/*
 * Copyright 2013-2019 Software Radio Systems Limited
 *
 * This file is part of srsLTE.
 *
 * srsLTE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * srsLTE 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 Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

#ifndef SRSLTE_PCAP_H
#define SRSLTE_PCAP_H

#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <sys/time.h>

#define MAC_LTE_DLT 147
#define NAS_LTE_DLT 148
#define UDP_DLT 149 // UDP needs to be selected as protocol
#define S1AP_LTE_DLT 150

/* This structure gets written to the start of the file */
typedef struct pcap_hdr_s {
  unsigned int   magic_number;  /* magic number */
  unsigned short version_major; /* major version number */
  unsigned short version_minor; /* minor version number */
  unsigned int   thiszone;      /* GMT to local correction */
  unsigned int   sigfigs;       /* accuracy of timestamps */
  unsigned int   snaplen;       /* max length of captured packets, in octets */
  unsigned int   network;       /* data link type */
} pcap_hdr_t;

/* This structure precedes each packet */
typedef struct pcaprec_hdr_s {
  unsigned int ts_sec;   /* timestamp seconds */
  unsigned int ts_usec;  /* timestamp microseconds */
  unsigned int incl_len; /* number of octets of packet saved in file */
  unsigned int orig_len; /* actual length of packet */
} pcaprec_hdr_t;

/* radioType */
#define FDD_RADIO 1
#define TDD_RADIO 2

/* Direction */
#define DIRECTION_UPLINK 0
#define DIRECTION_DOWNLINK 1

/* rntiType */
#define NO_RNTI 0 /* Used for BCH-BCH */
#define P_RNTI 1
#define RA_RNTI 2
#define C_RNTI 3
#define SI_RNTI 4
#define SPS_RNTI 5
#define M_RNTI 6

#define MAC_LTE_START_STRING "mac-lte"
#define MAC_LTE_PAYLOAD_TAG 0x01
#define MAC_LTE_RNTI_TAG 0x02
#define MAC_LTE_UEID_TAG 0x03
#define MAC_LTE_FRAME_SUBFRAME_TAG 0x04
#define MAC_LTE_PREDFINED_DATA_TAG 0x05
#define MAC_LTE_RETX_TAG 0x06
#define MAC_LTE_CRC_STATUS_TAG 0x07
#define MAC_LTE_NB_MODE_TAG 0x0F

/* Context information for every MAC PDU that will be logged */
typedef struct MAC_Context_Info_t {
  unsigned short radioType;
  unsigned char  direction;
  unsigned char  rntiType;
  unsigned short rnti;
  unsigned short ueid;
  unsigned char  isRetx;
  unsigned char  crcStatusOK;

  unsigned short sysFrameNumber;
  unsigned short subFrameNumber;

  unsigned char nbiotMode;
} MAC_Context_Info_t;

/* Context information for every NAS PDU that will be logged */
typedef struct NAS_Context_Info_s {
  // No Context yet
} NAS_Context_Info_t;

#define MAC_NR_START_STRING "mac-nr"
#define MAC_NR_PHR_TYPE2_OTHERCELL_TAG 0x05
#define MAC_NR_HARQID 0x06

/* Context information for every MAC NR PDU that will be logged */
typedef struct {
  uint8_t  radioType;
  uint8_t  direction;
  uint8_t  rntiType;
  uint16_t rnti;
  uint16_t ueid;
  uint8_t  harqid;

  uint8_t phr_type2_othercell;

  uint16_t system_frame_number;
  uint8_t  sub_frame_number;
  uint16_t length;
} mac_nr_context_info_t;

/* RLC-LTE disector */

/* rlcMode */
#define RLC_TM_MODE 1
#define RLC_UM_MODE 2
#define RLC_AM_MODE 4
#define RLC_PREDEF 8

/* priority ? */

/* channelType */
#define CHANNEL_TYPE_CCCH 1
#define CHANNEL_TYPE_BCCH_BCH 2
#define CHANNEL_TYPE_PCCH 3
#define CHANNEL_TYPE_SRB 4
#define CHANNEL_TYPE_DRB 5
#define CHANNEL_TYPE_BCCH_DL_SCH 6
#define CHANNEL_TYPE_MCCH 7
#define CHANNEL_TYPE_MTCH 8

/* sequenceNumberLength */
#define UM_SN_LENGTH_5_BITS 5
#define UM_SN_LENGTH_10_BITS 10
#define AM_SN_LENGTH_10_BITS 10
#define AM_SN_LENGTH_16_BITS 16

