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Log a warning when a regex condition hits a PCRE error #44

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15 changes: 14 additions & 1 deletion Model/Rule.php
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Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,11 @@ private function scalarValueMatchesCondition(string $value, Condition $condition

switch ($condition->type) {
case 'regex':
return (bool)preg_match('/' . str_replace('/', '\/', $condition->value) . '/', $value);
$result = preg_match('/' . str_replace('/', '\/', $condition->value) . '/', $value);
if ($result === false) {
$this->logPcreFailure($condition);
}
return (bool)$result;
case 'contains':
return strpos($value, $condition->value) !== false;
case 'equals':
Expand All @@ -131,6 +135,15 @@ private function scalarValueMatchesCondition(string $value, Condition $condition
}
}

private function logPcreFailure(Condition $condition): void
{
$this->logger->warning('Regex condition failed with a PCRE error.', [
'error' => function_exists('preg_last_error_msg') ? preg_last_error_msg() : preg_last_error(),
'target' => $condition->target,
'pattern' => $condition->value
]);
}

private function targetValueMatchesCondition($value, Condition $condition): bool
{
if ($condition->type === 'network') {
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21 changes: 21 additions & 0 deletions Test/Model/RuleTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -146,6 +146,27 @@ public function testRuleWithMultipleConditions()
$this->assertTrue($rule->matches($request));
}

public function testRuleRegexLogsAndFailsOpenOnPcreError()
{
$originalBacktrackLimit = ini_get('pcre.backtrack_limit');
ini_set('pcre.backtrack_limit', '1');

try {
$logger = $this->createMock(Logger::class);
$logger->expects($this->once())->method('warning');
$request = $this->createConfiguredMock(Http::class, [
'getContent' => str_repeat('a', 50) . 'X'
]);
$rule = new Rule(new IP(), $logger, 'block', [
new Condition('req.body', 'regex', '(a+)+$')
]);

$this->assertFalse($rule->matches($request));
} finally {
ini_set('pcre.backtrack_limit', $originalBacktrackLimit);
}
}

public function testRuleWithoutConditions()
{
$rule = new Rule(new IP(), $this->createMock(Logger::class), 'block', []);
Expand Down