Enable setting a fixed dandelion peer

config/src/comments.rs

@@ -230,6 +230,10 @@ fn comments() -> HashMap<String, String> {
 
 # 15 = Bit flags for FULL_NODE
 #This structure needs to be changed internally, to make it more configurable
+
+# A prefered dandelion_peer, mainly used for testing dandelion
+# dandelion_peer = \"10.0.0.1:13144\"
+
 "
 		.to_string(),
 	);

p2p/src/peers.rs

@@ -83,24 +83,38 @@ impl Peers {
 	// Update the dandelion relay
 	pub fn update_dandelion_relay(&self) {
 		let peers = self.outgoing_connected_peers();
-
-		match thread_rng().choose(&peers) {
-			Some(peer) => {
-				// Clear the map and add new relay
-				let dandelion_relay = &self.dandelion_relay;
-				dandelion_relay.write().clear();
-				dandelion_relay
-					.write()
-					.insert(Utc::now().timestamp(), peer.clone());
-				debug!(
-					"Successfully updated Dandelion relay to: {}",
-					peer.info.addr
-				);
+		match &self.config.dandelion_peer {
+			Some(ip) => {
+				for peer in &peers {
+					if peer.info.addr == *ip {
+						debug!("Found predefined dandelion peer, setting as relay");
+						self.set_dandelion_relay(peer);
+						return;
+					}
+				}
+				debug!("Could not find predefined dandelion peer among connected peers, choosing random")
 			}
+			None => {}
+		}
+		match thread_rng().choose(&peers) {
+			Some(peer) => self.set_dandelion_relay(peer),
 			None => debug!("Could not update dandelion relay"),
 		};
 	}
 
+	fn set_dandelion_relay(&self, peer: &Arc<Peer>) {
+		// Clear the map and add new relay
+		let dandelion_relay = &self.dandelion_relay;
+		dandelion_relay.write().clear();
+		dandelion_relay
+			.write()
+			.insert(Utc::now().timestamp(), peer.clone());
+		debug!(
+			"Successfully updated Dandelion relay to: {}",
+			peer.info.addr
+		);
+	}
+
 	// Get the dandelion relay
 	pub fn get_dandelion_relay(&self) -> HashMap<i64, Arc<Peer>> {
 		self.dandelion_relay.read().clone()

p2p/src/types.rs

@@ -124,6 +124,8 @@ pub struct P2PConfig {
 	pub peer_max_count: Option<u32>,
 
 	pub peer_min_preferred_count: Option<u32>,
+
+	pub dandelion_peer: Option<SocketAddr>,
 }
 
 /// Default address for peer-to-peer connections.
@@ -142,6 +144,7 @@ impl Default for P2PConfig {
 			ban_window: None,
 			peer_max_count: None,
 			peer_min_preferred_count: None,
+			dandelion_peer: None
 		}
 	}
 }