From 8dad1fc4aab5d10dd81ac071f99e46bf78b1a4ce Mon Sep 17 00:00:00 2001
From: Adrian Malacoda <adrian.malacoda@monarch-pass.net>
Date: Sat, 25 Feb 2017 21:31:32 -0600
Subject: [PATCH] Do not send events to their originators, or to any event not
 specified in the "to" list.

---
 src/lib.rs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index 9420474..dc2bd6c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -86,8 +86,30 @@ impl Tenquestionmarks {
             loop {
                 match main_receiver.recv() {
                     Ok(envelope) => {
+                        /*
+                         * Check if the target module is a valid destination for the envelope.
+                         * We want to deliver this envelope if all of the following are true:
+                         *    1. The target module is not the originator of the envelope
+                         *    2. The envelope's list of allowed recipients is empty, or specifically
+                         *       names the target module.
+                         */
                         let arc_envelope = Arc::new(envelope);
                         for (key, sender) in &module_senders {
+                            let from_this = String::from(*key);
+                            if Some(from_this.clone()) == arc_envelope.from {
+                                debug!("Refusing to transmit event to its originator ({:?})", from_this);
+                                continue;
+                            }
+                            else if !(arc_envelope.to.is_empty() || !arc_envelope.to.contains(&from_this)) {
+                                debug!(
+                                    "Refusing to transmit envelope from {:?} to {:?} since it is not on the list of allowed recipients ({:?})",
+                                    arc_envelope.from,
+                                    from_this,
+                                    arc_envelope.to
+                                );
+                                continue;
+                            }
+
                             match sender.send(arc_envelope.clone()) {
                                 Err(err) => debug!("Failed to dispatch event to module \"{}\": {:?}", key, err),
                                 Ok(_) => {}