git / moonbite-core / src/script/descriptor.cpp · raw
// Copyright (c) 2018-2020 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 <script/descriptor.h>#include <key_io.h>#include <pubkey.h>#include <script/script.h>#include <script/standard.h>#include <span.h>#include <util/bip32.h>#include <util/spanparsing.h>#include <util/system.h>#include <util/strencodings.h>#include <util/vector.h>#include <memory>#include <string>#include <vector>namespace {////////////////////////////////////////////////////////////////////////////// Checksum //////////////////////////////////////////////////////////////////////////////// This section implements a checksum algorithm for descriptors with the// following properties:// * Mistakes in a descriptor string are measured in "symbol errors". The higher// the number of symbol errors, the harder it is to detect:// * An error substituting a character from 0123456789()[],'/*abcdefgh@:$%{} for// another in that set always counts as 1 symbol error.// * Note that hex encoded keys are covered by these characters. Xprvs and// xpubs use other characters too, but already have their own checksum// mechanism.// * Function names like "multi()" use other characters, but mistakes in// these would generally result in an unparsable descriptor.// * A case error always counts as 1 symbol error.// * Any other 1 character substitution error counts as 1 or 2 symbol errors.// * Any 1 symbol error is always detected.// * Any 2 or 3 symbol error in a descriptor of up to 49154 characters is always detected.// * Any 4 symbol error in a descriptor of up to 507 characters is always detected.// * Any 5 symbol error in a descriptor of up to 77 characters is always detected.// * Is optimized to minimize the chance a 5 symbol error in a descriptor up to 387 characters is undetected// * Random errors have a chance of 1 in 2**40 of being undetected.//// These properties are achieved by expanding every group of 3 (non checksum) characters into// 4 GF(32) symbols, over which a cyclic code is defined./* * Interprets c as 8 groups of 5 bits which are the coefficients of a degree 8 polynomial over GF(32), * multiplies that polynomial by x, computes its remainder modulo a generator, and adds the constant term val. * * This generator is G(x) = x^8 + {30}x^7 + {23}x^6 + {15}x^5 + {14}x^4 + {10}x^3 + {6}x^2 + {12}x + {9}. * It is chosen to define an cyclic error detecting code which is selected by: * - Starting from all BCH codes over GF(32) of degree 8 and below, which by construction guarantee detecting * 3 errors in windows up to 19000 symbols. * - Taking all those generators, and for degree 7 ones, extend them to degree 8 by adding all degree-1 factors. * - Selecting just the set of generators that guarantee detecting 4 errors in a window of length 512. * - Selecting one of those with best worst-case behavior for 5 errors in windows of length up to 512. * * The generator and the constants to implement it can be verified using this Sage code: * B = GF(2) # Binary field * BP.<b> = B[] # Polynomials over the binary field * F_mod = b**5 + b**3 + 1 * F.<f> = GF(32, modulus=F_mod, repr='int') # GF(32) definition * FP.<x> = F[] # Polynomials over GF(32) * E_mod = x**3 + x + F.fetch_int(8) * E.<e> = F.extension(E_mod) # Extension field definition * alpha = e**2743 # Choice of an element in extension field * for p in divisors(E.order() - 1): # Verify alpha has order 32767. * assert((alpha**p == 1) == (p % 32767 == 0)) * G = lcm([(alpha**i).minpoly() for i in [1056,1057,1058]] + [x + 1]) * print(G) # Print out the generator * for i in [1,2,4,8,16]: # Print out {1,2,4,8,16}*(G mod x^8), packed in hex integers. * v = 0 * for coef in reversed((F.fetch_int(i)*(G % x**8)).coefficients(sparse=True)): * v = v*32 + coef.integer_representation() * print("0x%x" % v) */uint64_t PolyMod(uint64_t c, int val){ uint8_t c0 = c >> 35; c = ((c & 0x7ffffffff) << 5) ^ val; if (c0 & 1) c ^= 0xf5dee51989; if (c0 & 2) c ^= 0xa9fdca3312; if (c0 & 4) c ^= 0x1bab10e32d; if (c0 & 8) c ^= 0x3706b1677a; if (c0 & 16) c ^= 0x644d626ffd; return c;}std::string DescriptorChecksum(const Span<const char>& span){ /** A character set designed such that: * - The most common 'unprotected' descriptor characters (hex, keypaths) are in the first group of 32. * - Case errors cause an offset that's a multiple of 32. * - As many alphabetic characters are in the same group (while following the above restrictions). * * If p(x) gives the position of a character c in this character set, every group of 3 characters * (a,b,c) is encoded as the 4 symbols (p(a) & 31, p(b) & 31, p(c) & 31, (p(a) / 32) + 3 * (p(b) / 32) + 9 * (p(c) / 32). * This means that changes that only affect the lower 5 bits of the position, or only the higher 2 bits, will just * affect a single symbol. * * As a result, within-group-of-32 errors count as 1 symbol, as do cross-group errors that don't affect * the position within the groups. */ static std::string INPUT_CHARSET = "0123456789()[],'/*abcdefgh@:$%{}" "IJKLMNOPQRSTUVWXYZ&+-.;<=>?!