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fuzz: minor updates to the Simplicity fuzz tests #1414

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Merged
merged 2 commits into from
Feb 14, 2025
Merged

fuzz: minor updates to the Simplicity fuzz tests #1414

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69c2415
fuzz: update simplicity_tx target to hit simplicity CMR error
apoelstra Feb 13, 2025
a2d24ef
fuzz: remove dead code from simplicity_tx.cpp
apoelstra Feb 13, 2025
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19 changes: 10 additions & 9 deletions src/test/fuzz/simplicity_tx.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <cstdio>
#include <span.h>
#include <primitives/transaction.h>
#include <script/sigcache.h>
Expand Down Expand Up @@ -65,14 +64,6 @@ void initialize_simplicity_tx()
INPUT_ASSET_CONF.vchCommitment[0] = 0x0a;
}

void write_u32(FILE *fh, uint32_t val) {
unsigned char buf[4];

val = htole32(val);
memcpy(buf, &val, 4);
assert(fwrite(buf, 1, 4, fh) == 4);
}

FUZZ_TARGET_INIT(simplicity_tx, initialize_simplicity_tx)
{
simplicity_err error;
Expand Down Expand Up @@ -122,6 +113,7 @@ FUZZ_TARGET_INIT(simplicity_tx, initialize_simplicity_tx)
// 3. Construct `nIn` and `spent_outs` arrays.
bool expect_simplicity = false;
std::vector<CTxOut> spent_outs{};
unsigned char last_cmr[32] = { 0 };
for (unsigned int i = 0; i < mtx.vin.size(); i++) {
// Null asset or value would assert in the interpreter, and are impossible
// to hit in real transactions. Nonces are not included in the UTXO set and
Expand Down Expand Up @@ -160,6 +152,15 @@ FUZZ_TARGET_INIT(simplicity_tx, initialize_simplicity_tx)
// Compute CMR and do some sanity checks on it (and the program)
std::vector<unsigned char> cmr(32, 0);
assert(simplicity_computeCmr(&error, cmr.data(), program.data(), program.size()));
if (error == SIMPLICITY_NO_ERROR) {
if (memcmp(last_cmr, cmr.data(), sizeof(last_cmr)) == 0) {
// If we have already seen this CMR this transaction, try mangling
// it to check that this produces a CMR error and not something worse.
cmr.data()[1] ^= 1;
}
memcpy(last_cmr, cmr.data(), sizeof(last_cmr));
}

const XOnlyPubKey internal{Span{control}.subspan(1, TAPROOT_CONTROL_BASE_SIZE - 1)};

const CScript leaf_script{cmr.begin(), cmr.end()};
Expand Down