json-rpc: make commands return 'struct command_result *'.

Usually, this means they return 'command_param_failed()' if param()
fails, and changing 'command_success(); return;' to 'return
command_success()'.

Occasionally, it's more complex: there's a command_its_complicated()
for the case where we can't exactly determine what the status is,
but it should be considered a last resort.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/chaintopology.c

@@ -463,7 +463,7 @@ u32 feerate_to_style(u32 feerate_perkw, enum feerate_style style)
 	abort();
 }
 
-static void json_feerates(struct command *cmd,
+static struct command_result *json_feerates(struct command *cmd,
 					    const char *buffer,
 					    const jsmntok_t *obj UNNEEDED,
 					    const jsmntok_t *params)
@@ -477,7 +477,7 @@ static void json_feerates(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_req("style", param_feerate_style, &style),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	missing = false;
 	for (size_t i = 0; i < ARRAY_SIZE(feerates); i++) {
@@ -520,7 +520,7 @@ static void json_feerates(struct command *cmd,
 
 	json_object_end(response);
 
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command feerates_command = {

lightningd/connect_control.c

@@ -65,16 +65,17 @@ static struct connect *find_connect(struct lightningd *ld,
 	return NULL;
 }
 
-static void connect_cmd_succeed(struct command *cmd, const struct pubkey *id)
+static struct command_result *connect_cmd_succeed(struct command *cmd,
+						  const struct pubkey *id)
 {
 	struct json_stream *response = json_stream_success(cmd);
 	json_object_start(response, NULL);
 	json_add_pubkey(response, "id", id);
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
-static void json_connect(struct command *cmd,
+static struct command_result *json_connect(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNNEEDED,
 					   const jsmntok_t *params)
@@ -96,7 +97,7 @@ static void json_connect(struct command *cmd,
 		   p_opt("host", param_string, &name),
 		   p_opt("port", param_number, &port),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	/* Check for id@addrport form */
 	id_str = json_strdup(cmd, buffer, idtok);
@@ -109,18 +110,16 @@ static void json_connect(struct command *cmd,
 	}
 
 	if (!json_to_pubkey(buffer, idtok, &id)) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "id %.*s not valid",
 				    json_tok_full_len(idtok),
 				    json_tok_full(buffer, idtok));
-		return;
 	}
 
 	if (name && ataddr) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "Can't specify host as both xxx@yyy "
 				    "and separate argument");
-		return;
 	}
 
 	/* Get parseable host if provided somehow */
@@ -129,9 +128,8 @@ static void json_connect(struct command *cmd,
 
 	/* Port without host name? */
 	if (port && !name) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "Can't specify port without host");
-		return;
 	}
 
 	/* If we know about peer, see if it's already connected. */
@@ -141,8 +139,7 @@ static void json_connect(struct command *cmd,
 
 		if (peer->uncommitted_channel
 		    || (channel && channel->connected)) {
-			connect_cmd_succeed(cmd, &id);
-			return;
+			return connect_cmd_succeed(cmd, &id);
 		}
 	}
 
@@ -159,9 +156,10 @@ static void json_connect(struct command *cmd,
 					     && !cmd->ld->pure_tor_setup,
 					     true,
 					     &err_msg)) {
-			command_fail(cmd, LIGHTNINGD, "Host %s:%u not valid: %s",
-				     name, *port, err_msg ? err_msg : "port is 0");
-			return;
+			return command_fail(cmd, LIGHTNINGD,
+					    "Host %s:%u not valid: %s",
+					    name, *port,
+					    err_msg ? err_msg : "port is 0");
 		}
 	} else
 		addr = NULL;
@@ -171,7 +169,7 @@ static void json_connect(struct command *cmd,
 
 	/* Leave this here for peer_connected or connect_failed. */
 	new_connect(cmd->ld, &id, cmd);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command connect_command = {

lightningd/gossip_control.c

@@ -244,7 +244,7 @@ static void json_getnodes_reply(struct subd *gossip UNUSED, const u8 *reply,
 	command_success(cmd, response);
 }
 
-static void json_listnodes(struct command *cmd,
+static struct command_result *json_listnodes(struct command *cmd,
 					     const char *buffer,
 					     const jsmntok_t *obj UNNEEDED,
 					     const jsmntok_t *params)
@@ -255,11 +255,11 @@ static void json_listnodes(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt("id", param_pubkey, &id),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	req = towire_gossip_getnodes_request(cmd, id);
 	subd_req(cmd, cmd->ld->gossip, req, -1, 0, json_getnodes_reply, cmd);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command listnodes_command = {
@@ -289,7 +289,7 @@ static void json_getroute_reply(struct subd *gossip UNUSED, const u8 *reply, con
 	command_success(cmd, response);
 }
 
-static void json_getroute(struct command *cmd,
+static struct command_result *json_getroute(struct command *cmd,
 					    const char *buffer,
 					    const jsmntok_t *obj UNNEEDED,
 					    const jsmntok_t *params)
@@ -318,7 +318,7 @@ static void json_getroute(struct command *cmd,
 		   p_opt("seed", param_tok, &seedtok),
 		   p_opt_def("fuzzpercent", param_percent, &fuzz, 75.0),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	/* Convert from percentage */
 	*fuzz = *fuzz / 100.0;
@@ -338,7 +338,7 @@ static void json_getroute(struct command *cmd,
 						 *msatoshi, *riskfactor * 1000,
 						 *cltv, fuzz, &seed);
 	subd_req(ld->gossip, ld->gossip, req, -1, 0, json_getroute_reply, cmd);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command getroute_command = {
@@ -399,7 +399,7 @@ static void json_listchannels_reply(struct subd *gossip UNUSED, const u8 *reply,
 	command_success(cmd, response);
 }
 
-static void json_listchannels(struct command *cmd,
+static struct command_result *json_listchannels(struct command *cmd,
 						const char *buffer,
 						const jsmntok_t *obj UNNEEDED,
 						const jsmntok_t *params)
@@ -409,12 +409,12 @@ static void json_listchannels(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt("short_channel_id", param_short_channel_id, &id),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	req = towire_gossip_getchannels_request(cmd, id);
 	subd_req(cmd->ld->gossip, cmd->ld->gossip,
 		 req, -1, 0, json_listchannels_reply, cmd);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command listchannels_command = {
@@ -450,7 +450,7 @@ static void json_scids_reply(struct subd *gossip UNUSED, const u8 *reply,
 	command_success(cmd, response);
 }
 
-static void json_dev_query_scids(struct command *cmd,
+static struct command_result *json_dev_query_scids(struct command *cmd,
 						   const char *buffer,
 						   const jsmntok_t *obj UNNEEDED,
 						   const jsmntok_t *params)
@@ -466,17 +466,16 @@ static void json_dev_query_scids(struct command *cmd,
 		   p_req("id", param_pubkey, &id),
 		   p_req("scids", param_array, &scidstok),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	scids = tal_arr(cmd, struct short_channel_id, scidstok->size);
 	end = json_next(scidstok);
 	for (i = 0, t = scidstok + 1; t < end; t = json_next(t), i++) {
 		if (!json_to_short_channel_id(buffer, t, &scids[i])) {
-			command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 					    "scid %zu '%.*s' is not an scid",
 					    i, json_tok_full_len(t),
 					    json_tok_full(buffer, t));
-			return;
 		}
 	}
 
@@ -484,7 +483,7 @@ static void json_dev_query_scids(struct command *cmd,
 	msg = towire_gossip_query_scids(cmd, id, scids);
 	subd_req(cmd->ld->gossip, cmd->ld->gossip,
 		 take(msg), -1, 0, json_scids_reply, cmd);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command dev_query_scids_command = {
@@ -494,7 +493,8 @@ static const struct json_command dev_query_scids_command = {
 };
 AUTODATA(json_command, &dev_query_scids_command);
 
-static void json_dev_send_timestamp_filter(struct command *cmd,
+static struct command_result *
+json_dev_send_timestamp_filter(struct command *cmd,
 			       const char *buffer,
 			       const jsmntok_t *obj UNNEEDED,
 			       const jsmntok_t *params)
@@ -508,14 +508,14 @@ static void json_dev_send_timestamp_filter(struct command *cmd,
 		   p_req("first", param_number, &first),
 		   p_req("range", param_number, &range),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	log_debug(cmd->ld->log, "Setting timestamp range %u+%u", *first, *range);
 	/* Tell gossipd, since this is a gossip query. */
 	msg = towire_gossip_send_timestamp_filter(NULL, id, *first, *range);
 	subd_send_msg(cmd->ld->gossip, take(msg));
 
-	command_success(cmd, null_response(cmd));
+	return command_success(cmd, null_response(cmd));
 }
 
 static const struct json_command dev_send_timestamp_filter = {
@@ -564,7 +564,7 @@ static void json_channel_range_reply(struct subd *gossip UNUSED, const u8 *reply
 	command_success(cmd, response);
 }
 
