/root/bitcoin/src/script/descriptor.h

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// Copyright (c) 2018-2021 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 <outputtype.h>
#include <script/script.h>
#include <script/sign.h>
#include <script/signingprovider.h>

#include <optional>
#include <vector>

using ExtPubKeyMap = std::unordered_map<uint32_t, CExtPubKey>;

/** Cache for single descriptor's derived extended pubkeys */
class DescriptorCache {
private:
    /** Map key expression index -> map of (key derivation index -> xpub) */
    std::unordered_map<uint32_t, ExtPubKeyMap> m_derived_xpubs;
    /** Map key expression index -> parent xpub */
    ExtPubKeyMap m_parent_xpubs;
    /** Map key expression index -> last hardened xpub */
    ExtPubKeyMap m_last_hardened_xpubs;

public:
    /** Cache a parent xpub
     *
     * @param[in] key_exp_pos Position of the key expression within the descriptor
     * @param[in] xpub The CExtPubKey to cache
     */
    void CacheParentExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub);
    /** Retrieve a cached parent xpub
     *
     * @param[in] key_exp_pos Position of the key expression within the descriptor
     * @param[out] xpub The CExtPubKey to get from cache
     */
    bool GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;
    /** Cache an xpub derived at an index
     *
     * @param[in] key_exp_pos Position of the key expression within the descriptor
     * @param[in] der_index Derivation index of the xpub
     * @param[in] xpub The CExtPubKey to cache
     */
    void CacheDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, const CExtPubKey& xpub);
    /** Retrieve a cached xpub derived at an index
     *
     * @param[in] key_exp_pos Position of the key expression within the descriptor
     * @param[in] der_index Derivation index of the xpub
     * @param[out] xpub The CExtPubKey to get from cache
     */
    bool GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const;
    /** Cache a last hardened xpub
     *
     * @param[in] key_exp_pos Position of the key expression within the descriptor
     * @param[in] xpub The CExtPubKey to cache
     */
    void CacheLastHardenedExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub);
    /** Retrieve a cached last hardened xpub
     *
     * @param[in] key_exp_pos Position of the key expression within the descriptor
     * @param[out] xpub The CExtPubKey to get from cache
     */
    bool GetCachedLastHardenedExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;

    /** Retrieve all cached parent xpubs */
    ExtPubKeyMap GetCachedParentExtPubKeys() const;
    /** Retrieve all cached derived xpubs */
    std::unordered_map<uint32_t, ExtPubKeyMap> GetCachedDerivedExtPubKeys() const;
    /** Retrieve all cached last hardened xpubs */
    ExtPubKeyMap GetCachedLastHardenedExtPubKeys() const;

    /** Combine another DescriptorCache into this one.
     * Returns a cache containing the items from the other cache unknown to current cache
     */
    DescriptorCache MergeAndDiff(const DescriptorCache& other);
};

/** \brief Interface for parsed descriptor objects.
 *
 * 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.
 *
 * Reference documentation about the descriptor language can be found in
 * doc/descriptors.md.
 */
struct Descriptor {
    virtual ~Descriptor() = default;

    /** Whether the expansion of this descriptor depends on the position. */
    virtual bool IsRange() const = 0;

    /** Whether this descriptor has all information about signing ignoring lack of private keys.
     *  This is true for all descriptors except ones that use `raw` or `addr` constructions. */
    virtual bool IsSolvable() const = 0;

    /** Convert the descriptor back to a string, undoing parsing. */
    virtual std::string ToString(bool compat_format=false) const = 0;

    /** Whether this descriptor will return one scriptPubKey or multiple (aka is or is not combo) */
    virtual bool IsSingleType() 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;

    /** Convert the descriptor to a normalized string. Normalized descriptors have the xpub at the last hardened step. This fails if the provided provider does not have the private keys to derive that xpub. */
    virtual bool ToNormalizedString(const SigningProvider& provider, std::string& out, const DescriptorCache* cache = nullptr) const = 0;

    /** Expand a descriptor at a specified position.
     *
     * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
     * @param[in] provider The provider to query for private keys in case of hardened derivation.
     * @param[out] output_scripts The expanded scriptPubKeys.
     * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`).
     * @param[out] write_cache Cache data necessary to evaluate the descriptor at this point without access to private keys.
     */
    virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache = nullptr) const = 0;

