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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 [ + - ][ + - : 8250 : 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, `nullptr` is returned.
177 : : */
178 : : 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
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