aboutsummaryrefslogtreecommitdiff
path: root/src/script/descriptor.cpp
blob: 532a8028a2895049fd5610ae4d16d4dee9f816ed (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
// 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/bip32.h>
#include <util/system.h>
#include <util/strencodings.h>

#include <memory>
#include <string>
#include <vector>

namespace {

////////////////////////////////////////////////////////////////////////////
// Internal representation                                                //
////////////////////////////////////////////////////////////////////////////

typedef std::vector<uint32_t> KeyPath;

/** Interface for public key objects in descriptors. */
struct PubkeyProvider
{
    virtual ~PubkeyProvider() = default;

    /** Derive a public key. If key==nullptr, only info is desired. */
    virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) 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;
};

class OriginPubkeyProvider final : public PubkeyProvider
{
    KeyOriginInfo m_origin;
    std::unique_ptr<PubkeyProvider> m_provider;

    std::string OriginString() const
    {
        return HexStr(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint)) + FormatHDKeypath(m_origin.path);
    }

public:
    OriginPubkeyProvider(KeyOriginInfo info, std::unique_ptr<PubkeyProvider> provider) : m_origin(std::move(info)), m_provider(std::move(provider)) {}
    bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) const override
    {
        if (!m_provider->GetPubKey(pos, arg, key, info)) return false;
        std::copy(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint), info.fingerprint);
        info.path.insert(info.path.begin(), m_origin.path.begin(), m_origin.path.end());
        return true;
    }
    bool IsRange() const override { return m_provider->IsRange(); }
    size_t GetSize() const override { return m_provider->GetSize(); }
    std::string ToString() const override { return "[" + OriginString() + "]" + m_provider->ToString(); }
    bool ToPrivateString(const SigningProvider& arg, std::string& ret) const override
    {
        std::string sub;
        if (!m_provider->ToPrivateString(arg, sub)) return false;
        ret = "[" + OriginString() + "]" + std::move(sub);
        return true;
    }
};

/** 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* key, KeyOriginInfo& info) const override
    {
        if (key) *key = m_pubkey;
        info.path.clear();
        CKeyID keyid = m_pubkey.GetID();
        std::copy(keyid.begin(), keyid.begin() + sizeof(info.fingerprint), info.fingerprint);
        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 + sizeof(ret.vchFingerprint), 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* key, KeyOriginInfo& info) const override
    {
        if (key) {
            if (IsHardened()) {
                CExtKey extkey;
                if (!GetExtKey(arg, extkey)) return false;
                for (auto entry : m_path) {
                    extkey.Derive(extkey, entry);
                }
                if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos);
                if (m_derive == DeriveType::HARDENED) extkey.Derive(extkey, pos | 0x80000000UL);
                *key = extkey.Neuter().pubkey;
            } else {
                // TODO: optimize by caching
                CExtPubKey extkey = m_extkey;
                for (auto entry : m_path) {
                    extkey.Derive(extkey, entry);
                }
                if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos);
                assert(m_derive != DeriveType::HARDENED);
                *key = extkey.pubkey;
            }
        }
        CKeyID keyid = m_extkey.pubkey.GetID();
        std::copy(keyid.begin(), keyid.begin() + sizeof(info.fingerprint), info.fingerprint);
        info.path = m_path;
        if (m_derive == DeriveType::UNHARDENED) info.path.push_back((uint32_t)pos);
        if (m_derive == DeriveType::HARDENED) info.path.push_back(((uint32_t)pos) | 0x80000000L);
        return true;
    }
    std::string ToString() const override
    {
        std::string ret = EncodeExtPubKey(m_extkey) + FormatHDKeypath(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) + FormatHDKeypath(m_path);
        if (IsRange()) {
            out += "/*";
            if (m_derive == DeriveType::HARDENED) out += '\'';
        }
        return true;
    }
};

/** Base class for all Descriptor implementations. */
class DescriptorImpl : public Descriptor
{
    //! Public key arguments for this descriptor (size 1 for PK, PKH, WPKH; any size of Multisig).
    const std::vector<std::unique_ptr<PubkeyProvider>> m_pubkey_args;
    //! The sub-descriptor argument (nullptr for everything but SH and WSH).
    const std::unique_ptr<DescriptorImpl> m_script_arg;
    //! The string name of the descriptor function.
    const std::string m_name;

protected:
    //! Return a serialization of anything except pubkey and script arguments, to be prepended to those.
    virtual std::string ToStringExtra() const { return ""; }

    /** A helper function to construct the scripts for this descriptor.
     *
     *  This function is invoked once for every CScript produced by evaluating
     *  m_script_arg, or just once in case m_script_arg is nullptr.