-static void json_dev_query_channel_range(struct command *cmd,
+static struct command_result *json_dev_query_channel_range(struct command *cmd,
 					 const char *buffer,
 					 const jsmntok_t *obj UNNEEDED,
 					 const jsmntok_t *params)
@@ -578,13 +578,13 @@ static void json_dev_query_channel_range(struct command *cmd,
 		   p_req("first", param_number, &first),
 		   p_req("num", param_number, &num),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	/* Tell gossipd, since this is a gossip query. */
 	msg = towire_gossip_query_channel_range(cmd, id, *first, *num);
 	subd_req(cmd->ld->gossip, cmd->ld->gossip,
 		 take(msg), -1, 0, json_channel_range_reply, cmd);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command dev_query_channel_range_command = {
@@ -594,7 +594,8 @@ static const struct json_command dev_query_channel_range_command = {
 };
 AUTODATA(json_command, &dev_query_channel_range_command);
 
-static void json_dev_set_max_scids_encode_size(struct command *cmd,
+static struct command_result *
+json_dev_set_max_scids_encode_size(struct command *cmd,
 				   const char *buffer,
 				   const jsmntok_t *obj UNNEEDED,
 				   const jsmntok_t *params)
@@ -605,12 +606,12 @@ static void json_dev_set_max_scids_encode_size(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_req("max", param_number, &max),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	msg = towire_gossip_dev_set_max_scids_encode_size(NULL, *max);
 	subd_send_msg(cmd->ld->gossip, take(msg));
 
-	command_success(cmd, null_response(cmd));
+	return command_success(cmd, null_response(cmd));
 }
 
 static const struct json_command dev_set_max_scids_encode_size = {
@@ -620,17 +621,17 @@ static const struct json_command dev_set_max_scids_encode_size = {
 };
 AUTODATA(json_command, &dev_set_max_scids_encode_size);
 
-static void json_dev_suppress_gossip(struct command *cmd,
+static struct command_result *json_dev_suppress_gossip(struct command *cmd,
 						       const char *buffer,
 						       const jsmntok_t *obj UNNEEDED,
 						       const jsmntok_t *params)
 {
 	if (!param(cmd, buffer, params, NULL))
-		return;
+		return command_param_failed();
 
 	subd_send_msg(cmd->ld->gossip, take(towire_gossip_dev_suppress(NULL)));
 
-	command_success(cmd, null_response(cmd));
+	return command_success(cmd, null_response(cmd));
 }
 
 static const struct json_command dev_suppress_gossip = {

lightningd/invoice.c

@@ -62,7 +62,8 @@ static void json_add_invoice(struct json_stream *response,
 	json_object_end(response);
 }
 
-static void tell_waiter(struct command *cmd, const struct invoice *inv)
+static struct command_result *tell_waiter(struct command *cmd,
+					  const struct invoice *inv)
 {
 	struct json_stream *response;
 	const struct invoice_details *details;
@@ -71,13 +72,13 @@ static void tell_waiter(struct command *cmd, const struct invoice *inv)
 	if (details->state == PAID) {
 		response = json_stream_success(cmd);
 		json_add_invoice(response, details);
-		command_success(cmd, response);
+		return command_success(cmd, response);
 	} else {
 		/* FIXME: -2 should be a constant in jsonrpc_errors.h.  */
 		response = json_stream_fail(cmd, -2,
 					    "invoice expired during wait");
 		json_add_invoice(response, details);
-		command_failed(cmd, response);
+		return command_failed(cmd, response);
 	}
 }
 
@@ -111,8 +112,9 @@ static bool hsm_sign_b11(const u5 *u5bytes,
 	return true;
 }
 
-static bool parse_fallback(struct command *cmd,
-			   const char *buffer, const jsmntok_t *fallback,
+static struct command_result *parse_fallback(struct command *cmd,
+					     const char *buffer,
+					     const jsmntok_t *fallback,
 					     const u8 **fallback_script)
 
 {
@@ -124,15 +126,14 @@ static bool parse_fallback(struct command *cmd,
 						buffer, fallback,
 						fallback_script);
 	if (fallback_parse == ADDRESS_PARSE_UNRECOGNIZED) {
-		command_fail(cmd, LIGHTNINGD, "Fallback address not valid");
-		return false;
+		return command_fail(cmd, LIGHTNINGD,
+				    "Fallback address not valid");
 	} else if (fallback_parse == ADDRESS_PARSE_WRONG_NETWORK) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Fallback address does not match our network %s",
 				    get_chainparams(cmd->ld)->network_name);
-		return false;
 	}
-	return true;
+	return NULL;
 }
 
 /* BOLT11 struct wants an array of arrays (can provide multiple routes) */
@@ -291,7 +292,7 @@ static void gossipd_incoming_channels_reply(struct subd *gossipd,
 	command_success(info->cmd, response);
 }
 
-static void json_invoice(struct command *cmd,
+static struct command_result *json_invoice(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNNEEDED,
 					   const jsmntok_t *params)
@@ -316,23 +317,21 @@ static void json_invoice(struct command *cmd,
 		   p_opt("fallbacks", param_array, &fallbacks),
 		   p_opt("preimage", param_tok, &preimagetok),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	if (strlen(info->label->s) > INVOICE_MAX_LABEL_LEN) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "Label '%s' over %u bytes", info->label->s,
 				    INVOICE_MAX_LABEL_LEN);
-		return;
 	}
 
 	if (strlen(desc_val) >= BOLT11_FIELD_BYTE_LIMIT) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "Descriptions greater than %d bytes "
 				    "not yet supported "
 				    "(description length %zu)",
 				    BOLT11_FIELD_BYTE_LIMIT,
 				    strlen(desc_val));
-		return;
 	}
 
 	if (fallbacks) {
@@ -340,9 +339,11 @@ static void json_invoice(struct command *cmd,
 
 		fallback_scripts = tal_arr(cmd, const u8 *, 0);
 		for (i = fallbacks + 1; i < end; i = json_next(i)) {
-			if (!parse_fallback(cmd, buffer, i,
-					    tal_arr_expand(&fallback_scripts)))
-				return;
+			struct command_result *r;
+			r = parse_fallback(cmd, buffer, i,
+					   tal_arr_expand(&fallback_scripts));
+			if (r)
+				return r;
 		}
 	}
 
@@ -352,9 +353,8 @@ static void json_invoice(struct command *cmd,
 				preimagetok->end - preimagetok->start,
 				&info->payment_preimage,
 				sizeof(info->payment_preimage))) {
-			command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 					    "preimage must be 64 hex digits");
-			return;
 		}
 	} else
 		/* Generate random secret preimage. */
@@ -381,7 +381,7 @@ static void json_invoice(struct command *cmd,
 		 take(towire_gossip_get_incoming_channels(NULL)),
 		 -1, 0, gossipd_incoming_channels_reply, info);
 
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command invoice_command = {
@@ -416,7 +416,7 @@ static void json_add_invoices(struct json_stream *response,
 	}
 }
 
-static void json_listinvoices(struct command *cmd,
+static struct command_result *json_listinvoices(struct command *cmd,
 						const char *buffer,
 						const jsmntok_t *obj UNNEEDED,
 						const jsmntok_t *params)
@@ -427,14 +427,14 @@ static void json_listinvoices(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt("label", param_label, &label),
 		   NULL))
-		return;
+		return command_param_failed();
 	response = json_stream_success(cmd);
 	json_object_start(response, NULL);
 	json_array_start(response, "invoices");
 	json_add_invoices(response, wallet, label);
 	json_array_end(response);
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command listinvoices_command = {
@@ -444,7 +444,7 @@ static const struct json_command listinvoices_command = {
 };
 AUTODATA(json_command, &listinvoices_command);
 
-static void json_delinvoice(struct command *cmd,
+static struct command_result *json_delinvoice(struct command *cmd,
 					      const char *buffer,
 					      const jsmntok_t *obj UNNEEDED,
 					      const jsmntok_t *params)
@@ -460,11 +460,10 @@ static void json_delinvoice(struct command *cmd,
 		   p_req("label", param_label, &label),
 		   p_req("status", param_string, &status),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	if (!wallet_invoice_find_by_label(wallet, &i, label)) {
-		command_fail(cmd, LIGHTNINGD, "Unknown invoice");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Unknown invoice");
 	}
 
 	details = wallet_invoice_details(cmd, cmd->ld->wallet, i);
@@ -473,22 +472,21 @@ static void json_delinvoice(struct command *cmd,
 	 * might not make sense if it changed! */
 	actual_status = invoice_status_str(details);
 	if (!streq(actual_status, status)) {
-		command_fail(cmd, LIGHTNINGD, "Invoice status is %s not %s",
+		return command_fail(cmd, LIGHTNINGD,
+				    "Invoice status is %s not %s",
 				    actual_status, status);
-		return;
 	}
 
 	if (!wallet_invoice_delete(wallet, i)) {
 		log_broken(cmd->ld->log,
 			   "Error attempting to remove invoice %"PRIu64,
 			   i.id);
-		command_fail(cmd, LIGHTNINGD, "Database error");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Database error");
 	}
 
 	response = json_stream_success(cmd);
 	json_add_invoice(response, details);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command delinvoice_command = {
@@ -498,7 +496,7 @@ static const struct json_command delinvoice_command = {
 };
 AUTODATA(json_command, &delinvoice_command);
 
