/*
 * whatsapp.c
 *
 * Copyright (C) 2018 - ntop.org
 *
 * nDPI is free software: you can zmqtribute 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 option) 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_WHATSAPP

#include "ndpi_api.h"

void ndpi_search_whatsapp(struct ndpi_detection_module_struct *ndpi_struct,
        struct ndpi_flow_struct *flow) {
    struct ndpi_packet_struct *packet = &flow->packet;
    static u_int8_t whatsapp_sequence[] = {
        0x45, 0x44, 0x0, 0x01, 0x0, 0x0, 0x02, 0x08,
        0x0, 0x57, 0x41, 0x02, 0x0, 0x0, 0x0
    };

    NDPI_LOG_DBG(ndpi_struct, "search WhatsApp\n");

    if(flow->l4.tcp.wa_matched_so_far < sizeof(whatsapp_sequence)) {
        size_t match_len = sizeof(whatsapp_sequence) - flow->l4.tcp.wa_matched_so_far;
        if(packet->payload_packet_len < match_len)
            match_len = packet->payload_packet_len;


        if(!memcmp(packet->payload, &whatsapp_sequence[flow->l4.tcp.wa_matched_so_far], match_len)) {
            flow->l4.tcp.wa_matched_so_far += match_len;
            if(flow->l4.tcp.wa_matched_so_far == sizeof(whatsapp_sequence)) {
                NDPI_LOG_INFO(ndpi_struct, "found WhatsApp\n");
                ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_WHATSAPP);
            }
            return;
        }
    }

    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}

void init_whatsapp_dissector(struct ndpi_detection_module_struct *ndpi_struct,
        u_int32_t *id,
        NDPI_PROTOCOL_BITMASK *detection_bitmask) {

    ndpi_set_bitmask_protocol_detection("WhatsApp", ndpi_struct, detection_bitmask, *id,
            NDPI_PROTOCOL_WHATSAPP,
            ndpi_search_whatsapp,
            NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
            SAVE_DETECTION_BITMASK_AS_UNKNOWN,
            ADD_TO_DETECTION_BITMASK);

    *id += 1;
}