/* Narrow band mode */
typedef enum { rlc_no_nb_mode = 0, rlc_nb_mode = 1 } rlc_lte_nb_mode;

/* Context information for every RLC PDU that will be logged */
typedef struct {
  unsigned char   rlcMode;
  unsigned char   direction;
  unsigned char   priority;
  unsigned char   sequenceNumberLength;
  unsigned short  ueid;
  unsigned short  channelType;
  unsigned short  channelId; /* for SRB: 1=SRB1, 2=SRB2, 3=SRB1bis; for DRB: DRB ID */
  unsigned short  pduLength;
  bool            extendedLiField;
  rlc_lte_nb_mode nbMode;
} RLC_Context_Info_t;

// See Wireshark's packet-rlc-lte.h for details
#define RLC_LTE_START_STRING "rlc-lte"
#define RLC_LTE_SN_LENGTH_TAG 0x02
#define RLC_LTE_DIRECTION_TAG 0x03
#define RLC_LTE_PRIORITY_TAG 0x04
#define RLC_LTE_UEID_TAG 0x05
#define RLC_LTE_CHANNEL_TYPE_TAG 0x06
#define RLC_LTE_CHANNEL_ID_TAG 0x07
#define RLC_LTE_EXT_LI_FIELD_TAG 0x08
#define RLC_LTE_NB_MODE_TAG 0x09
#define RLC_LTE_PAYLOAD_TAG 0x01

/* Context information for every S1AP PDU that will be logged */
typedef struct S1AP_Context_Info_s {
  // No Context yet
} S1AP_Context_Info_t;

/**************************************************************************
 * API functions for opening/closing LTE PCAP files                       *
 **************************************************************************/

/* Open the file and write file header */
inline FILE* LTE_PCAP_Open(uint32_t DLT, const char* fileName)
{
  pcap_hdr_t file_header = {
      0xa1b2c3d4, /* magic number */
      2,
      4,     /* version number is 2.4 */
      0,     /* timezone */
      0,     /* sigfigs - apparently all tools do this */
      65535, /* snaplen - this should be long enough */
      DLT    /* Data Link Type (DLT).  Set as unused value 147 for now */
  };

  FILE* fd = fopen(fileName, "w");
  if (fd == NULL) {
    printf("Failed to open file \"%s\" for writing\n", fileName);
    return NULL;
  }

  /* Write the file header */
  fwrite(&file_header, sizeof(pcap_hdr_t), 1, fd);

  return fd;
}

/* Close the PCAP file */
inline void LTE_PCAP_Close(FILE* fd)
{
  if (fd)
    fclose(fd);
}

/**************************************************************************
 * API functions for writing MAC-LTE PCAP files                           *
 **************************************************************************/

/* Write an individual PDU (PCAP packet header + mac-context + mac-pdu) */
inline int LTE_PCAP_MAC_WritePDU(FILE* fd, MAC_Context_Info_t* context, const unsigned char* PDU, unsigned int length)
{
  pcaprec_hdr_t packet_header;
  char          context_header[256];
  int           offset = 0;
  uint16_t      tmp16;

  /* Can't write if file wasn't successfully opened */
  if (fd == NULL) {
    printf("Error: Can't write to empty file handle\n");
    return 0;
  }

  /*****************************************************************/
  /* Context information (same as written by UDP heuristic clients */
  context_header[offset++] = context->radioType;
  context_header[offset++] = context->direction;
  context_header[offset++] = context->rntiType;

  /* RNTI */
  context_header[offset++] = MAC_LTE_RNTI_TAG;
  tmp16                    = htons(context->rnti);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  /* UEId */
  context_header[offset++] = MAC_LTE_UEID_TAG;
  tmp16                    = htons(context->ueid);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  /* Subframe Number and System Frame Number */
  /* SFN is stored in 12 MSB and SF in 4 LSB */
  context_header[offset++] = MAC_LTE_FRAME_SUBFRAME_TAG;
  tmp16                    = (context->sysFrameNumber << 4) | context->subFrameNumber;
  tmp16                    = htons(tmp16);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  /* CRC Status */
  context_header[offset++] = MAC_LTE_CRC_STATUS_TAG;
  context_header[offset++] = context->crcStatusOK;

  /* NB-IoT mode tag */
  context_header[offset++] = MAC_LTE_NB_MODE_TAG;
  context_header[offset++] = context->nbiotMode;

