fix: increment and refactor number of hops for routed messages

chain/network/src/network_protocol/borsh_conv.rs

@@ -171,7 +171,7 @@ impl TryFrom<&net::PeerMessage> for mem::PeerMessage {
             net::PeerMessage::Routed(r) => mem::PeerMessage::Routed(Box::new(RoutedMessageV2 {
                 msg: *r,
                 created_at: None,
-                num_hops: Some(0),
+                num_hops: 0,
             })),
             net::PeerMessage::Disconnect => mem::PeerMessage::Disconnect(mem::Disconnect {
                 // This flag is used by the disconnecting peer to advise the other peer that there

chain/network/src/network_protocol/mod.rs

@@ -686,7 +686,7 @@ pub struct RoutedMessageV2 {
     pub created_at: Option<time::Utc>,
     /// Number of peers this routed message travelled through.
     /// Doesn't include the peers that are the source and the destination of the message.
-    pub num_hops: Option<i32>,
+    pub num_hops: u32,
 }
 
 impl std::ops::Deref for RoutedMessageV2 {
@@ -928,7 +928,7 @@ impl RawRoutedMessage {
                 body: self.body,
             },
             created_at: now,
-            num_hops: Some(0),
+            num_hops: 0,
         }
     }
 }

chain/network/src/network_protocol/network.proto

@@ -11,7 +11,7 @@ import "google/protobuf/timestamp.proto";
 message OwnedAccount {
   PublicKey account_key = 1; // required
   // PeerId of the node owning the account_key.
-  PublicKey peer_id = 2; // required 
+  PublicKey peer_id = 2; // required
   // Timestamp indicates the date of signing - we do not assume the
   // nodes' clocks to be synchronized, but for security if the timestamp
   // deviation is too large, the handshake will be rejected.
@@ -158,7 +158,7 @@ message Handshake {
   uint32 sender_listen_port = 5;
   // Basic info about the NEAR chain that the sender belongs to.
   // Sender expects receiver to belong to the same chain.
-  // In case of mismatch, receiver sends back HandshakeFailure with 
+  // In case of mismatch, receiver sends back HandshakeFailure with
   // reason GenesisMismatch.
   PeerChainInfo sender_chain_info = 6;
   // Edge (sender,receiver) signed by sender, which once signed by
@@ -227,7 +227,7 @@ message AccountData {
   // to a specific peer_id. Then this field won't be necessary.
   // Unless we use it instead of AnnounceAccount.
   PublicKey peer_id = 5; // required.
- 
+
   PublicKey account_key = 6; // required.
 
   // List of nodes which
@@ -244,7 +244,7 @@ message AccountData {
   uint64 version = 7;
   // Time of creation of this AccountData.
   // TODO(gprusak): consider expiring the AccountData based on this field.
-  google.protobuf.Timestamp timestamp = 4; 
+  google.protobuf.Timestamp timestamp = 4;
 }
 
 // Message sent whenever the sender learns about new connections
@@ -261,7 +261,7 @@ message AccountData {
 message RoutingTableUpdate {
   reserved 3,4;
   repeated Edge edges = 1;
-  // list of known NEAR validator accounts 
+  // list of known NEAR validator accounts
   repeated AnnounceAccount accounts = 2;
 }
 
@@ -373,11 +373,14 @@ message SignedTransaction {
 // Wrapper of borsh-encoded RoutedMessage
 // https://github.com/near/nearcore/blob/1a4edefd0116f7d1e222bc96569367a02fe64199/chain/network-primitives/src/network_protocol/mod.rs#L295
 message RoutedMessage {
+  // Deprecated
+  reserved 3;
+
   bytes borsh = 1;
   // Timestamp of creating the Routed message by its original author.
   google.protobuf.Timestamp created_at = 2;
   // Number of peers this routed message travelled through. Doesn't include the peer that created the message.
-  optional int32 num_hops = 3;
+  uint32 num_hops = 4;
 }
 
 // Disconnect is send by a node before closing a TCP connection.
@@ -430,7 +433,7 @@ message StateResponse {
 }
 
 message SnapshotHostInfo {
-  PublicKey peer_id = 1; 
+  PublicKey peer_id = 1;
   CryptoHash sync_hash = 2;
   uint64 epoch_height = 3;
   repeated uint64 shards = 4;
@@ -472,21 +475,21 @@ message PeerMessage {
     LastEdge last_edge = 6;
     RoutingTableUpdate sync_routing_table = 7;
     DistanceVector distance_vector = 28;
-    
+
     UpdateNonceRequest update_nonce_request = 8;
     UpdateNonceResponse update_nonce_response = 9;
 
     SyncAccountsData sync_accounts_data = 25;
 
     PeersRequest peers_request = 10;
     PeersResponse peers_response = 11;
-    
+
     BlockHeadersRequest block_headers_request = 12;
     BlockHeadersResponse block_headers_response = 13;
-    
+
     BlockRequest block_request = 14;
     BlockResponse block_response = 15;
-    
+
     SignedTransaction transaction = 16;
     RoutedMessage routed = 17;
     Disconnect disconnect = 18;

chain/network/src/peer/peer_actor.rs

@@ -1431,6 +1431,7 @@ impl PeerActor {
                     }
                 } else {
                     if msg.decrease_ttl() {
+                        msg.num_hops += 1;
                         self.network_state.send_message_to_peer(&self.clock, conn.tier, msg);
                     } else {
                         #[cfg(test)]

chain/network/src/peer_manager/tests/routing.rs

@@ -879,9 +879,9 @@ async fn max_num_peers_limit() {
     drop(pm3);
 }
 
-/// Test that TTL is handled properly.
+/// Test that TTL and number of hops are handled properly.
 #[tokio::test]
-async fn ttl() {
+async fn ttl_and_num_hops() {
     abort_on_panic();
     let mut rng = make_rng(921853233);
     let rng = &mut rng;
@@ -931,6 +931,7 @@ async fn ttl() {
                 .await;
             assert_eq!(msg.body, got.body);
             assert_eq!(msg.ttl - 1, got.ttl);
+            assert_eq!(msg.num_hops + 1, got.num_hops);
         }
     }
 }

chain/network/src/stats/metrics.rs

@@ -434,17 +434,13 @@ fn record_routed_msg_latency(
 // The routed message reached its destination. If the number of hops is known, then update the
 // corresponding metric.
 fn record_routed_msg_hops(msg: &RoutedMessageV2) {
-    const MAX_NUM_HOPS: i32 = 20;
+    const MAX_NUM_HOPS: u32 = 20;
     // We assume that the number of hops is small.
     // As long as the number of hops is below 10, this metric will not consume too much memory.
-    if let Some(num_hops) = msg.num_hops {
-        if num_hops >= 0 {
-            let num_hops = if num_hops > MAX_NUM_HOPS { MAX_NUM_HOPS } else { num_hops };
-            NETWORK_ROUTED_MSG_NUM_HOPS
-                .with_label_values(&[msg.body_variant(), &num_hops.to_string()])
-                .inc();
-        }
-    }
+    let num_hops = std::cmp::min(MAX_NUM_HOPS, msg.num_hops);
+    NETWORK_ROUTED_MSG_NUM_HOPS
+        .with_label_values(&[msg.body_variant(), &num_hops.to_string()])
+        .inc();
 }
 
 #[derive(Clone, Copy, strum::AsRefStr)]