class.datasource.dynamic_xml.php

<?php

/**
 * @package data-sources
 */
/**
 * The `DynamicXMLDatasource` allows a user to retrieve XML from an URL.
 * This datasource supports namespaces, partial results using XPath and
 * caching the result for a number of minutes.
 *
 * @since Symphony 2.3
 */

require_once TOOLKIT . '/class.gateway.php';
require_once TOOLKIT . '/class.xsltprocess.php';
require_once CORE . '/class.cacheable.php';

class DynamicXMLDatasource extends Datasource
{
    public function execute(array &$param_pool = null)
    {
        $result = new XMLElement($this->dsParamROOTELEMENT);

        $this->dsParamURL = $this->parseParamURL($this->dsParamURL);

        if (isset($this->dsParamXPATH)) {
            $this->dsParamXPATH = $this->__processParametersInString($this->dsParamXPATH, $this->_env);
        }

        $stylesheet = new XMLElement('xsl:stylesheet');
        $stylesheet->setAttributeArray(array('version' => '1.0', 'xmlns:xsl' => 'http://www.w3.org/1999/XSL/Transform'));

        $output = new XMLElement('xsl:output');
        $output->setAttributeArray(array('method' => 'xml', 'version' => '1.0', 'encoding' => 'utf-8', 'indent' => 'yes', 'omit-xml-declaration' => 'yes'));
        $stylesheet->appendChild($output);

        $template = new XMLElement('xsl:template');
        $template->setAttribute('match', '/');

        $instruction = new XMLElement('xsl:copy-of');

        // Namespaces
        if (isset($this->dsParamFILTERS) && is_array($this->dsParamFILTERS)) {
            foreach ($this->dsParamFILTERS as $name => $uri) {
                $instruction->setAttribute('xmlns' . ($name ? ":{$name}" : null), $uri);
            }
        }

        // XPath
        $instruction->setAttribute('select', $this->dsParamXPATH);

        $template->appendChild($instruction);
        $stylesheet->appendChild($template);

        $stylesheet->setIncludeHeader(true);

        $xsl = $stylesheet->generate(true);

        $cache_id = md5($this->dsParamURL . serialize($this->dsParamFILTERS) . $this->dsParamXPATH);

        $cache = new Cacheable(Symphony::Database());

        $cachedData = $cache->read($cache_id);
        $writeToCache = false;
        $valid = true;
        $creation = DateTimeObj::get('c');
        $timeout = (isset($this->dsParamTIMEOUT)) ? (int)max(1, $this->dsParamTIMEOUT) : 6;

        // Execute if the cache doesn't exist, or if it is old.
        if (
            (!is_array($cachedData) || empty($cachedData)) // There's no cache.
            || (time() - $cachedData['creation']) > ($this->dsParamCACHE * 60) // The cache is old.
        ) {
            if (Mutex::acquire($cache_id, $timeout, TMP)) {
                $ch = new Gateway;
                $ch->init($this->dsParamURL);
                $ch->setopt('TIMEOUT', $timeout);
                $ch->setopt('HTTPHEADER', array('Accept: text/xml, */*'));

                $data = $ch->exec();
                $info = $ch->getInfoLast();

                Mutex::release($cache_id, TMP);

                $data = trim($data);
                $writeToCache = true;

                // Handle any response that is not a 200, or the content type does not include XML, plain or text
                if ((int)$info['http_code'] !== 200 || !preg_match('/(xml|plain|text)/i', $info['content_type'])) {
                    $writeToCache = false;

                    $result->setAttribute('valid', 'false');

                    // 28 is CURLE_OPERATION_TIMEOUTED
                    if ($info['curl_error'] == 28) {
                        $result->appendChild(
                            new XMLElement('error',
                                sprintf('Request timed out. %d second limit reached.', $timeout)
                            )
                        );
                    } else {
                        $result->appendChild(
                            new XMLElement('error',
                                sprintf('Status code %d was returned. Content-type: %s', $info['http_code'], $info['content_type'])
                            )
                        );
                    }

                    return $result;

                    // Handle where there is `$data`
                } elseif (strlen($data) > 0) {
                    // If the XML doesn't validate..
                    if (!General::validateXML($data, $errors, false, new XsltProcess)) {
                        $writeToCache = false;
                    }

                    // If the `$data` is invalid, return a result explaining why
                    if ($writeToCache === false) {
                        $element = new XMLElement('errors');

                        $result->setAttribute('valid', 'false');

                        $result->appendChild(new XMLElement('error', __('Data returned is invalid.')));

                        foreach ($errors as $e) {
                            if (strlen(trim($e['message'])) == 0) {
                                continue;
                            }

                            $element->appendChild(new XMLElement('item', General::sanitize($e['message'])));
                        }

                        $result->appendChild($element);

                        return $result;
                    }

                    // If `$data` is empty, set the `force_empty_result` to true.
                } elseif (strlen($data) == 0) {
                    $this->_force_empty_result = true;
                }

                // Failed to acquire a lock
            } else {
                $result->appendChild(
                    new XMLElement('error', __('The %s class failed to acquire a lock, check that %s exists and is writable.', array(
                        '<code>Mutex</code>',
                        '<code>' . TMP . '</code>'
                    )))
                );
            }

            // The cache is good, use it!
        } else {
            $data = trim($cachedData['data']);
            $creation = DateTimeObj::get('c', $cachedData['creation']);
        }

        // If `$writeToCache` is set to false, invalidate the old cache if it existed.
        if (is_array($cachedData) && !empty($cachedData) && $writeToCache === false) {
            $data = trim($cachedData['data']);
            $valid = false;
            $creation = DateTimeObj::get('c', $cachedData['creation']);

            if (empty($data)) {
                $this->_force_empty_result = true;
            }
        }

        // If `force_empty_result` is false and `$result` is an instance of
        // XMLElement, build the `$result`.
        if (!$this->_force_empty_result && is_object($result)) {
            $proc = new XsltProcess;
            $ret = $proc->process($data, $xsl);

            if ($proc->isErrors()) {
                $result->setAttribute('valid', 'false');
                $error = new XMLElement('error', __('Transformed XML is invalid.'));
                $result->appendChild($error);
                $element = new XMLElement('errors');

                foreach ($proc->getError() as $e) {
                    if (strlen(trim($e['message'])) == 0) {
                        continue;
                    }

                    $element->appendChild(new XMLElement('item', General::sanitize($e['message'])));
                }

                $result->appendChild($element);
            } elseif (strlen(trim($ret)) == 0) {
                $this->_force_empty_result = true;
            } else {
                if ($writeToCache) {
                    $cache->write($cache_id, $data, $this->dsParamCACHE);
                }

                $result->setValue(PHP_EOL . str_repeat("\t", 2) . preg_replace('/([\r\n]+)/', "$1\t", $ret));
                $result->setAttribute('status', ($valid === true ? 'fresh' : 'stale'));
                $result->setAttribute('creation', $creation);
            }

        }

        return $result;
    }
}