    /** Expand a descriptor at a specified position using cached expansion data.
     *
     * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
     * @param[in] read_cache Cached expansion data.
     * @param[out] output_scripts The expanded scriptPubKeys.
     * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`).
     */
    virtual bool ExpandFromCache(int pos, const DescriptorCache& read_cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;

    /** Expand the private key for a descriptor at a specified position, if possible.
     *
     * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
     * @param[in] provider The provider to query for the private keys.
     * @param[out] out Any private keys available for the specified `pos`.
     */
    virtual void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const = 0;

    /** @return The OutputType of the scriptPubKey(s) produced by this descriptor. Or nullopt if indeterminate (multiple or none) */
    virtual std::optional<OutputType> GetOutputType() const = 0;

    /** Get the size of the scriptPubKey for this descriptor. */
    virtual std::optional<int64_t> ScriptSize() const = 0;

    /** Get the maximum size of a satisfaction for this descriptor, in weight units.
     *
     * @param use_max_sig Whether to assume ECDSA signatures will have a high-r.
     */
    virtual std::optional<int64_t> MaxSatisfactionWeight(bool use_max_sig) const = 0;

    /** Get the maximum size number of stack elements for satisfying this descriptor. */
    virtual std::optional<int64_t> MaxSatisfactionElems() const = 0;

    /** Return all (extended) public keys for this descriptor, including any from subdescriptors.
     *
     * @param[out] pubkeys Any public keys
     * @param[out] ext_pubs Any extended public keys
     */
    virtual void GetPubKeys(std::set<CPubKey>& pubkeys, std::set<CExtPubKey>& ext_pubs) const = 0;
};

/** Parse a `descriptor` string. Included private keys are put in `out`.
 *
 * If the descriptor has a checksum, it must be valid. If `require_checksum`
 * is set, the checksum is mandatory - otherwise it is optional.
 *
 * If a parse error occurs, or the checksum is missing/invalid, or anything
 * else is wrong, an empty vector is returned.
 */
std::vector<std::unique_ptr<Descriptor>> Parse(const std::string& descriptor, FlatSigningProvider& out, std::string& error, bool require_checksum = false);

/** Get the checksum for a `descriptor`.
 *
 * - If it already has one, and it is correct, return the checksum in the input.
 * - If it already has one that is wrong, return "".
 * - If it does not already have one, return the checksum that would need to be added.
 */
std::string GetDescriptorChecksum(const std::string& descriptor);

/** Find a descriptor for the specified `script`, using information from `provider` where possible.
 *
 * A non-ranged descriptor which only generates the specified script will be returned in all
 * circumstances.
 *
 * For public keys with key origin information, this information will be preserved in the returned
 * descriptor.
 *
 * - If all information for solving `script` is present in `provider`, a descriptor will be returned
 *   which is IsSolvable() and encapsulates said information.
 * - Failing that, if `script` corresponds to a known address type, an "addr()" descriptor will be
 *   returned (which is not IsSolvable()).
 * - Failing that, a "raw()" descriptor is returned.
 */
std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider);

/** Unique identifier that may not change over time, unless explicitly marked as not backwards compatible.
*   This is not part of BIP 380, not guaranteed to be interoperable and should not be exposed to the user.
*/
uint256 DescriptorID(const Descriptor& desc);

