neo-go/pkg/vm/contract_checks.go

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package vm
import (
"encoding/binary"
"github.com/CityOfZion/neo-go/pkg/vm/opcode"
)
func getNumOfThingsFromInstr(instr opcode.Opcode, param []byte) (int, bool) {
var nthings int
switch instr {
case 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:
nthings = int(instr-opcode.PUSH1) + 1
case opcode.PUSHBYTES1:
nthings = int(param[0])
case opcode.PUSHBYTES2:
nthings = int(binary.LittleEndian.Uint16(param))
default:
return 0, false
}
if nthings < 1 || nthings > MaxArraySize {
return 0, false
}
return nthings, true
}
// IsMultiSigContract checks whether the passed script is a multi-signature
// contract.
func IsMultiSigContract(script []byte) bool {
var nsigs, nkeys int
ctx := NewContext(script)
instr, param, err := ctx.Next()
if err != nil {
return false
}
nsigs, ok := getNumOfThingsFromInstr(instr, param)
if !ok {
return false
}
for {
instr, param, err = ctx.Next()
if err != nil {
return false
}
if instr != opcode.PUSHBYTES33 {
break
}
nkeys++
if nkeys > MaxArraySize {
return false
}
}
if nkeys < nsigs {
return false
}
nkeys2, ok := getNumOfThingsFromInstr(instr, param)
if !ok {
return false
}
if nkeys2 != nkeys {
return false
}
instr, _, err = ctx.Next()
if err != nil || instr != opcode.CHECKMULTISIG {
return false
}
instr, _, err = ctx.Next()
if err != nil || instr != opcode.RET || ctx.ip != len(script) {
return false
}
return true
}
// IsSignatureContract checks whether the passed script is a signature check
// contract.
func IsSignatureContract(script []byte) bool {
ctx := NewContext(script)
instr, _, err := ctx.Next()
if err != nil || instr != opcode.PUSHBYTES33 {
return false
}
instr, _, err = ctx.Next()
if err != nil || instr != opcode.CHECKSIG {
return false
}
instr, _, err = ctx.Next()
if err != nil || instr != opcode.RET || ctx.ip != len(script) {
return false
}
return true
}
// IsStandardContract checks whether the passed script is a signature or
// multi-signature contract.
func IsStandardContract(script []byte) bool {
return IsSignatureContract(script) || IsMultiSigContract(script)
}