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1 : : // Copyright (c) 2020-2021 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 : : #include <crypto/common.h>
6 : : #include <crypto/sha256.h>
7 : : #include <crypto/siphash.h>
8 : : #include <primitives/transaction.h>
9 : : #include <test/fuzz/fuzz.h>
10 : : #include <txrequest.h>
11 : :
12 : : #include <bitset>
13 : : #include <cstdint>
14 : : #include <queue>
15 : : #include <vector>
16 : :
17 [ + - ]: 2 : namespace {
18 [ + - ]: 2 :
19 : : constexpr int MAX_TXHASHES = 16;
20 : : constexpr int MAX_PEERS = 16;
21 : :
22 : : //! Randomly generated GenTxids used in this test (length is MAX_TXHASHES).
23 : : uint256 TXHASHES[MAX_TXHASHES];
24 : :
25 : 2 : //! Precomputed random durations (positive and negative, each ~exponentially distributed).
26 : : std::chrono::microseconds DELAYS[256];
27 : :
28 : : struct Initializer
29 : : {
30 : 2 : Initializer()
31 : : {
32 [ + + ]: 34 : for (uint8_t txhash = 0; txhash < MAX_TXHASHES; txhash += 1) {
33 : 32 : CSHA256().Write(&txhash, 1).Finalize(TXHASHES[txhash].begin());
34 : 32 : }
35 : 2 : int i = 0;
36 : : // DELAYS[N] for N=0..15 is just N microseconds.
37 [ + + ]: 34 : for (; i < 16; ++i) {
38 : 32 : DELAYS[i] = std::chrono::microseconds{i};
39 : 32 : }
40 : : // DELAYS[N] for N=16..127 has randomly-looking but roughly exponentially increasing values up to
41 : : // 198.416453 seconds.
42 [ + + ]: 226 : for (; i < 128; ++i) {
43 : 224 : int diff_bits = ((i - 10) * 2) / 9;
44 : 224 : uint64_t diff = 1 + (CSipHasher(0, 0).Write(i).Finalize() >> (64 - diff_bits));
45 : 224 : DELAYS[i] = DELAYS[i - 1] + std::chrono::microseconds{diff};
46 : 224 : }
47 : : // DELAYS[N] for N=128..255 are negative delays with the same magnitude as N=0..127.
48 [ + + ]: 258 : for (; i < 256; ++i) {
49 : 256 : DELAYS[i] = -DELAYS[255 - i];
50 : 256 : }
51 : 2 : }
52 : 2 : } g_initializer;
53 : :
54 : : /** Tester class for TxRequestTracker
55 : : *
56 : : * It includes a naive reimplementation of its behavior, for a limited set
57 : : * of MAX_TXHASHES distinct txids, and MAX_PEERS peer identifiers.
58 : : *
59 : : * All of the public member functions perform the same operation on
60 : : * an actual TxRequestTracker and on the state of the reimplementation.
61 : : * The output of GetRequestable is compared with the expected value
62 : : * as well.
63 : : *
64 : : * Check() calls the TxRequestTracker's sanity check, plus compares the
65 : : * output of the constant accessors (Size(), CountLoad(), CountTracked())
66 : : * with expected values.
67 : : */
68 : 0 : class Tester
69 : : {
70 : : //! TxRequestTracker object being tested.
71 : : TxRequestTracker m_tracker;
72 : :
73 : : //! States for txid/peer combinations in the naive data structure.
74 : : enum class State {
75 : : NOTHING, //!< Absence of this txid/peer combination
76 : :
77 : : // Note that this implementation does not distinguish between DELAYED/READY/BEST variants of CANDIDATE.
78 : : CANDIDATE,
79 : : REQUESTED,
80 : : COMPLETED,
81 : : };
82 : :
83 [ + - ]: 2 : //! Sequence numbers, incremented whenever a new CANDIDATE is added.
84 : 0 : uint64_t m_current_sequence{0};
85 : :
86 : : //! List of future 'events' (all inserted reqtimes/exptimes). This is used to implement AdvanceToEvent.
87 : : std::priority_queue<std::chrono::microseconds, std::vector<std::chrono::microseconds>,
88 : : std::greater<std::chrono::microseconds>> m_events;
89 : :
90 : : //! Information about a txhash/peer combination.
