state.c

Design Pattern C Source Code

/*
*/

/*
*/
class TCPOctetStream;
class TCPState;

class TCPConnection {
public:
    TCPConnection();
/*
*/
    void ActiveOpen();
    void PassiveOpen();
    void Close();
/*
*/
    void Send();
    void Acknowledge();
    void Synchronize();
/*
*/
    void ProcessOctet(TCPOctetStream*);
private:
    friend class TCPState;
    void ChangeState(TCPState*);
private:
    TCPState* _state;
};
/*
*/
class TCPState {
public:
    virtual void Transmit(TCPConnection*, TCPOctetStream*);
    virtual void ActiveOpen(TCPConnection*);
    virtual void PassiveOpen(TCPConnection*);
    virtual void Close(TCPConnection*);
    virtual void Synchronize(TCPConnection*);
    virtual void Acknowledge(TCPConnection*);
    virtual void Send(TCPConnection*);
protected:
    void ChangeState(TCPConnection*, TCPState*);
};
/*
*/
#include "TCPClosed.C"
/*
*/
TCPConnection::TCPConnection () {
    _state = TCPClosed::Instance();
}
/*
*/
void TCPConnection::ChangeState (TCPState* s) {
    _state = s;
}
/*
*/
void TCPConnection::ActiveOpen () {
    _state->ActiveOpen(this);
}
/*
*/
void TCPConnection::PassiveOpen () {
    _state->PassiveOpen(this);
}
/*
*/
void TCPConnection::Close () {
    _state->Close(this);
}
/*
*/
void TCPConnection::Acknowledge () {
    _state->Acknowledge(this);
}
/*
*/
void TCPConnection::Synchronize () {
    _state->Synchronize(this);
}
/*
*/
void TCPState::Transmit (TCPConnection*, TCPOctetStream*) { }
void TCPState::ActiveOpen (TCPConnection*) { }
void TCPState::PassiveOpen (TCPConnection*) { }
void TCPState::Close (TCPConnection*) { }
void TCPState::Synchronize (TCPConnection*) { }
/*
*/
void TCPState::ChangeState (TCPConnection* t, TCPState* s) {
    t->ChangeState(s);
}
/*
*/
class TCPEstablished : public TCPState {
public:
    static TCPState* Instance();

    virtual void Transmit(TCPConnection*, TCPOctetStream*);
    virtual void Close(TCPConnection*);
};
/*
*/
class TCPListen : public TCPState {
public:
    static TCPState* Instance();

    virtual void Send(TCPConnection*);
    // ...
};
/*
*/
void TCPClosed::ActiveOpen (TCPConnection* t) {
    // send SYN, receive SYN, ACK, etc.

    ChangeState(t, TCPEstablished::Instance());
}
/*
*/
void TCPClosed::PassiveOpen (TCPConnection* t) {
    ChangeState(t, TCPListen::Instance());
}
/*
*/
void TCPEstablished::Close (TCPConnection* t) {
    // send FIN, receive ACK of FIN

    ChangeState(t, TCPListen::Instance());
}
/*
*/
void TCPEstablished::Transmit (
    TCPConnection* t, TCPOctetStream* o
) {
    t->ProcessOctet(o);
}
/*
*/
void TCPListen::Send (TCPConnection* t) {
    // send SYN, receive SYN, ACK, etc.

    ChangeState(t, TCPEstablished::Instance());
}
/*
*/