package vm import ( "crypto/elliptic" "encoding/binary" "encoding/json" "errors" "fmt" "io" "math" "math/big" "os" "text/tabwriter" "unicode/utf8" "github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames" "github.com/nspcc-dev/neo-go/pkg/crypto/keys" "github.com/nspcc-dev/neo-go/pkg/encoding/bigint" "github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag" "github.com/nspcc-dev/neo-go/pkg/smartcontract/nef" "github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger" "github.com/nspcc-dev/neo-go/pkg/util" "github.com/nspcc-dev/neo-go/pkg/util/slice" "github.com/nspcc-dev/neo-go/pkg/vm/invocations" "github.com/nspcc-dev/neo-go/pkg/vm/opcode" "github.com/nspcc-dev/neo-go/pkg/vm/stackitem" "github.com/nspcc-dev/neo-go/pkg/vm/vmstate" ) type errorAtInstruct struct { ip int op opcode.Opcode err interface{} } func (e *errorAtInstruct) Error() string { return fmt.Sprintf("at instruction %d (%s): %s", e.ip, e.op, e.err) } func newError(ip int, op opcode.Opcode, err interface{}) *errorAtInstruct { return &errorAtInstruct{ip: ip, op: op, err: err} } // StateMessage is a vm state message which could be used as an additional info, for example by cli. type StateMessage string const ( // MaxInvocationStackSize is the maximum size of an invocation stack. MaxInvocationStackSize = 1024 // MaxTryNestingDepth is the maximum level of TRY nesting allowed, // that is you can't have more exception handling contexts than this. MaxTryNestingDepth = 16 // MaxStackSize is the maximum number of items allowed to be // on all stacks at once. MaxStackSize = 2 * 1024 maxSHLArg = stackitem.MaxBigIntegerSizeBits ) // SyscallHandler is a type for syscall handler. type SyscallHandler = func(*VM, uint32) error // VM represents the virtual machine. type VM struct { state vmstate.State // callback to get interop price getPrice func(opcode.Opcode, []byte) int64 istack []*Context // invocation stack. estack *Stack // execution stack. uncaughtException stackitem.Item // exception being handled refs refCounter gasConsumed int64 GasLimit int64 // SyscallHandler handles SYSCALL opcode. SyscallHandler func(v *VM, id uint32) error // LoadToken handles CALLT opcode. LoadToken func(id int32) error trigger trigger.Type // invTree is a top-level invocation tree (if enabled). invTree *invocations.Tree } var ( bigMinusOne = big.NewInt(-1) bigZero = big.NewInt(0) bigOne = big.NewInt(1) bigTwo = big.NewInt(2) ) // New returns a new VM object ready to load AVM bytecode scripts. func New() *VM { return NewWithTrigger(trigger.Application) } // NewWithTrigger returns a new VM for executions triggered by t. func NewWithTrigger(t trigger.Type) *VM { vm := &VM{ state: vmstate.None, trigger: t, } vm.istack = make([]*Context, 0, 8) // Most of invocations use one-two contracts, but they're likely to have internal calls. vm.estack = newStack("evaluation", &vm.refs) return vm } // SetPriceGetter registers the given PriceGetterFunc in v. // f accepts vm's Context, current instruction and instruction parameter. func (v *VM) SetPriceGetter(f func(opcode.Opcode, []byte) int64) { v.getPrice = f } // Reset allows to reuse existing VM for subsequent executions making them somewhat // more efficient. It reuses invocation and evaluation stacks as well as VM structure // itself. func (v *VM) Reset(t trigger.Type) { v.state = vmstate.None v.getPrice = nil v.istack = v.istack[:0] v.estack.elems = v.estack.elems[:0] v.uncaughtException = nil v.refs = 0 v.gasConsumed = 0 v.GasLimit = 0 v.SyscallHandler = nil v.LoadToken = nil v.trigger = t v.invTree = nil } // GasConsumed returns the amount of GAS consumed during execution. func (v *VM) GasConsumed() int64 { return v.gasConsumed } // AddGas consumes the specified amount of gas. It returns true if gas limit wasn't exceeded. func (v *VM) AddGas(gas int64) bool { v.gasConsumed += gas return v.GasLimit < 0 || v.gasConsumed <= v.GasLimit } // Estack returns the evaluation stack, so interop hooks can utilize this. func (v *VM) Estack() *Stack { return v.estack } // Istack returns the invocation stack, so interop hooks can utilize this. func (v *VM) Istack() []*Context { return v.istack } // PrintOps prints the opcodes of the current loaded program to stdout. func (v *VM) PrintOps(out io.Writer) { if out == nil { out = os.Stdout } w := tabwriter.NewWriter(out, 0, 0, 4, ' ', 0) fmt.Fprintln(w, "INDEX\tOPCODE\tPARAMETER") realctx := v.Context() ctx := &Context{sc: realctx.sc} for { cursor := "" instr, parameter, err := ctx.Next() if ctx.ip == realctx.ip { cursor = "\t<<" } if err != nil { fmt.Fprintf(w, "%d\t%s\tERROR: %s%s\n", ctx.ip, instr, err, cursor) break } var desc = "" if parameter != nil { switch instr { case opcode.JMP, opcode.JMPIF, opcode.JMPIFNOT, opcode.CALL, opcode.JMPEQ, opcode.JMPNE, opcode.JMPGT, opcode.JMPGE, opcode.JMPLE, opcode.JMPLT, opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL, opcode.CALLL, opcode.JMPEQL, opcode.JMPNEL, opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLEL, opcode.JMPLTL, opcode.PUSHA, opcode.ENDTRY, opcode.ENDTRYL: desc = getOffsetDesc(ctx, parameter) case opcode.TRY, opcode.TRYL: catchP, finallyP := getTryParams(instr, parameter) desc = fmt.Sprintf("catch %s, finally %s", getOffsetDesc(ctx, catchP), getOffsetDesc(ctx, finallyP)) case opcode.INITSSLOT: desc = fmt.Sprint(parameter[0]) case opcode.CONVERT, opcode.ISTYPE: typ := stackitem.Type(parameter[0]) desc = fmt.Sprintf("%s (%x)", typ, parameter[0]) case opcode.INITSLOT: desc = fmt.Sprintf("%d local, %d arg", parameter[0], parameter[1]) case opcode.SYSCALL: name, err := interopnames.FromID(GetInteropID(parameter)) if err != nil { name = "not found" } desc = fmt.Sprintf("%s (%x)", name, parameter) case opcode.PUSHINT8, opcode.PUSHINT16, opcode.PUSHINT32, opcode.PUSHINT64, opcode.PUSHINT128, opcode.PUSHINT256: val := bigint.FromBytes(parameter) desc = fmt.Sprintf("%d (%x)", val, parameter) case