Assertion due to deleted account during incoming call in PJSUA2

[nanangizz]

Reported that assertion occurs in incoming call callback due to the selected account is being deleted:

../src/pjsua-lib/pjsua_acc.c:650: void *pjsua_acc_get_user_data(pjsua_acc_id): assertion "pjsua_var.acc[acc_id].valid" failed

pjsua_acc_get_user_data+280
pj::Account::lookup(int)+20
pj::Endpoint::lookupAcc(int, char const*)+24
pj::Endpoint::on_incoming_call(int, int, pjsip_rx_data*)+60)
pjsua_call_on_incoming+6336

Initially this sounds strange as pjsua_call_on_incoming() and pjsua_acc_del() seem to be mutually exclusive, i.e: protected by PJSUA lock. However, after investigation, it is possible because pjsua_call_on_state_changed() may temporarily release the PJSUA lock. In PJSUA2 (not the case in PJSUA), the pjsua_call_on_state_changed() will be called when a 100/Trying response is sent and the incoming call callback is called early (before media transport creation callback and before sending 100 response).

The assertion seems to occur when PJSUA invokes incoming call callback (after sending 100 response or pjsua_call_on_state_changed()) which eventually will be ignored by PJSUA2 as such callback has been called earlier, so the proposed solution here is to avoid invoking the PJSUA callback when PJSUA2 has invoke the incoming call callback earlier.

Thanks to Valery Kolesnikov for the report.

[anikitin-intermedia]

Could it impact somehow on pjsua interface callbacks?

[nanangizz]

It should not. The call->incoming_data is only released & set to NULL after invoking incoming call callback.

[sauwming]

on_create_media_transport()?

Perhaps also fix L#2144 above: https://github.com/pjsip/pjproject/pull/4024/files#diff-38326e41666262ac676da6de5d00a2f2ef0741b5ed851d1f1fae46aded951bf1L2144