fuzz coverage

// 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;

    /** Whether this descriptor only produces single key scripts (i.e. pk(), pkh(), wpkh(), sh() and wsh() nested of those, and combo())

     *  TODO: Remove this method once legacy wallets are removed as it is only necessary for importmulti.

     */

    virtual bool IsSingleKey() 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