opcode.LDLOC, opcode.STLOC, opcode.LDARG, opcode.STARG, opcode.LDSFLD, opcode.STSFLD: desc = fmt.Sprintf("%d (%x)", parameter[0], 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%s\n", ctx.ip, instr, desc, cursor) if ctx.nextip >= len(ctx.sc.prog) { break } } w.Flush() } func getOffsetDesc(ctx *Context, parameter []byte) string { offset, rOffset, err := calcJumpOffset(ctx, parameter) if err != nil { return fmt.Sprintf("ERROR: %v", err) } return fmt.Sprintf("%d (%d/%x)", offset, rOffset, parameter) } // AddBreakPoint adds a breakpoint to the current context. func (v *VM) AddBreakPoint(n int) { ctx := v.Context() ctx.sc.breakPoints = append(ctx.sc.breakPoints, n) } // AddBreakPointRel adds a breakpoint relative to the current // instruction pointer. func (v *VM) AddBreakPointRel(n int) { ctx := v.Context() v.AddBreakPoint(ctx.nextip + n) } // LoadFileWithFlags loads a program in NEF format from the given path, ready to execute it. func (v *VM) LoadFileWithFlags(path string, f callflag.CallFlag) error { b, err := os.ReadFile(path) if err != nil { return err } nef, err := nef.FileFromBytes(b) if err != nil { return err } v.LoadWithFlags(nef.Script, f) return nil } // CollectInvocationTree enables collecting invocation tree data. func (v *VM) EnableInvocationTree() { v.invTree = &invocations.Tree{} } // GetInvocationTree returns the current invocation tree structure. func (v *VM) GetInvocationTree() *invocations.Tree { return v.invTree } // Load initializes the VM with the program given. func (v *VM) Load(prog []byte) { v.LoadWithFlags(prog, callflag.NoneFlag) } // LoadWithFlags initializes the VM with the program and flags given. func (v *VM) LoadWithFlags(prog []byte, f callflag.CallFlag) { // Clear all stacks and state, it could be a reload. v.istack = v.istack[:0] v.estack.Clear() v.state = vmstate.None v.gasConsumed = 0 v.invTree = nil v.LoadScriptWithFlags(prog, f) } // 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) { v.LoadScriptWithFlags(b, callflag.NoneFlag) } // LoadScriptWithFlags loads script and sets call flag to f. func (v *VM) LoadScriptWithFlags(b []byte, f callflag.CallFlag) { v.loadScriptWithCallingHash(b, nil, v.GetCurrentScriptHash(), util.Uint160{}, f, -1, 0, nil) } // LoadDynamicScript loads the given script with the given flags. This script is // considered to be dynamic, it can either return no value at all or return // exactly one value. func (v *VM) LoadDynamicScript(b []byte, f callflag.CallFlag) { v.loadScriptWithCallingHash(b, nil, v.GetCurrentScriptHash(), util.Uint160{}, f, -1, 0, DynamicOnUnload) } // LoadScriptWithHash is similar to the LoadScriptWithFlags method, but it also loads // the given script hash directly into the Context to avoid its recalculations and to make // it possible to override it for deployed contracts with special hashes (the function // assumes that it is used for deployed contracts setting context's parameters // accordingly). It's up to the user of this function to make sure the script and hash match // each other. func (v *VM) LoadScriptWithHash(b []byte, hash util.Uint160, f callflag.CallFlag) { v.loadScriptWithCallingHash(b, nil, v.GetCurrentScriptHash(), hash, f, 1, 0, nil) } // LoadNEFMethod allows to create a context to execute a method from the NEF // file with the specified caller and executing hash, call flags, return value, // method and _initialize offsets. func (v *VM) LoadNEFMethod(exe *nef.File, caller util.Uint160, hash util.Uint160, f callflag.CallFlag, hasReturn bool, methodOff int, initOff int, onContextUnload ContextUnloadCallback) { var rvcount int if hasReturn { rvcount = 1 } v.loadScriptWithCallingHash(exe.Script, exe, caller, hash, f, rvcount, methodOff, onContextUnload) if initOff >= 0 { v.Call(initOff) } } // loadScriptWithCallingHash is similar to LoadScriptWithHash but sets calling hash explicitly. // It should be used for calling from native contracts. func (v *VM) loadScriptWithCallingHash(b []byte, exe *nef.File, caller util.Uint160, hash util.Uint160, f callflag.CallFlag, rvcount int, offset int, onContextUnload ContextUnloadCallback) { v.checkInvocationStackSize() ctx := NewContextWithParams(b, rvcount, offset) parent := v.Context() if parent != nil { ctx.sc.callingContext = parent.sc parent.sc.estack = v.estack } if rvcount != -1 || v.estack.Len() != 0 { v.estack = subStack(v.estack) } ctx.sc.estack = v.estack initStack(&ctx.tryStack, "exception", nil) ctx.sc.callFlag = f ctx.sc.scriptHash = hash ctx.sc.callingScriptHash = caller ctx.sc.NEF = exe if v.invTree != nil { curTree := v.invTree if parent != nil { curTree = parent.sc.invTree } newTree := &invocations.Tree{Current: ctx.ScriptHash()} curTree.Calls = append(curTree.Calls, newTree) ctx.sc.invTree = newTree } ctx.sc.onUnload = onContextUnload v.istack = append(v.istack, 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 len(v.istack) == 0 { return nil } return v.istack[len(v.istack)-1] } // PopResult is used to pop the first item of the evaluation stack. This allows // us to test the compiler and the vm in a bi-directional way. func (v *VM) PopResult() interface{} { if v.estack.Len() == 0 { return nil } return v.estack.Pop().Value() } // DumpIStack returns json formatted representation of the invocation stack. func (v *VM) DumpIStack() string { b, _ := json.MarshalIndent(v.istack, "", " ") return string(b) } // DumpEStack returns json formatted representation of the execution stack. func (v *VM) DumpEStack() string { return dumpStack(v.estack) } // dumpStack returns json formatted representation of the given stack. func dumpStack(s *Stack) string { b, _ := json.MarshalIndent(s, "", " ") return string(b) } // State returns the state for the VM. func (v *VM) State() vmstate.State { return v.state } // Ready returns true if the VM is ready to execute the loaded program. // It will return false if no program is