91 : 0 : struct Announcement
92 : : {
93 : : std::chrono::microseconds m_time;
94 : : uint64_t m_sequence;
95 : 0 : State m_state{State::NOTHING};
96 : : bool m_preferred;
97 : : bool m_is_wtxid;
98 : : uint64_t m_priority; //!< Precomputed priority.
99 : : };
100 : :
101 : : //! Information about all txhash/peer combination.
102 : : Announcement m_announcements[MAX_TXHASHES][MAX_PEERS];
103 : :
104 : : //! The current time; can move forward and backward.
105 [ # # ]: 0 : std::chrono::microseconds m_now{244466666};
106 : :
107 : : //! Delete txhashes whose only announcements are COMPLETED.
108 : 0 : void Cleanup(int txhash)
109 : : {
110 : 0 : bool all_nothing = true;
111 [ # # ]: 0 : for (int peer = 0; peer < MAX_PEERS; ++peer) {
112 : 0 : const Announcement& ann = m_announcements[txhash][peer];
113 [ # # ]: 0 : if (ann.m_state != State::NOTHING) {
114 [ # # ]: 0 : if (ann.m_state != State::COMPLETED) return;
115 : 0 : all_nothing = false;
116 : 0 : }
117 : 0 : }
118 [ # # ]: 0 : if (all_nothing) return;
119 [ # # ]: 0 : for (int peer = 0; peer < MAX_PEERS; ++peer) {
120 : 0 : m_announcements[txhash][peer].m_state = State::NOTHING;
121 : 0 : }
122 : 0 : }
123 : :
124 : : //! Find the current best peer to request from for a txhash (or -1 if none).
125 : 0 : int GetSelected(int txhash) const
126 : : {
127 : 0 : int ret = -1;
128 : 0 : uint64_t ret_priority = 0;
129 [ # # ]: 0 : for (int peer = 0; peer < MAX_PEERS; ++peer) {
130 : 0 : const Announcement& ann = m_announcements[txhash][peer];
131 : : // Return -1 if there already is a (non-expired) in-flight request.
132 [ # # ]: 0 : if (ann.m_state == State::REQUESTED) return -1;
133 : : // If it's a viable candidate, see if it has lower priority than the best one so far.
134 [ # # ][ # # ]: 0 : if (ann.m_state == State::CANDIDATE && ann.m_time <= m_now) {
135 [ # # ][ # # ]: 0 : if (ret == -1 || ann.m_priority > ret_priority) {
136 : 0 : std::tie(ret, ret_priority) = std::tie(peer, ann.m_priority);
137 : 0 : }
138 : 0 : }
139 : 0 : }
140 : 0 : return ret;
141 : 0 : }
142 : :
143 : : public:
144 [ # # ][ # # ]: 0 : Tester() : m_tracker(true) {}
145 : :
146 : 0 : std::chrono::microseconds Now() const { return m_now; }
147 : :
148 : 0 : void AdvanceTime(std::chrono::microseconds offset)
149 : : {
150 : 0 : m_now += offset;
151 [ # # ][ # # ]: 0 : while (!m_events.empty() && m_events.top() <= m_now) m_events.pop();
152 : 0 : }
153 : :
154 : 0 : void AdvanceToEvent()
155 : : {
156 [ # # ][ # # ]: 0 : while (!m_events.empty() && m_events.top() <= m_now) m_events.pop();
157 [ # # ]: 0 : if (!m_events.empty()) {
158 : 0 : m_now = m_events.top();
159 : 0 : m_events.pop();
160 : 0 : }
161 : 0 : }
162 : :
163 : 0 : void DisconnectedPeer(int peer)
164 : : {
165 : : // Apply to naive structure: all announcements for that peer are wiped.
166 [ # # ]: 0 : for (int txhash = 0; txhash < MAX_TXHASHES; ++txhash) {
167 [ # # ]: 0 : if (m_announcements[txhash][peer].m_state != State::NOTHING) {
168 : 0 : m_announcements[txhash][peer].m_state = State::NOTHING;
169 : 0 : Cleanup(txhash);
170 : 0 : }
171 : 0 : }
172 : :
173 : : // Call TxRequestTracker's implementation.
