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/* mcookie.c -- Generates random numbers for xauth
* Created: Fri Feb 3 10:42:48 1995 by faith@cs.unc.edu
* Revised: Mon Sep 25 23:44:43 1995 by r.faith@ieee.org
* Public Domain 1995 Rickard E. Faith (faith@cs.unc.edu)
* This program comes with ABSOLUTELY NO WARRANTY.
*
* $Id: mcookie.c,v 1.5 1997/07/06 00:13:06 aebr Exp $
*
* This program gathers some random bits of data and used the MD5
* message-digest algorithm to generate a 128-bit hexadecimal number for
* use with xauth(1).
*
* NOTE: Unless /dev/random is available, this program does not actually
* gather 128 bits of random information, so the magic cookie generated
* will be considerably easier to guess than one might expect.
*/
#ifdef __linux__
#define HAVE_GETTIMEOFDAY 1
#endif
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include "md5.h"
#if HAVE_GETTIMEOFDAY
#include <sys/time.h>
#include <unistd.h>
#endif
#define MAXBUFFERSIZE 512
struct rngs {
const char *path;
int length;
} rngs[] = {
{ "/dev/random", 16 },
{ "/dev/urandom", 128 },
{ "/proc/stat", MAXBUFFERSIZE },
{ "/proc/loadavg", MAXBUFFERSIZE },
{ "/dev/audio", MAXBUFFERSIZE },
};
#define RNGS (sizeof(rngs)/sizeof(struct rngs))
int Verbose = 0;
int main( int argc, char **argv )
{
int i;
struct MD5Context ctx;
unsigned char digest[16];
unsigned char buf[MAXBUFFERSIZE];
int fd;
int c;
pid_t pid;
char *file = NULL;
int r;
#if HAVE_GETTIMEOFDAY
struct timeval tv;
struct timezone tz;
#else
long int t;
#endif
while ((c = getopt( argc, argv, "vf:" )) != EOF)
switch (c) {
case 'v': ++Verbose; break;
case 'f': file = optarg; break;
}
MD5Init( &ctx );
#if HAVE_GETTIMEOFDAY
gettimeofday( &tv, &tz );
MD5Update( &ctx, (unsigned char *)&tv, sizeof( tv ) );
#else
time( &t );
MD5Update( &ctx, (unsigned char *)&t, sizeof( t ) );
#endif
pid = getppid();
MD5Update( &ctx, (unsigned char *)&pid, sizeof( pid ));
pid = getpid();
MD5Update( &ctx, (unsigned char *)&pid, sizeof( pid ));
if (file) {
int count = 0;
if (file[0] == '-' && !file[1]) fd = fileno(stdin);
else if ((fd = open( file, O_RDONLY )) <0) {
fprintf( stderr, "Could not open %s\n", file );
}
while ((r = read( fd, buf, sizeof( buf ) )) > 0) {
MD5Update( &ctx, buf, r );
count += r;
}
if (Verbose)
fprintf( stderr, "Got %d bytes from %s\n", count, file );
if (file[0] != '-' || file[1]) close( fd );
}
for (i = 0; i < RNGS; i++) {
if ((fd = open( rngs[i].path, O_RDONLY|O_NONBLOCK )) >= 0) {
r = read( fd, buf, sizeof( buf ) );
if (r > 0)
MD5Update( &ctx, buf, r );
else
r = 0;
close( fd );
if (Verbose)
fprintf( stderr, "Got %d bytes from %s\n", r, rngs[i].path );
if (r >= rngs[i].length) break;
} else if (Verbose)
fprintf( stderr, "Could not open %s\n", rngs[i].path );
}
MD5Final( digest, &ctx );
for (i = 0; i < 16; i++) printf( "%02x", digest[i] );
putchar ( '\n' );
return 0;
}
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