loaded. func (v *VM) Ready() bool { return len(v.istack) > 0 } // Run starts execution of the loaded program. func (v *VM) Run() error { var ctx *Context if !v.Ready() { v.state = vmstate.Fault return errors.New("no program loaded") } if v.state.HasFlag(vmstate.Fault) { // 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") } // vmstate.Halt (the default) or vmstate.Break are safe to continue. v.state = vmstate.None ctx = v.Context() for { switch { case v.state.HasFlag(vmstate.Fault): // 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(vmstate.Halt), v.state.HasFlag(vmstate.Break): // Normal exit from this loop. return nil case v.state == vmstate.None: if err := v.step(ctx); err != nil { return err } default: v.state = vmstate.Fault return errors.New("unknown state") } // check for breakpoint before executing the next instruction ctx = v.Context() if ctx != nil && ctx.atBreakPoint() { v.state = vmstate.Break } } } // Step 1 instruction in the program. func (v *VM) Step() error { ctx := v.Context() return v.step(ctx) } // step executes one instruction in the given context. func (v *VM) step(ctx *Context) error { op, param, err := ctx.Next() if err != nil { v.state = vmstate.Fault return newError(ctx.ip, op, err) } return v.execute(ctx, op, param) } // StepInto behaves the same as “step over” in case 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 = vmstate.Halt } if v.HasStopped() { return nil } if ctx != nil && ctx.sc.prog != nil { op, param, err := ctx.Next() if err != nil { v.state = vmstate.Fault 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 = vmstate.Break } 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 == vmstate.Break { v.state = vmstate.None } expSize := len(v.istack) for v.state == vmstate.None && len(v.istack) >= expSize { err = v.StepInto() } if v.state == vmstate.None { v.state = vmstate.Break } return err } // StepOver takes the debugger to the line that will step over the given line. // If the line contains a function, the function will be executed and the result is returned without debugging each line. func (v *VM) StepOver() error { var err error if v.HasStopped() { return err } if v.state == vmstate.Break { v.state = vmstate.None } expSize := len(v.istack) for { err = v.StepInto() if !(v.state == vmstate.None && len(v.istack) > expSize) { break } } if v.state == vmstate.None { v.state = vmstate.Break } return err } // HasFailed returns whether the VM is in the failed state now. Usually, it's used to // check status after Run. func (v *VM) HasFailed() bool { return v.state.HasFlag(vmstate.Fault) } // HasStopped returns whether the VM is in the Halt or Failed state. func (v *VM) HasStopped() bool { return v.state.HasFlag(vmstate.Halt) || v.state.HasFlag(vmstate.Fault) } // HasHalted returns whether the VM is in the Halt state. func (v *VM) HasHalted() bool { return v.state.HasFlag(vmstate.Halt) } // AtBreakpoint returns whether the VM is at breakpoint. func (v *VM) AtBreakpoint() bool { return v.state.HasFlag(vmstate.Break) } // GetInteropID converts instruction parameter to an interop ID. func GetInteropID(parameter []byte) uint32 { return binary.LittleEndian.Uint32(parameter) } // execute performs an instruction cycle in the VM. Acting on the instruction (opcode). func (v *VM) execute(ctx *Context, op opcode.Opcode, 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 = vmstate.Fault err = newError(ctx.ip, op, errRecover) } else if v.refs > MaxStackSize { v.state = vmstate.Fault err = newError(ctx.ip, op, "stack is too big") } }() if v.getPrice != nil && ctx.ip < len(ctx.sc.prog) { v.gasConsumed += v.getPrice(op, parameter) if v.GasLimit >= 0 && v.gasConsumed > v.GasLimit { panic("gas limit is exceeded") } } if op <= opcode.PUSHINT256 { v.estack.PushItem(stackitem.NewBigInteger(bigint.FromBytes(parameter))) return } switch op { case opcode.PUSHM1, opcode.PUSH0, opcode.PUSH1, opcode.PUSH2, opcode.PUSH3, opcode.PUSH4, opcode.PUSH5, opcode.PUSH6, opcode.PUSH7, opcode.PUSH8, opcode.PUSH9, opcode.PUSH10, opcode.PUSH11, opcode.PUSH12, opcode.PUSH13, opcode.PUSH14, opcode.PUSH15, opcode.PUSH16: val := int(op) - int(opcode.PUSH0) v.estack.PushItem(stackitem.NewBigInteger(big.NewInt(int64(val)))) case opcode.PUSHDATA1, opcode.PUSHDATA2, opcode.PUSHDATA4: v.estack.PushItem(stackitem.NewByteArray(parameter)) case opcode.PUSHT, opcode.PUSHF: v.estack.PushItem(stackitem.NewBool(op == opcode.PUSHT)) case opcode.PUSHA: n := getJumpOffset(ctx, parameter) ptr := stackitem.NewPointerWithHash(n, ctx.sc.prog, ctx.ScriptHash()) v.estack.PushItem(ptr) case opcode.PUSHNULL: v.estack.PushItem(stackitem.Null{}) case opcode.ISNULL: _, ok := v.estack.Pop().value.(stackitem.Null) v.estack.PushItem(stackitem.Bool(ok)) case opcode.ISTYPE: res := v.estack.Pop().Item() v.estack.PushItem(stackitem.Bool(res.Type() == stackitem.Type(parameter[0]))) case opcode.CONVERT: typ := stackitem.Type(parameter[0]) item := v.estack.Pop().Item() result, err := item.Convert(typ) if err != nil { panic(err) } v.estack.PushItem(result) case opcode.INITSSLOT: if parameter[0] == 0 { panic("zero argument") } ctx.sc.static.init(int(parameter[0]), &v.refs) case opcode.INITSLOT: if ctx.local != nil || ctx.arguments != nil { panic("already initialized") } if parameter[0] == 0 && parameter[1] == 0 { panic("zero argument") } if parameter[0] > 0 { ctx.local.init(int(parameter[0]), &v.refs) } if parameter[1] > 0 { sz := int(parameter[1]) ctx.arguments.init(sz, &v.refs) for i := 0; i < sz; i++ { ctx.arguments.Set(i, v.estack.Pop().Item(), &v.refs) } } case opcode.LDSFLD0, opcode.LDSFLD1, opcode.LDSFLD2, opcode.LDSFLD3, opcode.LDSFLD4, opcode.LDSFLD5, opcode.LDSFLD6: item := ctx.sc.static.Get(int(op - opcode.LDSFLD0)) v.estack.PushItem(item) case opcode.LDSFLD: item := ctx.sc.static.Get(int(parameter[0])) v.estack.PushItem(item) case opcode.STSFLD0, opcode.STSFLD1, opcode.STSFLD2, opcode.STSFLD3, opcode.STSFLD4, opcode.STSFLD5, opcode.STSFLD6: item := v.estack.Pop().Item() ctx.sc.static.Set(int(op-opcode.STSFLD0), item, &v.refs) case opcode.STSFLD: item := v.estack.Pop().Item() ctx.sc.static.Set(int(parameter[0]), item, &v.refs) case opcode.LDLOC0, opcode.LDLOC1, opcode.LDLOC2, opcode.LDLOC3, opcode.LDLOC4, opcode.LDLOC5, opcode.LDLOC6: item := ctx.local.Get(int(op - opcode.LDLOC0)) v.estack.PushItem(item) case opcode.LDLOC: item := ctx.local.Get(int(parameter[0])) v.estack.PushItem(item) case opcode.STLOC0, opcode.STLOC1, opcode.STLOC2, opcode.STLOC3, opcode.STLOC4, opcode.STLOC5, opcode.STLOC6: item := v.estack.Pop().Item() ctx.local.Set(int(op-opcode.STLOC0), item, &v.refs) case opcode.STLOC: item := v.estack.Pop().Item() ctx.local.Set(int(parameter[0]), item, &v.refs) case opcode.LDARG0, opcode.LDARG1, opcode.LDARG2, opcode.LDARG3, opcode.LDARG4, opcode.LDARG5, opcode.LDARG6: item := ctx.arguments.Get(int(op - opcode.LDARG0)) v.estack.PushItem(item) case opcode.LDARG: item := ctx.arguments.Get(int(parameter[0])) v.estack.PushItem(item) case opcode.STARG0, opcode.STARG1, opcode.STARG2, opcode.STARG3, opcode.STARG4, opcode.STARG5, opcode.STARG6: item := v.estack.Pop().Item() ctx.arguments.Set(int(op-opcode.STARG0), item, &v.refs) case opcode.STARG: item := v.estack.Pop().Item() ctx.arguments.Set(int(parameter[0]), item, &v.refs) case opcode.NEWBUFFER: n := toInt(v.estack.Pop().BigInt()) if n < 0 || n > stackitem.MaxSize { panic("invalid size") } v.estack.PushItem(stackitem.NewBuffer(make([]byte, n))) case opcode.MEMCPY: n := toInt(v.estack.Pop().BigInt()) if n < 0 { panic("invalid size") } si := toInt(v.estack.Pop().BigInt()) if si < 0 { panic("invalid source index") } src := v.estack.Pop().Bytes() if sum := si + n; sum < 0 || sum > len(src) { panic("size is too big") } di := toInt(v.estack.Pop().BigInt()) if di < 0 { panic("invalid destination index") } dst := v.estack.Pop().value.(*stackitem.Buffer).Value().([]byte) if sum := di + n; sum < 0 || sum > len(dst) { panic("size is too big") } copy(dst[di:], src[si:si+n]) case opcode.CAT: b := v.estack.Pop().Bytes() a := v.estack.Pop().Bytes() l := len(a) + len(b) if l > stackitem.MaxSize { panic(fmt.Sprintf("too big item: %d", l)) } ab := make([]byte, l) copy(ab, a) copy(ab[len(a):], b) v.estack.PushItem(stackitem.NewBuffer(ab)) case opcode.SUBSTR: l := toInt(v.estack.Pop().BigInt()) if l < 0 { panic("negative length") } o := toInt(v.estack.Pop().BigInt()) if o < 0 { panic("negative index") } s := v.estack.Pop().Bytes() last := l + o if last > len(s) { panic("invalid offset") } res := make([]byte, l) copy(res, s[o:last]) v.estack.PushItem(stackitem.NewBuffer(res)) case opcode.LEFT: l := toInt(v.estack.Pop().BigInt()) if l < 0 { panic("negative length") } s := v.estack.Pop().Bytes() if t := len(s); l > t { panic("size is too big") } res := make([]byte, l) copy(res, s[:l]) v.estack.PushItem(stackitem.NewBuffer(res)) case opcode.RIGHT: l := toInt(v.estack.Pop().BigInt()) if l < 0 { panic("negative length") } s := v.estack.Pop().Bytes() res := make([]byte, l) copy(res, s[len(s)-l:]) v.estack.PushItem(stackitem.NewBuffer(res)) case opcode.DEPTH: v.estack.PushItem(stackitem.NewBigInteger(big.NewInt(int64(v.estack.Len())))) case opcode.DROP: if v.estack.Len() < 1 { panic("stack is too small") } v.estack.Pop() case opcode.NIP: if v.estack.Len() < 2 { panic("no second element found") } _ = v.estack.RemoveAt(1) case opcode.XDROP: n := toInt(v.estack.Pop().BigInt()) if n < 0 { panic("invalid length") } if v.estack.Len() < n+1 { panic("bad index") } _ = v.estack.RemoveAt(n) case opcode.CLEAR: v.estack.Clear() case opcode.DUP: v.estack.Push(v.estack.Dup(0)) case opcode.OVER: if v.estack.Len() < 2 { panic("no second element found") } a := v.estack.Dup(1) v.estack.Push(a) case opcode.PICK: n := toInt(v.estack.Pop().BigInt()) if n < 0 { panic("negative stack item returned") } if v.estack.Len() < n+1 { panic("no nth element found") } a := v.estack.Dup(n) v.estack.Push(a) case opcode.TUCK: if v.estack.Len() < 2 { panic("too short stack to TUCK") } a := v.estack.Dup(0) v.estack.InsertAt(a, 2) case opcode.SWAP: err := v.estack.Swap(1, 0) if err != nil { panic(err.Error()) } case opcode.ROT: err := v.estack.Roll(2) if err != nil { panic(err.Error()) } case opcode.ROLL: n := toInt(v.estack.Pop().BigInt()) err := v.estack.Roll(n) if err != nil { panic(err.Error()) } case opcode.REVERSE3, opcode.REVERSE4, opcode.REVERSEN: n := 3 switch op { case opcode.REVERSE4: n = 4 case opcode.REVERSEN: n = toInt(v.estack.Pop().BigInt()) } if err := v.estack.ReverseTop(n); err != nil { panic(err.Error()) } // Bit operations. case opcode.INVERT: i := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Not(i))) case opcode.AND: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).And(b, a))) case opcode.OR: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Or(b, a))) case opcode.XOR: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Xor(b, a))) case opcode.EQUAL, opcode.NOTEQUAL: if v.estack.Len() < 2 { panic("need a pair of elements on the stack") } b := v.estack.Pop() a := v.estack.Pop() res := stackitem.Bool(a.value.Equals(b.value) == (op == opcode.EQUAL)) v.estack.PushItem(res) // Numeric operations. case opcode.SIGN: x := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(big.NewInt(int64(x.Sign())))) case opcode.ABS: x := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Abs(x))) case opcode.NEGATE: x := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Neg(x))) case opcode.INC: x := v.estack.Pop().BigInt() a := new(big.Int).Add(x, bigOne) v.estack.PushItem(stackitem.NewBigInteger(a)) case opcode.DEC: x := v.estack.Pop().BigInt() a := new(big.Int).Sub(x, bigOne) v.estack.PushItem(stackitem.NewBigInteger(a)) case opcode.ADD: a := v.estack.Pop().BigInt() b := v.estack.Pop().BigInt() c := new(big.Int).Add(a, b) v.estack.PushItem(stackitem.NewBigInteger(c)) case