-static void json_delexpiredinvoice(struct command *cmd,
+static struct command_result *json_delexpiredinvoice(struct command *cmd,
 						     const char *buffer,
 						     const jsmntok_t *obj UNNEEDED,
 						     const jsmntok_t *params)
@@ -509,11 +507,11 @@ static void json_delexpiredinvoice(struct command *cmd,
 		   p_opt_def("maxexpirytime", param_u64, &maxexpirytime,
 				 time_now().ts.tv_sec),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	wallet_invoice_delete_expired(cmd->ld->wallet, *maxexpirytime);
 
-	command_success(cmd, null_response(cmd));
+	return command_success(cmd, null_response(cmd));
 }
 static const struct json_command delexpiredinvoice_command = {
 	"delexpiredinvoice",
@@ -522,7 +520,7 @@ static const struct json_command delexpiredinvoice_command = {
 };
 AUTODATA(json_command, &delexpiredinvoice_command);
 
-static void json_autocleaninvoice(struct command *cmd,
+static struct command_result *json_autocleaninvoice(struct command *cmd,
 						    const char *buffer,
 						    const jsmntok_t *obj UNNEEDED,
 						    const jsmntok_t *params)
@@ -534,11 +532,11 @@ static void json_autocleaninvoice(struct command *cmd,
 		   p_opt_def("cycle_seconds", param_u64, &cycle, 3600),
 		   p_opt_def("expired_by", param_u64, &exby, 86400),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	wallet_invoice_autoclean(cmd->ld->wallet, *cycle, *exby);
 
-	command_success(cmd, null_response(cmd));
+	return command_success(cmd, null_response(cmd));
 }
 static const struct json_command autocleaninvoice_command = {
 	"autocleaninvoice",
@@ -549,7 +547,7 @@ static const struct json_command autocleaninvoice_command = {
 };
 AUTODATA(json_command, &autocleaninvoice_command);
 
-static void json_waitanyinvoice(struct command *cmd,
+static struct command_result *json_waitanyinvoice(struct command *cmd,
 						  const char *buffer,
 						  const jsmntok_t *obj UNNEEDED,
 						  const jsmntok_t *params)
@@ -560,7 +558,7 @@ static void json_waitanyinvoice(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt_def("lastpay_index", param_u64, &pay_index, 0),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	/* Set command as pending. We do not know if
 	 * wallet_invoice_waitany will return immediately
@@ -570,6 +568,8 @@ static void json_waitanyinvoice(struct command *cmd,
 	/* Find next paid invoice. */
 	wallet_invoice_waitany(cmd, wallet, *pay_index,
 			       &wait_on_invoice, (void*) cmd);
+
+	return command_its_complicated();
 }
 
 static const struct json_command waitanyinvoice_command = {
@@ -585,7 +585,7 @@ AUTODATA(json_command, &waitanyinvoice_command);
  * already been received or it may add the `cmd` to the list of
  * waiters, if the payment is still pending.
  */
-static void json_waitinvoice(struct command *cmd,
+static struct command_result *json_waitinvoice(struct command *cmd,
 					       const char *buffer,
 					       const jsmntok_t *obj UNNEEDED,
 					       const jsmntok_t *params)
@@ -598,23 +598,22 @@ static void json_waitinvoice(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_req("label", param_label, &label),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	if (!wallet_invoice_find_by_label(wallet, &i, label)) {
-		command_fail(cmd, LIGHTNINGD, "Label not found");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Label not found");
 	}
 	details = wallet_invoice_details(cmd, cmd->ld->wallet, i);
 
 	/* If paid or expired return immediately */
 	if (details->state == PAID || details->state == EXPIRED) {
-		tell_waiter(cmd, &i);
-		return;
+		return tell_waiter(cmd, &i);
 	} else {
 		/* There is an unpaid one matching, let's wait... */
 		command_still_pending(cmd);
 		wallet_invoice_waitone(cmd, wallet, i,
 				       &wait_on_invoice, (void *) cmd);
+		return command_its_complicated();
 	}
 }
 
@@ -660,7 +659,7 @@ static void json_add_fallback(struct json_stream *response,
 	json_object_end(response);
 }
 
-static void json_decodepay(struct command *cmd,
+static struct command_result *json_decodepay(struct command *cmd,
 					     const char *buffer,
 					     const jsmntok_t *obj UNNEEDED,
 					     const jsmntok_t *params)
@@ -674,13 +673,12 @@ static void json_decodepay(struct command *cmd,
 		   p_req("bolt11", param_string, &str),
 		   p_opt("description", param_string, &desc),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	b11 = bolt11_decode(cmd, str, desc, &fail);
 
 	if (!b11) {
-		command_fail(cmd, LIGHTNINGD, "Invalid bolt11: %s", fail);
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Invalid bolt11: %s", fail);
 	}
 
 	response = json_stream_success(cmd);
@@ -766,7 +764,7 @@ static void json_decodepay(struct command *cmd,
                         type_to_string(cmd, secp256k1_ecdsa_signature,
                                        &b11->sig));
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command decodepay_command = {

lightningd/jsonrpc.c

@@ -147,7 +147,7 @@ static void destroy_jcon(struct json_connection *jcon)
 	tal_free(jcon->log);
 }
 
-static void json_help(struct command *cmd,
+static struct command_result *json_help(struct command *cmd,
 					const char *buffer,
 					const jsmntok_t *obj UNNEEDED,
 					const jsmntok_t *params);
@@ -166,7 +166,7 @@ static const struct json_command help_command = {
 };
 AUTODATA(json_command, &help_command);
 
-static void json_stop(struct command *cmd,
+static struct command_result *json_stop(struct command *cmd,
 					const char *buffer,
 					const jsmntok_t *obj UNNEEDED,
 					const jsmntok_t *params)
@@ -174,13 +174,13 @@ static void json_stop(struct command *cmd,
 	struct json_stream *response;
 
 	if (!param(cmd, buffer, params, NULL))
-		return;
+		return command_param_failed();
 
 	/* This can't have closed yet! */
 	cmd->jcon->stop = true;
 	response = json_stream_success(cmd);
 	json_add_string(response, NULL, "Shutting down");
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command stop_command = {
@@ -191,7 +191,7 @@ static const struct json_command stop_command = {
 AUTODATA(json_command, &stop_command);
 
 #if DEVELOPER
-static void json_rhash(struct command *cmd,
+static struct command_result *json_rhash(struct command *cmd,
 					 const char *buffer,
 					 const jsmntok_t *obj UNUSED,
 					 const jsmntok_t *params)
@@ -202,7 +202,7 @@ static void json_rhash(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_req("secret", param_sha256, &secret),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	/* Hash in place. */
 	sha256(secret, secret, sizeof(*secret));
@@ -210,7 +210,7 @@ static void json_rhash(struct command *cmd,
 	json_object_start(response, NULL);
 	json_add_hex(response, "rhash", secret, sizeof(*secret));
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command dev_rhash_command = {
@@ -231,7 +231,7 @@ static void slowcmd_finish(struct slowcmd *sc)
 	json_object_start(sc->js, NULL);
 	json_add_num(sc->js, "msec", *sc->msec);
 	json_object_end(sc->js);
-	command_success(sc->cmd, sc->js);
+	was_pending(command_success(sc->cmd, sc->js));
 }
 
 static void slowcmd_start(struct slowcmd *sc)
@@ -241,7 +241,7 @@ static void slowcmd_start(struct slowcmd *sc)
 		     slowcmd_finish, sc);
 }
 
-static void json_slowcmd(struct command *cmd,
+static struct command_result *json_slowcmd(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNUSED,
 					   const jsmntok_t *params)
@@ -252,10 +252,10 @@ static void json_slowcmd(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt_def("msec", param_number, &sc->msec, 1000),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	new_reltimer(&cmd->ld->timers, sc, time_from_msec(0), slowcmd_start, sc);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command dev_slowcmd_command = {
@@ -265,13 +265,13 @@ static const struct json_command dev_slowcmd_command = {
 };
 AUTODATA(json_command, &dev_slowcmd_command);
 
