subsys/net/lib/ocpp/ocpp_j.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2025 Linumiz GmbH
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #include "ocpp_i.h"
 #include "ocpp_j.h"
 #include <zephyr/data/json.h>
 #include <zephyr/random/random.h>

 static int extract_string_field(char *out_buf, int outlen, char *token)
 {
 	char *end;

 	if (out_buf == NULL || token == NULL) {
 		return -EINVAL;
 	}

 	strncpy(out_buf, token + 1, outlen - 1);
 	end = strchr(out_buf, '"');
 	if (end != NULL) {
 		*end = '\0';
 	}

 	return 0;
 }

 static int extract_payload(char *msg, int msglen)
 {
 	size_t len;
 	char *start = strchr(msg, '{');
 	char *end = strrchr(msg, '}');

 	if (start == NULL || end == NULL || end < start) {
 		return -EINVAL;
 	}

 	len = end - start + 1;
 	if (len >= msglen) {
 		return -ENOMEM;
 	}

 	memmove(msg, start, len);
 	msg[len] = '\0';

 	return 0;
 }

 static int frame_rpc_call_req(char *rpcbuf, int len, int pdu,
 			      uint32_t ses, char *pdumsg)
 {
 	int ret;
 	char uid[JSON_MSG_BUF_128];
 	const char *action;
 	uint32_t rnd = sys_rand32_get();

 	snprintk(uid, sizeof(uid), "%u-%d-%u", ses, pdu, rnd);

 	action = ocpp_get_pdu_literal(pdu);
 	if (action == NULL) {
 		return -EINVAL;
 	}

 	/* Encode OCPP Call Request msg: [2,"<UID>","<Action>",<Payload>] */
 	ret = snprintk(rpcbuf, len,
 		       "[2,\"%s\",\"%s\",%s]",
 		       uid, action, pdumsg);

 	if (ret < 0 || ret >= len) {
 		return -ENOMEM;
 	}

 	return 0;
 }

 static int frame_rpc_call_res(char *rpcbuf, int len,
 			      char *uid, char *pdumsg)
 {
 	int ret;

 	/* Encode OCPP Call Result msg: [3,"<UID>",<Payload>] */
 	ret = snprintk(rpcbuf, len, "[3,\"%s\",%s]", uid, pdumsg);

 	if (ret < 0 || ret >= len) {
 		return -ENOMEM;
 	}

 	return 0;
 }

 static int frame_authorize_msg(char *buf, int len,
 			       struct ocpp_session *ses)
 {
 	int ret;
 	char auth_obj[JSON_MSG_BUF_128];

 	struct json_obj_descr authorize_descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "idTag",
 					  val1, JSON_TOK_STRING),
 	};

 	struct json_common_payload_field_str payload = {
 		.val1 = ses->idtag,
 	};

 	ret = json_obj_encode_buf(authorize_descr,
 				  ARRAY_SIZE(authorize_descr),
 				  &payload,
 				  auth_obj,
 				  sizeof(auth_obj));
 	if (ret < 0) {
 		return ret;
 	}

 	ret = frame_rpc_call_req(buf, len, PDU_AUTHORIZE,
 				 (uintptr_t)ses, auth_obj);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int frame_heartbeat_msg(char *buf, int len, struct ocpp_session *ses)
 {
 	int ret;
 	char tmp_buf[8] = "{}";

 	ret = frame_rpc_call_req(buf, len, PDU_HEARTBEAT,
 				 (uintptr_t)ses, tmp_buf);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int frame_bootnotif_msg(char *buf, int len,
 			       struct ocpp_session *ses,
 			       struct ocpp_cp_info *cpi)
 {
 	int ret;
 	uint8_t descr_count = BOOTNOTIF_MIN_FIELDS;
 	char tmp_buf[JSON_MSG_BUF_512];

 	struct json_ocpp_bootnotif_msg msg = {
 		.charge_point_model = cpi->model,
 		.charge_point_vendor = cpi->vendor,
 		.charge_box_serial_number = cpi->box_sl_no ? cpi->box_sl_no : NULL,
 		.charge_point_serial_number = cpi->sl_no ? cpi->sl_no : NULL,
 		.firmware_version = cpi->fw_ver ? cpi->fw_ver : NULL,
 		.iccid = cpi->iccid ? cpi->iccid : NULL,
 		.imsi = cpi->imsi ? cpi->imsi : NULL,
 		.meter_serial_number = cpi->meter_sl_no ? cpi->meter_sl_no : NULL,
 		.meter_type = cpi->meter_type ? cpi->meter_type : NULL,
 	};

 	struct json_obj_descr bootnotif_descr[BOOTNOTIF_MAX_FIELDS] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "chargePointModel",
 					  charge_point_model, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "chargePointVendor",
 					  charge_point_vendor, JSON_TOK_STRING),
 		};

 	if (msg.charge_box_serial_number != NULL) {
 		bootnotif_descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "chargeBoxSerialNumber",
 					  charge_box_serial_number, JSON_TOK_STRING);
 	}

 	if (msg.charge_point_serial_number != NULL) {
 		bootnotif_descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "chargePointSerialNumber",
 					  charge_point_serial_number, JSON_TOK_STRING);
 	}

 	if (msg.firmware_version != NULL) {
 		bootnotif_descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "firmwareVersion",
 					  firmware_version, JSON_TOK_STRING);
 	}

 	if (msg.iccid != NULL) {
 		bootnotif_descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "iccid",
 					  iccid, JSON_TOK_STRING);
 	}

 	if (msg.imsi != NULL) {
 		bootnotif_descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "imsi",
 					  imsi, JSON_TOK_STRING);
 	}

 	if (msg.meter_serial_number != NULL) {
 		bootnotif_descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "meterSerialNumber",
 					  meter_serial_number, JSON_TOK_STRING);
 	}

 	if (msg.meter_type != NULL) {
 		bootnotif_descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "meterType",
 					  meter_type, JSON_TOK_STRING);
 	}

 	ret = json_obj_encode_buf(bootnotif_descr, descr_count,
 				  &msg, tmp_buf, sizeof(tmp_buf));
 	if (ret < 0) {
 		return ret;
 	}

