MT#55283 allow recording + blackhole

The kernel module must take the recording flag (`do_intercept`) into
account when `blackhole` is set, in order to make sure packets are not
dropped before they're passed to the recorder.

closes #1567

Change-Id: Ie2e0ad3d1941b5224fe823032e8349103c51e919

kernel-module/xt_RTPENGINE.c

@@ -4568,10 +4568,10 @@ not_stun:
 src_check_ok:
 	if (g->target.dtls && is_dtls(skb))
 		goto skip1;
-	if (g->target.non_forwarding) {
+	if (g->target.non_forwarding && !g->target.do_intercept) {
 		if (g->target.blackhole)
-			error_nf_action = NF_DROP;
-		goto skip1;
+			goto do_stats; // and drop
+		goto skip1; // pass to userspace
 	}
 
 	rtp.ok = 0;
@@ -4714,6 +4714,7 @@ no_intercept:
 		}
 	}
 
+do_stats:
 	if (atomic64_read(&g->stats_in.packets)==0)
 		atomic_set(&g->stats_in.tos,in_tos);