switch to JSON-RPC as message format

Instead of the weird `struct msg` I had, I switched to the JSON-RPC
format. It's basically the same, but has a well-defined semantics in
case of errors.

1 files changed, 256 insertions, 0 deletions

diff --git a/src/json.c b/src/json.c
new file mode 100644
index 0000000..a01aae6
--- /dev/null
+++ b/src/json.c
@@ -0,0 +1,256 @@
+/*
+ * Copyright (c) 2023 Egor Tensin <Egor.Tensin@gmail.com>
+ * This file is part of the "cimple" project.
+ * For details, see https://github.com/egor-tensin/cimple.
+ * Distributed under the MIT License.
+ */
+
+#include "json.h"
+#include "log.h"
+#include "net.h"
+
+#include <json-c/json_object.h>
+#include <json-c/json_tokener.h>
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+char *json_to_string(struct json_object *obj)
+{
+	const char *result = json_object_to_json_string(obj);
+	if (!result) {
+		json_errno("json_object_to_json_string");
+		return NULL;
+	}
+
+	char *_result = strdup(result);
+	if (!_result) {
+		log_errno("strdup");
+		return NULL;
+	}
+
+	return _result;
+}
+
+struct json_object *json_from_string(const char *src)
+{
+	enum json_tokener_error error;
+
+	struct json_object *result = json_tokener_parse_verbose(src, &error);
+	if (!result) {
+		json_errno("json_tokener_parse_verbose");
+		log_err("JSON: parsing failed: %s\n", json_tokener_error_desc(error));
+		return NULL;
+	}
+
+	return result;
+}
+
+int json_clone(const struct json_object *obj, const char *key, struct json_object **_value)
+{
+	int ret = 0;
+
+	struct json_object *old_value = NULL;
+	ret = json_get(obj, key, &old_value);
+	if (ret < 0)
+		return ret;
+
+	struct json_object *new_value = NULL;
+	ret = json_object_deep_copy(old_value, &new_value, NULL);
+	if (ret < 0)
+		return ret;
+
+	*_value = new_value;
+	return ret;
+}
+
+int json_send(struct json_object *obj, int fd)
+{
+	int ret = 0;
+
+	const char *str = json_to_string(obj);
+	if (!str)
+		return -1;
+
+	struct buf *buf = NULL;
+	ret = buf_pack_strings(&buf, 1, &str);
+	free((char *)str);
+	if (ret < 0)
+		return ret;
+
+	ret = net_send_buf(fd, buf);
+	buf_destroy(buf);
+	if (ret < 0)
+		return ret;
+
+	return ret;
+}
+
+struct json_object *json_recv(int fd)
+{
+	struct json_object *result = NULL;
+	int ret = 0;
+
+	struct buf *buf = NULL;
+	ret = net_recv_buf(fd, &buf);
+	if (ret < 0)
+		return NULL;
+
+	result = json_from_string((const char *)buf_get_data(buf));
+	if (!result)
+		goto destroy_buf;
+
+destroy_buf:
+	buf_destroy(buf);
+
+	return result;
+}
+
+int json_has(const struct json_object *obj, const char *key)
+{
+	return json_object_object_get_ex(obj, key, NULL);
+}
+
+int json_get(const struct json_object *obj, const char *key, struct json_object **value)
+{
+	if (!json_has(obj, key)) {
+		log_err("JSON: key is missing: %s\n", key);
+		return -1;
+	}
+
+	return json_object_object_get_ex(obj, key, value);
+}
+
+int json_get_string(const struct json_object *obj, const char *key, const char **_value)
+{
+	struct json_object *value = NULL;
+
+	int ret = json_get(obj, key, &value);
+	if (ret < 0)
+		return ret;
+
+	if (!json_object_is_type(value, json_type_string)) {
+		log_err("JSON: key is not a string: %s\n", key);
+		return -1;
+	}
+
+	*_value = json_object_get_string(value);
+	return 0;
+}
+
+int json_get_int(const struct json_object *obj, const char *key, int64_t *_value)
+{
+	struct json_object *value = NULL;
+
+	int ret = json_get(obj, key, &value);
+	if (ret < 0)
+		return ret;
+
+	if (!json_object_is_type(value, json_type_int)) {
+		log_err("JSON: key is not an integer: %s\n", key);
+		return -1;
+	}
+
+	errno = 0;
+	int64_t tmp = json_object_get_int64(value);
+	if (errno) {
+		log_err("JSON: failed to parse integer from key: %s\n", key);
+		return -1;
+	}
+
+	*_value = tmp;
+	return 0;
+}
+
+static int json_set_internal(struct json_object *obj, const char *key, struct json_object *value,
+                             unsigned flags)
+{
+	int ret = 0;
+
+	ret = json_object_object_add_ex(obj, key, value, flags);
+	if (ret < 0) {
+		json_errno("json_object_object_add_ex");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int json_set_string_internal(struct json_object *obj, const char *key, const char *_value,
+                                    unsigned flags)
+{
+	struct json_object *value = json_object_new_string(_value);
+	if (!value) {
+		json_errno("json_object_new_string");
+		return -1;
+	}
+
+	int ret = json_set_internal(obj, key, value, flags);
+	if (ret < 0)
+		goto free_value;
+
+	return ret;
+
+free_value:
+	json_object_put(value);
+
+	return ret;
+}
+
+static int json_set_int_internal(struct json_object *obj, const char *key, int64_t _value,
+                                 unsigned flags)
+{
+	struct json_object *value = json_object_new_int64(_value);
+	if (!value) {
+		json_errno("json_object_new_int");
+		return -1;
+	}
+
+	int ret = json_set_internal(obj, key, value, flags);
+	if (ret < 0)
+		goto free_value;
+
+	return ret;
+
+free_value:
+	json_object_put(value);
+
+	return ret;
+}
+
+int json_set(struct json_object *obj, const char *key, struct json_object *value)
+{
+	return json_set_internal(obj, key, value, 0);
+}
+
+int json_set_string(struct json_object *obj, const char *key, const char *value)
+{
+	return json_set_string_internal(obj, key, value, 0);
+}
+
+int json_set_int(struct json_object *obj, const char *key, int64_t value)
+{
+	return json_set_int_internal(obj, key, value, 0);
+}
+
+#ifndef JSON_C_OBJECT_ADD_CONSTANT_KEY
+#define JSON_C_OBJECT_ADD_CONSTANT_KEY JSON_C_OBJECT_KEY_IS_CONSTANT
+#endif
+static const unsigned json_const_key_flags = JSON_C_OBJECT_ADD_CONSTANT_KEY;
+
+int json_set_const_key(struct json_object *obj, const char *key, struct json_object *value)
+{
+	return json_set_internal(obj, key, value, json_const_key_flags);
+}
+
+int json_set_string_const_key(struct json_object *obj, const char *key, const char *value)
+{
+	return json_set_string_internal(obj, key, value, json_const_key_flags);
+}
+
+int json_set_int_const_key(struct json_object *obj, const char *key, int64_t value)
+{
+	return json_set_int_internal(obj, key, value, json_const_key_flags);
+}