 	ret = frame_rpc_call_req(buf, len, PDU_BOOTNOTIFICATION,
 				 (uintptr_t)ses, tmp_buf);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int frame_meter_val_msg(char *buf, int len, struct ocpp_session *ses, char *timestamp,
 			       char *val, char *measurand, char *unit)
 {
 	int ret;
 	char tmp_buf[JSON_MSG_BUF_512];
 	uint8_t descr_count = SAMPLED_VALUE_MIN_FIELDS;

 	struct json_ocpp_meter_val_msg msg = {
 		.connector_id = ses ? ses->idcon : 0,
 		.transaction_id = ses ? ses->idtxn : 0,
 		.meter_value = {{
 			.timestamp = timestamp,
 			.sampled_value = {{
 				.measurand = measurand,
 				.value = val,
 				.unit = unit ? unit : NULL,
 			}},
 			.sampled_value_len = 1,
 		}},
 		.meter_value_len = 1,
 	};

 	struct json_obj_descr sampled_value_descr[SAMPLED_VALUE_MAX_FIELDS] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_sample_val, "measurand",
 					  measurand, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_sample_val, "value",
 					  value, JSON_TOK_STRING),
 	};

 	if (msg.meter_value[0].sampled_value[0].unit != NULL) {
 		sampled_value_descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_sample_val, "unit",
 					  unit, JSON_TOK_STRING);
 	}

 	struct json_obj_descr meter_value_descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_meter_val, "timestamp",
 					  timestamp, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_OBJ_ARRAY_NAMED(struct json_ocpp_meter_val, "sampledValue",
 					       sampled_value, 1, sampled_value_len,
 					       sampled_value_descr,
 					       descr_count),
 	};

 	struct json_obj_descr meter_val_msg_descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_meter_val_msg, "connectorId",
 					  connector_id, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_meter_val_msg, "transactionId",
 					  transaction_id, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_OBJ_ARRAY_NAMED(struct json_ocpp_meter_val_msg, "meterValue",
 					       meter_value, 1, meter_value_len,
 					       meter_value_descr,
 					       ARRAY_SIZE(meter_value_descr)),
 	};

 	ret = json_obj_encode_buf(meter_val_msg_descr,
 				  ARRAY_SIZE(meter_val_msg_descr),
 				  &msg, tmp_buf, sizeof(tmp_buf));
 	if (ret < 0) {
 		return ret;
 	}

 	ret = frame_rpc_call_req(buf, len, PDU_METER_VALUES,
 				 (uintptr_t)ses, tmp_buf);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int frame_stop_txn_msg(char *buf, int len, struct ocpp_session *ses,
 			      int Wh, char *reason, char *timestamp)
 {
 	int ret;
 	char tmp_buf[JSON_MSG_BUF_256];
 	uint8_t descr_count = STOP_TXN_MIN_FIELDS;

 	struct json_ocpp_stop_txn_msg msg = {
 		.transaction_id = ses->idtxn,
 		.meter_stop = Wh,
 		.timestamp = timestamp,
 		.reason = reason ? reason : NULL,
 		.id_tag = ses->idtag[0] ? ses->idtag : NULL,
 	};

 	struct json_obj_descr descr[STOP_TXN_MAX_FIELDS] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "transactionId",
 					  transaction_id, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "meterStop",
 					  meter_stop, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "timestamp",
 					  timestamp, JSON_TOK_STRING),
 	};

 	if (msg.reason != NULL) {
 		descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "reason",
 					  reason, JSON_TOK_STRING);
 	}

 	if (msg.id_tag != NULL) {
 		descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "idTag",
 					  id_tag, JSON_TOK_STRING);
 	}

 	ret = json_obj_encode_buf(descr, descr_count, &msg,
 				  tmp_buf, sizeof(tmp_buf));
 	if (ret < 0) {
 		return ret;
 	}

 	ret = frame_rpc_call_req(buf, len, PDU_STOP_TRANSACTION,
 				 (uintptr_t)ses, tmp_buf);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int frame_start_txn_msg(char *buf, int len, struct ocpp_session *ses,
 			       int Wh, int reserv_id, char *timestamp)
 {
 	int ret;
 	char tmp_buf[JSON_MSG_BUF_256];
 	uint8_t descr_count = START_TXN_MIN_FIELDS;

 	struct json_ocpp_start_txn_msg msg = {
 		.connector_id = ses->idcon,
 		.id_tag = ses->idtag,
 		.meter_start = Wh,
 		.timestamp = timestamp,
 		.reservation_id = (reserv_id >= 0) ? reserv_id : -1,
 	};

 	struct json_obj_descr descr[START_TXN_MAX_FIELDS] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "connectorId",
 					  connector_id, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "idTag",
 					  id_tag, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "meterStart",
 					  meter_start, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "timestamp",
 					  timestamp, JSON_TOK_STRING),
 	};

 	if (msg.reservation_id != -1) {
 		descr[descr_count++] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "reservationId",
 					  reservation_id, JSON_TOK_NUMBER);
 	}

 	ret = json_obj_encode_buf(descr, descr_count, &msg,
 				  tmp_buf, sizeof(tmp_buf));
 	if (ret < 0) {
 		return ret;
 	}

 	ret = frame_rpc_call_req(buf, len, PDU_START_TRANSACTION,
 				 (uintptr_t)ses, tmp_buf);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int frame_getconfig_msg(char *buf, int len, char *key, char *val,
 			       bool is_rw, char *uid)
 {
 	int ret;
 	char tmp_buf[JSON_MSG_BUF_128];

 	struct json_ocpp_getconfig_msg msg = { 0 };

 	if (val != NULL) {
 		msg.configuration_key[0].key = key;
 		msg.configuration_key[0].readonly = !is_rw;
 		msg.configuration_key[0].value = val;
 		msg.configuration_key_len = 1;
 	} else {
 		msg.unknown_key = key;
 	}

 	struct json_obj_descr keyval_descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_key_val, "key",
 					  key, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_key_val, "readonly",
 					  readonly, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_key_val, "value",
 					  value, JSON_TOK_STRING),
 	};

 	struct json_obj_descr config_descr[GET_CFG_MAX_FIELDS] = {
 		JSON_OBJ_DESCR_OBJ_ARRAY_NAMED(struct json_ocpp_getconfig_msg, "configurationKey",
 					       configuration_key, 1, configuration_key_len,
 					       keyval_descr, ARRAY_SIZE(keyval_descr))
 	};

