Revert: Stop using msg hash as a libp2p msg ID

nomos-libp2p/Cargo.toml

@@ -18,6 +18,7 @@ libp2p = { version = "0.52.4", features = [
   "tokio",
   "secp256k1",
 ] }
+blake2 = { version = "0.10" }
 serde = { version = "1.0.166", features = ["derive"] }
 hex = "0.4.3"
 log = "0.4.19"

nomos-libp2p/src/lib.rs

@@ -9,7 +9,9 @@ use std::time::Duration;
 pub use config::SwarmConfig;
 pub use libp2p;
 
-use libp2p::gossipsub::{MessageId, TopicHash};
+use blake2::digest::{consts::U32, Digest};
+use blake2::Blake2b;
+use libp2p::gossipsub::{Message, MessageId, TopicHash};
 #[allow(deprecated)]
 pub use libp2p::{
     core::upgrade,
@@ -63,14 +65,14 @@ impl Swarm {
         // Wrapping TCP transport into DNS transport to resolve hostnames.
         let tcp_transport = dns::tokio::Transport::system(tcp_transport)?.boxed();
 
+        // TODO: consider using Signed or Anonymous.
+        //       For Anonymous, a custom `message_id` function need to be set
+        //       to prevent all messages from a peer being filtered as duplicates.
         let gossipsub = gossipsub::Behaviour::new(
             gossipsub::MessageAuthenticity::Author(local_peer_id),
             gossipsub::ConfigBuilder::from(config.gossipsub_config.clone())
-                // To use the default `message_id_fn` that uses the message sender info,
-                // we shouldn't use ValidationMode::None that discards sender info
-                // from the received message, which causes the message ID to be created wrongly.
-                // https://github.com/libp2p/rust-libp2p/blob/ec157171a7c1d733dcaff80b00ad9596c15701a1/protocols/gossipsub/src/protocol.rs#L377
-                .validation_mode(gossipsub::ValidationMode::Permissive)
+                .validation_mode(gossipsub::ValidationMode::None)
+                .message_id_fn(compute_message_id)
                 .build()?,
         )?;
 
@@ -156,3 +158,9 @@ impl futures::Stream for Swarm {
         Pin::new(&mut self.swarm).poll_next(cx)
     }
 }
+
+fn compute_message_id(message: &Message) -> MessageId {
+    let mut hasher = Blake2b::<U32>::new();
+    hasher.update(&message.data);
+    MessageId::from(hasher.finalize().to_vec())
+}