  /* Data tag immediately preceding PDU */
  context_header[offset++] = MAC_LTE_PAYLOAD_TAG;

  /****************************************************************/
  /* PCAP Header                                                  */
  struct timeval t;
  gettimeofday(&t, NULL);
  packet_header.ts_sec   = t.tv_sec;
  packet_header.ts_usec  = t.tv_usec;
  packet_header.incl_len = offset + length;
  packet_header.orig_len = offset + length;

  /***************************************************************/
  /* Now write everything to the file                            */
  fwrite(&packet_header, sizeof(pcaprec_hdr_t), 1, fd);
  fwrite(context_header, 1, offset, fd);
  fwrite(PDU, 1, length, fd);

  return 1;
}

/**************************************************************************
 * API functions for writing NAS-EPS PCAP files                           *
 **************************************************************************/

/* Write an individual PDU (PCAP packet header + nas-context + nas-pdu) */
inline int LTE_PCAP_NAS_WritePDU(FILE* fd, NAS_Context_Info_t* context, const unsigned char* PDU, unsigned int length)
{
  pcaprec_hdr_t packet_header;

  /* Can't write if file wasn't successfully opened */
  if (fd == NULL) {
    printf("Error: Can't write to empty file handle\n");
    return 0;
  }

  /****************************************************************/
  /* PCAP Header                                                  */
  struct timeval t;
  gettimeofday(&t, NULL);
  packet_header.ts_sec   = t.tv_sec;
  packet_header.ts_usec  = t.tv_usec;
  packet_header.incl_len = length;
  packet_header.orig_len = length;

  /***************************************************************/
  /* Now write everything to the file                            */
  fwrite(&packet_header, sizeof(pcaprec_hdr_t), 1, fd);
  fwrite(PDU, 1, length, fd);

  return 1;
}

/**************************************************************************
 * API functions for writing RLC-LTE PCAP files                           *
 **************************************************************************/

/* Write an individual RLC PDU (PCAP packet header + UDP header + rlc-context + rlc-pdu) */
inline int LTE_PCAP_RLC_WritePDU(FILE* fd, RLC_Context_Info_t* context, const unsigned char* PDU, unsigned int length)
{
  pcaprec_hdr_t packet_header;
  char          context_header[256];
  int           offset = 0;
  uint16_t      tmp16;

  /* Can't write if file wasn't successfully opened */
  if (fd == NULL) {
    printf("Error: Can't write to empty file handle\n");
    return 0;
  }

  /*****************************************************************/

  // Add dummy UDP header, start with src and dest port
  context_header[offset++] = 0xde;
  context_header[offset++] = 0xad;
  context_header[offset++] = 0xbe;
  context_header[offset++] = 0xef;
  // length
  tmp16 = length + 12;
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;
  // dummy CRC
  context_header[offset++] = 0xde;
  context_header[offset++] = 0xad;

  // Start magic string
  memcpy(&context_header[offset], RLC_LTE_START_STRING, strlen(RLC_LTE_START_STRING));
  offset += strlen(RLC_LTE_START_STRING);

  // Fixed field RLC mode
  context_header[offset++] = context->rlcMode;

  // Conditional fields
  if (context->rlcMode == RLC_UM_MODE) {
    context_header[offset++] = RLC_LTE_SN_LENGTH_TAG;
    context_header[offset++] = context->sequenceNumberLength;
  }

  // Optional fields
  context_header[offset++] = RLC_LTE_DIRECTION_TAG;
  context_header[offset++] = context->direction;

  context_header[offset++] = RLC_LTE_PRIORITY_TAG;
  context_header[offset++] = context->priority;

  context_header[offset++] = RLC_LTE_UEID_TAG;
  tmp16                    = htons(context->ueid);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  context_header[offset++] = RLC_LTE_CHANNEL_TYPE_TAG;
  tmp16                    = htons(context->channelType);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  context_header[offset++] = RLC_LTE_CHANNEL_ID_TAG;
  tmp16                    = htons(context->channelId);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  // Now the actual PDU
  context_header[offset++] = RLC_LTE_PAYLOAD_TAG;

  // PCAP header
  struct timeval t;
  gettimeofday(&t, NULL);
  packet_header.ts_sec   = t.tv_sec;
  packet_header.ts_usec  = t.tv_usec;
  packet_header.incl_len = offset + length;
  packet_header.orig_len = offset + length;

