*: add Copy() to transaction.Transaction and payload.P2PNotaryRequest

Add a method that makes a deep copy of all fields and resets size/hash
caches.

Close #3288

Signed-off-by: Ekaterina Pavlova <ekt@morphbits.io>

pkg/core/transaction/attribute.go

@@ -16,6 +16,8 @@ type AttrValue interface {
 	// json lib and marshaling Value together with type makes code
 	// harder to follow.
 	toJSONMap(map[string]any)
+	// Copy returns a deep copy of the attribute value.
+	Copy() AttrValue
 }
 
 // Attribute represents a Transaction attribute.
@@ -110,3 +112,17 @@ func (attr *Attribute) UnmarshalJSON(data []byte) error {
 	}
 	return json.Unmarshal(data, attr.Value)
 }
+
+// Copy creates a deep copy of the Attribute.
+func (attr *Attribute) Copy() *Attribute {
+	if attr == nil {
+		return nil
+	}
+	cp := &Attribute{
+		Type: attr.Type,
+	}
+	if attr.Value != nil {
+		cp.Value = attr.Value.Copy()
+	}
+	return cp
+}

pkg/core/transaction/attribute_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/nspcc-dev/neo-go/internal/testserdes"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -177,3 +178,39 @@ func TestAttribute_MarshalJSON(t *testing.T) {
 		testserdes.MarshalUnmarshalJSON(t, attr, new(Attribute))
 	})
 }
+
+func TestAttribute_Copy(t *testing.T) {
+	originals := []*Attribute{
+		{Type: HighPriority},
+		{Type: OracleResponseT, Value: &OracleResponse{ID: 123, Code: Success, Result: []byte{1, 2, 3}}},
+		{Type: NotValidBeforeT, Value: &NotValidBefore{Height: 123}},
+		{Type: ConflictsT, Value: &Conflicts{Hash: random.Uint256()}},
+		{Type: NotaryAssistedT, Value: &NotaryAssisted{NKeys: 3}},
+		{Type: ReservedLowerBound, Value: &Reserved{Value: []byte{1, 2, 3, 4, 5}}},
+		{Type: ReservedUpperBound, Value: &Reserved{Value: []byte{1, 2, 3, 4, 5}}},
+		{Type: ReservedLowerBound + 5, Value: &Reserved{Value: []byte{1, 2, 3, 4, 5}}},
+	}
+	require.Nil(t, (*Attribute)(nil).Copy())
+
+	for _, original := range originals {
+		cp := original.Copy()
+		require.NotNil(t, cp)
+		assert.Equal(t, original.Type, cp.Type)
+		assert.Equal(t, original.Value, cp.Value)
+		if original.Value != nil {
+			originalValueCopy := original.Value.Copy()
+			switch originalVal := originalValueCopy.(type) {
+			case *OracleResponse:
+				originalVal.Result = append(originalVal.Result, 0xFF)
+				assert.NotEqual(t, len(original.Value.(*OracleResponse).Result), len(originalVal.Result))
+			case *Conflicts:
+				originalVal.Hash = random.Uint256()
+				assert.NotEqual(t, original.Value.(*Conflicts).Hash, originalVal.Hash)
+			case *NotaryAssisted:
+				originalVal.NKeys++
+				assert.NotEqual(t, original.Value.(*NotaryAssisted).NKeys, originalVal.NKeys)
+			}
+			assert.Equal(t, cp.Value, original.Value)
+		}
+	}
+}

pkg/core/transaction/conflicts.go

@@ -23,3 +23,10 @@ func (c *Conflicts) EncodeBinary(w *io.BinWriter) {
 func (c *Conflicts) toJSONMap(m map[string]any) {
 	m["hash"] = c.Hash
 }
+
+// Copy implements the AttrValue interface.
+func (c *Conflicts) Copy() AttrValue {
+	return &Conflicts{
+		Hash: c.Hash,
+	}
+}

