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bitcoin/src/script/descriptor.cpp
Pieter Wuille e65e61c812 Add some general std::vector utility functions 
Added are:

* Vector(arg1,arg2,arg3,...) constructs a vector with the specified
  arguments as elements. The vector's type is derived from the
  arguments. If some of the arguments are rvalue references, they
  will be moved into place rather than copied (which can't be achieved
  using list initialization).

* Cat(vector1,vector2) returns a concatenation of the two vectors,
  efficiently moving elements when relevant.

Vector generalizes (and replaces) the Singleton function in
src/descriptor.cpp, and Cat replaces the Cat function in bech32.cpp
2019-10-16 08:56:57 -07:00

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// Copyright (c) 2018 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 unparseable 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(MakeSpan(str)); }
////////////////////////////////////////////////////////////////////////////
// Internal representation //
////////////////////////////////////////////////////////////////////////////
typedef std::vector<uint32_t> KeyPath;
/** Interface for public key objects in descriptors. */
struct PubkeyProvider
{
virtual ~PubkeyProvider() = default;
/** Derive a public key. If key==nullptr, only info is desired. */
virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) const = 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(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint)) + FormatHDKeypath(m_origin.path);
}
public:
OriginPubkeyProvider(KeyOriginInfo info, std::unique_ptr<PubkeyProvider> provider) : m_origin(std::move(info)), m_provider(std::move(provider)) {}
bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) const override
{
if (!m_provider->GetPubKey(pos, arg, key, info)) 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(const CPubKey& pubkey) : m_pubkey(pubkey) {}
bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) const override
{
if (key) *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.begin(), m_pubkey.end()); }
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
{
CExtPubKey m_extkey;
KeyPath m_path;
DeriveType m_derive;
bool GetExtKey(const SigningProvider& arg, CExtKey& ret) const
{
CKey key;
if (!arg.GetKey(m_extkey.pubkey.GetID(), key)) return false;
ret.nDepth = m_extkey.nDepth;
std::copy(m_extkey.vchFingerprint, m_extkey.vchFingerprint + sizeof(ret.vchFingerprint), ret.vchFingerprint);
ret.nChild = m_extkey.nChild;
ret.chaincode = m_extkey.chaincode;
ret.key = key;
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(const CExtPubKey& extkey, KeyPath path, DeriveType derive) : m_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, KeyOriginInfo& info) const override
{
if (key) {
if (IsHardened()) {
CKey priv_key;
if (!GetPrivKey(pos, arg, priv_key)) return false;
*key = priv_key.GetPubKey();
} else {
// TODO: optimize by caching
CExtPubKey extkey = m_extkey;
for (auto entry : m_path) {
extkey.Derive(extkey, entry);
}
if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos);
assert(m_derive != DeriveType::HARDENED);
*key = extkey.pubkey;
}
}
CKeyID keyid = m_extkey.pubkey.GetID();
std::copy(keyid.begin(), keyid.begin() + sizeof(info.fingerprint), info.fingerprint);
info.path = m_path;
if (m_derive == DeriveType::UNHARDENED) info.path.push_back((uint32_t)pos);
if (m_derive == DeriveType::HARDENED) info.path.push_back(((uint32_t)pos) | 0x80000000L);
return true;
}
std::string ToString() const override
{
std::string ret = EncodeExtPubKey(m_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 (!GetExtKey(arg, extkey)) return false;
for (auto entry : m_path) {
extkey.Derive(extkey, entry);
}
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 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;
//! The string name of the descriptor function.
const std::string m_name;
protected:
//! 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<CScript> 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_subdescriptor_arg(std::move(script)), m_name(name) {}
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 override final
{
bool ret = ToStringHelper(&arg, out, true);
out = AddChecksum(out);
return ret;
}
bool ExpandHelper(int pos, const SigningProvider& arg, Span<const unsigned char>* cache_read, std::vector<CScript>& output_scripts, FlatSigningProvider& out, std::vector<unsigned char>* cache_write) 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 we have a cache, we don't need GetPubKey to compute the public key.
// Pass in nullptr to signify only origin info is desired.
if (!p->GetPubKey(pos, arg, cache_read ? nullptr : &entries.back().first, entries.back().second)) return false;
if (cache_read) {
// Cached expanded public key exists, use it.
if (cache_read->size() == 0) return false;
bool compressed = ((*cache_read)[0] == 0x02 || (*cache_read)[0] == 0x03) && cache_read->size() >= 33;
bool uncompressed = ((*cache_read)[0] == 0x04) && cache_read->size() >= 65;
if (!(compressed || uncompressed)) return false;
CPubKey pubkey(cache_read->begin(), cache_read->begin() + (compressed ? 33 : 65));
entries.back().first = pubkey;
*cache_read = cache_read->subspan(compressed ? 33 : 65);
}
if (cache_write) {
cache_write->insert(cache_write->end(), entries.back().first.begin(), entries.back().first.end());
}
}
std::vector<CScript> subscripts;
if (m_subdescriptor_arg) {
FlatSigningProvider subprovider;
if (!m_subdescriptor_arg->ExpandHelper(pos, arg, cache_read, subscripts, subprovider, cache_write)) 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), subscript);
std::vector<CScript> addscripts = MakeScripts(pubkeys, &subscript, 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<CScript>& output_scripts, FlatSigningProvider& out, std::vector<unsigned char>* cache = nullptr) const final
{
return ExpandHelper(pos, provider, nullptr, output_scripts, out, cache);
}
bool ExpandFromCache(int pos, const std::vector<unsigned char>& cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const final
{
Span<const unsigned char> span = MakeSpan(cache);
return ExpandHelper(pos, DUMMY_SIGNING_PROVIDER, &span, output_scripts, out, nullptr) && span.size() == 0;
}
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);
}
}
};
