From 92cef0a740102ca81e646be5db78f4141067d55b Mon Sep 17 00:00:00 2001
From: healthykim <bsbs8645@snu.ac.kr>
Date: Fri, 17 Apr 2026 11:09:50 +0200
Subject: [PATCH] eth/protocols: put empty list as a placeholder for
 unavailable responses

---
 eth/protocols/eth/handler_test.go | 18 +++++++++++-------
 eth/protocols/eth/handlers.go     | 15 +++++++++------
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/eth/protocols/eth/handler_test.go b/eth/protocols/eth/handler_test.go
index e07a591904..52607155ba 100644
--- a/eth/protocols/eth/handler_test.go
+++ b/eth/protocols/eth/handler_test.go
@@ -422,7 +422,7 @@ func testGetBlockBodies(t *testing.T, protocol uint) {
 		{limit + 1, nil, nil, limit}, // No more than the possible block count should be returned
 		{0, []common.Hash{backend.chain.Genesis().Hash()}, []bool{true}, 1},      // The genesis block should be retrievable
 		{0, []common.Hash{backend.chain.CurrentBlock().Hash()}, []bool{true}, 1}, // The chains head block should be retrievable
-		{0, []common.Hash{{}}, []bool{false}, 0},                                 // A non existent block should not be returned
+		{0, []common.Hash{{}}, []bool{false}, 1},                                 // A non existent block should not be returned
 
 		// Existing and non-existing blocks interleaved should not cause problems
 		{0, []common.Hash{
@@ -433,7 +433,7 @@ func testGetBlockBodies(t *testing.T, protocol uint) {
 			{},
 			backend.chain.GetBlockByNumber(100).Hash(),
 			{},
-		}, []bool{false, true, false, true, false, true, false}, 3},
+		}, []bool{false, true, false, true, false, true, false}, 7},
 	}
 	// Run each of the tests and verify the results against the chain
 	for i, tt := range tests {
@@ -460,9 +460,13 @@ func testGetBlockBodies(t *testing.T, protocol uint) {
 		}
 		for j, hash := range tt.explicit {
 			hashes = append(hashes, hash)
-			if tt.available[j] && len(bodies) < tt.expected {
-				block := backend.chain.GetBlockByHash(hash)
-				bodies = append(bodies, encodeBody(block))
+			if len(bodies) < tt.expected {
+				if tt.available[j] {
+					block := backend.chain.GetBlockByHash(hash)
+					bodies = append(bodies, encodeBody(block))
+				} else {
+					bodies = append(bodies, BlockBody{})
+				}
 			}
 		}
 
@@ -590,9 +594,9 @@ func testGetBlockReceipts(t *testing.T, protocol uint) {
 	)
 	for i := uint64(0); i <= backend.chain.CurrentBlock().Number.Uint64(); i++ {
 		if i == 1 {
-			// Insert a missing block hash to verify the server returns a nil placeholder
+			// Insert a missing block hash to verify the server returns an empty placeholder
 			hashes = append(hashes, common.HexToHash("0xdeadbeef"))
-			receipts.Append(nil)
+			receipts.AppendRaw(rlp.EmptyList)
 		}
 		block := backend.chain.GetBlockByNumber(i)
 		hashes = append(hashes, block.Hash())
diff --git a/eth/protocols/eth/handlers.go b/eth/protocols/eth/handlers.go
index bf388a022c..4426a722cf 100644
--- a/eth/protocols/eth/handlers.go
+++ b/eth/protocols/eth/handlers.go
@@ -241,6 +241,9 @@ func ServiceGetBlockBodiesQuery(chain *core.BlockChain, query GetBlockBodiesRequ
 		if data := chain.GetBodyRLP(hash); len(data) != 0 {
 			bodies = append(bodies, data)
 			bytes += len(data)
+		} else {
+			// Append an empty body [[], []] as placeholder for missing block
+			bodies = append(bodies, []byte{0xc2, 0xc0, 0xc0})
 		}
 	}
 	return bodies
@@ -281,18 +284,18 @@ func ServiceGetReceiptsQuery69(chain *core.BlockChain, query GetReceiptsRequest)
 		// Retrieve the requested block's receipts
 		results := chain.GetReceiptsRLP(hash)
 		if results == nil {
-			receipts.Append(nil)
+			receipts.AppendRaw(rlp.EmptyList)
 			continue
 		}
 		body := chain.GetBodyRLP(hash)
 		if body == nil {
-			receipts.Append(nil)
+			receipts.AppendRaw(rlp.EmptyList)
 			continue
 		}
 		results, _, err := blockReceiptsToNetwork(results, body, receiptQueryParams{})
 		if err != nil {
 			log.Error("Error in block receipts conversion", "hash", hash, "err", err)
-			receipts.Append(nil)
+			receipts.AppendRaw(rlp.EmptyList)
 			continue
 		}
 		receipts.AppendRaw(results)
@@ -316,12 +319,12 @@ func serviceGetReceiptsQuery70(chain *core.BlockChain, query GetReceiptsRequest,
 		}
 		results := chain.GetReceiptsRLP(hash)
 		if results == nil {
-			receipts.Append(nil)
+			receipts.AppendRaw(rlp.EmptyList)
 			continue
 		}
 		body := chain.GetBodyRLP(hash)
 		if body == nil {
-			receipts.Append(nil)
+			receipts.AppendRaw(rlp.EmptyList)
 			continue
 		}
 		q := receiptQueryParams{sizeLimit: uint64(maxPacketSize - bytes)}
@@ -331,7 +334,7 @@ func serviceGetReceiptsQuery70(chain *core.BlockChain, query GetReceiptsRequest,
 		results, incomplete, err := blockReceiptsToNetwork(results, body, q)
 		if err != nil {
 			log.Error("Error in block receipts conversion", "hash", hash, "err", err)
-			receipts.Append(nil)
+			receipts.AppendRaw(rlp.EmptyList)
 			continue
 		}
 		if results == nil {