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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2022 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <pubkey.h>
#include <script/interpreter.h>
#include <script/script.h>
#include <script/solver.h>
#include <span.h>
#include <algorithm>
#include <cassert>
#include <string>
typedef std::vector<unsigned char> valtype;
std::string GetTxnOutputType(TxoutType t)
{
switch (t) {
case TxoutType::NONSTANDARD: return "nonstandard";
case TxoutType::PUBKEY: return "pubkey";
case TxoutType::PUBKEYHASH: return "pubkeyhash";
case TxoutType::SCRIPTHASH: return "scripthash";
case TxoutType::MULTISIG: return "multisig";
case TxoutType::NULL_DATA: return "nulldata";
case TxoutType::WITNESS_V0_KEYHASH: return "witness_v0_keyhash";
case TxoutType::WITNESS_V0_SCRIPTHASH: return "witness_v0_scripthash";
case TxoutType::WITNESS_V1_TAPROOT: return "witness_v1_taproot";
case TxoutType::WITNESS_UNKNOWN: return "witness_unknown";
} // no default case, so the compiler can warn about missing cases
assert(false);
}
static bool MatchPayToPubkey(const CScript& script, valtype& pubkey)
{
if (script.size() == CPubKey::SIZE + 2 && script[0] == CPubKey::SIZE && script.back() == OP_CHECKSIG) {
pubkey = valtype(script.begin() + 1, script.begin() + CPubKey::SIZE + 1);
return CPubKey::ValidSize(pubkey);
}
if (script.size() == CPubKey::COMPRESSED_SIZE + 2 && script[0] == CPubKey::COMPRESSED_SIZE && script.back() == OP_CHECKSIG) {
pubkey = valtype(script.begin() + 1, script.begin() + CPubKey::COMPRESSED_SIZE + 1);
return CPubKey::ValidSize(pubkey);
}
return false;
}
static bool MatchPayToPubkeyHash(const CScript& script, valtype& pubkeyhash)
{
if (script.size() == 25 && script[0] == OP_DUP && script[1] == OP_HASH160 && script[2] == 20 && script[23] == OP_EQUALVERIFY && script[24] == OP_CHECKSIG) {
pubkeyhash = valtype(script.begin () + 3, script.begin() + 23);
return true;
}
return false;
}
/** Test for "small positive integer" script opcodes - OP_1 through OP_16. */
static constexpr bool IsSmallInteger(opcodetype opcode)
{
return opcode >= OP_1 && opcode <= OP_16;
}
/** Retrieve a minimally-encoded number in range [min,max] from an (opcode, data) pair,
* whether it's OP_n or through a push. */
static std::optional<int> GetScriptNumber(opcodetype opcode, valtype data, int min, int max)
{
int count;
if (IsSmallInteger(opcode)) {
count = CScript::DecodeOP_N(opcode);
} else if (IsPushdataOp(opcode)) {
if (!CheckMinimalPush(data, opcode)) return {};
try {
count = CScriptNum(data, /* fRequireMinimal = */ true).getint();
} catch (const scriptnum_error&) {
return {};
}
} else {
return {};
}
if (count < min || count > max) return {};
return count;
}
static bool MatchMultisig(const CScript& script, int& required_sigs, std::vector<valtype>& pubkeys)
{
opcodetype opcode;
valtype data;
CScript::const_iterator it = script.begin();
if (script.size() < 1 || script.back() != OP_CHECKMULTISIG) return false;
if (!script.GetOp(it, opcode, data)) return false;
auto req_sigs = GetScriptNumber(opcode, data, 1, MAX_PUBKEYS_PER_MULTISIG);
if (!req_sigs) return false;
required_sigs = *req_sigs;
while (script.GetOp(it, opcode, data) && CPubKey::ValidSize(data)) {
pubkeys.emplace_back(std::move(data));
}
auto num_keys = GetScriptNumber(opcode, data, required_sigs, MAX_PUBKEYS_PER_MULTISIG);
if (!num_keys) return false;
if (pubkeys.size() != static_cast<unsigned long>(*num_keys)) return false;
return (it + 1 == script.end());
}
std::optional<std::pair<int, std::vector<Span<const unsigned char>>>> MatchMultiA(const CScript& script)
{
std::vector<Span<const unsigned char>> keyspans;
// Redundant, but very fast and selective test.