 	if (val == NULL) {
 		config_descr[0] = (struct json_obj_descr)
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_getconfig_msg, "unknownKey",
 					  unknown_key, JSON_TOK_STRING);
 	}

 	ret = json_obj_encode_buf(config_descr, GET_CFG_MAX_FIELDS, &msg,
 				  tmp_buf, sizeof(tmp_buf));
 	if (ret < 0) {
 		return ret;
 	}

 	ret = frame_rpc_call_res(buf, len, uid, tmp_buf);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int frame_status_resp_msg(char *buf, int len, char *res, char *uid)
 {
 	int ret;
 	char tmp_buf[JSON_MSG_BUF_128];

 	struct json_obj_descr descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "status",
 					  val1, JSON_TOK_STRING),
 	};

 	struct json_common_payload_field_str msg = {
 		.val1 = res,
 	};

 	ret = json_obj_encode_buf(descr, ARRAY_SIZE(descr), &msg,
 				  tmp_buf, sizeof(tmp_buf));
 	if (ret < 0) {
 		return ret;
 	}

 	ret = frame_rpc_call_res(buf, len, uid, tmp_buf);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 /* parse msg from server */
 int parse_rpc_msg(char *msg, int msglen, char *uid, int uidlen,
 		  int *pdu, bool *is_rsp)
 {
 	int ret;
 	char local_buf[JSON_MSG_BUF_512];
 	char action[JSON_MSG_BUF_128];
 	char *token;
 	char *saveptr = NULL;
 	int rpc_id = -1;

 	if (msg == NULL || uid == NULL || pdu == NULL || is_rsp == NULL) {
 		return -EINVAL;
 	}

 	memcpy(local_buf, msg + 1, sizeof(local_buf) - 1);
 	local_buf[sizeof(local_buf) - 1] = '\0';

 	token = strtok_r(local_buf, ",", &saveptr);
 	if (token == NULL) {
 		return -EINVAL;
 	}

 	rpc_id = *token - '0';

 	token = strtok_r(NULL, ",", &saveptr);
 	if (token == NULL) {
 		return -EINVAL;
 	}

 	ret = extract_string_field(uid, uidlen, token);
 	if (ret < 0) {
 		return ret;
 	}

 	switch (rpc_id + '0') {
 	case OCPP_WAMP_RPC_REQ:
 		token = strtok_r(NULL, ",", &saveptr);
 		if (token == NULL) {
 			return -EINVAL;
 		}

 		ret = extract_string_field(action, sizeof(action), token);
 		if (ret < 0) {
 			return ret;
 		}
 		*pdu = ocpp_find_pdu_from_literal(action);
 		__fallthrough;

 	case OCPP_WAMP_RPC_RESP:
 		*is_rsp = rpc_id - 2;
 		ret = extract_payload(msg, msglen);
 		if (ret < 0) {
 			return ret;
 		}
 		break;

 	case OCPP_WAMP_RPC_ERR:
 		__fallthrough;

 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static int parse_idtag_info(char *json, struct ocpp_idtag_info *idtag_info)
 {
 	int ret;
 	char *status;

 	struct json_obj_descr inner_descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_idtag_info_root, "status",
 					  json_id_tag_info.status, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_idtag_info_root, "parentIdTag",
 					  json_id_tag_info.parent_id_tag, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_idtag_info_root, "expiryDate",
 					  json_id_tag_info.expiry_date, JSON_TOK_STRING),
 	};

 	struct json_obj_descr root_descr[] = {
 		JSON_OBJ_DESCR_OBJECT_NAMED(struct json_idtag_info_root, "idTagInfo",
 					    json_id_tag_info, inner_descr),
 	};

 	struct json_idtag_info_root parsed = { 0 };

 	ret = json_obj_parse(json, strlen(json), root_descr,
 			     ARRAY_SIZE(root_descr), &parsed);
 	if (ret < 0) {
 		return ret;
 	}

 	status = parsed.json_id_tag_info.status;
 	if (status == 0) {
 		return -EINVAL;
 	}

 	switch (*status) {
 	case 'A':
 		idtag_info->auth_status = OCPP_AUTH_ACCEPTED;
 		break;
 	case 'B':
 		idtag_info->auth_status = OCPP_AUTH_BLOCKED;
 		break;
 	case 'E':
 		idtag_info->auth_status = OCPP_AUTH_EXPIRED;
 		break;
 	case 'I':
 		idtag_info->auth_status = OCPP_AUTH_INVALID;
 		break;
 	case 'C':
 		idtag_info->auth_status = OCPP_AUTH_CONCURRENT_TX;
 		break;
 	default:
 		return -EINVAL;
 	}

 	if (parsed.json_id_tag_info.parent_id_tag != NULL) {
 		strncpy(idtag_info->p_idtag, parsed.json_id_tag_info.parent_id_tag,
 			sizeof(idtag_info->p_idtag));
 	}

 	if (parsed.json_id_tag_info.expiry_date != NULL) {
 		strncpy(idtag_info->exptime, parsed.json_id_tag_info.expiry_date,
 			sizeof(idtag_info->exptime));
 	}

 	return 0;
 }

 static int parse_heartbeat_msg(char *json, struct timeval *date)
 {
 	int ret;

 	struct json_obj_descr descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "currentTime",
 					  val1, JSON_TOK_STRING),
 	};

 	struct json_common_payload_field_str heartbeat = {0};

 	ret = json_obj_parse(json, strlen(json), descr,
 			     ARRAY_SIZE(descr), &heartbeat);

 	/* todo: convert civil time to epoch and update local time */

 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int parse_authorize_msg(char *json, struct ocpp_idtag_info *idtag_info)
 {
 	int ret;

 	ret = parse_idtag_info(json, idtag_info);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int parse_bootnotification_msg(char *json, struct boot_notif *binfo)
 {
 	int ret;

 	struct json_obj_descr descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_bootnotif_payload, "status",
 					  status, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_bootnotif_payload, "interval",
 					  interval, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_bootnotif_payload, "currentTime",
 					  current_time, JSON_TOK_STRING),
 	};

 	struct json_bootnotif_payload msg = { 0 };