-static void json_crash(struct command *cmd UNUSED,
+static struct command_result *json_crash(struct command *cmd UNUSED,
 					 const char *buffer,
 					 const jsmntok_t *obj UNNEEDED,
 					 const jsmntok_t *params)
 {
 	if (!param(cmd, buffer, params, NULL))
-		return;
+		return command_param_failed();
 
 	fatal("Crash at user request");
 }
@@ -325,7 +325,7 @@ static void json_add_help_command(struct command *cmd,
 
 }
 
-static void json_help(struct command *cmd,
+static struct command_result *json_help(struct command *cmd,
 					const char *buffer,
 					const jsmntok_t *obj UNNEEDED,
 					const jsmntok_t *params)
@@ -337,7 +337,7 @@ static void json_help(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt("command", param_tok, &cmdtok),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	if (cmdtok) {
 		for (size_t i = 0; i < tal_count(commands); i++) {
@@ -347,11 +347,10 @@ static void json_help(struct command *cmd,
 				goto done;
 			}
 		}
-		command_fail(cmd, JSONRPC2_METHOD_NOT_FOUND,
+		return command_fail(cmd, JSONRPC2_METHOD_NOT_FOUND,
 				    "Unknown command '%.*s'",
 				    json_tok_full_len(cmdtok),
 				    json_tok_full(buffer, cmdtok));
-		return;
 	}
 
 	response = json_stream_success(cmd);
@@ -364,7 +363,7 @@ static void json_help(struct command *cmd,
 	json_object_end(response);
 
 done:
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command *find_cmd(const struct jsonrpc *rpc,
@@ -528,15 +527,19 @@ struct json_stream *json_stream_fail(struct command *cmd,
 	return r;
 }
 
-static void parse_request(struct json_connection *jcon, const jsmntok_t tok[])
+/* We return struct command_result so command_fail return value has a natural
+ * sink; we don't actually use the result. */
+static struct command_result *
+parse_request(struct json_connection *jcon, const jsmntok_t tok[])
 {
 	const jsmntok_t *method, *id, *params;
 	struct command *c;
+	struct command_result *res;
 
 	if (tok[0].type != JSMN_OBJECT) {
 		json_command_malformed(jcon, "null",
 				       "Expected {} for json command");
-		return;
+		return NULL;
 	}
 
 	method = json_get_member(jcon->buffer, tok, "method");
@@ -545,12 +548,12 @@ static void parse_request(struct json_connection *jcon, const jsmntok_t tok[])
 
 	if (!id) {
 		json_command_malformed(jcon, "null", "No id");
-		return;
+		return NULL;
 	}
 	if (id->type != JSMN_STRING && id->type != JSMN_PRIMITIVE) {
 		json_command_malformed(jcon, "null",
 				       "Expected string/primitive for id");
-		return;
+		return NULL;
 	}
 
 	/* Allocate the command off of the `jsonrpc` object and not
@@ -568,41 +571,45 @@ static void parse_request(struct json_connection *jcon, const jsmntok_t tok[])
 	tal_add_destructor(c, destroy_command);
 
 	if (!method || !params) {
-		command_fail(c, JSONRPC2_INVALID_REQUEST,
+		return command_fail(c, JSONRPC2_INVALID_REQUEST,
 				    method ? "No params" : "No method");
-		return;
 	}
 
 	if (method->type != JSMN_STRING) {
-		command_fail(c, JSONRPC2_INVALID_REQUEST,
+		return command_fail(c, JSONRPC2_INVALID_REQUEST,
 				    "Expected string for method");
-		return;
 	}
 
         c->json_cmd = find_cmd(jcon->ld->jsonrpc, jcon->buffer, method);
         if (!c->json_cmd) {
-		command_fail(c, JSONRPC2_METHOD_NOT_FOUND,
+		return command_fail(c, JSONRPC2_METHOD_NOT_FOUND,
 				    "Unknown command '%.*s'",
 				    json_tok_full_len(method),
 				    json_tok_full(jcon->buffer, method));
-		return;
 	}
 	if (c->json_cmd->deprecated && !deprecated_apis) {
-		command_fail(c, JSONRPC2_METHOD_NOT_FOUND,
+		return command_fail(c, JSONRPC2_METHOD_NOT_FOUND,
 				    "Command '%.*s' is deprecated",
 				    method->end - method->start,
 				    jcon->buffer + method->start);
-		return;
 	}
 
 	db_begin_transaction(jcon->ld->wallet->db);
-	c->json_cmd->dispatch(c, jcon->buffer, tok, params);
+	res = c->json_cmd->dispatch(c, jcon->buffer, tok, params);
 	db_commit_transaction(jcon->ld->wallet->db);
 
+	assert(res == &param_failed
+	       || res == &complete
+	       || res == &pending
+	       || res == &unknown);
+
 	/* If they didn't complete it, they must call command_still_pending.
 	 * If they completed it, it's freed already. */
+	if (res == &pending)
+		assert(c->pending);
 	list_for_each(&jcon->commands, c, list)
 		assert(c->pending);
+	return res;
 }
 
 /* Mutual recursion */
@@ -1002,7 +1009,7 @@ static void destroy_command_canary(struct command *cmd, bool *failed)
 	*failed = true;
 }
 
-static void json_check(struct command *cmd,
+static struct command_result *json_check(struct command *cmd,
 					 const char *buffer,
 					 const jsmntok_t *obj UNNEEDED,
 					 const jsmntok_t *params)
@@ -1022,7 +1029,7 @@ static void json_check(struct command *cmd,
 		   p_req("command_to_check", param_command, &name_tok),
 		   p_opt_any(),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	/* Point name_tok to the name, not the value */
 	if (params->type == JSMN_OBJECT)
@@ -1036,13 +1043,13 @@ static void json_check(struct command *cmd,
 	cmd->json_cmd->dispatch(cmd, buffer, mod_params, mod_params);
 
 	if (failed)
-		return;
+		return command_its_complicated();
 
 	response = json_stream_success(cmd);
 	json_object_start(response, NULL);
 	json_add_string(response, "command_to_check", cmd->json_cmd->name);
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command check_command = {

lightningd/jsonrpc.h

@@ -49,7 +49,7 @@ struct command_result;
 
 struct json_command {
 	const char *name;
-	void (*dispatch)(struct command *,
+	struct command_result *(*dispatch)(struct command *,
 					   const char *buffer,
 					   const jsmntok_t *obj,
 					   const jsmntok_t *params);

lightningd/log.c

@@ -728,7 +728,7 @@ struct command_result *param_loglevel(struct command *cmd,
 	return NULL;
 }
 
-static void json_getlog(struct command *cmd,
+static struct command_result *json_getlog(struct command *cmd,
 					  const char *buffer,
 					  const jsmntok_t *obj UNNEEDED,
 					  const jsmntok_t * params)
@@ -740,7 +740,7 @@ static void json_getlog(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt_def("level", param_loglevel, &minlevel, LOG_INFORM),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	response = json_stream_success(cmd);
 	json_object_start(response, NULL);
@@ -749,7 +749,7 @@ static void json_getlog(struct command *cmd,
 	json_add_num(response, "bytes_max", (unsigned int) log_max_mem(lr));
 	json_add_log(response, lr, *minlevel);
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command getlog_command = {

lightningd/memdump.c

@@ -62,7 +62,7 @@ static void add_memdump(struct json_stream *response,
 	json_array_end(response);
 }
 
-static void json_memdump(struct command *cmd,
+static struct command_result *json_memdump(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNNEEDED,
 					   const jsmntok_t *params)
@@ -70,12 +70,12 @@ static void json_memdump(struct command *cmd,
 	struct json_stream *response;
 
 	if (!param(cmd, buffer, params, NULL))
-		return;
+		return command_param_failed();
 
 	response = json_stream_success(cmd);
 	add_memdump(response, NULL, NULL, cmd);
 
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command dev_memdump_command = {
@@ -284,18 +284,17 @@ void opening_memleak_done(struct command *cmd, struct subd *leaker)
 	}
 }
 
-static void json_memleak(struct command *cmd,
+static struct command_result *json_memleak(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNNEEDED,
 					   const jsmntok_t *params)
 {
 	if (!param(cmd, buffer, params, NULL))
-		return;
+		return command_param_failed();
 
 	if (!getenv("LIGHTNINGD_DEV_MEMLEAK")) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Leak detection needs $LIGHTNINGD_DEV_MEMLEAK");
-		return;
 	}
 
 	/* For simplicity, we mark pending, though an error may complete it
@@ -304,6 +303,8 @@ static void json_memleak(struct command *cmd,
 
