neoneo-go/pkg/vm/vm.go

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package vm
import (
"crypto/sha1"
"encoding/binary"
"fmt"
"io/ioutil"
"math/big"
"os"
"reflect"
"text/tabwriter"
"unicode/utf8"
"github.com/CityOfZion/neo-go/pkg/crypto/hash"
"github.com/CityOfZion/neo-go/pkg/crypto/keys"
"github.com/CityOfZion/neo-go/pkg/util"
"github.com/pkg/errors"
)
type errorAtInstruct struct {
ip int
op Instruction
err interface{}
}
func (e *errorAtInstruct) Error() string {
return fmt.Sprintf("error encountered at instruction %d (%s): %s", e.ip, e.op, e.err)
}
func newError(ip int, op Instruction, err interface{}) *errorAtInstruct {
return &errorAtInstruct{ip: ip, op: op, err: err}
}
// StateMessage is a vm state message which could be used as additional info for example by cli.
type StateMessage string
const (
// MaxArraySize is the maximum array size allowed in the VM.
MaxArraySize = 1024
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// MaxItemSize is the maximum item size allowed in the VM.
MaxItemSize = 1024 * 1024
maxSHLArg = 256
minSHLArg = -256
)
// VM represents the virtual machine.
type VM struct {
state State
// registered interop hooks.
interop map[string]InteropFuncPrice
// callback to get scripts.
getScript func(util.Uint160) []byte
istack *Stack // invocation stack.
estack *Stack // execution stack.
astack *Stack // alt stack.
// Hash to verify in CHECKSIG/CHECKMULTISIG.
checkhash []byte
}
// InteropFuncPrice represents an interop function with a price.
type InteropFuncPrice struct {
Func InteropFunc
Price int
}
// New returns a new VM object ready to load .avm bytecode scripts.
func New() *VM {
vm := &VM{
interop: make(map[string]InteropFuncPrice),
getScript: nil,
state: haltState,
istack: NewStack("invocation"),
estack: NewStack("evaluation"),
astack: NewStack("alt"),
}
// Register native interop hooks.
vm.RegisterInteropFunc("Neo.Runtime.Log", runtimeLog, 1)
vm.RegisterInteropFunc("Neo.Runtime.Notify", runtimeNotify, 1)
return vm
}
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// RegisterInteropFunc registers the given InteropFunc to the VM.
func (v *VM) RegisterInteropFunc(name string, f InteropFunc, price int) {
v.interop[name] = InteropFuncPrice{f, price}
}
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// RegisterInteropFuncs registers all interop functions passed in a map in
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// the VM. Effectively it's a batched version of RegisterInteropFunc.
func (v *VM) RegisterInteropFuncs(interops map[string]InteropFuncPrice) {
// We allow reregistration here.
for name, funPrice := range interops {
v.interop[name] = funPrice
}
}
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// Estack returns the evaluation stack so interop hooks can utilize this.
func (v *VM) Estack() *Stack {
return v.estack
}
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// Astack returns the alt stack so interop hooks can utilize this.
func (v *VM) Astack() *Stack {
return v.astack
}
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// Istack returns the invocation stack so interop hooks can utilize this.
func (v *VM) Istack() *Stack {
return v.istack
}
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// LoadArgs loads in the arguments used in the Mian entry point.
func (v *VM) LoadArgs(method []byte, args []StackItem) {
if len(args) > 0 {
v.estack.PushVal(args)
}
if method != nil {
v.estack.PushVal(method)
}
}
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// PrintOps prints the opcodes of the current loaded program to stdout.
