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fix: handle undeclared XML namespace prefixes in PROPFIND responses #79

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fix: handle undeclared XML namespace prefixes in PROPFIND responses #79

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33 changes: 31 additions & 2 deletions lib/Service/Remote/RemoteClient.php
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Original file line number Diff line number Diff line change
Expand Up @@ -563,8 +563,16 @@ private function parseMultistatusProperties(IResponse $response): array {
return [];
}

/** @var MultiStatus $multistatus */
$multistatus = (new SabreXmlService())->expect(self::DAV_MULTISTATUS, $body);
try {
$multistatus = (new SabreXmlService())->expect(self::DAV_MULTISTATUS, $body);
} catch (ParseException $e) {
// Some servers (e.g. Fastmail/Cyrus IMAP) return XML containing namespace
// prefixes (e.g. CY:write-properties-resource) that are never declared with
// an xmlns attribute. Inject placeholder declarations so Sabre can parse the
// standard DAV properties we actually need, then retry.
$body = $this->declareUndeclaredNamespacePrefixes($body);
$multistatus = (new SabreXmlService())->expect(self::DAV_MULTISTATUS, $body);
}

$result = [];
foreach ($multistatus->getResponses() as $davResponse) {
Expand All @@ -577,6 +585,27 @@ private function parseMultistatusProperties(IResponse $response): array {
return $result;
}

private function declareUndeclaredNamespacePrefixes(string $xml): string {
preg_match_all('/<(?![\?!\/])([a-zA-Z][a-zA-Z0-9_-]*):/', $xml, $usedMatches);
$usedPrefixes = array_unique(array_filter($usedMatches[1]));

preg_match_all('/\bxmlns:([a-zA-Z][a-zA-Z0-9_-]*)\s*=/', $xml, $declaredMatches);
$declaredPrefixes = array_flip($declaredMatches[1]);

$extra = '';
foreach ($usedPrefixes as $prefix) {
if (!isset($declaredPrefixes[$prefix])) {
$extra .= sprintf(' xmlns:%s="urn:unknown-ns:%s"', $prefix, $prefix);
}
}

if ($extra === '') {
return $xml;
}

return preg_replace('/(<[a-zA-Z:][^>]*?)(\s*\/?>)/', '$1' . $extra . '$2', $xml, 1);
}

/**
* @param array<int, array<string, mixed>> $responseProperties
*/
Expand Down