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      1 /*	$NetBSD: rand-unix.c,v 1.2 2017/01/28 21:31:47 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2006 Kungliga Tekniska Hgskolan
      5  * (Royal Institute of Technology, Stockholm, Sweden).
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  *
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  *
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * 3. Neither the name of the Institute nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <config.h>
     37 #include <krb5/roken.h>
     38 
     39 #include <rand.h>
     40 #include <heim_threads.h>
     41 
     42 #include "randi.h"
     43 
     44 /*
     45  * Unix /dev/random
     46  */
     47 
     48 int
     49 _hc_unix_device_fd(int flags, const char **fn)
     50 {
     51     static const char *rnd_devices[] = {
     52 	"/dev/urandom",
     53 	"/dev/random",
     54 	"/dev/srandom",
     55 	"/dev/arandom",
     56 	NULL
     57     };
     58     const char **p;
     59 
     60     for(p = rnd_devices; *p; p++) {
     61 	int fd = open(*p, flags | O_NDELAY);
     62 	if(fd >= 0) {
     63 	    if (fn)
     64 		*fn = *p;
     65 	    rk_cloexec(fd);
     66 	    return fd;
     67 	}
     68     }
     69     return -1;
     70 }
     71 
     72 static void
     73 unix_seed(const void *p, int size)
     74 {
     75     const unsigned char *indata = p;
     76     ssize_t count;
     77     int fd;
     78 
     79     if (size < 0)
     80 	return;
     81     else if (size == 0)
     82 	return;
     83 
     84     fd = _hc_unix_device_fd(O_RDONLY, NULL);
     85     if (fd < 0)
     86 	return;
     87 
     88     while (size > 0) {
     89 	count = write(fd, indata, size);
     90 	if (count < 0 && errno == EINTR)
     91 	    continue;
     92 	else if (count <= 0) {
     93 	    close(fd);
     94 	    return;
     95 	}
     96 	indata += count;
     97 	size -= count;
     98     }
     99     close(fd);
    100 }
    101 
    102 
    103 static int
    104 unix_bytes(unsigned char *outdata, int size)
    105 {
    106     ssize_t count;
    107     int fd;
    108 
    109     if (size < 0)
    110 	return 0;
    111     else if (size == 0)
    112 	return 1;
    113 
    114     fd = _hc_unix_device_fd(O_RDONLY, NULL);
    115     if (fd < 0)
    116 	return 0;
    117 
    118     while (size > 0) {
    119 	count = read(fd, outdata, size);
    120 	if (count < 0 && errno == EINTR)
    121 	    continue;
    122 	else if (count <= 0) {
    123 	    close(fd);
    124 	    return 0;
    125 	}
    126 	outdata += count;
    127 	size -= count;
    128     }
    129     close(fd);
    130 
    131     return 1;
    132 }
    133 
    134 static void
    135 unix_cleanup(void)
    136 {
    137 }
    138 
    139 static void
    140 unix_add(const void *indata, int size, double entropi)
    141 {
    142     unix_seed(indata, size);
    143 }
    144 
    145 static int
    146 unix_pseudorand(unsigned char *outdata, int size)
    147 {
    148     return unix_bytes(outdata, size);
    149 }
    150 
    151 static int
    152 unix_status(void)
    153 {
    154     int fd;
    155 
    156     fd = _hc_unix_device_fd(O_RDONLY, NULL);
    157     if (fd < 0)
    158 	return 0;
    159     close(fd);
    160 
    161     return 1;
    162 }
    163 
    164 const RAND_METHOD hc_rand_unix_method = {
    165     unix_seed,
    166     unix_bytes,
    167     unix_cleanup,
    168     unix_add,
    169     unix_pseudorand,
    170     unix_status
    171 };
    172 
    173 const RAND_METHOD *
    174 RAND_unix_method(void)
    175 {
    176     return &hc_rand_unix_method;
    177 }
    178