 	/* This calls opening_memleak_done() async when all done. */
 	opening_dev_memleak(cmd);
+
+	return command_its_complicated();
 }
 
 static const struct json_command dev_memleak_command = {

lightningd/opening_control.c

@@ -762,7 +762,7 @@ void opening_peer_no_active_channels(struct peer *peer)
 /**
  * json_fund_channel - Entrypoint for funding a channel
  */
-static void json_fund_channel(struct command *cmd,
+static struct command_result *json_fund_channel(struct command *cmd,
 						const char *buffer,
 						const jsmntok_t *obj UNNEEDED,
 						const jsmntok_t *params)
@@ -787,47 +787,43 @@ static void json_fund_channel(struct command *cmd,
 		   p_opt("feerate", param_feerate, &feerate_per_kw),
 		   p_opt_def("announce", param_bool, &announce_channel, true),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	res = param_wtx(&fc->wtx, buffer, sattok, max_funding_satoshi);
 	if (res)
-		return;
+		return res;
 
 	if (!feerate_per_kw) {
 		feerate_per_kw = tal(cmd, u32);
 		*feerate_per_kw = opening_feerate(cmd->ld->topology);
 		if (!*feerate_per_kw) {
-			command_fail(cmd, LIGHTNINGD, "Cannot estimate fees");
-			return;
+			return command_fail(cmd, LIGHTNINGD,
+					    "Cannot estimate fees");
 		}
 	}
 
 	if (*feerate_per_kw < feerate_floor()) {
-		command_fail(cmd, LIGHTNINGD, "Feerate below feerate floor");
-			return;
+		return command_fail(cmd, LIGHTNINGD,
+				    "Feerate below feerate floor");
 	}
 
 	peer = peer_by_id(cmd->ld, id);
 	if (!peer) {
-		command_fail(cmd, LIGHTNINGD, "Unknown peer");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Unknown peer");
 	}
 
 	channel = peer_active_channel(peer);
 	if (channel) {
-		command_fail(cmd, LIGHTNINGD, "Peer already %s",
+		return command_fail(cmd, LIGHTNINGD, "Peer already %s",
 				    channel_state_name(channel));
-		return;
 	}
 
 	if (!peer->uncommitted_channel) {
-		command_fail(cmd, LIGHTNINGD, "Peer not connected");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Peer not connected");
 	}
 
 	if (peer->uncommitted_channel->fc) {
-		command_fail(cmd, LIGHTNINGD, "Already funding channel");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Already funding channel");
 	}
 
 	/* FIXME: Support push_msat? */
@@ -842,7 +838,7 @@ static void json_fund_channel(struct command *cmd,
 	res = wtx_select_utxos(&fc->wtx, *feerate_per_kw,
 			       BITCOIN_SCRIPTPUBKEY_P2WSH_LEN);
 	if (res)
-		return;
+		return res;
 
 	assert(fc->wtx.amount <= max_funding_satoshi);
 
@@ -862,7 +858,7 @@ static void json_fund_channel(struct command *cmd,
 	/* Openingd will either succeed, or fail, or tell us the other side
 	 * funded first. */
 	subd_send_msg(peer->uncommitted_channel->openingd, take(msg));
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command fund_channel_command = {

lightningd/options.c

@@ -1046,7 +1046,7 @@ static void add_config(struct lightningd *ld,
 	tal_free(name0);
 }
 
-static void json_listconfigs(struct command *cmd,
+static struct command_result *json_listconfigs(struct command *cmd,
 					       const char *buffer,
 					       const jsmntok_t *obj UNNEEDED,
 					       const jsmntok_t *params)
@@ -1058,7 +1058,7 @@ static void json_listconfigs(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt("config", param_tok, &configtok),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	if (!configtok) {
 		response = json_stream_success(cmd);
@@ -1097,14 +1097,13 @@ static void json_listconfigs(struct command *cmd,
 	}
 
 	if (configtok && !response) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "Unknown config option '%.*s'",
 				    json_tok_full_len(configtok),
 				    json_tok_full(buffer, configtok));
-		return;
 	}
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command listconfigs_command = {

lightningd/pay.c

@@ -941,7 +941,7 @@ static void json_sendpay_on_resolve(const struct sendpay_result* r,
 		json_waitsendpay_on_resolve(r, cmd);
 }
 
-static void json_sendpay(struct command *cmd,
+static struct command_result *json_sendpay(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNNEEDED,
 					   const jsmntok_t *params)
@@ -960,7 +960,7 @@ static void json_sendpay(struct command *cmd,
 		   p_opt("description", param_escaped_string, &description),
 		   p_opt("msatoshi", param_u64, &msatoshi),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	end = json_next(routetok);
 	n_hops = 0;
@@ -978,7 +978,7 @@ static void json_sendpay(struct command *cmd,
 			   p_req("delay", param_number, &delay),
 			   p_req("channel", param_short_channel_id, &channel),
 			   NULL))
-			return;
+			return command_param_failed();
 
 		tal_resize(&route, n_hops + 1);
 
@@ -990,8 +990,7 @@ static void json_sendpay(struct command *cmd,
 	}
 
 	if (n_hops == 0) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS, "Empty route");
-		return;
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS, "Empty route");
 	}
 
 	/* The given msatoshi is the actual payment that the payee is
@@ -1002,10 +1001,9 @@ static void json_sendpay(struct command *cmd,
 	if (msatoshi) {
 		if (!(*msatoshi <= route[n_hops-1].amount &&
 		      route[n_hops-1].amount <= 2 * *msatoshi)) {
-			command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 					    "msatoshi %"PRIu64" out of range",
 					    *msatoshi);
-			return;
 		}
 	}
 
@@ -1013,7 +1011,8 @@ static void json_sendpay(struct command *cmd,
 			 msatoshi ? *msatoshi : route[n_hops-1].amount,
 			 description,
 			 &json_sendpay_on_resolve, cmd))
-		command_still_pending(cmd);
+		return command_still_pending(cmd);
+	return command_its_complicated();
 }
 
 static const struct json_command sendpay_command = {
@@ -1028,7 +1027,7 @@ static void waitsendpay_timeout(struct command *cmd)
 	command_fail(cmd, PAY_IN_PROGRESS, "Timed out while waiting");
 }
 
-static void json_waitsendpay(struct command *cmd,
+static struct command_result *json_waitsendpay(struct command *cmd,
 					       const char *buffer,
 					       const jsmntok_t *obj UNNEEDED,
 					       const jsmntok_t *params)
@@ -1040,15 +1039,15 @@ static void json_waitsendpay(struct command *cmd,
 		   p_req("payment_hash", param_sha256, &rhash),
 		   p_opt("timeout", param_number, &timeout),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	if (!wait_payment(cmd, cmd->ld, rhash, &json_waitsendpay_on_resolve, cmd))
-		return;
+		return command_its_complicated();
 
 	if (timeout)
 		new_reltimer(&cmd->ld->timers, cmd, time_from_sec(*timeout),
 			     &waitsendpay_timeout, cmd);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command waitsendpay_command = {
@@ -1059,7 +1058,7 @@ static const struct json_command waitsendpay_command = {
 };
 AUTODATA(json_command, &waitsendpay_command);
 
-static void json_listpayments(struct command *cmd,
+static struct command_result *json_listpayments(struct command *cmd,
 						const char *buffer,
 						const jsmntok_t *obj UNNEEDED,
 						const jsmntok_t *params)
@@ -1073,13 +1072,12 @@ static void json_listpayments(struct command *cmd,
 		   p_opt("bolt11", param_string, &b11str),
 		   p_opt("payment_hash", param_sha256, &rhash),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	if (rhash && b11str) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "Can only specify one of"
 				    " {bolt11} or {payment_hash}");
-		return;
 	}
 
 	if (b11str) {
@@ -1088,9 +1086,8 @@ static void json_listpayments(struct command *cmd,
 
 		b11 = bolt11_decode(cmd, b11str, NULL, &fail);
 		if (!b11) {
-			command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 					    "Invalid bolt11: %s", fail);
-			return;
 		}
 		rhash = &b11->payment_hash;
 	}
@@ -1109,7 +1106,7 @@ static void json_listpayments(struct command *cmd,
 	json_array_end(response);
 
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command listpayments_command = {

lightningd/payalgo.c

@@ -592,7 +592,7 @@ static void json_pay_stop_retrying(struct pay *pay)
 	json_pay_failure(pay, sr);
 }
 