     *  @param pubkeys The evaluations of the m_pubkey_args field.
     *  @param script The evaluation of m_script_arg (or nullptr when m_script_arg is nullptr).
     *  @param out A FlatSigningProvider to put scripts or public keys in that are necessary to the solver.
     *             The script arguments to this function are automatically added, as is the origin info of the provided pubkeys.
     *  @return A vector with scriptPubKeys for this descriptor.
     */
    virtual std::vector<CScript> MakeScripts(const std::vector<CPubKey>& pubkeys, const CScript* script, FlatSigningProvider& out) const = 0;

public:
    DescriptorImpl(std::vector<std::unique_ptr<PubkeyProvider>> pubkeys, std::unique_ptr<DescriptorImpl> script, const std::string& name) : m_pubkey_args(std::move(pubkeys)), m_script_arg(std::move(script)), m_name(name) {}

    bool IsSolvable() const override
    {
        if (m_script_arg) {
            if (!m_script_arg->IsSolvable()) return false;
        }
        return true;
    }

    bool IsRange() const final
    {
        for (const auto& pubkey : m_pubkey_args) {
            if (pubkey->IsRange()) return true;
        }
        if (m_script_arg) {
            if (m_script_arg->IsRange()) return true;
        }
        return false;
    }

    bool ToStringHelper(const SigningProvider* arg, std::string& out, bool priv) const
    {
        std::string extra = ToStringExtra();
        size_t pos = extra.size() > 0 ? 1 : 0;
        std::string ret = m_name + "(" + extra;
        for (const auto& pubkey : m_pubkey_args) {
            if (pos++) ret += ",";
            std::string tmp;
            if (priv) {
                if (!pubkey->ToPrivateString(*arg, tmp)) return false;
            } else {
                tmp = pubkey->ToString();
            }
            ret += std::move(tmp);
        }
        if (m_script_arg) {
            if (pos++) ret += ",";
            std::string tmp;
            if (!m_script_arg->ToStringHelper(arg, tmp, priv)) return false;
            ret += std::move(tmp);
        }
        out = std::move(ret) + ")";
        return true;
    }

    std::string ToString() const final
    {
        std::string ret;
        ToStringHelper(nullptr, ret, false);
        return ret;
    }

    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override final { return ToStringHelper(&arg, out, true); }

    bool ExpandHelper(int pos, const SigningProvider& arg, Span<const unsigned char>* cache_read, std::vector<CScript>& output_scripts, FlatSigningProvider& out, std::vector<unsigned char>* cache_write) const
    {
        std::vector<std::pair<CPubKey, KeyOriginInfo>> entries;
        entries.reserve(m_pubkey_args.size());

        // Construct temporary data in `entries` and `subscripts`, to avoid producing output in case of failure.
        for (const auto& p : m_pubkey_args) {
            entries.emplace_back();
            if (!p->GetPubKey(pos, arg, cache_read ? nullptr : &entries.back().first, entries.back().second)) return false;
            if (cache_read) {
                // Cached expanded public key exists, use it.
                if (cache_read->size() == 0) return false;
                bool compressed = ((*cache_read)[0] == 0x02 || (*cache_read)[0] == 0x03) && cache_read->size() >= 33;
                bool uncompressed = ((*cache_read)[0] == 0x04) && cache_read->size() >= 65;
                if (!(compressed || uncompressed)) return false;
                CPubKey pubkey(cache_read->begin(), cache_read->begin() + (compressed ? 33 : 65));
                entries.back().first = pubkey;
                *cache_read = cache_read->subspan(compressed ? 33 : 65);
            }
            if (cache_write) {
                cache_write->insert(cache_write->end(), entries.back().first.begin(), entries.back().first.end());
            }
        }
        std::vector<CScript> subscripts;
        if (m_script_arg) {
            FlatSigningProvider subprovider;
            if (!m_script_arg->ExpandHelper(pos, arg, cache_read, subscripts, subprovider, cache_write)) return false;
            out = Merge(out, subprovider);
        }

