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1 : : // Copyright (c) 2018-present 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 <pubkey.h>
10 : : #include <uint256.h>
11 : :
12 : : #include <cstddef>
13 : : #include <cstdint>
14 : : #include <memory>
15 : : #include <optional>
16 : : #include <set>
17 : : #include <string>
18 : : #include <string_view>
19 : : #include <unordered_map>
20 : : #include <vector>
21 : :
22 : : class CScript;
23 : : class SigningProvider;
24 : : struct FlatSigningProvider;
25 : :
26 : : using ExtPubKeyMap = std::unordered_map<uint32_t, CExtPubKey>;
27 : :
28 : : /** Cache for single descriptor's derived extended pubkeys */
29 : : class DescriptorCache {
30 : : private:
31 : : /** Map key expression index -> map of (key derivation index -> xpub) */
32 : : std::unordered_map<uint32_t, ExtPubKeyMap> m_derived_xpubs;
33 : : /** Map key expression index -> parent xpub */
34 : : ExtPubKeyMap m_parent_xpubs;
35 : : /** Map key expression index -> last hardened xpub */
36 : : ExtPubKeyMap m_last_hardened_xpubs;
37 : :
38 : : public:
39 : : /** Cache a parent xpub
40 : : *
41 : : * @param[in] key_exp_pos Position of the key expression within the descriptor
42 : : * @param[in] xpub The CExtPubKey to cache
43 : : */
44 : : void CacheParentExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub);
45 : : /** Retrieve a cached parent xpub
46 : : *
47 : : * @param[in] key_exp_pos Position of the key expression within the descriptor
48 : : * @param[out] xpub The CExtPubKey to get from cache
49 : : */
50 : : bool GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;
51 : : /** Cache an xpub derived at an index
52 : : *
53 : : * @param[in] key_exp_pos Position of the key expression within the descriptor
54 : : * @param[in] der_index Derivation index of the xpub
55 : : * @param[in] xpub The CExtPubKey to cache
56 : : */
57 : : void CacheDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, const CExtPubKey& xpub);
58 : : /** Retrieve a cached xpub derived at an index
59 : : *
60 : : * @param[in] key_exp_pos Position of the key expression within the descriptor
61 : : * @param[in] der_index Derivation index of the xpub
62 : : * @param[out] xpub The CExtPubKey to get from cache
63 : : */
64 : : bool GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const;
65 : : /** Cache a last hardened xpub
66 : : *
67 : : * @param[in] key_exp_pos Position of the key expression within the descriptor
68 : : * @param[in] xpub The CExtPubKey to cache
69 : : */
70 : : void CacheLastHardenedExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub);
71 : : /** Retrieve a cached last hardened xpub
72 : : *
73 : : * @param[in] key_exp_pos Position of the key expression within the descriptor
74 : : * @param[out] xpub The CExtPubKey to get from cache
75 : : */
76 : : bool GetCachedLastHardenedExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;
77 : :
78 : : /** Retrieve all cached parent xpubs */
79 : : ExtPubKeyMap GetCachedParentExtPubKeys() const;
80 : : /** Retrieve all cached derived xpubs */
81 : : std::unordered_map<uint32_t, ExtPubKeyMap> GetCachedDerivedExtPubKeys() const;
82 : : /** Retrieve all cached last hardened xpubs */
83 : : ExtPubKeyMap GetCachedLastHardenedExtPubKeys() const;
84 : :
85 : : /** Combine another DescriptorCache into this one.
86 : : * Returns a cache containing the items from the other cache unknown to current cache
87 : : */
88 : : DescriptorCache MergeAndDiff(const DescriptorCache& other);
89 : : };
90 : :
91 : : /** \brief Interface for parsed descriptor objects.
92 : : *
93 : : * Descriptors are strings that describe a set of scriptPubKeys, together with
94 : : * all information necessary to solve them. By combining all information into
95 : : * one, they avoid the need to separately import keys and scripts.
96 : : *
97 : : * Descriptors may be ranged, which occurs when the public keys inside are
98 : : * specified in the form of HD chains (xpubs).
99 : : *
100 : : * Descriptors always represent public information - public keys and scripts -
101 : : * but in cases where private keys need to be conveyed along with a descriptor,
102 : : * they can be included inside by changing public keys to private keys (WIF
103 : : * format), and changing xpubs by xprvs.
104 : : *
105 : : * Reference documentation about the descriptor language can be found in
106 : : * doc/descriptors.md.
107 : : */
108 [ - + - + : 401532 : struct Descriptor {
- + ][ - +
- + - + ]
109 : 0 : virtual ~Descriptor() = default;
110 : :
111 : : /** Whether the expansion of this descriptor depends on the position. */
112 : : virtual bool IsRange() const = 0;
113 : :
114 : : /** Whether this descriptor has all information about signing ignoring lack of private keys.
115 : : * This is true for all descriptors except ones that use `raw` or `addr` constructions. */
116 : : virtual bool IsSolvable() const = 0;
117 : :
118 : : /** Convert the descriptor back to a string, undoing parsing. */
119 : : virtual std::string ToString(bool compat_format=false) const = 0;
120 : :
121 : : /** Whether this descriptor will return at most one scriptPubKey or multiple (aka is or is not combo) */
122 : : virtual bool IsSingleType() const = 0;
123 : :
124 : : /** Whether the given provider has all private keys required by this descriptor.
125 : : * @return `false` if the descriptor doesn't have any keys or subdescriptors,
126 : : * or if the provider does not have all private keys required by
127 : : * the descriptor.
128 : : */
129 : : virtual bool HavePrivateKeys(const SigningProvider& provider) const = 0;
130 : :
131 : : /** Convert the descriptor to a private string. This uses public keys if the relevant private keys are not in the SigningProvider.
