From a3bb5a059612bb0c5885d102831e6e0e2c9bc00b Mon Sep 17 00:00:00 2001
From: stavrosvl7 <stavrosvl7@gmail.com>
Date: Wed, 1 Jul 2026 19:22:16 +0300
Subject: [PATCH] rpc: reject block parameter with neither number nor hash

An EIP-1898 block parameter object specifying neither blockNumber nor
blockHash (e.g. {}) is invalid, but UnmarshalJSON accepted it and it was
only rejected later in the backend with a generic -32000 error. Reject it
during unmarshalling so it surfaces as -32602 (invalid params), mirroring
the existing 'cannot specify both' check.
---
 rpc/types.go      | 3 +++
 rpc/types_test.go | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/rpc/types.go b/rpc/types.go
index 578d3f86dd..7720a8d9c6 100644
--- a/rpc/types.go
+++ b/rpc/types.go
@@ -158,6 +158,9 @@ func (bnh *BlockNumberOrHash) UnmarshalJSON(data []byte) error {
 		if e.BlockNumber != nil && e.BlockHash != nil {
 			return errors.New("cannot specify both BlockHash and BlockNumber, choose one or the other")
 		}
+		if e.BlockNumber == nil && e.BlockHash == nil {
+			return errors.New("must specify either BlockHash or BlockNumber")
+		}
 		bnh.BlockNumber = e.BlockNumber
 		bnh.BlockHash = e.BlockHash
 		bnh.RequireCanonical = e.RequireCanonical
diff --git a/rpc/types_test.go b/rpc/types_test.go
index 9dd6fa6508..35294c3dba 100644
--- a/rpc/types_test.go
+++ b/rpc/types_test.go
@@ -109,6 +109,8 @@ func TestBlockNumberOrHash_UnmarshalJSON(t *testing.T) {
 		27: {`{"blockNumber":"safe"}`, false, BlockNumberOrHashWithNumber(SafeBlockNumber)},
 		28: {`{"blockNumber":"finalized"}`, false, BlockNumberOrHashWithNumber(FinalizedBlockNumber)},
 		29: {`{"blockNumber":"0x1", "blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000"}`, true, BlockNumberOrHash{}},
+		30: {`{}`, true, BlockNumberOrHash{}},
+		31: {`{"requireCanonical":true}`, true, BlockNumberOrHash{}},
 	}
 
 	for i, test := range tests {