pkg/core/transaction/not_valid_before.go

@@ -22,3 +22,10 @@ func (n *NotValidBefore) EncodeBinary(w *io.BinWriter) {
 func (n *NotValidBefore) toJSONMap(m map[string]any) {
 	m["height"] = n.Height
 }
+
+// Copy implements the AttrValue interface.
+func (n *NotValidBefore) Copy() AttrValue {
+	return &NotValidBefore{
+		Height: n.Height,
+	}
+}

pkg/core/transaction/notary_assisted.go

@@ -22,3 +22,10 @@ func (n *NotaryAssisted) EncodeBinary(w *io.BinWriter) {
 func (n *NotaryAssisted) toJSONMap(m map[string]any) {
 	m["nkeys"] = n.NKeys
 }
+
+// Copy implements the AttrValue interface.
+func (n *NotaryAssisted) Copy() AttrValue {
+	return &NotaryAssisted{
+		NKeys: n.NKeys,
+	}
+}

pkg/core/transaction/oracle.go

@@ -1,6 +1,7 @@
 package transaction
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
 	"math"
@@ -116,3 +117,12 @@ func (r *OracleResponse) toJSONMap(m map[string]any) {
 	m["code"] = r.Code
 	m["result"] = r.Result
 }
+
+// Copy implements the AttrValue interface.
+func (r *OracleResponse) Copy() AttrValue {
+	return &OracleResponse{
+		ID:     r.ID,
+		Code:   r.Code,
+		Result: bytes.Clone(r.Result),
+	}
+}

pkg/core/transaction/reserved.go

@@ -22,3 +22,10 @@ func (e *Reserved) EncodeBinary(w *io.BinWriter) {
 func (e *Reserved) toJSONMap(m map[string]any) {
 	m["value"] = e.Value
 }
+
+// Copy implements the AttrValue interface.
+func (e *Reserved) Copy() AttrValue {
+	return &Reserved{
+		Value: e.Value,
+	}
+}

pkg/core/transaction/signer.go

@@ -86,3 +86,24 @@ func SignersToStackItem(signers []Signer) stackitem.Item {
 	}
 	return stackitem.NewArray(res)
 }
+
+// Copy creates a deep copy of the Signer.
+func (c *Signer) Copy() *Signer {
+	if c == nil {
+		return nil
+	}
+	cp := *c
+	if c.AllowedContracts != nil {
+		cp.AllowedContracts = make([]util.Uint160, len(c.AllowedContracts))
+		copy(cp.AllowedContracts, c.AllowedContracts)
+	}
+	cp.AllowedGroups = keys.PublicKeys(c.AllowedGroups).Copy()
+	if c.Rules != nil {
+		cp.Rules = make([]WitnessRule, len(c.Rules))
+		for i, rule := range c.Rules {
+			cp.Rules[i] = *rule.Copy()
+		}
+	}
+
+	return &cp
+}

pkg/core/transaction/signer_test.go

@@ -32,3 +32,40 @@ func TestCosignerMarshallUnmarshallJSON(t *testing.T) {
 	actual := &Signer{}
 	testserdes.MarshalUnmarshalJSON(t, expected, actual)
 }
+
+func TestSignerCopy(t *testing.T) {
+	pk, err := keys.NewPrivateKey()
+	require.NoError(t, err)
+	require.Nil(t, (*Signer)(nil).Copy())
+
+	original := &Signer{
+		Account:          util.Uint160{1, 2, 3, 4, 5},
+		Scopes:           CustomContracts | CustomGroups | Rules,
+		AllowedContracts: []util.Uint160{{1, 2, 3, 4}, {6, 7, 8, 9}},
+		AllowedGroups:    keys.PublicKeys{pk.PublicKey()},
+		Rules:            []WitnessRule{{Action: WitnessAllow, Condition: ConditionCalledByEntry{}}},
+	}
+
+	cp := original.Copy()
+	require.NotNil(t, cp, "Copied Signer should not be nil")
+
+	require.Equal(t, original.Account, cp.Account)
+	require.Equal(t, original.Scopes, cp.Scopes)
+
+	require.NotSame(t, original.AllowedContracts, cp.AllowedContracts)
+	require.Equal(t, original.AllowedContracts, cp.AllowedContracts)
+
+	require.NotSame(t, original.AllowedGroups, cp.AllowedGroups)
+	require.Equal(t, original.AllowedGroups, cp.AllowedGroups)
+
+	require.NotSame(t, original.Rules, cp.Rules)
+	require.Equal(t, original.Rules, cp.Rules)
+
+	original.AllowedContracts[0][0] = 255
+	original.AllowedGroups[0] = nil
+	original.Rules[0].Action = WitnessDeny
+
+	require.NotEqual(t, original.AllowedContracts[0][0], cp.AllowedContracts[0][0])
+	require.NotEqual(t, original.AllowedGroups[0], cp.AllowedGroups[0])
+	require.NotEqual(t, original.Rules[0].Action, cp.Rules[0].Action)
+}