func (v *VM) PrintOps() {
w := tabwriter.NewWriter(os.Stdout, 0, 0, 4, ' ', 0)
fmt.Fprintln(w, "INDEX\tOPCODE\tPARAMETER\t")
realctx := v.Context()
ctx := realctx.Copy()
ctx.ip = 0
ctx.nextip = 0
for {
cursor := ""
instr, parameter, err := ctx.Next()
if ctx.ip == realctx.ip {
cursor = "<<"
}
if err != nil {
fmt.Fprintf(w, "%d\t%s\tERROR: %s\t%s\n", ctx.ip, instr, err, cursor)
break
}
var desc = ""
if parameter != nil {
switch instr {
case JMP, JMPIF, JMPIFNOT, CALL:
offset := int16(binary.LittleEndian.Uint16(parameter))
desc = fmt.Sprintf("%d (%d/%x)", ctx.ip+int(offset), offset, parameter)
case SYSCALL:
desc = fmt.Sprintf("%q", parameter)
case APPCALL, TAILCALL:
desc = fmt.Sprintf("%x", parameter)
default:
if utf8.Valid(parameter) {
desc = fmt.Sprintf("%x (%q)", parameter, parameter)
} else {
desc = fmt.Sprintf("%x", parameter)
}
}
}
fmt.Fprintf(w, "%d\t%s\t%s\t%s\n", ctx.ip, instr, desc, cursor)
if ctx.nextip >= len(ctx.prog) {
break
}
}
w.Flush()
}
// AddBreakPoint adds a breakpoint to the current context.
func (v *VM) AddBreakPoint(n int) {
ctx := v.Context()
ctx.breakPoints = append(ctx.breakPoints, n)
}
// AddBreakPointRel adds a breakpoint relative to the current
// instruction pointer.
func (v *VM) AddBreakPointRel(n int) {
ctx := v.Context()
v.AddBreakPoint(ctx.ip + n)
}
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// LoadFile loads a program from the given path, ready to execute it.
func (v *VM) LoadFile(path string) error {
b, err := ioutil.ReadFile(path)
if err != nil {
return err
}
v.Load(b)
return nil
}
// Load initializes the VM with the program given.
func (v *VM) Load(prog []byte) {
// Clear all stacks and state, it could be a reload.
v.istack.Clear()
v.estack.Clear()
v.astack.Clear()
v.state = noneState
v.LoadScript(prog)
}
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// LoadScript loads a script from the internal script table. It
// will immediately push a new context created from this script to
// the invocation stack and starts executing it.
func (v *VM) LoadScript(b []byte) {
ctx := NewContext(b)
ctx.estack = v.estack
ctx.astack = v.astack
v.istack.PushVal(ctx)
}
// Context returns the current executed context. Nil if there is no context,
// which implies no program is loaded.
func (v *VM) Context() *Context {
if v.istack.Len() == 0 {
return nil
}
return v.istack.Peek(0).Value().(*Context)
}
// PopResult is used to pop the first item of the evaluation stack. This allows
// us to test compiler and vm in a bi-directional way.
func (v *VM) PopResult() interface{} {
e := v.estack.Pop()
if e != nil {
return e.Value()
}
return nil
}
// Stack returns json formatted representation of the given stack.
func (v *VM) Stack(n string) string {
var s *Stack
if n == "astack" {
s = v.astack
}
if n == "istack" {
s = v.istack
}
if n == "estack" {
s = v.estack
}
return buildStackOutput(s)
}
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// Ready returns true if the VM ready to execute the loaded program.
// Will return false if no program is loaded.
func (v *VM) Ready() bool {
return v.istack.Len() > 0
}
// Run starts the execution of the loaded program.
func (v *VM) Run() error {
if !v.Ready() {
v.state = faultState
return errors.New("no program loaded")
}
if v.state.HasFlag(faultState) {
// VM already ran something and failed, in general its state is
// undefined in this case so we can't run anything.
return errors.New("VM has failed")
}
// haltState (the default) or breakState are safe to continue.
v.state = noneState
for {
// check for breakpoint before executing the next instruction
ctx := v.Context()
if ctx != nil && ctx.atBreakPoint() {
v.state |= breakState
}
switch {
case v.state.HasFlag(faultState):
// Should be caught and reported already by the v.Step(),
// but we're checking here anyway just in case.
return errors.New("VM has failed")
case v.state.HasFlag(haltState), v.state.HasFlag(breakState):
// Normal exit from this loop.
return nil
case v.state == noneState:
if err := v.Step(); err != nil {
return err
}
default:
v.state = faultState
return errors.New("unknown state")
}
}
}
// Step 1 instruction in the program.
