vrpn_ForwarderController.h

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#ifndef VRPN_FORWARDER_CONTROLLER_H
#define VRPN_FORWARDER_CONTROLLER_H
 
#include "vrpn_Configure.h" // for VRPN_API, VRPN_CALLBACK
#include "vrpn_Types.h"     // for vrpn_int32
// vrpn_Forwarder_Controller
//
// Tom Hudson, September 1998
 
// Written to allow remote a client to tell a server to open another port
// and forward some messages on it to a friend of the client's.
 
// Any server that wishes to implement this needs only construct a
// vrpn_Forwarder_Server for each server connection it has open and
// to call the vrpn_Forwarder_Server mainloop frequently.
 
// Clients can construct a vrpn_Forwarder_Controller on a connection
// and call start_remote_forwarding(port) to tell the server to open
// <port>, then call forward_message_type(port, name) to start forwarding
// messages of the given name.
 
// This isn't an ideal solution, because it means clients need access to
// the names of the message, which they are normally insulated from.
 
// Some of the fancier options of the Forwarder (renaming services or
// types, changing class of service) are hidden from the user;  this
// is meant to be a simple interface and simple first implementation.
 
// New Forwarder_Servers are NOT constructed on connections that a
// Forwarder_Server opens, so clients that are only listening to a
// forwarded stream cannot open new forwarders for still other clients to
// listen to.
 
class VRPN_API vrpn_ConnectionForwarder;
class VRPN_API vrpn_Connection;
struct vrpn_HANDLERPARAM;
 
class VRPN_API vrpn_Forwarder_Brain {
 
public:
    vrpn_Forwarder_Brain(vrpn_Connection *);
    virtual ~vrpn_Forwarder_Brain(void);
 
    // Tell a Forwarder_Server to open a vrpn_Connection on remote_port.
 
    virtual vrpn_bool start_remote_forwarding(vrpn_int32 remote_port) = 0;
 
    // Tell a Forwarder_Server to begin forwarding messages of type
    // message_type from the sender named service_name over remote_port.
 
    virtual void forward_message_type(vrpn_int32 remote_port,
                                      const char *service_name,
                                      const char *message_type) = 0;
 
protected:
    vrpn_Connection *d_connection;
 
    vrpn_int32 d_myId;
 
    vrpn_int32 d_start_forwarding_type;
    vrpn_int32 d_forward_type;
 
    static char *encode_start_remote_forwarding(vrpn_int32 *length,
                                                vrpn_int32 remote_port);
    static char *encode_forward_message_type(vrpn_int32 *length,
                                             vrpn_int32 remote_port,
                                             const char *service_name,
                                             const char *message_type);
 
    static void decode_start_remote_forwarding(const char *buffer,
                                               vrpn_int32 *remote_port);
    static void decode_forward_message_type(const char *buffer,
                                            vrpn_int32 *remote_port,
                                            char **service_name,
                                            char **message_type);
};
 
// Server class
 
// VRPN server builders who want to enable remotely-controlled forwarding in
// their server need only create a Forwarder_Server on their server Connections
// and call its mainloop() regularly.
 
struct vrpn_Forwarder_List {
    vrpn_Forwarder_List *next;
    vrpn_int32 port;
    vrpn_Connection *connection;
    vrpn_ConnectionForwarder *forwarder;
};
 
class VRPN_API vrpn_Forwarder_Server : public vrpn_Forwarder_Brain {
 
public:
    vrpn_Forwarder_Server(vrpn_Connection *);
    virtual ~vrpn_Forwarder_Server(void);
 
    virtual void mainloop(void);
 
    virtual vrpn_bool start_remote_forwarding(vrpn_int32 remote_port);
 
    virtual void forward_message_type(vrpn_int32 remote_port,
                                      const char *service_name,
                                      const char *message_type);
 
protected:
    vrpn_Forwarder_List *d_myForwarders;
 
private:
    static int VRPN_CALLBACK handle_start(void *, vrpn_HANDLERPARAM);
    static int VRPN_CALLBACK handle_forward(void *, vrpn_HANDLERPARAM);
};
 
// Client class
 
// Construct a Forwarder_Controller on a connection to control a
// Forwarder_Server on its far end.
 
class VRPN_API vrpn_Forwarder_Controller : public vrpn_Forwarder_Brain {
 
public:
    vrpn_Forwarder_Controller(vrpn_Connection *);
    ~vrpn_Forwarder_Controller(void);
 
    virtual vrpn_bool start_remote_forwarding(vrpn_int32 remote_port);
 
    virtual void forward_message_type(vrpn_int32 remote_port,
                                      const char *service_name,
                                      const char *message_type);
};
 
#endif // VRPN_FORWARDER_CONTROLLER_H