Include withdrawals in payload id computation

Author: rubo

src/Nethermind/Nethermind.Consensus/Producers/PayloadAttributes.cs

@@ -1,12 +1,17 @@
 // SPDX-FileCopyrightText: 2022 Demerzel Solutions Limited
 // SPDX-License-Identifier: LGPL-3.0-only
 
+using System.Buffers.Binary;
+using System;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Text;
 using Nethermind.Core;
 using Nethermind.Core.Crypto;
+using Nethermind.Core.Extensions;
 using Nethermind.Core.Specs;
+using Nethermind.State.Proofs;
+using Nethermind.Trie;
 
 namespace Nethermind.Consensus.Producers;
 
@@ -42,6 +47,30 @@ public string ToString(string indentation)
 
         return sb.ToString();
     }
+
+    public string ComputePayloadId(BlockHeader parentHeader)
+    {
+        bool hasWithdrawals = Withdrawals is not null;
+        Span<byte> inputSpan = stackalloc byte[32 + 32 + 32 + 20 + (hasWithdrawals ? 32 : 0)];
+
+        parentHeader.Hash!.Bytes.CopyTo(inputSpan[..32]);
+        BinaryPrimitives.WriteUInt64BigEndian(inputSpan.Slice(56, 8), Timestamp);
+        PrevRandao.Bytes.CopyTo(inputSpan.Slice(64, 32));
+        SuggestedFeeRecipient.Bytes.CopyTo(inputSpan.Slice(96, 20));
+
+        if (hasWithdrawals)
+        {
+            var withdrawalsRootHash = Withdrawals.Count == 0
+                ? PatriciaTree.EmptyTreeHash
+                : new WithdrawalTrie(Withdrawals).RootHash;
+
+            withdrawalsRootHash.Bytes.CopyTo(inputSpan[116..]);
+        }
+
+        ValueKeccak inputHash = ValueKeccak.Compute(inputSpan);
+
+        return inputHash.BytesAsSpan[..8].ToHexString(true);
+    }
 }
 
 public static class PayloadAttributesExtensions

src/Nethermind/Nethermind.Merge.Plugin.Test/EngineModuleTests.V2.cs

@@ -721,6 +721,23 @@ public void Should_print_payload_attributes_as_expected()
             $"PayloadAttributes {{Timestamp: {attrs.Timestamp}, PrevRandao: {attrs.PrevRandao}, SuggestedFeeRecipient: {attrs.SuggestedFeeRecipient}, Withdrawals count: {attrs.Withdrawals.Count}}}");
     }
 
+    [TestCaseSource(nameof(PayloadIdTestCases))]
+    public void Should_compute_payload_id_with_withdrawals((IList<Withdrawal>? Withdrawals, string PayloadId) input)
+    {
+        var blockHeader = Build.A.BlockHeader.TestObject;
+        var payloadAttributes = new PayloadAttributes
+        {
+            PrevRandao = Keccak.Zero,
+            SuggestedFeeRecipient = Address.Zero,
+            Timestamp = 0,
+            Withdrawals = input.Withdrawals
+        };
+
+        var payloadId = payloadAttributes.ComputePayloadId(blockHeader);
+
+        payloadId.Should().Be(input.PayloadId);
+    }
+
     private static async Task<GetPayloadV2Result> BuildAndGetPayloadResultV2(
         IEngineRpcModule rpc, MergeTestBlockchain chain, PayloadAttributes payloadAttributes)
     {
@@ -864,4 +881,14 @@ bool isValid
             Enumerable.Repeat(result, 5)
         );
     }
+
+    protected static IEnumerable<(
+        IList<Withdrawal>? Withdrawals,
+        string payloadId
+        )> PayloadIdTestCases()
+    {
+        yield return (null, "0xd0666188af58eb6f");
+        yield return (Array.Empty<Withdrawal>(), "0xb5f89745e4cfaec0");
+        yield return (new[] { Build.A.Withdrawal.TestObject }, "0x0628b8a79468163e");
+    }
 }