func (v *VM) Step() error {
ctx := v.Context()
op, param, err := ctx.Next()
if err != nil {
v.state = faultState
return newError(ctx.ip, op, err)
}
return v.execute(ctx, op, param)
}
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// StepInto behaves the same as “step over” in case if the line does not contain a function. Otherwise
// the debugger will enter the called function and continue line-by-line debugging there.
func (v *VM) StepInto() error {
ctx := v.Context()
if ctx == nil {
v.state |= haltState
}
if v.HasStopped() {
return nil
}
if ctx != nil && ctx.prog != nil {
op, param, err := ctx.Next()
if err != nil {
v.state = faultState
return newError(ctx.ip, op, err)
}
vErr := v.execute(ctx, op, param)
if vErr != nil {
return vErr
}
}
cctx := v.Context()
if cctx != nil && cctx.atBreakPoint() {
v.state = breakState
}
return nil
}
// StepOut takes the debugger to the line where the current function was called.
func (v *VM) StepOut() error {
var err error
if v.state == breakState {
v.state = noneState
} else {
v.state = breakState
}
expSize := v.istack.len
for v.state.HasFlag(noneState) && v.istack.len >= expSize {
err = v.StepInto()
}
return err
}
// StepOver takes the debugger to the line that will step over a given line.
// If the line contains a function the function will be executed and the result returned without debugging each line.
func (v *VM) StepOver() error {
var err error
if v.HasStopped() {
return err
}
if v.state == breakState {
v.state = noneState
} else {
v.state = breakState
}
expSize := v.istack.len
for {
err = v.StepInto()
if !(v.state.HasFlag(noneState) && v.istack.len > expSize) {
break
}
}
return err
}
// HasFailed returns whether VM is in the failed state now. Usually used to
// check status after Run.
func (v *VM) HasFailed() bool {
return v.state.HasFlag(faultState)
}
// HasStopped returns whether VM is in Halt or Failed state.
func (v *VM) HasStopped() bool {
return v.state.HasFlag(haltState) || v.state.HasFlag(faultState)
}
// HasHalted returns whether VM is in Halt state.
func (v *VM) HasHalted() bool {
return v.state.HasFlag(haltState)
}
// AtBreakpoint returns whether VM is at breakpoint.
func (v *VM) AtBreakpoint() bool {
return v.state.HasFlag(breakState)
}
// SetCheckedHash sets checked hash for CHECKSIG and CHECKMULTISIG instructions.
func (v *VM) SetCheckedHash(h []byte) {
v.checkhash = make([]byte, len(h))
copy(v.checkhash, h)
}
// SetScriptGetter sets the script getter for CALL instructions.
func (v *VM) SetScriptGetter(gs func(util.Uint160) []byte) {
v.getScript = gs
}
// execute performs an instruction cycle in the VM. Acting on the instruction (opcode).
func (v *VM) execute(ctx *Context, op Instruction, parameter []byte) (err error) {
// Instead of polluting the whole VM logic with error handling, we will recover
// each panic at a central point, putting the VM in a fault state and setting error.
defer func() {
if errRecover := recover(); errRecover != nil {
v.state = faultState
err = newError(ctx.ip, op, errRecover)
}
}()
if op >= PUSHBYTES1 && op <= PUSHBYTES75 {
v.estack.PushVal(parameter)
return
}
switch op {
case PUSHM1, PUSH1, PUSH2, PUSH3, PUSH4, PUSH5,
PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11,
PUSH12, PUSH13, PUSH14, PUSH15, PUSH16:
val := int(op) - int(PUSH1) + 1
v.estack.PushVal(val)
case PUSH0:
v.estack.PushVal([]byte{})
case PUSHDATA1, PUSHDATA2, PUSHDATA4:
v.estack.PushVal(parameter)
// Stack operations.