#endif // BITCOIN_SCRIPT_DESCRIPTOR_H

Coverage Report

Created: 2025-02-21 14:37

Line	Count	Source (jump to first uncovered line)
1		// Copyright (c) 2018-2021 The Bitcoin Core developers
2		// Distributed under the MIT software license, see the accompanying
3		// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5		#ifndef BITCOIN_SCRIPT_DESCRIPTOR_H
6		#define BITCOIN_SCRIPT_DESCRIPTOR_H
7
8		#include <outputtype.h>
9		#include <script/script.h>
10		#include <script/sign.h>
11		#include <script/signingprovider.h>
12
13		#include <optional>
14		#include <vector>
15
16		using ExtPubKeyMap = std::unordered_map<uint32_t, CExtPubKey>;
17
18		/** Cache for single descriptor's derived extended pubkeys */
19		class DescriptorCache {
20		private:
21		/** Map key expression index -> map of (key derivation index -> xpub) */
22		std::unordered_map<uint32_t, ExtPubKeyMap> m_derived_xpubs;
23		/** Map key expression index -> parent xpub */
24		ExtPubKeyMap m_parent_xpubs;
25		/** Map key expression index -> last hardened xpub */
26		ExtPubKeyMap m_last_hardened_xpubs;
27
28		public:
29		/** Cache a parent xpub
30		*
31		* @param[in] key_exp_pos Position of the key expression within the descriptor
32		* @param[in] xpub The CExtPubKey to cache
33		*/
34		void CacheParentExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub);
35		/** Retrieve a cached parent xpub
36		*
37		* @param[in] key_exp_pos Position of the key expression within the descriptor
38		* @param[out] xpub The CExtPubKey to get from cache
39		*/
40		bool GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;
41		/** Cache an xpub derived at an index
42		*
43		* @param[in] key_exp_pos Position of the key expression within the descriptor
44		* @param[in] der_index Derivation index of the xpub
45		* @param[in] xpub The CExtPubKey to cache
46		*/
47		void CacheDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, const CExtPubKey& xpub);
48		/** Retrieve a cached xpub derived at an index
49		*
50		* @param[in] key_exp_pos Position of the key expression within the descriptor
51		* @param[in] der_index Derivation index of the xpub
52		* @param[out] xpub The CExtPubKey to get from cache
53		*/
54		bool GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const;
55		/** Cache a last hardened xpub
56		*
57		* @param[in] key_exp_pos Position of the key expression within the descriptor
58		* @param[in] xpub The CExtPubKey to cache
59		*/
60		void CacheLastHardenedExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub);
61		/** Retrieve a cached last hardened xpub
62		*
63		* @param[in] key_exp_pos Position of the key expression within the descriptor
64		* @param[out] xpub The CExtPubKey to get from cache
65		*/
66		bool GetCachedLastHardenedExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;
67
68		/** Retrieve all cached parent xpubs */
69		ExtPubKeyMap GetCachedParentExtPubKeys() const;
70		/** Retrieve all cached derived xpubs */
71		std::unordered_map<uint32_t, ExtPubKeyMap> GetCachedDerivedExtPubKeys() const;
72		/** Retrieve all cached last hardened xpubs */
73		ExtPubKeyMap GetCachedLastHardenedExtPubKeys() const;
74
75		/** Combine another DescriptorCache into this one.
76		* Returns a cache containing the items from the other cache unknown to current cache
77		*/
78		DescriptorCache MergeAndDiff(const DescriptorCache& other);
79		};
80
81		/** \brief Interface for parsed descriptor objects.
82		*
83		* Descriptors are strings that describe a set of scriptPubKeys, together with
84		* all information necessary to solve them. By combining all information into
85		* one, they avoid the need to separately import keys and scripts.
86		*
87		* Descriptors may be ranged, which occurs when the public keys inside are
88		* specified in the form of HD chains (xpubs).
89		*
90		* Descriptors always represent public information - public keys and scripts -
91		* but in cases where private keys need to be conveyed along with a descriptor,
92		* they can be included inside by changing public keys to private keys (WIF
93		* format), and changing xpubs by xprvs.
94		*
95		* Reference documentation about the descriptor language can be found in
96		* doc/descriptors.md.
97		*/
98		struct Descriptor {
99	0	virtual ~Descriptor() = default;
100
101		/** Whether the expansion of this descriptor depends on the position. */
102		virtual bool IsRange() const = 0;
103
104		/** Whether this descriptor has all information about signing ignoring lack of private keys.
105		* This is true for all descriptors except ones that use `raw` or `addr` constructions. */
106		virtual bool IsSolvable() const = 0;
107
108		/** Convert the descriptor back to a string, undoing parsing. */
109		virtual std::string ToString(bool compat_format=false) const = 0;
110
111		/** Whether this descriptor will return one scriptPubKey or multiple (aka is or is not combo) */
112		virtual bool IsSingleType() const = 0;
113
114		/** Convert the descriptor to a private string. This fails if the provided provider does not have the relevant private keys. */
