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/*
Unix SMB/Netbios implementation.
Version 1.9.
Functions to create reasonable random numbers for crypto use.
Copyright (C) Jeremy Allison 1998
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; either version 2 of the License, or
(at your option) any later version.
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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
extern int DEBUGLEVEL;
/**************************************************************
Try and get a good random number seed. Try a number of
different factors. Firstly, try /dev/random and try and
read from this. If this fails iterate through /tmp and
XOR all the file timestamps. If this fails then just use
a combination of pid and time of day (yes I know this
sucks :-). Finally md4 the result.
**************************************************************/
static uint32 do_reseed(void)
{
static int counter = 0;
unsigned char md4_outbuf[16];
unsigned char md4_inbuf[40];
BOOL got_random = False;
uint32 v1, v2, ret;
int fd;
struct timeval tval;
memset(md4_inbuf, '\0', sizeof(md4_inbuf));
fd = open( "/dev/random", O_RDONLY);
if(fd >= 0) {
/*
* We can use /dev/random !
*/
if(read(fd, md4_inbuf, 40) == 40) {
got_random = True;
DEBUG(10,("do_reseed: got 40 bytes from /dev/random.\n"));
}
close(fd);
}
if(!got_random) {
/*
* /dev/random failed - try /tmp/ for timestamps.
*/
void *dp = sys_opendir("/tmp");
if(dp != NULL) {
char *p;
while ((p = readdirname(dp))) {
struct stat st;
if(sys_stat(p,&st) != 0)
SIVAL(md4_inbuf, ((counter%sizeof(md4_inbuf))/4),
IVAL(md4_inbuf,((counter%sizeof(md4_inbuf))/4)) ^ st.st_atime);
counter++;
DEBUG(10,("do_reseed: value from file %s.\n", p));
}
}
closedir(dp);
}
/*
* Finally add the counter, time of day, and pid.
*/
GetTimeOfDay(&tval);
v1 = (counter++) + getpid() + tval.tv_sec;
v2 = (counter++) * getpid() + tval.tv_usec;
SIVAL(md4_inbuf, 32, v1 ^ IVAL(md4_inbuf, 32));
SIVAL(md4_inbuf, 36, v1 ^ IVAL(md4_inbuf, 36));
mdfour(md4_outbuf, md4_inbuf, sizeof(md4_inbuf));
/* XOR everything togther in blocks of 4 bytes. */
ret = IVAL(md4_outbuf,0);
ret ^= IVAL(md4_outbuf,4);
ret ^= IVAL(md4_outbuf,8);
ret ^= IVAL(md4_outbuf,12);
DEBUG(10,("do_reseed: returning seed %lu\n", ret));
return ret;
}
/*******************************************************************
Interface to the (hopefully) good crypto random number generator.
********************************************************************/
void generate_random_buffer( unsigned char *out, int len, BOOL re_seed)
{
static BOOL done_reseed = False;
unsigned char tmp_buf[64];
unsigned char md4_buf[16];
unsigned char *p;
if(!done_reseed || re_seed) {
srandom(do_reseed());
done_reseed = True;
}
/*
* Generate random numbers in chunks of 64 bytes,
* then md4 them & copy to the output buffer.
*/
p = out;
while(len > 0) {
int i;
int copy_len = len > 16 ? 16 : len;
for( i = 0; i < 16; i++)
SIVAL(tmp_buf, i*4, random());
mdfour(md4_buf, tmp_buf, sizeof(tmp_buf));
memcpy(p, md4_buf, copy_len);
p += copy_len;
len -= copy_len;
}
}
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