libbinlogevents/src/binlog_event.cpp

/* Copyright (c) 2011, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program 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 General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "binary_log_types.h"

#include "statement_events.h"

#include <algorithm>
#include <stdint.h>

const unsigned char checksum_version_split[3]= {5, 6, 1};
const unsigned long checksum_version_product=
  (checksum_version_split[0] * 256 + checksum_version_split[1]) * 256 +
  checksum_version_split[2];


namespace binary_log_debug
{
  bool debug_query_mts_corrupt_db_names= false;
  bool debug_checksum_test= false;
  bool debug_simulate_invalid_address= false;
  bool debug_pretend_version_50034_in_binlog= false;
}

namespace binary_log
{
/**
   The method returns the checksum algorithm used to checksum the binary log.
   For MySQL server versions < 5.6, the algorithm is undefined. For the higher
   versions, the type is decoded from the FORMAT_DESCRIPTION_EVENT.

   @param buf buffer holding serialized FD event
   @param len netto (possible checksum is stripped off) length of the event buf

   @return  the version-safe checksum alg descriptor where zero
            designates no checksum, 255 - the orginator is
            checksum-unaware (effectively no checksum) and the actuall
            [1-254] range alg descriptor.
*/
enum_binlog_checksum_alg
Log_event_footer::get_checksum_alg(const char* buf, unsigned long len)
{
  enum_binlog_checksum_alg ret;
  char version[ST_SERVER_VER_LEN];
  unsigned char version_split[3];
  BAPI_ASSERT(buf[EVENT_TYPE_OFFSET] == FORMAT_DESCRIPTION_EVENT);
  memcpy(version, buf +
         buf[LOG_EVENT_MINIMAL_HEADER_LEN + ST_COMMON_HEADER_LEN_OFFSET]
         + ST_SERVER_VER_OFFSET, ST_SERVER_VER_LEN);
  version[ST_SERVER_VER_LEN - 1]= 0;

  do_server_version_split(version, version_split);
  if (version_product(version_split) < checksum_version_product)
    ret=  BINLOG_CHECKSUM_ALG_UNDEF;
  else
    ret= static_cast<enum_binlog_checksum_alg>(*(buf + len -
                                                 BINLOG_CHECKSUM_LEN -
                                                 BINLOG_CHECKSUM_ALG_DESC_LEN));
  BAPI_ASSERT(ret == BINLOG_CHECKSUM_ALG_OFF ||
              ret == BINLOG_CHECKSUM_ALG_UNDEF ||
              ret == BINLOG_CHECKSUM_ALG_CRC32);
  return ret;
}

/**
  Log_event_header constructor

  @param buf                  the buffer containing the complete information
                              including the event and the header data

  @param description_event    first constructor of Format_description_event,
                              used to extract the binlog_version
*/
Log_event_header::
Log_event_header(const char* buf, uint16_t binlog_version)
: data_written(0), log_pos(0)
{
  uint32_t tmp_sec;
  memcpy(&tmp_sec, buf, sizeof(tmp_sec));
  when.tv_sec= le32toh(tmp_sec);
  when.tv_usec= 0;
  type_code= static_cast<Log_event_type>(buf[EVENT_TYPE_OFFSET]);
  memcpy(&unmasked_server_id,
         buf + SERVER_ID_OFFSET, sizeof(unmasked_server_id));

  unmasked_server_id= le32toh(unmasked_server_id);

  /**
    @verbatim
    The first 13 bytes in the header is as follows:
      +============================================+
      | member_variable               offset : len |
      +============================================+
      | when.tv_sec                        0 : 4   |
      +--------------------------------------------+
      | type_code       EVENT_TYPE_OFFSET(4) : 1   |
      +--------------------------------------------+
      | server_id       SERVER_ID_OFFSET(5)  : 4   |
      +--------------------------------------------+
      | data_written    EVENT_LEN_OFFSET(9)  : 4   |
      +============================================+
    @endverbatim
   */
  memcpy(&data_written, buf + EVENT_LEN_OFFSET, 4);
  data_written= le64toh(data_written);

  memcpy(&log_pos, buf + LOG_POS_OFFSET, 4);
  log_pos= le64toh(log_pos);

