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1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
2 : : // Copyright (c) 2009-2022 The Bitcoin Core developers
3 : : // Distributed under the MIT software license, see the accompanying
4 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 : :
6 : : #include <script/keyorigin.h>
7 : : #include <script/interpreter.h>
8 : : #include <script/signingprovider.h>
9 : :
10 : : #include <logging.h>
11 : :
12 : 2 : const SigningProvider& DUMMY_SIGNING_PROVIDER = SigningProvider();
13 : :
14 : : template<typename M, typename K, typename V>
15 : 541763 : bool LookupHelper(const M& map, const K& key, V& value)
16 : : {
17 : 541763 : auto it = map.find(key);
18 [ + - ][ + - ]: 541763 : if (it != map.end()) {
[ + + ][ + + ]
[ + - ]
19 : 442655 : value = it->second;
20 : 442655 : return true;
21 : : }
22 : 99108 : return false;
23 : 541763 : }
24 : :
25 : 0 : bool HidingSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const
26 : : {
27 : 0 : return m_provider->GetCScript(scriptid, script);
28 : : }
29 : :
30 : 0 : bool HidingSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const
31 : : {
32 : 0 : return m_provider->GetPubKey(keyid, pubkey);
33 : : }
34 : :
35 : 0 : bool HidingSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const
36 : : {
37 [ # # ]: 0 : if (m_hide_secret) return false;
38 : 0 : return m_provider->GetKey(keyid, key);
39 : 0 : }
40 : :
41 : 0 : bool HidingSigningProvider::GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const
42 : : {
43 [ # # ]: 0 : if (m_hide_origin) return false;
44 : 0 : return m_provider->GetKeyOrigin(keyid, info);
45 : 0 : }
46 : :
47 : 0 : bool HidingSigningProvider::GetTaprootSpendData(const XOnlyPubKey& output_key, TaprootSpendData& spenddata) const
48 : : {
49 : 0 : return m_provider->GetTaprootSpendData(output_key, spenddata);
50 : : }
51 : 0 : bool HidingSigningProvider::GetTaprootBuilder(const XOnlyPubKey& output_key, TaprootBuilder& builder) const
52 : : {
53 : 0 : return m_provider->GetTaprootBuilder(output_key, builder);
54 : : }
55 : :
56 : 288 : bool FlatSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const { return LookupHelper(scripts, scriptid, script); }
57 : 1330 : bool FlatSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const { return LookupHelper(pubkeys, keyid, pubkey); }
58 : 475501 : bool FlatSigningProvider::GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const
59 : : {
60 : 475501 : std::pair<CPubKey, KeyOriginInfo> out;
61 [ + - ]: 475501 : bool ret = LookupHelper(origins, keyid, out);
62 [ + + ]: 475501 : if (ret) info = std::move(out.second);
63 : 475501 : return ret;
64 : 475501 : }
65 : 60288 : bool FlatSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const { return LookupHelper(keys, keyid, key); }
66 : 4356 : bool FlatSigningProvider::GetTaprootSpendData(const XOnlyPubKey& output_key, TaprootSpendData& spenddata) const
67 : : {
68 : 4356 : TaprootBuilder builder;
69 [ + - ][ + - ]: 4356 : if (LookupHelper(tr_trees, output_key, builder)) {
70 [ + - ]: 4356 : spenddata = builder.GetSpendData();
71 : 4356 : return true;
72 : : }
73 : 0 : return false;
74 : 4356 : }
75 : 0 : bool FlatSigningProvider::GetTaprootBuilder(const XOnlyPubKey& output_key, TaprootBuilder& builder) const
76 : : {
77 : 0 : return LookupHelper(tr_trees, output_key, builder);
78 : : }
79 : :
80 : 449244 : FlatSigningProvider& FlatSigningProvider::Merge(FlatSigningProvider&& b)
81 : : {
82 : 449244 : scripts.merge(b.scripts);
83 : 449244 : pubkeys.merge(b.pubkeys);
84 : 449244 : keys.merge(b.keys);
85 : 449244 : origins.merge(b.origins);
86 : 449244 : tr_trees.merge(b.tr_trees);
87 : 449244 : return *this;
88 : : }
89 : :
90 : 0 : void FillableSigningProvider::ImplicitlyLearnRelatedKeyScripts(const CPubKey& pubkey)
91 : : {
92 : 0 : AssertLockHeld(cs_KeyStore);
93 : 0 : CKeyID key_id = pubkey.GetID();
94 : : // This adds the redeemscripts necessary to detect P2WPKH and P2SH-P2WPKH
95 : : // outputs. Technically P2WPKH outputs don't have a redeemscript to be
96 : : // spent. However, our current IsMine logic requires the corresponding
97 : : // P2SH-P2WPKH redeemscript to be present in the wallet in order to accept
98 : : // payment even to P2WPKH outputs.
