2 files changed, 25 insertions, 8 deletions
diff --git a/p2p/src/routing_table/bucket.rs b/p2p/src/routing_table/bucket.rs
index 13edd24..0f43b13 100644
--- a/p2p/src/routing_table/bucket.rs
+++ b/p2p/src/routing_table/bucket.rs
@@ -6,23 +6,28 @@ use rand::{rngs::OsRng, seq::SliceRandom};
 pub type EntryStatusFlag = u16;
 
 /// The entry is connected.
-pub const CONNECTED_ENTRY: EntryStatusFlag = 0b00001;
+pub const CONNECTED_ENTRY: EntryStatusFlag = 0b000001;
 
 /// The entry is disconnected. This will increase the failure counter.
-pub const DISCONNECTED_ENTRY: EntryStatusFlag = 0b00010;
+pub const DISCONNECTED_ENTRY: EntryStatusFlag = 0b000010;
 
 /// The entry is ready to reconnect, meaning it has either been added and
 /// has no connection attempts, or it has been refreshed.
-pub const PENDING_ENTRY: EntryStatusFlag = 0b00100;
+pub const PENDING_ENTRY: EntryStatusFlag = 0b000100;
 
 /// The entry is unreachable. This will increase the failure counter.
-pub const UNREACHABLE_ENTRY: EntryStatusFlag = 0b01000;
+pub const UNREACHABLE_ENTRY: EntryStatusFlag = 0b001000;
 
 /// The entry is unstable. This will increase the failure counter.
-pub const UNSTABLE_ENTRY: EntryStatusFlag = 0b10000;
+pub const UNSTABLE_ENTRY: EntryStatusFlag = 0b010000;
+
+/// The entry is incompatible. This entry will not contribute to an increase in
+/// failure attempts, instead, it will persist in the routing table for the
+/// lookup process and will only be removed in the presence of a new entry.
+pub const INCOMPATIBLE_ENTRY: EntryStatusFlag = 0b100000;
 
 #[allow(dead_code)]
-pub const ALL_ENTRY: EntryStatusFlag = 0b11111;
+pub const ALL_ENTRY: EntryStatusFlag = 0b111111;
 
 /// A BucketEntry represents a peer in the routing table.
 #[derive(Clone, Debug)]
@@ -38,6 +43,10 @@ impl BucketEntry {
         self.status ^ CONNECTED_ENTRY == 0
     }
 
+    pub fn is_incompatible(&self) -> bool {
+        self.status ^ INCOMPATIBLE_ENTRY == 0
+    }
+
     pub fn is_unreachable(&self) -> bool {
         self.status ^ UNREACHABLE_ENTRY == 0
     }
diff --git a/p2p/src/routing_table/mod.rs b/p2p/src/routing_table/mod.rs
index abf9a08..35729da 100644
--- a/p2p/src/routing_table/mod.rs
+++ b/p2p/src/routing_table/mod.rs
@@ -1,8 +1,8 @@
 mod bucket;
 mod entry;
 pub use bucket::{
-    Bucket, BucketEntry, EntryStatusFlag, CONNECTED_ENTRY, DISCONNECTED_ENTRY, PENDING_ENTRY,
-    UNREACHABLE_ENTRY, UNSTABLE_ENTRY,
+    Bucket, BucketEntry, EntryStatusFlag, CONNECTED_ENTRY, DISCONNECTED_ENTRY, INCOMPATIBLE_ENTRY,
+    PENDING_ENTRY, UNREACHABLE_ENTRY, UNSTABLE_ENTRY,
 };
 pub use entry::{xor_distance, Entry, Key};
 
@@ -82,6 +82,14 @@ impl RoutingTable {
             return AddEntryResult::Added;
         }
 
+        // Replace it with an incompatible entry if one exists.
+        let incompatible_entry = bucket.iter().find(|e| e.is_incompatible()).cloned();
+        if let Some(e) = incompatible_entry {
+            bucket.remove(&e.entry.key);
+            bucket.add(&entry);
+            return AddEntryResult::Added;
+        }
+
         // If the bucket is full, the entry is ignored.
         AddEntryResult::Ignored
     }