  switch (binlog_version)
  {
  case 1:
    log_pos= 0;
    flags= 0;
    break;

  case 3:
    /*
      If the log is 4.0 (so here it can only be a 4.0 relay log read by
      the SQL thread or a 4.0 master binlog read by the I/O thread),
      log_pos is the beginning of the event: we transform it into the end
      of the event, which is more useful.
      But how do you know that the log is 4.0: you know it if
      description_event is version 3 *and* you are not reading a
      Format_desc (remember that mysqlbinlog starts by assuming that 5.0
      logs are in 4.0 format, until it finds a Format_desc).
    */
    if (buf[EVENT_TYPE_OFFSET] < FORMAT_DESCRIPTION_EVENT && log_pos)
    {
      /*
        If log_pos=0, don't change it. log_pos==0 is a marker to mean
        "don't change rli->group_master_log_pos" (see
        inc_group_relay_log_pos()). As it is unreal log_pos, adding the
        event len's is not correct. For example, a fake Rotate event should
        not have its log_pos (which is 0) changed or it will modify
        Exec_master_log_pos in SHOW SLAVE STATUS, displaying a wrong
        value of (a non-zero offset which does not exist in the master's
        binlog, so which will cause problems if the user uses this value
        in CHANGE MASTER).
      */
      log_pos+= data_written; /* purecov: inspected */
    }

  /* 4.0 or newer */
  /**
    @verbatim
    Additional header fields include:
      +=============================================+
      | member_variable               offset : len  |
      +=============================================+
      | log_pos           LOG_POS_OFFSET(13) : 4    |
      +---------------------------------------------+
      | flags               FLAGS_OFFSET(17) : 1    |
      +---------------------------------------------+
      | extra_headers                     19 : x-19 |
      +=============================================+
     extra_headers are not used in the current version.
    @endverbatim
   */
    // Fall through.
  default:
    memcpy(&flags, buf + FLAGS_OFFSET, sizeof(flags));
    flags= le16toh(flags);

     if ((buf[EVENT_TYPE_OFFSET] == FORMAT_DESCRIPTION_EVENT) ||
         (buf[EVENT_TYPE_OFFSET] == ROTATE_EVENT))
     {
       /*
         These events always have a header which stops here (i.e. their
         header is FROZEN).
       */
       /*
         Initialization to zero of all other Log_event members as they're
         not specified. Currently there are no such members; in the future
         there will be an event UID (but Format_description and Rotate
         don't need this UID, as they are not propagated through
         --log-slave-updates (remember the UID is used to not play a query
         twice when you have two masters which are slaves of a 3rd master).
         Then we are done with decoding the header.
      */
      break;
    }
  /* otherwise, go on with reading the header from buf (nothing now) */
  } //end switch (binlog_version)
  BAPI_ASSERT(type_code < ENUM_END_EVENT || flags & LOG_EVENT_IGNORABLE_F);
}


/**
  Tests the checksum algorithm used for the binary log, and asserts in case
  if the checksum algorithm is invalid.

  @param   event_buf       point to the buffer containing serialized event
  @param   event_len       length of the event accounting possible
                           checksum alg
  @param   alg             checksum algorithm used for the binary log

  @retval  true            if test fails
  @retval  false           as success
*/
bool Log_event_footer::event_checksum_test(unsigned char *event_buf,
                                           unsigned long event_len,
                                           enum_binlog_checksum_alg alg)
{
  bool res= false;
  unsigned short flags= 0; // to store in FD's buffer flags orig value

  if (alg != BINLOG_CHECKSUM_ALG_OFF && alg != BINLOG_CHECKSUM_ALG_UNDEF)
  {
    uint32_t incoming;
    uint32_t computed;

