/*
 * netbios.c
 *
 * Copyright (C) 2009-2011 by ipoque GmbH
 * Copyright (C) 2011-18 - ntop.org
 *
 * 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 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_NETBIOS

#include "ndpi_api.h"

struct netbios_header {
    u_int16_t transaction_id, flags, questions, answer_rrs, authority_rrs, additional_rrs;
};

/* The function below has been inherited by tcpdump */
int ndpi_netbios_name_interpret(char *in, char *out, u_int out_len) {
    int ret = 0, len;
    char *b;

    len = (*in++)/2;
    b  = out;
    *out=0;

    if(len > (out_len-1) || len < 1)
        return(-1);

    while (len--) {
        if(in[0] < 'A' || in[0] > 'P' || in[1] < 'A' || in[1] > 'P') {
            *out = 0;
            break;
        }

        *out = ((in[0]-'A')<<4) + (in[1]-'A');

        in += 2;

        if(isprint(*out))
            out++, ret++;
    }

    *out = 0;

    /* Courtesy of Roberto F. De Luca <deluca@tandar.cnea.gov.ar> */
    /* Trim trailing whitespace from the returned string */
    for(out--; out>=b && *out==' '; out--) *out = '\0';

    return(ret);
}

static void ndpi_int_netbios_add_connection(struct ndpi_detection_module_struct
        *ndpi_struct, struct ndpi_flow_struct *flow)
{
    ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_NETBIOS);
}

void ndpi_search_netbios(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
    struct ndpi_packet_struct *packet = &flow->packet;
    u_int16_t dport;
    char name[64];

    NDPI_LOG_DBG(ndpi_struct, "search netbios\n");
    if(packet->udp != NULL) {
        dport = ntohs(packet->udp->dest);


        /*check standard NETBIOS over udp to port 137  */
        if((dport == 137 || 0) && packet->payload_packet_len >= 50) {
            struct netbios_header h;

            memcpy(&h, packet->payload, sizeof(struct netbios_header));
            h.transaction_id = ntohs(h.transaction_id), h.flags = ntohs(h.flags),
                h.questions = ntohs(h.questions), h.answer_rrs = ntohs(h.answer_rrs),
                h.authority_rrs = ntohs(h.authority_rrs), h.additional_rrs = ntohs(h.additional_rrs);

            NDPI_LOG_DBG(ndpi_struct, "found netbios port 137 and payload_packet_len 50\n");

            if(h.flags == 0 &&
                    h.questions == 1 &&
                    h.answer_rrs == 0 &&
                    h.authority_rrs == 0 && h.additional_rrs == 0) {

                NDPI_LOG_INFO(ndpi_struct, "found netbios with questions = 1 and answers = 0, authority = 0  \n");

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }
            if(((h.flags & 0x8710) == 0x10) &&
                    h.questions == 1 &&
                    h.answer_rrs == 0 &&
                    h.authority_rrs == 0) {

                NDPI_LOG_INFO(ndpi_struct, "found netbios with questions = 1 and answers = 0, authority = 0 and broadcast \n");

                if(ndpi_netbios_name_interpret((char*)&packet->payload[12], name, sizeof(name)) > 0) {
                    if(!ndpi_struct->disable_metadata_export) {
                        snprintf((char*)flow->host_server_name, sizeof(flow->host_server_name)-1, "%s", name);
                    }
                }

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }
            if(packet->payload[2] == 0x80 &&
                    h.questions == 1 &&
                    h.answer_rrs == 0 &&
                    h.authority_rrs == 0 && h.additional_rrs == 1) {

                NDPI_LOG_INFO(ndpi_struct, "found netbios with questions = 1 and answers, authority, additional = 0  \n");

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }
            if(h.flags == 0x4000 &&
                    h.questions == 1 &&
                    h.answer_rrs == 0 &&
                    h.authority_rrs == 0 && h.additional_rrs == 1) {

                NDPI_LOG_INFO(ndpi_struct, "found netbios with questions = 1 and answers = 0, authority = 0  \n");

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }
            if(h.flags == 0x8400 &&
                    h.questions == 0 &&
                    h.answer_rrs == 1 &&
                    h.authority_rrs == 0 && h.additional_rrs == 0) {

                NDPI_LOG_INFO(ndpi_struct,
                        "found netbios with flag 8400 questions = 0 and answers = 1, authority, additional = 0  \n");

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }
            if(h.flags == 0x8500 &&
                    h.questions == 0 &&
                    h.answer_rrs == 1 &&
                    h.authority_rrs == 0 && h.additional_rrs == 0) {

