op-service: Define the SuperRoot type (#13670)

* op-service: Define the SuperRoot type

* op-program: Add chain ID to super chain output roots

* Rename

op-service/eth/super_root.go

+package eth
+
+import (
+	"encoding/binary"
+	"errors"
+
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+var (
+	ErrInvalidSuperRoot        = errors.New("invalid super root")
+	ErrInvalidSuperRootVersion = errors.New("invalid super root version")
+	SuperRootVersionV1         = byte(1)
+)
+
+const (
+	// SuperRootVersionV1MinLen is the minimum length of a V1 super root prior to hashing
+	// Must contain a 1 byte version, uint64 timestamp and at least one chain's output root hash
+	SuperRootVersionV1MinLen = 1 + 8 + 32
+)
+
+type Super interface {
+	Version() byte
+	Marshal() []byte
+}
+
+func SuperRoot(super Super) Bytes32 {
+	marshaled := super.Marshal()
+	return Bytes32(crypto.Keccak256Hash(marshaled))
+}
+
+type ChainIDAndOutput struct {
+	ChainID uint64
+	Output  Bytes32
+}
+
+func (c *ChainIDAndOutput) Marshal() []byte {
+	d := make([]byte, 64)
+	binary.BigEndian.PutUint64(d[24:32], c.ChainID)
+	copy(d[32:], c.Output[:])
+	return d
+}
+
+type SuperV1 struct {
+	Timestamp uint64
+	Chains    []ChainIDAndOutput
+}
+
+func (o *SuperV1) Version() byte {
+	return SuperRootVersionV1
+}
+
+func (o *SuperV1) Marshal() []byte {
+	buf := make([]byte, 0, 9+len(o.Chains)*64)
+	version := o.Version()
+	buf = append(buf, version)
+	buf = binary.BigEndian.AppendUint64(buf, o.Timestamp)
+	for _, o := range o.Chains {
+		buf = append(buf, o.Marshal()...)
+	}
+	return buf
+}
+
+func UnmarshalSuperRoot(data []byte) (Super, error) {
+	if len(data) < 1 {
+		return nil, ErrInvalidSuperRoot
+	}
+	ver := data[0]
+	switch ver {
+	case SuperRootVersionV1:
+		return unmarshalSuperRootV1(data)
+	default:
+		return nil, ErrInvalidSuperRootVersion
+	}
+}
+
+func unmarshalSuperRootV1(data []byte) (*SuperV1, error) {
+	// Must contain the version, timestamp and at least one output root.
+	if len(data) < SuperRootVersionV1MinLen {
+		return nil, ErrInvalidSuperRoot
+	}
+	// Must contain complete chain output roots
+	if (len(data)-9)%32 != 0 {
+		return nil, ErrInvalidSuperRoot
+	}
+	var output SuperV1
+	// data[:1] is the version
+	output.Timestamp = binary.BigEndian.Uint64(data[1:9])
+	for i := 9; i < len(data); i += 64 {
+		chainOutput := ChainIDAndOutput{
+			ChainID: binary.BigEndian.Uint64(data[i+24 : i+32]),
+			Output:  Bytes32(data[i+32 : i+64]),
+		}
+		output.Chains = append(output.Chains, chainOutput)
+	}
+	return &output, nil
+}

op-service/eth/super_root_test.go

+package eth
+
+import (
+	"encoding/binary"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestUnmarshalSuperRoot_UnknownVersion(t *testing.T) {
+	_, err := UnmarshalSuperRoot([]byte{0: 0xA, 32: 0xA})
+	require.ErrorIs(t, err, ErrInvalidSuperRootVersion)
+}
+
+func TestUnmarshalSuperRoot_TooShortForVersion(t *testing.T) {
+	_, err := UnmarshalSuperRoot([]byte{})
+	require.ErrorIs(t, err, ErrInvalidSuperRoot)
+}
+
+func TestSuperRootV1Codec(t *testing.T) {
+	t.Run("Valid", func(t *testing.T) {
+		chainA := ChainIDAndOutput{ChainID: 11, Output: Bytes32{0x01}}
+		chainB := ChainIDAndOutput{ChainID: 12, Output: Bytes32{0x02}}
+		chainC := ChainIDAndOutput{ChainID: 13, Output: Bytes32{0x03}}
+		superRoot := SuperV1{
+			Timestamp: 7000,
+			Chains:    []ChainIDAndOutput{chainA, chainB, chainC},
+		}
+		marshaled := superRoot.Marshal()
+		unmarshaled, err := UnmarshalSuperRoot(marshaled)
+		require.NoError(t, err)
+		unmarshaledV1 := unmarshaled.(*SuperV1)
+		require.Equal(t, superRoot, *unmarshaledV1)
+	})
+
+	t.Run("BelowMinLength", func(t *testing.T) {
+		_, err := UnmarshalSuperRoot(append([]byte{SuperRootVersionV1}, 0x01))
+		require.ErrorIs(t, err, ErrInvalidSuperRoot)
+	})
+
+	t.Run("NoChainsIncluded", func(t *testing.T) {
+		_, err := UnmarshalSuperRoot(binary.BigEndian.AppendUint64([]byte{SuperRootVersionV1}, 134058))
+		require.ErrorIs(t, err, ErrInvalidSuperRoot)
+	})
+
+	t.Run("PartialChainSuperRoot", func(t *testing.T) {
+		input := binary.BigEndian.AppendUint64([]byte{SuperRootVersionV1}, 134058)
+		input = append(input, 0x01, 0x02, 0x03)
+		_, err := UnmarshalSuperRoot(input)
+		require.ErrorIs(t, err, ErrInvalidSuperRoot)
+	})
+}