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1 : : // Copyright (c) 2019-2022 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 <chainparams.h>
6 : : #include <hash.h>
7 : : #include <net.h>
8 : : #include <netmessagemaker.h>
9 : : #include <protocol.h>
10 : : #include <test/fuzz/FuzzedDataProvider.h>
11 : : #include <test/fuzz/fuzz.h>
12 : : #include <test/fuzz/util.h>
13 : : #include <util/chaintype.h>
14 : :
15 : : #include <algorithm>
16 : : #include <cassert>
17 : : #include <cstdint>
18 : : #include <limits>
19 : : #include <optional>
20 : : #include <vector>
21 : :
22 : : namespace {
23 : :
24 : : auto g_all_messages = ALL_NET_MESSAGE_TYPES;
25 : :
26 : 4 : void initialize_p2p_transport_serialization()
27 : : {
28 [ + - + - : 4 : static ECC_Context ecc_context{};
+ - ]
29 : 4 : SelectParams(ChainType::REGTEST);
30 : 4 : std::sort(g_all_messages.begin(), g_all_messages.end());
31 : 4 : }
32 : :
33 : : } // namespace
34 : :
35 [ + - ]: 770 : FUZZ_TARGET(p2p_transport_serialization, .init = initialize_p2p_transport_serialization)
36 : : {
37 : : // Construct transports for both sides, with dummy NodeIds.
38 : 358 : V1Transport recv_transport{NodeId{0}};
39 : 358 : V1Transport send_transport{NodeId{1}};
40 : :
41 : 358 : FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
42 : :
43 : 358 : auto checksum_assist = fuzzed_data_provider.ConsumeBool();
44 : 358 : auto magic_bytes_assist = fuzzed_data_provider.ConsumeBool();
45 : 358 : std::vector<uint8_t> mutable_msg_bytes;
46 : :
47 : 358 : auto header_bytes_remaining = CMessageHeader::HEADER_SIZE;
48 [ + + ]: 358 : if (magic_bytes_assist) {
49 [ + - ]: 286 : auto msg_start = Params().MessageStart();
50 [ + + ]: 1430 : for (size_t i = 0; i < CMessageHeader::MESSAGE_SIZE_SIZE; ++i) {
51 [ + - ]: 1144 : mutable_msg_bytes.push_back(msg_start[i]);
52 : : }
53 : : header_bytes_remaining -= CMessageHeader::MESSAGE_SIZE_SIZE;
54 : : }
55 : :
56 [ + + ]: 358 : if (checksum_assist) {
57 : 171 : header_bytes_remaining -= CMessageHeader::CHECKSUM_SIZE;
58 : : }
59 : :
60 [ + - ]: 358 : auto header_random_bytes = fuzzed_data_provider.ConsumeBytes<uint8_t>(header_bytes_remaining);
61 [ + - ]: 358 : mutable_msg_bytes.insert(mutable_msg_bytes.end(), header_random_bytes.begin(), header_random_bytes.end());
62 [ + - ]: 358 : auto payload_bytes = fuzzed_data_provider.ConsumeRemainingBytes<uint8_t>();
63 : :
64 [ + + + + ]: 358 : if (checksum_assist && mutable_msg_bytes.size() == CMessageHeader::CHECKSUM_OFFSET) {
65 [ + - ]: 169 : CHash256 hasher;
66 : 169 : unsigned char hsh[32];
67 [ + - ]: 169 : hasher.Write(payload_bytes);
68 [ + - ]: 169 : hasher.Finalize(hsh);
69 [ + + ]: 845 : for (size_t i = 0; i < CMessageHeader::CHECKSUM_SIZE; ++i) {
70 [ + - ]: 676 : mutable_msg_bytes.push_back(hsh[i]);
71 : : }
72 : : }
73 : :
74 [ + - ]: 358 : mutable_msg_bytes.insert(mutable_msg_bytes.end(), payload_bytes.begin(), payload_bytes.end());
75 : 358 : Span<const uint8_t> msg_bytes{mutable_msg_bytes};
76 [ + + ]: 85195 : while (msg_bytes.size() > 0) {
77 [ + - + + ]: 84577 : if (!recv_transport.ReceivedBytes(msg_bytes)) {
78 : : break;
79 : : }
80 [ + - + + ]: 84479 : if (recv_transport.ReceivedMessageComplete()) {
81 : 50762 : const std::chrono::microseconds m_time{std::numeric_limits<int64_t>::max()};
82 : 50762 : bool reject_message{false};
