misc-utils/mcookie.c

   1 /* mcookie.c -- Generates random numbers for xauth
   2  * Created: Fri Feb  3 10:42:48 1995 by faith@cs.unc.edu
   3  * Revised: Fri Mar 19 07:48:01 1999 by faith@acm.org
   4  * Public Domain 1995, 1999 Rickard E. Faith (faith@acm.org)
   5  * This program comes with ABSOLUTELY NO WARRANTY.
   6  *
   7  * $Id: mcookie.c,v 1.5 1997/07/06 00:13:06 aebr Exp $
   8  *
   9  * This program gathers some random bits of data and used the MD5
  10  * message-digest algorithm to generate a 128-bit hexadecimal number for
  11  * use with xauth(1).
  12  *
  13  * NOTE: Unless /dev/random is available, this program does not actually
  14  * gather 128 bits of random information, so the magic cookie generated
  15  * will be considerably easier to guess than one might expect.
  16  *
  17  * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
  18  * - added Native Language Support
  19  * 1999-03-21 aeb: Added some fragments of code from Colin Plumb.
  20  *
  21  */
  22
  23 #ifdef __linux__
  24 #define HAVE_GETTIMEOFDAY 1
  25 #endif
  26
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29 #include <fcntl.h>
  30 #include "md5.h"
  31 #ifdef HAVE_GETTIMEOFDAY
  32 #include <sys/time.h>
  33 #include <unistd.h>
  34 #endif
  35 #include "nls.h"
  36
  37 #define BUFFERSIZE 4096
  38
  39 struct rngs {
  40    const char *path;
  41    int minlength, maxlength;
  42 } rngs[] = {
  43    { "/dev/random",              16,  16 }, /* 16 bytes = 128 bits suffice */
  44    { "/proc/interrupts",          0,   0 },
  45    { "/proc/slabinfo",            0,   0 },
  46    { "/proc/stat",                0,   0 },
  47    { "/dev/urandom",             32,  64 },
  48 };
  49 #define RNGS (sizeof(rngs)/sizeof(struct rngs))
  50
  51 int Verbose = 0;
  52
  53 /* The basic function to hash a file */
  54 static off_t
  55 hash_file(struct MD5Context *ctx, int fd)
  56 {
  57    off_t count = 0;
  58    ssize_t r;
  59    unsigned char buf[BUFFERSIZE];
  60
  61    while ((r = read(fd, buf, sizeof(buf))) > 0) {
  62       MD5Update(ctx, buf, r);
  63       count += r;
  64    }
  65    /* Separate files with a null byte */
  66    buf[0] = 0;
  67    MD5Update(ctx, buf, 1);
  68    return count;
  69 }
  70
  71 int main( int argc, char **argv )
  72 {
  73    int               i;
  74    struct MD5Context ctx;
  75    unsigned char     digest[16];
  76    unsigned char     buf[BUFFERSIZE];
  77    int               fd;
  78    int               c;
  79    pid_t             pid;
  80    char              *file = NULL;
  81    int               r;
  82 #ifdef HAVE_GETTIMEOFDAY
  83    struct timeval    tv;
  84    struct timezone   tz;
  85 #else
  86    long int          t;
  87 #endif
  88
  89    setlocale(LC_ALL, "");
  90    bindtextdomain(PACKAGE, LOCALEDIR);
  91    textdomain(PACKAGE);
  92
  93    while ((c = getopt( argc, argv, "vf:" )) != -1)
  94       switch (c) {
  95       case 'v': ++Verbose;     break;
  96       case 'f': file = optarg; break;
  97       }
  98
  99    MD5Init( &ctx );
 100
 101 #ifdef HAVE_GETTIMEOFDAY
 102    gettimeofday( &tv, &tz );
 103    MD5Update( &ctx, (unsigned char *)&tv, sizeof( tv ) );
 104 #else
 105    time( &t );
 106    MD5Update( &ctx, (unsigned char *)&t, sizeof( t ) );
 107 #endif
 108    pid = getppid();
 109    MD5Update( &ctx, (unsigned char *)&pid, sizeof( pid ));
 110    pid = getpid();
 111    MD5Update( &ctx, (unsigned char *)&pid, sizeof( pid ));
 112
 113    if (file) {
 114       int count = 0;
 115
 116       if (file[0] == '-' && !file[1])
 117          fd = fileno(stdin);
 118       else
 119          fd = open( file, O_RDONLY );
 120
 121       if (fd < 0) {
 122          fprintf( stderr, _("Could not open %s\n"), file );
 123       } else {
 124          count = hash_file( &ctx, fd );
 125          if (Verbose)
 126             fprintf( stderr, _("Got %d bytes from %s\n"), count, file );
 127
 128          if (file[0] != '-' || file[1]) close( fd );
 129       }
 130    }
 131
 132    for (i = 0; i < RNGS; i++) {
 133       if ((fd = open( rngs[i].path, O_RDONLY|O_NONBLOCK )) >= 0) {
 134          int count = sizeof(buf);
 135
 136          if (rngs[i].maxlength && count > rngs[i].maxlength)
 137             count = rngs[i].maxlength;
 138          r = read( fd, buf, count );
 139          if (r > 0)
 140             MD5Update( &ctx, buf, r );
 141          else
 142             r = 0;
 143          close( fd );
 144          if (Verbose)
 145             fprintf( stderr, _("Got %d bytes from %s\n"), r, rngs[i].path );
 146          if (rngs[i].minlength && r >= rngs[i].minlength)
 147             break;
 148       } else if (Verbose)
 149          fprintf( stderr, _("Could not open %s\n"), rngs[i].path );
 150    }
 151
 152    MD5Final( digest, &ctx );
 153    for (i = 0; i < 16; i++) printf( "%02x", digest[i] );
 154    putchar ( '\n' );
 155
 156    /*
 157     * The following is important for cases like disk full, so shell scripts
 158     * can bomb out properly rather than think they succeeded.
 159     */
 160    if (fflush(stdout) < 0 || fclose(stdout) < 0)
 161       return 1;
 162
 163    return 0;
 164 }