/*                      _             _
**  _ __ ___   ___   __| |    ___ ___| |  mod_ssl
** | '_ ` _ \ / _ \ / _` |   / __/ __| |  Apache Interface to OpenSSL
** | | | | | | (_) | (_| |   \__ \__ \ |  www.modssl.org
** |_| |_| |_|\___/ \__,_|___|___/___/_|  ftp.modssl.org
**                      |_____|
**  ssl_engine_rand.c
**  Random Number Generator Seeding
*/

/* ====================================================================
 * Copyright (c) 1998-2000 Ralf S. Engelschall. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by
 *     Ralf S. Engelschall <rse@engelschall.com> for use in the
 *     mod_ssl project (http://www.modssl.org/)."
 *
 * 4. The names "mod_ssl" must not be used to endorse or promote
 *    products derived from this software without prior written
 *    permission. For written permission, please contact
 *    rse@engelschall.com.
 *
 * 5. Products derived from this software may not be called "mod_ssl"
 *    nor may "mod_ssl" appear in their names without prior
 *    written permission of Ralf S. Engelschall.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by
 *     Ralf S. Engelschall <rse@engelschall.com> for use in the
 *     mod_ssl project (http://www.modssl.org/)."
 *
 * THIS SOFTWARE IS PROVIDED BY RALF S. ENGELSCHALL ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL RALF S. ENGELSCHALL OR
 * HIS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 */
                             /* ``The generation of random
                                  numbers is too important
                                  to be left to chance.'' */

#include "mod_ssl.h"


/*  _________________________________________________________________
**
**  Support for better seeding of SSL library's RNG
**  _________________________________________________________________
*/

static int ssl_rand_choosenum(int, int);
static int ssl_rand_feedfp(pool *, FILE *, int);

int ssl_rand_seed(server_rec *s, pool *p, ssl_rsctx_t nCtx, char *prefix)
{
    SSLModConfigRec *mc;
    array_header *apRandSeed;
    ssl_randseed_t *pRandSeeds;
    ssl_randseed_t *pRandSeed;
    unsigned char stackdata[256];
    int nReq, nDone;
    FILE *fp;
    int i, n, l;
    time_t t;
    pid_t pid;

    mc = myModConfig();
    nReq  = 0;
    nDone = 0;
    apRandSeed = mc->aRandSeed;
    pRandSeeds = (ssl_randseed_t *)apRandSeed->elts;
    for (i = 0; i < apRandSeed->nelts; i++) {
        pRandSeed = &pRandSeeds[i];
        if (pRandSeed->nCtx == nCtx) {
            nReq += pRandSeed->nBytes;
            if (pRandSeed->nSrc == SSL_RSSRC_FILE) {
                /*
                 * seed in contents of an external file
                 */
                if ((fp = ap_pfopen(p, pRandSeed->cpPath, "r")) == NULL)
                    continue;
                nDone += ssl_rand_feedfp(p, fp, pRandSeed->nBytes);
                ap_pfclose(p, fp);
            }
            else if (pRandSeed->nSrc == SSL_RSSRC_EXEC) {
                /*
                 * seed in contents generated by an external program
                 */
                if ((fp = ssl_util_ppopen(s, p, ap_psprintf(p, "%s %d",
                                          pRandSeed->cpPath, pRandSeed->nBytes))) == NULL)
                    continue;
                nDone += ssl_rand_feedfp(p, fp, pRandSeed->nBytes);
                ssl_util_ppclose(s, p, fp);
            }
#if SSL_LIBRARY_VERSION >= 0x00905100
            else if (pRandSeed->nSrc == SSL_RSSRC_EGD) {
                /*
                 * seed in contents provided by the external
                 * Entropy Gathering Daemon (EGD)
                 */
                if ((n = RAND_egd(pRandSeed->cpPath)) == -1)
                    continue;
                nDone += n;
            }
#endif
            else if (pRandSeed->nSrc == SSL_RSSRC_BUILTIN) {
                /*
                 * seed in the current time (usually just 4 bytes)
                 */
                t = time(NULL);
                l = sizeof(time_t);
                RAND_seed((unsigned char *)&t, l);
                nDone += l;

                /*
                 * seed in the current process id (usually just 4 bytes)
                 */
                pid = getpid();
                l = sizeof(pid_t);
                RAND_seed((unsigned char *)&pid, l);
                nDone += l;
                
                /*
                 * seed in some current state of the run-time stack (128 bytes)
                 */
                n = ssl_rand_choosenum(0, sizeof(stackdata)-128-1);
                RAND_seed(stackdata+n, 128);
                nDone += 128;

                /*
                 * seed in an 1KB extract of the current scoreboard
                 */
                if (ap_scoreboard_image != NULL) {
                    n = ssl_rand_choosenum(0, SCOREBOARD_SIZE-1024-1);
                    RAND_seed((unsigned char *)ap_scoreboard_image+n, 1024);
                    nDone += 1024;
                }
            }
        }
    }
    ssl_log(s, SSL_LOG_INFO, "%sSeeding PRNG with %d bytes of entropy", prefix, nDone);

#if SSL_LIBRARY_VERSION >= 0x00905100
    if (RAND_status() == 0)
        ssl_log(s, SSL_LOG_WARN, "%sPRNG still contains not sufficient entropy!", prefix);
#endif
    return nDone;
}

#define BUFSIZE 8192

static int ssl_rand_feedfp(pool *p, FILE *fp, int nReq)
{
    int nDone;
    unsigned char caBuf[BUFSIZE];
    int nBuf;
    int nRead;
    int nTodo;

    nDone = 0;
    nRead = BUFSIZE;
    nTodo = nReq;
    while (1) {
        if (nReq > 0)
            nRead = (nTodo < BUFSIZE ? nTodo : BUFSIZE);
        if ((nBuf = (int)fread(caBuf, 1, nRead, fp)) <= 0)
            break;
        RAND_seed(caBuf, nBuf);
        nDone += nBuf;
        if (nReq > 0) {
            nTodo -= nBuf;
            if (nTodo <= 0)
                break;
        }
    }
    return nDone;
}

static int ssl_rand_choosenum(int l, int h)
{
    int i;
    char buf[50];

    srand((unsigned int)time(NULL));
    ap_snprintf(buf, sizeof(buf), "%.0f",
                (((double)(rand()%RAND_MAX)/RAND_MAX)*(h-l)));
    i = atoi(buf)+1;
    if (i < l) i = l;
    if (i > h) i = h;
    return i;
}