opcode.SUB: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() c := new(big.Int).Sub(a, b) v.estack.PushItem(stackitem.NewBigInteger(c)) case opcode.MUL: a := v.estack.Pop().BigInt() b := v.estack.Pop().BigInt() c := new(big.Int).Mul(a, b) v.estack.PushItem(stackitem.NewBigInteger(c)) case opcode.DIV: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Quo(a, b))) case opcode.MOD: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Rem(a, b))) case opcode.POW: exp := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() if ei := exp.Uint64(); !exp.IsUint64() || ei > maxSHLArg { panic("invalid exponent") } v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Exp(a, exp, nil))) case opcode.SQRT: a := v.estack.Pop().BigInt() if a.Sign() == -1 { panic("negative value") } v.estack.PushItem(stackitem.NewBigInteger(new(big.Int).Sqrt(a))) case opcode.MODMUL: modulus := v.estack.Pop().BigInt() if modulus.Sign() == 0 { panic("zero modulus") } x2 := v.estack.Pop().BigInt() x1 := v.estack.Pop().BigInt() res := new(big.Int).Mul(x1, x2) v.estack.PushItem(stackitem.NewBigInteger(res.Mod(res, modulus))) case opcode.MODPOW: modulus := v.estack.Pop().BigInt() exponent := v.estack.Pop().BigInt() base := v.estack.Pop().BigInt() res := new(big.Int) switch exponent.Cmp(bigMinusOne) { case -1: panic("exponent should be >= -1") case 0: if base.Cmp(bigZero) <= 0 { panic("invalid base") } if modulus.Cmp(bigTwo) < 0 { panic("invalid modulus") } if res.ModInverse(base, modulus) == nil { panic("base and modulus are not relatively prime") } case 1: if modulus.Sign() == 0 { panic("zero modulus") // https://docs.microsoft.com/en-us/dotnet/api/system.numerics.biginteger.modpow?view=net-6.0#exceptions } res.Exp(base, exponent, modulus) } v.estack.PushItem(stackitem.NewBigInteger(res)) case opcode.SHL, opcode.SHR: b := toInt(v.estack.Pop().BigInt()) if b == 0 { return } else if b < 0 || b > maxSHLArg { panic(fmt.Sprintf("operand must be between %d and %d", 0, maxSHLArg)) } a := v.estack.Pop().BigInt() var item big.Int if op == opcode.SHL { item.Lsh(a, uint(b)) } else { item.Rsh(a, uint(b)) } v.estack.PushItem(stackitem.NewBigInteger(&item)) case opcode.NOT: x := v.estack.Pop().Bool() v.estack.PushItem(stackitem.Bool(!x)) case opcode.BOOLAND: b := v.estack.Pop().Bool() a := v.estack.Pop().Bool() v.estack.PushItem(stackitem.Bool(a && b)) case opcode.BOOLOR: b := v.estack.Pop().Bool() a := v.estack.Pop().Bool() v.estack.PushItem(stackitem.Bool(a || b)) case opcode.NZ: x := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.Bool(x.Sign() != 0)) case opcode.NUMEQUAL: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.Bool(a.Cmp(b) == 0)) case opcode.NUMNOTEQUAL: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.Bool(a.Cmp(b) != 0)) case opcode.LT, opcode.LE, opcode.GT, opcode.GE: eb := v.estack.Pop() ea := v.estack.Pop() _, aNil := ea.Item().(stackitem.Null) _, bNil := eb.Item().(stackitem.Null) res := !aNil && !bNil if res { cmp := ea.BigInt().Cmp(eb.BigInt()) switch op { case opcode.LT: res = cmp == -1 case opcode.LE: res = cmp <= 0 case opcode.GT: res = cmp == 1 case opcode.GE: res = cmp >= 0 } } v.estack.PushItem(stackitem.Bool(res)) case opcode.MIN: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() val := a if a.Cmp(b) == 1 { val = b } v.estack.PushItem(stackitem.NewBigInteger(val)) case opcode.MAX: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() val := a if a.Cmp(b) == -1 { val = b } v.estack.PushItem(stackitem.NewBigInteger(val)) case opcode.WITHIN: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() x := v.estack.Pop().BigInt() v.estack.PushItem(stackitem.Bool(a.Cmp(x) <= 0 && x.Cmp(b) == -1)) // Object operations case opcode.NEWARRAY0: v.estack.PushItem(stackitem.NewArray([]stackitem.Item{})) case opcode.NEWARRAY, opcode.NEWARRAYT, opcode.NEWSTRUCT: n := toInt(v.estack.Pop().BigInt()) if n < 0 || n > MaxStackSize { panic("wrong number of elements") } typ := stackitem.AnyT if op == opcode.NEWARRAYT { typ = stackitem.Type(parameter[0]) } items := makeArrayOfType(int(n), typ) var res stackitem.Item if op == opcode.NEWSTRUCT { res = stackitem.NewStruct(items) } else { res = stackitem.NewArray(items) } v.estack.PushItem(res) case opcode.NEWSTRUCT0: v.estack.PushItem(stackitem.NewStruct([]stackitem.Item{})) case opcode.APPEND: itemElem := v.estack.Pop() arrElem := v.estack.Pop() val := cloneIfStruct(itemElem.value) switch t := arrElem.value.(type) { case *stackitem.Array: t.Append(val) case *stackitem.Struct: t.Append(val) default: panic("APPEND: not of underlying type Array") } v.refs.Add(val) case opcode.PACKMAP: n := toInt(v.estack.Pop().BigInt()) if n < 0 || n*2 > v.estack.Len() { panic("invalid length") } items := make([]stackitem.MapElement, n) for i := 0; i < n; i++ { key := v.estack.Pop() validateMapKey(key) val := v.estack.Pop().value items[i].Key = key.value items[i].Value = val } v.estack.PushItem(stackitem.NewMapWithValue(items)) case opcode.PACKSTRUCT, opcode.PACK: n := toInt(v.estack.Pop().BigInt()) if n < 0 || n > v.estack.Len() { panic("OPACK: invalid length") } items := make([]stackitem.Item, n) for i := 0; i < n; i++ { items[i] = v.estack.Pop().value } var res stackitem.Item if op == opcode.PACK { res = stackitem.NewArray(items) } else { res = stackitem.NewStruct(items) } v.estack.PushItem(res) case opcode.UNPACK: e := v.estack.Pop() var arr []stackitem.Item var l int switch t := e.value.(type) { case *stackitem.Array: arr = t.Value().([]stackitem.Item) case *stackitem.Struct: arr = t.Value().([]stackitem.Item) case *stackitem.Map: m := t.Value().([]stackitem.MapElement) l = len(m) for i := l - 1; i >= 0; i-- { v.estack.PushItem(m[i].Value) v.estack.PushItem(m[i].Key) } default: panic("element is not an array/struct/map") } if arr != nil { l = len(arr) for i := l - 1; i >= 0; i-- { v.estack.PushItem(arr[i]) } } v.estack.PushItem(stackitem.NewBigInteger(big.NewInt(int64(l)))) case opcode.PICKITEM: key := v.estack.Pop() validateMapKey(key) obj := v.estack.Pop() switch t := obj.value.