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// Copyright (C) 2010-2017 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#ifndef IO_SOCKET_H
#define IO_SOCKET_H 1
// IMPORTANT NOTE: only very few ASIO headers files can be included in
// this file. In particular, asio.hpp should never be included here.
// See the description of the namespace below.
#include <unistd.h> // for some network system calls
#include <functional>
#include <string>
#include <exceptions/exceptions.h>
namespace isc {
namespace asiolink {
/// \brief The \c IOSocket class is an abstract base class to represent
/// various types of network sockets.
///
/// This class is a wrapper for the ASIO socket classes such as
/// \c ip::tcp::socket and \c ip::udp::socket.
///
/// Derived class implementations are completely hidden within the
/// implementation. User applications only get access to concrete
/// \c IOSocket objects via the abstract interfaces.
///
/// We may revisit this decision when we generalize the wrapper and more
/// modules use it. Also, at that point we may define a separate (visible)
/// derived class for testing purposes rather than providing factory methods
/// (i.e., getDummy variants below).
class IOSocket {
public:
/// @name Types of objects encapsulating socket options.
//@{
/// @brief Represents SO_REUSEADDR socket option.
typedef boost::asio::socket_base::reuse_address ReuseAddress;
//@}
///
/// \name Constructors and Destructor
///
/// Note: The copy constructor and the assignment operator are
/// intentionally defined as private, making this class non-copyable.
//@{
private:
IOSocket(const IOSocket& source);
IOSocket& operator=(const IOSocket& source);
protected:
/// \brief The default constructor.
///
/// This is intentionally defined as \c protected as this base class
/// should never be instantiated (except as part of a derived class).
IOSocket() {}
public:
/// The destructor.
virtual ~IOSocket() {}
//@}
/// \brief Return the "native" representation of the socket.
///
/// In practice, this is the file descriptor of the socket for
/// UNIX-like systems so the current implementation simply uses
/// \c int as the type of the return value.
/// We may have to need revisit this decision later.
///
/// In general, the application should avoid using this method;
/// it essentially discloses an implementation specific "handle" that
/// can change the internal state of the socket (consider the
/// application closes it, for example).
/// But we sometimes need to perform very low-level operations that
/// requires the native representation. Passing the file descriptor
/// to a different process is one example.
/// This method is provided as a necessary evil for such limited purposes.
///
/// This method never throws an exception.
///
/// \return The native representation of the socket. This is the socket
/// file descriptor for UNIX-like systems.
virtual int getNative() const = 0;
/// \brief Return the transport protocol of the socket.
///
/// Currently, it returns \c IPPROTO_UDP for UDP sockets, and
/// \c IPPROTO_TCP for TCP sockets.
///
/// This method never throws an exception.
///
/// \return IPPROTO_UDP for UDP sockets
/// \return IPPROTO_TCP for TCP sockets
virtual int getProtocol() const = 0;
/// \brief Return a non-usable "dummy" UDP socket for testing.
///
/// This is a class method that returns a "mock" of UDP socket.
/// This is not associated with any actual socket, and its only
/// responsibility is to return \c IPPROTO_UDP from \c getProtocol().
/// The only feasible usage of this socket is for testing so that
/// the test code can prepare some "UDP data" even without opening any
/// actual socket.
///
/// This method never throws an exception.
///
/// \return A reference to an \c IOSocket object whose \c getProtocol()
/// returns \c IPPROTO_UDP.
static IOSocket& getDummyUDPSocket();
/// \brief Return a non-usable "dummy" TCP socket for testing.
///
/// See \c getDummyUDPSocket(). This method is its TCP version.
///
/// \return A reference to an \c IOSocket object whose \c getProtocol()
/// returns \c IPPROTO_TCP.
static IOSocket& getDummyTCPSocket();
};
} // namespace asiolink
} // namespace isc
#endif // IO_SOCKET_H
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