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chan_pjsip: Race between channel answer and bridge setup when using direct media

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When direct media is enabled and a pjsip channel is answered a race would occur
between the handling of the answer and bridge setup. Sometimes the media
negotiation would take place after the native bridge was setup. This resulted
in a NULL media address, which in turn resulted in Asterisk using its address
as the remote media address when sending a reinvite.  This patch makes the
chan_pjsip answer handler synchronous thus alleviating the race condition (the
bridge won't start setting things up until after it returns).

ASTERISK-24563 #close
Reported by: Steve Pitts
Review: https://reviewboard.asterisk.org/r/4257/
........

Merged revisions 429477 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@429478 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Kevin Harwell
2014-12-12 15:31:38 +00:00
parent 2e6d2b1484
commit 72499dc697
1 changed files with 11 additions and 6 deletions
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17
channels/chan_pjsip.c
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@@ -490,7 +490,6 @@ static int answer(void *data)
struct ast_sip_session *session = data;
if (session->inv_session->state == PJSIP_INV_STATE_DISCONNECTED) {
ao2_ref(session, -1);
return 0;
}
@@ -507,8 +506,6 @@ static int answer(void *data)
ast_sip_session_send_response(session, packet);
}
ao2_ref(session, -1);
return (status == PJ_SUCCESS) ? 0 : -1;
}
@@ -516,19 +513,27 @@ static int answer(void *data)
static int chan_pjsip_answer(struct ast_channel *ast)
{
struct ast_sip_channel_pvt *channel = ast_channel_tech_pvt(ast);
struct ast_sip_session *session;
if (ast_channel_state(ast) == AST_STATE_UP) {
return 0;
}
ast_setstate(ast, AST_STATE_UP);
session = ao2_bump(channel->session);
ao2_ref(channel->session, +1);
if (ast_sip_push_task(channel->session->serializer, answer, channel->session)) {
/* the answer task needs to be pushed synchronously otherwise a race condition
can occur between this thread and bridging (specifically when native bridging
attempts to do direct media) */
ast_channel_unlock(ast);
if (ast_sip_push_task_synchronous(session->serializer, answer, session)) {
ast_log(LOG_WARNING, "Unable to push answer task to the threadpool. Cannot answer call\n");
ao2_cleanup(channel->session);
ao2_ref(session, -1);
ast_channel_lock(ast);
return -1;
}
ao2_ref(session, -1);
ast_channel_lock(ast);
return 0;
}