/** 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<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Vector(GetScriptForDestination(m_destination)); }
public:
AddressDescriptor(CTxDestination destination) : DescriptorImpl({}, {}, "addr"), m_destination(std::move(destination)) {}
bool IsSolvable() const final { return false; }
};
/** A parsed raw(H) descriptor. */
class RawDescriptor final : public DescriptorImpl
{
const CScript m_script;
protected:
std::string ToStringExtra() const override { return HexStr(m_script.begin(), m_script.end()); }
std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Vector(m_script); }
public:
RawDescriptor(CScript script) : DescriptorImpl({}, {}, "raw"), m_script(std::move(script)) {}
bool IsSolvable() const final { return false; }
};
/** A parsed pk(P) descriptor. */
class PKDescriptor final : public DescriptorImpl
{
protected:
std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { return Vector(GetScriptForRawPubKey(keys[0])); }
public:
PKDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "pk") {}
};
/** A parsed pkh(P) descriptor. */
class PKHDescriptor final : public DescriptorImpl
{
protected:
std::vector<CScript> 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(GetScriptForDestination(PKHash(id)));
}
public:
PKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "pkh") {}
};
/** A parsed wpkh(P) descriptor. */
class WPKHDescriptor final : public DescriptorImpl
{
protected:
std::vector<CScript> 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(GetScriptForDestination(WitnessV0KeyHash(id)));
}
public:
WPKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Vector(std::move(prov)), {}, "wpkh") {}
};
/** A parsed combo(P) descriptor. */
class ComboDescriptor final : public DescriptorImpl
{
protected:
std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override
{
std::vector<CScript> 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") {}
};
/** 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<CScript> 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(GetScriptForMultisig(m_threshold, sorted_keys));
}
return Vector(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) {}
};
/** A parsed sh(...) descriptor. */
class SHDescriptor final : public DescriptorImpl
{
protected:
std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Vector(GetScriptForDestination(ScriptHash(*script))); }
public:
SHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "sh") {}
};
/** A parsed wsh(...) descriptor. */
class WSHDescriptor final : public DescriptorImpl
{
protected:
std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Vector(GetScriptForDestination(WitnessV0ScriptHash(*script))); }
public:
WSHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "wsh") {}
};
////////////////////////////////////////////////////////////////////////////
// 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()).c_str());
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(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>(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>(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>(extpubkey, std::move(path), type);
}
/** Parse a public key including origin information (if enabled). */
std::unique_ptr<PubkeyProvider> ParsePubkey(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(origin_split[0], permit_uncompressed, out, error);
if (origin_split[0].size() < 1 || origin_split[0][0] != '[') {
error = strprintf("Key origin start '[ character expected but not found, got '%c' instead", 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(origin_split[1], permit_uncompressed, out, error);
if (!provider) return nullptr;
return MakeUnique<OriginPubkeyProvider>(std::move(info), std::move(provider));
}
/** Parse a script in a particular context. */
std::unique_ptr<DescriptorImpl> ParseScript(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(expr, ctx != ParseScriptContext::P2WSH, out, error);
if (!pubkey) return nullptr;
return MakeUnique<PKDescriptor>(std::move(pubkey));
}
if (Func("pkh", expr)) {
auto pubkey = ParsePubkey(expr, ctx != ParseScriptContext::P2WSH, out, error);
if (!pubkey) return nullptr;
return MakeUnique<PKHDescriptor>(std::move(pubkey));
}
if (ctx == ParseScriptContext::TOP && Func("combo", expr)) {
auto pubkey = ParsePubkey(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()).c_str());
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(arg, ctx != ParseScriptContext::P2WSH, out, error);
if (!pk) return nullptr;
script_size += pk->GetSize() + 1;
providers.emplace_back(std::move(pk));
}
if (providers.size() < 1 || 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 > 520) {
error = strprintf("P2SH script is too large, %d bytes is larger than 520 bytes", script_size + 3);
return nullptr;
}
}
return MakeUnique<MultisigDescriptor>(thres, std::move(providers), sorted_multi);
}
if (ctx != ParseScriptContext::P2WSH && Func("wpkh", expr)) {
auto pubkey = ParsePubkey(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(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(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>(pubkey);
KeyOriginInfo info;
if (provider.GetKeyOrigin(pubkey.GetID(), info)) {
return MakeUnique<OriginPubkeyProvider>(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;
txnouttype txntype = Solver(script, data);
if (txntype == TX_PUBKEY) {
CPubKey pubkey(data[0].begin(), data[0].end());
if (pubkey.IsValid()) {
return MakeUnique<PKDescriptor>(InferPubkey(pubkey, ctx, provider));
}
}
if (txntype == TX_PUBKEYHASH) {
uint160 hash(data[0]);
CKeyID keyid(hash);
CPubKey pubkey;
if (provider.GetPubKey(keyid, pubkey)) {
return MakeUnique<PKHDescriptor>(InferPubkey(pubkey, ctx, provider));
}
}
if (txntype == TX_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 == TX_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 == TX_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 == TX_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.data(), descriptor.size());
if (!CheckChecksum(sp, require_checksum, error)) return nullptr;
auto ret = ParseScript(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.data(), descriptor.size());
if (!CheckChecksum(sp, false, error, &ret)) return "";
return ret;
}
std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider)
{
return InferScript(script, ParseScriptContext::TOP, provider);
}
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