mariadb/sql/sql_crypt.cc
Davi Arnaut 96a3a92c71 Bug#49141: Encode function is significantly slower in 5.1 compared to 5.0
The problem was that the multiple evaluations of a ENCODE or
DECODE function within a single statement caused the random
generator to be reinitialized at each evaluation, even though
the parameters were constants.

The solution is to initialize the random generator only once
if the password (seed) parameter is constant.

This patch borrows code and ideas from Georgi Kodinov's patch.
2009-12-04 13:36:58 -02:00

74 lines
1.9 KiB
C++

/* Copyright (C) 2000-2001, 2003, 2005 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
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 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
Functions to handle the encode() and decode() functions
The strongness of this crypt is large based on how good the random
generator is. It should be ok for short strings, but for communication one
needs something like 'ssh'.
*/
#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation // gcc: Class implementation
#endif
#include "mysql_priv.h"
void SQL_CRYPT::init(ulong *rand_nr)
{
uint i;
randominit(&rand,rand_nr[0],rand_nr[1]);
for (i=0 ; i<=255; i++)
decode_buff[i]= (char) i;
for (i=0 ; i<= 255 ; i++)
{
int idx= (uint) (my_rnd(&rand)*255.0);
char a= decode_buff[idx];
decode_buff[idx]= decode_buff[i];
decode_buff[+i]=a;
}
for (i=0 ; i <= 255 ; i++)
encode_buff[(uchar) decode_buff[i]]=i;
org_rand=rand;
shift=0;
}
void SQL_CRYPT::encode(char *str,uint length)
{
for (uint i=0; i < length; i++)
{
shift^=(uint) (my_rnd(&rand)*255.0);
uint idx= (uint) (uchar) str[0];
*str++ = (char) ((uchar) encode_buff[idx] ^ shift);
shift^= idx;
}
}
void SQL_CRYPT::decode(char *str,uint length)
{
for (uint i=0; i < length; i++)
{
shift^=(uint) (my_rnd(&rand)*255.0);
uint idx= (uint) ((uchar) str[0] ^ shift);
*str = decode_buff[idx];
shift^= (uint) (uchar) *str++;
}
}