174 : 0 : m_tracker.DisconnectedPeer(peer);
175 : 0 : }
176 : :
177 : 0 : void ForgetTxHash(int txhash)
178 : : {
179 : : // Apply to naive structure: all announcements for that txhash are wiped.
180 [ # # ]: 0 : for (int peer = 0; peer < MAX_PEERS; ++peer) {
181 : 0 : m_announcements[txhash][peer].m_state = State::NOTHING;
182 : 0 : }
183 : 0 : Cleanup(txhash);
184 : :
185 : : // Call TxRequestTracker's implementation.
186 : 0 : m_tracker.ForgetTxHash(TXHASHES[txhash]);
187 : 0 : }
188 : :
189 : 0 : void ReceivedInv(int peer, int txhash, bool is_wtxid, bool preferred, std::chrono::microseconds reqtime)
190 : : {
191 : : // Apply to naive structure: if no announcement for txidnum/peer combination
192 : : // already, create a new CANDIDATE; otherwise do nothing.
193 : 0 : Announcement& ann = m_announcements[txhash][peer];
194 [ # # ]: 0 : if (ann.m_state == State::NOTHING) {
195 : 0 : ann.m_preferred = preferred;
196 : 0 : ann.m_state = State::CANDIDATE;
197 : 0 : ann.m_time = reqtime;
198 : 0 : ann.m_is_wtxid = is_wtxid;
199 : 0 : ann.m_sequence = m_current_sequence++;
200 : 0 : ann.m_priority = m_tracker.ComputePriority(TXHASHES[txhash], peer, ann.m_preferred);
201 : :
202 : : // Add event so that AdvanceToEvent can quickly jump to the point where its reqtime passes.
203 [ # # ]: 0 : if (reqtime > m_now) m_events.push(reqtime);
204 : 0 : }
205 : :
206 : : // Call TxRequestTracker's implementation.
207 [ # # ]: 0 : m_tracker.ReceivedInv(peer, is_wtxid ? GenTxid::Wtxid(TXHASHES[txhash]) : GenTxid::Txid(TXHASHES[txhash]), preferred, reqtime);
208 : 0 : }
209 : :
210 : 0 : void RequestedTx(int peer, int txhash, std::chrono::microseconds exptime)
211 : : {
212 : : // Apply to naive structure: if a CANDIDATE announcement exists for peer/txhash,
213 : : // convert it to REQUESTED, and change any existing REQUESTED announcement for the same txhash to COMPLETED.
214 [ # # ]: 0 : if (m_announcements[txhash][peer].m_state == State::CANDIDATE) {
215 [ # # ]: 0 : for (int peer2 = 0; peer2 < MAX_PEERS; ++peer2) {
216 [ # # ]: 0 : if (m_announcements[txhash][peer2].m_state == State::REQUESTED) {
217 : 0 : m_announcements[txhash][peer2].m_state = State::COMPLETED;
218 : 0 : }
219 : 0 : }
220 : 0 : m_announcements[txhash][peer].m_state = State::REQUESTED;
221 : 0 : m_announcements[txhash][peer].m_time = exptime;
222 : 0 : }
223 : :
224 : : // Add event so that AdvanceToEvent can quickly jump to the point where its exptime passes.
225 [ # # ]: 0 : if (exptime > m_now) m_events.push(exptime);
226 : :
227 : : // Call TxRequestTracker's implementation.
228 : 0 : m_tracker.RequestedTx(peer, TXHASHES[txhash], exptime);
229 : 0 : }
230 : :
231 : 0 : void ReceivedResponse(int peer, int txhash)
232 : : {
233 : : // Apply to naive structure: convert anything to COMPLETED.
234 [ # # ]: 0 : if (m_announcements[txhash][peer].m_state != State::NOTHING) {
235 : 0 : m_announcements[txhash][peer].m_state = State::COMPLETED;
236 : 0 : Cleanup(txhash);
237 : 0 : }
238 : :
239 : : // Call TxRequestTracker's implementation.
240 : 0 : m_tracker.ReceivedResponse(peer, TXHASHES[txhash]);
241 : 0 : }
242 : :
243 : 0 : void GetRequestable(int peer)
244 : : {
245 : : // Implement using naive structure:
246 : :
247 : : //! list of (sequence number, txhash, is_wtxid) tuples.
