Assertion and possibly crash in ICE stream transport when client is not behind NAT (thanks Nicolas Fauvel for the report)

[bennylp]

Symptom:

When pjsua is run with ICE, STUN, and TURN, and pjsua is not behind NAT, the following assertion will be triggered when making a call:

On v0.9:

  ./src/pjnath/ice_strans.c:826: pj_ice_strans_get_def_cand: Assertion 
`comp->default_cand>=0 && comp->default_cand<comp->cand_cnt' failed.

On v1.0-rc1 (only the line number is different):

  ./src/pjnath/ice_strans.c:853: pj_ice_strans_get_def_cand: Assertion 
`comp->default_cand>=0 && comp->default_cand<comp->cand_cnt' failed.

How to reproduce:

This can be reproduced by using the following pjsua command-line arguments:

--use-ice --use-turn --stun-srv=192.168.0.2 --turn-srv=192.168.0.2:34780 \
--turn-user=100 --turn-passwd=100

Note that the STUN server is on the same LAN as the client.

Description:

When ICE stream transport (ice_strans)is initialized, it selects a default candidate to be used as the primary address in the SDP. The default candidate is TURN candidate if TURN is used.

During the address resolution process, the STUN candidate will be removed from the candidate list if the mapped address matches one of the host addresses (i.e. when the client is not behind NAT). This process is called pruning in pjnath.

Unfortunately, the default candidate index is not updated when a candidate is removed, hence the assertion.

[bennylp]

Fixed in r2258