/*
 * someip.c
 *
 * Copyright (C) 2016 Sorin Zamfir <sorin.zamfir@yahoo.com>
 *
 * This file is part of nDPI, an open source deep packet inspection
 * library based on the OpenDPI and PACE technology by ipoque GmbH
 *
 * nDPI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your omessage_typeion) any later version.
 *
 * nDPI is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with nDPI.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "ndpi_protocol_ids.h"

#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_SOMEIP

#include "ndpi_api.h"

enum SOMEIP_MESSAGE_TYPES {
    SOMEIP_REQUEST = 0x00,
    SOMEIP_REQUEST_NO_RETURN = 0x01,
    SOMEIP_NOTIFICATION = 0x02,
    SOMEIP_REQUEST_ACK = 0x40,
    SOMEIP_REQUEST_NO_RETURN_ACK = 0x41,
    SOMEIP_NOTIFICATION_ACK = 0x42,
    SOMEIP_RESPONSE = 0x80,
    SOMEIP_ERROR = 0x81,
    SOMEIP_RESPONSE_ACK = 0xc0,
    SOMEIP_ERROR_ACK = 0xc1
};

enum SOMEIP_RETURN_CODES {
    E_OK = 0x00,
    E_NOT_OK = 0x01,
    E_UNKNOWN_SERVICE = 0x02,
    E_UNKNOWN_METHOD = 0x03,
    E_NOT_READY = 0x04,
    E_NOT_REACHABLE = 0x05,
    E_TIMEOUT = 0x06,
    E_WRONG_PROTOCOL_VERSION = 0x07,
    E_WRONG_INTERFACE_VERSION = 0x08,
    E_MALFORMED_MESSAGE = 0x09,
    E_WRONG_MESSAGE_TYPE = 0x0a,
    E_RETURN_CODE_LEGAL_THRESHOLD = 0x40  //return codes from 0x40 (inclusive) and upwards are illegal.
};

enum SPECIAL_MESSAGE_IDS {
    MSG_MAGIC_COOKIE = 0xffff0000,
    MSG_MAGIC_COOKIE_ACK = 0xffff8000,
    MSG_SD = 0xffff8100
};

enum PROTOCOL_VERSION{
    LEGAL_PROTOCOL_VERSION = 0x01
};

enum MAGIC_COOKIE_CONSTANTS{
    MC_REQUEST_ID = 0xDEADBEEF,
    MC_LENGTH = 0x08,
    MC_INTERFACE_VERSION = 0x01
};

enum DEFAULT_PROTOCOL_PORTS{
    PORT_DEFAULT_CLIENT = 30491,
    PORT_DEFAULT_SERVER = 30501,
    PORT_DEFAULT_SD = 30490
};

/**
 * Entry point when protocol is identified.
 */
static void ndpi_int_someip_add_connection (struct ndpi_detection_module_struct *ndpi_struct,
        struct ndpi_flow_struct *flow)
{
    NDPI_LOG_INFO(ndpi_struct, "found SOME/IP\n");
    ndpi_set_detected_protocol(ndpi_struct, flow,NDPI_PROTOCOL_SOMEIP);
}

/**
 * Dissector function that searches SOME/IP headers
 */
void ndpi_search_someip (struct ndpi_detection_module_struct *ndpi_struct,
        struct ndpi_flow_struct *flow)
{
    const struct ndpi_packet_struct *packet = &flow->packet;

    if (packet->payload_packet_len < 16) {
        NDPI_LOG(NDPI_PROTOCOL_SOMEIP, ndpi_struct, NDPI_LOG_DEBUG,
                "Excluding SOME/IP .. mandatory header not found (not enough data for all fields)\n");
        NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOMEIP);
        return;
    }

    //####Maybe check carrier protocols?####

    NDPI_LOG_DBG(ndpi_struct, "search SOME/IP\n");

    if (packet->detected_protocol != NDPI_PROTOCOL_UNKNOWN) {
        return;
    }

    //we extract the Message ID and Request ID and check for special cases later
    u_int32_t message_id = ntohl(*((u_int32_t *)&packet->payload[0]));
    u_int32_t request_id = ntohl(*((u_int32_t *)&packet->payload[8]));

    NDPI_LOG_DBG2(ndpi_struct, "====>>>> SOME/IP Message ID: %08x [len: %u]\n",
            message_id, packet->payload_packet_len);
    if (packet->payload_packet_len < 16) {
        NDPI_LOG_DBG(ndpi_struct, "Excluding SOME/IP .. mandatory header not found\n");
        NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOMEIP);
        return;
    }

    //####Maximum packet size in SOMEIP depends on the carrier protocol, and I'm not certain how well enforced it is, so let's leave that for round 2####

