neoneo-go/pkg/core/interop/context.go

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package interop
import (
"errors"
"fmt"
"sort"
"github.com/nspcc-dev/neo-go/pkg/core/block"
"github.com/nspcc-dev/neo-go/pkg/core/blockchainer"
"github.com/nspcc-dev/neo-go/pkg/core/dao"
"github.com/nspcc-dev/neo-go/pkg/core/state"
"github.com/nspcc-dev/neo-go/pkg/core/transaction"
"github.com/nspcc-dev/neo-go/pkg/crypto"
"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/smartcontract"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
"go.uber.org/zap"
)
// Context represents context in which interops are executed.
type Context struct {
Chain blockchainer.Blockchainer
Container crypto.Verifiable
Natives []Contract
Trigger trigger.Type
Block *block.Block
Tx *transaction.Transaction
DAO *dao.Cached
Notifications []state.NotificationEvent
Log *zap.Logger
Invocations map[util.Uint160]int
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VM *vm.VM
Functions [][]Function
}
// NewContext returns new interop context.
func NewContext(trigger trigger.Type, bc blockchainer.Blockchainer, d dao.DAO, natives []Contract, block *block.Block, tx *transaction.Transaction, log *zap.Logger) *Context {
dao := dao.NewCached(d)
nes := make([]state.NotificationEvent, 0)
return &Context{
Chain: bc,
Natives: natives,
Trigger: trigger,
Block: block,
Tx: tx,
DAO: dao,
Notifications: nes,
Log: log,
Invocations: make(map[util.Uint160]int),
// Functions is a slice of slices of interops sorted by ID.
Functions: [][]Function{},
}
}
// Function binds function name, id with the function itself and price,
// it's supposed to be inited once for all interopContexts, so it doesn't use
// vm.InteropFuncPrice directly.
type Function struct {
ID uint32
Name string
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Func func(*Context) error
// DisallowCallback is true iff syscall can't be used in a callback.
DisallowCallback bool
// ParamCount is a number of function parameters.
ParamCount int
Price int64
// RequiredFlags is a set of flags which must be set during script invocations.
// Default value is NoneFlag i.e. no flags are required.
RequiredFlags smartcontract.CallFlag
}
// Method is a signature for a native method.
type Method = func(ic *Context, args []stackitem.Item) stackitem.Item
// MethodAndPrice is a native-contract method descriptor.
type MethodAndPrice struct {
Func Method
Price int64
RequiredFlags smartcontract.CallFlag
}
// Contract is an interface for all native contracts.
type Contract interface {
Initialize(*Context) error
Metadata() *ContractMD
}
// ContractMD represents native contract instance.
type ContractMD struct {
Manifest manifest.Manifest
Name string
ContractID int32
Script []byte
Hash util.Uint160
Methods map[string]MethodAndPrice
}
// NewContractMD returns Contract with the specified list of methods.
func NewContractMD(name string) *ContractMD {
c := &ContractMD{
Name: name,
Methods: make(map[string]MethodAndPrice),
}
w := io.NewBufBinWriter()
emit.String(w.BinWriter, c.Name)
emit.Syscall(w.BinWriter, "Neo.Native.Call")
c.Script = w.Bytes()
c.Hash = hash.Hash160(c.Script)
c.Manifest = *manifest.DefaultManifest(c.Hash)
return c
}
// AddMethod adds new method to a native contract.
func (c *ContractMD) AddMethod(md *MethodAndPrice, desc *manifest.Method, safe bool) {
c.Manifest.ABI.Methods = append(c.Manifest.ABI.Methods, *desc)
c.Methods[desc.Name] = *md
if safe {
c.Manifest.SafeMethods.Add(desc.Name)
}
}
// AddEvent adds new event to a native contract.
func (c *ContractMD) AddEvent(name string, ps ...manifest.Parameter) {
c.Manifest.ABI.Events = append(c.Manifest.ABI.Events, manifest.Event{
Name: name,
Parameters: ps,
})
}
// Sort sorts interop functions by id.
func Sort(fs []Function) {
sort.Slice(fs, func(i, j int) bool { return fs[i].ID < fs[j].ID })
}
// GetFunction returns metadata for interop with the specified id.
func (ic *Context) GetFunction(id uint32) *Function {
for _, slice := range ic.Functions {
n := sort.Search(len(slice), func(i int) bool {
return slice[i].ID >= id
})
if n < len(slice) && slice[n].ID == id {
return &slice[n]
}
}
return nil
}
// SyscallHandler handles syscall with id.
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func (ic *Context) SyscallHandler(_ *vm.VM, id uint32) error {
f := ic.GetFunction(id)
if f == nil {
return errors.New("syscall not found")
}
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cf := ic.VM.Context().GetCallFlags()
if !cf.Has(f.RequiredFlags) {
return fmt.Errorf("missing call flags: %05b vs %05b", cf, f.RequiredFlags)
}
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if !ic.VM.AddGas(f.Price) {
return errors.New("insufficient amount of gas")
}
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return f.Func(ic)
}
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// SpawnVM spawns new VM with the specified gas limit and set context.VM field.
func (ic *Context) SpawnVM() *vm.VM {
v := vm.NewWithTrigger(ic.Trigger)
v.GasLimit = -1
v.SyscallHandler = ic.SyscallHandler
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ic.VM = v
return v
}