pkg/core/transaction/transaction.go

@@ -1,6 +1,7 @@
 package transaction
 
 import (
+	"bytes"
 	"crypto/sha256"
 	"encoding/json"
 	"errors"
@@ -468,3 +469,36 @@ func (t *Transaction) ToStackItem() stackitem.Item {
 		stackitem.NewByteArray(t.Script),
 	})
 }
+
+// Copy creates a deep copy of the Transaction, including all slice fields. Cached values like
+// 'hashed' and 'size' are reset to ensure the copy can be modified independently of the original.
+func (t *Transaction) Copy() *Transaction {
+	if t == nil {
+		return nil
+	}
+	cp := *t
+	if t.Attributes != nil {
+		cp.Attributes = make([]Attribute, len(t.Attributes))
+		for i, attr := range t.Attributes {
+			cp.Attributes[i] = *attr.Copy()
+		}
+	}
+	if t.Signers != nil {
+		cp.Signers = make([]Signer, len(t.Signers))
+		for i, signer := range t.Signers {
+			cp.Signers[i] = *signer.Copy()
+		}
+	}
+	if t.Scripts != nil {
+		cp.Scripts = make([]Witness, len(t.Scripts))
+		for i, script := range t.Scripts {
+			cp.Scripts[i] = script.Copy()
+		}
+	}
+	cp.Script = bytes.Clone(t.Script)
+
+	cp.hashed = false
+	cp.size = 0
+	cp.hash = util.Uint256{}
+	return &cp
+}

