remote peer did not send enough signatures. It adds a count of how many remote inputs need signatures and how many signature bundles were actually received. There is no code behavior change that fixes or introduces a vulnerability; it is purely a diagnostic/logging improvement.
No security action required. Treat as a normal logging/diagnostics improvement during review or deployment.
Security signals we found
No security fix or behavior change present in diff
Change is limited to error-message string formatting and a counting loop
Existing failure path (peer_failed_warn) is preserved; only diagnostics added
Evidence from the diff
The commit modifies resume_splice_negotiation() in channeld/channeld.c. It introduces a new local counter, remote_inputs_needing_sigs, computed by iterating over PSBT inputs and skipping inputs owned by the local role and the splice funding input. When the witness bundle index j reaches tal_count(inws) before all required remote inputs are satisfied, the existing peer_failed_warn() call is updated to include remote_inputs_needing_sigs and tal_count(inws) in the message. No signature validation, authorization, or state-machine logic is altered.
Changed components
channeld/channeld.cresume_splice_negotiation()splicing error reportingInspect captured patch +31 / −2
diff --git a/channeld/channeld.c b/channeld/channeld.c
index 21bfcd2..f00b2b1 100644
--- a/channeld/channeld.c
+++ b/channeld/channeld.c
@@ -3512,6 +3512,7 @@ static void resume_splice_negotiation(struct peer *peer,
const u8 *msg_received;
struct witness **inws;
struct bitcoin_signature *their_sig;
+ size_t remote_inputs_needing_sigs;
if (peer->splicing) {
inws = peer->splicing->inws;
@@ -3755,6 +3756,28 @@ static void resume_splice_negotiation(struct peer *peer,
" received",
tal_count(inws) - current_psbt->num_inputs);
+ remote_inputs_needing_sigs = 0;
+ for (size_t i = 0; i < current_psbt->num_inputs; i++) {
+ struct wally_psbt_input *in =
+ ¤t_psbt->inputs[i];
+ u64 in_serial;
+
+ if (!psbt_get_serial_id(&in->unknowns, &in_serial)) {
+ status_broken("PSBT input %zu missing serial_id"
+ " %s", i,
+ fmt_wally_psbt(tmpctx,
+ current_psbt));
+ return;
+ }
+ if (in_serial % 2 == our_role)
+ continue;
+
+ if (i == splice_funding_index)
+ continue;
+
+ remote_inputs_needing_sigs++;
+ }
+
/* We put the PSBT + sigs all together */
for (size_t j = 0, i = 0; i < current_psbt->num_inputs; i++) {
struct wally_psbt_input *in =
@@ -3774,12 +3797,18 @@ static void resume_splice_negotiation(struct peer *peer,
if (i == splice_funding_index)
continue;
- if (j == tal_count(inws))
+ if (j == tal_count(inws)) {
peer_failed_warn(peer->pps,
&peer->channel_id,
"Mismatch witness stack count."
" Most likely you are missing"
- " signatures.");
+ " signatures. We have %zu"
+ " remote inputs needing sigs"
+ " and you sent %zu witness"
+ " bundles.",
+ remote_inputs_needing_sigs,
+ tal_count(inws));
+ }
psbt_finalize_input(current_psbt, in,
inws[j++]);
Why this scored 16/100
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