json-rpc: Add helper for an array of secrets

Suggested-by: Rusty Russell <@rustyrussell>

common/json_tok.c

@@ -324,3 +324,34 @@ struct command_result *param_hops_array(struct command *cmd, const char *name,
 
 	return NULL;
 }
+
+struct command_result *param_secrets_array(struct command *cmd,
+					   const char *name, const char *buffer,
+					   const jsmntok_t *tok,
+					   struct secret **secrets)
+{
+	size_t i;
+	const jsmntok_t *s;
+	struct secret secret;
+
+	if (tok->type != JSMN_ARRAY) {
+		return command_fail(
+		    cmd, JSONRPC2_INVALID_PARAMS,
+		    "'%s' should be an array of secrets, got '%.*s'", name,
+		    tok->end - tok->start, buffer + tok->start);
+	}
+
+	*secrets = tal_arr(cmd, struct secret, 0);
+	json_for_each_arr(i, s, tok) {
+		if (!hex_decode(buffer + s->start, s->end - s->start, &secret,
+				sizeof(secret)))
+			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+					    "'%s[%zu]' should be a 32 byte hex "
+					    "value, not '%.*s'",
+					    name, i, s->end - s->start,
+					    buffer + s->start);
+
+		tal_arr_expand(secrets, secret);
+	}
+	return NULL;
+}

common/json_tok.h

@@ -126,4 +126,9 @@ struct command_result *param_hops_array(struct command *cmd, const char *name,
 					const char *buffer, const jsmntok_t *tok,
 					struct sphinx_hop **hops);
 
+struct command_result *param_secrets_array(struct command *cmd,
+					   const char *name, const char *buffer,
+					   const jsmntok_t *tok,
+					   struct secret **secrets);
+
 #endif /* LIGHTNING_COMMON_JSON_TOK_H */

lightningd/pay.c

@@ -967,16 +967,14 @@ static struct command_result *json_sendonion(struct command *cmd,
 	struct lightningd *ld = cmd->ld;
 	struct wallet_payment *payment;
 	const char *label;
-	const jsmntok_t *secretstok, *cur;
 	struct secret *path_secrets;
-	size_t i;
 
 	if (!param(cmd, buffer, params,
 		   p_req("onion", param_bin_from_hex, &onion),
 		   p_req("first_hop", param_route_hop, &first_hop),
 		   p_req("payment_hash", param_sha256, &payment_hash),
 		   p_opt("label", param_escaped_string, &label),
-		   p_opt("shared_secrets", param_array, &secretstok),
+		   p_opt("shared_secrets", param_secrets_array, &path_secrets),
 		   NULL))
 		return command_param_failed();
 
@@ -988,20 +986,6 @@ static struct command_result *json_sendonion(struct command *cmd,
 				    "with failcode=%d",
 				    failcode);
 
-	if (secretstok) {
-		path_secrets = tal_arr(cmd, struct secret, secretstok->size);
-		json_for_each_arr(i, cur, secretstok) {
-			if (!json_to_secret(buffer, cur, &path_secrets[i]))
-				return command_fail(
-				    cmd, JSONRPC2_INVALID_PARAMS,
-				    "shared_secret[%zu] isn't a valid "
-				    "hex-encoded 32 byte secret",
-				    i);
-		}
-	} else {
-		path_secrets = NULL;
-	}
-
 	/* Now, do we already have a payment? */
 	payment = wallet_payment_by_hash(tmpctx, ld->wallet, payment_hash);
 	if (payment) {