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/*
* EGD EntropySource
* (C) 1999-2009 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/internal/es_egd.h>
#include <botan/parsing.h>
#include <botan/exceptn.h>
#include <cstring>
#include <stdexcept>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#ifndef PF_LOCAL
#define PF_LOCAL PF_UNIX
#endif
namespace Botan {
EGD_EntropySource::EGD_Socket::EGD_Socket(const std::string& path) :
socket_path(path), m_fd(-1)
{
}
/**
* Attempt a connection to an EGD/PRNGD socket
*/
int EGD_EntropySource::EGD_Socket::open_socket(const std::string& path)
{
int fd = ::socket(PF_LOCAL, SOCK_STREAM, 0);
if(fd >= 0)
{
sockaddr_un addr;
std::memset(&addr, 0, sizeof(addr));
addr.sun_family = PF_LOCAL;
if(sizeof(addr.sun_path) < path.length() + 1)
throw std::invalid_argument("EGD socket path is too long");
std::strncpy(addr.sun_path, path.c_str(), sizeof(addr.sun_path));
int len = sizeof(addr.sun_family) + std::strlen(addr.sun_path) + 1;
if(::connect(fd, reinterpret_cast<struct ::sockaddr*>(&addr), len) < 0)
{
::close(fd);
fd = -1;
}
}
return fd;
}
/**
* Attempt to read entropy from EGD
*/
size_t EGD_EntropySource::EGD_Socket::read(byte outbuf[], size_t length)
{
if(length == 0)
return 0;
if(m_fd < 0)
{
m_fd = open_socket(socket_path);
if(m_fd < 0)
return 0;
}
try
{
// 1 == EGD command for non-blocking read
byte egd_read_command[2] = {
1, static_cast<byte>(std::min<size_t>(length, 255)) };
if(::write(m_fd, egd_read_command, 2) != 2)
throw std::runtime_error("Writing entropy read command to EGD failed");
byte out_len = 0;
if(::read(m_fd, &out_len, 1) != 1)
throw std::runtime_error("Reading response length from EGD failed");
if(out_len > egd_read_command[1])
throw std::runtime_error("Bogus length field received from EGD");
ssize_t count = ::read(m_fd, outbuf, out_len);
if(count != out_len)
throw std::runtime_error("Reading entropy result from EGD failed");
return static_cast<size_t>(count);
}
catch(std::exception)
{
this->close();
// Will attempt to reopen next poll
}
return 0;
}
void EGD_EntropySource::EGD_Socket::close()
{
if(m_fd > 0)
{
::close(m_fd);
m_fd = -1;
}
}
/**
* EGD_EntropySource constructor
*/
EGD_EntropySource::EGD_EntropySource(const std::vector<std::string>& paths)
{
for(size_t i = 0; i != paths.size(); ++i)
sockets.push_back(EGD_Socket(paths[i]));
}
EGD_EntropySource::~EGD_EntropySource()
{
for(size_t i = 0; i != sockets.size(); ++i)
sockets[i].close();
sockets.clear();
}
/**
* Gather Entropy from EGD
*/
void EGD_EntropySource::poll(Entropy_Accumulator& accum)
{
size_t go_get = std::min<size_t>(accum.desired_remaining_bits() / 8, 32);
secure_vector<byte>& io_buffer = accum.get_io_buffer(go_get);
for(size_t i = 0; i != sockets.size(); ++i)
{
size_t got = sockets[i].read(&io_buffer[0], io_buffer.size());
if(got)
{
accum.add(&io_buffer[0], got, 6);
break;
}
}
}
}
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