99 : : // Also note that having superfluous scripts in the keystore never hurts.
100 : : // They're only used to guide recursion in signing and IsMine logic - if
101 : : // a script is present but we can't do anything with it, it has no effect.
102 : : // "Implicitly" refers to fact that scripts are derived automatically from
103 : : // existing keys, and are present in memory, even without being explicitly
104 : : // loaded (e.g. from a file).
105 [ # # ]: 0 : if (pubkey.IsCompressed()) {
106 [ # # ]: 0 : CScript script = GetScriptForDestination(WitnessV0KeyHash(key_id));
107 : : // This does not use AddCScript, as it may be overridden.
108 [ # # ]: 0 : CScriptID id(script);
109 [ # # ]: 0 : mapScripts[id] = std::move(script);
110 : 0 : }
111 : 0 : }
112 : :
113 : 0 : bool FillableSigningProvider::GetPubKey(const CKeyID &address, CPubKey &vchPubKeyOut) const
114 : : {
115 : 0 : CKey key;
116 [ # # ][ # # ]: 0 : if (!GetKey(address, key)) {
117 : 0 : return false;
118 : : }
119 [ # # ]: 0 : vchPubKeyOut = key.GetPubKey();
120 : 0 : return true;
121 : 0 : }
122 : :
123 : 0 : bool FillableSigningProvider::AddKeyPubKey(const CKey& key, const CPubKey &pubkey)
124 : : {
125 : 0 : LOCK(cs_KeyStore);
126 [ # # ][ # # ]: 0 : mapKeys[pubkey.GetID()] = key;
[ # # ]
127 [ # # ]: 0 : ImplicitlyLearnRelatedKeyScripts(pubkey);
128 : : return true;
129 : 0 : }
130 : :
131 : 0 : bool FillableSigningProvider::HaveKey(const CKeyID &address) const
132 : : {
133 : 0 : LOCK(cs_KeyStore);
134 [ # # ]: 0 : return mapKeys.count(address) > 0;
135 : 0 : }
136 : :
137 : 0 : std::set<CKeyID> FillableSigningProvider::GetKeys() const
138 : : {
139 : 0 : LOCK(cs_KeyStore);
140 : 0 : std::set<CKeyID> set_address;
141 [ # # ]: 0 : for (const auto& mi : mapKeys) {
142 [ # # ]: 0 : set_address.insert(mi.first);
143 : : }
144 : 0 : return set_address;
145 [ # # ]: 0 : }
146 : :
147 : 0 : bool FillableSigningProvider::GetKey(const CKeyID &address, CKey &keyOut) const
148 : : {
149 : 0 : LOCK(cs_KeyStore);
150 [ # # ]: 0 : KeyMap::const_iterator mi = mapKeys.find(address);
151 [ # # ]: 0 : if (mi != mapKeys.end()) {
152 [ # # ]: 0 : keyOut = mi->second;
153 : 0 : return true;
154 : : }
155 : 0 : return false;
156 : 0 : }
157 : :
158 : 0 : bool FillableSigningProvider::AddCScript(const CScript& redeemScript)
159 : : {
160 [ # # ]: 0 : if (redeemScript.size() > MAX_SCRIPT_ELEMENT_SIZE)
161 : 0 : return error("FillableSigningProvider::AddCScript(): redeemScripts > %i bytes are invalid", MAX_SCRIPT_ELEMENT_SIZE);
162 : :
163 : 0 : LOCK(cs_KeyStore);
164 [ # # ][ # # ]: 0 : mapScripts[CScriptID(redeemScript)] = redeemScript;
[ # # ]
165 : 0 : return true;
166 : 0 : }
167 : :
168 : 0 : bool FillableSigningProvider::HaveCScript(const CScriptID& hash) const
169 : : {
170 : 0 : LOCK(cs_KeyStore);
171 [ # # ]: 0 : return mapScripts.count(hash) > 0;
172 : 0 : }
173 : :
174 : 0 : std::set<CScriptID> FillableSigningProvider::GetCScripts() const
175 : : {
176 : 0 : LOCK(cs_KeyStore);
177 : 0 : std::set<CScriptID> set_script;