248 : 0 : std::vector<std::tuple<uint64_t, int, bool>> result;
249 : 0 : std::vector<std::pair<NodeId, GenTxid>> expected_expired;
250 [ # # ]: 0 : for (int txhash = 0; txhash < MAX_TXHASHES; ++txhash) {
251 : : // Mark any expired REQUESTED announcements as COMPLETED.
252 [ # # ]: 0 : for (int peer2 = 0; peer2 < MAX_PEERS; ++peer2) {
253 : 0 : Announcement& ann2 = m_announcements[txhash][peer2];
254 [ # # ][ # # ]: 0 : if (ann2.m_state == State::REQUESTED && ann2.m_time <= m_now) {
[ # # ]
255 [ # # ][ # # ]: 0 : expected_expired.emplace_back(peer2, ann2.m_is_wtxid ? GenTxid::Wtxid(TXHASHES[txhash]) : GenTxid::Txid(TXHASHES[txhash]));
[ # # ][ # # ]
256 : 0 : ann2.m_state = State::COMPLETED;
257 : 0 : break;
258 : : }
259 : 0 : }
260 : : // And delete txids with only COMPLETED announcements left.
261 [ # # ]: 0 : Cleanup(txhash);
262 : : // CANDIDATEs for which this announcement has the highest priority get returned.
263 : 0 : const Announcement& ann = m_announcements[txhash][peer];
264 [ # # ][ # # ]: 0 : if (ann.m_state == State::CANDIDATE && GetSelected(txhash) == peer) {
[ # # ]
265 [ # # ]: 0 : result.emplace_back(ann.m_sequence, txhash, ann.m_is_wtxid);
266 : 0 : }
267 : 0 : }
268 : : // Sort the results by sequence number.
269 [ # # ]: 0 : std::sort(result.begin(), result.end());
270 [ # # ]: 0 : std::sort(expected_expired.begin(), expected_expired.end());
271 : :
272 : : // Compare with TxRequestTracker's implementation.
273 : 0 : std::vector<std::pair<NodeId, GenTxid>> expired;
274 [ # # ]: 0 : const auto actual = m_tracker.GetRequestable(peer, m_now, &expired);
275 [ # # ]: 0 : std::sort(expired.begin(), expired.end());
276 [ # # ][ # # ]: 0 : assert(expired == expected_expired);
277 : :
278 [ # # ]: 0 : m_tracker.PostGetRequestableSanityCheck(m_now);
279 [ # # ]: 0 : assert(result.size() == actual.size());
280 [ # # ]: 0 : for (size_t pos = 0; pos < actual.size(); ++pos) {
281 [ # # ][ # # ]: 0 : assert(TXHASHES[std::get<1>(result[pos])] == actual[pos].GetHash());
[ # # ]
282 [ # # ][ # # ]: 0 : assert(std::get<2>(result[pos]) == actual[pos].IsWtxid());
283 : 0 : }
284 : 0 : }
285 : :
286 : 0 : void Check()
287 : : {
288 : : // Compare CountTracked and CountLoad with naive structure.
289 : 0 : size_t total = 0;
290 [ # # ]: 0 : for (int peer = 0; peer < MAX_PEERS; ++peer) {
291 : 0 : size_t tracked = 0;
292 : 0 : size_t inflight = 0;
293 : 0 : size_t candidates = 0;
294 [ # # ]: 0 : for (int txhash = 0; txhash < MAX_TXHASHES; ++txhash) {
295 : 0 : tracked += m_announcements[txhash][peer].m_state != State::NOTHING;
296 : 0 : inflight += m_announcements[txhash][peer].m_state == State::REQUESTED;
297 : 0 : candidates += m_announcements[txhash][peer].m_state == State::CANDIDATE;
298 : 0 : }
299 [ # # ]: 0 : assert(m_tracker.Count(peer) == tracked);
300 [ # # ]: 0 : assert(m_tracker.CountInFlight(peer) == inflight);
301 [ # # ]: 0 : assert(m_tracker.CountCandidates(peer) == candidates);
302 : 0 : total += tracked;
303 : 0 : }
304 : : // Compare Size.
305 [ # # ]: 0 : assert(m_tracker.Size() == total);
306 : :
307 : : // Invoke internal consistency check of TxRequestTracker object.
