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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: Fri Mar 19 07:48:01 1999 by faith@acm.org
* Public Domain 1995, 1999 Rickard E. Faith (faith@acm.org)
* This program comes with ABSOLUTELY NO WARRANTY.
*
* 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.
*
* 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
* - added Native Language Support
* 1999-03-21 aeb: Added some fragments of code from Colin Plumb.
*
*/
#include "c.h"
#include "md5.h"
#include "nls.h"
#include <fcntl.h>
#include <getopt.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>
#define BUFFERSIZE 4096
struct rngs {
const char *path;
int minlength, maxlength;
} rngs[] = {
{"/dev/random", 16, 16}, /* 16 bytes = 128 bits suffice */
{"/proc/interrupts", 0, 0},
{"/proc/slabinfo", 0, 0},
{"/proc/stat", 0, 0},
{"/dev/urandom", 32, 64},
};
#define RNGS (sizeof(rngs)/sizeof(struct rngs))
/* The basic function to hash a file */
static off_t hash_file(struct MD5Context *ctx, int fd)
{
off_t count = 0;
ssize_t r;
unsigned char buf[BUFFERSIZE];
while ((r = read(fd, buf, sizeof(buf))) > 0) {
MD5Update(ctx, buf, r);
count += r;
}
/* Separate files with a null byte */
buf[0] = '\0';
MD5Update(ctx, buf, 1);
return count;
}
static void __attribute__ ((__noreturn__)) usage(FILE * out)
{
fputs(_("\nUsage:\n"), out);
fprintf(out,
_(" %s [options]\n"), program_invocation_short_name);
fputs(_("\nOptions:\n"), out);
fputs(_(" -f, --file <file> use file as a cookie seed\n"
" -v, --verbose explain what is being done\n"
" -V, --version output version information and exit\n"
" -h, --help display this help and exit\n\n"), out);
exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}
int main(int argc, char **argv)
{
size_t i;
struct MD5Context ctx;
unsigned char digest[MD5LENGTH];
unsigned char buf[BUFFERSIZE];
int fd;
int c;
pid_t pid;
char *file = NULL;
int verbose = 0;
int r;
struct timeval tv;
struct timezone tz;
static const struct option longopts[] = {
{"file", required_argument, NULL, 'f'},
{"verbose", no_argument, NULL, 'v'},
{"version", no_argument, NULL, 'V'},
{"help", no_argument, NULL, 'h'},
{NULL, 0, NULL, 0}
};
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
while ((c =
getopt_long(argc, argv, "f:vVh", longopts, NULL)) != -1)
switch (c) {
case 'v':
verbose = 1;
break;
case 'f':
file = optarg;
break;
case 'V':
printf(_("%s from %s\n"),
program_invocation_short_name,
PACKAGE_STRING);
return EXIT_SUCCESS;
case 'h':
usage(stdout);
default:
usage(stderr);
}
MD5Init(&ctx);
gettimeofday(&tv, &tz);
MD5Update(&ctx, (unsigned char *) &tv, sizeof(tv));
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 = STDIN_FILENO;
else
fd = open(file, O_RDONLY);
if (fd < 0) {
warn(_("Could not open %s"), file);
} else {
count = hash_file(&ctx, fd);
if (verbose)
fprintf(stderr,
_("Got %d bytes from %s\n"), count,
file);
if (fd != STDIN_FILENO)
if (close(fd))
err(EXIT_FAILURE,
_("closing %s failed"), file);
}
}
for (i = 0; i < RNGS; i++) {
if ((fd = open(rngs[i].path, O_RDONLY | O_NONBLOCK)) >= 0) {
int count = sizeof(buf);
if (rngs[i].maxlength && count > rngs[i].maxlength)
count = rngs[i].maxlength;
r = read(fd, buf, count);
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 (rngs[i].minlength && r >= rngs[i].minlength)
break;
} else if (verbose)
warn(_("Could not open %s"), rngs[i].path);
}
MD5Final(digest, &ctx);
for (i = 0; i < MD5LENGTH; i++)
printf("%02x", digest[i]);
putchar('\n');
/*
* The following is important for cases like disk full,
* so shell scripts can bomb out properly rather than
* think they succeeded.
*/
if (fflush(stdout) < 0 || fclose(stdout) < 0)
return EXIT_FAILURE;
return EXIT_SUCCESS;
}
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