-static void json_pay(struct command *cmd,
+static struct command_result *json_pay(struct command *cmd,
 				       const char *buffer,
 				       const jsmntok_t *obj UNNEEDED,
 				       const jsmntok_t *params)
@@ -619,13 +619,12 @@ static void json_pay(struct command *cmd,
 			     cmd->ld->config.locktime_max),
 		   p_opt_def("exemptfee", param_number, &exemptfee, 5000),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	b11 = bolt11_decode(pay, b11str, desc, &fail);
 	if (!b11) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "Invalid bolt11: %s", fail);
-		return;
 	}
 
 	pay->cmd = cmd;
@@ -638,16 +637,14 @@ static void json_pay(struct command *cmd,
 
 	if (b11->msatoshi) {
 		if (msatoshi) {
-			command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 					    "msatoshi parameter unnecessary");
-			return;
 		}
 		msatoshi = b11->msatoshi;
 	} else {
 		if (!msatoshi) {
-			command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 					    "msatoshi parameter required");
-			return;
 		}
 	}
 	pay->msatoshi = *msatoshi;
@@ -655,12 +652,11 @@ static void json_pay(struct command *cmd,
 	pay->maxfeepercent = *maxfeepercent;
 
 	if (*maxdelay < pay->min_final_cltv_expiry) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "maxdelay (%u) must be greater than "
 				    "min_final_cltv_expiry (%"PRIu32") of "
 				    "invoice",
 				    *maxdelay, pay->min_final_cltv_expiry);
-		return;
 	}
 	pay->maxdelay = *maxdelay;
 
@@ -688,11 +684,12 @@ static void json_pay(struct command *cmd,
 	if (json_pay_try(pay))
 		command_still_pending(cmd);
 	else
-		return;
+		return command_its_complicated();
 
 	/* Set up timeout. */
 	new_reltimer(&cmd->ld->timers, pay, time_from_sec(*retryfor),
 		     &json_pay_stop_retrying, pay);
+	return command_its_complicated();
 }
 
 static const struct json_command pay_command = {

lightningd/peer_control.c

@@ -803,7 +803,7 @@ static void json_add_peer(struct lightningd *ld,
 	json_object_end(response);
 }
 
-static void json_listpeers(struct command *cmd,
+static struct command_result *json_listpeers(struct command *cmd,
 					     const char *buffer,
 					     const jsmntok_t *obj UNNEEDED,
 					     const jsmntok_t *params)
@@ -817,7 +817,7 @@ static void json_listpeers(struct command *cmd,
 		   p_opt("id", param_pubkey, &specific_id),
 		   p_opt("level", param_loglevel, &ll),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	response = json_stream_success(cmd);
 	json_object_start(response, NULL);
@@ -832,7 +832,7 @@ static void json_listpeers(struct command *cmd,
 	}
 	json_array_end(response);
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command listpeers_command = {
@@ -891,7 +891,7 @@ command_find_channel(struct command *cmd,
 	}
 }
 
-static void json_close(struct command *cmd,
+static struct command_result *json_close(struct command *cmd,
 					 const char *buffer,
 					 const jsmntok_t *obj UNNEEDED,
 					 const jsmntok_t *params)
@@ -907,7 +907,7 @@ static void json_close(struct command *cmd,
 		   p_opt_def("force", param_bool, &force, false),
 		   p_opt_def("timeout", param_number, &timeout, 30),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	peer = peer_from_json(cmd->ld, buffer, idtok);
 	if (peer)
@@ -915,7 +915,7 @@ static void json_close(struct command *cmd,
 	else {
 		channel = command_find_channel(cmd, buffer, idtok);
 		if (!channel)
-			return;
+			return command_its_complicated();
 	}
 
 	if (!channel && peer) {
@@ -924,12 +924,10 @@ static void json_close(struct command *cmd,
 			/* Easy case: peer can simply be forgotten. */
 			kill_uncommitted_channel(uc, "close command called");
 
-			command_success(cmd, null_response(cmd));
-			return;
+			return command_success(cmd, null_response(cmd));
 		}
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Peer has no active channel");
-		return;
 	}
 
 	/* Normal case.
@@ -941,9 +939,8 @@ static void json_close(struct command *cmd,
 	    channel->state != CHANNELD_AWAITING_LOCKIN &&
 	    channel->state != CHANNELD_SHUTTING_DOWN &&
 	    channel->state != CLOSINGD_SIGEXCHANGE) {
-		command_fail(cmd, LIGHTNINGD, "Channel is in state %s",
+		return command_fail(cmd, LIGHTNINGD, "Channel is in state %s",
 				    channel_state_name(channel));
-		return;
 	}
 
 	/* If normal or locking in, transition to shutting down
@@ -963,7 +960,7 @@ static void json_close(struct command *cmd,
 	register_close_command(cmd->ld, cmd, channel, *timeout, *force);
 
 	/* Wait until close drops down to chain. */
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command close_command = {
@@ -1035,7 +1032,7 @@ void load_channels_from_wallet(struct lightningd *ld)
 	htlcs_reconnect(ld, &ld->htlcs_in, &ld->htlcs_out);
 }
 
-static void json_disconnect(struct command *cmd,
+static struct command_result *json_disconnect(struct command *cmd,
 					      const char *buffer,
 					      const jsmntok_t *obj UNNEEDED,
 					      const jsmntok_t *params)
@@ -1049,32 +1046,28 @@ static void json_disconnect(struct command *cmd,
 		   p_req("id", param_pubkey, &id),
 		   p_opt_def("force", param_bool, &force, false),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	peer = peer_by_id(cmd->ld, id);
 	if (!peer) {
-		command_fail(cmd, LIGHTNINGD, "Peer not connected");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Peer not connected");
 	}
 	channel = peer_active_channel(peer);
 	if (channel) {
 		if (*force) {
 			channel_fail_transient(channel,
 					       "disconnect command force=true");
-			command_success(cmd, null_response(cmd));
-			return;
+			return command_success(cmd, null_response(cmd));
 		}
-		command_fail(cmd, LIGHTNINGD, "Peer is in state %s",
+		return command_fail(cmd, LIGHTNINGD, "Peer is in state %s",
 				    channel_state_name(channel));
-		return;
 	}
 	if (!peer->uncommitted_channel) {
-		command_fail(cmd, LIGHTNINGD, "Peer not connected");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Peer not connected");
 	}
 	kill_uncommitted_channel(peer->uncommitted_channel,
 				 "disconnect command");
-	command_success(cmd, null_response(cmd));
+	return command_success(cmd, null_response(cmd));
 }
 
 static const struct json_command disconnect_command = {
@@ -1084,7 +1077,7 @@ static const struct json_command disconnect_command = {
 };
 AUTODATA(json_command, &disconnect_command);
 
-static void json_getinfo(struct command *cmd,
+static struct command_result *json_getinfo(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNNEEDED,
 					   const jsmntok_t *params)
@@ -1096,7 +1089,7 @@ static void json_getinfo(struct command *cmd,
             inactive_channels = 0, num_peers = 0;
 
     if (!param(cmd, buffer, params, NULL))
-        return;
+        return command_param_failed();
 
     response = json_stream_success(cmd);
     json_object_start(response, NULL);
@@ -1148,7 +1141,7 @@ static void json_getinfo(struct command *cmd,
     json_add_u64(response, "msatoshi_fees_collected",
              wallet_total_forward_fees(cmd->ld->wallet));
     json_object_end(response);
-    command_success(cmd, response);
+    return command_success(cmd, response);
 }
 
 static const struct json_command getinfo_command = {
@@ -1159,7 +1152,7 @@ static const struct json_command getinfo_command = {
 AUTODATA(json_command, &getinfo_command);
 
 #if DEVELOPER
-static void json_sign_last_tx(struct command *cmd,
+static struct command_result *json_sign_last_tx(struct command *cmd,
 						const char *buffer,
 						const jsmntok_t *obj UNNEEDED,
 						const jsmntok_t *params)
@@ -1173,19 +1166,17 @@ static void json_sign_last_tx(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_req("id", param_pubkey, &peerid),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	peer = peer_by_id(cmd->ld, peerid);
 	if (!peer) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Could not find peer with that id");
-		return;
 	}
 	channel = peer_active_channel(peer);
 	if (!channel) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Could not find active channel");
-		return;
 	}
 
 	response = json_stream_success(cmd);
@@ -1198,7 +1189,7 @@ static void json_sign_last_tx(struct command *cmd,
 	json_object_start(response, NULL);
 	json_add_hex_talarr(response, "tx", linear);
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command dev_sign_last_tx = {
@@ -1208,7 +1199,7 @@ static const struct json_command dev_sign_last_tx = {
 };
 AUTODATA(json_command, &dev_sign_last_tx);
 
-static void json_dev_fail(struct command *cmd,
+static struct command_result *json_dev_fail(struct command *cmd,
 					    const char *buffer,
 					    const jsmntok_t *obj UNNEEDED,
 					    const jsmntok_t *params)
@@ -1220,24 +1211,22 @@ static void json_dev_fail(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_req("id", param_pubkey, &peerid),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	peer = peer_by_id(cmd->ld, peerid);
 	if (!peer) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Could not find peer with that id");
-		return;
 	}
 
 	channel = peer_active_channel(peer);
 	if (!channel) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Could not find active channel with peer");
-		return;
 	}
 
 	channel_internal_error(channel, "Failing due to dev-fail command");
-	command_success(cmd, null_response(cmd));
+	return command_success(cmd, null_response(cmd));
 }
 
 static const struct json_command dev_fail_command = {
@@ -1252,10 +1241,10 @@ static void dev_reenable_commit_finished(struct subd *channeld UNUSED,
 					 const int *fds UNUSED,
 					 struct command *cmd)
 {
-	command_success(cmd, null_response(cmd));
+	was_pending(command_success(cmd, null_response(cmd)));
 }
 