case TOALTSTACK:
v.astack.Push(v.estack.Pop())
case FROMALTSTACK:
v.estack.Push(v.astack.Pop())
case DUPFROMALTSTACK:
v.estack.Push(v.astack.Dup(0))
case DUP:
v.estack.Push(v.estack.Dup(0))
case SWAP:
a := v.estack.Pop()
b := v.estack.Pop()
v.estack.Push(a)
v.estack.Push(b)
case TUCK:
a := v.estack.Dup(0)
if a == nil {
panic("no top-level element found")
}
if v.estack.Len() < 2 {
panic("can't TUCK with a one-element stack")
}
v.estack.InsertAt(a, 2)
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case CAT:
b := v.estack.Pop().Bytes()
a := v.estack.Pop().Bytes()
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if l := len(a) + len(b); l > MaxItemSize {
panic(fmt.Sprintf("too big item: %d", l))
}
ab := append(a, b...)
v.estack.PushVal(ab)
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case SUBSTR:
l := int(v.estack.Pop().BigInt().Int64())
if l < 0 {
panic("negative length")
}
o := int(v.estack.Pop().BigInt().Int64())
if o < 0 {
panic("negative index")
}
s := v.estack.Pop().Bytes()
if o > len(s) {
panic("invalid offset")
}
last := l + o
if last > len(s) {
last = len(s)
}
v.estack.PushVal(s[o:last])
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case LEFT:
l := int(v.estack.Pop().BigInt().Int64())
if l < 0 {
panic("negative length")
}
s := v.estack.Pop().Bytes()
if t := len(s); l > t {
l = t
}
v.estack.PushVal(s[:l])
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case RIGHT:
l := int(v.estack.Pop().BigInt().Int64())
if l < 0 {
panic("negative length")
}
s := v.estack.Pop().Bytes()
v.estack.PushVal(s[len(s)-l:])
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case XDROP:
n := int(v.estack.Pop().BigInt().Int64())
if n < 0 {
panic("invalid length")
}
e := v.estack.RemoveAt(n)
if e == nil {
panic("bad index")
}
case XSWAP:
n := int(v.estack.Pop().BigInt().Int64())
if n < 0 {
panic("XSWAP: invalid length")
}
// Swap values of elements instead of reordering stack elements.
if n > 0 {
a := v.estack.Peek(n)
b := v.estack.Peek(0)
aval := a.value
bval := b.value
a.value = bval
b.value = aval
}
case XTUCK:
n := int(v.estack.Pop().BigInt().Int64())
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if n <= 0 {
panic("XTUCK: invalid length")
}
a := v.estack.Dup(0)
if a == nil {
panic("no top-level element found")
}
if n > v.estack.Len() {
panic("can't push to the position specified")
}
v.estack.InsertAt(a, n)
case ROT:
e := v.estack.RemoveAt(2)
if e == nil {
panic("no top-level element found")
}
v.estack.Push(e)
case DEPTH:
v.estack.PushVal(v.estack.Len())
case NIP:
elem := v.estack.RemoveAt(1)
if elem == nil {
panic("no second element found")
}
case OVER:
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a := v.estack.Peek(1)
if a == nil {
panic("no second element found")
}
v.estack.Push(a)
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case PICK:
n := int(v.estack.Pop().BigInt().Int64())
if n < 0 {
panic("negative stack item returned")
}
a := v.estack.Peek(n)
if a == nil {
panic("no nth element found")
}
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v.estack.Push(a)
case ROLL:
n := int(v.estack.Pop().BigInt().Int64())
if n < 0 {
panic("negative stack item returned")
}
if n > 0 {
e := v.estack.RemoveAt(n)
if e == nil {
panic("bad index")
}
v.estack.Push(e)
}
case DROP:
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if v.estack.Len() < 1 {
panic("stack is too small")
}
v.estack.Pop()
case EQUAL:
b := v.estack.Pop()
if b == nil {
panic("no top-level element found")
}
a := v.estack.Pop()
if a == nil {
panic("no second-to-the-top element found")
}
if ta, ok := a.value.(*ArrayItem); ok {
if tb, ok := b.value.(*ArrayItem); ok {
v.estack.PushVal(ta == tb)
break
}
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} else if ma, ok := a.value.(*MapItem); ok {
if mb, ok := b.value.(*MapItem); ok {
v.estack.PushVal(ma == mb)
break
}
}
v.estack.PushVal(reflect.DeepEqual(a, b))
// Bit operations.
