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Output descriptors module

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This commit is contained in:
Pieter Wuille 2018-07-04 18:08:19 -07:00
parent e54d76044b
commit fe8a7dcd78
3 changed files with 669 additions and 0 deletions
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2
src/Makefile.am
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@ -158,6 +158,7 @@ BITCOIN_CORE_H = \
rpc/register.h \
rpc/util.h \
scheduler.h \
script/descriptor.h \
script/ismine.h \
script/sigcache.h \
script/sign.h \
@ -387,6 +388,7 @@ libbitcoin_common_a_SOURCES = \
policy/feerate.cpp \
protocol.cpp \
scheduler.cpp \
script/descriptor.cpp \
script/ismine.cpp \
script/sign.cpp \
script/standard.cpp \

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src/script/descriptor.cpp Normal file
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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.h>
#include <utilstrencodings.h>
#include <memory>
#include <string>
#include <vector>
namespace {
////////////////////////////////////////////////////////////////////////////
// Internal representation //
////////////////////////////////////////////////////////////////////////////
typedef std::vector<uint32_t> KeyPath;
std::string FormatKeyPath(const KeyPath& path)
{
std::string ret;
for (auto i : path) {
ret += strprintf("/%i", (i << 1) >> 1);
if (i >> 31) ret += '\'';
}
return ret;
}
/** Interface for public key objects in descriptors. */
struct PubkeyProvider
{
virtual ~PubkeyProvider() = default;
/** Derive a public key. */
virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& out) 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;
};
/** 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& out) const override
{
out = m_pubkey;
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;
}
};
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 + 4, 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& out) const override
{
if (IsHardened()) {
CExtKey key;
if (!GetExtKey(arg, key)) return false;
for (auto entry : m_path) {
key.Derive(key, entry);
}
if (m_derive == DeriveType::UNHARDENED) key.Derive(key, pos);
if (m_derive == DeriveType::HARDENED) key.Derive(key, pos | 0x80000000UL);
out = key.Neuter().pubkey;
} else {
// TODO: optimize by caching
CExtPubKey key = m_extkey;
for (auto entry : m_path) {
key.Derive(key, entry);
}
if (m_derive == DeriveType::UNHARDENED) key.Derive(key, pos);
assert(m_derive != DeriveType::HARDENED);
out = key.pubkey;
}
return true;
}
std::string ToString() const override
{
std::string ret = EncodeExtPubKey(m_extkey) + FormatKeyPath(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) + FormatKeyPath(m_path);
if (IsRange()) {
out += "/*";
if (m_derive == DeriveType::HARDENED) out += '\'';
}
return true;
}
};
/** A parsed addr(A) descriptor. */
class AddressDescriptor final : public Descriptor
{
CTxDestination m_destination;
public:
AddressDescriptor(CTxDestination destination) : m_destination(std::move(destination)) {}
bool IsRange() const override { return false; }
std::string ToString() const override { return "addr(" + EncodeDestination(m_destination) + ")"; }
bool ToPrivateString(const SigningProvider& arg, std::string& out) const override { out = ToString(); return true; }
bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
{
output_scripts = std::vector<CScript>{GetScriptForDestination(m_destination)};
return true;
}
};
/** A parsed raw(H) descriptor. */
class RawDescriptor final : public Descriptor
{
CScript m_script;
public:
RawDescriptor(CScript script) : m_script(std::move(script)) {}
bool IsRange() const override { return false; }
std::string ToString() const override { return "raw(" + HexStr(m_script.begin(), m_script.end()) + ")"; }
bool ToPrivateString(const SigningProvider& arg, std::string& out) const override { out = ToString(); return true; }
bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
{
output_scripts = std::vector<CScript>{m_script};
return true;
}
};
/** A parsed pk(P), pkh(P), or wpkh(P) descriptor. */
class SingleKeyDescriptor final : public Descriptor
{
const std::function<CScript(const CPubKey&)> m_script_fn;
const std::string m_fn_name;
std::unique_ptr<PubkeyProvider> m_provider;
public:
SingleKeyDescriptor(std::unique_ptr<PubkeyProvider> prov, const std::function<CScript(const CPubKey&)>& fn, const std::string& name) : m_script_fn(fn), m_fn_name(name), m_provider(std::move(prov)) {}
bool IsRange() const override { return m_provider->IsRange(); }
std::string ToString() const override { return m_fn_name + "(" + m_provider->ToString() + ")"; }
bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
{
std::string ret;
if (!m_provider->ToPrivateString(arg, ret)) return false;
out = m_fn_name + "(" + std::move(ret) + ")";
return true;
}
bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
{
CPubKey key;
if (!m_provider->GetPubKey(pos, arg, key)) return false;
output_scripts = std::vector<CScript>{m_script_fn(key)};
out.pubkeys.emplace(key.GetID(), std::move(key));
return true;
}
};
CScript P2PKHGetScript(const CPubKey& pubkey) { return GetScriptForDestination(pubkey.GetID()); }
CScript P2PKGetScript(const CPubKey& pubkey) { return GetScriptForRawPubKey(pubkey); }
CScript P2WPKHGetScript(const CPubKey& pubkey) { return GetScriptForDestination(WitnessV0KeyHash(pubkey.GetID())); }
/** A parsed multi(...) descriptor. */
class MultisigDescriptor : public Descriptor
{
int m_threshold;
std::vector<std::unique_ptr<PubkeyProvider>> m_providers;
public:
MultisigDescriptor(int threshold, std::vector<std::unique_ptr<PubkeyProvider>> providers) : m_threshold(threshold), m_providers(std::move(providers)) {}
bool IsRange() const override
{
for (const auto& p : m_providers) {
if (p->IsRange()) return true;
}
return false;
}
std::string ToString() const override
{
std::string ret = strprintf("multi(%i", m_threshold);
for (const auto& p : m_providers) {
ret += "," + p->ToString();
}
return std::move(ret) + ")";
}
bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
{
std::string ret = strprintf("multi(%i", m_threshold);
for (const auto& p : m_providers) {
std::string sub;
if (!p->ToPrivateString(arg, sub)) return false;
ret += "," + std::move(sub);
}
out = std::move(ret) + ")";
return true;
}
bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
{
std::vector<CPubKey> pubkeys;
pubkeys.reserve(m_providers.size());
for (const auto& p : m_providers) {
CPubKey key;
if (!p->GetPubKey(pos, arg, key)) return false;
pubkeys.push_back(key);
}
for (const CPubKey& key : pubkeys) {
out.pubkeys.emplace(key.GetID(), std::move(key));
}
output_scripts = std::vector<CScript>{GetScriptForMultisig(m_threshold, pubkeys)};
return true;
}
};
/** A parsed sh(S) or wsh(S) descriptor. */
class ConvertorDescriptor : public Descriptor
{
const std::function<CScript(const CScript&)> m_convert_fn;
const std::string m_fn_name;
std::unique_ptr<Descriptor> m_descriptor;
public:
ConvertorDescriptor(std::unique_ptr<Descriptor> descriptor, const std::function<CScript(const CScript&)>& fn, const std::string& name) : m_convert_fn(fn), m_fn_name(name), m_descriptor(std::move(descriptor)) {}
bool IsRange() const override { return m_descriptor->IsRange(); }
std::string ToString() const override { return m_fn_name + "(" + m_descriptor->ToString() + ")"; }
bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
{
std::string ret;
if (!m_descriptor->ToPrivateString(arg, ret)) return false;
out = m_fn_name + "(" + std::move(ret) + ")";
return true;
}
bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
{
std::vector<CScript> sub;
if (!m_descriptor->Expand(pos, arg, sub, out)) return false;
output_scripts.clear();
for (const auto& script : sub) {
