process payload (#10054)

beacon-chain/core/blocks/payload.go

@@ -8,6 +8,8 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
 	"github.com/prysmaticlabs/prysm/beacon-chain/state"
 	fieldparams "github.com/prysmaticlabs/prysm/config/fieldparams"
+	"github.com/prysmaticlabs/prysm/encoding/bytesutil"
+	"github.com/prysmaticlabs/prysm/encoding/ssz"
 	ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
 	"github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1/block"
 	"github.com/prysmaticlabs/prysm/time/slots"
@@ -121,6 +123,82 @@ func ValidatePayload(st state.BeaconState, payload *ethpb.ExecutionPayload) erro
 	return nil
 }
 
+// ProcessPayload processes input execution payload using beacon state.
+// ValidatePayloadWhenMergeCompletes validates if payload is valid versus input beacon state.
+// These validation steps ONLY apply to post merge.
+//
+// Spec code:
+// def process_execution_payload(state: BeaconState, payload: ExecutionPayload, execution_engine: ExecutionEngine) -> None:
+//    # Verify consistency of the parent hash with respect to the previous execution payload header
+//    if is_merge_complete(state):
+//        assert payload.parent_hash == state.latest_execution_payload_header.block_hash
+//    # Verify random
+//    assert payload.random == get_randao_mix(state, get_current_epoch(state))
+//    # Verify timestamp
+//    assert payload.timestamp == compute_timestamp_at_slot(state, state.slot)
+//    # Verify the execution payload is valid
+//    assert execution_engine.execute_payload(payload)
+//    # Cache execution payload header
+//    state.latest_execution_payload_header = ExecutionPayloadHeader(
+//        parent_hash=payload.parent_hash,
+//        FeeRecipient=payload.FeeRecipient,
+//        state_root=payload.state_root,
+//        receipt_root=payload.receipt_root,
+//        logs_bloom=payload.logs_bloom,
+//        random=payload.random,
+//        block_number=payload.block_number,
+//        gas_limit=payload.gas_limit,
+//        gas_used=payload.gas_used,
+//        timestamp=payload.timestamp,
+//        extra_data=payload.extra_data,
+//        base_fee_per_gas=payload.base_fee_per_gas,
+//        block_hash=payload.block_hash,
+//        transactions_root=hash_tree_root(payload.transactions),
+//    )
+func ProcessPayload(st state.BeaconState, payload *ethpb.ExecutionPayload) (state.BeaconState, error) {
+	if err := ValidatePayloadWhenMergeCompletes(st, payload); err != nil {
+		return nil, err
+	}
+
+	if err := ValidatePayload(st, payload); err != nil {
+		return nil, err
+	}
+
+	header, err := PayloadToHeader(payload)
+	if err != nil {
+		return nil, err
+	}
+	if err := st.SetLatestExecutionPayloadHeader(header); err != nil {
+		return nil, err
+	}
+	return st, nil
+}
+
+// PayloadToHeader converts `payload` into execution payload header format.
+func PayloadToHeader(payload *ethpb.ExecutionPayload) (*ethpb.ExecutionPayloadHeader, error) {
+	txRoot, err := ssz.TransactionsRoot(payload.Transactions)
+	if err != nil {
+		return nil, err
+	}
+
+	return &ethpb.ExecutionPayloadHeader{
+		ParentHash:       bytesutil.SafeCopyBytes(payload.ParentHash),
+		FeeRecipient:     bytesutil.SafeCopyBytes(payload.FeeRecipient),
+		StateRoot:        bytesutil.SafeCopyBytes(payload.StateRoot),
+		ReceiptRoot:      bytesutil.SafeCopyBytes(payload.ReceiptRoot),
+		LogsBloom:        bytesutil.SafeCopyBytes(payload.LogsBloom),
+		Random:           bytesutil.SafeCopyBytes(payload.Random),
+		BlockNumber:      payload.BlockNumber,
+		GasLimit:         payload.GasLimit,
+		GasUsed:          payload.GasUsed,
+		Timestamp:        payload.Timestamp,
+		ExtraData:        bytesutil.SafeCopyBytes(payload.ExtraData),
+		BaseFeePerGas:    bytesutil.SafeCopyBytes(payload.BaseFeePerGas),
+		BlockHash:        bytesutil.SafeCopyBytes(payload.BlockHash),
+		TransactionsRoot: txRoot[:],
+	}, nil
+}
+
 func isEmptyPayload(p *ethpb.ExecutionPayload) bool {
 	if !bytes.Equal(p.ParentHash, make([]byte, fieldparams.RootLength)) {
 		return false