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case INVERT:
// inplace
a := v.estack.Peek(0).BigInt()
a.Not(a)
case AND:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).And(b, a))
case OR:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Or(b, a))
case XOR:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Xor(b, a))
// Numeric operations.
case ADD:
a := v.estack.Pop().BigInt()
b := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Add(a, b))
case SUB:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Sub(a, b))
case DIV:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Div(a, b))
case MUL:
a := v.estack.Pop().BigInt()
b := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Mul(a, b))
case MOD:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Mod(a, b))
case SHL, SHR:
b := v.estack.Pop().BigInt().Int64()
if b == 0 {
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return
} else if b < minSHLArg || b > maxSHLArg {
panic(fmt.Sprintf("operand must be between %d and %d", minSHLArg, maxSHLArg))
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}
a := v.estack.Pop().BigInt()
if op == SHL {
v.estack.PushVal(new(big.Int).Lsh(a, uint(b)))
} else {
v.estack.PushVal(new(big.Int).Rsh(a, uint(b)))
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}
case BOOLAND:
b := v.estack.Pop().Bool()
a := v.estack.Pop().Bool()
v.estack.PushVal(a && b)
case BOOLOR:
b := v.estack.Pop().Bool()
a := v.estack.Pop().Bool()
v.estack.PushVal(a || b)
case NUMEQUAL:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(a.Cmp(b) == 0)
case NUMNOTEQUAL:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(a.Cmp(b) != 0)
case LT:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(a.Cmp(b) == -1)
case GT:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(a.Cmp(b) == 1)
case LTE:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(a.Cmp(b) <= 0)
case GTE:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
v.estack.PushVal(a.Cmp(b) >= 0)
case MIN:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
val := a
if a.Cmp(b) == 1 {
val = b
}
v.estack.PushVal(val)
case MAX:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
val := a
if a.Cmp(b) == -1 {
val = b
}
v.estack.PushVal(val)
case WITHIN:
b := v.estack.Pop().BigInt()
a := v.estack.Pop().BigInt()
x := v.estack.Pop().BigInt()
v.estack.PushVal(a.Cmp(x) <= 0 && x.Cmp(b) == -1)
case INC:
x := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Add(x, big.NewInt(1)))
case DEC:
x := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Sub(x, big.NewInt(1)))
case SIGN:
x := v.estack.Pop().BigInt()
v.estack.PushVal(x.Sign())
case NEGATE:
x := v.estack.Pop().BigInt()
v.estack.PushVal(x.Neg(x))
case ABS:
x := v.estack.Pop().BigInt()
v.estack.PushVal(x.Abs(x))
case NOT:
x := v.estack.Pop().Bool()
v.estack.PushVal(!x)
case NZ:
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x := v.estack.Pop().BigInt()
v.estack.PushVal(x.Cmp(big.NewInt(0)) != 0)
// Object operations.
case NEWARRAY:
item := v.estack.Pop()
switch t := item.value.(type) {
case *StructItem:
arr := make([]StackItem, len(t.value))
copy(arr, t.value)
v.estack.PushVal(&ArrayItem{arr})
case *ArrayItem:
v.estack.PushVal(t)
default:
n := item.BigInt().Int64()
if n > MaxArraySize {
panic("too long array")
}
items := makeArrayOfFalses(int(n))
v.estack.PushVal(&ArrayItem{items})
}
case NEWSTRUCT:
item := v.estack.Pop()
switch t := item.value.(type) {
case *ArrayItem:
arr := make([]StackItem, len(t.value))
copy(arr, t.value)
v.estack.PushVal(&StructItem{arr})
case *StructItem:
v.estack.PushVal(t)
default:
n := item.BigInt().Int64()
if n > MaxArraySize {
panic("too long struct")
}
items := makeArrayOfFalses(int(n))
v.estack.PushVal(&StructItem{items})
}
case APPEND:
itemElem := v.estack.Pop()
arrElem := v.estack.Pop()
val := cloneIfStruct(itemElem.value)
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switch t := arrElem.value.(type) {
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case *ArrayItem:
arr := t.Value().([]StackItem)
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if len(arr) >= MaxArraySize {
panic("too long array")
}
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arr = append(arr, val)
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t.value = arr
case *StructItem:
arr := t.Value().([]StackItem)
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if len(arr) >= MaxArraySize {
panic("too long struct")
}
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arr = append(arr, val)
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t.value = arr
default:
panic("APPEND: not of underlying type Array")
}
case PACK:
n := int(v.estack.Pop().BigInt().Int64())
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if n < 0 || n > v.estack.Len() || n > MaxArraySize {
panic("OPACK: invalid length")
}
items := make([]StackItem, n)
for i := 0; i < n; i++ {
items[i] = v.estack.Pop().value
}
v.estack.PushVal(items)
case UNPACK:
a := v.estack.Pop().Array()
l := len(a)
for i := l - 1; i >= 0; i-- {
v.estack.PushVal(a[i])
}
v.estack.PushVal(l)
case PICKITEM:
key := v.estack.Pop()
validateMapKey(key)
obj := v.estack.Pop()
index := int(key.BigInt().Int64())
switch t := obj.value.(type) {
// Struct and Array items have their underlying value as []StackItem.
