[php] Facebook API - How do I get a Facebook user's profile image through the Facebook API (without requiring the user to "Allow" the application)

There is way to do that ;)

Thanks to "http://it.toolbox.com/wiki/index.php/Use_curl_from_PHP_-_processing_response_headers":

<?php

    /**
     * Facebook user photo downloader
     */

    class sfFacebookPhoto {

        private $useragent = 'Loximi sfFacebookPhoto PHP5 (cURL)';
        private $curl = null;
        private $response_meta_info = array();
        private $header = array(
                "Accept-Encoding: gzip,deflate",
                "Accept-Charset: utf-8;q=0.7,*;q=0.7",
                "Connection: close"
            );

        public function __construct() {
            $this->curl = curl_init();
            register_shutdown_function(array($this, 'shutdown'));
        }

        /**
         * Get the real URL for the picture to use after
         */
        public function getRealUrl($photoLink) {
            curl_setopt($this->curl, CURLOPT_HTTPHEADER, $this->header);
            curl_setopt($this->curl, CURLOPT_RETURNTRANSFER, false);
            curl_setopt($this->curl, CURLOPT_HEADER, false);
            curl_setopt($this->curl, CURLOPT_USERAGENT, $this->useragent);
            curl_setopt($this->curl, CURLOPT_CONNECTTIMEOUT, 10);
            curl_setopt($this->curl, CURLOPT_TIMEOUT, 15);
            curl_setopt($this->curl, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
            curl_setopt($this->curl, CURLOPT_URL, $photoLink);

            //This assumes your code is into a class method, and
            //uses $this->readHeader as the callback function.
            curl_setopt($this->curl, CURLOPT_HEADERFUNCTION, array(&$this, 'readHeader'));
            $response = curl_exec($this->curl);
            if (!curl_errno($this->curl)) {
                $info = curl_getinfo($this->curl);
                var_dump($info);
                if ($info["http_code"] == 302) {
                    $headers = $this->getHeaders();
                    if (isset($headers['fileUrl'])) {
                        return $headers['fileUrl'];
                    }
                }
            }
            return false;
        }


        /**
         * Download Facebook user photo
         *
         */
        public function download($fileName) {
            curl_setopt($this->curl, CURLOPT_HTTPHEADER, $this->header);
            curl_setopt($this->curl, CURLOPT_RETURNTRANSFER, true);
            curl_setopt($this->curl, CURLOPT_HEADER, false);
            curl_setopt($this->curl, CURLOPT_USERAGENT, $this->useragent);
            curl_setopt($this->curl, CURLOPT_CONNECTTIMEOUT, 10);
            curl_setopt($this->curl, CURLOPT_TIMEOUT, 15);
            curl_setopt($this->curl, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
            curl_setopt($this->curl, CURLOPT_URL, $fileName);
            $response = curl_exec($this->curl);
            $return = false;
            if (!curl_errno($this->curl)) {
                $parts = explode('.', $fileName);
                $ext = array_pop($parts);
                $return = sfConfig::get('sf_upload_dir') . '/tmp/' . uniqid('fbphoto') . '.' . $ext;
                file_put_contents($return, $response);
            }
            return $return;
        }

        /**
         * cURL callback function for reading and processing headers.
         * Override this for your needs.
         *
         * @param object $ch
         * @param string $header
         * @return integer
         */
        private function readHeader($ch, $header) {

            //Extracting example data: filename from header field Content-Disposition
            $filename = $this->extractCustomHeader('Location: ', '\n', $header);
            if ($filename) {
                $this->response_meta_info['fileUrl'] = trim($filename);
            }
            return strlen($header);
        }

        private function extractCustomHeader($start, $end, $header) {
            $pattern = '/'. $start .'(.*?)'. $end .'/';
            if (preg_match($pattern, $header, $result)) {
                return $result[1];
            }
            else {
                return false;
            }
        }

        public function getHeaders() {
            return $this->response_meta_info;
        }

        /**
         * Cleanup resources
         */
        public function shutdown() {
            if($this->curl) {
                curl_close($this->curl);
            }
        }
    }