    if (event_buf[EVENT_TYPE_OFFSET] == FORMAT_DESCRIPTION_EVENT)
    {
    #ifndef NDEBUG
      unsigned char fd_alg= event_buf[event_len - BINLOG_CHECKSUM_LEN -
                                      BINLOG_CHECKSUM_ALG_DESC_LEN];
    #endif
      /*
        FD event is checksummed and therefore verified w/o
        the binlog-in-use flag.
      */
      memcpy(&flags, event_buf + FLAGS_OFFSET, sizeof(flags));
      flags= le16toh(flags);
      if (flags & LOG_EVENT_BINLOG_IN_USE_F)
        event_buf[FLAGS_OFFSET] &= ~LOG_EVENT_BINLOG_IN_USE_F;
      /*
         The only algorithm currently is CRC32. Zero indicates
         the binlog file is checksum-free *except* the FD-event.
      */
    #ifndef NDEBUG
      BAPI_ASSERT(fd_alg == BINLOG_CHECKSUM_ALG_CRC32 || fd_alg == 0);
    #endif
      BAPI_ASSERT(alg == BINLOG_CHECKSUM_ALG_CRC32);
      /*
        Complile time guard to watch over  the max number of alg
      */
      do_compile_time_assert(BINLOG_CHECKSUM_ALG_ENUM_END <= 0x80);
    }
    memcpy(&incoming,
           event_buf + event_len - BINLOG_CHECKSUM_LEN, sizeof(incoming));
    incoming= le32toh(incoming);

    computed= checksum_crc32(0L, NULL, 0);
    /* checksum the event content but not the checksum part itself */
    computed= binary_log::checksum_crc32(computed,
                                         (const unsigned char*) event_buf,
                                         event_len - BINLOG_CHECKSUM_LEN);

    if (flags != 0)
    {
      /* restoring the orig value of flags of FD */
      BAPI_ASSERT(event_buf[EVENT_TYPE_OFFSET] == FORMAT_DESCRIPTION_EVENT);
      event_buf[FLAGS_OFFSET]= static_cast<unsigned char>(flags);
    }

    res= !(computed == incoming);
  }
#ifndef NDEBUG
  if (binary_log_debug::debug_checksum_test)
    return true;
#endif
  return res;
}


/**
  This ctor will create a new object of Log_event_header, and initialize
  the variable m_header, which in turn will be used to initialize Log_event's
  member common_header.
  It will also advance the buffer after decoding the header(it is done through
  the constructor of Log_event_header) and
  will be pointing to the start of event data
*/
Binary_log_event::Binary_log_event(const char **buf, uint16_t binlog_version,
                                   const char *server_version)
: m_header(*buf, binlog_version)
{
  m_footer= Log_event_footer();
  //buf is advanced in Binary_log_event constructor to point to beginning of
  //post-header
  (*buf)+= LOG_EVENT_HEADER_LEN;
}

/*
  The destructor is pure virtual to prevent instantiation of the class.
*/
Binary_log_event::~Binary_log_event()
{
}

  /**
    This event type should never occur. It is never written to a binary log.
    If an event is read from a binary log that cannot be recognized as something
    else, it is treated as Unknown_event.

    @param buf                Contains the serialized event.
    @param description_event  An FDE event, used to get the following information
                              -binlog_version
                              -server_version
                              -post_header_len
                              -common_header_len
                              The content of this object
                              depends on the binlog-version currently in use.
  */
Unknown_event::Unknown_event(const char* buf,
                const Format_description_event *description_event)
  : Binary_log_event(&buf,
                     description_event->binlog_version,
                     description_event->server_version)
  {
  }
#ifndef HAVE_MYSYS
void Binary_log_event::print_event_info(std::ostream& info) {}
void Binary_log_event::print_long_info(std::ostream& info) {}
/**
  This method is used by the binlog_browser to print short and long
  information about the event. Since the body of Stop_event is empty
  the relevant information contains only the timestamp.
  Please note this is different from the print_event_info methods
  used by mysqlbinlog.cc.

  @param std output stream to which the event data is appended.
*/
void Stop_event::print_long_info(std::ostream& info)
{
  info << "Timestamp: " << header()->when.tv_sec;
  this->print_event_info(info);
}

void Unknown_event::print_event_info(std::ostream& info)
{
  info << "Unhandled event";
}

void Unknown_event::print_long_info(std::ostream& info)
{
  info << "Timestamp: " << header()->when.tv_sec;
  this->print_event_info(info);
}

#endif
} // end namespace binary_log