178 [ # # ]: 0 : for (const auto& mi : mapScripts) {
179 [ # # ]: 0 : set_script.insert(mi.first);
180 : : }
181 : 0 : return set_script;
182 [ # # ]: 0 : }
183 : :
184 : 0 : bool FillableSigningProvider::GetCScript(const CScriptID &hash, CScript& redeemScriptOut) const
185 : : {
186 : 0 : LOCK(cs_KeyStore);
187 [ # # ]: 0 : ScriptMap::const_iterator mi = mapScripts.find(hash);
188 [ # # ]: 0 : if (mi != mapScripts.end())
189 : : {
190 [ # # ]: 0 : redeemScriptOut = (*mi).second;
191 : 0 : return true;
192 : : }
193 : 0 : return false;
194 : 0 : }
195 : :
196 : 0 : CKeyID GetKeyForDestination(const SigningProvider& store, const CTxDestination& dest)
197 : : {
198 : : // Only supports destinations which map to single public keys:
199 : : // P2PKH, P2WPKH, P2SH-P2WPKH, P2TR
200 [ # # ]: 0 : if (auto id = std::get_if<PKHash>(&dest)) {
201 : 0 : return ToKeyID(*id);
202 : : }
203 [ # # ]: 0 : if (auto witness_id = std::get_if<WitnessV0KeyHash>(&dest)) {
204 : 0 : return ToKeyID(*witness_id);
205 : : }
206 [ # # ]: 0 : if (auto script_hash = std::get_if<ScriptHash>(&dest)) {
207 : 0 : CScript script;
208 [ # # ]: 0 : CScriptID script_id = ToScriptID(*script_hash);
209 [ # # ]: 0 : CTxDestination inner_dest;
210 [ # # ][ # # ]: 0 : if (store.GetCScript(script_id, script) && ExtractDestination(script, inner_dest)) {
[ # # ][ # # ]
211 [ # # ]: 0 : if (auto inner_witness_id = std::get_if<WitnessV0KeyHash>(&inner_dest)) {
212 [ # # ]: 0 : return ToKeyID(*inner_witness_id);
213 : : }
214 : 0 : }
215 [ # # ]: 0 : }
216 [ # # ]: 0 : if (auto output_key = std::get_if<WitnessV1Taproot>(&dest)) {
217 : 0 : TaprootSpendData spenddata;
218 [ # # ]: 0 : CPubKey pub;
219 [ # # ][ # # ]: 0 : if (store.GetTaprootSpendData(*output_key, spenddata)
220 [ # # ][ # # ]: 0 : && !spenddata.internal_key.IsNull()
221 [ # # ][ # # ]: 0 : && spenddata.merkle_root.IsNull()
222 [ # # ][ # # ]: 0 : && store.GetPubKeyByXOnly(spenddata.internal_key, pub)) {
223 [ # # ]: 0 : return pub.GetID();
224 : : }
225 [ # # ]: 0 : }
226 : 0 : return CKeyID();
227 : 0 : }
228 : :
229 : 198394 : void MultiSigningProvider::AddProvider(std::unique_ptr<SigningProvider> provider)
230 : : {
231 : 198394 : m_providers.push_back(std::move(provider));
232 : 198394 : }
233 : :
234 : 0 : bool MultiSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const
235 : : {
236 [ # # ]: 0 : for (const auto& provider: m_providers) {
237 [ # # ]: 0 : if (provider->GetCScript(scriptid, script)) return true;
238 : : }
239 : 0 : return false;
240 : 0 : }
241 : :
242 : 0 : bool MultiSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const
243 : : {
244 [ # # ]: 0 : for (const auto& provider: m_providers) {
245 [ # # ]: 0 : if (provider->GetPubKey(keyid, pubkey)) return true;
246 : : }
247 : 0 : return false;
248 : 0 : }
249 : :
250 : :
251 : 102178 : bool MultiSigningProvider::GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const
252 : : {
253 [ + - ]: 102178 : for (const auto& provider: m_providers) {
254 [ + - ]: 102178 : if (provider->GetKeyOrigin(keyid, info)) return true;