pkg/core/transaction/transaction_test.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/nspcc-dev/neo-go/internal/random"
 	"github.com/nspcc-dev/neo-go/internal/testserdes"
+	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/encoding/fixedn"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
@@ -321,3 +322,68 @@ func BenchmarkTxHash(b *testing.B) {
 		_ = tx.Hash()
 	}
 }
+
+func TestTransaction_DeepCopy(t *testing.T) {
+	origTx := New([]byte{0x01, 0x02, 0x03}, 1000)
+	origTx.NetworkFee = 2000
+	origTx.SystemFee = 500
+	origTx.Nonce = 12345678
+	origTx.ValidUntilBlock = 100
+	origTx.Version = 1
+	require.Nil(t, (*Transaction)(nil).Copy())
+
+	priv, err := keys.NewPrivateKey()
+	require.NoError(t, err)
+	origTx.Signers = []Signer{
+		{Account: random.Uint160(), Scopes: Global, AllowedContracts: []util.Uint160{random.Uint160()}, AllowedGroups: keys.PublicKeys{priv.PublicKey()}, Rules: []WitnessRule{{Action: 0x01, Condition: ConditionCalledByEntry{}}}},
+		{Account: random.Uint160(), Scopes: CalledByEntry},
+	}
+	origTx.Attributes = []Attribute{
+		{Type: HighPriority, Value: &OracleResponse{
+			ID:     0,
+			Code:   Success,
+			Result: []byte{4, 8, 15, 16, 23, 42},
+		}},
+	}
+	origTx.Scripts = []Witness{
+		{
+			InvocationScript:   []byte{0x04, 0x05},
+			VerificationScript: []byte{0x06, 0x07},
+		},
+	}
+	origTxHash := origTx.Hash()
+
+	copyTx := origTx.Copy()
+
+	require.Equal(t, origTx.Hash(), copyTx.Hash())
+	require.Equal(t, origTx, copyTx)
+	require.Equal(t, origTx.Size(), copyTx.Size())
+
+	copyTx.NetworkFee = 3000
+	copyTx.Signers[0].Scopes = None
+	copyTx.Attributes[0].Type = NotaryAssistedT
+	copyTx.Scripts[0].InvocationScript[0] = 0x08
+	copyTx.hashed = false
+	modifiedCopyTxHash := copyTx.Hash()
+
+	require.NotEqual(t, origTx.NetworkFee, copyTx.NetworkFee)
+	require.NotEqual(t, origTx.Signers[0].Scopes, copyTx.Signers[0].Scopes)
+	require.NotEqual(t, origTx.Attributes, copyTx.Attributes)
+	require.NotEqual(t, origTxHash, modifiedCopyTxHash)
+
+	require.NotEqual(t, &origTx.Scripts[0].InvocationScript[0], &copyTx.Scripts[0].InvocationScript[0])
+	require.NotEqual(t, &origTx.Scripts, &copyTx.Scripts)
+	require.Equal(t, origTx.Scripts[0].VerificationScript, copyTx.Scripts[0].VerificationScript)
+	require.Equal(t, origTx.Signers[0].AllowedContracts, copyTx.Signers[0].AllowedContracts)
+	require.Equal(t, origTx.Signers[0].AllowedGroups, copyTx.Signers[0].AllowedGroups)
+	origGroup := origTx.Signers[0].AllowedGroups[0]
+	copyGroup := copyTx.Signers[0].AllowedGroups[0]
+	require.True(t, origGroup.Equal(copyGroup))
+
+	copyTx.Signers[0].AllowedGroups[0] = nil
+	require.NotEqual(t, origTx.Signers[0].AllowedGroups[0], copyTx.Signers[0].AllowedGroups[0])
+
+	require.Equal(t, origTx.Signers[0].Rules[0], copyTx.Signers[0].Rules[0])
+	copyTx.Signers[0].Rules[0].Action = 0x02
+	require.NotEqual(t, origTx.Signers[0].Rules[0].Action, copyTx.Signers[0].Rules[0].Action)
+}

pkg/core/transaction/witness.go

@@ -1,6 +1,8 @@
 package transaction
 
 import (
+	"bytes"
+
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/util"
@@ -38,3 +40,11 @@ func (w *Witness) EncodeBinary(bw *io.BinWriter) {
 func (w Witness) ScriptHash() util.Uint160 {
 	return hash.Hash160(w.VerificationScript)
 }
+
+// Copy creates a deep copy of the Witness.
+func (w Witness) Copy() Witness {
+	return Witness{
+		InvocationScript:   bytes.Clone(w.InvocationScript),
+		VerificationScript: bytes.Clone(w.VerificationScript),
+	}
+}

pkg/core/transaction/witness_condition.go

@@ -54,6 +54,8 @@ type WitnessCondition interface {
 	DecodeBinarySpecific(*io.BinReader, int)
 	// ToStackItem converts WitnessCondition to stackitem.Item.
 	ToStackItem() stackitem.Item
+	// Copy returns a deep copy of the condition.
+	Copy() WitnessCondition
 
 	json.Marshaler
 }
@@ -139,6 +141,12 @@ func (c *ConditionBoolean) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), bool(*c))
 }
 
