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 #include <roken.h>
  36
  37 #include <rand.h>
  38 #include <heim_threads.h>
  39
  40 #include "randi.h"
  41
  42 /*
  43  * Unix /dev/random
  44  */
  45
  46 int
  47 _hc_unix_device_fd(int flags, const char **fn)
  48 {
  49     static const char *rnd_devices[] = {
  50         "/dev/urandom",
  51         "/dev/random",
  52         "/dev/srandom",
  53         "/dev/arandom",
  54         NULL
  55     };
  56     const char **p;
  57
  58     for(p = rnd_devices; *p; p++) {
  59         int fd = open(*p, flags | O_NDELAY);
  60         if(fd >= 0) {
  61             if (fn)
  62                 *fn = *p;
  63             rk_cloexec(fd);
  64             return fd;
  65         }
  66     }
  67     return -1;
  68 }
  69
  70 static void
  71 unix_seed(const void *p, int size)
  72 {
  73     const unsigned char *indata = p;
  74     ssize_t count;
  75     int fd;
  76
  77     if (size < 0)
  78         return;
  79     else if (size == 0)
  80         return;
  81
  82     fd = _hc_unix_device_fd(O_RDONLY, NULL);
  83     if (fd < 0)
  84         return;
  85
  86     while (size > 0) {
  87         count = write(fd, indata, size);
  88         if (count < 0 && errno == EINTR)
  89             continue;
  90         else if (count <= 0) {
  91             close(fd);
  92             return;
  93         }
  94         indata += count;
  95         size -= count;
  96     }
  97     close(fd);
  98 }
  99
 100
 101 static int
 102 unix_bytes(unsigned char *outdata, int size)
 103 {
 104     ssize_t count;
 105     int fd;
 106
 107     if (size < 0)
 108         return 0;
 109     else if (size == 0)
 110         return 1;
 111
 112     fd = _hc_unix_device_fd(O_RDONLY, NULL);
 113     if (fd < 0)
 114         return 0;
 115
 116     while (size > 0) {
 117         count = read(fd, outdata, size);
 118         if (count < 0 && errno == EINTR)
 119             continue;
 120         else if (count <= 0) {
 121             close(fd);
 122             return 0;
 123         }
 124         outdata += count;
 125         size -= count;
 126     }
 127     close(fd);
 128
 129     return 1;
 130 }
 131
 132 static void
 133 unix_cleanup(void)
 134 {
 135 }
 136
 137 static void
 138 unix_add(const void *indata, int size, double entropi)
 139 {
 140     unix_seed(indata, size);
 141 }
 142
 143 static int
 144 unix_pseudorand(unsigned char *outdata, int size)
 145 {
 146     return unix_bytes(outdata, size);
 147 }
 148
 149 static int
 150 unix_status(void)
 151 {
 152     int fd;
 153
 154     fd = _hc_unix_device_fd(O_RDONLY, NULL);
 155     if (fd < 0)
 156         return 0;
 157     close(fd);
 158
 159     return 1;
 160 }
 161
 162 const RAND_METHOD hc_rand_unix_method = {
 163     unix_seed,
 164     unix_bytes,
 165     unix_cleanup,
 166     unix_add,
 167     unix_pseudorand,
 168     unix_status
 169 };
 170
 171 const RAND_METHOD *
 172 RAND_unix_method(void)
 173 {
 174     return &hc_rand_unix_method;
 175 }