^_|~" "ijklmnopqrstuvwxyzABCDEFGH`#\"\\ "; /** The character set for the checksum itself (same as bech32). */ static std::string CHECKSUM_CHARSET = "qpzry9x8gf2tvdw0s3jn54khce6mua7l"; uint64_t c = 1; int cls = 0; int clscount = 0; for (auto ch : span) { auto pos = INPUT_CHARSET.find(ch); if (pos == std::string::npos) return ""; c = PolyMod(c, pos & 31); // Emit a symbol for the position inside the group, for every character. cls = cls * 3 + (pos >> 5); // Accumulate the group numbers if (++clscount == 3) { // Emit an extra symbol representing the group numbers, for every 3 characters. c = PolyMod(c, cls); cls = 0; clscount = 0; } } if (clscount > 0) c = PolyMod(c, cls); for (int j = 0; j < 8; ++j) c = PolyMod(c, 0); // Shift further to determine the checksum. c ^= 1; // Prevent appending zeroes from not affecting the checksum. std::string ret(8, ' '); for (int j = 0; j < 8; ++j) ret[j] = CHECKSUM_CHARSET[(c >> (5 * (7 - j))) & 31]; return ret;}std::string AddChecksum(const std::string& str) { return str + "#" + DescriptorChecksum(str); }////////////////////////////////////////////////////////////////////////////// Internal representation //////////////////////////////////////////////////////////////////////////////typedef std::vector<uint32_t> KeyPath;/** Interface for public key objects in descriptors. */struct PubkeyProvider{protected: //! Index of this key expression in the descriptor //! E.g. If this PubkeyProvider is key1 in multi(2, key1, key2, key3), then m_expr_index = 0 uint32_t m_expr_index;public: PubkeyProvider(uint32_t exp_index) : m_expr_index(exp_index) {} virtual ~PubkeyProvider() = default; /** Derive a public key. * read_cache is the cache to read keys from (if not nullptr) * write_cache is the cache to write keys to (if not nullptr) * Caches are not exclusive but this is not tested. Currently we use them exclusively */ virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) = 0; /** Whether this represent multiple public keys at different positions. */ virtual bool IsRange() const = 0; /** Get the size of the generated public key(s) in bytes (33 or 65). */ virtual size_t GetSize() const = 0; /** Get the descriptor string form. */ virtual std::string ToString() const = 0; /** Get the descriptor string form including private data (if available in arg). */ virtual bool ToPrivateString(const SigningProvider& arg, std::string& out) const = 0; /** Derive a private key, if private data is available in arg. */ virtual bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const = 0;};class OriginPubkeyProvider final : public PubkeyProvider{ KeyOriginInfo m_origin; std::unique_ptr<PubkeyProvider> m_provider; std::string OriginString() const { return HexStr(m_origin.fingerprint) + FormatHDKeypath(m_origin.path); }public: OriginPubkeyProvider(uint32_t exp_index, KeyOriginInfo info, std::unique_ptr<PubkeyProvider> provider) : PubkeyProvider(exp_index), m_origin(std::move(info)), m_provider(std::move(provider)) {} bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) override { if (!m_provider->GetPubKey(pos, arg, key, info, read_cache, write_cache)) return false; std::copy(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint), info.fingerprint); info.path.insert(info.path.begin(), m_origin.path.begin(), m_origin.path.end()); return true; } bool IsRange() const override { return m_provider->IsRange(); } size_t GetSize() const override { return m_provider->GetSize(); } std::string ToString() const override { return "[" + OriginString() + "]" + m_provider->ToString(); } bool ToPrivateString(const SigningProvider& arg, std::string& ret) const override { std::string sub; if (!m_provider->ToPrivateString(arg, sub)) return false; ret = "[" + OriginString() + "]" + std::move(sub); return true; } bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override { return m_provider->GetPrivKey(pos, arg, key); }};/** An object representing a parsed constant public key in a descriptor. */class ConstPubkeyProvider final : public PubkeyProvider{ CPubKey m_pubkey;public: ConstPubkeyProvider(uint32_t exp_index, const CPubKey& pubkey) : PubkeyProvider(exp_index), m_pubkey(pubkey) {} bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) override { key = m_pubkey; info.path.clear(); CKeyID keyid = m_pubkey.GetID(); std::copy(keyid.begin(), keyid.begin() + sizeof(info.fingerprint), info.fingerprint); return true; } bool IsRange() const override { return false; } size_t GetSize() const override { return m_pubkey.size(); } std::string ToString() const override { return HexStr(m_pubkey); } bool ToPrivateString(const SigningProvider& arg, std::string& ret) const override { CKey key; if (!arg.GetKey(m_pubkey.GetID(), key)) return false; ret = EncodeSecret(key); return true; } bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override { return arg.GetKey(m_pubkey.GetID(), key); }};enum class DeriveType { NO, UNHARDENED, HARDENED,};/** An object representing a parsed extended public key in a descriptor. */class BIP32PubkeyProvider final : public PubkeyProvider{ // Root xpub, path, and final derivation step type being used, if any CExtPubKey m_root_extkey; KeyPath m_path; DeriveType m_derive; // Cache of the parent of the final derived pubkeys. // Primarily useful for situations when no read_cache is provided CExtPubKey m_cached_xpub; bool GetExtKey(const SigningProvider& arg, CExtKey& ret) const { CKey key; if (!arg.GetKey(m_root_extkey.pubkey.GetID(), key)) return false; ret.nDepth = m_root_extkey.nDepth; std::copy(m_root_extkey.vchFingerprint, m_root_extkey.vchFingerprint + sizeof(ret.vchFingerprint), ret.vchFingerprint); ret.nChild = m_root_extkey.nChild; ret.chaincode = m_root_extkey.chaincode; ret.key = key; return true; } // Derives the last xprv bool GetDerivedExtKey(const SigningProvider& arg, CExtKey& xprv) const { if (!GetExtKey(arg, xprv)) return false; for (auto entry : m_path) { xprv.Derive(xprv, entry); } return true; } bool IsHardened() const { if (m_derive == DeriveType::HARDENED) return true; for (auto entry : m_path) { if (entry >> 31) return true; } return false; }public: BIP32PubkeyProvider(uint32_t exp_index, const CExtPubKey& extkey, KeyPath path, DeriveType derive) : PubkeyProvider(exp_index), m_root_extkey(extkey), m_path(std::move(path)), m_derive(derive) {} bool IsRange() const override { return m_derive != DeriveType::NO; } size_t GetSize() const override { return 33; } bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key_out, KeyOriginInfo& final_info_out, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) override { // Info of parent of the to be derived pubkey KeyOriginInfo parent_info; CKeyID keyid = m_root_extkey.pubkey.GetID(); std::copy(keyid.begin(), keyid.begin() + sizeof(parent_info.fingerprint), parent_info.fingerprint); parent_info.path = m_path; // Info of the derived key itself which is copied out upon successful completion KeyOriginInfo final_info_out_tmp = parent_info; if (m_derive == DeriveType::UNHARDENED) final_info_out_tmp.path.push_back((uint32_t)pos); if (m_derive == DeriveType::HARDENED) final_info_out_tmp.path.push_back(((uint32_t)pos) | 0x80000000L); // Derive keys or fetch them from cache CExtPubKey final_extkey = m_root_extkey; CExtPubKey parent_extkey = m_root_extkey; bool der = true; if (read_cache) { if (!read_cache->GetCachedDerivedExtPubKey(m_expr_index, pos, final_extkey)) { if (m_derive == DeriveType::HARDENED) return false; // Try to get the derivation parent if (!read_cache->GetCachedParentExtPubKey(m_expr_index, parent_extkey)) return false; final_extkey = parent_extkey; if (m_derive == DeriveType::UNHARDENED) der = parent_extkey.Derive(final_extkey, pos); } } else if (m_cached_xpub.pubkey.IsValid() && m_derive != DeriveType::HARDENED) { parent_extkey = final_extkey = m_cached_xpub; if (m_derive == DeriveType::UNHARDENED) der = parent_extkey.Derive(final_extkey, pos); } else if (IsHardened()) { CExtKey xprv; if (!GetDerivedExtKey(arg, xprv)) return false; parent_extkey = xprv.Neuter(); if (m_derive == DeriveType::UNHARDENED) der = xprv.Derive(xprv, pos); if (m_derive == DeriveType::HARDENED) der = xprv.Derive(xprv, pos | 0x80000000UL); final_extkey = xprv.Neuter(); } else { for (auto entry : m_path) { der = parent_extkey.Derive(parent_extkey, entry); assert(der); } final_extkey = parent_extkey; if (m_derive == DeriveType::UNHARDENED) der = parent_extkey.Derive(final_extkey, pos); assert(m_derive != DeriveType::HARDENED); } assert(der); final_info_out = final_info_out_tmp; key_out = final_extkey.pubkey; // We rely on the consumer to check that m_derive isn't HARDENED as above // But we can't have already cached something in case we read something from the cache // and parent_extkey isn't actually the parent. if (!m_cached_xpub.pubkey.IsValid()) m_cached_xpub = parent_extkey; if (write_cache) { // Only cache parent if there is any unhardened derivation if (m_derive != DeriveType::HARDENED) { write_cache->CacheParentExtPubKey(m_expr_index, parent_extkey); } else if (final_info_out.path.size() > 0) { write_cache->CacheDerivedExtPubKey(m_expr_index, pos, final_extkey); } } return true; } std::string ToString() const override { std::string ret = EncodeExtPubKey(m_root_extkey) + FormatHDKeypath(m_path); if (IsRange()) { ret += "/*"; if (m_derive == DeriveType::HARDENED) ret += '\''; } return ret; } bool ToPrivateString(const SigningProvider& arg, std::string& out) const override { CExtKey key; if (!GetExtKey(arg, key)) return false; out = EncodeExtKey(key) + FormatHDKeypath(m_path); if (IsRange()) { out += "/*"; if (m_derive == DeriveType::HARDENED) out += '\''; } return true; } bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override { CExtKey extkey; if (!GetDerivedExtKey(arg, extkey)) return false; if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos); if (m_derive == DeriveType::HARDENED) extkey.Derive(extkey, pos | 0x80000000UL); key = extkey.key; return true; }};/** Base class for all Descriptor implementations. */class DescriptorImpl : public Descriptor{ //! Public key arguments for this descriptor (size 1 for PK, PKH, WPKH; any size for Multisig). const std::vector<std::unique_ptr<PubkeyProvider>> m_pubkey_args; //! The string name of the descriptor function. const std::string m_name;protected: //! The sub-descriptor argument (nullptr for everything but SH and WSH). //! In doc/descriptors.m this is referred to as SCRIPT expressions sh(SCRIPT) //! and wsh(SCRIPT), and distinct from KEY expressions and ADDR expressions. const std::unique_ptr<DescriptorImpl> m_subdescriptor_arg; //! Return a serialization of anything except pubkey and script arguments, to be prepended to those. virtual std::string ToStringExtra() const { return ""; } /** A helper function