From 4b3643d2090e10e4a9bc29dea0c9d69e86a8dd9f Mon Sep 17 00:00:00 2001
From: Dusty Daemon <dustinpaystaxes@gmail.com>
Date: Fri, 4 Oct 2024 15:14:21 -0400
Subject: [PATCH] splice: Clean up error messages for RPC

Added and updated error messages when splicing to make it more clear to the user why a splice is failing.

Changelog-Changed: Improved error messaging for splice commands.
---
 channeld/channeld.c          | 22 +++++++++++++++++-----
 common/jsonrpc_errors.h      |  1 +
 lightningd/channel_control.c | 27 ++++++++++++++++++++++++---
 3 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/channeld/channeld.c b/channeld/channeld.c
index 503f6fb60..923450044 100644
--- a/channeld/channeld.c
+++ b/channeld/channeld.c
@@ -235,14 +235,15 @@ static void end_stfu_mode(struct peer *peer)
 	status_debug("Left STFU mode.");
 }
 
-static void maybe_send_stfu(struct peer *peer)
+static bool maybe_send_stfu(struct peer *peer)
 {
 	if (!peer->want_stfu)
-		return;
+		return false;
 
 	if (pending_updates(peer->channel, LOCAL, false)) {
 		status_info("Pending updates prevent us from STFU mode at this"
 			    " time.");
+		return false;
 	}
 	else if (!peer->stfu_sent[LOCAL]) {
 		status_debug("Sending peer that we want to STFU.");
@@ -269,6 +270,8 @@ static void maybe_send_stfu(struct peer *peer)
 			peer->on_stfu_success = NULL;
 		}
 	}
+
+	return true;
 }
 
 /* Durring reestablish, STFU mode is assumed if continuing a splice */
@@ -1666,7 +1669,7 @@ static bool have_they_signed_inflight(const struct peer *peer,
 	return has_sig;
 }
 
-/* this checks if local has signed everything buy the funding input */
+/* This checks if local has signed everything but the funding input */
 static bool missing_user_signatures(const struct peer *peer,
 				    const struct inflight *inflight)
 {
@@ -3387,7 +3390,7 @@ static void resume_splice_negotiation(struct peer *peer,
 					    		&inws),
 					    &their_txsigs_tlvs))
 			peer_failed_warn(peer->pps, &peer->channel_id,
-				    "Splicing bad tx_signatures %s",
+				    "Splicing bad tx_signatures msg %s",
 				    tal_hex(msg, msg));
 
 		if (peer->splicing)
@@ -4296,7 +4299,16 @@ static void handle_stfu_req(struct peer *peer, const u8 *inmsg)
 
 	peer->stfu_initiator = LOCAL;
 	peer->want_stfu = true;
-	maybe_send_stfu(peer);
+
+	if (!maybe_send_stfu(peer)) {
+		msg = towire_channeld_splice_state_error(NULL, tal_fmt(tmpctx,
+							 "Pending updates"
+							 " prevent us from STFU"
+							 " mode at this"
+							 " time."));
+		wire_sync_write(MASTER_FD, take(msg));
+		return;
+	}
 }
 
 static void handle_abort_req(struct peer *peer, const u8 *inmsg)
diff --git a/common/jsonrpc_errors.h b/common/jsonrpc_errors.h
index 000ae8b3a..da9e33772 100644
--- a/common/jsonrpc_errors.h
+++ b/common/jsonrpc_errors.h
@@ -84,6 +84,7 @@ enum jsonrpc_errcode {
 	SPLICE_LOW_FEE = 359,
 	SPLICE_HIGH_FEE = 360,
 	SPLICE_ABORT = 362,
+	SPLICE_CHANNEL_ERROR = 363,
 
 	/* `connect` errors */
 	CONNECT_NO_KNOWN_ADDRESS = 400,
diff --git a/lightningd/channel_control.c b/lightningd/channel_control.c
index e545714a0..21a923d86 100644
--- a/lightningd/channel_control.c
+++ b/lightningd/channel_control.c
@@ -1625,6 +1625,27 @@ static unsigned channel_msg(struct subd *sd, const u8 *msg, const int *fds)
 	return 0;
 }
 
+/* If we get a disconnecting warning or error during a splice command, let
+ * the user know out of an abundance of politeness.
+ * After, we forward the event onto the standard `channel_errmsg`. */
+static void channel_control_errmsg(struct channel *channel,
+				   struct peer_fd *peer_fd,
+				   const char *desc,
+				   const u8 *err_for_them,
+				   bool disconnect,
+				   bool warning)
+{
+	struct lightningd *ld = channel->peer->ld;
+	struct splice_command *cc = splice_command_for_chan(ld, channel);
+	if (cc && disconnect) {
+		was_pending(command_fail(cc->cmd, SPLICE_CHANNEL_ERROR,
+					 "Splice command failed:"
+					 " %s", desc));
+	}
+
+	channel_errmsg(channel, peer_fd, desc, err_for_them, disconnect, warning);
+}
+
 bool peer_start_channeld(struct channel *channel,
 			 struct peer_fd *peer_fd,
 			 const u8 *fwd_msg,
@@ -1674,7 +1695,7 @@ bool peer_start_channeld(struct channel *channel,
 					   channel->log, true,
 					   channeld_wire_name,
 					   channel_msg,
-					   channel_errmsg,
+					   channel_control_errmsg,
 					   channel_set_billboard,
 					   take(&peer_fd->fd),
 					   take(&hsmfd), NULL));
@@ -2139,9 +2160,9 @@ static struct command_result *channel_for_splice(struct command *cmd,
 
 	if (!feature_negotiated(cmd->ld->our_features,
 			        (*channel)->peer->their_features,
-				OPT_EXPERIMENTAL_SPLICE))
+				OPT_SPLICE))
 		return command_fail(cmd, SPLICE_NOT_SUPPORTED,
-				    "splicing not supported");
+				    "Peer does not support splicing");
 
 	if (!(*channel)->owner)
 		return command_fail(cmd, SPLICE_WRONG_OWNER,