115		virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0;
116
117		/** Convert the descriptor to a normalized string. Normalized descriptors have the xpub at the last hardened step. This fails if the provided provider does not have the private keys to derive that xpub. */
118		virtual bool ToNormalizedString(const SigningProvider& provider, std::string& out, const DescriptorCache* cache = nullptr) const = 0;
119
120		/** Expand a descriptor at a specified position.
121		*
122		* @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
123		* @param[in] provider The provider to query for private keys in case of hardened derivation.
124		* @param[out] output_scripts The expanded scriptPubKeys.
125		* @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`).
126		* @param[out] write_cache Cache data necessary to evaluate the descriptor at this point without access to private keys.
127		*/
128		virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache = nullptr) const = 0;
129
130		/** Expand a descriptor at a specified position using cached expansion data.
131		*
132		* @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
133		* @param[in] read_cache Cached expansion data.
134		* @param[out] output_scripts The expanded scriptPubKeys.
135		* @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`).
136		*/
137		virtual bool ExpandFromCache(int pos, const DescriptorCache& read_cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
138
139		/** Expand the private key for a descriptor at a specified position, if possible.
140		*
141		* @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
142		* @param[in] provider The provider to query for the private keys.
143		* @param[out] out Any private keys available for the specified `pos`.
144		*/
145		virtual void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const = 0;
146
147		/** @return The OutputType of the scriptPubKey(s) produced by this descriptor. Or nullopt if indeterminate (multiple or none) */
148		virtual std::optional<OutputType> GetOutputType() const = 0;
149
150		/** Get the size of the scriptPubKey for this descriptor. */
151		virtual std::optional<int64_t> ScriptSize() const = 0;
152
153		/** Get the maximum size of a satisfaction for this descriptor, in weight units.
154		*
155		* @param use_max_sig Whether to assume ECDSA signatures will have a high-r.
156		*/
157		virtual std::optional<int64_t> MaxSatisfactionWeight(bool use_max_sig) const = 0;
158
159		/** Get the maximum size number of stack elements for satisfying this descriptor. */
160		virtual std::optional<int64_t> MaxSatisfactionElems() const = 0;
161
162		/** Return all (extended) public keys for this descriptor, including any from subdescriptors.
163		*
164		* @param[out] pubkeys Any public keys
165		* @param[out] ext_pubs Any extended public keys
166		*/
167		virtual void GetPubKeys(std::set<CPubKey>& pubkeys, std::set<CExtPubKey>& ext_pubs) const = 0;
168		};
169
170		/** Parse a `descriptor` string. Included private keys are put in `out`.
171		*
172		* If the descriptor has a checksum, it must be valid. If `require_checksum`
173		* is set, the checksum is mandatory - otherwise it is optional.
174		*
175		* If a parse error occurs, or the checksum is missing/invalid, or anything
176		* else is wrong, an empty vector is returned.
177		*/
178		std::vector<std::unique_ptr<Descriptor>> Parse(const std::string& descriptor, FlatSigningProvider& out, std::string& error, bool require_checksum = false);
179
180		/** Get the checksum for a `descriptor`.
181		*
182		* - If it already has one, and it is correct, return the checksum in the input.
183		* - If it already has one that is wrong, return "".
184		* - If it does not already have one, return the checksum that would need to be added.
185		*/
186		std::string GetDescriptorChecksum(const std::string& descriptor);
187
188		/** Find a descriptor for the specified `script`, using information from `provider` where possible.
189		*
190		* A non-ranged descriptor which only generates the specified script will be returned in all
191		* circumstances.
192		*
193		* For public keys with key origin information, this information will be preserved in the returned
194		* descriptor.
195		*
196		* - If all information for solving `script` is present in `provider`, a descriptor will be returned
197		* which is IsSolvable() and encapsulates said information.
198		* - Failing that, if `script` corresponds to a known address type, an "addr()" descriptor will be
199		* returned (which is not IsSolvable()).
200		* - Failing that, a "raw()" descriptor is returned.
201		*/
202		std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider);
203
204		/** Unique identifier that may not change over time, unless explicitly marked as not backwards compatible.
205		* This is not part of BIP 380, not guaranteed to be interoperable and should not be exposed to the user.
206		*/
207		uint256 DescriptorID(const Descriptor& desc);
208
209		#endif // BITCOIN_SCRIPT_DESCRIPTOR_H