1/*	$NetBSD: rand-timer.c,v 1.2 2017/01/28 21:31:47 christos Exp $	*/
2
3/*
4 * Copyright (c) 1995, 1996, 1997, 1999, 2007 Kungliga Tekniska H��gskolan
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
41#include "randi.h"
42
43#ifndef WIN32 /* don't bother with this on windows */
44
45static volatile int counter;
46static volatile unsigned char *gdata; /* Global data */
47static volatile int igdata;	/* Index into global data */
48static int gsize;
49
50static
51RETSIGTYPE
52sigALRM(int sig)
53{
54    if (igdata < gsize)
55	gdata[igdata++] ^= counter & 0xff;
56
57#ifndef HAVE_SIGACTION
58    signal(SIGALRM, sigALRM); /* Reinstall SysV signal handler */
59#endif
60    SIGRETURN(0);
61}
62
63#ifndef HAVE_SETITIMER
64static void
65pacemaker(struct timeval *tv)
66{
67    fd_set fds;
68    pid_t pid;
69    pid = getppid();
70    while(1){
71	FD_ZERO(&fds);
72	FD_SET(0, &fds);
73	select(1, &fds, NULL, NULL, tv);
74	kill(pid, SIGALRM);
75    }
76}
77#endif
78
79#ifdef HAVE_SIGACTION
80/* XXX ugly hack, should perhaps use function from roken */
81static RETSIGTYPE
82(*fake_signal(int sig, RETSIGTYPE (*f)(int)))(int)
83{
84    struct sigaction sa, osa;
85    sa.sa_handler = f;
86    sa.sa_flags = 0;
87    sigemptyset(&sa.sa_mask);
88    sigaction(sig, &sa, &osa);
89    return osa.sa_handler;
90}
91#define signal(S, F) fake_signal((S), (F))
92#endif
93
94#endif /* WIN32*/
95
96/*
97 *
98 */
99
100static void
101timer_seed(const void *indata, int size)
102{
103}
104
105static int
106timer_bytes(unsigned char *outdata, int size)
107{
108#ifdef WIN32
109    return 0;
110#else /* WIN32 */
111    struct itimerval tv, otv;
112    RETSIGTYPE (*osa)(int);
113    int i, j;
114#ifndef HAVE_SETITIMER
115    RETSIGTYPE (*ochld)(int);
116    pid_t pid;
117#endif
118
119    gdata = outdata;
120    gsize = size;
121    igdata = 0;
122
123    osa = signal(SIGALRM, sigALRM);
124
125    /* Start timer */
126    tv.it_value.tv_sec = 0;
127    tv.it_value.tv_usec = 10 * 1000; /* 10 ms */
128    tv.it_interval = tv.it_value;
129#ifdef HAVE_SETITIMER
130    setitimer(ITIMER_REAL, &tv, &otv);
131#else
132    ochld = signal(SIGCHLD, SIG_IGN);
133    pid = fork();
134    if(pid == -1){
135	signal(SIGCHLD, ochld != SIG_ERR ? ochld : SIG_DFL);
136	des_not_rand_data(data, size);
137	return;
138    }
139    if(pid == 0)
140	pacemaker(&tv.it_interval);
141#endif
142
143    for(i = 0; i < 4; i++) {
144	for (igdata = 0; igdata < size;) /* igdata++ in sigALRM */
145	    counter++;
146	for (j = 0; j < size; j++) /* Only use 2 bits each lap */
147	    gdata[j] = (gdata[j]>>2) | (gdata[j]<<6);
148    }
149#ifdef HAVE_SETITIMER
150    setitimer(ITIMER_REAL, &otv, 0);
151#else
152    kill(pid, SIGKILL);
153    while(waitpid(pid, NULL, 0) != pid);
154    signal(SIGCHLD, ochld != SIG_ERR ? ochld : SIG_DFL);
155#endif
156    signal(SIGALRM, osa != SIG_ERR ? osa : SIG_DFL);
157
158    return 1;
159#endif
160}
161
162static void
163timer_cleanup(void)
164{
165}
166
167static void
168timer_add(const void *indata, int size, double entropi)
169{
170}
171
172static int
173timer_pseudorand(unsigned char *outdata, int size)
174{
175    return timer_bytes(outdata, size);
176}
177
178static int
179timer_status(void)
180{
181#ifdef WIN32
182    return 0;
183#else
184    return 1;
185#endif
186}
187
188#if defined(__GNUC__) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901)
189const RAND_METHOD hc_rand_timer_method = {
190    .seed = timer_seed,
191    .bytes = timer_bytes,
192    .cleanup = timer_cleanup,
193    .add = timer_add,
194    .pseudorand = timer_pseudorand,
195    .status = timer_status
196};
197#else
198const RAND_METHOD hc_rand_timer_method = {
199    timer_seed,
200    timer_bytes,
201    timer_cleanup,
202    timer_add,
203    timer_pseudorand,
204    timer_status
205};
206#endif
207
208const RAND_METHOD *
209RAND_timer_method(void)
210{
211    return &hc_rand_timer_method;
212}
213