to construct the scripts for this descriptor. * * This function is invoked once for every CScript produced by evaluating * m_subdescriptor_arg, or just once in case m_subdescriptor_arg is nullptr. * @param pubkeys The evaluations of the m_pubkey_args field. * @param script The evaluation of m_subdescriptor_arg (or nullptr when m_subdescriptor_arg is nullptr). * @param out A FlatSigningProvider to put scripts or public keys in that are necessary to the solver. * The script arguments to this function are automatically added, as is the origin info of the provided pubkeys. * @return A vector with scriptPubKeys for this descriptor. */ virtual std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>& pubkeys, const CScript* script, FlatSigningProvider& out) const = 0;public: DescriptorImpl(std::vector<std::unique_ptr<PubkeyProvider>> pubkeys, std::unique_ptr<DescriptorImpl> script, const std::string& name) : m_pubkey_args(std::move(pubkeys)), m_name(name), m_subdescriptor_arg(std::move(script)) {} bool IsSolvable() const override { if (m_subdescriptor_arg) { if (!m_subdescriptor_arg->IsSolvable()) return false; } return true; } bool IsRange() const final { for (const auto& pubkey : m_pubkey_args) { if (pubkey->IsRange()) return true; } if (m_subdescriptor_arg) { if (m_subdescriptor_arg->IsRange()) return true; } return false; } bool ToStringHelper(const SigningProvider* arg, std::string& out, bool priv) const { std::string extra = ToStringExtra(); size_t pos = extra.size() > 0 ? 1 : 0; std::string ret = m_name + "(" + extra; for (const auto& pubkey : m_pubkey_args) { if (pos++) ret += ","; std::string tmp; if (priv) { if (!pubkey->ToPrivateString(*arg, tmp)) return false; } else { tmp = pubkey->ToString(); } ret += std::move(tmp); } if (m_subdescriptor_arg) { if (pos++) ret += ","; std::string tmp; if (!m_subdescriptor_arg->ToStringHelper(arg, tmp, priv)) return false; ret += std::move(tmp); } out = std::move(ret) + ")"; return true; } std::string ToString() const final { std::string ret; ToStringHelper(nullptr, ret, false); return AddChecksum(ret); } bool ToPrivateString(const SigningProvider& arg, std::string& out) const final { bool ret = ToStringHelper(&arg, out, true); out = AddChecksum(out); return ret; } bool ExpandHelper(int pos, const SigningProvider& arg, const DescriptorCache* read_cache, std::vector<DestinationAddr>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache) const { std::vector<std::pair<CPubKey, KeyOriginInfo>> entries; entries.reserve(m_pubkey_args.size()); // Construct temporary data in `entries` and `subscripts`, to avoid producing output in case of failure. for (const auto& p : m_pubkey_args) { entries.emplace_back(); if (!p->GetPubKey(pos, arg, entries.back().first, entries.back().second, read_cache, write_cache)) return false; } std::vector<DestinationAddr> subscripts; if (m_subdescriptor_arg) { FlatSigningProvider subprovider; if (!m_subdescriptor_arg->ExpandHelper(pos, arg, read_cache, subscripts, subprovider, write_cache)) return false; out = Merge(out, subprovider); } std::vector<CPubKey> pubkeys; pubkeys.reserve(entries.size()); for (auto& entry : entries) { pubkeys.push_back(entry.first); out.origins.emplace(entry.first.GetID(), std::make_pair<CPubKey, KeyOriginInfo>(CPubKey(entry.first), std::move(entry.second))); } if (m_subdescriptor_arg) { for (const auto& subscript : subscripts) { out.scripts.emplace(CScriptID(subscript.GetScript()), subscript.GetScript()); std::vector<DestinationAddr> addscripts = MakeScripts(pubkeys, &subscript.GetScript(), out); for (auto& addscript : addscripts) { output_scripts.push_back(std::move(addscript)); } } } else { output_scripts = MakeScripts(pubkeys, nullptr, out); } return true; } bool Expand(int pos, const SigningProvider& provider, std::vector<DestinationAddr>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache = nullptr) const final { return ExpandHelper(pos, provider, nullptr, output_scripts, out, write_cache); } bool ExpandFromCache(int pos, const DescriptorCache& read_cache, std::vector<DestinationAddr>& output_scripts, FlatSigningProvider& out) const final { return ExpandHelper(pos, DUMMY_SIGNING_PROVIDER, &read_cache, output_scripts, out, nullptr); } void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const final { for (const auto& p : m_pubkey_args) { CKey key; if (!p->GetPrivKey(pos, provider, key)) continue; out.keys.emplace(key.GetPubKey().GetID(), key); } if (m_subdescriptor_arg) { FlatSigningProvider subprovider; m_subdescriptor_arg->ExpandPrivate(pos, provider, subprovider); out = Merge(out, subprovider); } } Optional<OutputType> GetOutputType() const override { return nullopt; }};/** A parsed addr(A) descriptor. */class AddressDescriptor final : public DescriptorImpl{ const CTxDestination m_destination;protected: std::string ToStringExtra() const override { return EncodeDestination(m_destination); } std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Vector(DestinationAddr(m_destination)); }public: AddressDescriptor(CTxDestination destination) : DescriptorImpl({}, {}, "addr"), m_destination(std::move(destination)) {} bool IsSolvable() const final { return false; } Optional<OutputType> GetOutputType() const override { switch (m_destination.which()) { case 