Prevent exhaustion of system resources through exploitation of event cache

Asterisk maintains an internal cache for devices in the event subsystem. The
device state cache holds the state of each device known to Asterisk, such that
consumers of device state information can query for the last known state for
a particular device, even if it is not part of an active call. The concept of
a device in Asterisk can include entities that do not have a physical
representation. One way that this occurred was when anonymous calls are allowed
in Asterisk. A device was automatically created and stored in the cache for
each anonymous call that occurred; this was possible in the SIP and IAX2
channel drivers and through channel drivers that utilized the
res_jabber/res_xmpp resource modules (Gtalk, Jingle, and Motif). These devices
are never removed from the system, allowing anonymous calls to potentially
exhaust a system's resources.

This patch changes the event cache subsystem and device state management to
no longer cache devices that are not associated with a physical entity.

(issue ASTERISK-20175)
Reported by: Russell Bryant, Leif Madsen, Joshua Colp
Tested by: kmoore
patches:
  event-cachability-3.diff uploaded by jcolp (license 5000)
........

Merged revisions 378303 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 378320 from http://svn.asterisk.org/svn/asterisk/branches/10
........

Merged revisions 378321 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@378322 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 11 insertions, 7 deletions

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index b2b3395c7..18c14eacd 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -6854,7 +6854,7 @@ static int update_call_counter(struct sip_pvt *fup, int event)
 	}
 
 	if (p) {
-		ast_devstate_changed(AST_DEVICE_UNKNOWN, "SIP/%s", p->name);
+		ast_devstate_changed(AST_DEVICE_UNKNOWN, AST_DEVSTATE_CACHABLE, "SIP/%s", p->name);
 		sip_unref_peer(p, "update_call_counter: sip_unref_peer from call counter");
 	}
 	return 0;
@@ -8115,6 +8115,9 @@ static struct ast_channel *sip_new(struct sip_pvt *i, int state, const char *tit
 		ast_jb_configure(tmp, &global_jbconf);
 	}
 
+	if (!i->relatedpeer) {
+		ast_set_flag(ast_channel_flags(tmp), AST_FLAG_DISABLE_DEVSTATE_CACHE);
+	}
 	/* Set channel variables for this call from configuration */
 	for (v = i->chanvars ; v ; v = v->next) {
 		char valuebuf[1024];
@@ -15668,7 +15671,7 @@ static int expire_register(const void *data)
 
 	manager_event(EVENT_FLAG_SYSTEM, "PeerStatus", "ChannelType: SIP\r\nPeer: SIP/%s\r\nPeerStatus: Unregistered\r\nCause: Expired\r\n", peer->name);
 	register_peer_exten(peer, FALSE);	/* Remove regexten */
-	ast_devstate_changed(AST_DEVICE_UNKNOWN, "SIP/%s", peer->name);
+	ast_devstate_changed(AST_DEVICE_UNKNOWN, AST_DEVSTATE_CACHABLE, "SIP/%s", peer->name);
 
 	/* Do we need to release this peer from memory?
 		Only for realtime peers and autocreated peers
@@ -16459,8 +16462,9 @@ static void sip_peer_hold(struct sip_pvt *p, int hold)
 	ast_atomic_fetchadd_int(&p->relatedpeer->onhold, (hold ? +1 : -1));
 
 	/* Request device state update */
-	ast_devstate_changed(AST_DEVICE_UNKNOWN, "SIP/%s", p->relatedpeer->name);
-	
+	ast_devstate_changed(AST_DEVICE_UNKNOWN, (ast_test_flag(ast_channel_flags(p->owner), AST_FLAG_DISABLE_DEVSTATE_CACHE) ? AST_DEVSTATE_NOT_CACHABLE : AST_DEVSTATE_CACHABLE),
+			     "SIP/%s", p->relatedpeer->name);
+
 	return;
 }
 
@@ -16983,7 +16987,7 @@ static enum check_auth_result register_verify(struct sip_pvt *p, struct ast_sock
 		} else {
 			update_peer_lastmsgssent(peer, -1, 0);
 		}
-		ast_devstate_changed(AST_DEVICE_UNKNOWN, "SIP/%s", peer->name);
+		ast_devstate_changed(AST_DEVICE_UNKNOWN, AST_DEVSTATE_CACHABLE, "SIP/%s", peer->name);
 	}
 	if (res < 0) {
 		switch (res) {
@@ -23439,7 +23443,7 @@ static void handle_response_peerpoke(struct sip_pvt *p, int resp, struct sip_req
 
 		ast_log(LOG_NOTICE, "Peer '%s' is now %s. (%dms / %dms)\n",
 			peer->name, s, pingtime, peer->maxms);
-		ast_devstate_changed(AST_DEVICE_UNKNOWN, "SIP/%s", peer->name);
+		ast_devstate_changed(AST_DEVICE_UNKNOWN, AST_DEVSTATE_CACHABLE, "SIP/%s", peer->name);
 		if (sip_cfg.peer_rtupdate) {
 			ast_update_realtime(ast_check_realtime("sipregs") ? "sipregs" : "sippeers", "name", peer->name, "lastms", str_lastms, SENTINEL);
 		}
@@ -29350,7 +29354,7 @@ static int sip_poke_noanswer(const void *data)
 	/* Don't send a devstate change if nothing changed. */
 	if (peer->lastms > -1) {
 		peer->lastms = -1;
-		ast_devstate_changed(AST_DEVICE_UNKNOWN, "SIP/%s", peer->name);
+		ast_devstate_changed(AST_DEVICE_UNKNOWN, AST_DEVSTATE_CACHABLE, "SIP/%s", peer->name);
 	}
 
 	/* Try again quickly */