[asterisk-bugs] [JIRA] (ASTERISK-29276) stun: Implementation causes delay and does not work in all network topologies.

[Chris (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-29276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=253775#comment-253775 ] 

Chris commented on ASTERISK-29276:
----------------------------------

Update about field-usage:  If the installation is without Internet connection all *local LAN calls* are also delayed with 3 seconds.


> stun: Implementation causes delay and does not work in all network topologies.
> ------------------------------------------------------------------------------
>
>                 Key: ASTERISK-29276
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-29276
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_rtp_asterisk
>    Affects Versions: 16.16.0
>            Reporter: Chris
>            Severity: Major
>
> Despite of the documentation here https://wiki.asterisk.org/wiki/display/~jcolp/ICE,+STUN,+and+TURN+Support Asterisk does *not* implement this RFC rfc5389. Id rather implements RFC https://tools.ietf.org/html/rfc3489 which is known for it's design flaws.
> {quote}
> However, experience since the publication
>    of RFC 3489 has found that classic STUN simply does not work
>    sufficiently well to be a deployable solution.  The address and port
>    learned through classic STUN are sometimes usable for communications
>    with a peer, and sometimes not.  Classic STUN provided no way to
>    discover whether it would, in fact, work or not, and it provided no
>    remedy in cases where it did not.  Furthermore, classic STUN's
>    algorithm for classification of NAT types was found to be faulty, as
>    many NATs did not fit cleanly into the types defined there.
> {quote}
> The current rfc3489 implementation in stun.c also has serious flaws. E.g. it always waits for 3 seconds before doing a retry. 
> This means, if the UDP packet is dropped, you immediately have a delay of 3 seconds before the call starts.
> {quote}
> 	/* Wait for response. */
> 		{
> 			struct pollfd pfds = { .fd = s, .events = POLLIN };
> 			int ms;
> 			//** Reduce to < 200MS
> 			ms = ast_remaining_ms(start, 3000);
> 			if (ms <= 0) {
> 				/* No response, timeout */
> 				res = 1;
> 				continue;
> 			}
> 			res = ast_poll(&pfds, 1, ms);
> 			if (res < 0) {
> 				/* Error */
> 				continue;
> 			}
> 			if (!res) {
> 				/* No response, timeout */
> 				res = 1;
> 				continue;
> 			}
> 		}
> {quote}
> What should be improved :
> - Implement RFC rfc5389 or use 3rd party STUN library (pjsip ?)
> - Improve wait-loop in stun.c 
> - Update the docs reflecting correct RFC



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