boost/asio/detail/resolver_service.hpp
//
// resolver_service.hpp
// ~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#ifndef BOOST_ASIO_DETAIL_RESOLVER_SERVICE_HPP
#define BOOST_ASIO_DETAIL_RESOLVER_SERVICE_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include <boost/asio/detail/push_options.hpp>
#include <boost/asio/detail/push_options.hpp>
#include <cstring>
#include <boost/scoped_ptr.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/weak_ptr.hpp>
#include <boost/asio/detail/pop_options.hpp>
#include <boost/asio/error.hpp>
#include <boost/asio/io_service.hpp>
#include <boost/asio/detail/bind_handler.hpp>
#include <boost/asio/detail/mutex.hpp>
#include <boost/asio/detail/noncopyable.hpp>
#include <boost/asio/detail/service_base.hpp>
#include <boost/asio/detail/socket_ops.hpp>
#include <boost/asio/detail/socket_types.hpp>
#include <boost/asio/detail/thread.hpp>
namespace boost {
namespace asio {
namespace detail {
template <typename Protocol>
class resolver_service
: public boost::asio::detail::service_base<resolver_service<Protocol> >
{
private:
// Helper class to perform exception-safe cleanup of addrinfo objects.
class auto_addrinfo
: private boost::asio::detail::noncopyable
{
public:
explicit auto_addrinfo(boost::asio::detail::addrinfo_type* ai)
: ai_(ai)
{
}
~auto_addrinfo()
{
if (ai_)
socket_ops::freeaddrinfo(ai_);
}
operator boost::asio::detail::addrinfo_type*()
{
return ai_;
}
private:
boost::asio::detail::addrinfo_type* ai_;
};
public:
// The implementation type of the resolver. The shared pointer is used as a
// cancellation token to indicate to the background thread that the operation
// has been cancelled.
typedef boost::shared_ptr<void> implementation_type;
struct noop_deleter { void operator()(void*) {} };
// The endpoint type.
typedef typename Protocol::endpoint endpoint_type;
// The query type.
typedef typename Protocol::resolver_query query_type;
// The iterator type.
typedef typename Protocol::resolver_iterator iterator_type;
// Constructor.
resolver_service(boost::asio::io_service& io_service)
: boost::asio::detail::service_base<
resolver_service<Protocol> >(io_service),
mutex_(),
work_io_service_(new boost::asio::io_service),
work_(new boost::asio::io_service::work(*work_io_service_)),
work_thread_(0)
{
}
// Destructor.
~resolver_service()
{
shutdown_service();
}
// Destroy all user-defined handler objects owned by the service.
void shutdown_service()
{
work_.reset();
if (work_io_service_)
{
work_io_service_->stop();
if (work_thread_)
{
work_thread_->join();
work_thread_.reset();
}
work_io_service_.reset();
}
}
// Construct a new resolver implementation.
void construct(implementation_type& impl)
{
impl.reset(static_cast<void*>(0), noop_deleter());
}
// Destroy a resolver implementation.
void destroy(implementation_type&)
{
}
// Cancel pending asynchronous operations.
void cancel(implementation_type& impl)
{
impl.reset(static_cast<void*>(0), noop_deleter());
}
// Resolve a query to a list of entries.
iterator_type resolve(implementation_type&, const query_type& query,
boost::system::error_code& ec)
{
boost::asio::detail::addrinfo_type* address_info = 0;
std::string host_name = query.host_name();
std::string service_name = query.service_name();
boost::asio::detail::addrinfo_type hints = query.hints();
socket_ops::getaddrinfo(host_name.length() ? host_name.c_str() : 0,
service_name.c_str(), &hints, &address_info, ec);
auto_addrinfo auto_address_info(address_info);
if (ec)
return iterator_type();
return iterator_type::create(address_info, host_name, service_name);
}
template <typename Handler>
class resolve_query_handler
{
public:
resolve_query_handler(implementation_type impl, const query_type& query,
boost::asio::io_service& io_service, Handler handler)
: impl_(impl),
query_(query),
io_service_(io_service),
work_(io_service),
handler_(handler)
{
}
void operator()()
{
// Check if the operation has been cancelled.
if (impl_.expired())
{
iterator_type iterator;
io_service_.post(boost::asio::detail::bind_handler(handler_,
boost::asio::error::operation_aborted, iterator));
return;
}
// Perform the blocking host resolution operation.
boost::asio::detail::addrinfo_type* address_info = 0;
std::string host_name = query_.host_name();
std::string service_name = query_.service_name();
boost::asio::detail::addrinfo_type hints = query_.hints();
boost::system::error_code ec;
socket_ops::getaddrinfo(host_name.length() ? host_name.c_str() : 0,
service_name.c_str(), &hints, &address_info, ec);
auto_addrinfo auto_address_info(address_info);
// Invoke the handler and pass the result.