255 : : }
256 : 0 : return false;
257 : 102178 : }
258 : :
259 : 0 : bool MultiSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const
260 : : {
261 [ # # ]: 0 : for (const auto& provider: m_providers) {
262 [ # # ]: 0 : if (provider->GetKey(keyid, key)) return true;
263 : : }
264 : 0 : return false;
265 : 0 : }
266 : :
267 : 0 : bool MultiSigningProvider::GetTaprootSpendData(const XOnlyPubKey& output_key, TaprootSpendData& spenddata) const
268 : : {
269 [ # # ]: 0 : for (const auto& provider: m_providers) {
270 [ # # ]: 0 : if (provider->GetTaprootSpendData(output_key, spenddata)) return true;
271 : : }
272 : 0 : return false;
273 : 0 : }
274 : :
275 : 0 : bool MultiSigningProvider::GetTaprootBuilder(const XOnlyPubKey& output_key, TaprootBuilder& builder) const
276 : : {
277 [ # # ]: 0 : for (const auto& provider: m_providers) {
278 [ # # ]: 0 : if (provider->GetTaprootBuilder(output_key, builder)) return true;
279 : : }
280 : 0 : return false;
281 : 0 : }
282 : :
283 : 0 : /*static*/ TaprootBuilder::NodeInfo TaprootBuilder::Combine(NodeInfo&& a, NodeInfo&& b)
284 : : {
285 : 0 : NodeInfo ret;
286 : : /* Iterate over all tracked leaves in a, add b's hash to their Merkle branch, and move them to ret. */
287 [ # # ]: 0 : for (auto& leaf : a.leaves) {
288 [ # # ]: 0 : leaf.merkle_branch.push_back(b.hash);
289 [ # # ]: 0 : ret.leaves.emplace_back(std::move(leaf));
290 : : }
291 : : /* Iterate over all tracked leaves in b, add a's hash to their Merkle branch, and move them to ret. */
292 [ # # ]: 0 : for (auto& leaf : b.leaves) {
293 [ # # ]: 0 : leaf.merkle_branch.push_back(a.hash);
294 [ # # ]: 0 : ret.leaves.emplace_back(std::move(leaf));
295 : : }
296 [ # # ][ # # ]: 0 : ret.hash = ComputeTapbranchHash(a.hash, b.hash);
[ # # ]
297 : 0 : return ret;
298 [ # # ]: 0 : }
299 : :
300 : 0 : void TaprootSpendData::Merge(TaprootSpendData other)
301 : : {
302 : : // TODO: figure out how to better deal with conflicting information
303 : : // being merged.
304 [ # # ][ # # ]: 0 : if (internal_key.IsNull() && !other.internal_key.IsNull()) {
305 : 0 : internal_key = other.internal_key;
306 : 0 : }
307 [ # # ][ # # ]: 0 : if (merkle_root.IsNull() && !other.merkle_root.IsNull()) {
308 : 0 : merkle_root = other.merkle_root;
309 : 0 : }
310 [ # # ]: 0 : for (auto& [key, control_blocks] : other.scripts) {
311 : 0 : scripts[key].merge(std::move(control_blocks));
312 : : }
313 : 0 : }
314 : :
315 : 0 : void TaprootBuilder::Insert(TaprootBuilder::NodeInfo&& node, int depth)
316 : : {
317 [ # # ][ # # ]: 0 : assert(depth >= 0 && (size_t)depth <= TAPROOT_CONTROL_MAX_NODE_COUNT);
318 : : /* We cannot insert a leaf at a lower depth while a deeper branch is unfinished. Doing
319 : : * so would mean the Add() invocations do not correspond to a DFS traversal of a
320 : : * binary tree. */
321 [ # # ]: 0 : if ((size_t)depth + 1 < m_branch.size()) {
322 : 0 : m_valid = false;
323 : 0 : return;
324 : : }
325 : : /* As long as an entry in the branch exists at the specified depth, combine it and propagate up.