if (script.size() == 0 || script[0] != 32 || script.back() != OP_NUMEQUAL) return {};
// Parse keys
auto it = script.begin();
while (script.end() - it >= 34) {
if (*it != 32) return {};
++it;
keyspans.emplace_back(&*it, 32);
it += 32;
if (*it != (keyspans.size() == 1 ? OP_CHECKSIG : OP_CHECKSIGADD)) return {};
++it;
}
if (keyspans.size() == 0 || keyspans.size() > MAX_PUBKEYS_PER_MULTI_A) return {};
// Parse threshold.
opcodetype opcode;
std::vector<unsigned char> data;
if (!script.GetOp(it, opcode, data)) return {};
if (it == script.end()) return {};
if (*it != OP_NUMEQUAL) return {};
++it;
if (it != script.end()) return {};
auto threshold = GetScriptNumber(opcode, data, 1, (int)keyspans.size());
if (!threshold) return {};
// Construct result.
return std::pair{*threshold, std::move(keyspans)};
}
TxoutType Solver(const CScript& scriptPubKey, std::vector<std::vector<unsigned char>>& vSolutionsRet)
{
vSolutionsRet.clear();
// Shortcut for pay-to-script-hash, which are more constrained than the other types:
// it is always OP_HASH160 20 [20 byte hash] OP_EQUAL
if (scriptPubKey.IsPayToScriptHash())
{
std::vector<unsigned char> hashBytes(scriptPubKey.begin()+2, scriptPubKey.begin()+22);
vSolutionsRet.push_back(hashBytes);
return TxoutType::SCRIPTHASH;
}
int witnessversion;
std::vector<unsigned char> witnessprogram;
if (scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_KEYHASH_SIZE) {
vSolutionsRet.push_back(std::move(witnessprogram));
return TxoutType::WITNESS_V0_KEYHASH;
}
if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
vSolutionsRet.push_back(std::move(witnessprogram));
return TxoutType::WITNESS_V0_SCRIPTHASH;
}
if (witnessversion == 1 && witnessprogram.size() == WITNESS_V1_TAPROOT_SIZE) {
vSolutionsRet.push_back(std::move(witnessprogram));
return TxoutType::WITNESS_V1_TAPROOT;
}
if (witnessversion != 0) {
vSolutionsRet.push_back(std::vector<unsigned char>{(unsigned char)witnessversion});
vSolutionsRet.push_back(std::move(witnessprogram));
return TxoutType::WITNESS_UNKNOWN;
}
return TxoutType::NONSTANDARD;
}
// Provably prunable, data-carrying output
//
// So long as script passes the IsUnspendable() test and all but the first
// byte passes the IsPushOnly() test we don't care what exactly is in the
// script.
if (scriptPubKey.size() >= 1 && scriptPubKey[0] == OP_RETURN && scriptPubKey.IsPushOnly(scriptPubKey.begin()+1)) {
return TxoutType::NULL_DATA;
}
std::vector<unsigned char> data;
if (MatchPayToPubkey(scriptPubKey, data)) {
vSolutionsRet.push_back(std::move(data));
return TxoutType::PUBKEY;
}
if (MatchPayToPubkeyHash(scriptPubKey, data)) {
vSolutionsRet.push_back(std::move(data));
return TxoutType::PUBKEYHASH;
}
int required;
std::vector<std::vector<unsigned char>> keys;
if (MatchMultisig(scriptPubKey, required, keys)) {
vSolutionsRet.push_back({static_cast<unsigned char>(required)}); // safe as required is in range 1..20
vSolutionsRet.insert(vSolutionsRet.end(), keys.begin(), keys.end());
vSolutionsRet.push_back({static_cast<unsigned char>(keys.size())}); // safe as size is in range 1..20
return TxoutType::MULTISIG;
}
vSolutionsRet.clear();
return TxoutType::NONSTANDARD;
}
CScript GetScriptForRawPubKey(const CPubKey& pubKey)
{
return CScript() << std::vector<unsigned char>(pubKey.begin(), pubKey.end()) << OP_CHECKSIG;
}
CScript GetScriptForMultisig(int nRequired, const std::vector<CPubKey>& keys)
{
CScript script;
script << nRequired;
for (const CPubKey& key : keys)
script << ToByteVector(key);
script << keys.size() << OP_CHECKMULTISIG;
return script;
}
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