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Solstice X.25 9.2 Developer's Guide

6.4.14 N_Xcanlis--Listen Cancel Command/Response

Synopsis
#include <stream.h>
 #include <netx25/x25_proto.h >

 struct strbuf ctlb;

 struct xcanlisf canlis;
 .
 .
 .
 ctlb.len = sizeof(struct xcanlisf);
 ctlb.buf = (char *)canlis;

 putmsg(x25_fd, &ctlb, NULL, 0);
Description

N_Xcanlis is used to cancel an interest in incoming calls.

When used with putmsg, N_Xcanlis is a Listen Cancel Command, when used with getmsg, it is a Listen Cancel Response. Example 6-1 shows how a getmsg can be constructed. The control part of the Listen Command or Response is defined by the xcanlisf structure. There is no data part.

Note -

The Cancel Request removes all listen addresses from the stream. There is no way of cancelling a Listen on a particular address, for example, when the use of the stream is about to be changed by the application.

The control part of a Listen Cancel Command or Response message has a format defined in the xcanlisf structure: 

struct xcanlisf {
 	unsigned char xl_type; /* Always XL_CTL  */
 	unsigned char xl_command; /* Always N_Xcanlis */
 	int c_result; /* Result flag */
 };

This structure has the following member:

Table 6-15 Listen Cancel Command/Response Parameters

Member 

Description 

c_result

A non-zero value of the c_result flag indicates failure of the operation to cancel a Listen. This may indicate that the Listen was not present or that some connect event is outstanding. The closure of a stream on which there is a Listen also cancels the Listen, but in the case of the cancel command message, the stream remains open.