[#53] proxy: Allow using proxy by trusted accounts

It was reverted because `Verify` with arguments was not well supported
by the client software. Thanks to recent `System.Runtime.CurrentSigners`
call from neo-go v0.104.0 we can take the best of both worlds.

Verify with argument still looks better (less overhead), but this
implementation should work too. Sadly, `overloads` are not of much use
here because verification routines take the _first_ method from the
manifest, albeit with arbitrary number of arguments.

This reverts commit a0b73150c6 with some
changes on-top.

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

proxy/proxy_contract.go

@@ -5,10 +5,12 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/interop"
 	"github.com/nspcc-dev/neo-go/pkg/interop/native/gas"
 	"github.com/nspcc-dev/neo-go/pkg/interop/native/management"
-	"github.com/nspcc-dev/neo-go/pkg/interop/native/neo"
 	"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
+	"github.com/nspcc-dev/neo-go/pkg/interop/storage"
 )
 
+const accountKeyPrefix = 'a'
+
 // OnNEP17Payment is a callback for NEP-17 compatible native GAS contract.
 func OnNEP17Payment(from interop.Hash160, amount int, data any) {
 	caller := runtime.GetCallingScriptHash()
@@ -39,20 +41,46 @@ func Update(script []byte, manifest []byte, data any) {
 }
 
 // Verify method returns true if transaction contains valid multisignature of
-// Alphabet nodes of the Inner Ring.
+// Alphabet nodes of the Inner Ring or any of the trusted accounts added via AddAccount.
 func Verify() bool {
-	alphabet := neo.GetCommittee()
-	sig := common.Multiaddress(alphabet, false)
-
-	if !runtime.CheckWitness(sig) {
-		sig = common.Multiaddress(alphabet, true)
-		return runtime.CheckWitness(sig)
+	if !runtime.GetScriptContainer().Sender.Equals(runtime.GetExecutingScriptHash()) {
+		return false
 	}
 
+	signers := runtime.CurrentSigners()
+	ctx := storage.GetReadOnlyContext()
+	for i := 1; /* skip sender */ i < len(signers); i++ {
+		if storage.Get(ctx, append([]byte{accountKeyPrefix}, signers[i].Account...)) != nil {
 			return true
 		}
+	}
+
+	if runtime.CheckWitness(common.CommitteeAddress()) {
+		return true
+	}
+
+	if runtime.CheckWitness(common.AlphabetAddress()) {
+		return true
+	}
+
+	return false
+}
 
 // Version returns the version of the contract.
 func Version() int {
 	return common.Version
 }
+
+func AddAccount(addr interop.Hash160) {
+	common.CheckWitness(common.CommitteeAddress())
+
+	ctx := storage.GetContext()
+	storage.Put(ctx, append([]byte{accountKeyPrefix}, addr...), []byte{1})
+}
+
+func RemoveAccount(addr interop.Hash160) {
+	common.CheckWitness(common.CommitteeAddress())
+
+	ctx := storage.GetContext()
+	storage.Delete(ctx, append([]byte{accountKeyPrefix}, addr...))
+}

rpcclient/proxy/client.go

@@ -61,6 +61,50 @@ func (c *ContractReader) Version() (*big.Int, error) {
 	return unwrap.BigInt(c.invoker.Call(c.hash, "version"))
 }
 