 	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &msg);
 	if (ret < 0) {
 		return ret;
 	}

 	if (msg.status == NULL) {
 		return -EINVAL;
 	}

 	switch (*msg.status) {
 	case 'A':	/* accepted */
 		binfo->status = BOOT_ACCEPTED;
 		break;
 	case 'P':	/* pending */
 		binfo->status = BOOT_PENDING;
 		break;
 	case 'R':	/* rejected */
 		binfo->status = BOOT_REJECTED;
 		break;
 	default:
 		return -EINVAL;
 	}

 	if (msg.interval == 0) {
 		return -EINVAL;
 	}

 	binfo->interval = msg.interval;

 	if (msg.current_time == NULL) {
 		return -EINVAL;
 	}

 	/* todo: convert civil time to epoch and update local time */
 	(void)binfo->date;

 	return 0;
 }

 static int parse_start_txn_msg(char *json,
 			       int *idtxn,
 			       struct ocpp_idtag_info *idtag_info)
 {
 	int ret;

 	struct json_obj_descr descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "transactionId",
 					  val1, JSON_TOK_NUMBER),
 	};

 	struct json_common_payload_field payload = { 0 };

 	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
 	if (ret < 0) {
 		return ret;
 	}

 	*idtxn = payload.val1;

 	ret = parse_idtag_info(json, idtag_info);
 	if (ret < 0) {
 		return ret;
 	}

 	return 0;
 }

 static int parse_getconfig_msg(char *json, char *key)
 {
 	int ret;

 	struct json_obj_descr descr[] = {
 		JSON_OBJ_DESCR_ARRAY_NAMED(struct json_getconfig_payload, "key",
 					   key, 1, key_len, JSON_TOK_STRING),
 	};

 	struct json_getconfig_payload payload = { 0 };

 	ret = json_obj_parse(json, strlen(json), descr,
 			     ARRAY_SIZE(descr), &payload);
 	if (ret < 0) {
 		return ret;
 	}

 	/* key is optional so return success*/
 	if (payload.key[0] != NULL) {
 		strcpy(key, payload.key[0]);
 	}

 	return 0;
 }

 static int parse_changeconfig_msg(char *json, char *key, char *val)
 {
 	int ret;

 	struct json_obj_descr descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "key",
 					  val1, JSON_TOK_STRING),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "value",
 					  val2, JSON_TOK_STRING),
 	};

 	struct json_common_payload_field_str payload = { 0 };

 	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
 	if (ret < 0) {
 		return ret;
 	}

 	if (payload.val1 == NULL || payload.val2 == NULL) {
 		return -EINVAL;
 	}

 	strncpy(key, payload.val1, CISTR50);
 	strncpy(val, payload.val2, CISTR500);

 	return 0;
 }

 static int parse_remote_start_txn_msg(char *json,
 				      int *idcon,
 				      char *idtag)
 {
 	int ret;

 	struct json_obj_descr descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "connectorId",
 					  val1, JSON_TOK_NUMBER),
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "idTag",
 					  val2, JSON_TOK_STRING),
 	};

 	struct json_common_payload_field payload = { 0 };

 	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
 	if (ret < 0) {
 		return ret;
 	}

 	if (payload.val2 == NULL) {
 		return -EINVAL;
 	}

 	strncpy(idtag, payload.val2, CISTR50);
 	*idcon = payload.val1;

 	return 0;
 }

 static int parse_remote_stop_txn_msg(char *json, int *idtxn)
 {
 	int ret;

 	struct json_obj_descr descr[] = {
 		JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "transactionId",
 					  val1, JSON_TOK_NUMBER),
 	};

 	struct json_common_payload_field payload = { 0 };

 	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
 	if (ret < 0) {
 		return ret;
 	}

 	*idtxn = payload.val1;

 	return 0;
 }

 static int parse_unlock_connectormsg(char *json, int *idcon)
 {
 	int ret;

 	struct json_obj_descr descr[] = {
 	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "connectorId",
 				  val1, JSON_TOK_NUMBER),
 	};

 	struct json_common_payload_field payload = { 0 };

 	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
 	if (ret < 0) {
 		return ret;
 	}

 	if (payload.val1 == 0) {
 		return -EINVAL;
 	}

 	*idcon = payload.val1;

 	return 0;
 }

 static ocpp_msg_fp_t ocpp_json_parser[PDU_MSG_END] = {
 	[PDU_BOOTNOTIFICATION]	= (ocpp_msg_fp_t)parse_bootnotification_msg,
 	[PDU_AUTHORIZE]		= (ocpp_msg_fp_t)parse_authorize_msg,
 	[PDU_START_TRANSACTION]	= (ocpp_msg_fp_t)parse_start_txn_msg,
 	[PDU_STOP_TRANSACTION]	= (ocpp_msg_fp_t)parse_authorize_msg,
 	[PDU_METER_VALUES]	= NULL,
 	[PDU_HEARTBEAT]		= (ocpp_msg_fp_t)parse_heartbeat_msg,
 	[PDU_GET_CONFIGURATION]	= (ocpp_msg_fp_t)parse_getconfig_msg,
 	[PDU_CHANGE_CONFIGURATION]	= (ocpp_msg_fp_t)parse_changeconfig_msg,
 	[PDU_REMOTE_START_TRANSACTION]	= (ocpp_msg_fp_t)parse_remote_start_txn_msg,
 	[PDU_REMOTE_STOP_TRANSACTION]	= (ocpp_msg_fp_t)parse_remote_stop_txn_msg,
 	[PDU_UNLOCK_CONNECTOR]	= (ocpp_msg_fp_t)parse_unlock_connectormsg,
 };

 static ocpp_msg_fp_t ocpp_json_frame[PDU_MSG_END] = {
 	[PDU_BOOTNOTIFICATION]	=  (ocpp_msg_fp_t)frame_bootnotif_msg,
 	[PDU_AUTHORIZE]		=  (ocpp_msg_fp_t)frame_authorize_msg,
 	[PDU_START_TRANSACTION]	=  (ocpp_msg_fp_t)frame_start_txn_msg,
 	[PDU_STOP_TRANSACTION]	=  (ocpp_msg_fp_t)frame_stop_txn_msg,
 	[PDU_METER_VALUES]	=  (ocpp_msg_fp_t)frame_meter_val_msg,
 	[PDU_HEARTBEAT]		=  (ocpp_msg_fp_t)frame_heartbeat_msg,
 	[PDU_GET_CONFIGURATION]	=  (ocpp_msg_fp_t)frame_getconfig_msg,
 	[PDU_CHANGE_CONFIGURATION] (ocpp_msg_fp_t)frame_status_resp_msg,
 	[PDU_REMOTE_START_TRANSACTION]	= (ocpp_msg_fp_t)frame_status_resp_msg,
 	[PDU_REMOTE_STOP_TRANSACTION]	= (ocpp_msg_fp_t)frame_status_resp_msg,
 	[PDU_UNLOCK_CONNECTOR]	= (ocpp_msg_fp_t)frame_status_resp_msg,
 };

