A0-1455: Add future protocol and decision process for connection direction (#716)

* Add future protocol and decision process for connection direction

Not used for now, that'll be in the next PR.

* Small review comments

* Massively improve xor computation

* Naming in tests

Author: timorl

finality-aleph/src/validator_network/manager/direction.rs

@@ -0,0 +1,206 @@
+use std::{
+    collections::{HashMap, HashSet},
+    ops::BitXor,
+};
+
+use aleph_primitives::AuthorityId;
+
+use crate::validator_network::Data;
+
+/// Data about peers we know and whether we should connect to them or they to us. For the former
+/// case also keeps the peers' addresses.
+pub struct DirectedPeers<A: Data> {
+    own_id: AuthorityId,
+    outgoing: HashMap<AuthorityId, Vec<A>>,
+    incoming: HashSet<AuthorityId>,
+}
+
+/// Whether we should call the remote or the other way around. We xor the peer ids and based on the
+/// parity of the sum of bits of the result decide whether the caller should be the smaller or
+/// greated lexicographically. They are never equal, because cryptography.
+fn should_we_call(own_id: &[u8], remote_id: &[u8]) -> bool {
+    let xor_sum_parity = (own_id.iter().fold(0u8, BitXor::bitxor)
+        ^ remote_id.iter().fold(0u8, BitXor::bitxor))
+    .count_ones()
+        % 2;
+    match xor_sum_parity == 0 {
+        true => own_id < remote_id,
+        false => own_id > remote_id,
+    }
+}
+
+impl<A: Data> DirectedPeers<A> {
+    /// Create a new set of peers directed using our own peer id.
+    pub fn new(own_id: AuthorityId) -> Self {
+        DirectedPeers {
+            own_id,
+            outgoing: HashMap::new(),
+            incoming: HashSet::new(),
+        }
+    }
+
+    /// Add a peer to the list of peers we want to stay connected to, or
+    /// update the list of addresses if the peer was already added.
+    /// Returns whether we should start attempts at connecting with the peer, which is the case
+    /// exactly when the peer is one with which we should attempt connections AND it was added for
+    /// the first time.
+    pub fn add_peer(&mut self, peer_id: AuthorityId, addresses: Vec<A>) -> bool {
+        match should_we_call(self.own_id.as_ref(), peer_id.as_ref()) {
+            true => self.outgoing.insert(peer_id, addresses).is_none(),
+            false => {
+                // We discard the addresses here, as we will never want to call this peer anyway,
+                // so we don't need them.
+                self.incoming.insert(peer_id);
+                false
+            }
+        }
+    }
+
+    /// Return the addresses of the given peer, or None if we shouldn't attempt connecting with the peer.
+    pub fn peer_addresses(&self, peer_id: &AuthorityId) -> Option<Vec<A>> {
+        self.outgoing.get(peer_id).cloned()
+    }
+
+    /// Whether we should be maintaining a connection with this peer.
+    pub fn interested(&self, peer_id: &AuthorityId) -> bool {
+        self.incoming.contains(peer_id) || self.outgoing.contains_key(peer_id)
+    }
+
+    /// Iterator over the peers we want connections from.
+    pub fn incoming_peers(&self) -> impl Iterator<Item = &AuthorityId> {
+        self.incoming.iter()
+    }
+
+    /// Iterator over the peers we want to connect to.
+    pub fn outgoing_peers(&self) -> impl Iterator<Item = &AuthorityId> {
+        self.outgoing.keys()
+    }
+
+    /// Remove a peer from the list of peers that we want to stay connected with, whether the
+    /// connection was supposed to be incoming or outgoing.
+    pub fn remove_peer(&mut self, peer_id: &AuthorityId) {
+        self.incoming.remove(peer_id);
+        self.outgoing.remove(peer_id);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use aleph_primitives::AuthorityId;
+
+    use super::DirectedPeers;
+    use crate::validator_network::mock::key;
+
+    type Address = String;
+
+    async fn container_with_id() -> (DirectedPeers<Address>, AuthorityId) {
+        let (id, _) = key().await;
+        let container = DirectedPeers::new(id.clone());
+        (container, id)
+    }
+
+    fn some_addresses() -> Vec<Address> {
+        vec![
+            String::from(""),
+            String::from("a/b/c"),
+            String::from("43.43.43.43:43000"),
+        ]
+    }
+
+    #[tokio::test]
+    async fn exactly_one_direction_attempts_connections() {