case *ArrayItem, *StructItem:
arr := t.Value().([]StackItem)
if index < 0 || index >= len(arr) {
panic("PICKITEM: invalid index")
}
item := arr[index]
v.estack.PushVal(item)
case *MapItem:
if !t.Has(key.value) {
panic("invalid key")
}
k := toMapKey(key.value)
v.estack.Push(&Element{value: t.value[k]})
default:
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arr := obj.Bytes()
if index < 0 || index >= len(arr) {
panic("PICKITEM: invalid index")
}
item := arr[index]
v.estack.PushVal(int(item))
}
case SETITEM:
item := v.estack.Pop().value
key := v.estack.Pop()
validateMapKey(key)
obj := v.estack.Pop()
switch t := obj.value.(type) {
// Struct and Array items have their underlying value as []StackItem.
case *ArrayItem, *StructItem:
arr := t.Value().([]StackItem)
index := int(key.BigInt().Int64())
if index < 0 || index >= len(arr) {
panic("SETITEM: invalid index")
}
arr[index] = item
case *MapItem:
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if !t.Has(key.value) && len(t.value) >= MaxArraySize {
panic("too big map")
}
t.Add(key.value, item)
default:
panic(fmt.Sprintf("SETITEM: invalid item type %s", t))
}
case REVERSE:
a := v.estack.Pop().Array()
if len(a) > 1 {
for i, j := 0, len(a)-1; i <= j; i, j = i+1, j-1 {
a[i], a[j] = a[j], a[i]
}
}
case REMOVE:
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key := v.estack.Pop()
validateMapKey(key)
elem := v.estack.Pop()
switch t := elem.value.(type) {
case *ArrayItem:
a := t.value
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k := int(key.BigInt().Int64())
if k < 0 || k >= len(a) {
panic("REMOVE: invalid index")
}
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a = append(a[:k], a[k+1:]...)
t.value = a
case *StructItem:
a := t.value
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k := int(key.BigInt().Int64())
if k < 0 || k >= len(a) {
panic("REMOVE: invalid index")
}
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a = append(a[:k], a[k+1:]...)
t.value = a
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case *MapItem:
m := t.value
k := toMapKey(key.value)
delete(m, k)
default:
panic("REMOVE: invalid type")
}
case ARRAYSIZE:
elem := v.estack.Pop()
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// Cause there is no native (byte) item type here, hence we need to check
// the type of the item for array size operations.