326 : : * The 'node' variable is overwritten here with the newly combined node. */
327 [ # # ][ # # ]: 0 : while (m_valid && m_branch.size() > (size_t)depth && m_branch[depth].has_value()) {
[ # # ]
328 : 0 : node = Combine(std::move(node), std::move(*m_branch[depth]));
329 : 0 : m_branch.pop_back();
330 [ # # ]: 0 : if (depth == 0) m_valid = false; /* Can't propagate further up than the root */
331 : 0 : --depth;
332 : : }
333 [ # # ]: 0 : if (m_valid) {
334 : : /* Make sure the branch is big enough to place the new node. */
335 [ # # ]: 0 : if (m_branch.size() <= (size_t)depth) m_branch.resize((size_t)depth + 1);
336 [ # # ]: 0 : assert(!m_branch[depth].has_value());
337 : 0 : m_branch[depth] = std::move(node);
338 : 0 : }
339 : 0 : }
340 : :
341 : 2 : /*static*/ bool TaprootBuilder::ValidDepths(const std::vector<int>& depths)
342 : : {
343 : 2 : std::vector<bool> branch;
344 [ - + ]: 2 : for (int depth : depths) {
345 : : // This inner loop corresponds to effectively the same logic on branch
346 : : // as what Insert() performs on the m_branch variable. Instead of
347 : : // storing a NodeInfo object, just remember whether or not there is one
348 : : // at that depth.
349 [ # # ][ # # ]: 0 : if (depth < 0 || (size_t)depth > TAPROOT_CONTROL_MAX_NODE_COUNT) return false;
350 [ # # ]: 0 : if ((size_t)depth + 1 < branch.size()) return false;
351 [ # # ][ # # ]: 0 : while (branch.size() > (size_t)depth && branch[depth]) {
[ # # ]
352 [ # # ]: 0 : branch.pop_back();
353 [ # # ]: 0 : if (depth == 0) return false;
354 : 0 : --depth;
355 : : }
356 [ # # ][ # # ]: 0 : if (branch.size() <= (size_t)depth) branch.resize((size_t)depth + 1);
357 [ # # ][ # # ]: 0 : assert(!branch[depth]);
358 [ # # ]: 0 : branch[depth] = true;
359 : : }
360 : : // And this check corresponds to the IsComplete() check on m_branch.
361 [ + - ][ # # ]: 2 : return branch.size() == 0 || (branch.size() == 1 && branch[0]);
[ # # ]
362 : 2 : }
363 : :
364 : 0 : TaprootBuilder& TaprootBuilder::Add(int depth, Span<const unsigned char> script, int leaf_version, bool track)
365 : : {
366 [ # # ]: 0 : assert((leaf_version & ~TAPROOT_LEAF_MASK) == 0);
367 [ # # ]: 0 : if (!IsValid()) return *this;
368 : : /* Construct NodeInfo object with leaf hash and (if track is true) also leaf information. */
369 : 0 : NodeInfo node;
370 [ # # ]: 0 : node.hash = ComputeTapleafHash(leaf_version, script);
371 : : // due to bug in clang-tidy-17:
372 : : // NOLINTNEXTLINE(modernize-use-emplace)
373 [ # # ][ # # ]: 0 : if (track) node.leaves.emplace_back(LeafInfo{std::vector<unsigned char>(script.begin(), script.end()), leaf_version, {}});
[ # # ]
374 : : /* Insert into the branch. */
375 [ # # ]: 0 : Insert(std::move(node), depth);
376 : 0 : return *this;
377 : 0 : }
378 : :
379 : 0 : TaprootBuilder& TaprootBuilder::AddOmitted(int depth, const uint256& hash)
380 : : {
381 [ # # ]: 0 : if (!IsValid()) return *this;
382 : : /* Construct NodeInfo object with the hash directly, and insert it into the branch. */
383 : 0 : NodeInfo node;
384 : 0 : node.hash = hash;
385 [ # # ]: 0 : Insert(std::move(node), depth);
386 : 0 : return *this;
387 : 0 : }
388 : :
389 : 10059 : TaprootBuilder& TaprootBuilder::Finalize(const XOnlyPubKey& internal_key)
390 : : {
391 : : /* Can only call this function when IsComplete() is true. */
392 [ + - ]: 10059 : assert(IsComplete());
393 : 10059 : m_internal_key = internal_key;
394 [ - + ]: 10059 : auto ret = m_internal_key.CreateTapTweak(m_branch.size() == 0 ? nullptr : &m_branch[0]->hash);
395 [ - + ]: 10059 : assert(ret.has_value());
396 : 10059 : std::tie(m_output_key, m_parity) = *ret;
397 : 10059 : return *this;
398 : : }
399 : :
400 : 10059 : WitnessV1Taproot TaprootBuilder::GetOutput() { return WitnessV1Taproot{m_output_key}; }
401 : :
402 : 4356 : TaprootSpendData TaprootBuilder::GetSpendData() const
403 : : {
404 [ + - ]: 4356 : assert(IsComplete());
405 [ + - ]: 4356 : assert(m_output_key.IsFullyValid());
406 : 4356 : TaprootSpendData spd;
407 [ - + ][ + - ]: 4356 : spd.merkle_root = m_branch.size() == 0 ? uint256() : m_branch[0]->hash;
408 : 4356 : spd.internal_key = m_internal_key;
409 [ + - ]: 4356 : if (m_branch.size()) {
410 : : // If any script paths exist, they have been combined into the root m_branch[0]
411 : : // by now. Compute the control block for each of its tracked leaves, and put them in
412 : : // spd.scripts.