-static void json_dev_reenable_commit(struct command *cmd,
+static struct command_result *json_dev_reenable_commit(struct command *cmd,
 						       const char *buffer,
 						       const jsmntok_t *obj UNNEEDED,
 						       const jsmntok_t *params)
@@ -1268,37 +1257,33 @@ static void json_dev_reenable_commit(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_req("id", param_pubkey, &peerid),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	peer = peer_by_id(cmd->ld, peerid);
 	if (!peer) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Could not find peer with that id");
-		return;
 	}
 
 	channel = peer_active_channel(peer);
 	if (!channel) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Peer has no active channel");
-		return;
 	}
 	if (!channel->owner) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Peer has no owner");
-		return;
 	}
 
 	if (!streq(channel->owner->name, "lightning_channeld")) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Peer owned by %s", channel->owner->name);
-		return;
 	}
 
 	msg = towire_channel_dev_reenable_commit(channel);
 	subd_req(peer, channel->owner, take(msg), -1, 0,
 		 dev_reenable_commit_finished, cmd);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command dev_reenable_commit = {
@@ -1347,7 +1332,7 @@ static void process_dev_forget_channel(struct bitcoind *bitcoind UNUSED,
 	command_success(forget->cmd, response);
 }
 
-static void json_dev_forget_channel(struct command *cmd,
+static struct command_result *json_dev_forget_channel(struct command *cmd,
 						      const char *buffer,
 						      const jsmntok_t *obj UNNEEDED,
 						      const jsmntok_t *params)
@@ -1365,14 +1350,13 @@ static void json_dev_forget_channel(struct command *cmd,
 		   p_opt("short_channel_id", param_short_channel_id, &scid),
 		   p_opt_def("force", param_bool, &force, false),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	forget->force = *force;
 	peer = peer_by_id(cmd->ld, peerid);
 	if (!peer) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Could not find channel with that peer");
-		return;
 	}
 
 	forget->channel = NULL;
@@ -1384,34 +1368,30 @@ static void json_dev_forget_channel(struct command *cmd,
 				continue;
 		}
 		if (forget->channel) {
-			command_fail(cmd, LIGHTNINGD,
+			return command_fail(cmd, LIGHTNINGD,
 					    "Multiple channels:"
 					    " please specify short_channel_id");
-			return;
 		}
 		forget->channel = channel;
 	}
 	if (!forget->channel) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "No channels matching that short_channel_id");
-		return;
 	}
 
 	if (channel_has_htlc_out(forget->channel) ||
 	    channel_has_htlc_in(forget->channel)) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "This channel has HTLCs attached and it is "
 				    "not safe to forget it. Please use `close` "
 				    "or `dev-fail` instead.");
-		return;
-
 	}
 
 	bitcoind_gettxout(cmd->ld->topology->bitcoind,
 			  &forget->channel->funding_txid,
 			  forget->channel->funding_outnum,
 			  process_dev_forget_channel, forget);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command dev_forget_channel_command = {

lightningd/peer_htlcs.c

@@ -1792,7 +1792,7 @@ void htlcs_reconnect(struct lightningd *ld,
 
 
 #if DEVELOPER
-static void json_dev_ignore_htlcs(struct command *cmd,
+static struct command_result *json_dev_ignore_htlcs(struct command *cmd,
 						    const char *buffer,
 						    const jsmntok_t *obj UNNEEDED,
 						    const jsmntok_t *params)
@@ -1805,17 +1805,16 @@ static void json_dev_ignore_htlcs(struct command *cmd,
 		   p_req("id", param_pubkey, &peerid),
 		   p_req("ignore", param_bool, &ignore),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	peer = peer_by_id(cmd->ld, peerid);
 	if (!peer) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Could not find channel with that peer");
-		return;
 	}
 	peer->ignore_htlcs = *ignore;
 
-	command_success(cmd, null_response(cmd));
+	return command_success(cmd, null_response(cmd));
 }
 
 static const struct json_command dev_ignore_htlcs = {
@@ -1849,7 +1848,7 @@ static void listforwardings_add_forwardings(struct json_stream *response, struct
 	tal_free(forwardings);
 }
 
-static void json_listforwards(struct command *cmd,
+static struct command_result *json_listforwards(struct command *cmd,
 						const char *buffer,
 						const jsmntok_t *obj UNNEEDED,
 						const jsmntok_t *params)
@@ -1857,14 +1856,14 @@ static void json_listforwards(struct command *cmd,
 	struct json_stream *response;
 
 	if (!param(cmd, buffer, params, NULL))
-		return;
+		return command_param_failed();
 
 	response = json_stream_success(cmd);
 	json_object_start(response, NULL);
 	listforwardings_add_forwardings(response, cmd->ld->wallet);
 	json_object_end(response);
 
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command listforwards_command = {

lightningd/ping.c

@@ -79,7 +79,7 @@ void ping_reply(struct subd *subd, const u8 *msg)
 	}
 }
 
-static void json_ping(struct command *cmd,
+static struct command_result *json_ping(struct command *cmd,
 					const char *buffer,
 					const jsmntok_t *obj UNNEEDED,
 					const jsmntok_t *params)
@@ -93,7 +93,7 @@ static void json_ping(struct command *cmd,
 		   p_opt_def("len", param_number, &len, 128),
 		   p_opt_def("pongbytes", param_number, &pongbytes, 128),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	/* BOLT #1:
 	 *
@@ -110,16 +110,14 @@ static void json_ping(struct command *cmd,
 	 *    * [`byteslen`:`ignored`]
 	 */
 	if (*len > 65535 - 2 - 2 - 2) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "%u would result in oversize ping", *len);
-		return;
 	}
 
 	/* Note that > 65531 is valid: it means "no pong reply" */
 	if (*pongbytes > 65535) {
-		command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+		return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 				    "pongbytes %u > 65535", *pongbytes);
-		return;
 	}
 
 	/* parent is cmd, so when we complete cmd, we free this. */
@@ -128,7 +126,7 @@ static void json_ping(struct command *cmd,
 	/* gossipd handles all pinging, even if it's in another daemon. */
 	msg = towire_gossip_ping(NULL, id, *pongbytes, *len);
 	subd_send_msg(cmd->ld->gossip, take(msg));
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command ping_command = {

lightningd/plugin.c

@@ -656,7 +656,8 @@ static struct plugin *find_plugin_for_command(struct command *cmd)
 	abort();
 }
 
-static void plugin_rpcmethod_dispatch(struct command *cmd, const char *buffer,
+static struct command_result *plugin_rpcmethod_dispatch(struct command *cmd,
+							const char *buffer,
 							const jsmntok_t *toks,
 							const jsmntok_t *params UNNEEDED)
 {
@@ -668,7 +669,7 @@ static void plugin_rpcmethod_dispatch(struct command *cmd, const char *buffer,
 	if (cmd->mode == CMD_USAGE) {
 		/* FIXME! */
 		cmd->usage = "[params]";
-		return;
+		return command_param_failed();
 	}
 
 	plugin = find_plugin_for_command(cmd);
@@ -683,7 +684,7 @@ static void plugin_rpcmethod_dispatch(struct command *cmd, const char *buffer,
 	json_stream_forward_change_id(req->stream, buffer, toks, idtok, id);
 	plugin_request_queue(plugin, req);
 
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static bool plugin_rpcmethod_add(struct plugin *plugin,

lightningd/test/run-invoice-select-inchan.c

@@ -49,6 +49,12 @@ struct command_result *command_fail(struct command *cmd UNNEEDED, int code UNNEE
 struct command_result *command_failed(struct command *cmd UNNEEDED,
 				      struct json_stream *result UNNEEDED)
 { fprintf(stderr, "command_failed called!\n"); abort(); }
+/* Generated stub for command_its_complicated */
+struct command_result *command_its_complicated(void)
+{ fprintf(stderr, "command_its_complicated called!\n"); abort(); }
+/* Generated stub for command_param_failed */
+struct command_result *command_param_failed(void)
+{ fprintf(stderr, "command_param_failed called!\n"); abort(); }
 /* Generated stub for command_still_pending */
 struct command_result *command_still_pending(struct command *cmd UNNEEDED)
 { fprintf(stderr, "command_still_pending called!\n"); abort(); }

wallet/test/run-wallet.c

@@ -55,6 +55,12 @@ struct command_result *command_fail(struct command *cmd UNNEEDED, int code UNNEE
 				    const char *fmt UNNEEDED, ...)
 