1 /* PKHash */: case 2 /* ScriptHash */: return OutputType::LEGACY; case 3 /* WitnessV0ScriptHash */: case 4 /* WitnessV0KeyHash */: case 5 /* WitnessUnknown */: return OutputType::BECH32; case 6 /* StealthAddress */: return OutputType::MWEB; case 0 /* CNoDestination */: default: return nullopt; } } bool IsSingleType() const final { return true; }};/** A parsed raw(H) descriptor. */class RawDescriptor final : public DescriptorImpl{ const CScript m_script;protected: std::string ToStringExtra() const override { return HexStr(m_script); } std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Vector(DestinationAddr{m_script}); }public: RawDescriptor(CScript script) : DescriptorImpl({}, {}, "raw"), m_script(std::move(script)) {} bool IsSolvable() const final { return false; } Optional<OutputType> GetOutputType() const override { CTxDestination dest; ExtractDestination(m_script, dest); switch (dest.which()) { case 1 /* PKHash */: case 2 /* ScriptHash */: return OutputType::LEGACY; case 3 /* WitnessV0ScriptHash */: case 4 /* WitnessV0KeyHash */: case 5 /* WitnessUnknown */: return OutputType::BECH32; case 6 /* StealthAddress */: return OutputType::MWEB; case 0 /* CNoDestination */: default: return nullopt; } } bool IsSingleType() const final { return true; }};/** A parsed pk(P) descriptor. */class PKDescriptor final : public DescriptorImpl{protected: std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { return Vector(DestinationAddr(GetScriptForRawPubKey(keys[0]))); }public: PKDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "pk") {} bool IsSingleType() const final { return true; }};/** A parsed pkh(P) descriptor. */class PKHDescriptor final : public DescriptorImpl{protected: std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override { CKeyID id = keys[0].GetID(); out.pubkeys.emplace(id, keys[0]); return Vector(DestinationAddr(PKHash(id))); }public: PKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "pkh") {} Optional<OutputType> GetOutputType() const override { return OutputType::LEGACY; } bool IsSingleType() const final { return true; }};/** A parsed wpkh(P) descriptor. */class WPKHDescriptor final : public DescriptorImpl{protected: std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override { CKeyID id = keys[0].GetID(); out.pubkeys.emplace(id, keys[0]); return Vector(DestinationAddr(WitnessV0KeyHash(id))); }public: WPKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "wpkh") {} Optional<OutputType> GetOutputType() const override { return OutputType::BECH32; } bool IsSingleType() const final { return true; }};/** A parsed mweb descriptor. */class MWEBDescriptor final : public DescriptorImpl{ SecretKey m_scanSecret;protected: std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override { PublicKey B(keys[0].data()); PublicKey A = B.Mul(m_scanSecret); return Vector(DestinationAddr(StealthAddress(A, B))); }public: MWEBDescriptor(std::unique_ptr<PubkeyProvider> prov, SecretKey scan_secret) : DescriptorImpl(Vector(std::move(prov)), {}, "mweb"), m_scanSecret(std::move(scan_secret)) {} Optional<OutputType> GetOutputType() const final { return OutputType::MWEB; } bool IsSingleType() const final { return true; }};/** A parsed combo(P) descriptor. */class ComboDescriptor final : public DescriptorImpl{protected: std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override { std::vector<DestinationAddr> ret; CKeyID id = keys[0].GetID(); out.pubkeys.emplace(id, keys[0]); ret.emplace_back(GetScriptForRawPubKey(keys[0])); // P2PK ret.emplace_back(GetScriptForDestination(PKHash(id))); // P2PKH if (keys[0].IsCompressed()) { CScript p2wpkh = GetScriptForDestination(WitnessV0KeyHash(id)); out.scripts.emplace(CScriptID(p2wpkh), p2wpkh); ret.emplace_back(p2wpkh); ret.emplace_back(GetScriptForDestination(ScriptHash(p2wpkh))); // P2SH-P2WPKH } return ret; }public: ComboDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "combo") {} bool IsSingleType() const final { return false; }};/** A parsed multi(...) or sortedmulti(...) descriptor */class MultisigDescriptor final : public DescriptorImpl{ const int m_threshold; const bool m_sorted;protected: std::string ToStringExtra() const override { return strprintf("%i", m_threshold); } std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { if (m_sorted) { std::vector<CPubKey> sorted_keys(keys); std::sort(sorted_keys.begin(), sorted_keys.end()); return Vector(DestinationAddr(GetScriptForMultisig(m_threshold, sorted_keys))); } return Vector(DestinationAddr(GetScriptForMultisig(m_threshold, keys))); }public: MultisigDescriptor(int threshold, std::vector<std::unique_ptr<PubkeyProvider>> providers, bool sorted = false) : DescriptorImpl(std::move(providers), {}, sorted ? "sortedmulti" : "multi"), m_threshold(threshold), m_sorted(sorted) {} bool IsSingleType() const final { return true; }};/** A parsed sh(...) descriptor. */class SHDescriptor final : public DescriptorImpl{protected: std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Vector(DestinationAddr(ScriptHash(*script))); }public: SHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "sh") {} Optional<OutputType> GetOutputType() const override { assert(m_subdescriptor_arg); if (m_subdescriptor_arg->GetOutputType() == OutputType::BECH32) return