neo-go/pkg/vm/vm.go
2019-09-16 15:50:51 +03:00

881 lines
18 KiB
Go

package vm
import (
"crypto/sha1"
"fmt"
"io/ioutil"
"log"
"math/big"
"os"
"reflect"
"text/tabwriter"
"github.com/CityOfZion/neo-go/pkg/crypto/hash"
"github.com/CityOfZion/neo-go/pkg/util"
)
// Mode configures behaviour of the VM.
type Mode uint
// Available VM Modes.
var (
ModeMute Mode = 1 << 0
)
// VM represents the virtual machine.
type VM struct {
state State
// registered interop hooks.
interop map[string]InteropFunc
// scripts loaded in memory.
scripts map[util.Uint160][]byte
istack *Stack // invocation stack.
estack *Stack // execution stack.
astack *Stack // alt stack.
// Mute all output after execution.
mute bool
}
// New returns a new VM object ready to load .avm bytecode scripts.
func New(mode Mode) *VM {
vm := &VM{
interop: make(map[string]InteropFunc),
scripts: make(map[util.Uint160][]byte),
state: haltState,
istack: NewStack("invocation"),
estack: NewStack("evaluation"),
astack: NewStack("alt"),
}
if mode == ModeMute {
vm.mute = true
}
// Register native interop hooks.
vm.RegisterInteropFunc("Neo.Runtime.Log", runtimeLog)
vm.RegisterInteropFunc("Neo.Runtime.Notify", runtimeNotify)
return vm
}
// RegisterInteropFunc will register the given InteropFunc to the VM.
func (v *VM) RegisterInteropFunc(name string, f InteropFunc) {
v.interop[name] = f
}
// Estack will return the evaluation stack so interop hooks can utilize this.
func (v *VM) Estack() *Stack {
return v.estack
}
// Astack will return the alt stack so interop hooks can utilize this.
func (v *VM) Astack() *Stack {
return v.astack
}
// Istack will return the invocation stack so interop hooks can utilize this.
func (v *VM) Istack() *Stack {
return v.istack
}
// LoadArgs will load 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)
}
}
// PrintOps will print the opcodes of the current loaded program to stdout.
func (v *VM) PrintOps() {
prog := v.Context().Program()
w := tabwriter.NewWriter(os.Stdout, 0, 0, 4, ' ', 0)
fmt.Fprintln(w, "INDEX\tOPCODE\tDESC\t")
cursor := ""
ip, _ := v.Context().CurrInstr()
for i := 0; i < len(prog); i++ {
if i == ip {
cursor = "<<"
} else {
cursor = ""
}
fmt.Fprintf(w, "%d\t0x%2x\t%s\t%s\n", i, prog[i], Instruction(prog[i]).String(), cursor)
}
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)
}
// LoadFile will load 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, it could be a reload.
v.istack.Clear()
v.estack.Clear()
v.astack.Clear()
v.istack.PushVal(NewContext(prog))
}
// LoadScript will load 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)
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.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{} {
return v.estack.Pop().value.Value()
}
// 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)
}
// Ready return 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() {
if !v.Ready() {
fmt.Println("no program loaded")
return
}
v.state = noneState
for {
switch {
case v.state.HasFlag(haltState):
if !v.mute {
fmt.Println(v.Stack("estack"))
}
return
case v.state.HasFlag(breakState):
ctx := v.Context()
i, op := ctx.CurrInstr()
fmt.Printf("at breakpoint %d (%s)\n", i, op.String())
return
case v.state.HasFlag(faultState):
fmt.Println("FAULT")
return
case v.state == noneState:
v.Step()
}
}
}
// Step 1 instruction in the program.
func (v *VM) Step() {
ctx := v.Context()
op := ctx.Next()
v.execute(ctx, op)
// re-peek the context as it could been changed during execution.
cctx := v.Context()
if cctx != nil && cctx.atBreakPoint() {
v.state = breakState
}
}
// execute performs an instruction cycle in the VM. Acting on the instruction (opcode).
func (v *VM) execute(ctx *Context, op Instruction) {
// 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.
defer func() {
if err := recover(); err != nil {
log.Printf("error encountered at instruction %d (%s)", ctx.ip, op)
log.Println(err)
v.state = faultState
}
}()
if op >= PUSHBYTES1 && op <= PUSHBYTES75 {
b := ctx.readBytes(int(op))
if b == nil {
panic("failed to read instruction parameter")
}
v.estack.PushVal(b)
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:
n := ctx.readByte()
b := ctx.readBytes(int(n))
if b == nil {
panic("failed to read instruction parameter")
}
v.estack.PushVal(b)
case PUSHDATA2:
n := ctx.readUint16()
b := ctx.readBytes(int(n))
if b == nil {
panic("failed to read instruction parameter")
}
v.estack.PushVal(b)
case PUSHDATA4:
n := ctx.readUint32()
b := ctx.readBytes(int(n))
if b == nil {
panic("failed to read instruction parameter")
}
v.estack.PushVal(b)
// 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)
case CAT:
b := v.estack.Pop().Bytes()
a := v.estack.Pop().Bytes()
ab := append(a, b...)
v.estack.PushVal(ab)
case SUBSTR:
l := int(v.estack.Pop().BigInt().Int64())
o := int(v.estack.Pop().BigInt().Int64())
s := v.estack.Pop().Bytes()
if l < 0 {
panic("negative length")
}
if o < 0 {
panic("negative index")
}
if l+o > len(s) {
panic("out of bounds access")
}
v.estack.PushVal(s[o : o+l])
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])
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:])
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())
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:
b := v.estack.Pop()
if b == nil {
panic("no top-level element found")
}
a := v.estack.Peek(0)
if a == nil {
panic("no second element found")
}
v.estack.Push(b)
v.estack.Push(a)
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")
}
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:
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")
}
v.estack.PushVal(reflect.DeepEqual(a, b))
// Bit operations.