iterator_type iterator;
if (!ec)
iterator = iterator_type::create(address_info, host_name, service_name);
io_service_.post(boost::asio::detail::bind_handler(
handler_, ec, iterator));
}
private:
boost::weak_ptr<void> impl_;
query_type query_;
boost::asio::io_service& io_service_;
boost::asio::io_service::work work_;
Handler handler_;
};
// Asynchronously resolve a query to a list of entries.
template <typename Handler>
void async_resolve(implementation_type& impl, const query_type& query,
Handler handler)
{
if (work_io_service_)
{
start_work_thread();
work_io_service_->post(
resolve_query_handler<Handler>(
impl, query, this->get_io_service(), handler));
}
}
// Resolve an endpoint to a list of entries.
iterator_type resolve(implementation_type&,
const endpoint_type& endpoint, boost::system::error_code& ec)
{
// First try resolving with the service name. If that fails try resolving
// but allow the service to be returned as a number.
char host_name[NI_MAXHOST];
char service_name[NI_MAXSERV];
int flags = endpoint.protocol().type() == SOCK_DGRAM ? NI_DGRAM : 0;
socket_ops::getnameinfo(endpoint.data(), endpoint.size(),
host_name, NI_MAXHOST, service_name, NI_MAXSERV, flags, ec);
if (ec)
{
flags |= NI_NUMERICSERV;
socket_ops::getnameinfo(endpoint.data(), endpoint.size(),
host_name, NI_MAXHOST, service_name, NI_MAXSERV, flags, ec);
}
if (ec)
return iterator_type();
return iterator_type::create(endpoint, host_name, service_name);
}
template <typename Handler>
class resolve_endpoint_handler
{
public:
resolve_endpoint_handler(implementation_type impl,
const endpoint_type& endpoint, boost::asio::io_service& io_service,
Handler handler)
: impl_(impl),
endpoint_(endpoint),
io_service_(io_service),
work_(io_service),
handler_(handler)
{
}
void operator()()
{
// Check if the operation has been cancelled.
if (impl_.expired())
{
iterator_type iterator;
io_service_.post(boost::asio::detail::bind_handler(handler_,
boost::asio::error::operation_aborted, iterator));
return;
}
// First try resolving with the service name. If that fails try resolving
// but allow the service to be returned as a number.
char host_name[NI_MAXHOST];
char service_name[NI_MAXSERV];
int flags = endpoint_.protocol().type() == SOCK_DGRAM ? NI_DGRAM : 0;
boost::system::error_code ec;
socket_ops::getnameinfo(endpoint_.data(), endpoint_.size(),
host_name, NI_MAXHOST, service_name, NI_MAXSERV, flags, ec);
if (ec)
{
flags |= NI_NUMERICSERV;
socket_ops::getnameinfo(endpoint_.data(), endpoint_.size(),
host_name, NI_MAXHOST, service_name, NI_MAXSERV, flags, ec);
}
// Invoke the handler and pass the result.
iterator_type iterator;
if (!ec)
iterator = iterator_type::create(endpoint_, host_name, service_name);
io_service_.post(boost::asio::detail::bind_handler(
handler_, ec, iterator));
}
private:
boost::weak_ptr<void> impl_;
endpoint_type endpoint_;
boost::asio::io_service& io_service_;
boost::asio::io_service::work work_;
Handler handler_;
};
// Asynchronously resolve an endpoint to a list of entries.
template <typename Handler>
void async_resolve(implementation_type& impl, const endpoint_type& endpoint,
Handler handler)
{
if (work_io_service_)
{
start_work_thread();
work_io_service_->post(
resolve_endpoint_handler<Handler>(
impl, endpoint, this->get_io_service(), handler));
}
}
private:
// Helper class to run the work io_service in a thread.
class work_io_service_runner
{
public:
work_io_service_runner(boost::asio::io_service& io_service)
: io_service_(io_service) {}
void operator()() { io_service_.run(); }
private:
boost::asio::io_service& io_service_;
};
// Start the work thread if it's not already running.
void start_work_thread()
{
boost::asio::detail::mutex::scoped_lock lock(mutex_);
if (!work_thread_)
{
work_thread_.reset(new boost::asio::detail::thread(
work_io_service_runner(*work_io_service_)));
}
}
// Mutex to protect access to internal data.
boost::asio::detail::mutex mutex_;
// Private io_service used for performing asynchronous host resolution.
boost::scoped_ptr<boost::asio::io_service> work_io_service_;
// Work for the private io_service to perform.
boost::scoped_ptr<boost::asio::io_service::work> work_;
// Thread used for running the work io_service's run loop.
boost::scoped_ptr<boost::asio::detail::thread> work_thread_;
};
} // namespace detail
} // namespace asio
} // namespace boost
#include <boost/asio/detail/pop_options.hpp>
#endif // BOOST_ASIO_DETAIL_RESOLVER_SERVICE_HPP