+// Copy returns a deep copy of the condition.
+func (c *ConditionBoolean) Copy() WitnessCondition {
+	cc := *c
+	return &cc
+}
+
 // Type implements the WitnessCondition interface and returns condition type.
 func (c *ConditionNot) Type() WitnessConditionType {
 	return WitnessNot
@@ -182,6 +190,12 @@ func (c *ConditionNot) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), c.Condition)
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c *ConditionNot) Copy() WitnessCondition {
+	cp := *c
+	return &cp
+}
+
 // Type implements the WitnessCondition interface and returns condition type.
 func (c *ConditionAnd) Type() WitnessConditionType {
 	return WitnessAnd
@@ -264,6 +278,15 @@ func (c *ConditionAnd) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), []WitnessCondition(*c))
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c *ConditionAnd) Copy() WitnessCondition {
+	cp := make(ConditionAnd, len(*c))
+	for i, cond := range *c {
+		cp[i] = cond.Copy()
+	}
+	return &cp
+}
+
 // Type implements the WitnessCondition interface and returns condition type.
 func (c *ConditionOr) Type() WitnessConditionType {
 	return WitnessOr
@@ -310,6 +333,15 @@ func (c *ConditionOr) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), []WitnessCondition(*c))
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c *ConditionOr) Copy() WitnessCondition {
+	cp := make(ConditionOr, len(*c))
+	for i, cond := range *c {
+		cp[i] = cond.Copy()
+	}
+	return &cp
+}
+
 // Type implements the WitnessCondition interface and returns condition type.
 func (c *ConditionScriptHash) Type() WitnessConditionType {
 	return WitnessScriptHash
@@ -348,6 +380,12 @@ func (c *ConditionScriptHash) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), util.Uint160(*c))
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c *ConditionScriptHash) Copy() WitnessCondition {
+	cc := *c
+	return &cc
+}
+
 // Type implements the WitnessCondition interface and returns condition type.
 func (c *ConditionGroup) Type() WitnessConditionType {
 	return WitnessGroup
@@ -386,6 +424,12 @@ func (c *ConditionGroup) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), keys.PublicKey(*c))
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c *ConditionGroup) Copy() WitnessCondition {
+	cp := *c
+	return &cp
+}
+
 // Type implements the WitnessCondition interface and returns condition type.
 func (c ConditionCalledByEntry) Type() WitnessConditionType {
 	return WitnessCalledByEntry
@@ -421,6 +465,11 @@ func (c ConditionCalledByEntry) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), nil)
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c ConditionCalledByEntry) Copy() WitnessCondition {
+	return ConditionCalledByEntry{}
+}
+
 // Type implements the WitnessCondition interface and returns condition type.
 func (c *ConditionCalledByContract) Type() WitnessConditionType {
 	return WitnessCalledByContract
@@ -459,6 +508,12 @@ func (c *ConditionCalledByContract) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), util.Uint160(*c))
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c *ConditionCalledByContract) Copy() WitnessCondition {
+	cc := *c
+	return &cc
+}
+
 // Type implements the WitnessCondition interface and returns condition type.
 func (c *ConditionCalledByGroup) Type() WitnessConditionType {
 	return WitnessCalledByGroup
@@ -497,6 +552,12 @@ func (c *ConditionCalledByGroup) ToStackItem() stackitem.Item {
 	return condToStackItem(c.Type(), keys.PublicKey(*c))
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c *ConditionCalledByGroup) Copy() WitnessCondition {
+	cp := *c
+	return &cp
+}
+
 // DecodeBinaryCondition decodes and returns condition from the given binary stream.
 func DecodeBinaryCondition(r *io.BinReader) WitnessCondition {
 	return decodeBinaryCondition(r, MaxConditionNesting)

pkg/core/transaction/witness_condition_test.go

@@ -36,6 +36,11 @@ func (c InvalidCondition) ToStackItem() stackitem.Item {
 	panic("invalid")
 }
 