413 [ # # ]: 0 : for (const auto& leaf : m_branch[0]->leaves) {
414 : 0 : std::vector<unsigned char> control_block;
415 [ # # ]: 0 : control_block.resize(TAPROOT_CONTROL_BASE_SIZE + TAPROOT_CONTROL_NODE_SIZE * leaf.merkle_branch.size());
416 : 0 : control_block[0] = leaf.leaf_version | (m_parity ? 1 : 0);
417 [ # # ][ # # ]: 0 : std::copy(m_internal_key.begin(), m_internal_key.end(), control_block.begin() + 1);
[ # # ]
418 [ # # ]: 0 : if (leaf.merkle_branch.size()) {
419 [ # # ][ # # ]: 0 : std::copy(leaf.merkle_branch[0].begin(),
420 [ # # ]: 0 : leaf.merkle_branch[0].begin() + TAPROOT_CONTROL_NODE_SIZE * leaf.merkle_branch.size(),
421 : 0 : control_block.begin() + TAPROOT_CONTROL_BASE_SIZE);
422 : 0 : }
423 [ # # ][ # # ]: 0 : spd.scripts[{leaf.script, leaf.leaf_version}].insert(std::move(control_block));
[ # # ]
424 : 0 : }
425 : 0 : }
426 : 4356 : return spd;
427 [ + - ]: 4356 : }
428 : :
429 : 4356 : std::optional<std::vector<std::tuple<int, std::vector<unsigned char>, int>>> InferTaprootTree(const TaprootSpendData& spenddata, const XOnlyPubKey& output)
430 : : {
431 : : // Verify that the output matches the assumed Merkle root and internal key.
432 [ + - ]: 4356 : auto tweak = spenddata.internal_key.CreateTapTweak(spenddata.merkle_root.IsNull() ? nullptr : &spenddata.merkle_root);
433 [ + - ][ - + ]: 4356 : if (!tweak || tweak->first != output) return std::nullopt;
434 : : // If the Merkle root is 0, the tree is empty, and we're done.
435 : 4356 : std::vector<std::tuple<int, std::vector<unsigned char>, int>> ret;
436 [ + - ][ - + ]: 4356 : if (spenddata.merkle_root.IsNull()) return ret;
437 : :
438 : : /** Data structure to represent the nodes of the tree we're going to build. */
439 : 0 : struct TreeNode {
440 : : /** Hash of this node, if known; 0 otherwise. */
441 : : uint256 hash;
442 : : /** The left and right subtrees (note that their order is irrelevant). */
443 : : std::unique_ptr<TreeNode> sub[2];
444 : : /** If this is known to be a leaf node, a pointer to the (script, leaf_ver) pair.
445 : : * nullptr otherwise. */
446 : 0 : const std::pair<std::vector<unsigned char>, int>* leaf = nullptr;
447 : : /** Whether or not this node has been explored (is known to be a leaf, or known to have children). */
448 : 0 : bool explored = false;
449 : : /** Whether or not this node is an inner node (unknown until explored = true). */
450 : : bool inner;
451 : : /** Whether or not we have produced output for this subtree. */
452 : 0 : bool done = false;
453 : : };
454 : :
455 : : // Build tree from the provided branches.
