contrib/pam_modules/pam_passwdqc/passwdqc_random.c

   1 /*
   2  * Copyright (c) 2000-2002 by Solar Designer. See LICENSE.
   3  */
   4
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <unistd.h>
   8 #include <errno.h>
   9 #include <fcntl.h>
  10
  11 #include "passwdqc.h"
  12
  13 #define SEPARATORS                      "_,.;:-!&"
  14
  15 static int read_loop(int fd, char *buffer, int count)
  16 {
  17         int offset, block;
  18
  19         offset = 0;
  20         while (count > 0) {
  21                 block = read(fd, &buffer[offset], count);
  22
  23                 if (block < 0) {
  24                         if (errno == EINTR) continue;
  25                         return block;
  26                 }
  27                 if (!block) return offset;
  28
  29                 offset += block;
  30                 count -= block;
  31         }
  32
  33         return offset;
  34 }
  35
  36 char *_passwdqc_random(passwdqc_params_t *params)
  37 {
  38         static char output[0x100];
  39         int bits;
  40         int use_separators, count, i;
  41         unsigned int length;
  42         char *start, *end;
  43         int fd;
  44         unsigned char bytes[2];
  45
  46         if (!(bits = params->random_bits))
  47                 return NULL;
  48
  49         count = 1 + ((bits - 12) + 14) / 15;
  50         use_separators = ((bits + 11) / 12 != count);
  51
  52         length = count * 7 - 1;
  53         if (length >= sizeof(output) || (int)length > params->max)
  54                 return NULL;
  55
  56         if ((fd = open("/dev/urandom", O_RDONLY)) < 0) return NULL;
  57
  58         length = 0;
  59         do {
  60                 if (read_loop(fd, bytes, sizeof(bytes)) != sizeof(bytes)) {
  61                         close(fd);
  62                         return NULL;
  63                 }
  64
  65                 i = (((int)bytes[1] & 0x0f) << 8) | (int)bytes[0];
  66                 start = _passwdqc_wordset_4k[i];
  67                 end = memchr(start, '\0', 6);
  68                 if (!end) end = start + 6;
  69                 if (length + (end - start) >= sizeof(output) - 1) {
  70                         close(fd);
  71                         return NULL;
  72                 }
  73                 memcpy(&output[length], start, end - start);
  74                 length += end - start;
  75                 bits -= 12;
  76
  77                 if (use_separators && bits > 3) {
  78                         i = ((int)bytes[1] & 0x70) >> 4;
  79                         output[length++] = SEPARATORS[i];
  80                         bits -= 3;
  81                 } else
  82                 if (bits > 0)
  83                         output[length++] = ' ';
  84         } while (bits > 0);
  85
  86         memset(bytes, 0, sizeof(bytes));
  87         output[length] = '\0';
  88
  89         close(fd);
  90
  91         return output;
  92 }