 { fprintf(stderr, "command_fail called!\n"); abort(); }
+/* Generated stub for command_its_complicated */
+struct command_result *command_its_complicated(void)
+{ fprintf(stderr, "command_its_complicated called!\n"); abort(); }
+/* Generated stub for command_param_failed */
+struct command_result *command_param_failed(void)
+{ fprintf(stderr, "command_param_failed called!\n"); abort(); }
 /* Generated stub for command_still_pending */
 struct command_result *command_still_pending(struct command *cmd UNNEEDED)
 { fprintf(stderr, "command_still_pending called!\n"); abort(); }

wallet/walletrpc.c

@@ -85,7 +85,7 @@ static void wallet_withdrawal_broadcast(struct bitcoind *bitcoind UNUSED,
  * request, select coins and a change key. Then send the request to
  * the HSM to generate the signatures.
  */
-static void json_withdraw(struct command *cmd,
+static struct command_result *json_withdraw(struct command *cmd,
 					    const char *buffer,
 					    const jsmntok_t *obj UNNEEDED,
 					    const jsmntok_t *params)
@@ -105,17 +105,17 @@ static void json_withdraw(struct command *cmd,
 		   p_req("satoshi", param_tok, &sattok),
 		   p_opt("feerate", param_feerate, &feerate_per_kw),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	res = param_wtx(&withdraw->wtx, buffer, sattok, -1ULL);
 	if (res)
-		return;
+		return res;
 
 	if (!feerate_per_kw) {
 		res = param_feerate_estimate(cmd, &feerate_per_kw,
 					     FEERATE_NORMAL);
 		if (res)
-			return;
+			return res;
 	}
 
 	/* Parse address. */
@@ -126,22 +126,21 @@ static void json_withdraw(struct command *cmd,
 
 	/* Check that destination address could be understood. */
 	if (addr_parse == ADDRESS_PARSE_UNRECOGNIZED) {
-		command_fail(cmd, LIGHTNINGD, "Could not parse destination address");
-		return;
+		return command_fail(cmd, LIGHTNINGD,
+				    "Could not parse destination address");
 	}
 
 	/* Check address given is compatible with the chain we are on. */
 	if (addr_parse == ADDRESS_PARSE_WRONG_NETWORK) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "Destination address is not on network %s",
 				    get_chainparams(cmd->ld)->network_name);
-		return;
 	}
 
 	res = wtx_select_utxos(&withdraw->wtx, *feerate_per_kw,
 			       tal_count(withdraw->destination));
 	if (res)
-		return;
+		return res;
 
 	u8 *msg = towire_hsm_sign_withdrawal(cmd,
 					     withdraw->wtx.amount,
@@ -164,7 +163,7 @@ static void json_withdraw(struct command *cmd,
 	withdraw->hextx = tal_hex(withdraw, linearize_tx(cmd, tx));
 	bitcoind_sendrawtx(cmd->ld->topology->bitcoind, withdraw->hextx,
 			   wallet_withdrawal_broadcast, withdraw);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command withdraw_command = {
@@ -248,7 +247,7 @@ static struct command_result *param_newaddr(struct command *cmd,
 			    name, tok->end - tok->start, buffer + tok->start);
 }
 
-static void json_newaddr(struct command *cmd,
+static struct command_result *json_newaddr(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNNEEDED,
 					   const jsmntok_t *params)
@@ -263,24 +262,21 @@ static void json_newaddr(struct command *cmd,
 	if (!param(cmd, buffer, params,
 		   p_opt_def("addresstype", param_newaddr, &is_p2wpkh, true),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	keyidx = wallet_get_newindex(cmd->ld);
 	if (keyidx < 0) {
-		command_fail(cmd, LIGHTNINGD, "Keys exhausted ");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Keys exhausted ");
 	}
 
 	if (bip32_key_from_parent(cmd->ld->wallet->bip32_base, keyidx,
 				  BIP32_FLAG_KEY_PUBLIC, &ext) != WALLY_OK) {
-		command_fail(cmd, LIGHTNINGD, "Keys generation failure");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Keys generation failure");
 	}
 
 	if (!secp256k1_ec_pubkey_parse(secp256k1_ctx, &pubkey.pubkey,
 				       ext.pub_key, sizeof(ext.pub_key))) {
-		command_fail(cmd, LIGHTNINGD, "Key parsing failure");
-		return;
+		return command_fail(cmd, LIGHTNINGD, "Key parsing failure");
 	}
 
 	txfilter_add_derkey(cmd->ld->owned_txfilter, ext.pub_key);
@@ -289,16 +285,15 @@ static void json_newaddr(struct command *cmd,
 				    &pubkey, !*is_p2wpkh,
 				    NULL);
 	if (!out) {
-		command_fail(cmd, LIGHTNINGD,
+		return command_fail(cmd, LIGHTNINGD,
 				    "p2wpkh address encoding failure.");
-		return;
 	}
 
 	response = json_stream_success(cmd);
 	json_object_start(response, NULL);
 	json_add_string(response, "address", out);
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command newaddr_command = {
@@ -309,7 +304,7 @@ static const struct json_command newaddr_command = {
 };
 AUTODATA(json_command, &newaddr_command);
 
-static void json_listaddrs(struct command *cmd,
+static struct command_result *json_listaddrs(struct command *cmd,
 					     const char *buffer,
 					     const jsmntok_t *obj UNNEEDED,
 					     const jsmntok_t *params)
@@ -324,7 +319,7 @@ static void json_listaddrs(struct command *cmd,
 				 db_get_intvar(cmd->ld->wallet->db,
 				 "bip32_max_index", 0)),
 		   NULL))
-		return;
+		return command_param_failed();
 
 	response = json_stream_success(cmd);
 	json_object_start(response, NULL);
@@ -377,7 +372,7 @@ static void json_listaddrs(struct command *cmd,
 	}
 	json_array_end(response);
 	json_object_end(response);
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command listaddrs_command = {
@@ -389,7 +384,7 @@ static const struct json_command listaddrs_command = {
 };
 AUTODATA(json_command, &listaddrs_command);
 
-static void json_listfunds(struct command *cmd,
+static struct command_result *json_listfunds(struct command *cmd,
 					     const char *buffer,
 					     const jsmntok_t *obj UNNEEDED,
 					     const jsmntok_t *params)
@@ -401,7 +396,7 @@ static void json_listfunds(struct command *cmd,
 	struct pubkey funding_pubkey;
 
 	if (!param(cmd, buffer, params, NULL))
-		return;
+		return command_param_failed();
 
 	utxos = wallet_get_utxos(cmd, cmd->ld->wallet, output_state_available);
 	response = json_stream_success(cmd);
@@ -422,9 +417,8 @@ static void json_listfunds(struct command *cmd,
 						    utxos[i]->is_p2sh,
 						    NULL);
 			if (!out) {
-				command_fail(cmd, LIGHTNINGD,
+				return command_fail(cmd, LIGHTNINGD,
 						    "p2wpkh address encoding failure.");
-				return;
 			}
 		        json_add_string(response, "address", out);
 		}
@@ -464,7 +458,7 @@ static void json_listfunds(struct command *cmd,
 	json_array_end(response);
 	json_object_end(response);
 
-	command_success(cmd, response);
+	return command_success(cmd, response);
 }
 
 static const struct json_command listfunds_command = {
@@ -517,7 +511,7 @@ static void process_utxo_result(struct bitcoind *bitcoind,
 	}
 }
 
-static void json_dev_rescan_outputs(struct command *cmd,
+static struct command_result *json_dev_rescan_outputs(struct command *cmd,
 						      const char *buffer,
 						      const jsmntok_t *obj UNNEEDED,
 						      const jsmntok_t *params)
@@ -525,7 +519,7 @@ static void json_dev_rescan_outputs(struct command *cmd,
 	struct txo_rescan *rescan = tal(cmd, struct txo_rescan);
 
 	if (!param(cmd, buffer, params, NULL))
-		return;
+		return command_param_failed();
 
 	rescan->response = json_stream_success(cmd);
 	rescan->cmd = cmd;
@@ -537,13 +531,12 @@ static void json_dev_rescan_outputs(struct command *cmd,
 	if (tal_count(rescan->utxos) == 0) {
 		json_array_end(rescan->response);
 		json_object_end(rescan->response);
-		command_success(cmd, rescan->response);
-		return;
+		return command_success(cmd, rescan->response);
 	}
 	bitcoind_gettxout(cmd->ld->topology->bitcoind, &rescan->utxos[0]->txid,
 			  rescan->utxos[0]->outnum, process_utxo_result,
 			  rescan);
-	command_still_pending(cmd);
+	return command_still_pending(cmd);
 }
 
 static const struct json_command dev_rescan_output_command = {