neoneo-go/pkg/core/interop/contract/call.go

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package contract
import (
"errors"
"fmt"
"math/big"
"strings"
"github.com/nspcc-dev/neo-go/pkg/core/dao"
"github.com/nspcc-dev/neo-go/pkg/core/interop"
"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
"github.com/nspcc-dev/neo-go/pkg/core/state"
"github.com/nspcc-dev/neo-go/pkg/smartcontract"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)
type policyChecker interface {
IsBlocked(*dao.Simple, util.Uint160) bool
}
// LoadToken calls method specified by the token id.
func LoadToken(ic *interop.Context, id int32) error {
ctx := ic.VM.Context()
if !ctx.GetCallFlags().Has(callflag.ReadStates | callflag.AllowCall) {
return errors.New("invalid call flags")
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}
tok := ctx.NEF.Tokens[id]
if int(tok.ParamCount) > ctx.Estack().Len() {
return errors.New("stack is too small")
}
args := make([]stackitem.Item, tok.ParamCount)
for i := range args {
args[i] = ic.VM.Estack().Pop().Item()
}
cs, err := ic.GetContract(tok.Hash)
if err != nil {
return fmt.Errorf("token contract %s not found: %w", tok.Hash.StringLE(), err)
}
return callInternal(ic, cs, tok.Method, tok.CallFlag, tok.HasReturn, args, false)
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}
// Call calls a contract with flags.
func Call(ic *interop.Context) error {
h := ic.VM.Estack().Pop().Bytes()
method := ic.VM.Estack().Pop().String()
fs := callflag.CallFlag(int32(ic.VM.Estack().Pop().BigInt().Int64()))
if fs&^callflag.All != 0 {
return errors.New("call flags out of range")
}
args := ic.VM.Estack().Pop().Array()
u, err := util.Uint160DecodeBytesBE(h)
if err != nil {
return errors.New("invalid contract hash")
}
cs, err := ic.GetContract(u)
if err != nil {
return fmt.Errorf("called contract %s not found: %w", u.StringLE(), err)
}
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if strings.HasPrefix(method, "_") {
return errors.New("invalid method name (starts with '_')")
}
md := cs.Manifest.ABI.GetMethod(method, len(args))
if md == nil {
return fmt.Errorf("method not found: %s/%d", method, len(args))
}
hasReturn := md.ReturnType != smartcontract.VoidType
return callInternal(ic, cs, method, fs, hasReturn, args, !hasReturn)
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}
func callInternal(ic *interop.Context, cs *state.Contract, name string, f callflag.CallFlag,
hasReturn bool, args []stackitem.Item, pushNullOnUnloading bool) error {
md := cs.Manifest.ABI.GetMethod(name, len(args))
if md.Safe {
f &^= (callflag.WriteStates | callflag.AllowNotify)
} else if ctx := ic.VM.Context(); ctx != nil && ctx.IsDeployed() {
curr, err := ic.GetContract(ic.VM.GetCurrentScriptHash())
if err == nil {
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if !curr.Manifest.CanCall(cs.Hash, &cs.Manifest, name) {
return errors.New("disallowed method call")
}
}
}
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return callExFromNative(ic, ic.VM.GetCurrentScriptHash(), cs, name, args, f, hasReturn, pushNullOnUnloading, false)
}
// callExFromNative calls a contract with flags using the provided calling hash.
func callExFromNative(ic *interop.Context, caller util.Uint160, cs *state.Contract,
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name string, args []stackitem.Item, f callflag.CallFlag, hasReturn bool, pushNullOnUnloading bool, callFromNative bool) error {
for _, nc := range ic.Natives {
if nc.Metadata().Name == nativenames.Policy {
var pch = nc.(policyChecker)
if pch.IsBlocked(ic.DAO, cs.Hash) {
return fmt.Errorf("contract %s is blocked", cs.Hash.StringLE())
}
break
}
}
md := cs.Manifest.ABI.GetMethod(name, len(args))
if md == nil {
return fmt.Errorf("method '%s' not found", name)
}
if len(args) != len(md.Parameters) {
return fmt.Errorf("invalid argument count: %d (expected %d)", len(args), len(md.Parameters))
}
methodOff := md.Offset
initOff := -1
md = cs.Manifest.ABI.GetMethod(manifest.MethodInit, 0)
if md != nil {
initOff = md.Offset
}
ic.Invocations[cs.Hash]++
f = ic.VM.Context().GetCallFlags() & f
wrapped := ic.VM.Context().HasTryBlock() && // If the method is not wrapped into try-catch block, then changes should be discarded anyway if exception occurs.
f&(callflag.All^callflag.ReadOnly) != 0 // If the method is safe, then it's read-only and doesn't perform storage changes or emit notifications.
baseNtfCount := len(ic.Notifications)
baseDAO := ic.DAO
if wrapped {
ic.DAO = ic.DAO.GetPrivate()
}
onUnload := func(commit bool) error {
if wrapped {
if commit {
_, err := ic.DAO.Persist()
if err != nil {
return fmt.Errorf("failed to persist changes %w", err)
}
} else {
ic.Notifications = ic.Notifications[:baseNtfCount] // Rollback all notification changes made by current context.
}
ic.DAO = baseDAO
}
if pushNullOnUnloading && commit {
ic.VM.Context().Estack().PushItem(stackitem.Null{}) // Must use current context stack.
}
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if callFromNative && !commit {
return fmt.Errorf("unhandled exception")
}
return nil
}
ic.VM.LoadNEFMethod(&cs.NEF, caller, cs.Hash, f,
hasReturn, methodOff, initOff, onUnload)
for e, i := ic.VM.Estack(), len(args)-1; i >= 0; i-- {
e.PushItem(args[i])
}
return nil
}
// ErrNativeCall is returned for failed calls from native.
var ErrNativeCall = errors.New("failed native call")
// CallFromNative performs synchronous call from native contract.
func CallFromNative(ic *interop.Context, caller util.Uint160, cs *state.Contract, method string, args []stackitem.Item, hasReturn bool) error {
startSize := ic.VM.Istack().Len()
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if err := callExFromNative(ic, caller, cs, method, args, callflag.All, hasReturn, false, true); err != nil {
return err
}
for !ic.VM.HasStopped() && ic.VM.Istack().Len() > startSize {
if err := ic.VM.Step(); err != nil {
return fmt.Errorf("%w: %v", ErrNativeCall, err)
}
}
if ic.VM.HasFailed() {
return ErrNativeCall
}
return nil
}
// GetCallFlags returns current context calling flags.
func GetCallFlags(ic *interop.Context) error {
ic.VM.Estack().PushItem(stackitem.NewBigInteger(big.NewInt(int64(ic.VM.Context().GetCallFlags()))))
return nil
}