Fix sync committee subscription to use subnet indices instead of committee indices (#15885)

Co-authored-by: james-prysm <[email protected]>

Author: terencechain

beacon-chain/rpc/eth/validator/handlers.go

@@ -597,7 +597,18 @@ func (s *Server) SubmitSyncCommitteeSubscription(w http.ResponseWriter, r *http.
 		epochDuration := time.Duration(params.BeaconConfig().SlotsPerEpoch.Mul(params.BeaconConfig().SecondsPerSlot)) * time.Second
 		totalDuration := epochDuration * time.Duration(epochsToWatch)
 
-		cache.SyncSubnetIDs.AddSyncCommitteeSubnets(pubkey48[:], startEpoch, sub.SyncCommitteeIndices, totalDuration)
+		subcommitteeSize := params.BeaconConfig().SyncCommitteeSize / params.BeaconConfig().SyncCommitteeSubnetCount
+		seen := make(map[uint64]bool)
+		var subnetIndices []uint64
+
+		for _, idx := range sub.SyncCommitteeIndices {
+			subnetIdx := idx / subcommitteeSize
+			if !seen[subnetIdx] {
+				seen[subnetIdx] = true
+				subnetIndices = append(subnetIndices, subnetIdx)
+			}
+		}
+		cache.SyncSubnetIDs.AddSyncCommitteeSubnets(pubkey48[:], startEpoch, subnetIndices, totalDuration)
 	}
 }
 

beacon-chain/rpc/eth/validator/handlers_test.go

@@ -1049,9 +1049,8 @@ func TestSubmitSyncCommitteeSubscription(t *testing.T) {
 		s.SubmitSyncCommitteeSubscription(writer, request)
 		assert.Equal(t, http.StatusOK, writer.Code)
 		subnets, _, _, _ := cache.SyncSubnetIDs.GetSyncCommitteeSubnets(pubkeys[1], 0)
-		require.Equal(t, 2, len(subnets))
+		require.Equal(t, 1, len(subnets))
 		assert.Equal(t, uint64(0), subnets[0])
-		assert.Equal(t, uint64(2), subnets[1])
 	})
 	t.Run("multiple", func(t *testing.T) {
 		cache.SyncSubnetIDs.EmptyAllCaches()
@@ -1070,7 +1069,7 @@ func TestSubmitSyncCommitteeSubscription(t *testing.T) {
 		assert.Equal(t, uint64(0), subnets[0])
 		subnets, _, _, _ = cache.SyncSubnetIDs.GetSyncCommitteeSubnets(pubkeys[1], 0)
 		require.Equal(t, 1, len(subnets))
-		assert.Equal(t, uint64(2), subnets[0])
+		assert.Equal(t, uint64(0), subnets[0])
 	})
 	t.Run("no body", func(t *testing.T) {
 		request := httptest.NewRequest(http.MethodPost, "http://example.com", nil)

changelog/ttsao_fix-sync-committee-subnet-indices.md

@@ -0,0 +1,3 @@
+### Fixed
+
+- Fix sync committee subscription to use subnet indices instead of committee indices