83 [ + - ]: 50762 : CNetMessage msg = recv_transport.GetReceivedMessage(m_time, reject_message);
84 [ - + ]: 50762 : assert(msg.m_type.size() <= CMessageHeader::MESSAGE_TYPE_SIZE);
85 [ - + ]: 50762 : assert(msg.m_raw_message_size <= mutable_msg_bytes.size());
86 [ - + ]: 50762 : assert(msg.m_raw_message_size == CMessageHeader::HEADER_SIZE + msg.m_message_size);
87 [ - + ]: 50762 : assert(msg.m_time == m_time);
88 : :
89 : 50762 : std::vector<unsigned char> header;
90 [ + - + - ]: 50762 : auto msg2 = NetMsg::Make(msg.m_type, Span{msg.m_recv});
91 : 50762 : bool queued = send_transport.SetMessageToSend(msg2);
92 [ - + ]: 50762 : assert(queued);
93 : 50762 : std::optional<bool> known_more;
94 : 219316 : while (true) {
95 [ + + ]: 135039 : const auto& [to_send, more, _msg_type] = send_transport.GetBytesToSend(false);
96 [ + + - + ]: 135039 : if (known_more) assert(!to_send.empty() == *known_more);
97 [ + + ]: 135039 : if (to_send.empty()) break;
98 : 84277 : send_transport.MarkBytesSent(to_send.size());
99 : 84277 : known_more = more;
100 : 84277 : }
101 : 101524 : }
102 : : }
103 : 358 : }
104 : :
105 : : namespace {
106 : :
107 : : template<RandomNumberGenerator R>
108 : 1472 : void SimulationTest(Transport& initiator, Transport& responder, R& rng, FuzzedDataProvider& provider)
109 : : {
110 : : // Simulation test with two Transport objects, which send messages to each other, with
111 : : // sending and receiving fragmented into multiple pieces that may be interleaved. It primarily
112 : : // verifies that the sending and receiving side are compatible with each other, plus a few
113 : : // sanity checks. It does not attempt to introduce errors in the communicated data.
114 : :
115 : : // Put the transports in an array for by-index access.
116 : 1472 : const std::array<Transport*, 2> transports = {&initiator, &responder};
117 : :
118 : : // Two vectors representing in-flight bytes. inflight[i] is from transport[i] to transport[!i].
119 : 1472 : std::array<std::vector<uint8_t>, 2> in_flight;
120 : :
121 : : // Two queues with expected messages. expected[i] is expected to arrive in transport[!i].
122 [ + - ]: 1472 : std::array<std::deque<CSerializedNetMsg>, 2> expected;
123 : :
124 : : // Vectors with bytes last returned by GetBytesToSend() on transport[i].
125 : 1472 : std::array<std::vector<uint8_t>, 2> to_send;
126 : :
127 : : // Last returned 'more' values (if still relevant) by transport[i]->GetBytesToSend(), for
128 : : // both have_next_message false and true.
129 : 1472 : std::array<std::optional<bool>, 2> last_more, last_more_next;
130 : :
131 : : // Whether more bytes to be sent are expected on transport[i], before and after
132 : : // SetMessageToSend().
133 : 1472 : std::array<std::optional<bool>, 2> expect_more, expect_more_next;
134 : :
135 : : // Function to consume a message type.
136 : 48355 : auto msg_type_fn = [&]() {
137 : 46883 : uint8_t v = provider.ConsumeIntegral<uint8_t>();
138 [ + + ]: 46883 : if (v == 0xFF) {
139 : : // If v is 0xFF, construct a valid (but possibly unknown) message type from the fuzz
140 : : // data.
141 : 6983 : std::string ret;
142 : 31055 : while (ret.size() < CMessageHeader::MESSAGE_TYPE_SIZE) {
143 : 29984 : char c = provider.ConsumeIntegral<char>();
144 : : // Match the allowed characters in CMessageHeader::IsMessageTypeValid(). Any other
145 : : // character is interpreted as end.