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:
b := v.estack.Pop().BigInt()
if b.Int64() == 0 {
return
}
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Lsh(a, uint(b.Int64())))
case SHR:
b := v.estack.Pop().BigInt()
if b.Int64() == 0 {
return
}
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Rsh(a, uint(b.Int64())))
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:
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:
v.estack.PushVal(&ArrayItem{t.value})
case *ArrayItem:
v.estack.PushVal(t)
default:
n := item.BigInt()
items := makeArrayOfFalses(int(n.Int64()))
v.estack.PushVal(&ArrayItem{items})
}
case NEWSTRUCT:
item := v.estack.Pop()
switch t := item.value.(type) {
case *ArrayItem:
v.estack.PushVal(&StructItem{t.value})
case *StructItem:
v.estack.PushVal(t)
default:
n := item.BigInt()
items := makeArrayOfFalses(int(n.Int64()))
v.estack.PushVal(&StructItem{items})
}
case APPEND:
itemElem := v.estack.Pop()
arrElem := v.estack.Pop()
switch t := arrElem.value.(type) {
case *ArrayItem:
arr := t.Value().([]StackItem)
arr = append(arr, itemElem.value)
t.value = arr
case *StructItem:
arr := t.Value().([]StackItem)
arr = append(arr, itemElem.value)
t.value = arr
default:
panic("APPEND: not of underlying type Array")
}
case PACK:
n := int(v.estack.Pop().BigInt().Int64())
if n < 0 || n > v.estack.Len() {
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:
var (
key = v.estack.Pop()
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)
default:
arr := obj.Bytes()
if index < 0 || index >= len(arr) {
panic("PICKITEM: invalid index")
}
item := arr[index]
v.estack.PushVal(int(item))
}
case SETITEM:
var (
item = v.estack.Pop().value
key = v.estack.Pop()
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("SETITEM: invalid index")
}
arr[index] = 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:
key := int(v.estack.Pop().BigInt().Int64())
elem := v.estack.Pop()
switch t := elem.value.(type) {
case *ArrayItem:
a := t.value
if key < 0 || key >= len(a) {
panic("REMOVE: invalid index")
}
a = append(a[:key], a[key+1:]...)
t.value = a
case *StructItem:
a := t.value
if key < 0 || key >= len(a) {
panic("REMOVE: invalid index")
}
a = append(a[:key], a[key+1:]...)
t.value = a
default:
panic("REMOVE: invalid type")
}
case ARRAYSIZE:
elem := v.estack.Pop()
// 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.Value().(type) {
case []StackItem:
v.estack.PushVal(len(t))
case []uint8:
v.estack.PushVal(len(t))
default:
panic("ARRAYSIZE: item not of type []StackItem")
}
case SIZE:
elem := v.estack.Pop()
arr := elem.Bytes()
v.estack.PushVal(len(arr))
case JMP, JMPIF, JMPIFNOT:
var (
rOffset = int16(ctx.readUint16())
offset = ctx.ip + int(rOffset) - 3 // sizeOf(int16 + uint8)
)
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.ip = offset
}
case CALL:
v.istack.PushVal(ctx.Copy())
ctx.ip += 2
v.execute(v.Context(), JMP)
case SYSCALL:
api := ctx.readVarBytes()
ifunc, ok := v.interop[string(api)]
if !ok {
panic(fmt.Sprintf("interop hook (%s) not registered", api))
}
if err := ifunc(v); err != nil {
panic(fmt.Sprintf("failed to invoke syscall: %s", err))
}
case APPCALL, TAILCALL:
if len(v.scripts) == 0 {
panic("script table is empty")
}
hash, err := util.Uint160DecodeBytes(ctx.readBytes(20))
if err != nil {
panic(err)
}
script, ok := v.scripts[hash]
if !ok {
panic("could not find script")
}
if op == TAILCALL {
_ = v.istack.Pop()
}
v.LoadScript(script)
case RET:
_ = v.istack.Pop()
if v.istack.Len() == 0 {
v.state = haltState
}
case CHECKSIG, VERIFY, CHECKMULTISIG, NEWMAP, HASKEY, KEYS, VALUES:
panic("unimplemented")
// 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 THROW:
panic("THROW")
case THROWIFNOT:
if !v.estack.Pop().Bool() {
panic("THROWIFNOT")
}
default:
panic(fmt.Sprintf("unknown opcode %s", op.String()))
}
}
func makeArrayOfFalses(n int) []StackItem {
items := make([]StackItem, n)
for i := range items {
items[i] = &BoolItem{false}
}
return items
}
func init() {
log.SetPrefix("NEO-GO-VM > ")
log.SetFlags(0)
}