openingd: allow funding_failed to complete successfully

For the `fundchannel_cancel` we're going to want
to 'successfully' fail a funding channel operation. This allows
us to report it a failure back as an RPC success, instead of
automatically failing the RPC request.

lightningd/opening_control.c

@@ -573,8 +573,11 @@ static void opening_funder_failed(struct subd *openingd, const u8 *msg,
 				  struct uncommitted_channel *uc)
 {
 	char *desc;
+	bool is_err;
 
-	if (!fromwire_opening_funder_failed(msg, msg, &desc)) {
+	struct json_stream *response;
+
+	if (!fromwire_opening_funder_failed(msg, msg, &desc, &is_err)) {
 		log_broken(uc->log,
 			   "bad OPENING_FUNDER_FAILED %s",
 			   tal_hex(tmpctx, msg));
@@ -585,7 +588,15 @@ static void opening_funder_failed(struct subd *openingd, const u8 *msg,
 		return;
 	}
 
-	was_pending(command_fail(uc->fc->cmd, LIGHTNINGD, "%s", desc));
+	if (is_err)
+		was_pending(command_fail(uc->fc->cmd, LIGHTNINGD, "%s", desc));
+	else {
+		response = json_stream_success(uc->fc->cmd);
+		json_stream_append(response, "\"");
+		json_stream_append(response, desc);
+		json_stream_append(response, "\"");
+		was_pending(command_success(uc->fc->cmd, response));
+	}
 
 	/* Clear uc->fc, so we can try again, and so we don't fail twice
 	 * if they close. */

openingd/opening_wire.csv

@@ -80,6 +80,7 @@ opening_funder_reply,,shutdown_scriptpubkey,shutdown_len*u8
 # Openingd->master: we failed to negotiation channel
 opening_funder_failed,6004
 opening_funder_failed,,reason,wirestring
+opening_funder_failed,,is_err,bool
 
 # Openingd->master: they offered channel.
 # This gives their txid and info, means we can send funding_signed: we're done.

openingd/openingd.c

@@ -116,7 +116,7 @@ static const u8 *dev_upfront_shutdown_script(const tal_t *ctx)
 /*~ If we can't agree on parameters, we fail to open the channel.  If we're
  * the funder, we need to tell lightningd, otherwise it never really notices. */
 static void negotiation_aborted(struct state *state, bool am_funder,
-				const char *why)
+				const char *why, bool is_err)
 {
 	status_debug("aborted opening negotiation: %s", why);
 	/*~ The "billboard" (exposed as "status" in the JSON listpeers RPC
@@ -129,7 +129,7 @@ static void negotiation_aborted(struct state *state, bool am_funder,
 
 	/* If necessary, tell master that funding failed. */
 	if (am_funder) {
-		u8 *msg = towire_opening_funder_failed(NULL, why);
+		u8 *msg = towire_opening_funder_failed(NULL, why, is_err);
 		wire_sync_write(REQ_FD, take(msg));
 	}
 
@@ -155,7 +155,7 @@ static void negotiation_failed(struct state *state, bool am_funder,
 			      "You gave bad parameters: %s", errmsg);
 	sync_crypto_write(state->pps, take(msg));
 
-	negotiation_aborted(state, am_funder, errmsg);
+	negotiation_aborted(state, am_funder, errmsg, true);
 }
 
 /*~ This is the key function that checks that their configuration is reasonable:
@@ -399,7 +399,8 @@ static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state,
 			if (all_channels) {
 				if (am_funder) {
 					msg = towire_opening_funder_failed(NULL,
-									   err);
+									   err,
+									   true);
 					wire_sync_write(REQ_FD, take(msg));
 				}
 				peer_failed_received_errmsg(state->pps, err,
@@ -407,7 +408,8 @@ static u8 *opening_negotiate_msg(const tal_t *ctx, struct state *state,
 			}
 			negotiation_aborted(state, am_funder,
 					    tal_fmt(tmpctx, "They sent error %s",
-						    err));
+						    err),
+					    true);
 			/* Return NULL so caller knows to stop negotiating. */
 			return NULL;
 		}