res_pjsip_messaging: Check for body in in-dialog message

We now check that a body exists and it has a length > 0 before
attempting to process it.

ASTERISK-28447
Reported-by: Gil Richard

Change-Id: Ic469544b22ab848734636588d4c93426cc6f4b1f

res/res_pjsip_messaging.c

@@ -91,10 +91,13 @@ static enum pjsip_status_code check_content_type_in_dialog(const pjsip_rx_data *
 	static const pj_str_t text = { "text", 4};
 	static const pj_str_t application = { "application", 11};
 
+	if (!(rdata->msg_info.msg->body && rdata->msg_info.msg->body->len > 0)) {
+		return res;
+	}
+
 	/* We'll accept any text/ or application/ content type */
-	if (rdata->msg_info.msg->body && rdata->msg_info.msg->body->len
-		&& (pj_stricmp(&rdata->msg_info.msg->body->content_type.type, &text) == 0
-			|| pj_stricmp(&rdata->msg_info.msg->body->content_type.type, &application) == 0)) {
+	if (pj_stricmp(&rdata->msg_info.msg->body->content_type.type, &text) == 0
+			|| pj_stricmp(&rdata->msg_info.msg->body->content_type.type, &application) == 0) {
 		res = PJSIP_SC_OK;
 	} else if (rdata->msg_info.ctype
 		&& (pj_stricmp(&rdata->msg_info.ctype->media.type, &text) == 0