146 [ + + ]: 29984 : if (c < ' ' || c > 0x7E) break;
147 [ + - + + ]: 55127 : ret += c;
148 : : }
149 : : return ret;
150 : 0 : } else {
151 : : // Otherwise, use it as index into the list of known messages.
152 : 39900 : return g_all_messages[v % g_all_messages.size()];
153 : : }
154 : : };
155 : :
156 : : // Function to construct a CSerializedNetMsg to send.
157 [ + + ]: 49827 : auto make_msg_fn = [&](bool first) {
158 : 49827 : CSerializedNetMsg msg;
159 [ + + ]: 49827 : if (first) {
160 : : // Always send a "version" message as first one.
161 [ + - ]: 2944 : msg.m_type = "version";
162 : : } else {
163 [ + - ]: 46883 : msg.m_type = msg_type_fn();
164 : : }
165 : : // Determine size of message to send (limited to 75 kB for performance reasons).
166 : 49827 : size_t size = provider.ConsumeIntegralInRange<uint32_t>(0, 75000);
167 : : // Get payload of message from RNG.
168 : 49827 : msg.data = rng.randbytes(size);
169 : : // Return.
170 : 49827 : return msg;
171 : 0 : };
172 : :
173 : : // The next message to be sent (initially version messages, but will be replaced once sent).
174 [ + - + - : 1472 : std::array<CSerializedNetMsg, 2> next_msg = {
- - ]
175 : : make_msg_fn(/*first=*/true),
176 : : make_msg_fn(/*first=*/true)
177 : : };
178 : :
179 : : // Wrapper around transport[i]->GetBytesToSend() that performs sanity checks.
180 : 790926 : auto bytes_to_send_fn = [&](int side) -> Transport::BytesToSend {
181 : : // Invoke GetBytesToSend twice (for have_next_message = {false, true}). This function does
182 : : // not modify state (it's const), and only the "more" return value should differ between
183 : : // the calls.
184 : 789454 : const auto& [bytes, more_nonext, msg_type] = transports[side]->GetBytesToSend(false);
185 [ + + ]: 789454 : const auto& [bytes_next, more_next, msg_type_next] = transports[side]->GetBytesToSend(true);
186 : : // Compare with expected more.
187 [ + + ]: 789454 : if (expect_more[side].has_value()) assert(!bytes.empty() == *expect_more[side]);
188 : : // Verify consistency between the two results.
189 [ - + ]: 789454 : assert(std::ranges::equal(bytes, bytes_next));
190 [ - + ]: 789454 : assert(msg_type == msg_type_next);
191 [ + + - + ]: 789454 : if (more_nonext) assert(more_next);
192 : : // Compare with previously reported output.
193 [ - + ]: 789454 : assert(to_send[side].size() <= bytes.size());
194 [ - + ]: 789454 : assert(std::ranges::equal(to_send[side], Span{bytes}.first(to_send[side].size())));
195 : 789454 : to_send[side].resize(bytes.size());
196 : 789454 : std::copy(bytes.begin(), bytes.end(), to_send[side].begin());
197 : : // Remember 'more' results.
198 : 789454 : last_more[side] = {more_nonext};
199 : 789454 : last_more_next[side] = {more_next};
200 : : // Return.
201 : 789454 : return {bytes, more_nonext, msg_type};
202 : : };
203 : :
204 : : // Function to make side send a new message.
205 : 233921 : auto new_msg_fn = [&](int side) {
206 : : // Don't do anything if there are too many unreceived messages already.
207 [ + + ]: 232449 : if (expected[side].size() >= 16) return;
208 : : // Try to send (a copy of) the message in next_msg[side].
209 : 229690 : CSerializedNetMsg msg = next_msg[side].Copy();
210 : 229690 : bool queued = transports[side]->SetMessageToSend(msg);
211 : : // Update expected more data.
212 [ + + ]: 229690 : expect_more[side] = expect_more_next[side];
213 [ + + ]: 229690 : expect_more_next[side] = std::nullopt;
214 : : // Verify consistency of GetBytesToSend after SetMessageToSend
215 [ + - ]: 229690 : bytes_to_send_fn(/*side=*/side);
216 [ + + ]: 229690 : if (queued) {
217 : : // Remember that this message is now expected by the receiver.