                NDPI_LOG_INFO(ndpi_struct,
                        "found netbios with flag 8500 questions = 0 and answers = 1, authority, additional = 0  \n");

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }
            if(h.flags == 0x2910 &&
                    h.questions == 1 &&
                    h.answer_rrs == 0 &&
                    h.authority_rrs == 0 && h.additional_rrs == 1) {

                NDPI_LOG_INFO(ndpi_struct,
                        "found netbios with flag 2910, questions = 1 and answers, authority=0, additional = 1  \n");

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }
            if(h.flags == 0xAD86 &&
                    h.questions == 0 &&
                    h.answer_rrs == 1 &&
                    h.authority_rrs == 0 && h.additional_rrs == 0) {

                NDPI_LOG_INFO(ndpi_struct,
                        "found netbios with flag ad86 questions = 0 and answers = 1, authority, additional = 0  \n");

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }
            if(h.flags == 0x0110 &&
                    h.questions == 1 &&
                    h.answer_rrs == 0 &&
                    h.authority_rrs == 0 && h.additional_rrs == 0) {

                NDPI_LOG_INFO(ndpi_struct,
                        "found netbios with flag 0110 questions = 1 and answers = 0, authority, additional = 0  \n");

                ndpi_int_netbios_add_connection(ndpi_struct, flow);
                return;
            }

            if((h.flags & 0xf800) == 0) {

                NDPI_LOG_DBG2(ndpi_struct, "possible netbios name query request\n");

                if(get_u_int16_t(packet->payload, 4) == htons(1) &&
                        get_u_int16_t(packet->payload, 6) == 0 &&
                        get_u_int16_t(packet->payload, 8) == 0 && get_u_int16_t(packet->payload, 10) == 0) {

                    /* name is encoded as described in rfc883 */
                    u_int8_t name_length = packet->payload[12];

                    NDPI_LOG_DBG2(ndpi_struct,
                            "possible netbios name query request, one question\n");

                    if(packet->payload_packet_len == 12 + 1 + name_length + 1 + 2 + 2) {

                        NDPI_LOG_DBG2(ndpi_struct,
                                "possible netbios name query request, length matches\n");

                        /* null terminated? */
                        if(packet->payload[12 + name_length + 1] == 0 &&
                                get_u_int16_t(packet->payload, 12 + name_length + 2) == htons(0x0020) &&
                                get_u_int16_t(packet->payload, 12 + name_length + 4) == htons(0x0001)) {

                            NDPI_LOG_INFO(ndpi_struct,
                                    "found netbios name query request\n");
                            ndpi_int_netbios_add_connection(ndpi_struct, flow);
                            return;
                        }
                    }
                }
            } else if((h.flags & 0xf800) == 0x8000) {
                NDPI_LOG_DBG2(ndpi_struct,
                        "possible netbios name query response\n");

                if(get_u_int16_t(packet->payload, 4) == 0 &&
                        get_u_int16_t(packet->payload, 6) == htons(1) &&
                        get_u_int16_t(packet->payload, 8) == 0 && get_u_int16_t(packet->payload, 10) == 0) {

                    /* name is encoded as described in rfc883 */
                    u_int8_t name_length = packet->payload[12];

                    NDPI_LOG_DBG2(ndpi_struct,
                            "possible netbios positive name query response, one answer\n");

                    if(packet->payload_packet_len >= 12 + 1 + name_length + 1 + 2 + 2) {

                        NDPI_LOG_DBG2(ndpi_struct,
                                "possible netbios name query response, length matches\n");

                        /* null terminated? */
                        if(packet->payload[12 + name_length + 1] == 0 &&
                                get_u_int16_t(packet->payload, 12 + name_length + 2) == htons(0x0020) &&
                                get_u_int16_t(packet->payload, 12 + name_length + 4) == htons(0x0001)) {

                            NDPI_LOG_INFO(ndpi_struct,
                                    "found netbios name query response\n");
                            ndpi_int_netbios_add_connection(ndpi_struct, flow);
                            return;
                        }
                    }
                } else if(get_u_int16_t(packet->payload, 4) == 0 &&
                        get_u_int16_t(packet->payload, 6) == 0 &&
                        get_u_int16_t(packet->payload, 8) == 0 && get_u_int16_t(packet->payload, 10) == 0) {

                    /* name is encoded as described in rfc883 */
                    u_int8_t name_length = packet->payload[12];

                    NDPI_LOG_DBG2(ndpi_struct,
                            "possible netbios negative name query response, one answer\n");

                    if(packet->payload_packet_len >= 12 + 1 + name_length + 1 + 2 + 2) {

                        NDPI_LOG_DBG2(ndpi_struct,
                                "possible netbios name query response, length matches\n");

