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 #ifdef HAVE_CONFIG_H
  35 #include <config.h>
  36 #endif
  37
  38 RCSID("$Id$");
  39
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <rand.h>
  43
  44 #include <roken.h>
  45
  46 #include "randi.h"
  47
  48 /*
  49  * Unix /dev/random
  50  */
  51
  52 static int
  53 get_device_fd(int flags)
  54 {
  55     static const char *rnd_devices[] = {
  56         "/dev/urandom",
  57         "/dev/random",
  58         "/dev/srandom",
  59         "/dev/arandom",
  60         NULL
  61     };
  62     const char **p;
  63
  64     for(p = rnd_devices; *p; p++) {
  65         int fd = open(*p, flags | O_NDELAY);
  66         if(fd >= 0)
  67             return fd;
  68     }
  69     return -1;
  70 }
  71
  72 static void
  73 unix_seed(const void *indata, int size)
  74 {
  75     int fd;
  76
  77     if (size <= 0)
  78         return;
  79
  80     fd = get_device_fd(O_WRONLY);
  81     if (fd < 0)
  82         return;
  83
  84     write(fd, indata, size);
  85     close(fd);
  86
  87 }
  88
  89 static int
  90 unix_bytes(unsigned char *outdata, int size)
  91 {
  92     ssize_t count;
  93     int fd;
  94
  95     if (size <= 0)
  96         return 0;
  97
  98     fd = get_device_fd(O_RDONLY);
  99     if (fd < 0)
 100         return 0;
 101
 102     while (size > 0) {
 103         count = read (fd, outdata, size);
 104         if (count < 0 && errno == EINTR)
 105             continue;
 106         else if (count <= 0) {
 107             close(fd);
 108             return 0;
 109         }
 110         outdata += count;
 111         size -= count;
 112     }
 113     close(fd);
 114
 115     return 1;
 116 }
 117
 118 static void
 119 unix_cleanup(void)
 120 {
 121 }
 122
 123 static void
 124 unix_add(const void *indata, int size, double entropi)
 125 {
 126     unix_seed(indata, size);
 127 }
 128
 129 static int
 130 unix_pseudorand(unsigned char *outdata, int size)
 131 {
 132     return unix_bytes(outdata, size);
 133 }
 134
 135 static int
 136 unix_status(void)
 137 {
 138     int fd;
 139
 140     fd = get_device_fd(O_RDONLY);
 141     if (fd < 0)
 142         return 0;
 143     close(fd);
 144
 145     return 1;
 146 }
 147
 148 const RAND_METHOD hc_rand_unix_method = {
 149     unix_seed,
 150     unix_bytes,
 151     unix_cleanup,
 152     unix_add,
 153     unix_pseudorand,
 154     unix_status
 155 };
 156
 157 const RAND_METHOD *
 158 RAND_unix_method(void)
 159 {
 160     return &hc_rand_unix_method;
 161 }