/*
 * ssh.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_SSH

#include "ndpi_api.h"

static void ndpi_int_ssh_add_connection(struct ndpi_detection_module_struct
        *ndpi_struct, struct ndpi_flow_struct *flow){
    ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SSH);
}

static void ndpi_ssh_zap_cr(char *str, int len) {
    len--;

    while(len > 0) {
        if((str[len] == '\n') || (str[len] == '\r')) {
            str[len] = '\0';
            len--;
        } else
            break;
    }
}

void ndpi_search_ssh_tcp(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
    struct ndpi_packet_struct *packet = &flow->packet;

    if (flow->l4.tcp.ssh_stage == 0) {
        if (packet->payload_packet_len > 7 && packet->payload_packet_len < 100
                && memcmp(packet->payload, "SSH-", 4) == 0) {
            if(!ndpi_struct->disable_metadata_export) {
                int len = ndpi_min(sizeof(flow->protos.ssh.client_signature)-1, packet->payload_packet_len);
                strncpy(flow->protos.ssh.client_signature, (const char *)packet->payload, len);
                flow->protos.ssh.client_signature[len] = '\0';
                ndpi_ssh_zap_cr(flow->protos.ssh.client_signature, len);
            }

            NDPI_LOG_DBG2(ndpi_struct, "ssh stage 0 passed\n");
            flow->l4.tcp.ssh_stage = 1 + packet->packet_direction;
            return;
        }
    } else if (flow->l4.tcp.ssh_stage == (2 - packet->packet_direction)) {
        if (packet->payload_packet_len > 7 && packet->payload_packet_len < 500
                && memcmp(packet->payload, "SSH-", 4) == 0) {
            if(!ndpi_struct->disable_metadata_export) {
                int len = ndpi_min(sizeof(flow->protos.ssh.server_signature)-1, packet->payload_packet_len);
                strncpy(flow->protos.ssh.server_signature, (const char *)packet->payload, len);
                flow->protos.ssh.server_signature[len] = '\0';
                ndpi_ssh_zap_cr(flow->protos.ssh.server_signature, len);
            }

            NDPI_LOG_INFO(ndpi_struct, "found ssh\n");

            ndpi_int_ssh_add_connection(ndpi_struct, flow);
            return;

        }
    }

    NDPI_LOG_DBG(ndpi_struct, "excluding ssh at stage %d\n", flow->l4.tcp.ssh_stage);
    NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_SSH);
}


void init_ssh_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
    ndpi_set_bitmask_protocol_detection("SSH", ndpi_struct, detection_bitmask, *id,
            NDPI_PROTOCOL_SSH,
            ndpi_search_ssh_tcp,
            NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
            SAVE_DETECTION_BITMASK_AS_UNKNOWN,
            ADD_TO_DETECTION_BITMASK);

    *id += 1;
}