132 : : * If none of the relevant private keys are available, the output string in the "out" parameter will not contain any private key information,
133 : : * and this function will return "false".
134 : : * @param[in] provider The SigningProvider to query for private keys.
135 : : * @param[out] out The resulting descriptor string, containing private keys if available.
136 : : * @returns true if at least one private key available.
137 : : */
138 : : virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0;
139 : :
140 : : /** 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. */
141 : : virtual bool ToNormalizedString(const SigningProvider& provider, std::string& out, const DescriptorCache* cache = nullptr) const = 0;
142 : :
143 : : /** Expand a descriptor at a specified position.
144 : : *
145 : : * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
146 : : * @param[in] provider The provider to query for private keys in case of hardened derivation.
147 : : * @param[out] output_scripts The expanded scriptPubKeys.
148 : : * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`).
149 : : * @param[out] write_cache Cache data necessary to evaluate the descriptor at this point without access to private keys.
150 : : */
151 : : virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache = nullptr) const = 0;
152 : :
153 : : /** Expand a descriptor at a specified position using cached expansion data.
154 : : *
155 : : * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
156 : : * @param[in] read_cache Cached expansion data.
157 : : * @param[out] output_scripts The expanded scriptPubKeys.
158 : : * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`).
159 : : */
160 : : virtual bool ExpandFromCache(int pos, const DescriptorCache& read_cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
161 : :
162 : : /** Expand the private key for a descriptor at a specified position, if possible.
163 : : *
164 : : * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
165 : : * @param[in] provider The provider to query for the private keys.
166 : : * @param[out] out Any private keys available for the specified `pos`.
167 : : */
168 : : virtual void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const = 0;
169 : :
170 : : /** @return The OutputType of the scriptPubKey(s) produced by this descriptor. Or nullopt if indeterminate (multiple or none) */
171 : : virtual std::optional<OutputType> GetOutputType() const = 0;
172 : :
173 : : /** Get the size of the scriptPubKey for this descriptor. */
174 : : virtual std::optional<int64_t> ScriptSize() const = 0;
175 : :
176 : : /** Get the maximum size of a satisfaction for this descriptor, in weight units.
177 : : *
178 : : * @param use_max_sig Whether to assume ECDSA signatures will have a high-r.
179 : : */
180 : : virtual std::optional<int64_t> MaxSatisfactionWeight(bool use_max_sig) const = 0;
181 : :
182 : : /** Get the maximum size number of stack elements for satisfying this descriptor. */
183 : : virtual std::optional<int64_t> MaxSatisfactionElems() const = 0;
184 : :
185 : : /** Return all (extended) public keys for this descriptor, including any from subdescriptors.
186 : : *
187 : : * @param[out] pubkeys Any public keys
188 : : * @param[out] ext_pubs Any extended public keys
189 : : */
190 : : virtual void GetPubKeys(std::set<CPubKey>& pubkeys, std::set<CExtPubKey>& ext_pubs) const = 0;
191 : :
192 : : /** Whether this descriptor produces any scripts with the Expand functions */
193 : : virtual bool HasScripts() const = 0;
194 : :
195 : : /** Semantic/safety warnings (includes subdescriptors). */
196 : : virtual std::vector<std::string> Warnings() const = 0;
197 : :
198 : : /** Get the maximum key expression index. Used only for tests */
199 : : virtual uint32_t GetMaxKeyExpr() const = 0;
200 : :
201 : : /** Get the number of key expressions in this descriptor. Used only for tests */
202 : : virtual size_t GetKeyCount() const = 0;
203 : : };
204 : :
205 : : /** Parse a `descriptor` string. Included private keys are put in `out`.
206 : : *
207 : : * If the descriptor has a checksum, it must be valid. If `require_checksum`
208 : : * is set, the checksum is mandatory - otherwise it is optional.
209 : : *
210 : : * If a parse error occurs, or the checksum is missing/invalid, or anything
211 : : * else is wrong, an empty vector is returned.
212 : : */
213 : : std::vector<std::unique_ptr<Descriptor>> Parse(std::string_view descriptor, FlatSigningProvider& out, std::string& error, bool require_checksum = false);
214 : :
215 : : /** Get the checksum for a `descriptor`.
216 : : *
217 : : * - If it already has one, and it is correct, return the checksum in the input.
218 : : * - If it already has one that is wrong, return "".
219 : : * - If it does not already have one, return the checksum that would need to be added.
220 : : */
221 : : std::string GetDescriptorChecksum(const std::string& descriptor);
222 : :
223 : : /** Find a descriptor for the specified `script`, using information from `provider` where possible.
224 : : *
225 : : * A non-ranged descriptor which only generates the specified script will be returned in all
226 : : * circumstances.
227 : : *
228 : : * For public keys with key origin information, this information will be preserved in the returned
229 : : * descriptor.
230 : : *
231 : : * - If all information for solving `script` is present in `provider`, a descriptor will be returned
232 : : * which is IsSolvable() and encapsulates said information.
233 : : * - Failing that, if `script` corresponds to a known address type, an "addr()" descriptor will be
234 : : * returned (which is not IsSolvable()).
235 : : * - Failing that, a "raw()" descriptor is returned.
236 : : */
237 : : std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider);
238 : :
239 : : /** Unique identifier that may not change over time, unless explicitly marked as not backwards compatible.
240 : : * This is not part of BIP 380, not guaranteed to be interoperable and should not be exposed to the user.
241 : : */
242 : : uint256 DescriptorID(const Descriptor& desc);
243 : :
244 : : #endif // BITCOIN_SCRIPT_DESCRIPTOR_H
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