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Add some missing locking in chan_sip.

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This patch adds some missing locking to the function 
send_provisional_keepalive_full().  This function is called from the scheduler,
which is processed in the SIP monitor thread.  The associated channel (or pbx)
thread will also be using the same sip_pvt and ast_channel so locking must be
used.  The sip_pvt_lock_full() function is used to ensure proper locking order
in a safe manner.

In passing, document a suspected reference counting error in this function.
The "fix" is left commented out because when the "fix" is present, crashes
occur.  My theory is that fixing it is exposing a reference counting error
elsewhere, but I don't know where.  (Or my analysis of this being a problem
could have been completely wrong in the first place).  Leave the comment in
the code for so that someone may investigate it again in the future.

Also add a bit of doxygen to transmit_provisional_response().

(closes issue ASTERISK-18979)

Review: https://reviewboard.asterisk.org/r/1648


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@351182 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Russell Bryant
2012-01-17 01:37:03 +00:00
parent d310ccf250
commit afcb666f2e
1 changed files with 38 additions and 3 deletions
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41
channels/chan_sip.c
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@@ -4074,6 +4074,10 @@ static void add_blank(struct sip_request *req)
static int send_provisional_keepalive_full(struct sip_pvt *pvt, int with_sdp)
{
const char *msg = NULL;
struct ast_channel *chan;
int res = 0;
chan = sip_pvt_lock_full(pvt);
if (!pvt->last_provisional || !strncasecmp(pvt->last_provisional, "100", 3)) {
msg = "183 Session Progress";
@@ -4085,10 +4089,35 @@ static int send_provisional_keepalive_full(struct sip_pvt *pvt, int with_sdp)
} else {
transmit_response(pvt, S_OR(msg, pvt->last_provisional), &pvt->initreq);
}
return PROVIS_KEEPALIVE_TIMEOUT;
res = PROVIS_KEEPALIVE_TIMEOUT;
}
return 0;
if (chan) {
ast_channel_unlock(chan);
chan = ast_channel_unref(chan);
}
if (!res) {
pvt->provisional_keepalive_sched_id = -1;
}
sip_pvt_unlock(pvt);
#if 0
/*
* XXX BUG TODO
*
* Without this code, it appears as if this function is leaking its
* reference to the sip_pvt. However, adding it introduces a crash.
* This points to some sort of reference count imbalance elsewhere,
* but I'm not sure where ...
*/
if (!res) {
dialog_unref(pvt, "dialog ref for provisional keepalive");
}
#endif
return res;
}
static int send_provisional_keepalive(const void *data) {
@@ -10681,7 +10710,13 @@ static void get_realm(struct sip_pvt *p, const struct sip_request *req)
ast_string_field_set(p, realm, sip_cfg.realm);
}
/* Only use a static string for the msg, here! */
/*!
* \internal
*
* \arg msg Only use a string constant for the msg, here, it is shallow copied
*
* \note assumes the sip_pvt is locked.
*/
static int transmit_provisional_response(struct sip_pvt *p, const char *msg, const struct sip_request *req, int with_sdp)
{
int res;