+// AddAccount creates a transaction invoking `addAccount` method of the contract.
+// This transaction is signed and immediately sent to the network.
+// The values returned are its hash, ValidUntilBlock value and error if any.
+func (c *Contract) AddAccount(addr util.Uint160) (util.Uint256, uint32, error) {
+	return c.actor.SendCall(c.hash, "addAccount", addr)
+}
+
+// AddAccountTransaction creates a transaction invoking `addAccount` method of the contract.
+// This transaction is signed, but not sent to the network, instead it's
+// returned to the caller.
+func (c *Contract) AddAccountTransaction(addr util.Uint160) (*transaction.Transaction, error) {
+	return c.actor.MakeCall(c.hash, "addAccount", addr)
+}
+
+// AddAccountUnsigned creates a transaction invoking `addAccount` method of the contract.
+// This transaction is not signed, it's simply returned to the caller.
+// Any fields of it that do not affect fees can be changed (ValidUntilBlock,
+// Nonce), fee values (NetworkFee, SystemFee) can be increased as well.
+func (c *Contract) AddAccountUnsigned(addr util.Uint160) (*transaction.Transaction, error) {
+	return c.actor.MakeUnsignedCall(c.hash, "addAccount", nil, addr)
+}
+
+// RemoveAccount creates a transaction invoking `removeAccount` method of the contract.
+// This transaction is signed and immediately sent to the network.
+// The values returned are its hash, ValidUntilBlock value and error if any.
+func (c *Contract) RemoveAccount(addr util.Uint160) (util.Uint256, uint32, error) {
+	return c.actor.SendCall(c.hash, "removeAccount", addr)
+}
+
+// RemoveAccountTransaction creates a transaction invoking `removeAccount` method of the contract.
+// This transaction is signed, but not sent to the network, instead it's
+// returned to the caller.
+func (c *Contract) RemoveAccountTransaction(addr util.Uint160) (*transaction.Transaction, error) {
+	return c.actor.MakeCall(c.hash, "removeAccount", addr)
+}
+
+// RemoveAccountUnsigned creates a transaction invoking `removeAccount` method of the contract.
+// This transaction is not signed, it's simply returned to the caller.
+// Any fields of it that do not affect fees can be changed (ValidUntilBlock,
+// Nonce), fee values (NetworkFee, SystemFee) can be increased as well.
+func (c *Contract) RemoveAccountUnsigned(addr util.Uint160) (*transaction.Transaction, error) {
+	return c.actor.MakeUnsignedCall(c.hash, "removeAccount", nil, addr)
+}
+
 // Update creates a transaction invoking `update` method of the contract.
 // This transaction is signed and immediately sent to the network.
 // The values returned are its hash, ValidUntilBlock value and error if any.

tests/proxy_test.go

@@ -4,9 +4,13 @@ import (
 	"path"
 	"testing"
 
+	"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
+	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/neotest"
 	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+	"github.com/stretchr/testify/require"
 )
 
 const proxyPath = "../proxy"
@@ -36,13 +40,25 @@ func newProxyInvoker(t *testing.T) *neotest.ContractInvoker {
 
 func TestVerify(t *testing.T) {
 	e := newProxyInvoker(t)
+	acc := e.NewAccount(t)
 
-	const method = "verify"
+	gas := e.NewInvoker(e.NativeHash(t, nativenames.Gas), e.Validator)
+	gas.Invoke(t, true, "transfer", e.Validator.ScriptHash(), e.Hash, 100_0000_0000, nil)
 
-	e.Invoke(t, stackitem.NewBool(true), method)
+	s := neotest.NewContractSigner(e.Hash, func(*transaction.Transaction) []any { return nil })
+	t.Run("proxy + committee", func(t *testing.T) {
+		tx := e.PrepareInvocation(t, []byte{byte(opcode.RET)}, []neotest.Signer{s, e.Committee})
+		require.NoError(t, e.Chain.VerifyTx(tx))
+	})
+	t.Run("proxy + custom account", func(t *testing.T) {
+		t.Run("bad, only proxy", func(t *testing.T) {
+			tx := e.PrepareInvocation(t, []byte{byte(opcode.RET)}, []neotest.Signer{s, acc})
+			require.Error(t, e.Chain.VerifyTx(tx))
+		})
 
-	notAlphabet := e.NewAccount(t)
-	cNotAlphabet := e.WithSigners(notAlphabet)
+		e.Invoke(t, stackitem.Null{}, "addAccount", acc.ScriptHash())
 
-	cNotAlphabet.Invoke(t, stackitem.NewBool(false), method)
+		tx := e.PrepareInvocation(t, []byte{byte(opcode.RET)}, []neotest.Signer{s, acc})
+		require.NoError(t, e.Chain.VerifyTx(tx))
+	})
 }