[asterisk-bugs] [JIRA] (ASTERISK-24374) "sip qualify peer" CLI command stops periodic pokes for the peer forever, if the peer is unreachable

[Joshua Colp (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-24374?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Joshua Colp updated ASTERISK-24374:
-----------------------------------

    Affects Version/s: 13.18.4

> "sip qualify peer" CLI command stops periodic pokes for the peer forever, if the peer is unreachable
> ----------------------------------------------------------------------------------------------------
>
>                 Key: ASTERISK-24374
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-24374
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Channels/chan_sip/General
>    Affects Versions: 1.8.31.0, 13.18.4
>            Reporter: Michele Cicciotti (PrivateWave SpA)
>            Severity: Minor
>
> Periodic pokes for a realtime peer are started by the first call to {{sip_poke_peer}}. {{sip_poke_peer}} cancels the current {{pokeexpire}} timer, and transmits an {{OPTION}} request to the peer. If the transmission fails, {{sip_poke_noanswer}} is called immediately; otherwise, the {{pokeexpire}} timer is set to call {{sip_poke_noanswer}} after {{maxms * 2}} milliseconds (the maximum allowed roundtrip time)
> If the peer answers to the {{OPTION}} request, {{handle_response_peerpoke}} is called, which updates peer reachability and re-schedules the pokeexpire timer to call {{sip_poke_peer_s}} in {{qualifyfreq}} milliseconds (if the peer is reachable) or 10 seconds
> If the peer fails to answer, {{sip_poke_noanswer}} is called by the scheduler. {{sip_poke_noanswer}} sets the peer as unreachable, and schedules the {{pokeexpire}} timer to call {{sip_poke_peer_s}} in 10 seconds
> {{sip_poke_peer_s}} is little more than a wrapper to {{sip_poke_peer}}
> To sum up, the periodic poke loop goes like: {{sip_poke_peer}} → {{sip_poke_noanswer}}/{{handle_response_peerpoke}} → {{sip_poke_peer_s}} → repeat
> However, when {{sip_poke_peer}} is called by CLI/manager command {{sip qualify peer}}, it won't schedule a call to {{sip_poke_noanswer}}:
> {code}
> 	} else if (!force) {
> 		AST_SCHED_REPLACE_UNREF(peer->pokeexpire, sched, peer->maxms * 2, sip_poke_noanswer, peer,
> 				unref_peer(_data, "removing poke peer ref"),
> 				unref_peer(peer, "removing poke peer ref"),
> 				ref_peer(peer, "adding poke peer ref"));
> 	}
> {code}
> If the peer is unreachable, {{handle_response_peerpoke}} will never be called. This deadlock is supposed to be broken by {{sip_poke_noanswer}}, but it's never scheduled (and not all network errors can be detected synchronously by {{transmit_invite}}, so {{sip_poke_noanswer}} may never be called directly, either). Nobody is left to schedule a call to {{sip_poke_peer_s}}: the periodic poke state machine is dead and there is no way to restart it, except by pruning the peer from the realtime table
> The easiest way to fix the issue is probably to change the above code into:
> \[Edit\]: *Inline patch removed by mjordan*



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