common: add param_channel_type helper.

We use an array of bit numbers.  We could use an array of names, but the JSON typing is then harder.

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

common/Makefile

@@ -54,6 +54,7 @@ COMMON_SRC_NOGEN :=				\
 	common/initial_commit_tx.c		\
 	common/invoice_path_id.c		\
 	common/iso4217.c			\
+	common/json_channel_type.c		\
 	common/json_filter.c			\
 	common/json_param.c			\
 	common/json_parse.c			\

common/json_channel_type.c

@@ -0,0 +1,32 @@
+#include "config.h"
+#include <common/channel_type.h>
+#include <common/json_channel_type.h>
+#include <common/json_command.h>
+#include <common/json_param.h>
+
+struct command_result *param_channel_type(struct command *cmd,
+					  const char *name,
+					  const char *buffer,
+					  const jsmntok_t *tok,
+					  struct channel_type **ctype)
+{
+	u8 *features = tal_arr(NULL, u8, 0);
+	size_t i;
+	const jsmntok_t *t;
+
+	if (tok->type != JSMN_ARRAY) {
+		return command_fail_badparam(cmd, name, buffer, tok,
+					     "must be an array");
+	}
+
+	json_for_each_arr(i, t, tok) {
+		u16 fbit;
+		if (!json_to_u16(buffer, t, &fbit))
+			return command_fail_badparam(cmd, name, buffer, t,
+						     "must be a 16-bit integer");
+		set_feature_bit(&features, fbit);
+	}
+
+	*ctype = channel_type_from(cmd, take(features));
+	return NULL;
+}

common/json_channel_type.h

@@ -0,0 +1,17 @@
+/* Dealing with channel_type in JSON */
+#ifndef LIGHTNING_COMMON_JSON_CHANNEL_TYPE_H
+#define LIGHTNING_COMMON_JSON_CHANNEL_TYPE_H
+#include "config.h"
+#include <common/json_parse_simple.h>
+
+struct command;
+struct channel_type;
+
+/* Parse [1,2] as a channel_type */
+struct command_result *param_channel_type(struct command *cmd,
+					  const char *name,
+					  const char *buffer,
+					  const jsmntok_t *tok,
+					  struct channel_type **ctype);
+
+#endif /* LIGHTNING_COMMON_JSON_CHANNEL_TYPE_H */