 void ocpp_parser_init(ocpp_msg_fp_t **cfn, ocpp_msg_fp_t **pfn)
 {
 	*pfn = ocpp_json_parser;
 	*cfn = ocpp_json_frame;
 }
	/*
	* Copyright (c) 2025 Linumiz GmbH
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#include "ocpp_i.h"
	#include "ocpp_j.h"
	#include <zephyr/data/json.h>
	#include <zephyr/random/random.h>

	static int extract_string_field(char out_buf, int outlen, char token)
	{
	char *end;

	if (out_buf == NULL \|\| token == NULL) {
	return -EINVAL;
	}

	strncpy(out_buf, token + 1, outlen - 1);
	end = strchr(out_buf, '"');
	if (end != NULL) {
	*end = '\0';
	}

	return 0;
	}

	static int extract_payload(char *msg, int msglen)
	{
	size_t len;
	char *start = strchr(msg, '{');
	char *end = strrchr(msg, '}');

	if (start == NULL \|\| end == NULL \|\| end < start) {
	return -EINVAL;
	}

	len = end - start + 1;
	if (len >= msglen) {
	return -ENOMEM;
	}

	memmove(msg, start, len);
	msg[len] = '\0';

	return 0;
	}

	static int frame_rpc_call_req(char *rpcbuf, int len, int pdu,
	uint32_t ses, char *pdumsg)
	{
	int ret;
	char uid[JSON_MSG_BUF_128];
	const char *action;
	uint32_t rnd = sys_rand32_get();

	snprintk(uid, sizeof(uid), "%u-%d-%u", ses, pdu, rnd);

	action = ocpp_get_pdu_literal(pdu);
	if (action == NULL) {
	return -EINVAL;
	}

	/* Encode OCPP Call Request msg: [2,"<UID>","<Action>",<Payload>] */
	ret = snprintk(rpcbuf, len,
	"[2,\"%s\",\"%s\",%s]",
	uid, action, pdumsg);

	if (ret < 0 \|\| ret >= len) {
	return -ENOMEM;
	}

	return 0;
	}

	static int frame_rpc_call_res(char *rpcbuf, int len,
	char uid, char pdumsg)
	{
	int ret;

	/* Encode OCPP Call Result msg: [3,"<UID>",<Payload>] */
	ret = snprintk(rpcbuf, len, "[3,\"%s\",%s]", uid, pdumsg);

	if (ret < 0 \|\| ret >= len) {
	return -ENOMEM;
	}

	return 0;
	}

	static int frame_authorize_msg(char *buf, int len,
	struct ocpp_session *ses)
	{
	int ret;
	char auth_obj[JSON_MSG_BUF_128];

	struct json_obj_descr authorize_descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "idTag",
	val1, JSON_TOK_STRING),
	};

	struct json_common_payload_field_str payload = {
	.val1 = ses->idtag,
	};

	ret = json_obj_encode_buf(authorize_descr,
	ARRAY_SIZE(authorize_descr),
	&payload,
	auth_obj,
	sizeof(auth_obj));
	if (ret < 0) {
	return ret;
	}

	ret = frame_rpc_call_req(buf, len, PDU_AUTHORIZE,
	(uintptr_t)ses, auth_obj);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int frame_heartbeat_msg(char buf, int len, struct ocpp_session ses)
	{
	int ret;
	char tmp_buf[8] = "{}";

	ret = frame_rpc_call_req(buf, len, PDU_HEARTBEAT,
	(uintptr_t)ses, tmp_buf);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int frame_bootnotif_msg(char *buf, int len,
	struct ocpp_session *ses,
	struct ocpp_cp_info *cpi)
	{
	int ret;
	uint8_t descr_count = BOOTNOTIF_MIN_FIELDS;
	char tmp_buf[JSON_MSG_BUF_512];

	struct json_ocpp_bootnotif_msg msg = {
	.charge_point_model = cpi->model,
	.charge_point_vendor = cpi->vendor,
	.charge_box_serial_number = cpi->box_sl_no ? cpi->box_sl_no : NULL,
	.charge_point_serial_number = cpi->sl_no ? cpi->sl_no : NULL,
	.firmware_version = cpi->fw_ver ? cpi->fw_ver : NULL,
	.iccid = cpi->iccid ? cpi->iccid : NULL,
	.imsi = cpi->imsi ? cpi->imsi : NULL,
	.meter_serial_number = cpi->meter_sl_no ? cpi->meter_sl_no : NULL,
	.meter_type = cpi->meter_type ? cpi->meter_type : NULL,
	};

	struct json_obj_descr bootnotif_descr[BOOTNOTIF_MAX_FIELDS] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "chargePointModel",
	charge_point_model, JSON_TOK_STRING),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "chargePointVendor",
	charge_point_vendor, JSON_TOK_STRING),
	};

	if (msg.charge_box_serial_number != NULL) {
	bootnotif_descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "chargeBoxSerialNumber",
	charge_box_serial_number, JSON_TOK_STRING);
	}

	if (msg.charge_point_serial_number != NULL) {
	bootnotif_descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "chargePointSerialNumber",
	charge_point_serial_number, JSON_TOK_STRING);
	}

	if (msg.firmware_version != NULL) {
	bootnotif_descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "firmwareVersion",
	firmware_version, JSON_TOK_STRING);
	}

	if (msg.iccid != NULL) {
	bootnotif_descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "iccid",
	iccid, JSON_TOK_STRING);
	}

	if (msg.imsi != NULL) {
	bootnotif_descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "imsi",
	imsi, JSON_TOK_STRING);
	}

	if (msg.meter_serial_number != NULL) {
	bootnotif_descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "meterSerialNumber",
	meter_serial_number, JSON_TOK_STRING);
	}

	if (msg.meter_type != NULL) {
	bootnotif_descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_bootnotif_msg, "meterType",
	meter_type, JSON_TOK_STRING);
	}