+        let (mut container0, id0) = container_with_id().await;
+        let (mut container1, id1) = container_with_id().await;
+        let addresses = some_addresses();
+        assert!(
+            container0.add_peer(id1, addresses.clone())
+                != container1.add_peer(id0, addresses.clone())
+        );
+    }
+
+    async fn container_with_added_connecting_peer() -> (DirectedPeers<Address>, AuthorityId) {
+        let (mut container0, id0) = container_with_id().await;
+        let (mut container1, id1) = container_with_id().await;
+        let addresses = some_addresses();
+        match container0.add_peer(id1.clone(), addresses.clone()) {
+            true => (container0, id1),
+            false => {
+                container1.add_peer(id0.clone(), addresses);
+                (container1, id0)
+            }
+        }
+    }
+
+    async fn container_with_added_nonconnecting_peer() -> (DirectedPeers<Address>, AuthorityId) {
+        let (mut container0, id0) = container_with_id().await;
+        let (mut container1, id1) = container_with_id().await;
+        let addresses = some_addresses();
+        match container0.add_peer(id1.clone(), addresses.clone()) {
+            false => (container0, id1),
+            true => {
+                container1.add_peer(id0.clone(), addresses);
+                (container1, id0)
+            }
+        }
+    }
+
+    #[tokio::test]
+    async fn no_connecting_on_subsequent_add() {
+        let (mut container0, id1) = container_with_added_connecting_peer().await;
+        let addresses = some_addresses();
+        assert!(!container0.add_peer(id1, addresses));
+    }
+
+    #[tokio::test]
+    async fn peer_addresses_when_connecting() {
+        let (container0, id1) = container_with_added_connecting_peer().await;
+        assert!(container0.peer_addresses(&id1).is_some());
+    }
+
+    #[tokio::test]
+    async fn no_peer_addresses_when_nonconnecting() {
+        let (container0, id1) = container_with_added_nonconnecting_peer().await;
+        assert!(container0.peer_addresses(&id1).is_none());
+    }
+
+    #[tokio::test]
+    async fn interested_in_connecting() {
+        let (container0, id1) = container_with_added_connecting_peer().await;
+        assert!(container0.interested(&id1));
+    }
+
+    #[tokio::test]
+    async fn interested_in_nonconnecting() {
+        let (container0, id1) = container_with_added_nonconnecting_peer().await;
+        assert!(container0.interested(&id1));
+    }
+
+    #[tokio::test]
+    async fn uninterested_in_unknown() {
+        let (container0, _) = container_with_id().await;
+        let (_, id1) = container_with_id().await;
+        assert!(!container0.interested(&id1));
+    }
+
+    #[tokio::test]
+    async fn connecting_are_outgoing() {
+        let (container0, id1) = container_with_added_connecting_peer().await;
+        assert_eq!(container0.outgoing_peers().collect::<Vec<_>>(), vec![&id1]);
+        assert_eq!(container0.incoming_peers().next(), None);
+    }
+
+    #[tokio::test]
+    async fn nonconnecting_are_incoming() {
+        let (container0, id1) = container_with_added_nonconnecting_peer().await;
+        assert_eq!(container0.incoming_peers().collect::<Vec<_>>(), vec![&id1]);
+        assert_eq!(container0.outgoing_peers().next(), None);
+    }
+
+    #[tokio::test]
+    async fn uninterested_in_removed() {
+        let (mut container0, id1) = container_with_added_connecting_peer().await;
+        assert!(container0.interested(&id1));
+        container0.remove_peer(&id1);
+        assert!(!container0.interested(&id1));
+    }
+}

finality-aleph/src/validator_network/manager/mod.rs

@@ -8,6 +8,9 @@ use futures::channel::mpsc;
 
 use crate::{network::PeerId, validator_network::Data};
 
+#[allow(dead_code)]
+mod direction;
+
 /// Error during sending data through the Manager
 #[derive(Debug, PartialEq, Eq)]
 pub enum SendError {

finality-aleph/src/validator_network/protocols/mod.rs

@@ -14,6 +14,8 @@ use crate::{
 mod handshake;
 mod negotiation;
 mod v0;
+#[allow(dead_code)]
+mod v1;
 
 use handshake::HandshakeError;
 pub use negotiation::{protocol, ProtocolNegotiationError};
@@ -24,6 +26,7 @@ pub type Version = u32;
 /// protocol. Remove after it's no longer needed.
 #[derive(PartialEq, Debug, Eq, Clone, Copy)]
 pub enum ConnectionType {
+    New,
     LegacyIncoming,
     LegacyOutgoing,
 }