456 [ # # ]: 0 : TreeNode root;
457 : 0 : root.hash = spenddata.merkle_root;
458 [ # # ]: 0 : for (const auto& [key, control_blocks] : spenddata.scripts) {
459 : 0 : const auto& [script, leaf_ver] = key;
460 [ # # ]: 0 : for (const auto& control : control_blocks) {
461 : : // Skip script records with nonsensical leaf version.
462 [ # # ][ # # ]: 0 : if (leaf_ver < 0 || leaf_ver >= 0x100 || leaf_ver & 1) continue;
[ # # ]
463 : : // Skip script records with invalid control block sizes.
464 [ # # ][ # # ]: 0 : if (control.size() < TAPROOT_CONTROL_BASE_SIZE || control.size() > TAPROOT_CONTROL_MAX_SIZE ||
[ # # ]
465 : 0 : ((control.size() - TAPROOT_CONTROL_BASE_SIZE) % TAPROOT_CONTROL_NODE_SIZE) != 0) continue;
466 : : // Skip script records that don't match the control block.
467 [ # # ][ # # ]: 0 : if ((control[0] & TAPROOT_LEAF_MASK) != leaf_ver) continue;
468 : : // Skip script records that don't match the provided Merkle root.
469 [ # # ][ # # ]: 0 : const uint256 leaf_hash = ComputeTapleafHash(leaf_ver, script);
[ # # ]
470 [ # # ][ # # ]: 0 : const uint256 merkle_root = ComputeTaprootMerkleRoot(control, leaf_hash);
471 [ # # ][ # # ]: 0 : if (merkle_root != spenddata.merkle_root) continue;
472 : :
473 : 0 : TreeNode* node = &root;
474 : 0 : size_t levels = (control.size() - TAPROOT_CONTROL_BASE_SIZE) / TAPROOT_CONTROL_NODE_SIZE;
475 [ # # ]: 0 : for (size_t depth = 0; depth < levels; ++depth) {
476 : : // Can't descend into a node which we already know is a leaf.
477 [ # # ][ # # ]: 0 : if (node->explored && !node->inner) return std::nullopt;
478 : :
479 : : // Extract partner hash from Merkle branch in control block.
480 [ # # ]: 0 : uint256 hash;
481 [ # # ]: 0 : std::copy(control.begin() + TAPROOT_CONTROL_BASE_SIZE + (levels - 1 - depth) * TAPROOT_CONTROL_NODE_SIZE,
482 : 0 : control.begin() + TAPROOT_CONTROL_BASE_SIZE + (levels - depth) * TAPROOT_CONTROL_NODE_SIZE,
483 [ # # ]: 0 : hash.begin());
484 : :
485 [ # # ]: 0 : if (node->sub[0]) {
486 : : // Descend into the existing left or right branch.
487 : 0 : bool desc = false;
488 [ # # ]: 0 : for (int i = 0; i < 2; ++i) {
489 [ # # ][ # # ]: 0 : if (node->sub[i]->hash == hash || (node->sub[i]->hash.IsNull() && node->sub[1-i]->hash != hash)) {
[ # # ][ # # ]
[ # # ][ # # ]
490 : 0 : node->sub[i]->hash = hash;
491 : 0 : node = &*node->sub[1-i];
492 : 0 : desc = true;
493 : 0 : break;
494 : : }
495 : 0 : }
496 [ # # ]: 0 : if (!desc) return std::nullopt; // This probably requires a hash collision to hit.
497 : 0 : } else {
498 : : // We're in an unexplored node. Create subtrees and descend.
499 : 0 : node->explored = true;
500 : 0 : node->inner = true;
501 [ # # ]: 0 : node->sub[0] = std::make_unique<TreeNode>();
502 [ # # ]: 0 : node->sub[1] = std::make_unique<TreeNode>();
503 : 0 : node->sub[1]->hash = hash;
504 : 0 : node = &*node->sub[0];
505 : : }
506 : 0 : }
507 : : // Cannot turn a known inner node into a leaf.
