grequest.h

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//
// Copyright (C) 2017 Graeme Walker
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// 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 General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
// ===
///
/// \file grequest.h
///

#ifndef G_REQUEST_H
#define G_REQUEST_H

#include "gdef.h"
#include "gnet.h"
#include "gaddress.h"
#include "gwindow.h"

namespace GNet
{
    class Request ;
    class HostRequest ;
    class ServiceRequest ;
}

/// \class GNet::Request
/// A base class for making asynchronous DNS requests under Windows.
/// \see WSAAsyncGetHostByName()
/// 
class GNet::Request
{
protected:
    enum { magic = 968 } ;
    int m_magic ;
    int m_error ;
    HANDLE m_handle ;
    char m_buffer[MAXGETHOSTSTRUCT] ;
    bool m_host ;
    bool m_done ;
    bool m_numeric ;
    GNet::Address m_address ;

protected:
    explicit Request( bool host ) ;
        ///< Constructor. Derived class constructors 
        ///< should issue the appropriate WSAAsync..()
        ///< request, with m_buffer[] given as the
        ///< result buffer.

public:
    virtual ~Request() ;
        ///< Virtual destructor. Cancels any
        ///< outstanding request.

    bool valid() const ;
        ///< Returns true if the constructor
        ///< initiated a request properly.

    std::string reason() const ;
        ///< Returns the failure reason if
        ///< valid() or onMessage() returned
        ///< false.

    bool onMessage( WPARAM wparam , LPARAM lparam ) ;
        ///< To be called when the request has
        ///< been completed. Returns false
        ///< on error.

private:
    Request( const Request & ) ;
    void operator=( const Request & ) ;
    static const char *reason( bool host , int error ) ;
} ;

/// \class GNet::HostRequest
/// A derivation of GNet::Request used for hostname lookup requests.
/// 
class GNet::HostRequest : public Request
{
public:
    HostRequest( std::string host_name , HWND hwnd , unsigned msg ) ;
        ///< Constructor.

    Address result() const ;
        ///< Returns the resolved address with a zero port number.

    std::string fqdn() const ;
        ///< Returns the fully-qualified canonical hostname, if
        ///< available.

private:
    bool numeric( std::string s , Address & address ) ;
    HostRequest( const HostRequest & ) ;
    void operator=( const HostRequest & ) ;
} ;

/// \class GNet::ServiceRequest
/// A derivation of GNet::Request used for service (port) lookup requests.
/// 
class GNet::ServiceRequest : public Request
{
public:
    ServiceRequest( std::string service_name , bool udp , 
        HWND hwnd , unsigned msg ) ;
            ///< Constructor.

    Address result() const ;
        ///< Returns the address with a zeroed host part.

private:
    static const char * protocol( bool udp ) ;
    bool numeric( std::string s , Address & address ) ;
} ;

#endif