218 [ + - ]: 46883 : expected[side].emplace_back(std::move(next_msg[side]));
219 : : // Construct a new next message to send.
220 [ + - ]: 93766 : next_msg[side] = make_msg_fn(/*first=*/false);
221 : : }
222 : 229690 : };
223 : :
224 : : // Function to make side send out bytes (if any).
225 : 279858 : auto send_fn = [&](int side, bool everything = false) {
226 [ + + ]: 278386 : const auto& [bytes, more, msg_type] = bytes_to_send_fn(/*side=*/side);
227 : : // Don't do anything if no bytes to send.
228 [ + + ]: 278386 : if (bytes.empty()) return false;
229 [ + + ]: 203516 : size_t send_now = everything ? bytes.size() : provider.ConsumeIntegralInRange<size_t>(0, bytes.size());
230 [ + + ]: 203516 : if (send_now == 0) return false;
231 : : // Add bytes to the in-flight queue, and mark those bytes as consumed.
232 : 169701 : in_flight[side].insert(in_flight[side].end(), bytes.begin(), bytes.begin() + send_now);
233 [ + + ]: 169701 : transports[side]->MarkBytesSent(send_now);
234 : : // If all to-be-sent bytes were sent, move last_more data to expect_more data.
235 [ + + ]: 169701 : if (send_now == bytes.size()) {
236 : 57773 : expect_more[side] = last_more[side];
237 : 57773 : expect_more_next[side] = last_more_next[side];
238 : : }
239 : : // Remove the bytes from the last reported to-be-sent vector.
240 [ - + ]: 169701 : assert(to_send[side].size() >= send_now);
241 : 169701 : to_send[side].erase(to_send[side].begin(), to_send[side].begin() + send_now);
242 : : // Verify that GetBytesToSend gives a result consistent with earlier.
243 : 169701 : bytes_to_send_fn(/*side=*/side);
244 : : // Return whether anything was sent.
245 : 169701 : return send_now > 0;
246 : : };
247 : :
248 : : // Function to make !side receive bytes (if any).
249 : 92860 : auto recv_fn = [&](int side, bool everything = false) {
250 : : // Don't do anything if no bytes in flight.
251 [ + + ]: 91388 : if (in_flight[side].empty()) return false;
252 : : // Decide span to receive
253 [ + + ]: 71201 : size_t to_recv_len = in_flight[side].size();
254 [ + + ]: 71201 : if (!everything) to_recv_len = provider.ConsumeIntegralInRange<size_t>(0, to_recv_len);
255 : 71201 : Span<const uint8_t> to_recv = Span{in_flight[side]}.first(to_recv_len);
256 : : // Process those bytes
257 [ + + ]: 182878 : while (!to_recv.empty()) {
258 : 111677 : size_t old_len = to_recv.size();
259 : 111677 : bool ret = transports[!side]->ReceivedBytes(to_recv);
260 : : // Bytes must always be accepted, as this test does not introduce any errors in
261 : : // communication.
262 [ - + ]: 111677 : assert(ret);
263 : : // Clear cached expected 'more' information: if certainly no more data was to be sent
264 : : // before, receiving bytes makes this uncertain.
265 [ + + ]: 116660 : if (expect_more[!side] == false) expect_more[!side] = std::nullopt;
266 [ + + ]: 111888 : if (expect_more_next[!side] == false) expect_more_next[!side] = std::nullopt;
267 : : // Verify consistency of GetBytesToSend after ReceivedBytes
268 : 111677 : bytes_to_send_fn(/*side=*/!side);
269 : 111677 : bool progress = to_recv.size() < old_len;
270 [ + + ]: 111677 : if (transports[!side]->ReceivedMessageComplete()) {
271 : 46883 : bool reject{false};
272 : 46883 : auto received = transports[!side]->GetReceivedMessage({}, reject);
273 : : // Receiving must succeed.
274 [ - + ]: 46883 : assert(!reject);
275 : : // There must be a corresponding expected message.