508 [ # # ]: 0 : if (node->sub[0]) return std::nullopt;
509 : 0 : node->explored = true;
510 : 0 : node->inner = false;
511 : 0 : node->leaf = &key;
512 : 0 : node->hash = leaf_hash;
513 : : }
514 : : }
515 : :
516 : : // Recursive processing to turn the tree into flattened output. Use an explicit stack here to avoid
517 : : // overflowing the call stack (the tree may be 128 levels deep).
518 [ # # ]: 0 : std::vector<TreeNode*> stack{&root};
519 [ # # ]: 0 : while (!stack.empty()) {
520 : 0 : TreeNode& node = *stack.back();
521 [ # # ]: 0 : if (!node.explored) {
522 : : // Unexplored node, which means the tree is incomplete.
523 : 0 : return std::nullopt;
524 [ # # ]: 0 : } else if (!node.inner) {
525 : : // Leaf node; produce output.
526 [ # # ]: 0 : ret.emplace_back(stack.size() - 1, node.leaf->first, node.leaf->second);
527 : 0 : node.done = true;
528 : 0 : stack.pop_back();
529 [ # # ][ # # ]: 0 : } else if (node.sub[0]->done && !node.sub[1]->done && !node.sub[1]->explored && !node.sub[1]->hash.IsNull() &&
[ # # ][ # # ]
[ # # ][ # # ]
530 [ # # ][ # # ]: 0 : ComputeTapbranchHash(node.sub[1]->hash, node.sub[1]->hash) == node.hash) {
[ # # ][ # # ]
531 : : // Whenever there are nodes with two identical subtrees under it, we run into a problem:
532 : : // the control blocks for the leaves underneath those will be identical as well, and thus
533 : : // they will all be matched to the same path in the tree. The result is that at the location
534 : : // where the duplicate occurred, the left child will contain a normal tree that can be explored
535 : : // and processed, but the right one will remain unexplored.
536 : : //
537 : : // This situation can be detected, by encountering an inner node with unexplored right subtree
538 : : // with known hash, and H_TapBranch(hash, hash) is equal to the parent node (this node)'s hash.
539 : : //
540 : : // To deal with this, simply process the left tree a second time (set its done flag to false;
541 : : // noting that the done flag of its children have already been set to false after processing
542 : : // those). To avoid ending up in an infinite loop, set the done flag of the right (unexplored)
543 : : // subtree to true.
544 : 0 : node.sub[0]->done = false;
545 : 0 : node.sub[1]->done = true;
546 [ # # ][ # # ]: 0 : } else if (node.sub[0]->done && node.sub[1]->done) {
547 : : // An internal node which we're finished with.
548 : 0 : node.sub[0]->done = false;
549 : 0 : node.sub[1]->done = false;
550 : 0 : node.done = true;
551 : 0 : stack.pop_back();
552 [ # # ]: 0 : } else if (!node.sub[0]->done) {
553 : : // An internal node whose left branch hasn't been processed yet. Do so first.
554 [ # # ]: 0 : stack.push_back(&*node.sub[0]);
555 [ # # ]: 0 : } else if (!node.sub[1]->done) {
556 : : // An internal node whose right branch hasn't been processed yet. Do so first.
557 [ # # ]: 0 : stack.push_back(&*node.sub[1]);
558 : 0 : }
559 : : }
560 : :
561 : 0 : return ret;
562 : 4356 : }
563 : :
564 : 0 : std::vector<std::tuple<uint8_t, uint8_t, std::vector<unsigned char>>> TaprootBuilder::GetTreeTuples() const
565 : : {
566 [ # # ]: 0 : assert(IsComplete());
567 : 0 : std::vector<std::tuple<uint8_t, uint8_t, std::vector<unsigned char>>> tuples;
568 [ # # ]: 0 : if (m_branch.size()) {
569 : 0 : const auto& leaves = m_branch[0]->leaves;
570 [ # # ]: 0 : for (const auto& leaf : leaves) {
571 [ # # ]: 0 : assert(leaf.merkle_branch.size() <= TAPROOT_CONTROL_MAX_NODE_COUNT);
572 : 0 : uint8_t depth = (uint8_t)leaf.merkle_branch.size();
573 : 0 : uint8_t leaf_ver = (uint8_t)leaf.leaf_version;
574 [ # # ]: 0 : tuples.emplace_back(depth, leaf_ver, leaf.script);
575 : : }
576 : 0 : }
577 : 0 : return tuples;
578 [ # # ]: 0 : }
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