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/*************************************************
* Device EntropySource Source File *
* (C) 1999-2008 Jack Lloyd *
*************************************************/
#include <botan/es_dev.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <unistd.h>
namespace Botan {
/**
Close the device, if open
*/
Device_EntropySource::Device_Reader::~Device_Reader()
{
if(fd > 0) { ::close(fd); }
}
/**
Read bytes from a device file
*/
u32bit Device_EntropySource::Device_Reader::get(byte out[], u32bit length)
{
if(fd < 0)
return 0;
if(fd >= FD_SETSIZE)
return 0;
const u32bit READ_WAIT_MS = 3;
fd_set read_set;
FD_ZERO(&read_set);
FD_SET(fd, &read_set);
struct ::timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = READ_WAIT_MS * 1000;
if(::select(fd + 1, &read_set, 0, 0, &timeout) < 0)
return 0;
if(!(FD_ISSET(fd, &read_set)))
return 0;
const ssize_t got = ::read(fd, out, length);
if(got <= 0)
return 0;
const u32bit ret = static_cast<u32bit>(got);
if(ret > length)
return 0;
return ret;
}
/**
Attempt to open a device
*/
int Device_EntropySource::Device_Reader::open(const std::string& pathname)
{
#ifndef O_NONBLOCK
#define O_NONBLOCK 0
#endif
#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif
const int flags = O_RDONLY | O_NONBLOCK | O_NOCTTY;
return ::open(pathname.c_str(), flags);
}
/**
Device_EntropySource constructor
*/
Device_EntropySource::Device_EntropySource(const std::vector<std::string>& fsnames)
{
for(u32bit i = 0; i != fsnames.size(); ++i)
devices.push_back(Device_Reader(Device_Reader::open(fsnames[i])));
}
/**
* Gather entropy from a RNG device
*/
u32bit Device_EntropySource::slow_poll(byte output[], u32bit length)
{
u32bit read = 0;
for(size_t i = 0; i != devices.size(); ++i)
{
read += devices[i].get(output + read, length - read);
if(read == length)
break;
}
return read;
}
/**
* Fast /dev/random and co poll: limit output to 64 bytes
*/
u32bit Device_EntropySource::fast_poll(byte output[], u32bit length)
{
return slow_poll(output, std::min<u32bit>(length, 64));
}
}
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