+// Copy implements the WitnessCondition interface and returns a deep copy of the condition.
+func (c InvalidCondition) Copy() WitnessCondition {
+	return c
+}
+
 type condCase struct {
 	condition         WitnessCondition
 	success           bool
@@ -347,3 +352,66 @@ func TestWitnessConditionMatch(t *testing.T) {
 		require.Error(t, err)
 	})
 }
+
+func TestWitnessConditionCopy(t *testing.T) {
+	var someBool = true
+	boolCondition := (*ConditionBoolean)(&someBool)
+	pk, err := keys.NewPrivateKey()
+	require.NoError(t, err)
+
+	conditions := []WitnessCondition{
+		boolCondition,
+		&ConditionNot{Condition: boolCondition},
+		&ConditionAnd{boolCondition, boolCondition},
+		&ConditionOr{boolCondition, boolCondition},
+		&ConditionScriptHash{1, 2, 3},
+		(*ConditionGroup)(pk.PublicKey()),
+		ConditionCalledByEntry{},
+		&ConditionCalledByContract{1, 2, 3},
+		(*ConditionCalledByGroup)(pk.PublicKey()),
+		&ConditionNot{Condition: &ConditionNot{Condition: &ConditionNot{Condition: boolCondition}}},
+	}
+	for _, cond := range conditions {
+		copied := cond.Copy()
+		require.Equal(t, cond, copied)
+
+		switch c := copied.(type) {
+		case *ConditionBoolean:
+			require.NotSame(t, c, cond.(*ConditionBoolean))
+		case *ConditionScriptHash:
+			c[0]++
+			require.NotEqual(t, c, cond.(*ConditionScriptHash))
+		case *ConditionGroup:
+			c = (*ConditionGroup)(pk.PublicKey())
+			require.NotSame(t, c, cond.(*ConditionGroup))
+			newPk, _ := keys.NewPrivateKey()
+			copied = (*ConditionGroup)(newPk.PublicKey())
+			require.NotEqual(t, copied, cond)
+		case *ConditionCalledByContract:
+			c[0]++
+			require.NotEqual(t, c, cond.(*ConditionCalledByContract))
+		case *ConditionCalledByGroup:
+			c = (*ConditionCalledByGroup)(pk.PublicKey())
+			require.NotSame(t, c, cond.(*ConditionCalledByGroup))
+			newPk, _ := keys.NewPrivateKey()
+			copied = (*ConditionCalledByGroup)(newPk.PublicKey())
+			require.NotEqual(t, copied, cond)
+		case *ConditionNot:
+			require.NotSame(t, copied, cond)
+			copied.(*ConditionNot).Condition = ConditionCalledByEntry{}
+			require.NotEqual(t, copied, cond)
+		case *ConditionAnd:
+			require.NotSame(t, copied, cond)
+			(*(copied.(*ConditionAnd)))[0] = ConditionCalledByEntry{}
+			require.NotEqual(t, copied, cond)
+		case *ConditionOr:
+			require.NotSame(t, copied, cond)
+			(*(copied.(*ConditionOr)))[0] = ConditionCalledByEntry{}
+			require.NotEqual(t, copied, cond)
+		case *ConditionCalledByEntry:
+			require.NotSame(t, copied, cond)
+			copied = ConditionCalledByEntry{}
+			require.NotEqual(t, copied, cond)
+		}
+	}
+}

pkg/core/transaction/witness_rule.go

@@ -94,3 +94,11 @@ func (w *WitnessRule) ToStackItem() stackitem.Item {
 		w.Condition.ToStackItem(),
 	})
 }
+
+// Copy creates a deep copy of the WitnessRule.
+func (w *WitnessRule) Copy() *WitnessRule {
+	return &WitnessRule{
+		Action:    w.Action,
+		Condition: w.Condition.Copy(),
+	}
+}

pkg/core/transaction/witness_rule_test.go

@@ -73,3 +73,15 @@ func TestWitnessRule_ToStackItem(t *testing.T) {
 		require.Equal(t, expected, actual, act)
 	}
 }
+
+func TestWitnessRule_Copy(t *testing.T) {
+	b := true
+	wr := &WitnessRule{
+		Action:    WitnessDeny,
+		Condition: (*ConditionBoolean)(&b),
+	}
+	copied := wr.Copy()
+	require.Equal(t, wr.Action, copied.Action)
+	require.Equal(t, wr.Condition, copied.Condition)
+	require.NotSame(t, wr.Condition, copied.Condition)
+}

pkg/core/transaction/witness_test.go

@@ -36,3 +36,16 @@ func TestWitnessSerDes(t *testing.T) {
 	require.Error(t, testserdes.DecodeBinary(bin1, exp))
 	require.Error(t, testserdes.DecodeBinary(bin2, exp))
 }
+
+func TestWitnessCopy(t *testing.T) {
+	original := &Witness{
+		InvocationScript:   []byte{1, 2, 3},
+		VerificationScript: []byte{3, 2, 1},
+	}
+
+	cp := original.Copy()
+	require.Equal(t, *original, cp)
+
+	original.InvocationScript[0] = 0x05
+	require.NotEqual(t, *original, cp)
+}

