lib/hcrypto/rand-unix.c

   1 /*
   2  * Copyright (c) 2006 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include <config.h>
  35
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <rand.h>
  39 #include <heim_threads.h>
  40
  41 #include <roken.h>
  42
  43 #include "randi.h"
  44
  45 /*
  46  * Unix /dev/random
  47  */
  48
  49 int
  50 _hc_unix_device_fd(int flags, const char **fn)
  51 {
  52     static const char *rnd_devices[] = {
  53         "/dev/urandom",
  54         "/dev/random",
  55         "/dev/srandom",
  56         "/dev/arandom",
  57         NULL
  58     };
  59     const char **p;
  60
  61     for(p = rnd_devices; *p; p++) {
  62         int fd = open(*p, flags | O_NDELAY);
  63         if(fd >= 0) {
  64             if (fn)
  65                 *fn = *p;
  66             rk_cloexec(fd);
  67             return fd;
  68         }
  69     }
  70     return -1;
  71 }
  72
  73 static void
  74 unix_seed(const void *indata, int size)
  75 {
  76 }
  77
  78
  79 static int
  80 unix_bytes(unsigned char *outdata, int size)
  81 {
  82     ssize_t count;
  83     int fd;
  84
  85     if (size < 0)
  86         return 0;
  87     else if (size == 0)
  88         return 1;
  89
  90     fd = _hc_unix_device_fd(O_RDONLY, NULL);
  91     if (fd < 0)
  92         return 0;
  93
  94     while (size > 0) {
  95         count = read(fd, outdata, size);
  96         if (count < 0 && errno == EINTR)
  97             continue;
  98         else if (count <= 0) {
  99             close(fd);
 100             return 0;
 101         }
 102         outdata += count;
 103         size -= count;
 104     }
 105     close(fd);
 106
 107     return 1;
 108 }
 109
 110 static void
 111 unix_cleanup(void)
 112 {
 113 }
 114
 115 static void
 116 unix_add(const void *indata, int size, double entropi)
 117 {
 118     unix_seed(indata, size);
 119 }
 120
 121 static int
 122 unix_pseudorand(unsigned char *outdata, int size)
 123 {
 124     return unix_bytes(outdata, size);
 125 }
 126
 127 static int
 128 unix_status(void)
 129 {
 130     int fd;
 131
 132     fd = _hc_unix_device_fd(O_RDONLY, NULL);
 133     if (fd < 0)
 134         return 0;
 135     close(fd);
 136
 137     return 1;
 138 }
 139
 140 const RAND_METHOD hc_rand_unix_method = {
 141     unix_seed,
 142     unix_bytes,
 143     unix_cleanup,
 144     unix_add,
 145     unix_pseudorand,
 146     unix_status
 147 };
 148
 149 const RAND_METHOD *
 150 RAND_unix_method(void)
 151 {
 152     return &hc_rand_unix_method;
 153 }