        std::vector<CPubKey> pubkeys;
        pubkeys.reserve(entries.size());
        for (auto& entry : entries) {
            pubkeys.push_back(entry.first);
            out.origins.emplace(entry.first.GetID(), std::move(entry.second));
        }
        if (m_script_arg) {
            for (const auto& subscript : subscripts) {
                out.scripts.emplace(CScriptID(subscript), subscript);
                std::vector<CScript> addscripts = MakeScripts(pubkeys, &subscript, out);
                for (auto& addscript : addscripts) {
                    output_scripts.push_back(std::move(addscript));
                }
            }
        } else {
            output_scripts = MakeScripts(pubkeys, nullptr, out);
        }
        return true;
    }

    bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out, std::vector<unsigned char>* cache = nullptr) const final
    {
        return ExpandHelper(pos, provider, nullptr, output_scripts, out, cache);
    }

    bool ExpandFromCache(int pos, const std::vector<unsigned char>& cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const final
    {
        Span<const unsigned char> span = MakeSpan(cache);
        return ExpandHelper(pos, DUMMY_SIGNING_PROVIDER, &span, output_scripts, out, nullptr) && span.size() == 0;
    }
};

/** Construct a vector with one element, which is moved into it. */
template<typename T>
std::vector<T> Singleton(T elem)
{
    std::vector<T> ret;
    ret.emplace_back(std::move(elem));
    return ret;
}

/** A parsed addr(A) descriptor. */
class AddressDescriptor final : public DescriptorImpl
{
    const CTxDestination m_destination;
protected:
    std::string ToStringExtra() const override { return EncodeDestination(m_destination); }
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(m_destination)); }
public:
    AddressDescriptor(CTxDestination destination) : DescriptorImpl({}, {}, "addr"), m_destination(std::move(destination)) {}
    bool IsSolvable() const final { return false; }
};

/** A parsed raw(H) descriptor. */
class RawDescriptor final : public DescriptorImpl
{
    const CScript m_script;
protected:
    std::string ToStringExtra() const override { return HexStr(m_script.begin(), m_script.end()); }
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript*, FlatSigningProvider&) const override { return Singleton(m_script); }
public:
    RawDescriptor(CScript script) : DescriptorImpl({}, {}, "raw"), m_script(std::move(script)) {}
    bool IsSolvable() const final { return false; }
};

/** A parsed pk(P) descriptor. */
class PKDescriptor final : public DescriptorImpl
{
protected:
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { return Singleton(GetScriptForRawPubKey(keys[0])); }
public:
    PKDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "pk") {}
};

/** A parsed pkh(P) descriptor. */
class PKHDescriptor final : public DescriptorImpl
{
protected:
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override
    {
        CKeyID id = keys[0].GetID();
        out.pubkeys.emplace(id, keys[0]);
        return Singleton(GetScriptForDestination(id));
    }
public:
    PKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "pkh") {}
};

/** A parsed wpkh(P) descriptor. */
class WPKHDescriptor final : public DescriptorImpl
{
protected:
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override
    {
        CKeyID id = keys[0].GetID();
        out.pubkeys.emplace(id, keys[0]);
        return Singleton(GetScriptForDestination(WitnessV0KeyHash(id)));
    }
public:
    WPKHDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "wpkh") {}
};

/** A parsed combo(P) descriptor. */
class ComboDescriptor final : public DescriptorImpl
{
protected:
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider& out) const override
    {
        std::vector<CScript> ret;
        CKeyID id = keys[0].GetID();
        out.pubkeys.emplace(id, keys[0]);
        ret.emplace_back(GetScriptForRawPubKey(keys[0])); // P2PK
        ret.emplace_back(GetScriptForDestination(id)); // P2PKH
        if (keys[0].IsCompressed()) {
            CScript p2wpkh = GetScriptForDestination(WitnessV0KeyHash(id));
            out.scripts.emplace(CScriptID(p2wpkh), p2wpkh);
            ret.emplace_back(p2wpkh);
            ret.emplace_back(GetScriptForDestination(CScriptID(p2wpkh))); // P2SH-P2WPKH
        }
        return ret;
    }
public:
    ComboDescriptor(std::unique_ptr<PubkeyProvider> prov) : DescriptorImpl(Singleton(std::move(prov)), {}, "combo") {}
};

