// OP_CHECKMULTISIG
// OP_CHECKMULTISIGVERIFY
func execCheckMultiSig(ctx *execContext, op Opcode, _ []byte) error {
i := 1
if ctx.stack.height() < i {
return errStackItemMissing
}
kCount := int(klib.ToScriptInt(ctx.stack.top(-i)))
if kCount < 0 || kCount > numbers.MaxMultiSigKeyCount {
return errKeySigCountOutOfRange
}
ctx.opCount += kCount
if ctx.opCount > numbers.MaxOpcodeCount {
return errOpcodeCount
}
i++
iKey := i
i += kCount
if ctx.stack.height() < i {
return errStackItemMissing
}
sCount := int(klib.ToScriptInt(ctx.stack.top(-i)))
if sCount < 0 || sCount > kCount {
return errKeySigCountOutOfRange
}
i++
iSig := i
i += sCount
if ctx.stack.height() < i {
return errStackItemMissing
}
subScript := make([]byte, len(ctx.script)-ctx.separator)
copy(subScript, ctx.script[ctx.separator:])
for k := 0; k < sCount; k++ {
var err error
subScript, err = removeSig(subScript, ctx.stack.top(-(iSig + k)))
if err != nil {
return err
}
}
success := true
for success && (sCount > 0) {
pk := ctx.stack.top(-iKey)
sig := ctx.stack.top(-iSig)
err := checkKeySig(ctx.sctx, pk, sig, subScript, ctx.flags)
if err == nil {
iSig++
sCount--
}
iKey++
kCount--
// If there are more signatures left than keys left,
// then too many signatures have failed
if sCount > kCount {
success = false
}
}
// A Satoshi Bug causes CHECKMULTISIG to consume an extra item on the stack
// We first clear all the "real" arguments
stk := *ctx.stack
*ctx.stack = stk[:len(stk)-i+1]
// The dummy item is still requried
if ctx.stack.empty() {
return errStackItemMissing
}
// Now we check dummy being null when required
si := ctx.stack.pop()
if (ctx.flags&EvalFlagNullDummy) != 0 && len(si) > 0 {
return errDummyArgNotNull
}
if op == OP_CHECKMULTISIGVERIFY {
if !success {
return errSigVerify
}
} else { // OP_CHECKMULTISIG
b := klib.ScriptInt(1)
if !success {
b = 0
}
ctx.stack.push(b.Bytes())
}
return nil
}
func execStackOp(ctx *execContext, op Opcode, _ []byte) error {
switch op {
case OP_TOALTSTACK:
if ctx.stack.empty() {
return errStackItemMissing
}
ctx.altStack.push(ctx.stack.pop())
case OP_FROMALTSTACK:
if ctx.altStack.empty() {
return errStackItemMissing
}
ctx.stack.push(ctx.altStack.pop())
case OP_2DROP:
// (x1 x2 -- )
if ctx.stack.height() < 2 {
return errStackItemMissing
}
ctx.stack.pop()
ctx.stack.pop()
case OP_2DUP:
// (x1 x2 -- x1 x2 x1 x2)
if ctx.stack.height() < 2 {
return errStackItemMissing
}
si1, si2 := ctx.stack.top(-2), ctx.stack.top(-1)
ctx.stack.push(si1)
ctx.stack.push(si2)
case OP_3DUP:
// (x1 x2 x3 -- x1 x2 x3 x1 x2 x3)
if ctx.stack.height() < 3 {
return errStackItemMissing
}
si1, si2, si3 := ctx.stack.top(-3), ctx.stack.top(-2), ctx.stack.top(-1)
ctx.stack.push(si1)
ctx.stack.push(si2)
ctx.stack.push(si3)
case OP_2OVER:
// (x1 x2 x3 x4 -- x1 x2 x3 x4 x1 x2)
if ctx.stack.height() < 4 {
return errStackItemMissing
}
si1, si2 := ctx.stack.top(-4), ctx.stack.top(-3)
ctx.stack.push(si1)
ctx.stack.push(si2)
case OP_2ROT:
// (x1 x2 x3 x4 x5 x6 -- x3 x4 x5 x6 x1 x2)
if ctx.stack.height() < 6 {
return errStackItemMissing
}
s := *(ctx.stack)
l := len(s)
*(ctx.stack) = append(s[:l-6], s[l-4], s[l-3], s[l-2], s[l-1], s[l-6], s[l-5])
case OP_2SWAP:
// (x1 x2 x3 x4 -- x3 x4 x1 x2)
if ctx.stack.height() < 4 {
return errStackItemMissing
}
s := *(ctx.stack)
l := len(s)
*(ctx.stack) = append(s[:l-4], s[l-2], s[l-1], s[l-4], s[l-3])
case OP_IFDUP:
// Duplicate if true
if ctx.stack.empty() {
return errStackItemMissing
}
si := ctx.stack.top(-1)
if si.toBool() {
ctx.stack.push(si)
}
case OP_DEPTH:
// Push stack height on to stack
ctx.stack.push(intToStackItem(ctx.stack.height()))
case OP_DROP:
if ctx.stack.empty() {
return errStackItemMissing
}
ctx.stack.pop()
case OP_DUP:
// Duplicate stack top
if ctx.stack.empty() {
return errStackItemMissing
}
ctx.stack.push(ctx.stack.top(-1))
case OP_NIP:
// (x1 x2 -- x2)
if ctx.stack.height() < 2 {
return errStackItemMissing
}
s := *(ctx.stack)
l := len(s)
*ctx.stack = append(s[:l-2], s[l-1])
case OP_OVER:
// (x1 x2 -- x1 x2 x1)
if ctx.stack.height() < 2 {
return errStackItemMissing
}
s := *(ctx.stack)
ctx.stack.push(s[len(s)-2])
case OP_PICK, OP_ROLL:
// (xn ... x2 x1 x0 n - xn ... x2 x1 x0 xn)
// (xn ... x2 x1 x0 n - ... x2 x1 x0 xn)
if ctx.stack.height() < 2 {
return errStackItemMissing
}
top := ctx.stack.pop()
if klib.ScriptIntOverflow(top) {
return errScriptIntOverflow
}
n := int(klib.ToScriptInt(top))
if n < 0 || n >= ctx.stack.height() {
return errIndexOutOfRange
}
s := *(ctx.stack)
l := len(s)
si := s[l-n-1]
if op == OP_ROLL {
s = append(s[:l-n-1], s[l-n:]...)
}
*ctx.stack = append(s, si)
case OP_ROT:
// (x1 x2 x3 -- x2 x3 x1)
if ctx.stack.height() < 3 {
return errStackItemMissing
}
s := *(ctx.stack)
l := len(s)
*(ctx.stack) = append(s[:l-3], s[l-2], s[l-1], s[l-3])
case OP_SWAP:
// (x1 x2 -- x2 x1)
if ctx.stack.height() < 2 {
return errStackItemMissing
}
s := *(ctx.stack)
l := len(s)
*(ctx.stack) = append(s[:l-2], s[l-1], s[l-2])
case OP_TUCK:
// (x1 x2 -- x2 x1 x2)
if ctx.stack.height() < 2 {
return errStackItemMissing
}
s := *(ctx.stack)
l := len(s)
*(ctx.stack) = append(s[:l-2], s[l-1], s[l-2], s[l-1])
}
return nil
}