                        /* null terminated? */
                        if(packet->payload[12 + name_length + 1] == 0 &&
                                get_u_int16_t(packet->payload, 12 + name_length + 2) == htons(0x000A) &&
                                get_u_int16_t(packet->payload, 12 + name_length + 4) == htons(0x0001)) {

                            NDPI_LOG_INFO(ndpi_struct,
                                    "found netbios name query response\n");
                            ndpi_int_netbios_add_connection(ndpi_struct, flow);
                            return;
                        }
                    }
                } else if(get_u_int16_t(packet->payload, 4) == 0 &&
                        get_u_int16_t(packet->payload, 6) == 0 &&
                        get_u_int16_t(packet->payload, 8) == htons(1) && get_u_int16_t(packet->payload, 10) == htons(1)) {

                    /* name is encoded as described in rfc883 */
                    u_int8_t name_length = packet->payload[12];

                    NDPI_LOG_DBG2(ndpi_struct,
                            "possible netbios redirect name query response, one answer\n");

                    if(packet->payload_packet_len >= 12 + 1 + name_length + 1 + 2 + 2) {

                        NDPI_LOG_DBG2(ndpi_struct,
                                "possible netbios name query response, length matches\n");

                        /* null terminated? */
                        if(packet->payload[12 + name_length + 1] == 0 &&
                                get_u_int16_t(packet->payload, 12 + name_length + 2) == htons(0x0002) &&
                                get_u_int16_t(packet->payload, 12 + name_length + 4) == htons(0x0001)) {

                            NDPI_LOG_INFO(ndpi_struct,
                                    "found netbios name query response\n");
                            ndpi_int_netbios_add_connection(ndpi_struct, flow);
                            return;
                        }
                    }
                }
            }
            /* TODO: extend according to rfc1002 */
        }

        /*check standard NETBIOS over udp to port 138 */

        /*netbios header token from http://www.protocolbase.net/protocols/protocol_NBDGM.php */

        if((dport == 138) &&
                packet->payload_packet_len >= 14 &&
                ntohs(get_u_int16_t(packet->payload, 10)) == packet->payload_packet_len - 14) {

            NDPI_LOG_DBG2(ndpi_struct, "found netbios port 138 and payload length >= 112 \n");

            if(packet->payload[0] >= 0x10 && packet->payload[0] <= 0x16) {
                NDPI_LOG_DBG2(ndpi_struct, "found netbios with MSG-type 0x10,0x11,0x12,0x13,0x14,0x15 or 0x16\n");

                if(ntohl(get_u_int32_t(packet->payload, 4)) == ntohl(packet->iph->saddr)) {
                    NDPI_LOG_INFO(ndpi_struct, "found netbios with checked ip-address\n");

                    if(ndpi_netbios_name_interpret((char*)&packet->payload[12], name, sizeof(name)) > 0) {
                        if(!ndpi_struct->disable_metadata_export) {
                            snprintf((char*)flow->host_server_name, sizeof(flow->host_server_name)-1, "%s", name);
                        }
                    }

                    ndpi_int_netbios_add_connection(ndpi_struct, flow);
                    return;
                }
            }
        }
    }

    if(packet->tcp != NULL) {
        dport = ntohs(packet->tcp->dest);

        /* destination port must be 139 */
        if(dport == 139) {

            NDPI_LOG_DBG2(ndpi_struct, "found netbios with destination port 139\n");

            /* payload_packet_len must be 72 */
            if(packet->payload_packet_len == 72) {
                NDPI_LOG_DBG2(ndpi_struct, "found netbios with payload_packen_len = 72. \n");

                if(packet->payload[0] == 0x81 && packet->payload[1] == 0 && ntohs(get_u_int16_t(packet->payload, 2)) == 68) {
                    NDPI_LOG_INFO(ndpi_struct,
                            "found netbios with session request = 81, flags=0 and length od following bytes = 68. \n");

                    ndpi_int_netbios_add_connection(ndpi_struct, flow);
                    return;
                }
            }
        }

    }

    NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}

void init_netbios_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
    ndpi_set_bitmask_protocol_detection("NETBIOS", ndpi_struct, detection_bitmask, *id,
            NDPI_PROTOCOL_NETBIOS,
            ndpi_search_netbios,
            NDPI_SELECTION_BITMASK_PROTOCOL_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
            SAVE_DETECTION_BITMASK_AS_UNKNOWN,
            ADD_TO_DETECTION_BITMASK);

    *id += 1;
}