308 : 0 : m_tracker.SanityCheck();
309 : 0 : }
310 : : };
311 : : } // namespace
312 : :
313 [ + - ][ + - ]: 6 : FUZZ_TARGET(txrequest)
314 : : {
315 : : // Tester object (which encapsulates a TxRequestTracker).
316 : 0 : Tester tester;
317 : :
318 : : // Decode the input as a sequence of instructions with parameters
319 : 0 : auto it = buffer.begin();
320 [ # # ]: 0 : while (it != buffer.end()) {
321 : 0 : int cmd = *(it++) % 11;
322 : : int peer, txidnum, delaynum;
323 [ # # # # : 0 : switch (cmd) {
# # # # #
# ]
324 : : case 0: // Make time jump to the next event (m_time of CANDIDATE or REQUESTED)
325 [ # # ]: 0 : tester.AdvanceToEvent();
326 : 0 : break;
327 : : case 1: // Change time
328 [ # # ]: 0 : delaynum = it == buffer.end() ? 0 : *(it++);
329 [ # # ]: 0 : tester.AdvanceTime(DELAYS[delaynum]);
330 : 0 : break;
331 : : case 2: // Query for requestable txs
332 [ # # ]: 0 : peer = it == buffer.end() ? 0 : *(it++) % MAX_PEERS;
333 [ # # ]: 0 : tester.GetRequestable(peer);
334 : 0 : break;
335 : : case 3: // Peer went offline
336 [ # # ]: 0 : peer = it == buffer.end() ? 0 : *(it++) % MAX_PEERS;
337 [ # # ]: 0 : tester.DisconnectedPeer(peer);
338 : 0 : break;
339 : : case 4: // No longer need tx
340 [ # # ]: 0 : txidnum = it == buffer.end() ? 0 : *(it++);
341 [ # # ]: 0 : tester.ForgetTxHash(txidnum % MAX_TXHASHES);
342 : 0 : break;
343 : : case 5: // Received immediate preferred inv
344 : : case 6: // Same, but non-preferred.
345 [ # # ]: 0 : peer = it == buffer.end() ? 0 : *(it++) % MAX_PEERS;
346 [ # # ]: 0 : txidnum = it == buffer.end() ? 0 : *(it++);
347 [ # # ][ # # ]: 0 : tester.ReceivedInv(peer, txidnum % MAX_TXHASHES, (txidnum / MAX_TXHASHES) & 1, cmd & 1,
348 : 0 : std::chrono::microseconds::min());
349 : 0 : break;
350 : : case 7: // Received delayed preferred inv
351 : : case 8: // Same, but non-preferred.
352 [ # # ]: 0 : peer = it == buffer.end() ? 0 : *(it++) % MAX_PEERS;
353 [ # # ]: 0 : txidnum = it == buffer.end() ? 0 : *(it++);
354 [ # # ]: 0 : delaynum = it == buffer.end() ? 0 : *(it++);
355 [ # # ]: 0 : tester.ReceivedInv(peer, txidnum % MAX_TXHASHES, (txidnum / MAX_TXHASHES) & 1, cmd & 1,
356 [ # # ][ # # ]: 0 : tester.Now() + DELAYS[delaynum]);
357 : 0 : break;
358 : : case 9: // Requested tx from peer
359 [ # # ]: 0 : peer = it == buffer.end() ? 0 : *(it++) % MAX_PEERS;
360 [ # # ]: 0 : txidnum = it == buffer.end() ? 0 : *(it++);
361 [ # # ]: 0 : delaynum = it == buffer.end() ? 0 : *(it++);
362 [ # # ][ # # ]: 0 : tester.RequestedTx(peer, txidnum % MAX_TXHASHES, tester.Now() + DELAYS[delaynum]);
[ # # ]
363 : 0 : break;
364 : : case 10: // Received response
365 [ # # ]: 0 : peer = it == buffer.end() ? 0 : *(it++) % MAX_PEERS;
366 [ # # ]: 0 : txidnum = it == buffer.end() ? 0 : *(it++);
367 [ # # ]: 0 : tester.ReceivedResponse(peer, txidnum % MAX_TXHASHES);
368 : 0 : break;
369 : : default:
370 : 0 : assert(false);
371 : : }
372 : : }
373 [ # # ]: 0 : tester.Check();
374 : 0 : }
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