scoped_asio_stream.hpp

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//    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- OpenVPN Inc.
//
//    SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
 
// A scoped Asio stream that is automatically closed by its destructor.
 
#ifndef OPENVPN_ASIO_SCOPED_ASIO_STREAM_H
#define OPENVPN_ASIO_SCOPED_ASIO_STREAM_H
 
#include <openvpn/common/size.hpp>
 
namespace openvpn {
 
template <typename STREAM>
class ScopedAsioStream
{
    ScopedAsioStream(const ScopedAsioStream &) = delete;
    ScopedAsioStream &operator=(const ScopedAsioStream &) = delete;
 
  public:
    typedef STREAM *base_type;
 
    ScopedAsioStream()
        : obj_(undefined())
    {
    }
 
    explicit ScopedAsioStream(STREAM *obj)
        : obj_(obj)
    {
    }
 
    static STREAM *undefined()
    {
        return nullptr;
    }
 
    STREAM *release()
    {
        STREAM *ret = obj_;
        obj_ = nullptr;
        // OPENVPN_LOG("**** SAS RELEASE=" << ret);
        return ret;
    }
 
    static bool defined_static(STREAM *obj)
    {
        return obj != nullptr;
    }
 
    bool defined() const
    {
        return defined_static(obj_);
    }
 
    STREAM *operator()() const
    {
        return obj_;
    }
 
    void reset(STREAM *obj)
    {
        close();
        obj_ = obj;
        // OPENVPN_LOG("**** SAS RESET=" << obj_);
    }
 
    // unusual semantics: replace obj without closing it first
    void replace(STREAM *obj)
    {
        // OPENVPN_LOG("**** SAS REPLACE " << obj_ << " -> " << obj);
        obj_ = obj;
    }
 
    // return false if close error
    bool close()
    {
        if (defined())
        {
            // OPENVPN_LOG("**** SAS CLOSE obj=" << obj_);
            delete obj_;
            obj_ = nullptr;
        }
        return true;
    }
 
    ~ScopedAsioStream()
    {
        // OPENVPN_LOG("**** SAS DESTRUCTOR");
        close();
    }
 
  private:
    STREAM *obj_;
};
 
} // namespace openvpn
 
#endif