/*
 * quic.c
 *
 * Andrea Buscarinu - <andrea.buscarinu@gmail.com>
 * Michele Campus - <michelecampus5@gmail.com>
 * Copyright (C) 2012-15 - ntop.org
 *
 * This module 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.
 *
 * This module 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.
 * If not, see <http://www.gnu.org/licenses/>.
 *
 */


#include "ndpi_api.h"

#define QUIC_NO_V_RES_RSV 0xC3  // 1100 0011

#define QUIC_CID_MASK 0x0C      // 0000 1100
#define QUIC_VER_MASK 0x01      // 0000 0001
#define QUIC_SEQ_MASK 0x30      // 0011 0000

#define CID_LEN_8 0x0C          // 0000 1100
#define CID_LEN_4 0x08          // 0000 1000
#define CID_LEN_1 0x04          // 0000 0100
#define CID_LEN_0 0x00          // 0000 0000

#define SEQ_LEN_6 0x30          // 0011 0000
#define SEQ_LEN_4 0x20          // 0010 0000
#define SEQ_LEN_2 0x10          // 0001 0000
#define SEQ_LEN_1 0x00          // 0000 0000


#ifdef NDPI_PROTOCOL_QUIC
static void ndpi_int_quic_add_connection(struct ndpi_detection_module_struct
                                         *ndpi_struct, struct ndpi_flow_struct *flow)
{
    ndpi_int_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_QUIC, NDPI_REAL_PROTOCOL);
}

static int connect_id(const unsigned char pflags)
{
    u_int cid_len;

        // Check CID length.
        switch (pflags & QUIC_CID_MASK)
        {
           case CID_LEN_8: cid_len = 8; break;
           case CID_LEN_4: cid_len = 4; break;
           case CID_LEN_1: cid_len = 1; break;
           case CID_LEN_0: cid_len = 0; break;
           default:
               return -1;

        }
        // Return offset.
        return cid_len + 1;
}

static int sequence(const unsigned char *payload)
{
    unsigned char conv[6] = {0};
    /* u_int seq_value = -1; */
    int ret = 0;
    int seq_lens;
    int cid_offs;
    int i;

        // Search SEQ bytes length.
        switch (payload[0] & QUIC_SEQ_MASK)
        {
           case SEQ_LEN_6: seq_lens = 6; break;
           case SEQ_LEN_4: seq_lens = 4; break;
           case SEQ_LEN_2: seq_lens = 2; break;
           case SEQ_LEN_1: seq_lens = 1; break;
	}
        // Retrieve SEQ offset.
        cid_offs = connect_id(payload[0]);

        if (cid_offs >= 0 && seq_lens > 0)
        {
	  for (i = 0; i < seq_lens; i++)
	    conv[i] = payload[cid_offs + i];
	  ret = 1;
	}

	// Return SEQ dec value;
        return ret; /* seq_value; */
}

void ndpi_search_quic(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
    struct ndpi_packet_struct *packet = &flow->packet;
    u_int ver_offs;
    
    if(packet->udp != NULL) {

      u_int16_t sport = ntohs(packet->udp->source), dport = ntohs(packet->udp->dest);
      
      NDPI_LOG(NDPI_PROTOCOL_QUIC, ndpi_struct, NDPI_LOG_DEBUG, "calculating quic over udp.\n");
      
      if((packet->payload[0] == 0xC2) && (!((sport == 80) || (dport == 80) || (sport == 443) || (dport == 443))))
      {
	NDPI_LOG(NDPI_PROTOCOL_QUIC, ndpi_struct, NDPI_LOG_DEBUG, "exclude quic.\n");
	NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_QUIC);
      }


      // Settings without version. First check if PUBLIC FLAGS & SEQ bytes are 0x0. SEQ must be 1 at least.
      if (((packet->payload[0] == 0x00) && (packet->payload[1] != 0x00)) || ((packet->payload[0]) & (QUIC_NO_V_RES_RSV == 0)))
      {
	u_int ret = 0;
	ret = sequence(packet->payload);
	if (ret == 0)
	{

	  NDPI_LOG(NDPI_PROTOCOL_QUIC, ndpi_struct, NDPI_LOG_DEBUG, "exclude quic.\n");
	  NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_QUIC);
	}

	NDPI_LOG(NDPI_PROTOCOL_QUIC, ndpi_struct, NDPI_LOG_DEBUG, "found quic.\n");
	ndpi_int_quic_add_connection(ndpi_struct, flow);
      }

      // Check if version, than the CID length.
      else if (packet->payload[0] & QUIC_VER_MASK)
      {
	// Skip CID length.
	ver_offs = connect_id(packet->payload[0]);
	
	if(ver_offs != -1)
	{
	  unsigned char vers[] = {packet->payload[ver_offs], packet->payload[ver_offs + 1],
				  packet->payload[ver_offs + 2], packet->payload[ver_offs + 3]};
	  
	  // Version Match.
	  if ((vers[0] == 'Q' && vers[1] == '0') &&
	      ((vers[2] == '2' && (vers[3] == '5' || vers[3] == '4' || vers[3] == '3' || vers[3] == '2' ||
				   vers[3] == '1' || vers[3] == '0')) ||
	       (vers[2] == '1' && (vers[3] == '9' || vers[3] == '8' || vers[3] == '7' || vers[3] == '6' ||
				    vers[3] == '5' || vers[3] == '4' || vers[3] == '3' || vers[3] == '2' ||
				    vers[3] == '1' || vers[3] == '0')) ||
		(vers[2] == '0' && vers[3] == '9')))
	      
	  {
	    NDPI_LOG(NDPI_PROTOCOL_QUIC, ndpi_struct, NDPI_LOG_DEBUG, "found quic.\n");
	    ndpi_int_quic_add_connection(ndpi_struct, flow);
	  }
	}
      } else
      {
	NDPI_LOG(NDPI_PROTOCOL_QUIC, ndpi_struct, NDPI_LOG_DEBUG, "exclude quic.\n");
	NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_QUIC);
      }
    }
}
#endif