/** A parsed multi(...) descriptor. */
class MultisigDescriptor final : public DescriptorImpl
{
    const int m_threshold;
protected:
    std::string ToStringExtra() const override { return strprintf("%i", m_threshold); }
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>& keys, const CScript*, FlatSigningProvider&) const override { return Singleton(GetScriptForMultisig(m_threshold, keys)); }
public:
    MultisigDescriptor(int threshold, std::vector<std::unique_ptr<PubkeyProvider>> providers) : DescriptorImpl(std::move(providers), {}, "multi"), m_threshold(threshold) {}
};

/** A parsed sh(...) descriptor. */
class SHDescriptor final : public DescriptorImpl
{
protected:
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(CScriptID(*script))); }
public:
    SHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "sh") {}
};

/** A parsed wsh(...) descriptor. */
class WSHDescriptor final : public DescriptorImpl
{
protected:
    std::vector<CScript> MakeScripts(const std::vector<CPubKey>&, const CScript* script, FlatSigningProvider&) const override { return Singleton(GetScriptForDestination(WitnessV0ScriptHash(*script))); }
public:
    WSHDescriptor(std::unique_ptr<DescriptorImpl> desc) : DescriptorImpl({}, std::move(desc), "wsh") {}
};

////////////////////////////////////////////////////////////////////////////
// Parser                                                                 //
////////////////////////////////////////////////////////////////////////////

enum class ParseScriptContext {
    TOP,
    P2SH,
    P2WSH,
};

/** Parse a constant. If successful, 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 successful, 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). */
NODISCARD 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.size() - 1] == 'h')) {
            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;
}

/** Parse a public key that excludes origin information. */
std::unique_ptr<PubkeyProvider> ParsePubkeyInner(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.back() == MakeSpan("*h").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 public key including origin information (if enabled). */
std::unique_ptr<PubkeyProvider> ParsePubkey(const Span<const char>& sp, bool permit_uncompressed, FlatSigningProvider& out)
{
    auto origin_split = Split(sp, ']');
    if (origin_split.size() > 2) return nullptr;
    if (origin_split.size() == 1) return ParsePubkeyInner(origin_split[0], permit_uncompressed, out);
    if (origin_split[0].size() < 1 || origin_split[0][0] != '[') return nullptr;
    auto slash_split = Split(origin_split[0].subspan(1), '/');
    if (slash_split[0].size() != 8) return nullptr;
    std::string fpr_hex = std::string(slash_split[0].begin(), slash_split[0].end());
    if (!IsHex(fpr_hex)) return nullptr;
    auto fpr_bytes = ParseHex(fpr_hex);
    KeyOriginInfo info;
    static_assert(sizeof(info.fingerprint) == 4, "Fingerprint must be 4 bytes");
    assert(fpr_bytes.size() == 4);
    std::copy(fpr_bytes.begin(), fpr_bytes.end(), info.fingerprint);
    if (!ParseKeyPath(slash_split, info.path)) return nullptr;
    auto provider = ParsePubkeyInner(origin_split[1], permit_uncompressed, out);
    if (!provider) return nullptr;
    return MakeUnique<OriginPubkeyProvider>(std::move(info), std::move(provider));
}