(type) { // Struct and Array items have their underlying value as []Item. case *stackitem.Array, *stackitem.Struct: index := toInt(key.BigInt()) arr := t.Value().([]stackitem.Item) if index < 0 || index >= len(arr) { msg := fmt.Sprintf("The value %d is out of range.", index) v.throw(stackitem.NewByteArray([]byte(msg))) return } item := arr[index].Dup() v.estack.PushItem(item) case *stackitem.Map: index := t.Index(key.Item()) if index < 0 { v.throw(stackitem.NewByteArray([]byte("Key not found in Map"))) return } v.estack.PushItem(t.Value().([]stackitem.MapElement)[index].Value.Dup()) default: index := toInt(key.BigInt()) arr := obj.Bytes() if index < 0 || index >= len(arr) { msg := fmt.Sprintf("The value %d is out of range.", index) v.throw(stackitem.NewByteArray([]byte(msg))) return } item := arr[index] v.estack.PushItem(stackitem.NewBigInteger(big.NewInt(int64(item)))) } case opcode.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 []Item. case *stackitem.Array, *stackitem.Struct: arr := t.Value().([]stackitem.Item) index := toInt(key.BigInt()) if index < 0 || index >= len(arr) { msg := fmt.Sprintf("The value %d is out of range.", index) v.throw(stackitem.NewByteArray([]byte(msg))) return } if t.(stackitem.Immutable).IsReadOnly() { panic(stackitem.ErrReadOnly) } v.refs.Remove(arr[index]) arr[index] = item v.refs.Add(arr[index]) case *stackitem.Map: if t.IsReadOnly() { panic(stackitem.ErrReadOnly) } if i := t.Index(key.value); i >= 0 { v.refs.Remove(t.Value().([]stackitem.MapElement)[i].Value) } else { v.refs.Add(key.value) } t.Add(key.value, item) v.refs.Add(item) case *stackitem.Buffer: index := toInt(key.BigInt()) if index < 0 || index >= t.Len() { msg := fmt.Sprintf("The value %d is out of range.", index) v.throw(stackitem.NewByteArray([]byte(msg))) return } bi, err := item.TryInteger() b := toInt(bi) if err != nil || b < math.MinInt8 || b > math.MaxUint8 { panic("invalid value") } t.Value().([]byte)[index] = byte(b) default: panic(fmt.Sprintf("SETITEM: invalid item type %s", t)) } case opcode.REVERSEITEMS: item := v.estack.Pop() switch t := item.value.(type) { case *stackitem.Array, *stackitem.Struct: if t.(stackitem.Immutable).IsReadOnly() { panic(stackitem.ErrReadOnly) } a := t.Value().([]stackitem.Item) for i, j := 0, len(a)-1; i < j; i, j = i+1, j-1 { a[i], a[j] = a[j], a[i] } case *stackitem.Buffer: b := t.Value().([]byte) slice.Reverse(b) default: panic(fmt.Sprintf("invalid item type %s", t)) } case opcode.REMOVE: key := v.estack.Pop() validateMapKey(key) elem := v.estack.Pop() switch t := elem.value.(type) { case *stackitem.Array: a := t.Value().([]stackitem.Item) k := toInt(key.BigInt()) if k < 0 || k >= len(a) { panic("REMOVE: invalid index") } toRemove := a[k] t.Remove(k) v.refs.Remove(toRemove) case *stackitem.Struct: a := t.Value().([]stackitem.Item) k := toInt(key.BigInt()) if k < 0 || k >= len(a) { panic("REMOVE: invalid index") } toRemove := a[k] t.Remove(k) v.refs.Remove(toRemove) case *stackitem.Map: index := t.Index(key.Item()) // NEO 2.0 doesn't error on missing key. if index >= 0 { elems := t.Value().([]stackitem.MapElement) key := elems[index].Key val := elems[index].Value t.Drop(index) v.refs.Remove(key) v.refs.Remove(val) } default: panic("REMOVE: invalid type") } case opcode.CLEARITEMS: elem := v.estack.Pop() switch t := elem.value.(type) { case *stackitem.Array: if t.IsReadOnly() { panic(stackitem.ErrReadOnly) } for _, item := range t.Value().([]stackitem.Item) { v.refs.Remove(item) } t.Clear() case *stackitem.Struct: if t.IsReadOnly() { panic(stackitem.ErrReadOnly) } for _, item := range t.Value().([]stackitem.Item) { v.refs.Remove(item) } t.Clear() case *stackitem.Map: if t.IsReadOnly() { panic(stackitem.ErrReadOnly) } elems := t.Value().([]stackitem.MapElement) for i := range elems { v.refs.Remove(elems[i].Key) v.refs.Remove(elems[i].Value) } t.Clear() default: panic("CLEARITEMS: invalid type") } case opcode.POPITEM: arr := v.estack.Pop().Item() elems := arr.Value().([]stackitem.Item) index := len(elems) - 1 elem := elems[index] v.estack.PushItem(elem) // push item on stack firstly, to match the reference behaviour. switch item := arr.(type) { case *stackitem.Array: item.Remove(index) case *stackitem.Struct: item.Remove(index) } v.refs.Remove(elem) case opcode.SIZE: elem := v.estack.Pop() var res int // Cause there is no native (byte) item type here, we need to check // the type of the item for array size operations. switch t := elem.Value().(type) { case []stackitem.Item: res = len(t) case []stackitem.MapElement: res = len(t) default: res = len(elem.Bytes()) } v.estack.PushItem(stackitem.NewBigInteger(big.NewInt(int64(res)))) case opcode.JMP, opcode.JMPL, opcode.JMPIF, opcode.JMPIFL, opcode.JMPIFNOT, opcode.JMPIFNOTL, opcode.JMPEQ, opcode.JMPEQL, opcode.JMPNE, opcode.JMPNEL, opcode.JMPGT, opcode.JMPGTL, opcode.JMPGE, opcode.JMPGEL, opcode.JMPLT, opcode.JMPLTL, opcode.JMPLE, opcode.JMPLEL: offset := getJumpOffset(ctx, parameter) cond := true switch op { case opcode.JMP, opcode.JMPL: case opcode.JMPIF, opcode.JMPIFL, opcode.JMPIFNOT, opcode.JMPIFNOTL: cond = v.estack.Pop().Bool() == (op == opcode.JMPIF || op == opcode.JMPIFL) default: b := v.estack.Pop().BigInt() a := v.estack.Pop().BigInt() cond = getJumpCondition(op, a, b) } if cond { ctx.Jump(offset) } case opcode.CALL, opcode.CALLL: // Note: jump offset must be calculated regarding the new context, // but it is cloned and thus has the same script and instruction pointer. v.call(ctx, getJumpOffset(ctx, parameter)) case opcode.CALLA: ptr := v.estack.Pop().Item().