	ret = json_obj_encode_buf(bootnotif_descr, descr_count,
	&msg, tmp_buf, sizeof(tmp_buf));
	if (ret < 0) {
	return ret;
	}

	ret = frame_rpc_call_req(buf, len, PDU_BOOTNOTIFICATION,
	(uintptr_t)ses, tmp_buf);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int frame_meter_val_msg(char buf, int len, struct ocpp_session ses, char *timestamp,
	char val, char measurand, char *unit)
	{
	int ret;
	char tmp_buf[JSON_MSG_BUF_512];
	uint8_t descr_count = SAMPLED_VALUE_MIN_FIELDS;

	struct json_ocpp_meter_val_msg msg = {
	.connector_id = ses ? ses->idcon : 0,
	.transaction_id = ses ? ses->idtxn : 0,
	.meter_value = {{
	.timestamp = timestamp,
	.sampled_value = {{
	.measurand = measurand,
	.value = val,
	.unit = unit ? unit : NULL,
	}},
	.sampled_value_len = 1,
	}},
	.meter_value_len = 1,
	};

	struct json_obj_descr sampled_value_descr[SAMPLED_VALUE_MAX_FIELDS] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_sample_val, "measurand",
	measurand, JSON_TOK_STRING),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_sample_val, "value",
	value, JSON_TOK_STRING),
	};

	if (msg.meter_value[0].sampled_value[0].unit != NULL) {
	sampled_value_descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_sample_val, "unit",
	unit, JSON_TOK_STRING);
	}

	struct json_obj_descr meter_value_descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_meter_val, "timestamp",
	timestamp, JSON_TOK_STRING),
	JSON_OBJ_DESCR_OBJ_ARRAY_NAMED(struct json_ocpp_meter_val, "sampledValue",
	sampled_value, 1, sampled_value_len,
	sampled_value_descr,
	descr_count),
	};

	struct json_obj_descr meter_val_msg_descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_meter_val_msg, "connectorId",
	connector_id, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_meter_val_msg, "transactionId",
	transaction_id, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_OBJ_ARRAY_NAMED(struct json_ocpp_meter_val_msg, "meterValue",
	meter_value, 1, meter_value_len,
	meter_value_descr,
	ARRAY_SIZE(meter_value_descr)),
	};

	ret = json_obj_encode_buf(meter_val_msg_descr,
	ARRAY_SIZE(meter_val_msg_descr),
	&msg, tmp_buf, sizeof(tmp_buf));
	if (ret < 0) {
	return ret;
	}

	ret = frame_rpc_call_req(buf, len, PDU_METER_VALUES,
	(uintptr_t)ses, tmp_buf);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int frame_stop_txn_msg(char buf, int len, struct ocpp_session ses,
	int Wh, char reason, char timestamp)
	{
	int ret;
	char tmp_buf[JSON_MSG_BUF_256];
	uint8_t descr_count = STOP_TXN_MIN_FIELDS;

	struct json_ocpp_stop_txn_msg msg = {
	.transaction_id = ses->idtxn,
	.meter_stop = Wh,
	.timestamp = timestamp,
	.reason = reason ? reason : NULL,
	.id_tag = ses->idtag[0] ? ses->idtag : NULL,
	};

	struct json_obj_descr descr[STOP_TXN_MAX_FIELDS] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "transactionId",
	transaction_id, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "meterStop",
	meter_stop, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "timestamp",
	timestamp, JSON_TOK_STRING),
	};

	if (msg.reason != NULL) {
	descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "reason",
	reason, JSON_TOK_STRING);
	}

	if (msg.id_tag != NULL) {
	descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_stop_txn_msg, "idTag",
	id_tag, JSON_TOK_STRING);
	}

	ret = json_obj_encode_buf(descr, descr_count, &msg,
	tmp_buf, sizeof(tmp_buf));
	if (ret < 0) {
	return ret;
	}

	ret = frame_rpc_call_req(buf, len, PDU_STOP_TRANSACTION,
	(uintptr_t)ses, tmp_buf);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int frame_start_txn_msg(char buf, int len, struct ocpp_session ses,
	int Wh, int reserv_id, char *timestamp)
	{
	int ret;
	char tmp_buf[JSON_MSG_BUF_256];
	uint8_t descr_count = START_TXN_MIN_FIELDS;

	struct json_ocpp_start_txn_msg msg = {
	.connector_id = ses->idcon,
	.id_tag = ses->idtag,
	.meter_start = Wh,
	.timestamp = timestamp,
	.reservation_id = (reserv_id >= 0) ? reserv_id : -1,
	};

	struct json_obj_descr descr[START_TXN_MAX_FIELDS] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "connectorId",
	connector_id, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "idTag",
	id_tag, JSON_TOK_STRING),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "meterStart",
	meter_start, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "timestamp",
	timestamp, JSON_TOK_STRING),
	};

	if (msg.reservation_id != -1) {
	descr[descr_count++] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_start_txn_msg, "reservationId",
	reservation_id, JSON_TOK_NUMBER);
	}

	ret = json_obj_encode_buf(descr, descr_count, &msg,
	tmp_buf, sizeof(tmp_buf));
	if (ret < 0) {
	return ret;
	}

	ret = frame_rpc_call_req(buf, len, PDU_START_TRANSACTION,
	(uintptr_t)ses, tmp_buf);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int frame_getconfig_msg(char buf, int len, char key, char *val,
	bool is_rw, char *uid)
	{
	int ret;
	char tmp_buf[JSON_MSG_BUF_128];

	struct json_ocpp_getconfig_msg msg = { 0 };

	if (val != NULL) {
	msg.configuration_key[0].key = key;
	msg.configuration_key[0].readonly = !is_rw;
	msg.configuration_key[0].value = val;
	msg.configuration_key_len = 1;
	} else {
	msg.unknown_key = key;
	}

	struct json_obj_descr keyval_descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_key_val, "key",
	key, JSON_TOK_STRING),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_key_val, "readonly",
	readonly, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_key_val, "value",
	value, JSON_TOK_STRING),
	};

	struct json_obj_descr config_descr[GET_CFG_MAX_FIELDS] = {
	JSON_OBJ_DESCR_OBJ_ARRAY_NAMED(struct json_ocpp_getconfig_msg, "configurationKey",
	configuration_key, 1, configuration_key_len,
	keyval_descr, ARRAY_SIZE(keyval_descr))
	};

	if (val == NULL) {
	config_descr[0] = (struct json_obj_descr)
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_ocpp_getconfig_msg, "unknownKey",
	unknown_key, JSON_TOK_STRING);
	}

	ret = json_obj_encode_buf(config_descr, GET_CFG_MAX_FIELDS, &msg,
	tmp_buf, sizeof(tmp_buf));
	if (ret < 0) {
	return ret;
	}

	ret = frame_rpc_call_res(buf, len, uid, tmp_buf);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int frame_status_resp_msg(char buf, int len, char res, char *uid)
	{
	int ret;
	char tmp_buf[JSON_MSG_BUF_128];