276 [ - + ]: 46883 : assert(!expected[side].empty());
277 : : // The m_message_size field must be correct.
278 [ - + ]: 46883 : assert(received.m_message_size == received.m_recv.size());
279 : : // The m_type must match what is expected.
280 [ - + ]: 46883 : assert(received.m_type == expected[side].front().m_type);
281 : : // The data must match what is expected.
282 [ - + ]: 46883 : assert(std::ranges::equal(received.m_recv, MakeByteSpan(expected[side].front().data)));
283 : 46883 : expected[side].pop_front();
284 : 46883 : progress = true;
285 : 46883 : }
286 : : // Progress must be made (by processing incoming bytes and/or returning complete
287 : : // messages) until all received bytes are processed.
288 [ - + ]: 111677 : assert(progress);
289 : : }
290 : : // Remove the processed bytes from the in_flight buffer.
291 : 71201 : in_flight[side].erase(in_flight[side].begin(), in_flight[side].begin() + to_recv_len);
292 : : // Return whether anything was received.
293 : 71201 : return to_recv_len > 0;
294 : : };
295 : :
296 : : // Main loop, interleaving new messages, sends, and receives.
297 [ + + + + ]: 589391 : LIMITED_WHILE(provider.remaining_bytes(), 1000) {
298 [ + - ]: 587919 : CallOneOf(provider,
299 : : // (Try to) give the next message to the transport.
300 : 169248 : [&] { new_msg_fn(/*side=*/0); },
301 : 63201 : [&] { new_msg_fn(/*side=*/1); },
302 : : // (Try to) send some bytes from the transport to the network.
303 : 93943 : [&] { send_fn(/*side=*/0); },
304 : 177291 : [&] { send_fn(/*side=*/1); },
305 : : // (Try to) receive bytes from the network, converting to messages.
306 : 47595 : [&] { recv_fn(/*side=*/0); },
307 : 36641 : [&] { recv_fn(/*side=*/1); }
308 : : );
309 : : }
310 : :
311 : : // When we're done, perform sends and receives of existing messages to flush anything already
312 : : // in flight.
313 : : while (true) {
314 : 3576 : bool any = false;
315 [ + - + + ]: 3576 : if (send_fn(/*side=*/0, /*everything=*/true)) any = true;
316 [ + - + + ]: 3576 : if (send_fn(/*side=*/1, /*everything=*/true)) any = true;
317 [ + - + + ]: 3576 : if (recv_fn(/*side=*/0, /*everything=*/true)) any = true;
318 [ + - + + ]: 3576 : if (recv_fn(/*side=*/1, /*everything=*/true)) any = true;
319 [ + + ]: 3576 : if (!any) break;
320 : : }
321 : :
322 : : // Make sure nothing is left in flight.
323 [ - + ]: 1472 : assert(in_flight[0].empty());
324 [ - + ]: 1472 : assert(in_flight[1].empty());
325 : :
326 : : // Make sure all expected messages were received.
327 [ - + ]: 1472 : assert(expected[0].empty());
328 [ - + ]: 1472 : assert(expected[1].empty());
329 : :
330 : : // Compare session IDs.
331 [ - + ]: 1472 : assert(transports[0]->GetInfo().session_id == transports[1]->GetInfo().session_id);
332 : 5888 : }
333 : :
334 : 1230 : std::unique_ptr<Transport> MakeV1Transport(NodeId nodeid) noexcept
335 : : {
336 [ - + ]: 1230 : return std::make_unique<V1Transport>(nodeid);
337 : : }
338 : :
339 : : template<RandomNumberGenerator RNG>
340 : 1900 : std::unique_ptr<Transport> MakeV2Transport(NodeId nodeid, bool initiator, RNG& rng, FuzzedDataProvider& provider)
341 : : {
342 : : // Retrieve key
343 [ + + ]: 1900 : auto key = ConsumePrivateKey(provider);
344 [ + + ]: 1900 : if (!key.IsValid()) return {};
345 : : // Construct garbage
346 : 1798 : size_t garb_len = provider.ConsumeIntegralInRange<size_t>(0, V2Transport::MAX_GARBAGE_LEN);
347 : 1798 : std::vector<uint8_t> garb;
348 [ + + ]: 1798 : if (garb_len <= 64) {
349 : : // When the garbage length is up to 64 bytes, read it directly from the fuzzer input.
