//
//  OSSP asgui - Accounting system graphical user interface
//  Copyright (c) 2002-2004 The OSSP Project (http://www.ossp.org/)
//  Copyright (c) 2002-2004 Ralf S. Engelschall <rse@engelschall.com>
//  Copyright (c) 2002-2004 Michael Schloh von Bennewitz <michael@schloh.com>
//  Copyright (c) 2002-2004 Cable & Wireless Telecommunications Services GmbH
//
//  This file is part of OSSP asgui, an accounting system graphical user
//  interface which can be found at http://www.ossp.org/pkg/tool/asgui/.
//
//  Permission to use, copy, modify, and distribute this software for
//  any purpose with or without fee is hereby granted, provided that
//  the above copyright notice and this permission notice appear in all
//  copies.
//
//  THIS SOFTWARE IS PROVIDED ``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 THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
//  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.
//
//  as_rand.cpp: ISO C++ implementation
//

#include <fcntl.h>
#include <cerrno>

#include "as_rand.h"

#if HAVE_UNISTD_H
#include <unistd.h>
#endif // HAVE_UNISTD_H
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif // HAVE_STDLIB_H

#if TIME_WITH_SYS_TIME
#include <sys/time.h>
#include <time.h>
#else
#if HAVE_SYS_TIME_H
#include <sys/time.h>
#else
#include <time.h>
#endif // HAVE_SYS_TIME_H
#endif // TIME_WITH_SYS_TIME


namespace AS {

// Constructor
Rand::Rand(void)
{
    this->nFd = -4; // Object fresh status
    this->openDevice();   // Open the random device
//    if (this->nFd < 0)
//        throw Genexcept("Could not open /dev/urandom or /dev/random.");
}

// Destructor
Rand::~Rand(void)
{
    this->closeDevice();  // Close the random device
    this->nFd = -4; // Return this object to its fresh status
}

//
// Rand::openDevice(void)
// Open the random device associated with this object
//
void Rand::openDevice(void)
{
    struct timeval Time;

    if (this->nFd == -4) {  // -4 indicates a fresh object
        gettimeofday(&Time, 0);
        this->nFd = open("/dev/urandom", O_RDONLY);
        if (this->nFd == -1)
            this->nFd = open("/dev/random", O_RDONLY | O_NONBLOCK);
        srand((getpid() << 16) ^ getuid() ^ Time.tv_sec ^ Time.tv_usec); // Seed
    }

    // Improve randomness by stirring in entropy
    gettimeofday(&Time, 0);
    for (int nIter = (Time.tv_sec ^ Time.tv_usec) & 0x1F; nIter > 0; nIter--)
        rand();
}

//
// Rand::closeDevice(void)
// Close the random device associated with this object
//
void Rand::closeDevice(void)
{
    if (this->nFd >= 0)
        close(this->nFd);
}

//
// Rand::genData(void *pvBuf, int nBytes)
// Generate a series of random data from the system
// standard random devices /dev/[u|s]random
//
void Rand::genData(void *pBuf, int nBytes)
{
    int nRead = 0;
    int nLost = 0;
    char *szOut = (char *)pBuf;

    if (this->nFd >= 0) {
        while (nBytes > 0) {
            nRead = read(this->nFd, szOut, nBytes);
            if ((nRead < 0) && ((errno == EINTR) || (errno == EAGAIN)))
                continue;
            if (nRead <= 0) {
                if (nLost++ == 8)
                    break;
                continue;
            }
            nBytes -= nRead;
            szOut += nRead;
            nLost = 0;
        }
    }

    // For systems with no /dev/random, we do the next best thing
    for (int nIter = 0;  nIter< nBytes; nIter++)
        *szOut++ = rand() & 0xFF;
}
} // namespace AS