/**
* Parses data from a data buffer into an array representing a frame header
*
* @param \WebSocketServer\Socket\Buffer $buffer The data buffer
*
* @return bool True is a complete frame header was successfully parsed from the buffer
*
* @throws \RangeException When the frame is invalid
*/
private function parseFrameHeader(Buffer $buffer)
{
if ($buffer->length() < 2) {
return false;
}
$firstByte = ord($buffer->read(1, 0, Buffer::READ_PEEK));
$fin = (bool) ($firstByte & 0b10000000);
$rsv = ($firstByte & 0b1110000) >> 4;
$opcode = $firstByte & 0b1111;
$secondByte = ord($buffer->read(1, 1, Buffer::READ_PEEK));
$masked = (bool) ($secondByte & 0b10000000);
$lengthHeader = $secondByte & 0b1111111;
$bytesProcessed = 2;
if ($lengthHeader === 0x7f) {
if ($buffer->length() < 10) {
return false;
}
$lengthLong32Pair = unpack('NN', $buffer->read(8, 2, Buffer::READ_PEEK));
$bytesProcessed += 8;
if (PHP_INT_MAX === 0x7fffffff) {
// Size of packets limited to 2.1GB on 32-bit platforms
// TODO: fix this (although arguably a non-problem, this is a huge security flaw)
if ($lengthLong32Pair[0] !== 0 || $lengthLong32Pair[1] < 0) {
$buffer->read(10);
throw new \RangeException('A frame was received that stated its payload length to be larger than 0x7fffffff bytes, this platform does not support values that large');
}
$length = $lengthLong32Pair[1];
} else {
$length = $lengthLong32Pair[0] << 32 | $lengthLong32Pair[1];
if ($length < 0) {
throw new \RangeException('Invalid frame: Most significant bit of 64-bit length field set');
}
}
} else {
if ($lengthHeader === 0x7e) {
if ($buffer->length() < 4) {
return false;
}
$length = current(unpack('n', $buffer->read(2, 2, Buffer::READ_PEEK)));
$bytesProcessed += 2;
} else {
$length = $lengthHeader;
}
}
if ($masked) {
if ($buffer->length() < $bytesProcessed + 4) {
return false;
}
$maskingKey = $buffer->read(4, $bytesProcessed, Buffer::READ_PEEK);
$bytesProcessed += 4;
} else {
$maskingKey = null;
}
$buffer->read($bytesProcessed);
$this->pendingFrameHeader = ['fin' => $fin, 'rsv' => $rsv, 'opcode' => $opcode, 'masked' => $masked, 'maskingKey' => $maskingKey, 'length' => $length];
return true;
}