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "status",
	val1, JSON_TOK_STRING),
	};

	struct json_common_payload_field_str msg = {
	.val1 = res,
	};

	ret = json_obj_encode_buf(descr, ARRAY_SIZE(descr), &msg,
	tmp_buf, sizeof(tmp_buf));
	if (ret < 0) {
	return ret;
	}

	ret = frame_rpc_call_res(buf, len, uid, tmp_buf);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	/* parse msg from server */
	int parse_rpc_msg(char msg, int msglen, char uid, int uidlen,
	int pdu, bool is_rsp)
	{
	int ret;
	char local_buf[JSON_MSG_BUF_512];
	char action[JSON_MSG_BUF_128];
	char *token;
	char *saveptr = NULL;
	int rpc_id = -1;

	if (msg == NULL \|\| uid == NULL \|\| pdu == NULL \|\| is_rsp == NULL) {
	return -EINVAL;
	}

	memcpy(local_buf, msg + 1, sizeof(local_buf) - 1);
	local_buf[sizeof(local_buf) - 1] = '\0';

	token = strtok_r(local_buf, ",", &saveptr);
	if (token == NULL) {
	return -EINVAL;
	}

	rpc_id = *token - '0';

	token = strtok_r(NULL, ",", &saveptr);
	if (token == NULL) {
	return -EINVAL;
	}

	ret = extract_string_field(uid, uidlen, token);
	if (ret < 0) {
	return ret;
	}

	switch (rpc_id + '0') {
	case OCPP_WAMP_RPC_REQ:
	token = strtok_r(NULL, ",", &saveptr);
	if (token == NULL) {
	return -EINVAL;
	}

	ret = extract_string_field(action, sizeof(action), token);
	if (ret < 0) {
	return ret;
	}
	*pdu = ocpp_find_pdu_from_literal(action);
	__fallthrough;

	case OCPP_WAMP_RPC_RESP:
	*is_rsp = rpc_id - 2;
	ret = extract_payload(msg, msglen);
	if (ret < 0) {
	return ret;
	}
	break;

	case OCPP_WAMP_RPC_ERR:
	__fallthrough;

	default:
	return -EINVAL;
	}

	return 0;
	}

	static int parse_idtag_info(char json, struct ocpp_idtag_info idtag_info)
	{
	int ret;
	char *status;

	struct json_obj_descr inner_descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_idtag_info_root, "status",
	json_id_tag_info.status, JSON_TOK_STRING),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_idtag_info_root, "parentIdTag",
	json_id_tag_info.parent_id_tag, JSON_TOK_STRING),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_idtag_info_root, "expiryDate",
	json_id_tag_info.expiry_date, JSON_TOK_STRING),
	};

	struct json_obj_descr root_descr[] = {
	JSON_OBJ_DESCR_OBJECT_NAMED(struct json_idtag_info_root, "idTagInfo",
	json_id_tag_info, inner_descr),
	};

	struct json_idtag_info_root parsed = { 0 };

	ret = json_obj_parse(json, strlen(json), root_descr,
	ARRAY_SIZE(root_descr), &parsed);
	if (ret < 0) {
	return ret;
	}

	status = parsed.json_id_tag_info.status;
	if (status == 0) {
	return -EINVAL;
	}

	switch (*status) {
	case 'A':
	idtag_info->auth_status = OCPP_AUTH_ACCEPTED;
	break;
	case 'B':
	idtag_info->auth_status = OCPP_AUTH_BLOCKED;
	break;
	case 'E':
	idtag_info->auth_status = OCPP_AUTH_EXPIRED;
	break;
	case 'I':
	idtag_info->auth_status = OCPP_AUTH_INVALID;
	break;
	case 'C':
	idtag_info->auth_status = OCPP_AUTH_CONCURRENT_TX;
	break;
	default:
	return -EINVAL;
	}

	if (parsed.json_id_tag_info.parent_id_tag != NULL) {
	strncpy(idtag_info->p_idtag, parsed.json_id_tag_info.parent_id_tag,
	sizeof(idtag_info->p_idtag));
	}

	if (parsed.json_id_tag_info.expiry_date != NULL) {
	strncpy(idtag_info->exptime, parsed.json_id_tag_info.expiry_date,
	sizeof(idtag_info->exptime));
	}

	return 0;
	}

	static int parse_heartbeat_msg(char json, struct timeval date)
	{
	int ret;

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "currentTime",
	val1, JSON_TOK_STRING),
	};

	struct json_common_payload_field_str heartbeat = {0};

	ret = json_obj_parse(json, strlen(json), descr,
	ARRAY_SIZE(descr), &heartbeat);

	/* todo: convert civil time to epoch and update local time */

	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int parse_authorize_msg(char json, struct ocpp_idtag_info idtag_info)
	{
	int ret;

	ret = parse_idtag_info(json, idtag_info);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int parse_bootnotification_msg(char json, struct boot_notif binfo)
	{
	int ret;

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_bootnotif_payload, "status",
	status, JSON_TOK_STRING),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_bootnotif_payload, "interval",
	interval, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_bootnotif_payload, "currentTime",
	current_time, JSON_TOK_STRING),
	};

	struct json_bootnotif_payload msg = { 0 };

	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &msg);
	if (ret < 0) {
	return ret;
	}

	if (msg.status == NULL) {
	return -EINVAL;
	}

	switch (*msg.status) {
	case 'A': /* accepted */
	binfo->status = BOOT_ACCEPTED;
	break;
	case 'P': /* pending */
	binfo->status = BOOT_PENDING;
	break;
	case 'R': /* rejected */
	binfo->status = BOOT_REJECTED;
	break;
	default:
	return -EINVAL;
	}

	if (msg.interval == 0) {
	return -EINVAL;
	}

	binfo->interval = msg.interval;

	if (msg.current_time == NULL) {
	return -EINVAL;
	}

	/* todo: convert civil time to epoch and update local time */
	(void)binfo->date;

	return 0;
	}

	static int parse_start_txn_msg(char *json,
	int *idtxn,
	struct ocpp_idtag_info *idtag_info)
	{
	int ret;

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "transactionId",
	val1, JSON_TOK_NUMBER),
	};

	struct json_common_payload_field payload = { 0 };

	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
	if (ret < 0) {
	return ret;
	}

	*idtxn = payload.val1;

	ret = parse_idtag_info(json, idtag_info);
	if (ret < 0) {
	return ret;
	}

	return 0;
	}

	static int parse_getconfig_msg(char json, char key)
	{
	int ret;

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_ARRAY_NAMED(struct json_getconfig_payload, "key",
	key, 1, key_len, JSON_TOK_STRING),
	};

	struct json_getconfig_payload payload = { 0 };

	ret = json_obj_parse(json, strlen(json), descr,
	ARRAY_SIZE(descr), &payload);
	if (ret < 0) {
	return ret;
	}

	/* key is optional so return success*/
	if (payload.key[0] != NULL) {
	strcpy(key, payload.key[0]);
	}

	return 0;
	}

	static int parse_changeconfig_msg(char json, char key, char *val)
	{
	int ret;

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "key",
	val1, JSON_TOK_STRING),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field_str, "value",
	val2, JSON_TOK_STRING),
	};

	struct json_common_payload_field_str payload = { 0 };

	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
	if (ret < 0) {
	return ret;
	}

	if (payload.val1 == NULL \|\| payload.val2 == NULL) {
	return -EINVAL;
	}

	strncpy(key, payload.val1, CISTR50);
	strncpy(val, payload.val2, CISTR500);

	return 0;
	}

	static int parse_remote_start_txn_msg(char *json,
	int *idcon,
	char *idtag)
	{
	int ret;

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "connectorId",
	val1, JSON_TOK_NUMBER),
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "idTag",
	val2, JSON_TOK_STRING),
	};

	struct json_common_payload_field payload = { 0 };

	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
	if (ret < 0) {
	return ret;
	}

	if (payload.val2 == NULL) {
	return -EINVAL;
	}

	strncpy(idtag, payload.val2, CISTR50);
	*idcon = payload.val1;

	return 0;
	}

	static int parse_remote_stop_txn_msg(char json, int idtxn)
	{
	int ret;

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "transactionId",
	val1, JSON_TOK_NUMBER),
	};

	struct json_common_payload_field payload = { 0 };

	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
	if (ret < 0) {
	return ret;
	}

	*idtxn = payload.val1;

	return 0;
	}

	static int parse_unlock_connectormsg(char json, int idcon)
	{
	int ret;

	struct json_obj_descr descr[] = {
	JSON_OBJ_DESCR_PRIM_NAMED(struct json_common_payload_field, "connectorId",
	val1, JSON_TOK_NUMBER),
	};

	struct json_common_payload_field payload = { 0 };

	ret = json_obj_parse(json, strlen(json), descr, ARRAY_SIZE(descr), &payload);
	if (ret < 0) {
	return ret;
	}

	if (payload.val1 == 0) {
	return -EINVAL;
	}

	*idcon = payload.val1;

	return 0;
	}

	static ocpp_msg_fp_t ocpp_json_parser[PDU_MSG_END] = {
	[PDU_BOOTNOTIFICATION] = (ocpp_msg_fp_t)parse_bootnotification_msg,
	[PDU_AUTHORIZE] = (ocpp_msg_fp_t)parse_authorize_msg,
	[PDU_START_TRANSACTION] = (ocpp_msg_fp_t)parse_start_txn_msg,
	[PDU_STOP_TRANSACTION] = (ocpp_msg_fp_t)parse_authorize_msg,
	[PDU_METER_VALUES] = NULL,
	[PDU_HEARTBEAT] = (ocpp_msg_fp_t)parse_heartbeat_msg,
	[PDU_GET_CONFIGURATION] = (ocpp_msg_fp_t)parse_getconfig_msg,
	[PDU_CHANGE_CONFIGURATION] = (ocpp_msg_fp_t)parse_changeconfig_msg,
	[PDU_REMOTE_START_TRANSACTION] = (ocpp_msg_fp_t)parse_remote_start_txn_msg,
	[PDU_REMOTE_STOP_TRANSACTION] = (ocpp_msg_fp_t)parse_remote_stop_txn_msg,
	[PDU_UNLOCK_CONNECTOR] = (ocpp_msg_fp_t)parse_unlock_connectormsg,
	};

	static ocpp_msg_fp_t ocpp_json_frame[PDU_MSG_END] = {
	[PDU_BOOTNOTIFICATION] = (ocpp_msg_fp_t)frame_bootnotif_msg,
	[PDU_AUTHORIZE] = (ocpp_msg_fp_t)frame_authorize_msg,
	[PDU_START_TRANSACTION] = (ocpp_msg_fp_t)frame_start_txn_msg,
	[PDU_STOP_TRANSACTION] = (ocpp_msg_fp_t)frame_stop_txn_msg,
	[PDU_METER_VALUES] = (ocpp_msg_fp_t)frame_meter_val_msg,
	[PDU_HEARTBEAT] = (ocpp_msg_fp_t)frame_heartbeat_msg,
	[PDU_GET_CONFIGURATION] = (ocpp_msg_fp_t)frame_getconfig_msg,
	[PDU_CHANGE_CONFIGURATION] (ocpp_msg_fp_t)frame_status_resp_msg,
	[PDU_REMOTE_START_TRANSACTION] = (ocpp_msg_fp_t)frame_status_resp_msg,
	[PDU_REMOTE_STOP_TRANSACTION] = (ocpp_msg_fp_t)frame_status_resp_msg,
	[PDU_UNLOCK_CONNECTOR] = (ocpp_msg_fp_t)frame_status_resp_msg,
	};

	void ocpp_parser_init(ocpp_msg_fp_t cfn, ocpp_msg_fp_t pfn)
	{
	*pfn = ocpp_json_parser;
	*cfn = ocpp_json_frame;
	}