350 [ + - ]: 1450 : garb = provider.ConsumeBytes<uint8_t>(garb_len);
351 [ + - ]: 725 : garb.resize(garb_len);
352 : : } else {
353 : : // If it's longer, generate it from the RNG. This avoids having large amounts of
354 : : // (hopefully) irrelevant data needing to be stored in the fuzzer data.
355 : 1073 : garb = rng.randbytes(garb_len);
356 : : }
357 : : // Retrieve entropy
358 [ + - ]: 1798 : auto ent = provider.ConsumeBytes<std::byte>(32);
359 [ + - ]: 1798 : ent.resize(32);
360 : : // Use as entropy SHA256(ent || garbage). This prevents a situation where the fuzzer manages to
361 : : // include the garbage terminator (which is a function of both ellswift keys) in the garbage.
362 : : // This is extremely unlikely (~2^-116) with random keys/garbage, but the fuzzer can choose
363 : : // both non-randomly and dependently. Since the entropy is hashed anyway inside the ellswift
364 : : // computation, no coverage should be lost by using a hash as entropy, and it removes the
365 : : // possibility of garbage that happens to contain what is effectively a hash of the keys.
366 [ + - + - : 1798 : CSHA256().Write(UCharCast(ent.data()), ent.size())
+ - ]
367 [ + - + - ]: 1798 : .Write(garb.data(), garb.size())
368 [ + - ]: 1798 : .Finalize(UCharCast(ent.data()));
369 : :
370 [ + - - + ]: 1798 : return std::make_unique<V2Transport>(nodeid, initiator, key, ent, std::move(garb));
371 : 3698 : }
372 : :
373 : : } // namespace
374 : :
375 [ + - ]: 784 : FUZZ_TARGET(p2p_transport_bidirectional, .init = initialize_p2p_transport_serialization)
376 : : {
377 : : // Test with two V1 transports talking to each other.
378 : 372 : FuzzedDataProvider provider{buffer.data(), buffer.size()};
379 : 372 : InsecureRandomContext rng(provider.ConsumeIntegral<uint64_t>());
380 : 372 : auto t1 = MakeV1Transport(NodeId{0});
381 : 372 : auto t2 = MakeV1Transport(NodeId{1});
382 [ + - - + ]: 372 : if (!t1 || !t2) return;
383 [ + - ]: 372 : SimulationTest(*t1, *t2, rng, provider);
384 : 372 : }
385 : :
386 [ + - ]: 1119 : FUZZ_TARGET(p2p_transport_bidirectional_v2, .init = initialize_p2p_transport_serialization)
387 : : {
388 : : // Test with two V2 transports talking to each other.
389 : 707 : FuzzedDataProvider provider{buffer.data(), buffer.size()};
390 : 707 : InsecureRandomContext rng(provider.ConsumeIntegral<uint64_t>());
391 : 707 : auto t1 = MakeV2Transport(NodeId{0}, true, rng, provider);
392 [ + - ]: 707 : auto t2 = MakeV2Transport(NodeId{1}, false, rng, provider);
393 [ + + + + ]: 707 : if (!t1 || !t2) return;
394 [ + - ]: 625 : SimulationTest(*t1, *t2, rng, provider);
395 : 707 : }
396 : :
397 [ + - ]: 898 : FUZZ_TARGET(p2p_transport_bidirectional_v1v2, .init = initialize_p2p_transport_serialization)
398 : : {
399 : : // Test with a V1 initiator talking to a V2 responder.
400 : 486 : FuzzedDataProvider provider{buffer.data(), buffer.size()};
401 : 486 : InsecureRandomContext rng(provider.ConsumeIntegral<uint64_t>());
402 : 486 : auto t1 = MakeV1Transport(NodeId{0});
403 [ + - ]: 486 : auto t2 = MakeV2Transport(NodeId{1}, false, rng, provider);
404 [ + - + + ]: 486 : if (!t1 || !t2) return;
405 [ + - ]: 475 : SimulationTest(*t1, *t2, rng, provider);
406 : 486 : }
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