framework/web/Request.php
protected function filterHeaders(HeaderCollection $headerCollection)
    {
        // do not trust any of the [[secureHeaders]] by default
        $trustedHeaders = [];

        // check if the client is a trusted host
        if (!empty($this->trustedHosts)) {
            $validator = $this->getIpValidator();
            $ip = $this->getRemoteIP();
            foreach ($this->trustedHosts as $cidr => $headers) {
                if (!is_array($headers)) {
                    $cidr = $headers;
                    $headers = $this->secureHeaders;
                }
                $validator->setRanges($cidr);
                if ($validator->validate($ip)) {
                    $trustedHeaders = $headers;
                    break;
                }
            }
        }

        // filter all secure headers unless they are trusted
        foreach ($this->secureHeaders as $secureHeader) {
            if (!in_array($secureHeader, $trustedHeaders)) {
                $headerCollection->remove($secureHeader);
            }
        }
    }
protected function filterHeaders(HeaderCollection $headerCollection)
    {
        // do not trust any of the [[secureHeaders]] by default
        $trustedHeaders = [];

        // check if the client is a trusted host
        if (!empty($this->trustedHosts)) {
            $validator = $this->getIpValidator();
            $ip = $this->getRemoteIP();
            foreach ($this->trustedHosts as $cidr => $headers) {
                if (!is_array($headers)) {
                    $cidr = $headers;
                    $headers = $this->secureHeaders;
                }
                $validator->setRanges($cidr);
                if ($validator->validate($ip)) {
                    $trustedHeaders = $headers;
                    break;
                }
            }
        }

        // filter all secure headers unless they are trusted
        foreach ($this->secureHeaders as $secureHeader) {
            if (!in_array($secureHeader, $trustedHeaders)) {
                $headerCollection->remove($secureHeader);
            }
        }
    }
Filters headers according to the [[trustedHosts]].
@param HeaderCollection $headerCollection
@since 2.0.13