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miniscript: restrict multi() usage to P2WSH context

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CHECKMULTISIG is disabled for Tapscript. Instead, we'll introduce
a multi_a() fragment with the same semantic as multi().
This commit is contained in:
Antoine Poinsot 2023-01-21 13:49:59 +01:00
parent 91b4db8590
commit 9164c2eca1
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GPG key ID: E13FC145CD3F4304
2 changed files with 20 additions and 2 deletions
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1
src/script/miniscript.cpp
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@ -10,6 +10,7 @@
#include <assert.h>
namespace miniscript {
namespace internal {
Type SanitizeType(Type e) {

21
src/script/miniscript.h
View file

@ -20,6 +20,7 @@
#include <primitives/transaction.h>
#include <script/script.h>
#include <span.h>
#include <util/check.h>
#include <util/spanparsing.h>
#include <util/strencodings.h>
#include <util/string.h>
@ -234,6 +235,16 @@ enum class MiniscriptContext {
TAPSCRIPT,
};
/** Whether the context Tapscript, ensuring the only other possibility is P2WSH. */
constexpr bool IsTapscript(MiniscriptContext ms_ctx)
{
switch (ms_ctx) {
case MiniscriptContext::P2WSH: return false;
case MiniscriptContext::TAPSCRIPT: return true;
}
assert(false);
}
namespace internal {
//! Helper function for Node::CalcType.
@ -585,7 +596,8 @@ public:
};
// The upward function computes for a node, given its followed-by-OP_VERIFY status
// and the CScripts of its child nodes, the CScript of the node.
auto upfn = [&ctx](bool verify, const Node& node, Span<CScript> subs) -> CScript {
const bool is_tapscript{IsTapscript(m_script_ctx)};
auto upfn = [&ctx, is_tapscript](bool verify, const Node& node, Span<CScript> subs) -> CScript {
switch (node.fragment) {
case Fragment::PK_K: return BuildScript(ctx.ToPKBytes(node.keys[0]));
case Fragment::PK_H: return BuildScript(OP_DUP, OP_HASH160, ctx.ToPKHBytes(node.keys[0]), OP_EQUALVERIFY);
@ -618,6 +630,7 @@ public:
case Fragment::OR_I: return BuildScript(OP_IF, subs[0], OP_ELSE, subs[1], OP_ENDIF);
case Fragment::ANDOR: return BuildScript(std::move(subs[0]), OP_NOTIF, subs[2], OP_ELSE, subs[1], OP_ENDIF);
case Fragment::MULTI: {
CHECK_NONFATAL(!is_tapscript);
CScript script = BuildScript(node.k);
for (const auto& key : node.keys) {
script = BuildScript(std::move(script), ctx.ToPKBytes(key));
@ -653,7 +666,8 @@ public:
};
// The upward function computes for a node, given whether its parent is a wrapper,
// and the string representations of its child nodes, the string representation of the node.
auto upfn = [&ctx](bool wrapped, const Node& node, Span<std::string> subs) -> std::optional<std::string> {
const bool is_tapscript{IsTapscript(m_script_ctx)};
auto upfn = [&ctx, is_tapscript](bool wrapped, const Node& node, Span<std::string> subs) -> std::optional<std::string> {
std::string ret = wrapped ? ":" : "";
switch (node.fragment) {
@ -717,6 +731,7 @@ public:
if (node.subs[2]->fragment == Fragment::JUST_0) return std::move(ret) + "and_n(" + std::move(subs[0]) + "," + std::move(subs[1]) + ")";
return std::move(ret) + "andor(" + std::move(subs[0]) + "," + std::move(subs[1]) + "," + std::move(subs[2]) + ")";
case Fragment::MULTI: {
CHECK_NONFATAL(!is_tapscript);
auto str = std::move(ret) + "multi(" + ::ToString(node.k);
for (const auto& key : node.keys) {
auto key_str = ctx.ToString(key);
@ -1631,6 +1646,7 @@ inline NodeRef<Key> Parse(Span<const char> in, const Ctx& ctx)
in = in.subspan(arg_size + 1);
script_size += 1 + (num > 16) + (num > 0x7f) + (num > 0x7fff) + (num > 0x7fffff);
} else if (Const("multi(", in)) {
if (IsTapscript(ctx.MsContext())) return {};
// Get threshold
int next_comma = FindNextChar(in, ',');
if (next_comma < 1) return {};
@ -1989,6 +2005,7 @@ inline NodeRef<Key> DecodeScript(I& in, I last, const Ctx& ctx)
}
// Multi
if (last - in >= 3 && in[0].first == OP_CHECKMULTISIG) {
if (IsTapscript(ctx.MsContext())) return {};
std::vector<Key> keys;
const auto n = ParseScriptNumber(in[1]);
if (!n || last - in < 3 + *n) return {};