From 3db1655e2cc841ef80a1f3ec4c49875d426e49ee Mon Sep 17 00:00:00 2001
From: Asmaa Magdoub <asmaa@starkware.co>
Date: Thu, 1 Aug 2024 13:36:30 +0300
Subject: [PATCH] fix(consensus): handle nil quorum on different round and
 enable protobuf nil votes

---
 crates/papyrus_protobuf/src/converters/consensus.rs      | 7 ++-----
 crates/sequencing/papyrus_consensus/src/state_machine.rs | 9 +++++++--
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/crates/papyrus_protobuf/src/converters/consensus.rs b/crates/papyrus_protobuf/src/converters/consensus.rs
index 61f8a2c6b7..1e12b3ee77 100644
--- a/crates/papyrus_protobuf/src/converters/consensus.rs
+++ b/crates/papyrus_protobuf/src/converters/consensus.rs
@@ -77,11 +77,8 @@ impl TryFrom<protobuf::Vote> for Vote {
 
         let height = value.height;
         let round = value.round;
-        let block_hash: StarkHash = value
-            .block_hash
-            .ok_or(ProtobufConversionError::MissingField { field_description: "block_hash" })?
-            .try_into()?;
-        let block_hash = Some(BlockHash(block_hash));
+        let block_hash: Option<BlockHash> =
+            value.block_hash.map(|block_hash| block_hash.try_into()).transpose()?.map(BlockHash);
         let voter = value
             .voter
             .ok_or(ProtobufConversionError::MissingField { field_description: "voter" })?
diff --git a/crates/sequencing/papyrus_consensus/src/state_machine.rs b/crates/sequencing/papyrus_consensus/src/state_machine.rs
index 81a2b4bf80..c178754175 100644
--- a/crates/sequencing/papyrus_consensus/src/state_machine.rs
+++ b/crates/sequencing/papyrus_consensus/src/state_machine.rs
@@ -333,8 +333,13 @@ impl StateMachine {
         if *count < self.quorum {
             return VecDeque::new();
         }
-        if block_hash.is_none() && round == self.round {
-            return self.advance_to_round(round + 1, leader_fn);
+        if block_hash.is_none() {
+            if round == self.round {
+                return self.advance_to_round(round + 1, leader_fn);
+            } else {
+                // NIL quorum reached on a different round.
+                return VecDeque::new();
+            }
         }
         let Some(proposed_value) = self.proposals.get(&round) else {
             return VecDeque::new();