core: add System.Runtime.CurrentSigners syscall

Port the https://github.com/neo-project/neo/pull/2827.

Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>

pkg/core/interop/interopnames/names.go

@@ -15,6 +15,7 @@ const (
 	SystemIteratorValue                 = "System.Iterator.Value"
 	SystemRuntimeBurnGas                = "System.Runtime.BurnGas"
 	SystemRuntimeCheckWitness           = "System.Runtime.CheckWitness"
+	SystemRuntimeCurrentSigners         = "System.Runtime.CurrentSigners"
 	SystemRuntimeGasLeft                = "System.Runtime.GasLeft"
 	SystemRuntimeGetAddressVersion      = "System.Runtime.GetAddressVersion"
 	SystemRuntimeGetCallingScriptHash   = "System.Runtime.GetCallingScriptHash"
@@ -52,6 +53,7 @@ var names = []string{
 	SystemIteratorValue,
 	SystemRuntimeBurnGas,
 	SystemRuntimeCheckWitness,
+	SystemRuntimeCurrentSigners,
 	SystemRuntimeGasLeft,
 	SystemRuntimeGetAddressVersion,
 	SystemRuntimeGetCallingScriptHash,

pkg/core/interop/runtime/engine.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/config"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
@@ -179,3 +180,16 @@ func BurnGas(ic *interop.Context) error {
 	}
 	return nil
 }
+
+// CurrentSigners returns signers of the currently loaded transaction or stackitem.Null
+// if script container is not a transaction.
+func CurrentSigners(ic *interop.Context) error {
+	tx, ok := ic.Container.(*transaction.Transaction)
+	if ok {
+		ic.VM.Estack().PushItem(transaction.SignersToStackItem(tx.Signers))
+	} else {
+		ic.VM.Estack().PushItem(stackitem.Null{})
+	}
+
+	return nil
+}

pkg/core/interop/runtime/engine_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/nspcc-dev/neo-go/internal/random"
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"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/smartcontract/callflag"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
@@ -129,3 +130,45 @@ func TestLog(t *testing.T) {
 		require.Equal(t, h.StringLE(), logMsg["script"])
 	})
 }
+
+func TestCurrentSigners(t *testing.T) {
+	t.Run("container is block", func(t *testing.T) {
+		b := block.New(false)
+		ic := &interop.Context{VM: vm.New(), Container: b}
+		require.NoError(t, CurrentSigners(ic))
+		checkStack(t, ic.VM, stackitem.Null{})
+	})
+
+	t.Run("container is transaction", func(t *testing.T) {
+		tx := &transaction.Transaction{
+			Signers: []transaction.Signer{
+				{
+					Account: util.Uint160{1},
+					Scopes:  transaction.None,
+				},
+				{
+					Account: util.Uint160{2},
+					Scopes:  transaction.CalledByEntry,
+				},
+			},
+		}
+		ic := &interop.Context{VM: vm.New(), Container: tx}
+		require.NoError(t, CurrentSigners(ic))
+		checkStack(t, ic.VM, stackitem.NewArray([]stackitem.Item{
+			stackitem.NewArray([]stackitem.Item{
+				stackitem.NewByteArray(util.Uint160{1}.BytesBE()),
+				stackitem.NewBigInteger(big.NewInt(int64(transaction.None))),
+				stackitem.NewArray([]stackitem.Item{}),
+				stackitem.NewArray([]stackitem.Item{}),
+				stackitem.NewArray([]stackitem.Item{}),
+			}),
+			stackitem.NewArray([]stackitem.Item{
+				stackitem.NewByteArray(util.Uint160{2}.BytesBE()),
+				stackitem.NewBigInteger(big.NewInt(int64(transaction.CalledByEntry))),
+				stackitem.NewArray([]stackitem.Item{}),
+				stackitem.NewArray([]stackitem.Item{}),
+				stackitem.NewArray([]stackitem.Item{}),
+			}),
+		}))
+	})
+}

pkg/core/interops.go

@@ -46,6 +46,8 @@ var systemInterops = []interop.Function{
 	{Name: interopnames.SystemRuntimeBurnGas, Func: runtime.BurnGas, Price: 1 << 4, ParamCount: 1},
 	{Name: interopnames.SystemRuntimeCheckWitness, Func: runtime.CheckWitness, Price: 1 << 10,
 		RequiredFlags: callflag.NoneFlag, ParamCount: 1},
+	{Name: interopnames.SystemRuntimeCurrentSigners, Func: runtime.CurrentSigners, Price: 1 << 4,
+		RequiredFlags: callflag.NoneFlag},
 	{Name: interopnames.SystemRuntimeGasLeft, Func: runtime.GasLeft, Price: 1 << 4},
 	{Name: interopnames.SystemRuntimeGetAddressVersion, Func: runtime.GetAddressVersion, Price: 1 << 3},
 	{Name: interopnames.SystemRuntimeGetCallingScriptHash, Func: runtime.GetCallingScriptHash, Price: 1 << 4},

pkg/interop/runtime/runtime.go

@@ -7,6 +7,7 @@ package runtime
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
+	"github.com/nspcc-dev/neo-go/pkg/interop/native/ledger"
 	"github.com/nspcc-dev/neo-go/pkg/interop/neogointernal"
 )
 
@@ -30,6 +31,13 @@ func CheckWitness(hashOrKey []byte) bool {
 	return neogointernal.Syscall1("System.Runtime.CheckWitness", hashOrKey).(bool)
 }
 
+// CurrentSigners returns signers of the currently loaded transaction or nil if
+// executing script container is not a transaction. It uses
+// `System.Runtime.CurrentSigners` syscall.
+func CurrentSigners() []ledger.TransactionSigner {
+	return neogointernal.Syscall0("System.Runtime.CurrentSigners").([]ledger.TransactionSigner)
+}
+
 // LoadScript loads the given bytecode into the VM and executes it with the
 // given call flags and arguments. This bytecode is executed as is from byte 0,
 // it's not a deployed contract that can have methods. The execution context is