///////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2000-2019 Ericsson Telecom AB
//
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v2.0
// which accompanies this distribution, and is available at
// https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.html
///////////////////////////////////////////////////////////////////////////////
//
//  File:               SCTP_EncDec.cc
//  Description:        Encoder/decoder for SCTP messages
//  Rev:                R1B
//  Prodnr:             CNL 113 830
//  Reference:          RFC4690

#include "SCTP_Types.hh"
#include <stdint.h>

static const uint32_t crc_table[256] =
   {
   0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,
   0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,
   0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,
   0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,
   0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,
   0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,
   0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,
   0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,
   0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
   0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,
   0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,
   0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,
   0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,
   0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,
   0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,
   0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,
   0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,
   0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
   0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,
   0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,
   0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,
   0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,
   0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,
   0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,
   0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,
   0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,
   0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
   0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,
   0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,
   0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,
   0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,
   0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,
   0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,
   0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,
   0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,
   0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
   0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,
   0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,
   0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,
   0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,
   0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,
   0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,
   0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,
   0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,
   0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
   0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,
   0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,
   0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,
   0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,
   0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,
   0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,
   0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,
   0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,
   0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
   0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,
   0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,
   0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,
   0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,
   0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,
   0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,
   0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,
   0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,
   0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
   0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
   };

void sctp_gen_crc(const unsigned char *buff, size_t len, unsigned char* res){
  uint32_t crc32 = ~0L;

  for(size_t i = 0; i < len; i++){
      crc32=(crc32>>8)^crc_table[(crc32^buff[i])&0xff];
  }

  crc32 = ~crc32;

  res[3]=(crc32>> 24) & 0xff;
  res[2]=(crc32>> 16) & 0xff;
  res[1]=(crc32>> 8) & 0xff;
  res[0]=crc32 & 0xff;
  
}

namespace SCTP__Types {

OCTETSTRING f__SCTP__enc(const SCTP__Packet& pl__pdu)
{
  if (TTCN_Logger::log_this_event(TTCN_Logger::DEBUG_ENCDEC)) {
    TTCN_Logger::begin_event(TTCN_Logger::DEBUG_ENCDEC);
    TTCN_Logger::log_event_str("f_SCTP_enc(): Encoding @SCTP_Types.SCTP_Packet: ");
    pl__pdu.log();
    TTCN_Logger::end_event();
  }
  TTCN_EncDec::set_error_behavior(TTCN_EncDec::ET_ALL, TTCN_EncDec::EB_DEFAULT);
  TTCN_Buffer ttcn_buffer;
  pl__pdu.encode(SCTP__Packet_descr_, ttcn_buffer, TTCN_EncDec::CT_RAW);

  size_t len=ttcn_buffer.get_len();
  size_t p_len=0;
  unsigned char* ptr=NULL;
  ttcn_buffer.get_end(ptr,p_len);
  
  ptr= ptr - len;
  
  ptr[8]=0;
  ptr[9]=0;
  ptr[10]=0;
  ptr[11]=0;
  
  sctp_gen_crc(ptr,len,ptr+8);


  OCTETSTRING ret_val;
  ttcn_buffer.get_string(ret_val);
  if (TTCN_Logger::log_this_event(TTCN_Logger::DEBUG_ENCDEC)) {
    TTCN_Logger::begin_event(TTCN_Logger::DEBUG_ENCDEC);
    TTCN_Logger::log_event_str("f_SCTP_enc(): Stream after encoding: ");
    ret_val.log();
    TTCN_Logger::end_event();
  }
  return ret_val;
}

INTEGER f__SCTP__dec(const OCTETSTRING& pl__stream, SCTP__Packet& pl__pdu)
{
  if (TTCN_Logger::log_this_event(TTCN_Logger::DEBUG_ENCDEC)) {
    TTCN_Logger::begin_event(TTCN_Logger::DEBUG_ENCDEC);
    TTCN_Logger::log_event_str("f_SCTP_dec(): Stream before decoding: ");
    pl__stream.log();
    TTCN_Logger::end_event();
  }

  TTCN_EncDec::set_error_behavior(TTCN_EncDec::ET_ALL, TTCN_EncDec::EB_WARNING);
  TTCN_EncDec::clear_error();
  TTCN_Buffer ttcn_buffer(pl__stream);

  size_t len=ttcn_buffer.get_len();
  size_t p_len=0;
  unsigned char* ptr=NULL;
  ttcn_buffer.get_end(ptr,p_len);
  
  ptr= ptr - len;
  unsigned char crc_orig[4];
  crc_orig[0]=ptr[8];
  crc_orig[1]=ptr[9];
  crc_orig[2]=ptr[10];
  crc_orig[3]=ptr[11];
  
  ptr[8]=0;
  ptr[9]=0;
  ptr[10]=0;
  ptr[11]=0;
  unsigned char crc[4];
  sctp_gen_crc(ptr,len,crc);
  
  if((crc_orig[0]!= crc[0]) || (crc_orig[1]!= crc[1]) || (crc_orig[2]!= crc[2]) || (crc_orig[3]!= crc[3])){
    return 1;
  }
  ptr[8]=crc[0];
  ptr[9]=crc[1];
  ptr[10]=crc[2];
  ptr[11]=crc[3];
  
  pl__pdu.decode(SCTP__Packet_descr_, ttcn_buffer, TTCN_EncDec::CT_RAW);

  if (TTCN_Logger::log_this_event(TTCN_Logger::DEBUG_ENCDEC)) {
    TTCN_Logger::begin_event(TTCN_Logger::DEBUG_ENCDEC);
    TTCN_Logger::log_event_str("f_SCTP_dec(): Decoded @SCTP_Types.SCTP_Packet: ");
    pl__pdu.log();
    TTCN_Logger::end_event();
  }
  if (TTCN_EncDec::get_last_error_type() == TTCN_EncDec::ET_NONE) {
    return 0;
  } else {
    return 1;
  }
}

}