    // we extract the remaining length
    u_int32_t someip_len = ntohl(*((u_int32_t *)&packet->payload[4]));
    if (packet->payload_packet_len != (someip_len + 8)) {
        NDPI_LOG_DBG(ndpi_struct, "Excluding SOME/IP .. Length field invalid!\n");
        NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOMEIP);
        return;
    }

    u_int8_t protocol_version = (u_int8_t) (packet->payload[12]);
    NDPI_LOG_DBG2(ndpi_struct,"====>>>> SOME/IP protocol version: [%d]\n",protocol_version);
    if (protocol_version != LEGAL_PROTOCOL_VERSION){
        NDPI_LOG_DBG(ndpi_struct, "Excluding SOME/IP .. invalid protocol version!\n");
        NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOMEIP);
        return;
    }

    u_int8_t interface_version = (packet->payload[13]);

    u_int8_t message_type = (u_int8_t) (packet->payload[14]);
    NDPI_LOG_DBG2(ndpi_struct,"====>>>> SOME/IP message type: [%d]\n",message_type);

    if ((message_type != SOMEIP_REQUEST) && (message_type != SOMEIP_REQUEST_NO_RETURN) && (message_type != SOMEIP_NOTIFICATION) && (message_type != SOMEIP_REQUEST_ACK) &&
            (message_type != SOMEIP_REQUEST_NO_RETURN_ACK) && (message_type != SOMEIP_NOTIFICATION_ACK) && (message_type != SOMEIP_RESPONSE) &&
            (message_type != SOMEIP_ERROR) && (message_type != SOMEIP_RESPONSE_ACK) && (message_type != SOMEIP_ERROR_ACK)) {
        NDPI_LOG_DBG(ndpi_struct, "Excluding SOME/IP .. invalid message type!\n");
        NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOMEIP);
        return;
    }

    u_int8_t return_code = (u_int8_t) (packet->payload[15]);
    NDPI_LOG_DBG2(ndpi_struct,"====>>>> SOME/IP return code: [%d]\n", return_code);
    if ((return_code >= E_RETURN_CODE_LEGAL_THRESHOLD)) {
        NDPI_LOG_DBG(ndpi_struct, "Excluding SOME/IP .. invalid return code!\n");
        NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOMEIP);
        return;
    }

    if (message_id == MSG_MAGIC_COOKIE){
        if ((someip_len == MC_LENGTH) && (request_id == MC_REQUEST_ID) && (interface_version == MC_INTERFACE_VERSION) &&
                (message_type == SOMEIP_REQUEST_NO_RETURN) && (return_code == E_OK)){
            NDPI_LOG_DBG2(ndpi_struct, "found SOME/IP Magic Cookie 0x%x\n",message_type);
            ndpi_int_someip_add_connection(ndpi_struct, flow);
            return;
        }
        else {
            NDPI_LOG_DBG(ndpi_struct, "Excluding SOME/IP, invalid header for Magic Cookie\n");
            NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOMEIP);
            return;
        }
    }

    if (message_id == MSG_MAGIC_COOKIE_ACK){
        if ((someip_len == MC_LENGTH) && (request_id == MC_REQUEST_ID) && (interface_version == MC_INTERFACE_VERSION) &&
                (message_type == SOMEIP_REQUEST_NO_RETURN) && (return_code == E_OK)){
            NDPI_LOG_DBG2(ndpi_struct, "found SOME/IP Magic Cookie ACK 0x%x\n",message_type);
            ndpi_int_someip_add_connection(ndpi_struct, flow);
            return;
        }
        else {
            NDPI_LOG_DBG(ndpi_struct, "Excluding SOME/IP, invalid header for Magic Cookie ACK\n");
            NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SOMEIP);
            return;
        }
    }

    if (message_id == MSG_SD){
        NDPI_LOG_DBG2(ndpi_struct, "SOME/IP-SD currently not supported [%d]\n", message_type);
    }

    // Filtering by port.
    // This check is NOT a 100% thing - these ports are mentioned in the documentation but the documentation also states they haven't been approved by IANA yet, and that the user is free to use different ports.
    // This is is PURELY for demo purposes and the rest of the check must be filled in later on!
    if (packet->l4_protocol == IPPROTO_UDP){
        if ((packet->udp->dest == ntohs(PORT_DEFAULT_CLIENT)) || (packet->udp->dest == ntohs(PORT_DEFAULT_SERVER)) || (packet->udp->dest == ntohs(PORT_DEFAULT_SD))) {
            ndpi_int_someip_add_connection(ndpi_struct, flow);
            return;
        }
    }
    if (packet->l4_protocol == IPPROTO_TCP){
        if ((packet->tcp->dest == ntohs(PORT_DEFAULT_CLIENT)) || (packet->tcp->dest == ntohs(PORT_DEFAULT_SERVER))) {
            ndpi_int_someip_add_connection(ndpi_struct, flow);
            return;
        }
    }

    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
/**
 * Entry point for the ndpi library
 */
void init_someip_dissector (struct ndpi_detection_module_struct *ndpi_struct,
        u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
    ndpi_set_bitmask_protocol_detection ("SOME/IP", ndpi_struct, detection_bitmask, *id,
            NDPI_PROTOCOL_SOMEIP,
            ndpi_search_someip,
            NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD,
            SAVE_DETECTION_BITMASK_AS_UNKNOWN, ADD_TO_DETECTION_BITMASK);
    *id +=1;
}


