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[stable18] Fix push notifications for multibyte notifications #576

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Merged
rullzer merged 1 commit into from
Mar 2, 2020
Merged

[stable18] Fix push notifications for multibyte notifications #576

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35 changes: 27 additions & 8 deletions lib/Push.php
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Original file line number Diff line number Diff line change
Expand Up @@ -262,14 +262,12 @@ protected function encryptAndSign(Key $userKey, array $device, int $id, INotific
'id' => $notification->getObjectId(),
];

// Max length of encryption is 255, so we need to shorten the subject to be shorter
$subject = $notification->getParsedSubject();
// Half the length for multibyte characters like Russian, Chinese, Japanese, Emojis, …
$dataLength = floor((245 - strlen(json_encode($data))) / 2) - 1;
if (strlen($subject) > $dataLength) {
$data['subject'] = mb_substr($subject, 0, $dataLength) . '…';
} else {
$data['subject'] = $subject;
// Max length of encryption is 255, so we need to make sure the subject is shorter.
// We also substract a buffer of 10 bytes.
$maxDataLength = 255 - strlen(json_encode($data)) - 10;
$data['subject'] = $this->shortenJsonEncodedMultibyte($notification->getParsedSubject(), $maxDataLength);
if ($notification->getParsedSubject() !== $data['subject']) {
$data['subject'] .= '…';
}

if ($isTalkNotification) {
Expand Down Expand Up @@ -299,6 +297,27 @@ protected function encryptAndSign(Key $userKey, array $device, int $id, INotific
];
}

/**
* json_encode is messing with multibyte characters a lot,
* replacing them with something along "\u1234".
* The data length in our encryption is a hard limit, but we don't want to
* make non-utf8 subjects unnecessary short. So this function tries to cut
* it off first.
* If that is not enough it always cuts off 5 characters in multibyte-safe
* fashion until the json_encode-d string is shorter then the given limit.
*
* @param string $subject
* @param int $dataLength
* @return string
*/
protected function shortenJsonEncodedMultibyte(string $subject, int $dataLength): string {
$temp = mb_substr($subject, 0, $dataLength);
while (strlen(json_encode($temp)) > $dataLength) {
$temp = mb_substr($temp, 0, -5);
}
return $temp;
}

/**
* @param Key $userKey
* @param array $device
Expand Down