protected Int64 GetNewDelay(TSIP_Response response)
{
Int64 expires = mExpires;
Int64 newdelay = expires; /* default value */
TSIP_Header hdr;
int i;
/*== NOTIFY with subscription-state header with expires parameter */
if (response.CSeq.RequestType == TSIP_Message.tsip_request_type_t.NOTIFY)
{
TSIP_HeaderSubscriptionState hdr_state = response.GetHeader(TSIP_Header.tsip_header_type_t.Subscription_State) as TSIP_HeaderSubscriptionState;
if (hdr_state != null && hdr_state.Expires > 0)
{
expires = TSK_Time.Seconds2Milliseconds(hdr_state.Expires);
goto compute;
}
}
/*== Expires header */
if ((hdr = response.GetHeader(TSIP_Header.tsip_header_type_t.Expires)) != null)
{
expires = TSK_Time.Seconds2Milliseconds((hdr as TSIP_HeaderExpires).DeltaSeconds);
goto compute;
}
/*== Contact header */
for (i = 0; (hdr = response.GetHeaderAtIndex(TSIP_Header.tsip_header_type_t.Contact, i)) != null; i++)
{
TSIP_HeaderContact contact = hdr as TSIP_HeaderContact;
if (contact != null && contact.Uri != null)
{
String transport = TSK_Param.GetValueByName(contact.Uri.Params, "transport");
TSIP_Uri contactUri = this.Stack.GetContactUri(String.IsNullOrEmpty(transport) ? "udp" : transport);
if (contactUri != null)
{
if (String.Equals(contact.Uri.UserName, contactUri.UserName) &&
String.Equals(contact.Uri.Host, contactUri.Host) &&
contact.Uri.Port == contactUri.Port)
{
if (contact.Expires >= 0) /* No expires parameter ==> -1*/
{
expires = TSK_Time.Seconds2Milliseconds(contact.Expires);
goto compute;
}
}
}
}
}
/*
* 3GPP TS 24.229 -
*
* The UE shall reregister the public user identity either 600 seconds before the expiration time if the initial
* registration was for greater than 1200 seconds, or when half of the time has expired if the initial registration
* was for 1200 seconds or less.
*/
compute:
expires = TSK_Time.Milliseconds2Seconds(expires);
newdelay = (expires > 1200) ? (expires - 600) : (expires / 2);
return(TSK_Time.Seconds2Milliseconds(newdelay));
}