CScriptID id(script);
out.scripts.emplace(CScriptID(script), script);
output_scripts.push_back(m_convert_fn(script));
}
return true;
}
};
CScript ConvertP2SH(const CScript& script) { return GetScriptForDestination(CScriptID(script)); }
CScript ConvertP2WSH(const CScript& script) { return GetScriptForDestination(WitnessV0ScriptHash(script)); }
/** A parsed combo(P) descriptor. */
class ComboDescriptor final : public Descriptor
{
std::unique_ptr<PubkeyProvider> m_provider;
public:
ComboDescriptor(std::unique_ptr<PubkeyProvider> provider) : m_provider(std::move(provider)) {}
bool IsRange() const override { return m_provider->IsRange(); }
std::string ToString() const override { return "combo(" + m_provider->ToString() + ")"; }
bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
{
std::string ret;
if (!m_provider->ToPrivateString(arg, ret)) return false;
out = "combo(" + std::move(ret) + ")";
return true;
}
bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override
{
CPubKey key;
if (!m_provider->GetPubKey(pos, arg, key)) return false;
CKeyID keyid = key.GetID();
{
CScript p2pk = GetScriptForRawPubKey(key);
CScript p2pkh = GetScriptForDestination(keyid);
output_scripts = std::vector<CScript>{std::move(p2pk), std::move(p2pkh)};
out.pubkeys.emplace(keyid, key);
}
if (key.IsCompressed()) {
CScript p2wpkh = GetScriptForDestination(WitnessV0KeyHash(keyid));
CScriptID p2wpkh_id(p2wpkh);
CScript p2sh_p2wpkh = GetScriptForDestination(p2wpkh_id);
out.scripts.emplace(p2wpkh_id, p2wpkh);
output_scripts.push_back(std::move(p2wpkh));
output_scripts.push_back(std::move(p2sh_p2wpkh));
}
return true;
}
};
////////////////////////////////////////////////////////////////////////////
// Parser //
////////////////////////////////////////////////////////////////////////////
enum class ParseScriptContext {
TOP,
P2SH,
P2WSH,
};
/** Parse a constant. If succesful, sp is updated to skip the constant and return true. */
bool Const(const std::string& str, Span<const char>& sp)
{
if ((size_t)sp.size() >= str.size() && std::equal(str.begin(), str.end(), sp.begin())) {
sp = sp.subspan(str.size());
return true;
}
return false;
}
/** Parse a function call. If succesful, sp is updated to be the function's argument(s). */
bool Func(const std::string& str, Span<const char>& sp)
{
if ((size_t)sp.size() >= str.size() + 2 && sp[str.size()] == '(' && sp[sp.size() - 1] == ')' && std::equal(str.begin(), str.end(), sp.begin())) {
sp = sp.subspan(str.size() + 1, sp.size() - str.size() - 2);
return true;
}
return false;
}
/** Return the expression that sp begins with, and update sp to skip it. */
Span<const char> Expr(Span<const char>& sp)
{
int level = 0;
auto it = sp.begin();
while (it != sp.end()) {
if (*it == '(') {
++level;
} else if (level && *it == ')') {
--level;
} else if (level == 0 && (*it == ')' || *it == ',')) {
break;
}
++it;
}
Span<const char> ret = sp.first(it - sp.begin());
sp = sp.subspan(it - sp.begin());
return ret;
}
/** Split a string on every instance of sep, returning a vector. */
std::vector<Span<const char>> Split(const Span<const char>& sp, char sep)
{
std::vector<Span<const char>> ret;
auto it = sp.begin();
auto start = it;
while (it != sp.end()) {
if (*it == sep) {
ret.emplace_back(start, it);
start = it + 1;
}
++it;
}
ret.emplace_back(start, it);
return ret;
}
/** Parse a key path, being passed a split list of elements (the first element is ignored). */
bool ParseKeyPath(const std::vector<Span<const char>>& split, KeyPath& out)
{
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.first(elem.size() - 1);
hardened = true;
}
uint32_t p;
if (!ParseUInt32(std::string(elem.begin(), elem.end()), &p) || p > 0x7FFFFFFFUL) return false;
out.push_back(p | (((uint32_t)hardened) << 31));
}
return true;
}
std::unique_ptr<PubkeyProvider> ParsePubkey(const Span<const char>& sp, bool permit_uncompressed, FlatSigningProvider& out)