OutputType::P2SH_SEGWIT; return OutputType::LEGACY; } bool IsSingleType() const final { return true; }};/** A parsed wsh(...) descriptor. */class WSHDescriptor final : public DescriptorImpl{protected: std::vector<DestinationAddr> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Vector(DestinationAddr(WitnessV0ScriptHash(*script))); }public: WSHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "wsh") {} Optional<OutputType> GetOutputType() const override { return OutputType::BECH32; } bool IsSingleType() const final { return true; }};////////////////////////////////////////////////////////////////////////////// Parser //////////////////////////////////////////////////////////////////////////////enum class ParseScriptContext { TOP, P2SH, P2WSH,};/** Parse a key path, being passed a split list of elements (the first element is ignored). */NODISCARD bool ParseKeyPath(const std::vector<Span<const char>>& split, KeyPath& out, std::string& error){ for (size_t i = 1; i < split.size(); ++i) { Span<const char> elem = split[i]; bool hardened = false; if (elem.size() > 0 && (elem[elem.size() - 1] == '\'' || elem[elem.size() - 1] == 'h')) { elem = elem.first(elem.size() - 1); hardened = true; } uint32_t p; if (!ParseUInt32(std::string(elem.begin(), elem.end()), &p)) { error = strprintf("Key path value '%s' is not a valid uint32", std::string(elem.begin(), elem.end())); return false; } else if (p > 0x7FFFFFFFUL) { error = strprintf("Key path value %u is out of range", p); return false; } out.push_back(p | (((uint32_t)hardened) << 31)); } return true;}/** Parse a public key that excludes origin information. */std::unique_ptr<PubkeyProvider> ParsePubkeyInner(uint32_t key_exp_index, const Span<const char>& sp, bool permit_uncompressed, FlatSigningProvider& out, std::string& error){ using namespace spanparsing; auto split = Split(sp, '/'); std::string str(split[0].begin(), split[0].end()); if (str.size() == 0) { error = "No key provided"; return nullptr; } if (split.size() == 1) { if (IsHex(str)) { std::vector<unsigned char> data = ParseHex(str); CPubKey pubkey(data); if (pubkey.IsFullyValid()) { if (permit_uncompressed || pubkey.IsCompressed()) { return MakeUnique<ConstPubkeyProvider>(key_exp_index, pubkey); } else { error = "Uncompressed keys are not allowed"; return nullptr; } } error = strprintf("Pubkey '%s' is invalid", str); return nullptr; } CKey key = DecodeSecret(str); if (key.IsValid()) { if (permit_uncompressed || key.IsCompressed()) { CPubKey pubkey = key.GetPubKey(); out.keys.emplace(pubkey.GetID(), key); return MakeUnique<ConstPubkeyProvider>(key_exp_index, pubkey); } else { error = "Uncompressed keys are not allowed"; return nullptr; } } } CExtKey extkey = DecodeExtKey(str); CExtPubKey extpubkey = DecodeExtPubKey(str); if (!extkey.key.IsValid() && !extpubkey.pubkey.IsValid()) { error = strprintf("key '%s' is not valid", str); return nullptr; } KeyPath path; DeriveType type = DeriveType::NO; if (split.back() == MakeSpan("*").first(1)) { split.pop_back(); type = DeriveType::UNHARDENED; } else if (split.back() == MakeSpan("*'").first(2) || split.back() == MakeSpan("*h").first(2)) { split.pop_back(); type = DeriveType::HARDENED; } if (!ParseKeyPath(split, path, error)) return nullptr; if (extkey.key.IsValid()) { extpubkey = extkey.Neuter(); out.keys.emplace(extpubkey.pubkey.GetID(), extkey.key); } return MakeUnique<BIP32PubkeyProvider>(key_exp_index, extpubkey, std::move(path), type);}/** Parse a public key including origin information (if enabled). */std::unique_ptr<PubkeyProvider> ParsePubkey(uint32_t key_exp_index, const Span<const char>& sp, bool permit_uncompressed, FlatSigningProvider& out, std::string& error){ using namespace spanparsing; auto origin_split = Split(sp, ']'); if (origin_split.size() > 2) { error = "Multiple ']' characters found for a single pubkey"; return nullptr; } if (origin_split.size() == 1) return ParsePubkeyInner(key_exp_index, origin_split[0], permit_uncompressed, out, error); if (origin_split[0].empty() || origin_split[0][0] != '[') { error = strprintf("Key origin start '[ character expected but not found, got '%c' instead", origin_split[0].empty() ? /** empty, implies split char */ ']' : origin_split[0][0]); return nullptr; } auto slash_split = Split(origin_split[0].subspan(1), '/'); if (slash_split[0].size() != 8) { error = strprintf("Fingerprint is not 4 bytes (%u characters instead of 8 characters)", slash_split[0].size()); return nullptr; } std::string fpr_hex = std::string(slash_split[0].begin(), slash_split[0].end()); if (!IsHex(fpr_hex)) { error = strprintf("Fingerprint '%s' is not hex", fpr_hex); return nullptr; } auto fpr_bytes = ParseHex(fpr_hex); KeyOriginInfo info; static_assert(sizeof(info.fingerprint) == 4, "Fingerprint must be 4 bytes"); assert(fpr_bytes.size() == 4); std::copy(fpr_bytes.begin(), fpr_bytes.end(), info.fingerprint); if (!ParseKeyPath(slash_split, info.path, error)) return nullptr; auto provider = ParsePubkeyInner(key_exp_index, origin_split[1], permit_uncompressed, out, error); if (!provider) return nullptr; return MakeUnique<OriginPubkeyProvider>(key_exp_index, std::move(info), std::move(provider));}/** Parse a script in a particular context. */std::unique_ptr<DescriptorImpl> ParseScript(uint32_t