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

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

tests/proxy_test.go

@@ -1,12 +1,21 @@
 package tests
 
 import (
+	"errors"
 	"path"
 	"testing"
 
+	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
+	"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/crypto/hash"
+	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/neotest"
 	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
+	"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 +45,76 @@ 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)
+	t.Run("proxy + committee", func(t *testing.T) {
+		s := &proxySigner{contract: e.Hash, account: e.CommitteeHash}
+		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) {
+		s := &proxySigner{contract: e.Hash, account: acc.ScriptHash()}
+		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", s.account)
 
-	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))
+	})
+}
+
+type proxySigner struct {
+	contract util.Uint160
+	account  util.Uint160
+}
+
+var _ neotest.ContractSigner = (*proxySigner)(nil)
+
+func (s *proxySigner) Script() []byte {
+	return nil
+}
+func (s *proxySigner) ScriptHash() util.Uint160 {
+	return s.contract
+}
+func (s *proxySigner) SignHashable(uint32, hash.Hashable) []byte {
+	panic("not implemented")
+}
+func (s *proxySigner) SignTx(_ netmode.Magic, tx *transaction.Transaction) error {
+	pos := -1
+	for i := range tx.Signers {
+		if tx.Signers[i].Account.Equals(s.contract) {
+			pos = i
+			break
+		}
+	}
+	if pos < 0 {
+		return errors.New("transaction is not signed by this account")
+	}
+	if len(tx.Scripts) < pos {
+		return errors.New("transaction is not yet signed by the previous signer")
+	}
+
+	invoc, err := s.InvocationScript(tx)
+	if err != nil {
+		return err
+	}
+
+	w := transaction.Witness{InvocationScript: invoc}
+	if len(tx.Scripts) == pos {
+		tx.Scripts = append(tx.Scripts, w)
+	} else {
+		tx.Scripts[pos].InvocationScript = invoc
+	}
+	return nil
+}
+func (s *proxySigner) InvocationScript(tx *transaction.Transaction) ([]byte, error) {
+	w := io.NewBufBinWriter()
+	emit.Any(w.BinWriter, s.account)
+	return w.Bytes(), nil
 }