fix: ensure csrf token is string

[datlechin]

Description
Make sure the CSRF token must be a string, because hackers can fake the request and pass csrf_main as an array, the system will break 500.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[michalsn]

The same check should be made for php:://input data.

[neznaika0]

Look at this:

    private function getPostedToken(RequestInterface $request): ?string
    {
        assert($request instanceof IncomingRequest);

        // Does the token exist in POST, HEADER or optionally php:://input - json data or PUT, DELETE, PATCH - raw data.

        if ($tokenValue = $request->getPost($this->config->tokenName)) {
            return is_string($tokenValue) ? $tokenValue : null;
        }

        if ($request->hasHeader($this->config->headerName)
            && $request->header($this->config->headerName)->getValue() !== ''
            && $request->header($this->config->headerName)->getValue() !== []) {
            return $request->header($this->config->headerName)->getValue();
        }

        $body = (string) $request->getBody();

        if ($body !== '') {
            $json = json_decode($body);
            if ($json !== null && json_last_error() === JSON_ERROR_NONE) {
                return (isset($json->{$this->config->tokenName}) && is_string($json->{$this->config->tokenName}))
                    ? $json->{$this->config->tokenName}
                    : null;
            }

            parse_str($body, $parsed);

            return (isset($parsed[$this->config->tokenName]) && is_string($parsed[$this->config->tokenName]))
                ? $parsed[$this->config->tokenName]
                : null;
        }

        return null;
    }

[michalsn]

Thanks! Please also handle the case where the CSRF token comes from the php://input.

Your commits have to be signed:

• https://github.com/codeigniter4/CodeIgniter4/blob/develop/contributing/workflow.md#gpg-signing-old-commits
• https://github.com/codeigniter4/CodeIgniter4/blob/develop/contributing/signing.md

You can fix the code style with the command:

composer cs-fix

[paulbalandan]

You can use $this->getPrivateMethod() instead of making this method.