key_exp_index, Span<const char>& sp, ParseScriptContext ctx, FlatSigningProvider& out, std::string& error){ using namespace spanparsing; auto expr = Expr(sp); bool sorted_multi = false; if (Func("pk", expr)) { auto pubkey = ParsePubkey(key_exp_index, expr, ctx != ParseScriptContext::P2WSH, out, error); if (!pubkey) return nullptr; return MakeUnique<PKDescriptor>(std::move(pubkey)); } if (Func("pkh", expr)) { auto pubkey = ParsePubkey(key_exp_index, expr, ctx != ParseScriptContext::P2WSH, out, error); if (!pubkey) return nullptr; return MakeUnique<PKHDescriptor>(std::move(pubkey)); } if (Func("mweb", expr)) { auto pubkey = ParsePubkey(key_exp_index, expr, false, out, error); if (!pubkey) return nullptr; return MakeUnique<MWEBDescriptor>(std::move(pubkey), SecretKey::Null()); } if (ctx == ParseScriptContext::TOP && Func("combo", expr)) { auto pubkey = ParsePubkey(key_exp_index, expr, true, out, error); if (!pubkey) return nullptr; return MakeUnique<ComboDescriptor>(std::move(pubkey)); } else if (ctx != ParseScriptContext::TOP && Func("combo", expr)) { error = "Cannot have combo in non-top level"; return nullptr; } if ((sorted_multi = Func("sortedmulti", expr)) || Func("multi", expr)) { auto threshold = Expr(expr); uint32_t thres; std::vector<std::unique_ptr<PubkeyProvider>> providers; if (!ParseUInt32(std::string(threshold.begin(), threshold.end()), &thres)) { error = strprintf("Multi threshold '%s' is not valid", std::string(threshold.begin(), threshold.end())); return nullptr; } size_t script_size = 0; while (expr.size()) { if (!Const(",", expr)) { error = strprintf("Multi: expected ',', got '%c'", expr[0]); return nullptr; } auto arg = Expr(expr); auto pk = ParsePubkey(key_exp_index, arg, ctx != ParseScriptContext::P2WSH, out, error); if (!pk) return nullptr; script_size += pk->GetSize() + 1; providers.emplace_back(std::move(pk)); key_exp_index++; } if (providers.empty() || providers.size() > 16) { error = strprintf("Cannot have %u keys in multisig; must have between 1 and 16 keys, inclusive", providers.size()); return nullptr; } else if (thres < 1) { error = strprintf("Multisig threshold cannot be %d, must be at least 1", thres); return nullptr; } else if (thres > providers.size()) { error = strprintf("Multisig threshold cannot be larger than the number of keys; threshold is %d but only %u keys specified", thres, providers.size()); return nullptr; } if (ctx == ParseScriptContext::TOP) { if (providers.size() > 3) { error = strprintf("Cannot have %u pubkeys in bare multisig; only at most 3 pubkeys", providers.size()); return nullptr; } } if (ctx == ParseScriptContext::P2SH) { if (script_size + 3 > MAX_SCRIPT_ELEMENT_SIZE) { error = strprintf("P2SH script is too large, %d bytes is larger than %d bytes", script_size + 3, MAX_SCRIPT_ELEMENT_SIZE); return nullptr; } } return MakeUnique<MultisigDescriptor>(thres, std::move(providers), sorted_multi); } if (ctx != ParseScriptContext::P2WSH && Func("wpkh", expr)) { auto pubkey = ParsePubkey(key_exp_index, expr, false, out, error); if (!pubkey) return nullptr; return MakeUnique<WPKHDescriptor>(std::move(pubkey)); } else if (ctx == ParseScriptContext::P2WSH && Func("wpkh", expr)) { error = "Cannot have wpkh within wsh"; return nullptr; } if (ctx == ParseScriptContext::TOP && Func("sh", expr)) { auto desc = ParseScript(key_exp_index, expr, ParseScriptContext::P2SH, out, error); if (!desc || expr.size()) return nullptr; return MakeUnique<SHDescriptor>(std::move(desc)); } else if (ctx != ParseScriptContext::TOP && Func("sh", expr)) { error = "Cannot have sh in non-top level"; return nullptr; } if (ctx != ParseScriptContext::P2WSH && Func("wsh", expr)) { auto desc = ParseScript(key_exp_index, expr, ParseScriptContext::P2WSH, out, error); if (!desc || expr.size()) return nullptr; return MakeUnique<WSHDescriptor>(std::move(desc)); } else if (ctx == ParseScriptContext::P2WSH && Func("wsh", expr)) { error = "Cannot have wsh within wsh"; return nullptr; } if (ctx == ParseScriptContext::TOP && Func("addr", expr)) { CTxDestination dest = DecodeDestination(std::string(expr.begin(), expr.end())); if (!IsValidDestination(dest)) { error = "Address is not valid"; return nullptr; } return MakeUnique<AddressDescriptor>(std::move(dest)); } if (ctx == ParseScriptContext::TOP && Func("raw", expr)) { std::string str(expr.begin(), expr.end()); if (!IsHex(str)) { error = "Raw script is not hex"; return nullptr; } auto bytes = ParseHex(str); return MakeUnique<RawDescriptor>(CScript(bytes.begin(), bytes.end())); } if (ctx == ParseScriptContext::P2SH) { error = "A function is needed within P2SH"; return nullptr; } else if (ctx == ParseScriptContext::P2WSH) { error = "A function is needed within P2WSH"; return nullptr; } error = strprintf("%s is not a valid descriptor function", std::string(expr.begin(), expr.end())); return nullptr;}std::unique_ptr<PubkeyProvider> InferPubkey(const CPubKey& pubkey, ParseScriptContext, const SigningProvider& provider){ std::unique_ptr<PubkeyProvider> key_provider = MakeUnique<ConstPubkeyProvider>(0, pubkey); KeyOriginInfo info; if (provider.GetKeyOrigin(pubkey.GetID(), info)) { return MakeUnique<OriginPubkeyProvider>(0, std::move(info), std::move(key_provider)); } return key_provider;}std::unique_ptr<DescriptorImpl> InferScript(const