neoneo-go/pkg/vm/contract_checks.go

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package vm
import (
"encoding/binary"
"github.com/nspcc-dev/neo-go/pkg/vm/emit"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
)
var (
verifyInteropID = emit.InteropNameToID([]byte("Neo.Crypto.ECDsaVerify"))
multisigInteropID = emit.InteropNameToID([]byte("Neo.Crypto.ECDsaCheckMultiSig"))
)
func getNumOfThingsFromInstr(instr opcode.Opcode, param []byte) (int, bool) {
var nthings int
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switch {
case opcode.PUSH1 <= instr && instr <= opcode.PUSH16:
nthings = int(instr-opcode.PUSH1) + 1
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case instr <= opcode.PUSHINT256:
n := emit.BytesToInt(param)
if !n.IsInt64() || n.Int64() > MaxArraySize {
return 0, false
}
nthings = int(n.Int64())
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 {
_, _, ok := ParseMultiSigContract(script)
return ok
}
// ParseMultiSigContract returns number of signatures and list of public keys
// from the verification script of the contract.
func ParseMultiSigContract(script []byte) (int, [][]byte, bool) {
var nsigs, nkeys int
ctx := NewContext(script)
instr, param, err := ctx.Next()
if err != nil {
return nsigs, nil, false
}
nsigs, ok := getNumOfThingsFromInstr(instr, param)
if !ok {
return nsigs, nil, false
}
var pubs [][]byte
for {
instr, param, err = ctx.Next()
if err != nil {
return nsigs, nil, false
}
if instr != opcode.PUSHDATA1 {
break
}
if len(param) < 33 {
return nsigs, nil, false
}
pubs = append(pubs, param)
nkeys++
if nkeys > MaxArraySize {
return nsigs, nil, false
}
}
if nkeys < nsigs {
return nsigs, nil, false
}
nkeys2, ok := getNumOfThingsFromInstr(instr, param)
if !ok {
return nsigs, nil, false
}
if nkeys2 != nkeys {
return nsigs, nil, false
}
instr, _, err = ctx.Next()
if err != nil || instr != opcode.PUSHNULL {
return nsigs, nil, false
}
instr, param, err = ctx.Next()
if err != nil || instr != opcode.SYSCALL || binary.LittleEndian.Uint32(param) != multisigInteropID {
return nsigs, nil, false
}
instr, _, err = ctx.Next()
if err != nil || instr != opcode.RET || ctx.ip != len(script) {
return nsigs, nil, false
}
return nsigs, pubs, true
}
// IsSignatureContract checks whether the passed script is a signature check
// contract.
func IsSignatureContract(script []byte) bool {
if len(script) != 41 {
return false
}
ctx := NewContext(script)
instr, param, err := ctx.Next()
if err != nil || instr != opcode.PUSHDATA1 || len(param) != 33 {
return false
}
instr, _, err = ctx.Next()
if err != nil || instr != opcode.PUSHNULL {
return false
}
instr, param, err = ctx.Next()
if err != nil || instr != opcode.SYSCALL || binary.LittleEndian.Uint32(param) != verifyInteropID {
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)
}