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C++

// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012-2017 OpenVPN Inc.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License Version 3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program in the COPYING file.
// If not, see <http://www.gnu.org/licenses/>.
#ifndef OPENVPN_RANDOM_DEVURAND_H
#define OPENVPN_RANDOM_DEVURAND_H
#include <sys/types.h> // for open()
#include <sys/stat.h> // for open()
#include <fcntl.h> // for open()
#include <unistd.h> // for read()
#include <openvpn/common/scoped_fd.hpp>
#include <openvpn/random/randapi.hpp>
namespace openvpn {
class DevURand : public RandomAPI
{
public:
OPENVPN_EXCEPTION(dev_urand_error);
typedef RCPtr<DevURand> Ptr;
DevURand()
: dev_urandom(::open("/dev/urandom", O_RDONLY))
{
if (!dev_urandom.defined())
throw dev_urand_error("init failed");
}
// Random algorithm name
virtual std::string name() const
{
return "DevURand";
}
// Return true if algorithm is crypto-strength
virtual bool is_crypto() const
{
return true;
}
// Fill buffer with random bytes
virtual void rand_bytes(unsigned char *buf, size_t size)
{
if (!rndbytes(buf, size))
throw dev_urand_error("rand_bytes failed");
}
// Like rand_bytes, but don't throw exception.
// Return true on successs, false on fail.
virtual bool rand_bytes_noexcept(unsigned char *buf, size_t size)
{
return rndbytes(buf, size);
}
private:
bool rndbytes(unsigned char *buf, size_t size)
{
const ssize_t actual = ::read(dev_urandom(), buf, size);
return size == actual;
}
ScopedFD dev_urandom;
};
}
#endif