pkg/network/payload/notary_request.go

@@ -136,3 +136,15 @@ func (r *P2PNotaryRequest) isValid() error {
 	}
 	return nil
 }
+
+// Copy creates a deep copy of P2PNotaryRequest. It creates deep copy of the MainTransaction,
+// FallbackTransaction and Witness, including all slice fields. Cached values like
+// 'hashed' and 'size' of the transactions are reset to ensure the copy can be modified
+// independently of the original.
+func (r *P2PNotaryRequest) Copy() *P2PNotaryRequest {
+	return &P2PNotaryRequest{
+		MainTransaction:     r.MainTransaction.Copy(),
+		FallbackTransaction: r.FallbackTransaction.Copy(),
+		Witness:             r.Witness.Copy(),
+	}
+}

pkg/network/payload/notary_request_test.go

@@ -186,3 +186,69 @@ func TestNotaryRequestBytesFromBytes(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, p, actual)
 }
+
+func TestP2PNotaryRequest_Copy(t *testing.T) {
+	priv, err := keys.NewPrivateKey()
+	require.NoError(t, err)
+	orig := &P2PNotaryRequest{
+		MainTransaction: &transaction.Transaction{
+			NetworkFee:      2000,
+			SystemFee:       500,
+			Nonce:           12345678,
+			ValidUntilBlock: 100,
+			Version:         1,
+			Signers: []transaction.Signer{
+				{Account: random.Uint160(), Scopes: transaction.Global, AllowedContracts: []util.Uint160{random.Uint160()}, AllowedGroups: keys.PublicKeys{priv.PublicKey()}, Rules: []transaction.WitnessRule{{Action: 0x01, Condition: transaction.ConditionCalledByEntry{}}}},
+				{Account: random.Uint160(), Scopes: transaction.CalledByEntry},
+			},
+
+			Attributes: []transaction.Attribute{
+				{Type: transaction.HighPriority, Value: &transaction.OracleResponse{
+					ID:     0,
+					Code:   transaction.Success,
+					Result: []byte{4, 8, 15, 16, 23, 42},
+				}},
+			},
+			Scripts: []transaction.Witness{
+				{
+					InvocationScript:   []byte{0x04, 0x05},
+					VerificationScript: []byte{0x06, 0x07},
+				},
+			}},
+		FallbackTransaction: &transaction.Transaction{
+			Version:    2,
+			SystemFee:  200,
+			NetworkFee: 100,
+			Script:     []byte{3, 2, 1},
+			Signers:    []transaction.Signer{{Account: util.Uint160{4, 5, 6}}},
+			Attributes: []transaction.Attribute{{Type: transaction.NotValidBeforeT}},
+			Scripts: []transaction.Witness{
+				{
+					InvocationScript:   []byte{0x0D, 0x0E},
+					VerificationScript: []byte{0x0F, 0x10},
+				},
+			},
+		},
+		Witness: transaction.Witness{
+			InvocationScript:   []byte{0x11, 0x12},
+			VerificationScript: []byte{0x13, 0x14},
+		},
+	}
+
+	p2pCopy := orig.Copy()
+
+	require.Equal(t, orig, p2pCopy)
+	require.NotSame(t, orig, p2pCopy)
+
+	require.Equal(t, orig.MainTransaction, p2pCopy.MainTransaction)
+	require.Equal(t, orig.FallbackTransaction, p2pCopy.FallbackTransaction)
+	require.Equal(t, orig.Witness, p2pCopy.Witness)
+
+	p2pCopy.MainTransaction.Version = 3
+	p2pCopy.FallbackTransaction.Script[0] = 0x1F
+	p2pCopy.Witness.VerificationScript[1] = 0x22
+
+	require.NotEqual(t, orig.MainTransaction.Version, p2pCopy.MainTransaction.Version)
+	require.NotEqual(t, orig.FallbackTransaction.Script[0], p2pCopy.FallbackTransaction.Script[0])
+	require.NotEqual(t, orig.Witness.VerificationScript[1], p2pCopy.Witness.VerificationScript[1])
+}