switch t := elem.Value().(type) {
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case []StackItem:
v.estack.PushVal(len(t))
case map[interface{}]StackItem:
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v.estack.PushVal(len(t))
default:
v.estack.PushVal(len(elem.Bytes()))
}
case SIZE:
elem := v.estack.Pop()
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arr := elem.Bytes()
v.estack.PushVal(len(arr))
case JMP, JMPIF, JMPIFNOT:
var (
rOffset = int16(binary.LittleEndian.Uint16(parameter))
offset = ctx.ip + int(rOffset)
)
if offset < 0 || offset > len(ctx.prog) {
panic(fmt.Sprintf("JMP: invalid offset %d ip at %d", offset, ctx.ip))
}
cond := true
if op > JMP {
cond = v.estack.Pop().Bool()
if op == JMPIFNOT {
cond = !cond
}
}
if cond {
ctx.nextip = offset
}
case CALL:
newCtx := ctx.Copy()
newCtx.rvcount = -1
v.istack.PushVal(newCtx)
err = v.execute(v.Context(), JMP, parameter)
if err != nil {
return
}
case SYSCALL:
ifunc, ok := v.interop[string(parameter)]
if !ok {
panic(fmt.Sprintf("interop hook (%q) not registered", parameter))
}
if err := ifunc.Func(v); err != nil {
panic(fmt.Sprintf("failed to invoke syscall: %s", err))
}
case APPCALL, TAILCALL:
if v.getScript == nil {
panic("no getScript callback is set up")
}
hash, err := util.Uint160DecodeBytes(parameter)
if err != nil {
panic(err)
}
script := v.getScript(hash)
if script == nil {
panic("could not find script")
}
if op == TAILCALL {
_ = v.istack.Pop()
}
v.LoadScript(script)
case RET:
oldCtx := v.istack.Pop().Value().(*Context)
rvcount := oldCtx.rvcount
oldEstack := v.estack
if rvcount > 0 && oldEstack.Len() < rvcount {
panic("missing some return elements")
}
if v.istack.Len() == 0 {
v.state = haltState
break
}
newEstack := v.Context().estack
if oldEstack != newEstack {
if rvcount < 0 {
rvcount = oldEstack.Len()
}
for i := rvcount; i > 0; i-- {
elem := oldEstack.RemoveAt(i - 1)
newEstack.Push(elem)
}
v.estack = newEstack
v.astack = v.Context().astack
}
case CHECKSIG, VERIFY:
var hashToCheck []byte
keyb := v.estack.Pop().Bytes()
signature := v.estack.Pop().Bytes()
if op == CHECKSIG {
if v.checkhash == nil {
panic("VM is not set up properly for signature checks")
}
hashToCheck = v.checkhash
} else { // VERIFY
msg := v.estack.Pop().Bytes()
hashToCheck = hash.Sha256(msg).Bytes()
}
pkey := &keys.PublicKey{}
err := pkey.DecodeBytes(keyb)
if err != nil {
panic(err.Error())
}
res := pkey.Verify(signature, hashToCheck)
v.estack.PushVal(res)
case CHECKMULTISIG:
pkeys, err := v.estack.popSigElements()
if err != nil {
panic(fmt.Sprintf("wrong parameters: %s", err.Error()))
}
sigs, err := v.estack.popSigElements()
if err != nil {
panic(fmt.Sprintf("wrong parameters: %s", err.Error()))
}
// It's ok to have more keys than there are signatures (it would
// just mean that some keys didn't sign), but not the other way around.
if len(pkeys) < len(sigs) {
panic("more signatures than there are keys")
}
if v.checkhash == nil {
panic("VM is not set up properly for signature checks")
}
sigok := true
// j counts keys and i counts signatures.
j := 0
for i := 0; sigok && j < len(pkeys) && i < len(sigs); {
pkey := &keys.PublicKey{}
err := pkey.DecodeBytes(pkeys[j])
if err != nil {
panic(err.Error())
}
// We only move to the next signature if the check was
// successful, but if it's not maybe the next key will
// fit, so we always move to the next key.
if pkey.Verify(sigs[i], v.checkhash) {
i++
}
j++
// When there are more signatures left to check than
// there are keys the check won't successed for sure.
