user_rapi_callback()

The user_rapi_callback() call provides the RSVP callback function.

Syntax

       #include <rsvprapi.h>

int  _System user_rapi_callback(
       rapi_sid_t         sid,
       rapi_eventinfo_t   eventType,
       rapi_styleid_t     styleID,
       int                errorCode,
       int                errorValue,
       struct sockaddr   *pErrorNodeAddr,
       u_char             errorFlags,
       int                nFilterSpecs,
       rapi_filter_t     *pFilterSpec,
       int                nFlowSpecs,
       rapi_flowspec_t   *pFlowSpec,
       int                nAdSpecs,
       rapi_adspec_t     *pAdSpec,
       void              *pClientArg);

Parameters

sid

Session identifier of the session that generated the event. eventType

RAPI_PATH_EVENT

A path event is generated by a rapi_sender() call for the session. This can be received by a program that has called rapi_session(). A non-zero value of nFlowSpecs indicates that a path exists from a sender to a potential receiver. A zero value of nFlowSpecs indicates that a previous path may have gone away.

A reservation event is generated by a rapi_reserve() call for the session. This is received by a sender to which the reservation applies. A zero value of nFlowSpecs indicates that a previous reservation may have gone away.

There has been an error associated with the path event. See errorCode for the type of error.

There has been an error associated with the reservation event. See errorCode for the type of error.

When a rapi_reserve() call specifies that confirmation of the reservation is requested, this event can be generated to confirm (with a very high probability) that the reservation has been made from receiver to sender.

styleID

Reservation style. This is non-zero only for RAPI_RESV_EVENT and RAPI_RESV_ERROR.

errorCode

Type of error that occurred, for a RAPI_PATH_ERROR or RAPI_RESV_ERROR event.

errorValue

Extra error value for a RAPI_PATH_ERROR or RAPI_RESV_ERROR event. This parameter is used if it is necessary for RSVP to report an extra error. An example might be an "errno" value.

pErrorNodeAddr

A pointer to the IP address and port of the node that detected an error. For this implementation, this is a pointer to a sockaddr_in structure. This is set only for a RAPI_PATH_ERROR or RAPI_RESV_ERROR event.

errorFlags

Error flag for a RAPI_PATH_ERROR event. Set to one of these values:

RAPI_ERRF_InPlace

This value indicates that the reservation failed, but another probably smaller reservation was left in place at the failing node address.

This value indicates that the flowspec that was requested by this receiver was not the cause of the error, even though the reservation failed. Presumably the failure was due to a larger reservation that this one was merged with.

nFilterSpecs

The number of filterspecs or sender templates pointed to by pFilterSpec.

pFilterSpec

A pointer to an array of filterspecs or sender templates, or NULL.

nFlowSpecs

The number of flowspecs or tspecs pointed to by pFlowSpec.

pFlowSpec

A pointer to an array of flowspecs or tspecs, or NULL.

nAdSpecs

The number of adspecs pointed to by pAdSpec.

pAdSpec

A pointer to an array of adspecs, or NULL.

pClientArg

The client-supplied argument that was provided when rapi_session() was called.

Description

The user_rapi_callback() call processes asynchronous events from the RSVP API. A pointer to the function is passed to rapi_session(). The callback function must be declared as shown above. The name of the function is chosen by the user, but is shown above as user_rapi_callback().

The rapi_getfd() call returns a socket for the session. The socket may be used with the select() call as a read socket. When a select() call indicates that there is some data to read, a rapi_dispatch() call should be issued to read and process the data from the socket. Typically the rapi_dispatch() call will invoke the user callback function to provide the program with information, if the user supplied such a function in the rapi_session() call.

The user callback function should copy any information that it wants to save, because the storage that is pointed to by the pErrorNodeAddr, pFilterSpec, pFlowSpec, and pAdSpec will be freed as soon as the callback function returns.

Return Values

The function is declared to have an integer return value, but nothing is done with the value currently. It is recommended that the user always return 0.

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