lambdaclass
diff --git a/‎crates/net/p2p/src/lib.rs‎
Lines changed: 128 additions & 8 deletions b/‎crates/net/p2p/src/lib.rs‎
Lines changed: 128 additions & 8 deletions
@@ -1,6 +1,7 @@
 use std::{
     collections::{HashMap, HashSet},
     net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr},
+    ops::Range,
     time::Duration,
 };
 
@@ -41,7 +42,7 @@ use crate::{
     },
     req_resp::{
         BLOCKS_BY_RANGE_PROTOCOL_V1, BLOCKS_BY_ROOT_PROTOCOL_V1, Codec,
-        MAX_COMPRESSED_PAYLOAD_SIZE, Request, STATUS_PROTOCOL_V1, build_status,
+        MAX_COMPRESSED_PAYLOAD_SIZE, MAX_REQUEST_BLOCKS, Request, STATUS_PROTOCOL_V1, build_status,
         fetch_block_from_peer,
     },
     swarm_adapter::SwarmHandle,
@@ -59,12 +60,81 @@ const MAX_FETCH_RETRIES: u32 = 10;
 const INITIAL_BACKOFF_MS: u64 = 5;
 const BACKOFF_MULTIPLIER: u64 = 2;
 const PEER_REDIAL_INTERVAL_SECS: u64 = 12;
+const MAX_SYNC_RANGE: u64 = MAX_REQUEST_BLOCKS * 64; // 65,536 slots (~3 days)
 
 pub(crate) struct PendingRequest {
     pub(crate) attempts: u32,
     pub(crate) failed_peers: HashSet<PeerId>,
 }
 
+pub(crate) enum PendingRequestKind {
+    Root(H256),
+    Range { start_slot: u64, end_slot: u64 },
+}
+
+pub(crate) struct RangeSyncState {
+    /// Remaining slots to request, with an exclusive end.
+    pub(crate) current_range: Range<u64>,
+    /// Latest advertised head slot for each peer.
+    pub(crate) peer_set: HashMap<PeerId, u64>,
+    pub(crate) in_flight: bool,
+}
+
+impl RangeSyncState {
+    pub(crate) fn new(current_range: Range<u64>, peer: PeerId, peer_head: u64) -> Self {
+        Self {
+            current_range,
+            peer_set: HashMap::from([(peer, peer_head)]),
+            in_flight: false,
+        }
+    }
+
+    pub(crate) fn merge_peer(&mut self, peer: PeerId, peer_head: u64, end_exclusive: u64) {
+        self.peer_set.insert(peer, peer_head);
+        self.current_range.end = self.current_range.end.max(end_exclusive);
+        self.drop_stale_peers();
+    }
+
+    pub(crate) fn next_batch(&self) -> Option<(PeerId, Range<u64>)> {
+        if self.in_flight || self.current_range.is_empty() {
+            return None;
+        }
+
+        let (&peer, &peer_head) = self
+            .peer_set
+            .iter()
+            .filter(|(_, head)| **head >= self.current_range.start)
+            .max_by_key(|(_, head)| **head)?;
+        let peer_end = peer_head.saturating_add(1);
+        let batch_end = self
+            .current_range
+            .start
+            .saturating_add(MAX_REQUEST_BLOCKS)
+            .min(self.current_range.end)
+            .min(peer_end);
+
+        (batch_end > self.current_range.start)
+            .then_some((peer, self.current_range.start..batch_end))
+    }
+
+    pub(crate) fn complete_batch(&mut self, end_slot: u64) {
+        self.in_flight = false;
+        self.current_range.start = self.current_range.start.max(end_slot.saturating_add(1));
+        self.drop_stale_peers();
+    }
+
+    pub(crate) fn fail_peer(&mut self, peer: &PeerId) {
+        self.in_flight = false;
+        self.peer_set.remove(peer);
+        self.drop_stale_peers();
+    }
+
+    fn drop_stale_peers(&mut self) {
+        let start_slot = self.current_range.start;
+        self.peer_set.retain(|_, head| *head >= start_slot);
+    }
+}
+
 // --- Swarm construction ---
 
