<html> <head><title>dkim_set_dns_callback()</title></head> <body> <!-- $Id: dkim_set_dns_callback.html,v 1.3 2010/07/24 04:52:15 cm-msk Exp $ --> <h1>dkim_set_dns_callback()</h1> <p align="right"><a href="index.html">[back to index]</a></p> <table border="0" cellspacing=4 cellpadding=4> <!---------- Synopsis -----------> <tr><th valign="top" align=left width=150>SYNOPSIS</th><td> <pre> #include <dkim.h> <a href="dkim_stat.html"><tt>DKIM_STAT</tt></a> dkim_set_dns_callback( <a href="dkim_lib.html"><tt>DKIM_LIB</tt></a> *libopendkim, void (*func)(const void *context), unsigned int interval); ); </pre> Define a function which should be called from time to time while waiting for a DNS response to become available. This is particularly meant for use when libopendkim is being used by an application which is timeout-sensitive where a heartbeat ("still alive, operation in progress") message is desirable. <p> When defined, the specified function will be called at the specified interval even if the DNS response has not yet arrived, using the caller-specific context pointer set by the <a href="dkim_set_user_context.html"><tt>dkim_set_user_context()</tt></a> function (if any) as the parameter to that function. </td></tr> <!----------- Description ----------> <tr><th valign="top" align=left>DESCRIPTION</th><td> <table border="1" cellspacing=1 cellpadding=4> <tr align="left" valign=top> <th width="80">Called When</th> <td><tt>dkim_set_dns_callback()</tt> can called at any time. </td> </tr> </table> <!----------- Arguments ----------> <tr><th valign="top" align=left>ARGUMENTS</th><td> <table border="1" cellspacing=0> <tr bgcolor="#dddddd"><th>Argument</th><th>Description</th></tr> <tr valign="top"><td>libopendkim</td> <td>Library-specific handle, returned by <a href="dkim_init.html"><tt>dkim_init()</tt></a>. </td></tr> <tr valign="top"><td>func</td> <td>A pointer to a function which takes a single void pointer which should be called at the requested interval while waiting for a DNS reply. If NULL, no callback will be used. </td></tr> <tr valign="top"><td>interval</td> <td>Desired interval, in seconds, between calls to <tt>func</tt>. </td></tr> </table> </td></tr> <!----------- Return Values ----------> <tr> <th valign="top" align=left>RETURN VALUES</th> <td> <ul> <li>DKIM_STAT_OK -- the callback and interval were successfully registered <li>DKIM_STAT_NOTIMPLEMENT -- the underlying DNS resolution service does not provide a callback facility </ul> </td> </tr> </table> <hr size="1"> <font size="-1"> Copyright (c) 2007 Sendmail, Inc. and its suppliers. All rights reserved. <br> Copyright (c) 2009, 2010, The OpenDKIM Project. All rights reserved. <br> By using this file, you agree to the terms and conditions set forth in the respective licenses. </font> </body> </html>