DC_PLUG_NEW

Section: distcache (2)
Updated: 2004.03.23
Index Return to Main Contents

NAME

DC_PLUG_new, DC_PLUG_free, DC_PLUG_to_select, DC_PLUG_io - basic DC_PLUG functions

SYNOPSIS

 #include <distcache/dc_plug.h>

 DC_PLUG *DC_PLUG_new(NAL_CONNECTION *conn, unsigned int flags);
 int DC_PLUG_free(DC_PLUG *plug);
 void DC_PLUG_to_select(DC_PLUG *plug, NAL_SELECTOR *sel);
 int DC_PLUG_io(DC_PLUG *plug, NAL_SELECTOR *sel);

DESCRIPTION

DC_PLUG_new() allocates and initialises a DC_PLUG structure encapsulating the specified connection. The flags parameter is zero or a bitmask combining one or more of the following flags;

 #define DC_PLUG_FLAG_TO_SERVER         (unsigned int)0x0001
 #define DC_PLUG_FLAG_NOFREE_CONN       (unsigned int)0x0002

If the DC_PLUG_FLAG_TO_SERVER flag is specified, the plug object will expect to be sending ``request'' messages and receiving ``response'' messages, otherwise will default to the opposite sense.

DC_PLUG_free() frees the DC_PLUG structure and, unless it had been created with the DC_PLUG_FLAG_NOFREE_CONN flag, will also destroy the connection object it encapsulates.

DC_PLUG_to_select() is used to add a plug object to the sel selector so that it can be tested for network events it is waiting on. This will automatically handle selection of flags depending on the plug object's state. Ie. it will select for writability on its underlying connection only if there is data waiting to be sent, and likewise will select for readability only if it is ready to receive any data that may have arrived.

DC_PLUG_io() is used to allow network I/O to be performed on a plug object's underlying connection depending on the results of the last select operation on sel.

RETURN VALUES

DC_PLUG_new() returns the new plug object on success, otherwise NULL for failure.

DC_PLUG_free() should never fail and should only return non-zero results.

DC_PLUG_to_select() has no return value.

DC_PLUG_io() return zero on an error, otherwise non-zero.

None of the DC_PLUG functions sets (or clears) errno because it is implemented on top of the libnal library which in turn is an abstraction layer for the system's networking interfaces. As such, any errno codes set by failure in system libraries will not be overwritten by these functions.

AUTHOR

This toolkit was designed and implemented by Geoff Thorpe for Cryptographic Appliances Incorporated. Since the project was released into open source, it has a home page and a project environment where development, mailing lists, and releases are organised. For problems with the software or this man page please check for new releases at the project web-site below, mail the users mailing list described there, or contact the author at geoff@geoffthorpe.net.