/** Parse a script in a particular context. */
std::unique_ptr<DescriptorImpl> 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<PKDescriptor>(std::move(pubkey));
    }
    if (Func("pkh", expr)) {
        auto pubkey = ParsePubkey(expr, ctx != ParseScriptContext::P2WSH, out);
        if (!pubkey) return nullptr;
        return MakeUnique<PKHDescriptor>(std::move(pubkey));
    }
    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<WPKHDescriptor>(std::move(pubkey));
    }
    if (ctx == ParseScriptContext::TOP && Func("sh", expr)) {
        auto desc = ParseScript(expr, ParseScriptContext::P2SH, out);
        if (!desc || expr.size()) return nullptr;
        return MakeUnique<SHDescriptor>(std::move(desc));
    }
    if (ctx != ParseScriptContext::P2WSH && Func("wsh", expr)) {
        auto desc = ParseScript(expr, ParseScriptContext::P2WSH, out);
        if (!desc || expr.size()) return nullptr;
        return MakeUnique<WSHDescriptor>(std::move(desc));
    }
    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;
}

std::unique_ptr<PubkeyProvider> InferPubkey(const CPubKey& pubkey, ParseScriptContext, const SigningProvider& provider)
{
    std::unique_ptr<PubkeyProvider> key_provider = MakeUnique<ConstPubkeyProvider>(pubkey);
    KeyOriginInfo info;
    if (provider.GetKeyOrigin(pubkey.GetID(), info)) {
        return MakeUnique<OriginPubkeyProvider>(std::move(info), std::move(key_provider));
    }
    return key_provider;
}

std::unique_ptr<DescriptorImpl> InferScript(const CScript& script, ParseScriptContext ctx, const SigningProvider& provider)
{
    std::vector<std::vector<unsigned char>> data;
    txnouttype txntype = Solver(script, data);

    if (txntype == TX_PUBKEY) {
        CPubKey pubkey(data[0].begin(), data[0].end());
        if (pubkey.IsValid()) {
            return MakeUnique<PKDescriptor>(InferPubkey(pubkey, ctx, provider));
        }
    }
    if (txntype == TX_PUBKEYHASH) {
        uint160 hash(data[0]);
        CKeyID keyid(hash);
        CPubKey pubkey;
        if (provider.GetPubKey(keyid, pubkey)) {
            return MakeUnique<PKHDescriptor>(InferPubkey(pubkey, ctx, provider));
        }
    }
    if (txntype == TX_WITNESS_V0_KEYHASH && ctx != ParseScriptContext::P2WSH) {
        uint160 hash(data[0]);
        CKeyID keyid(hash);
        CPubKey pubkey;
        if (provider.GetPubKey(keyid, pubkey)) {
            return MakeUnique<WPKHDescriptor>(InferPubkey(pubkey, ctx, provider));
        }
    }
    if (txntype == TX_MULTISIG) {
        std::vector<std::unique_ptr<PubkeyProvider>> providers;
        for (size_t i = 1; i + 1 < data.size(); ++i) {
            CPubKey pubkey(data[i].begin(), data[i].end());
            providers.push_back(InferPubkey(pubkey, ctx, provider));
        }
        return MakeUnique<MultisigDescriptor>((int)data[0][0], std::move(providers));
    }
    if (txntype == TX_SCRIPTHASH && ctx == ParseScriptContext::TOP) {
        uint160 hash(data[0]);
        CScriptID scriptid(hash);
        CScript subscript;
        if (provider.GetCScript(scriptid, subscript)) {
            auto sub = InferScript(subscript, ParseScriptContext::P2SH, provider);
            if (sub) return MakeUnique<SHDescriptor>(std::move(sub));
        }
    }
    if (txntype == TX_WITNESS_V0_SCRIPTHASH && ctx != ParseScriptContext::P2WSH) {
        CScriptID scriptid;
        CRIPEMD160().Write(data[0].data(), data[0].size()).Finalize(scriptid.begin());
        CScript subscript;
        if (provider.GetCScript(scriptid, subscript)) {
            auto sub = InferScript(subscript, ParseScriptContext::P2WSH, provider);
            if (sub) return MakeUnique<WSHDescriptor>(std::move(sub));
        }
    }

    CTxDestination dest;
    if (ExtractDestination(script, dest)) {
        if (GetScriptForDestination(dest) == script) {
            return MakeUnique<AddressDescriptor>(std::move(dest));
        }
    }

    return MakeUnique<RawDescriptor>(script);
}

} // 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 std::unique_ptr<Descriptor>(std::move(ret));
    return nullptr;
}

std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider)
{
    return InferScript(script, ParseScriptContext::TOP, provider);
}