 /// [libp2p Behaviour](libp2p::swarm::NetworkBehaviour) combining identify, Gossipsub
@@ -300,8 +370,9 @@ impl P2P {
             block_topic: built.block_topic,
             aggregation_topic: built.aggregation_topic,
             connected_peers: HashSet::new(),
-            pending_requests: HashMap::new(),
-            request_id_map: HashMap::new(),
+            pending_root_requests: HashMap::new(),
+            outbound_requests: HashMap::new(),
+            range_sync_state: None,
             bootnode_addrs: built.bootnode_addrs,
             node_names,
         };
@@ -336,8 +407,9 @@ pub struct P2PServer {
     pub(crate) aggregation_topic: libp2p::gossipsub::IdentTopic,
 
     pub(crate) connected_peers: HashSet<PeerId>,
-    pub(crate) pending_requests: HashMap<H256, PendingRequest>,
-    pub(crate) request_id_map: HashMap<OutboundRequestId, H256>,
+    pub(crate) pending_root_requests: HashMap<H256, PendingRequest>,
+    pub(crate) outbound_requests: HashMap<OutboundRequestId, PendingRequestKind>,
+    pub(crate) range_sync_state: Option<RangeSyncState>,
     bootnode_addrs: HashMap<PeerId, Multiaddr>,
     node_names: HashMap<PeerId, String>,
 }
@@ -371,7 +443,7 @@ impl P2PServer {
     ) {
         let root = msg.root;
         // Check if still pending (might have succeeded during backoff)
-        if !self.pending_requests.contains_key(&root) {
+        if !self.pending_root_requests.contains_key(&root) {
             trace!(%root, "Block fetch completed during backoff, skipping retry");
             return;
         }
@@ -380,7 +452,7 @@ impl P2PServer {
 
         if !fetch_block_from_peer(self, root).await {
             tracing::error!(%root, "Failed to retry block fetch, giving up");
-            self.pending_requests.remove(&root);
+            self.pending_root_requests.remove(&root);
         }
     }
 
@@ -436,7 +508,7 @@ impl Handler<FetchBlock> for P2PServer {
     async fn handle(&mut self, msg: FetchBlock, _ctx: &Context<Self>) {
         let root = msg.root;
         // Deduplicate - if already pending, ignore
-        if self.pending_requests.contains_key(&root) {
+        if self.pending_root_requests.contains_key(&root) {
             trace!(%root, "Block fetch already in progress, ignoring duplicate");
             return;
         }
@@ -719,6 +791,54 @@ fn compute_message_id(message: &libp2p::gossipsub::Message) -> libp2p::gossipsub
 mod tests {
     use super::*;
 
+    fn random_peer() -> PeerId {
+        PeerId::from_public_key(&Keypair::generate_ed25519().public())
+    }
+
+    #[test]
+    fn range_sync_state_merges_new_peer_ranges() {
+        let first_peer = random_peer();
+        let second_peer = random_peer();
+        let mut state = RangeSyncState::new(10..101, first_peer, 100);
+
+        state.merge_peer(second_peer, 150, 151);
+
+        assert_eq!(state.current_range, 10..151);
+        assert_eq!(state.peer_set.get(&first_peer), Some(&100));
+        assert_eq!(state.peer_set.get(&second_peer), Some(&150));
+    }
+
+    #[test]
+    fn range_sync_state_allows_only_one_batch_in_flight() {
+        let first_peer = random_peer();
+        let second_peer = random_peer();
+        let mut state = RangeSyncState::new(10..3000, first_peer, 500);
+        state.merge_peer(second_peer, 2000, 3000);
+
+        let (selected_peer, batch) = state.next_batch().expect("batch available");
+        assert_eq!(selected_peer, second_peer);
+        assert_eq!(batch, 10..(10 + MAX_REQUEST_BLOCKS));
+
+        state.in_flight = true;
+        assert!(state.next_batch().is_none());
+    }
+
+    #[test]
+    fn range_sync_state_advances_and_drops_stale_peers() {
+        let stale_peer = random_peer();
+        let current_peer = random_peer();
+        let mut state = RangeSyncState::new(10..3000, stale_peer, 100);
+        state.merge_peer(current_peer, 2999, 3000);
+        state.in_flight = true;
+
+        state.complete_batch(1033);
+
+        assert_eq!(state.current_range, 1034..3000);
+        assert!(!state.in_flight);
+        assert!(!state.peer_set.contains_key(&stale_peer));
+        assert_eq!(state.peer_set.get(&current_peer), Some(&2999));
+    }
+
     #[test]
     fn parse_enrs_extracts_ip_port_and_public_key() {
         // Values taken from a local devnet run with lean-quickstart