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// **********************************************************************
//
// Copyright (c) 2003-2016 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// **********************************************************************
#ifdef _WIN32
# define _CRT_RAND_S
#endif
#include <IceUtil/Random.h>
#include <IceUtil/Mutex.h>
#include <IceUtil/MutexPtrLock.h>
#ifndef _WIN32
# include <unistd.h>
# include <fcntl.h>
#endif
using namespace std;
using namespace IceUtil;
#if !defined(_WIN32)
namespace
{
//
// The static mutex is required to lazy initialize the file
// descriptor for /dev/urandom (Unix)
//
// Also, unfortunately on Linux (at least up to 2.6.9), concurrent
// access to /dev/urandom can return the same value. Search for
// "Concurrent access to /dev/urandom" in the linux-kernel mailing
// list archive for additional details. Since /dev/urandom on other
// platforms is usually a port from Linux, this problem could be
// widespread. Therefore, we serialize access to /dev/urandom using a
// static mutex.
//
Mutex* staticMutex = 0;
int fd = -1;
//
// Callback to use with pthread_atfork to reset the "/dev/urandom"
// fd state. We don't need to close the fd here as that is done
// during static destruction.
//
extern "C"
{
void childAtFork()
{
if(fd != -1)
{
fd = -1;
}
}
}
class Init
{
public:
Init()
{
staticMutex = new IceUtil::Mutex;
//
// Register a callback to reset the "/dev/urandom" fd
// state after fork.
//
pthread_atfork(0, 0, &childAtFork);
}
~Init()
{
if(fd != -1)
{
close(fd);
fd = -1;
}
delete staticMutex;
staticMutex = 0;
}
};
Init init;
}
#endif
void
IceUtilInternal::generateRandom(char* buffer, size_t size)
{
#ifdef _WIN32
int i = 0;
const size_t randSize = sizeof(unsigned int);
while(size - i >= randSize)
{
unsigned int r = 0;
errno_t err = rand_s(&r);
if(err != 0)
{
throw SyscallException(__FILE__, __LINE__, errno);
}
memcpy(buffer + i, &r, randSize);
i += randSize;
}
if(size - i > 0)
{
assert(size - i < randSize);
unsigned int r = 0;
errno_t err = rand_s(&r);
if(err != 0)
{
throw SyscallException(__FILE__, __LINE__, errno);
}
memcpy(buffer + i, &r, size - i);
}
#else
//
// Serialize access to /dev/urandom; see comment above.
//
IceUtilInternal::MutexPtrLock<IceUtil::Mutex> lock(staticMutex);
if(fd == -1)
{
fd = open("/dev/urandom", O_RDONLY);
if(fd == -1)
{
throw SyscallException(__FILE__, __LINE__, errno);
}
}
//
// Limit the number of attempts to 20 reads to avoid
// a potential "for ever" loop
//
int reads = 0;
size_t index = 0;
while(reads <= 20 && index != size)
{
ssize_t bytesRead = read(fd, buffer + index, size - index);
if(bytesRead == -1 && errno != EINTR)
{
throw SyscallException(__FILE__, __LINE__, errno);
}
else
{
index += bytesRead;
reads++;
}
}
if(index != size)
{
throw SyscallException(__FILE__, __LINE__, 0);
}
#endif
}
unsigned int
IceUtilInternal::random(int limit)
{
unsigned int r;
#ifdef _WIN32
errno_t err = rand_s(&r);
if(err != 0)
{
throw SyscallException(__FILE__, __LINE__, errno);
}
#else
generateRandom(reinterpret_cast<char*>(&r), sizeof(unsigned int));
#endif
if(limit > 0)
{
r = r % limit;
}
return r;
}
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