if len(sigs)-i > len(pkeys)-j {
sigok = false
}
}
v.estack.PushVal(sigok)
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case NEWMAP:
v.estack.Push(&Element{value: NewMapItem()})
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case KEYS:
item := v.estack.Pop()
if item == nil {
panic("no argument")
}
m, ok := item.value.(*MapItem)
if !ok {
panic("not a Map")
}
arr := make([]StackItem, 0, len(m.value))
for k := range m.value {
arr = append(arr, makeStackItem(k))
}
v.estack.PushVal(arr)
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case VALUES:
item := v.estack.Pop()
if item == nil {
panic("no argument")
}
var arr []StackItem
switch t := item.value.(type) {
case *ArrayItem, *StructItem:
src := t.Value().([]StackItem)
arr = make([]StackItem, len(src))
for i := range src {
arr[i] = cloneIfStruct(src[i])
}
case *MapItem:
arr = make([]StackItem, 0, len(t.value))
for k := range t.value {
arr = append(arr, cloneIfStruct(t.value[k]))
}
default:
panic("not a Map, Array or Struct")
}
v.estack.PushVal(arr)
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case HASKEY:
key := v.estack.Pop()
validateMapKey(key)
c := v.estack.Pop()
if c == nil {
panic("no value found")
}
switch t := c.value.(type) {
case *ArrayItem, *StructItem:
index := key.BigInt().Int64()
if index < 0 {
panic("negative index")
}
v.estack.PushVal(index < int64(len(c.Array())))
case *MapItem:
v.estack.PushVal(t.Has(key.value))
default:
panic("wrong collection type")
}
// Cryptographic operations.
case SHA1:
b := v.estack.Pop().Bytes()
sha := sha1.New()
sha.Write(b)
v.estack.PushVal(sha.Sum(nil))
case SHA256:
b := v.estack.Pop().Bytes()
v.estack.PushVal(hash.Sha256(b).Bytes())
case HASH160:
b := v.estack.Pop().Bytes()
v.estack.PushVal(hash.Hash160(b).Bytes())
case HASH256:
b := v.estack.Pop().Bytes()
v.estack.PushVal(hash.DoubleSha256(b).Bytes())
case NOP:
// unlucky ^^
case CALLI, CALLE, CALLED, CALLET, CALLEDT:
var (
tailCall = (op == CALLET || op == CALLEDT)
hashOnStack = (op == CALLED || op == CALLEDT)
addElement int
newCtx *Context
)
if hashOnStack {
addElement = 1
}
rvcount := int(parameter[0])
pcount := int(parameter[1])
if v.estack.Len() < pcount+addElement {
panic("missing some parameters")
}
if tailCall && ctx.rvcount != rvcount {
panic("context and parameter rvcount mismatch")
}
if op == CALLI {
newCtx = ctx.Copy()
} else {
var hashBytes []byte
if hashOnStack {
hashBytes = v.estack.Pop().Bytes()
} else {
hashBytes = parameter[2:]
}
hash, err := util.Uint160DecodeBytes(hashBytes)
if err != nil {
panic(err)
}
script := v.getScript(hash)
if script == nil {
panic(fmt.Sprintf("could not find script %s", hash))
}
newCtx = NewContext(script)
}
newCtx.rvcount = rvcount
newCtx.estack = NewStack("evaluation")
newCtx.astack = NewStack("alt")
// Going backwards to naturally push things onto the new stack.
for i := pcount; i > 0; i-- {
elem := v.estack.RemoveAt(i - 1)
newCtx.estack.Push(elem)
}
if tailCall {
_ = v.istack.Pop()
}
v.istack.PushVal(newCtx)
v.estack = newCtx.estack
v.astack = newCtx.astack
if op == CALLI {
err = v.execute(v.Context(), JMP, parameter[2:])
if err != nil {
return
}
}
case THROW:
panic("THROW")
case THROWIFNOT:
if !v.estack.Pop().Bool() {
panic("THROWIFNOT")
}
default:
panic(fmt.Sprintf("unknown opcode %s", op.String()))
}
return
}
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func cloneIfStruct(item StackItem) StackItem {
switch it := item.(type) {
case *StructItem:
return it.Clone()
default:
return it
}
}
func makeArrayOfFalses(n int) []StackItem {
items := make([]StackItem, n)
for i := range items {
items[i] = &BoolItem{false}
}
return items
}
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func validateMapKey(key *Element) {
if key == nil {
panic("no key found")
}
switch key.value.(type) {
case *ArrayItem, *StructItem, *MapItem:
panic("key can't be a collection")
}
}