(*stackitem.Pointer) if ptr.ScriptHash() != ctx.ScriptHash() { panic("invalid script in pointer") } v.call(ctx, ptr.Position()) case opcode.CALLT: id := int32(binary.LittleEndian.Uint16(parameter)) if err := v.LoadToken(id); err != nil { panic(err) } case opcode.SYSCALL: interopID := GetInteropID(parameter) if v.SyscallHandler == nil { panic("vm's SyscallHandler is not initialized") } err := v.SyscallHandler(v, interopID) if err != nil { iName, iErr := interopnames.FromID(interopID) if iErr == nil { panic(fmt.Sprintf("%s failed: %s", iName, err)) } panic(fmt.Sprintf("%d failed: %s", interopID, err)) } case opcode.RET: oldCtx := v.istack[len(v.istack)-1] v.istack = v.istack[:len(v.istack)-1] oldEstack := v.estack v.unloadContext(oldCtx) if len(v.istack) == 0 { v.state = vmstate.Halt break } newEstack := v.Context().sc.estack if oldEstack != newEstack { if oldCtx.retCount >= 0 && oldEstack.Len() != oldCtx.retCount { panic(fmt.Errorf("invalid return values count: expected %d, got %d", oldCtx.retCount, oldEstack.Len())) } rvcount := oldEstack.Len() for i := rvcount; i > 0; i-- { elem := oldEstack.RemoveAt(i - 1) newEstack.Push(elem) } v.estack = newEstack } case opcode.NEWMAP: v.estack.PushItem(stackitem.NewMap()) case opcode.KEYS: if v.estack.Len() == 0 { panic("no argument") } item := v.estack.Pop() m, ok := item.value.(*stackitem.Map) if !ok { panic("not a Map") } arr := make([]stackitem.Item, 0, m.Len()) for k := range m.Value().([]stackitem.MapElement) { arr = append(arr, m.Value().([]stackitem.MapElement)[k].Key.Dup()) } v.estack.PushItem(stackitem.NewArray(arr)) case opcode.VALUES: if v.estack.Len() == 0 { panic("no argument") } item := v.estack.Pop() var arr []stackitem.Item switch t := item.value.(type) { case *stackitem.Array, *stackitem.Struct: src := t.Value().([]stackitem.Item) arr = make([]stackitem.Item, len(src)) for i := range src { arr[i] = cloneIfStruct(src[i]) } case *stackitem.Map: arr = make([]stackitem.Item, 0, t.Len()) for k := range t.Value().([]stackitem.MapElement) { arr = append(arr, cloneIfStruct(t.Value().([]stackitem.MapElement)[k].Value)) } default: panic("not a Map, Array or Struct") } v.estack.PushItem(stackitem.NewArray(arr)) case opcode.HASKEY: if v.estack.Len() < 2 { panic("not enough arguments") } key := v.estack.Pop() validateMapKey(key) c := v.estack.Pop() var res bool switch t := c.value.(type) { case *stackitem.Array, *stackitem.Struct: index := toInt(key.BigInt()) if index < 0 { panic("negative index") } res = index < len(c.Array()) case *stackitem.Map: res = t.Has(key.Item()) case *stackitem.Buffer, *stackitem.ByteArray: index := toInt(key.BigInt()) if index < 0 { panic("negative index") } res = index < len(t.Value().([]byte)) default: panic("wrong collection type") } v.estack.PushItem(stackitem.Bool(res)) case opcode.NOP: // unlucky ^^ case opcode.THROW: v.throw(v.estack.Pop().Item()) case opcode.ABORT: panic("ABORT") case opcode.ASSERT: if !v.estack.Pop().Bool() { panic("ASSERT failed") } case opcode.TRY, opcode.TRYL: catchP, finallyP := getTryParams(op, parameter) if ctx.tryStack.Len() >= MaxTryNestingDepth { panic("maximum TRY depth exceeded") } cOffset := getJumpOffset(ctx, catchP) fOffset := getJumpOffset(ctx, finallyP) if cOffset == ctx.ip && fOffset == ctx.ip { panic("invalid offset for TRY*") } else if cOffset == ctx.ip { cOffset = -1 } else if fOffset == ctx.ip { fOffset = -1 } eCtx := newExceptionHandlingContext(cOffset, fOffset) ctx.tryStack.PushItem(eCtx) case opcode.ENDTRY, opcode.ENDTRYL: eCtx := ctx.tryStack.Peek(0).Value().(*exceptionHandlingContext) if eCtx.State == eFinally { panic("invalid exception handling state during ENDTRY*") } eOffset := getJumpOffset(ctx, parameter) if eCtx.HasFinally() { eCtx.State = eFinally eCtx.EndOffset = eOffset eOffset = eCtx.FinallyOffset } else { ctx.tryStack.Pop() } ctx.Jump(eOffset) case opcode.ENDFINALLY: if v.uncaughtException != nil { v.handleException() return } eCtx := ctx.tryStack.Pop().Value().(*exceptionHandlingContext) ctx.Jump(eCtx.EndOffset) default: panic(fmt.Sprintf("unknown opcode %s", op.String())) } return } func (v *VM) unloadContext(ctx *Context) { if ctx.local != nil { ctx.local.ClearRefs(&v.refs) } if ctx.arguments != nil { ctx.arguments.ClearRefs(&v.refs) } currCtx := v.Context() if currCtx == nil || ctx.sc != currCtx.sc { if ctx.sc.static != nil { ctx.sc.static.ClearRefs(&v.refs) } if ctx.sc.onUnload != nil { err := ctx.sc.onUnload(v, ctx, v.uncaughtException == nil) if err != nil { errMessage := fmt.Sprintf("context unload callback failed: %s", err) if v.uncaughtException != nil { errMessage = fmt.Sprintf("%s, uncaught exception: %s", errMessage, v.uncaughtException) } panic(errors.New(errMessage)) } } } } // getTryParams splits TRY(L) instruction parameter into offsets for catch and finally blocks. func getTryParams(op opcode.Opcode, p []byte) ([]byte, []byte) { i := 1 if op == opcode.TRYL { i = 4 } return p[:i], p[i:] } // getJumpCondition performs opcode specific comparison of a and b. func getJumpCondition(op opcode.Opcode, a, b *big.Int) bool { cmp := a.Cmp(b) switch op { case opcode.JMPEQ, opcode.JMPEQL: return cmp == 0 case opcode.JMPNE, opcode.JMPNEL: return cmp != 0 case opcode.JMPGT, opcode.JMPGTL: return cmp > 0 case opcode.JMPGE, opcode.JMPGEL: return cmp >= 0 case opcode.JMPLT, opcode.JMPLTL: return cmp < 0 case opcode.JMPLE, opcode.JMPLEL: return cmp <= 0 default: panic(fmt.Sprintf("invalid JMP* opcode: %s", op)) } } func (v *VM) throw(item stackitem.Item) { v.uncaughtException = item v.handleException() } // Call calls a method by offset using the new execution context. func (v *VM) Call(offset int) { v.call(v.Context(), offset) } // call is an internal representation of Call, which does not // affect the invocation counter and is only used by vm // package. func (v *VM) call(ctx *Context, offset int) { v.checkInvocationStackSize() newCtx := &Context{ sc: ctx.sc, retCount: -1, tryStack: ctx.tryStack, } // New context -> new exception handlers. newCtx.tryStack.elems = ctx.tryStack.elems[len(ctx.tryStack.elems):] v.istack = append(v.istack, newCtx) newCtx.Jump(offset) } // getJumpOffset returns an instruction number in the current context // to which JMP should be performed. // parameter should have length either 1 or 4 and // is interpreted as little-endian. func getJumpOffset(ctx *Context, parameter []byte) int { offset, _, err := calcJumpOffset(ctx, parameter) if err != nil { panic(err) } return offset } // calcJumpOffset returns an absolute and a relative offset of JMP/CALL/TRY instructions // either in a short (1-byte) or a long (4-byte) form. func calcJumpOffset(ctx *Context, parameter []byte) (int, int, error) { var rOffset int32 switch l := len(parameter); l { case 1: rOffset = int32(int8(parameter[0])) case 4: rOffset = int32(binary.LittleEndian.Uint32(parameter)) default: _, curr := ctx.CurrInstr() return 0, 0, fmt.Errorf("invalid %s parameter length: %d", curr, l) } offset := ctx.ip + int(rOffset) if offset < 0 || offset > len(ctx.sc.prog) { return 0, 0, fmt.Errorf("invalid offset %d ip at %d", offset, ctx.ip) } return offset, int(rOffset), nil } func (v *VM) handleException() { for pop := 0; pop < len(v.istack); pop++ { ictx := v.istack[len(v.istack)-1-pop] for j := 0; j < ictx.tryStack.Len(); j++ { e := ictx.tryStack.Peek(j) ectx := e.Value().(*exceptionHandlingContext) if ectx.State == eFinally || (ectx.State == eCatch && !ectx.HasFinally()) { ictx.tryStack.Pop() j = -1 continue } for i := 0; i < pop; i++ { ctx := v.istack[len(v.istack)-1] v.istack = v.istack[:len(v.istack)-1] v.unloadContext(ctx) } v.estack = ictx.sc.estack if ectx.State == eTry && ectx.HasCatch() { ectx.State = eCatch v.estack.PushItem(v.uncaughtException) v.uncaughtException = nil ictx.Jump(ectx.CatchOffset) } else { ectx.State = eFinally ictx.Jump(ectx.FinallyOffset) } return } } throwUnhandledException(v.uncaughtException) } // throwUnhandledException gets an exception message from the provided stackitem and panics. func throwUnhandledException(item stackitem.Item) { msg := "unhandled exception" switch item.Type() { case stackitem.ArrayT: if arr := item.Value().([]stackitem.Item); len(arr) > 0 { data, err := arr[0].TryBytes() if err == nil { msg = fmt.Sprintf("%s: %q", msg, string(data)) } } default: data, err := item.TryBytes() if err == nil { msg = fmt.Sprintf("%s: %q", msg, string(data)) } } panic(msg) } // CheckMultisigPar checks if the sigs contains sufficient valid signatures. func CheckMultisigPar(v *VM, curve elliptic.Curve, h []byte, pkeys [][]byte, sigs [][]byte) bool { if len(sigs) == 1 { return checkMultisig1(v, curve, h, pkeys, sigs[0]) } k1, k2 := 0, len(pkeys)-1 s1, s2 := 0, len(sigs)-1 type task struct { pub *keys.PublicKey signum int } type verify struct { ok bool signum int } worker := func(ch <-chan task, result chan verify) { for { t, ok := <-ch if !ok { return } result <- verify{ signum: t.signum, ok: t.pub.Verify(sigs[t.signum], h), } } } const workerCount = 3 tasks := make(chan task, 2) results := make(chan verify, len(sigs)) for i := 0; i < workerCount; i++ { go worker(tasks, results) } tasks <- task{pub: bytesToPublicKey(pkeys[k1], curve), signum: s1} tasks <- task{pub: bytesToPublicKey(pkeys[k2], curve), signum: s2} sigok := true taskCount := 2 loop: for r := range results { goingForward := true taskCount-- if r.signum == s2 { goingForward = false } if k1+1 == k2 { sigok = r.ok && s1+1 == s2 if taskCount != 0 && sigok { continue } break loop } else if r.ok { if s1+1 == s2 { if taskCount != 0 && sigok { continue } break loop } if goingForward { s1++ } else { s2-- } } var nextSig, nextKey int if goingForward { k1++ nextSig = s1 nextKey = k1 } else { k2-- nextSig = s2 nextKey = k2 } taskCount++ tasks <- task{pub: bytesToPublicKey(pkeys[nextKey], curve), signum: nextSig} } close(tasks) return sigok } func checkMultisig1(v *VM, curve elliptic.Curve, h []byte, pkeys [][]byte, sig []byte) bool { for i := range pkeys { pkey := bytesToPublicKey(pkeys[i], curve) if pkey.Verify(sig, h) { return true } } return false } func cloneIfStruct(item stackitem.Item) stackitem.Item { switch it := item.(type) { case *stackitem.Struct: ret, err := it.Clone() if err != nil { panic(err) } return ret default: return it } } func makeArrayOfType(n int, typ stackitem.Type) []stackitem.Item { if !typ.IsValid() { panic(fmt.Sprintf("invalid stack item type: %d", typ)) } items := make([]stackitem.Item, n) for i := range items { switch typ { case stackitem.BooleanT: items[i] = stackitem.NewBool(false) case stackitem.IntegerT: items[i] = stackitem.NewBigInteger(big.NewInt(0)) case stackitem.ByteArrayT: items[i] = stackitem.NewByteArray([]byte{}) default: items[i] = stackitem.Null{} } } return items } func validateMapKey(key Element) { item := key.Item() if item == nil { panic("no key found") } if err := stackitem.IsValidMapKey(item); err != nil { panic(err) } } func (v *VM) checkInvocationStackSize() { if len(v.istack) >= MaxInvocationStackSize { panic("invocation stack is too big") } } // bytesToPublicKey is a helper deserializing keys using cache and panicing on // error. func bytesToPublicKey(b []byte, curve elliptic.Curve) *keys.PublicKey { pkey, err := keys.NewPublicKeyFromBytes(b, curve) if err != nil { panic(err.Error()) } return pkey } // GetCallingScriptHash implements the ScriptHashGetter interface. func (v *VM) GetCallingScriptHash() util.Uint160 { return v.Context().sc.callingScriptHash } // GetEntryScriptHash implements the ScriptHashGetter interface. func (v *VM) GetEntryScriptHash() util.Uint160 { return v.getContextScriptHash(len(v.istack) - 1) } // GetCurrentScriptHash implements the ScriptHashGetter interface. func (v *VM) GetCurrentScriptHash() util.Uint160 { return v.getContextScriptHash(0) } // toInt converts an item to a 32-bit int. func toInt(i *big.Int) int { if !i.IsInt64() { panic("not an int32") } n := i.Int64() if n < math.MinInt32 || n > math.MaxInt32 { panic("not an int32") } return int(n) }