res_pjsip_refer: Fix crash from a REFER and BYE collision.

Analyzing a one-off crash on a busy system showed that processing a REFER
request had a NULL session channel pointer.  The only way I can think of
that could cause this is if an outgoing BYE transaction overlapped the
incoming REFER transaction in a collision.  Asterisk sends a BYE while the
phone sends a REFER to complete an attended transfer.

* Made check the session channel pointer before processing an incoming
REFER request in res_pjsip_refer.

* Fixed similar crash potential for res_pjsip supplement incoming request
processing for res_pjsip_sdp_rtp INFO, res_pjsip_caller_id INVITE/UPDATE,
res_pjsip_messaging MESSAGE, and res_pjsip_send_to_voicemail REFER
messages.

* Made res_pjsip_messaging respond to a message body too large with a 413
instead of ignoring it.

ASTERISK-24700 #close
Reported by: Zane Conkle

Review: https://reviewboard.asterisk.org/r/4417/
........

Merged revisions 431898 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@431899 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 10 insertions, 6 deletions

diff --git a/res/res_pjsip_refer.c b/res/res_pjsip_refer.c
index cc0616e9d..b0755b1ea 100644
--- a/res/res_pjsip_refer.c
+++ b/res/res_pjsip_refer.c
@@ -418,7 +418,7 @@ static void refer_attended_destroy(void *obj)
 	struct refer_attended *attended = obj;
 
 	ao2_cleanup(attended->transferer);
-	ast_channel_unref(attended->transferer_chan);
+	ast_channel_cleanup(attended->transferer_chan);
 	ao2_cleanup(attended->transferer_second);
 	ao2_cleanup(attended->progress);
 }
@@ -674,7 +674,7 @@ static int refer_incoming_attended_request(struct ast_sip_session *session, pjsi
 
 		return 200;
 	} else {
-		const char *context = (session->channel ? pbx_builtin_getvar_helper(session->channel, "TRANSFER_CONTEXT") : "");
+		const char *context = pbx_builtin_getvar_helper(session->channel, "TRANSFER_CONTEXT");
 		struct refer_blind refer = { 0, };
 
 		if (ast_strlen_zero(context)) {
@@ -718,10 +718,6 @@ static int refer_incoming_blind_request(struct ast_sip_session *session, pjsip_r
 	char exten[AST_MAX_EXTENSION];
 	struct refer_blind refer = { 0, };
 
-	if (!session->channel) {
-		return 404;
-	}
-
 	/* If no explicit transfer context has been provided use their configured context */
 	context = pbx_builtin_getvar_helper(session->channel, "TRANSFER_CONTEXT");
 	if (ast_strlen_zero(context)) {
@@ -893,6 +889,14 @@ static int refer_incoming_refer_request(struct ast_sip_session *session, struct
 	static const pj_str_t str_refer_to = { "Refer-To", 8 };
 	static const pj_str_t str_replaces = { "Replaces", 8 };
 
+	if (!session->channel) {
+		/* No channel to refer.  Likely because the call was just hung up. */
+		pjsip_dlg_respond(session->inv_session->dlg, rdata, 404, NULL, NULL, NULL);
+		ast_debug(3, "Received a REFER on a session with no channel from endpoint '%s'.\n",
+			ast_sorcery_object_get_id(session->endpoint));
+		return 0;
+	}
+
 	if (!session->endpoint->allowtransfer) {
 		pjsip_dlg_respond(session->inv_session->dlg, rdata, 603, NULL, NULL, NULL);
 		ast_log(LOG_WARNING, "Endpoint %s transfer attempt blocked due to configuration\n",