{
auto split = Split(sp, '/');
std::string str(split[0].begin(), split[0].end());
if (split.size() == 1) {
if (IsHex(str)) {
std::vector<unsigned char> data = ParseHex(str);
CPubKey pubkey(data);
if (pubkey.IsFullyValid() && (permit_uncompressed || pubkey.IsCompressed())) return MakeUnique<ConstPubkeyProvider>(pubkey);
}
CKey key = DecodeSecret(str);
if (key.IsValid() && (permit_uncompressed || key.IsCompressed())) {
CPubKey pubkey = key.GetPubKey();
out.keys.emplace(pubkey.GetID(), key);
return MakeUnique<ConstPubkeyProvider>(pubkey);
}
}
CExtKey extkey = DecodeExtKey(str);
CExtPubKey extpubkey = DecodeExtPubKey(str);
if (!extkey.key.IsValid() && !extpubkey.pubkey.IsValid()) 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.pop_back();
type = DeriveType::HARDENED;
}
if (!ParseKeyPath(split, path)) 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 script in a particular context. */
std::unique_ptr<Descriptor> ParseScript(Span<const char>& sp, ParseScriptContext ctx, FlatSigningProvider& out)
{
auto expr = Expr(sp);
if (Func("pk", expr)) {
auto pubkey = ParsePubkey(expr, ctx != ParseScriptContext::P2WSH, out);
if (!pubkey) return nullptr;
return MakeUnique<SingleKeyDescriptor>(std::move(pubkey), P2PKGetScript, "pk");
}
if (Func("pkh", expr)) {
auto pubkey = ParsePubkey(expr, ctx != ParseScriptContext::P2WSH, out);
if (!pubkey) return nullptr;
return MakeUnique<SingleKeyDescriptor>(std::move(pubkey), P2PKHGetScript, "pkh");
}
if (ctx == ParseScriptContext::TOP && Func("combo", expr)) {
auto pubkey = ParsePubkey(expr, true, out);
if (!pubkey) return nullptr;
return MakeUnique<ComboDescriptor>(std::move(pubkey));
}
if (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)) return nullptr;
size_t script_size = 0;
while (expr.size()) {
if (!Const(",", expr)) return nullptr;
auto arg = Expr(expr);
auto pk = ParsePubkey(arg, ctx != ParseScriptContext::P2WSH, out);
if (!pk) return nullptr;
script_size += pk->GetSize() + 1;
providers.emplace_back(std::move(pk));
}
if (providers.size() < 1 || providers.size() > 16 || thres < 1 || thres > providers.size()) return nullptr;
if (ctx == ParseScriptContext::TOP) {
if (providers.size() > 3) return nullptr; // Not more than 3 pubkeys for raw multisig
}
if (ctx == ParseScriptContext::P2SH) {
if (script_size + 3 > 520) return nullptr; // Enforce P2SH script size limit
}
return MakeUnique<MultisigDescriptor>(thres, std::move(providers));
}
if (ctx != ParseScriptContext::P2WSH && Func("wpkh", expr)) {
auto pubkey = ParsePubkey(expr, false, out);
if (!pubkey) return nullptr;
return MakeUnique<SingleKeyDescriptor>(std::move(pubkey), P2WPKHGetScript, "wpkh");
}
if (ctx == ParseScriptContext::TOP && Func("sh", expr)) {
auto desc = ParseScript(expr, ParseScriptContext::P2SH, out);
if (!desc || expr.size()) return nullptr;
return MakeUnique<ConvertorDescriptor>(std::move(desc), ConvertP2SH, "sh");
}
if (ctx != ParseScriptContext::P2WSH && Func("wsh", expr)) {
auto desc = ParseScript(expr, ParseScriptContext::P2WSH, out);
if (!desc || expr.size()) return nullptr;
return MakeUnique<ConvertorDescriptor>(std::move(desc), ConvertP2WSH, "wsh");
}
if (ctx == ParseScriptContext::TOP && Func("addr", expr)) {
CTxDestination dest = DecodeDestination(std::string(expr.begin(), expr.end()));
if (!IsValidDestination(dest)) 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)) return nullptr;
auto bytes = ParseHex(str);
return MakeUnique<RawDescriptor>(CScript(bytes.begin(), bytes.end()));
}
return nullptr;
}
} // namespace
std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out)
{
Span<const char> sp(descriptor.data(), descriptor.size());
auto ret = ParseScript(sp, ParseScriptContext::TOP, out);
if (sp.size() == 0 && ret) return ret;
return nullptr;
}

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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.