  // Write everything to file
  fwrite(&packet_header, sizeof(pcaprec_hdr_t), 1, fd);
  fwrite(context_header, 1, offset, fd);
  fwrite(PDU, 1, length, fd);

  return 1;
}

/**************************************************************************
 * API functions for writing S1AP PCAP files                           *
 **************************************************************************/

/* Write an individual PDU (PCAP packet header + s1ap-context + s1ap-pdu) */
inline int LTE_PCAP_S1AP_WritePDU(FILE* fd, S1AP_Context_Info_t* context, const unsigned char* PDU, unsigned int length)
{
  pcaprec_hdr_t packet_header;

  /* Can't write if file wasn't successfully opened */
  if (fd == NULL) {
    printf("Error: Can't write to empty file handle\n");
    return 0;
  }

  /****************************************************************/
  /* PCAP Header                                                  */
  struct timeval t;
  gettimeofday(&t, NULL);
  packet_header.ts_sec   = t.tv_sec;
  packet_header.ts_usec  = t.tv_usec;
  packet_header.incl_len = length;
  packet_header.orig_len = length;

  /***************************************************************/
  /* Now write everything to the file                            */
  fwrite(&packet_header, sizeof(pcaprec_hdr_t), 1, fd);
  fwrite(PDU, 1, length, fd);

  return 1;
}

/**************************************************************************
 * API functions for writing MAC-NR PCAP files                           *
 **************************************************************************/

/* Write an individual NR MAC PDU (PCAP packet header + UDP header + nr-mac-context + mac-pdu) */
inline int NR_PCAP_MAC_WritePDU(FILE* fd, mac_nr_context_info_t* context, const unsigned char* PDU, unsigned int length)
{
  char context_header[256] = {};
  int  offset              = 0;

  /* Can't write if file wasn't successfully opened */
  if (fd == NULL) {
    printf("Error: Can't write to empty file handle\n");
    return 0;
  }

  // Add dummy UDP header, start with src and dest port
  context_header[offset++] = 0xde;
  context_header[offset++] = 0xad;
  context_header[offset++] = 0xbe;
  context_header[offset++] = 0xef;
  // length
  uint16_t tmp16 = htons(length + 31);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;
  // dummy CRC
  context_header[offset++] = 0xde;
  context_header[offset++] = 0xad;

  // Start magic string
  memcpy(&context_header[offset], MAC_NR_START_STRING, strlen(MAC_NR_START_STRING));
  offset += strlen(MAC_NR_START_STRING);

  /*****************************************************************/
  /* Context information (same as written by UDP heuristic clients */
  context_header[offset++] = context->radioType;
  context_header[offset++] = context->direction;
  context_header[offset++] = context->rntiType;

  /* RNTI */
  context_header[offset++] = MAC_LTE_RNTI_TAG;
  tmp16                    = htons(context->rnti);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  /* UEId */
  context_header[offset++] = MAC_LTE_UEID_TAG;
  tmp16                    = htons(context->ueid);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  /* HARQID */
  context_header[offset++] = MAC_NR_HARQID;
  context_header[offset++] = context->harqid;

  /* PHR Type2 other cell */
  context_header[offset++] = MAC_NR_PHR_TYPE2_OTHERCELL_TAG;
  context_header[offset++] = context->phr_type2_othercell;

  /* Subframe Number and System Frame Number */
  /* SFN is stored in 12 MSB and SF in 4 LSB */
  context_header[offset++] = MAC_LTE_FRAME_SUBFRAME_TAG;
  tmp16                    = (context->system_frame_number << 4) | context->sub_frame_number;
  tmp16                    = htons(tmp16);
  memcpy(context_header + offset, &tmp16, 2);
  offset += 2;

  /* Data tag immediately preceding PDU */
  context_header[offset++] = MAC_LTE_PAYLOAD_TAG;

  /****************************************************************/
  /* PCAP Header                                                  */
  struct timeval t;
  gettimeofday(&t, NULL);
  pcaprec_hdr_t packet_header;
  packet_header.ts_sec   = t.tv_sec;
  packet_header.ts_usec  = t.tv_usec;
  packet_header.incl_len = offset + length;
  packet_header.orig_len = offset + length;

  /***************************************************************/
  /* Now write everything to the file                            */
  fwrite(&packet_header, sizeof(pcaprec_hdr_t), 1, fd);
  fwrite(context_header, 1, offset, fd);
  fwrite(PDU, 1, length, fd);

  return 1;
}

#endif // SRSLTE_PCAP_H