CScript& script, ParseScriptContext ctx, const SigningProvider& provider){ std::vector<std::vector<unsigned char>> data; TxoutType txntype = Solver(script, data); if (txntype == TxoutType::PUBKEY) { CPubKey pubkey(data[0].begin(), data[0].end()); if (pubkey.IsValid()) { return MakeUnique<PKDescriptor>(InferPubkey(pubkey, ctx, provider)); } } if (txntype == TxoutType::PUBKEYHASH) { uint160 hash(data[0]); CKeyID keyid(hash); CPubKey pubkey; if (provider.GetPubKey(keyid, pubkey)) { return MakeUnique<PKHDescriptor>(InferPubkey(pubkey, ctx, provider)); } } if (txntype == TxoutType::WITNESS_V0_KEYHASH && ctx != ParseScriptContext::P2WSH) { uint160 hash(data[0]); CKeyID keyid(hash); CPubKey pubkey; if (provider.GetPubKey(keyid, pubkey)) { return MakeUnique<WPKHDescriptor>(InferPubkey(pubkey, ctx, provider)); } } if (txntype == TxoutType::MULTISIG) { std::vector<std::unique_ptr<PubkeyProvider>> providers; for (size_t i = 1; i + 1 < data.size(); ++i) { CPubKey pubkey(data[i].begin(), data[i].end()); providers.push_back(InferPubkey(pubkey, ctx, provider)); } return MakeUnique<MultisigDescriptor>((int)data[0][0], std::move(providers)); } if (txntype == TxoutType::SCRIPTHASH && ctx == ParseScriptContext::TOP) { uint160 hash(data[0]); CScriptID scriptid(hash); CScript subscript; if (provider.GetCScript(scriptid, subscript)) { auto sub = InferScript(subscript, ParseScriptContext::P2SH, provider); if (sub) return MakeUnique<SHDescriptor>(std::move(sub)); } } if (txntype == TxoutType::WITNESS_V0_SCRIPTHASH && ctx != ParseScriptContext::P2WSH) { CScriptID scriptid; CRIPEMD160().Write(data[0].data(), data[0].size()).Finalize(scriptid.begin()); CScript subscript; if (provider.GetCScript(scriptid, subscript)) { auto sub = InferScript(subscript, ParseScriptContext::P2WSH, provider); if (sub) return MakeUnique<WSHDescriptor>(std::move(sub)); } } CTxDestination dest; if (ExtractDestination(script, dest)) { if (GetScriptForDestination(dest) == script) { return MakeUnique<AddressDescriptor>(std::move(dest)); } } return MakeUnique<RawDescriptor>(script);}} // namespace/** Check a descriptor checksum, and update desc to be the checksum-less part. */bool CheckChecksum(Span<const char>& sp, bool require_checksum, std::string& error, std::string* out_checksum = nullptr){ using namespace spanparsing; auto check_split = Split(sp, '#'); if (check_split.size() > 2) { error = "Multiple '#' symbols"; return false; } if (check_split.size() == 1 && require_checksum){ error = "Missing checksum"; return false; } if (check_split.size() == 2) { if (check_split[1].size() != 8) { error = strprintf("Expected 8 character checksum, not %u characters", check_split[1].size()); return false; } } auto checksum = DescriptorChecksum(check_split[0]); if (checksum.empty()) { error = "Invalid characters in payload"; return false; } if (check_split.size() == 2) { if (!std::equal(checksum.begin(), checksum.end(), check_split[1].begin())) { error = strprintf("Provided checksum '%s' does not match computed checksum '%s'", std::string(check_split[1].begin(), check_split[1].end()), checksum); return false; } } if (out_checksum) *out_checksum = std::move(checksum); sp = check_split[0]; return true;}std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out, std::string& error, bool require_checksum){ Span<const char> sp{descriptor}; if (!CheckChecksum(sp, require_checksum, error)) return nullptr; auto ret = ParseScript(0, sp, ParseScriptContext::TOP, out, error); if (sp.size() == 0 && ret) return std::unique_ptr<Descriptor>(std::move(ret)); return nullptr;}std::string GetDescriptorChecksum(const std::string& descriptor){ std::string ret; std::string error; Span<const char> sp{descriptor}; if (!CheckChecksum(sp, false, error, &ret)) return ""; return ret;}std::unique_ptr<Descriptor> InferDescriptor(const DestinationAddr& script, const SigningProvider& provider){ if (script.IsMWEB()) { CPubKey pubkey(script.GetMWEBAddress().GetSpendPubKey().vec()); return MakeUnique<MWEBDescriptor>(InferPubkey(pubkey, ParseScriptContext::TOP, provider), SecretKey::Null()); } return InferScript(script.GetScript(), ParseScriptContext::TOP, provider);}void DescriptorCache::CacheParentExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub){ m_parent_xpubs[key_exp_pos] = xpub;}void DescriptorCache::CacheDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, const CExtPubKey& xpub){ auto& xpubs = m_derived_xpubs[key_exp_pos]; xpubs[der_index] = xpub;}bool DescriptorCache::GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const{ const auto& it = m_parent_xpubs.find(key_exp_pos); if (it == m_parent_xpubs.end()) return false; xpub = it->second; return true;}bool DescriptorCache::GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const{ const auto& key_exp_it = m_derived_xpubs.find(key_exp_pos); if (key_exp_it == m_derived_xpubs.end()) return false; const auto& der_it = key_exp_it->second.find(der_index); if (der_it == key_exp_it->second.end()) return false; xpub = der_it->second; return true;}const ExtPubKeyMap DescriptorCache::GetCachedParentExtPubKeys() const{ return m_parent_xpubs;}const std::unordered_map<uint32_t, ExtPubKeyMap> DescriptorCache::GetCachedDerivedExtPubKeys() const{ return m_derived_xpubs;}