#ifndef BITCOIN_SCRIPT_DESCRIPTOR_H
#define BITCOIN_SCRIPT_DESCRIPTOR_H
#include <script/script.h>
#include <script/sign.h>
#include <vector>
// Descriptors are strings that describe a set of scriptPubKeys, together with
// all information necessary to solve them. By combining all information into
// one, they avoid the need to separately import keys and scripts.
//
// Descriptors may be ranged, which occurs when the public keys inside are
// specified in the form of HD chains (xpubs).
//
// Descriptors always represent public information - public keys and scripts -
// but in cases where private keys need to be conveyed along with a descriptor,
// they can be included inside by changing public keys to private keys (WIF
// format), and changing xpubs by xprvs.
//
// 1. Examples
//
// A P2PK descriptor with a fixed public key:
// - pk(0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798)
//
// A P2SH-P2WSH-P2PKH descriptor with a fixed public key:
// - sh(wsh(pkh(02e493dbf1c10d80f3581e4904930b1404cc6c13900ee0758474fa94abe8c4cd13)))
//
// A bare 1-of-2 multisig descriptor:
// - multi(1,022f8bde4d1a07209355b4a7250a5c5128e88b84bddc619ab7cba8d569b240efe4,025cbdf0646e5db4eaa398f365f2ea7a0e3d419b7e0330e39ce92bddedcac4f9bc)
//
// A chain of P2PKH outputs (this needs the corresponding private key to derive):
// - pkh(xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw/1'/2/*)
//
// 2. Grammar description:
//
// X: xpub or xprv encoded extended key
// I: decimal encoded integer
// H: Hex encoded byte array
// A: Address in P2PKH, P2SH, or Bech32 encoding
//
// S (Scripts):
// * pk(P): Pay-to-pubkey (P2PK) output for public key P.
// * pkh(P): Pay-to-pubkey-hash (P2PKH) output for public key P.
// * wpkh(P): Pay-to-witness-pubkey-hash (P2WPKH) output for public key P.
// * sh(S): Pay-to-script-hash (P2SH) output for script S
// * wsh(S): Pay-to-witness-script-hash (P2WSH) output for script S
// * combo(P): combination of P2PK, P2PKH, P2WPKH, and P2SH-P2WPKH for public key P.
// * multi(I,L): k-of-n multisig for given public keys
// * addr(A): Output to address
// * raw(H): scriptPubKey with raw bytes
//
// P (Public keys):
// * H: fixed public key (or WIF-encoded private key)
// * E: extended public key
// * E/*: (ranged) all unhardened direct children of an extended public key
// * E/*': (ranged) all hardened direct children of an extended public key
//
// L (Comma-separated lists of public keys):
// * P
// * L,P
//
// E (Extended public keys):
// * X
// * E/I: unhardened child
// * E/I': hardened child
//
// The top level is S.
/** Interface for parsed descriptor objects. */
struct Descriptor {
virtual ~Descriptor() = default;
/** Whether the expansion of this descriptor depends on the position. */
virtual bool IsRange() const = 0;
/** Convert the descriptor back to a string, undoing parsing. */
virtual std::string ToString() const = 0;
/** Convert the descriptor to a private string. This fails if the provided provider does not have the relevant private keys. */
virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0;
/** Expand a descriptor at a specified position.
*
* pos: the position at which to expand the descriptor. If IsRange() is false, this is ignored.
* provider: the provider to query for private keys in case of hardened derivation.
* output_script: the expanded scriptPubKeys will be put here.
* out: scripts and public keys necessary for solving the expanded scriptPubKeys will be put here (may be equal to provider).
*/
virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
};
/** Parse a descriptor string. Included private keys are put in out. Returns nullptr if parsing fails. */
std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out);
#endif // BITCOIN_SCRIPT_DESCRIPTOR_H