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<?php |
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namespace Helix\Socket\WebSocket; |
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use Throwable; |
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/** |
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* Initial WebSocket connection handshake. |
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* |
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* https://tools.ietf.org/html/rfc6455#section-1.3 |
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*/ |
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class Handshake { |
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const RFC_GUID = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'; |
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/** |
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* @var string |
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*/ |
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protected $buffer = ''; |
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/** |
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* @var WebSocketClient |
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*/ |
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protected $client; |
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/** |
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* [ header name => lowercase value => actual value ] |
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* |
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* @var string[][] |
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*/ |
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protected $headers = []; |
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/** |
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* The connection is closed (HTTP 413) if the received headers exceed this many bytes. |
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* |
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* @var int |
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*/ |
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protected $maxLength = 4096; |
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/** |
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* @var string |
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*/ |
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protected $method; |
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/** |
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* @param WebSocketClient $client |
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*/ |
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public function __construct (WebSocketClient $client) { |
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$this->client = $client; |
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} |
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/** |
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* @return string[][] |
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*/ |
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public function getHeaders () { |
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return $this->headers; |
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} |
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/** |
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* @return string |
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*/ |
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public function getMethod (): string { |
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return $this->method; |
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} |
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/** |
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* Negotiates the initial connection. |
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* |
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* @return bool |
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* @throws WebSocketError |
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* @throws Throwable |
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*/ |
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public function onReadable (): bool { |
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// read into the buffer |
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$this->buffer .= $bytes = $this->client->recvAll(); |
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// check for peer disconnection |
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if (!strlen($bytes)) { |
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$this->client->close(); |
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return false; |
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} |
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// read frames from the buffer and yield |
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try { |
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// length check |
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if (strlen($this->buffer) > $this->maxLength) { |
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throw new WebSocketError(413, "{$this->client} exceeded the maximum handshake size."); |
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} |
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// still reading? |
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if (false === $end = strpos($this->buffer, "\r\n\r\n")) { |
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return false; |
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} |
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// parse the headers |
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$head = explode("\r\n", substr($this->buffer, 0, $end)); |
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$this->method = array_shift($head); |
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foreach ($head as $header) { |
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$header = explode(':', $header, 2); |
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if (count($header) !== 2) { |
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throw new WebSocketError(400, "{$this->client} sent a malformed header."); |
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} |
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[$key, $value] = $header; |
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$key = strtolower(trim($key)); |
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foreach (explode(', ', $value) as $value) { |
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$value = trim($value); |
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$this->headers[$key][strtolower($value)] = $value; |
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} |
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} |
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$this->buffer = ''; // wipe the buffer |
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$this->validate(); |
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} |
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catch (WebSocketError $e) { // catch and respond with HTTP error and rethrow |
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$this->client->write("HTTP/1.1 {$e->getCode()} WebSocket Handshake Failure\r\n\r\n"); |
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throw $e; |
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} |
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catch (Throwable $e) { // catch everything else and respond with HTTP 500 and rethrow |
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$this->client->write("HTTP/1.1 500 WebSocket Internal Error\r\n\r\n"); |
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throw $e; |
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} |
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// send upgrade headers |
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$this->upgrade(); |
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$this->client->write("\r\n\r\n"); |
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// success |
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return true; |
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} |
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/** |
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* Sends the connection upgrade headers. |
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*/ |
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protected function upgrade (): void { |
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$key = base64_encode(sha1(current($this->headers['sec-websocket-key']) . self::RFC_GUID, true)); |
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$this->client->write(implode("\r\n", [ |
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"HTTP/1.1 101 Switching Protocols", |
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"Connection: Upgrade", |
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"Upgrade: websocket", |
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"Sec-WebSocket-Accept: {$key}" |
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])); |
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} |
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/** |
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* Validates the received HTTP handshake headers, or throws. |
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* |
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* @throws WebSocketError |
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*/ |
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protected function validate (): void { |
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if (!( |
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$check = 'method = http 1.1' |
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and preg_match('/HTTP\/1\.1$/i', $this->method) |
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and $check = 'connection = upgrade' |
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and isset($this->headers['connection']['upgrade']) |
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and $check = 'upgrade = websocket' |
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and isset($this->headers['upgrade']['websocket']) |
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and $check = 'version = 13' |
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and isset($this->headers['sec-websocket-version']['13']) |
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and $check = 'key length = 16' |
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and strlen(base64_decode(current($this->headers['sec-websocket-key'] ?? []))) === 16 |
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)) { |
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throw new WebSocketError(400, "Handshake with {$this->client} failed on validation: {$check}"); |
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} |
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} |
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} |
If you define a variable conditionally, it can happen that it is not defined for all execution paths.
Let’s take a look at an example:
In the above example, the variable $x is defined if you pass “foo” or “bar” as argument for $a. However, since the switch statement has no default case statement, if you pass any other value, the variable $x would be undefined.
Available Fixes
Check for existence of the variable explicitly:
Define a default value for the variable:
Add a value for the missing path: