*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
use DOMDocument;
use XSLTProcessor;
use Symfony\Component\Serializer\Serializer;
use Symfony\Component\Serializer\Encoder\XmlEncoder;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
date_default_timezone_set('UTC');
/**
* Scrape supported websites and perform conversion to RSS.
*/
class Tweeper {
private static $userAgent = "Mozilla/5.0 (Linux; U; Android 4.3; en-us; SM-N900T Build/JSS15J)";
private static $maxConnectionTimeout = 5;
private static $maxConnectionRetries = 5;
/**
* Create a new Tweeper object controlling optional settings.
*
* @param bool $generate_enclosure
* Enables the creation of elements (disabled by default).
* @param bool $show_usernames
* Enables showing the username in front of the content for multi-user
* sites (enabled by default). Only some stylesheets supports this
* functionality (twitter, instagram, pump.io).
* @param bool $show_multimedia
* Enables showing multimedia content (images, videos) directly in the
* item description (enabled by default). Only some stylesheets supports
* this functionality (twitter, instagram, dilbert).
* @param bool $verbose_output
* Enables showing non-fatal errors like XML parsing errors.
*/
public function __construct($generate_enclosure = FALSE, $show_usernames = TRUE, $show_multimedia = TRUE, $verbose_output = TRUE) {
$this->generate_enclosure = $generate_enclosure;
$this->show_usernames = $show_usernames;
$this->show_multimedia = $show_multimedia;
$this->verbose_output = $verbose_output;
}
/**
* Convert numeric Epoch to the date format expected in a RSS document.
*/
public static function epochToRssDate($timestamp) {
if (!is_numeric($timestamp) || is_nan($timestamp)) {
$timestamp = 0;
}
return gmdate(DATE_RSS, $timestamp);
}
/**
* Convert generic date string to the date format expected in a RSS document.
*/
public static function strToRssDate($date) {
$timestamp = strtotime($date);
if (FALSE === $timestamp) {
$timestamp = 0;
}
return Tweeper::epochToRssDate($timestamp);
}
/**
* Convert Twitter mobile date to the date format expected in a RSS document.
*/
public static function twitterToRssDate($date) {
// Twitter uses relative timestamps in minutes for recent tweets.
if (preg_match('/^(\d+)m$/', $date, $matches)) {
$timestamp = strtotime("+" . $matches[1] . " min", time());
if (FALSE === $timestamp) {
$timestamp = 0;
}
}
else {
/*
* In case the time is specified put it after the date,
* to make it recognized by strptime().
*/
if (preg_match('/(.*) - (.*)/', $date, $matches)) {
$date = $matches[2] . " " . $matches[1];
}
$timestamp = strtotime($date);
if (FALSE === $timestamp) {
$timestamp = 0;
}
/*
* The twitter mobile UI usually only specifies the month and the day, so
* strtotime($date) may interpret the date as being in the future.
*
* If the date is in the future it is probably in the same day but in the
* previous year.
*/
if ($timestamp > time()) {
$timestamp = strtotime('-1 years', $timestamp);
}
}
return Tweeper::epochToRssDate($timestamp);
}
/**
* Convert string to UpperCamelCase.
*/
public static function toUpperCamelCase($str, $delim = ' ') {
$str_upper = ucwords($str, $delim);
$str_camel_case = str_replace($delim, '', $str_upper);
return $str_camel_case;
}
/**
* Perform a cURL session multiple times when it fails with a timeout.
*
* @param resource $ch
* a cURL session handle.
*/
private static function curlExec($ch) {
$ret = FALSE;
$attempt = 0;
do {
$ret = curl_exec($ch);
if (FALSE === $ret) {
trigger_error(curl_error($ch), E_USER_WARNING);
}
} while (curl_errno($ch) == CURLE_OPERATION_TIMEDOUT && ++$attempt < Tweeper::$maxConnectionRetries);
return $ret;
}
/**
* Get the contents from a URL.
*/
private static function getUrlContents($url) {
$ch = curl_init($url);
curl_setopt_array($ch, array(
CURLOPT_HEADER => FALSE,
CURLOPT_CONNECTTIMEOUT => Tweeper::$maxConnectionTimeout,
// Follow http redirects to get the real URL.
CURLOPT_FOLLOWLOCATION => TRUE,
CURLOPT_COOKIEFILE => "",
CURLOPT_RETURNTRANSFER => TRUE,
CURLOPT_HTTPHEADER => array('Accept-language: en'),
CURLOPT_USERAGENT => Tweeper::$userAgent,
));
$contents = Tweeper::curlExec($ch);
curl_close($ch);
return $contents;
}
/**
* Get the headers from a URL.
*/
private static function getUrlInfo($url) {
$ch = curl_init($url);
curl_setopt_array($ch, array(
CURLOPT_HEADER => TRUE,
CURLOPT_NOBODY => TRUE,
CURLOPT_CONNECTTIMEOUT => Tweeper::$maxConnectionTimeout,
// Follow http redirects to get the real URL.
CURLOPT_FOLLOWLOCATION => TRUE,
CURLOPT_RETURNTRANSFER => TRUE,
CURLOPT_USERAGENT => Tweeper::$userAgent,
));
$ret = Tweeper::curlExec($ch);
if (FALSE === $ret) {
curl_close($ch);
return FALSE;
}
$url_info = curl_getinfo($ch);
if (FALSE === $url_info) {
trigger_error(curl_error($ch), E_USER_WARNING);
}
curl_close($ch);
return $url_info;
}
/**
* Generate an RSS element.
*/
public static function generateEnclosure($url) {
$supported_content_types = array(
"application/octet-stream",
"application/ogg",
"application/pdf",
"audio/aac",
"audio/mp4",
"audio/mpeg",
"audio/ogg",
"audio/vorbis",
"audio/wav",
"audio/webm",
"audio/x-midi",
"image/gif",
"image/jpeg",
"image/png",
"video/avi",
"video/mp4",
"video/mpeg",
"video/ogg",
);
$url_info = Tweeper::getUrlInfo($url);
if (FALSE === $url_info) {
trigger_error("Failed to retrieve info for URL: " . $url, E_USER_WARNING);
return '';
}
$supported = in_array($url_info['content_type'], $supported_content_types);
if (!$supported) {
trigger_error("Unsupported enclosure content type \"" . $url_info['content_type'] . "\" for URL: " . $url_info['url'], E_USER_WARNING);
return '';
}
// The RSS specification says that the enclosure element URL must be http.
// See http://sourceforge.net/p/feedvalidator/bugs/72/
$http_url = preg_replace("/^https/", "http", $url_info['url']);
// When the server does not provide a Content-Length header,
// curl_getinfo() would return a negative value for
// "download_content_length", however RSS recommends to use 0 when the
// enclosure's size cannot be determined.
// See: https://www.feedvalidator.org/docs/error/UseZeroForUnknown.html
$length = max($url_info['download_content_length'], 0);
$dom = new DOMDocument();
$enc = $dom->createElement('enclosure');
$enc->setAttribute('url', $http_url);
$enc->setAttribute('length', $length);
$enc->setAttribute('type', $url_info['content_type']);
return $enc;
}
/**
* Mimic the message from libxml.c::php_libxml_ctx_error_level()
*/
private static function logXmlError($error) {
$output = "";
switch ($error->level) {
case LIBXML_ERR_WARNING:
$output .= "Warning $error->code: ";
break;
case LIBXML_ERR_ERROR:
$output .= "Error $error->code: ";
break;
case LIBXML_ERR_FATAL:
$output .= "Fatal Error $error->code: ";
break;
}
$output .= trim($error->message);
if ($error->file) {
$output .= " in $error->file";
}
else {
$output .= " in Entity,";
}
$output .= " line $error->line";
trigger_error($output, E_USER_WARNING);
}
/**
* Convert json to XML.
*/
private static function jsonToXml($json, $root_node_name) {
// Apparently the ObjectNormalizer used afterwards is not able to handle
// the stdClass object created by json_decode() with the default setting
// $assoc = false; so use $assoc = true.
$data = json_decode($json, $assoc = TRUE);
if (!$data) {
return NULL;
}
$encoder = new XmlEncoder();
$normalizer = new ObjectNormalizer();
$serializer = new Serializer(array($normalizer), array($encoder));
$serializer_options = array(
'xml_encoding' => "UTF-8",
'xml_format_output' => TRUE,
'xml_root_node_name' => $root_node_name,
);
$xml_data = $serializer->serialize($data, 'xml', $serializer_options);
if (!$xml_data) {
trigger_error("Cannot serialize data", E_USER_WARNING);
return NULL;
}
return $xml_data;
}
/**
* Convert the Instagram content to XML.
*/
private function getXmlInstagramCom($html) {
// Extract the json data from the html code.
$json_match_expr = '/window._sharedData = (.*);/';
$ret = preg_match($json_match_expr, $html, $matches);
if ($ret !== 1) {
trigger_error("Cannot match expression: $json_match_expr\n", E_USER_WARNING);
return NULL;
}
$data = json_decode($matches[1], $assoc = TRUE);
// The "qe" object contains elements which will result in invalid XML
// element names, so remove it.
unset($data["qe"]);
// The "knobs" object contains elements with undefined namespaces, so
// remove it to silence an error message.
unset($data["knobs"]);
$json = json_encode($data);
return Tweeper::jsonToXml($json, 'instagram');
}
/**
* Make the Facebook HTML processable.
*/
private function preprocessHtmlFacebookCom($html) {
$html = str_replace('', '', $html);
return $html;
}
/**
* Convert the HTML retrieved from the site to XML.
*/
private function htmlToXml($html, $host) {
$xmlDoc = new DOMDocument();
// Handle warnings and errors when loading invalid HTML.
$xml_errors_value = libxml_use_internal_errors(TRUE);
// If there is a host-specific method to get the XML data, use it!
$get_xml_host_method = 'getXml' . Tweeper::toUpperCamelCase($host, '.');
if (method_exists($this, $get_xml_host_method)) {
$xml_data = call_user_func_array(array($this, $get_xml_host_method), array($html));
$xmlDoc->loadXML($xml_data);
}
else {
$xmlDoc->loadHTML($html);
}
if ($this->verbose_output) {
foreach (libxml_get_errors() as $xml_error) {
Tweeper::logXmlError($xml_error);
}
}
libxml_clear_errors();
libxml_use_internal_errors($xml_errors_value);
return $xmlDoc;
}
/**
* Load a stylesheet if the web site is supported.
*/
private function loadStylesheet($host) {
$stylesheet = "file://" . __DIR__ . "/rss_converter_" . $host . ".xsl";
if (FALSE === file_exists($stylesheet)) {
trigger_error("Conversion to RSS not supported for $host ($stylesheet not found)", E_USER_WARNING);
return NULL;
}
$stylesheet_contents = Tweeper::getUrlContents($stylesheet);
if (FALSE === $stylesheet_contents) {
trigger_error("Cannot open $stylesheet", E_USER_WARNING);
return NULL;
}
$xslDoc = new DOMDocument();
$xslDoc->loadXML($stylesheet_contents);
$xsltProcessor = new XSLTProcessor();
$xsltProcessor->registerPHPFunctions();
$xsltProcessor->setParameter('', 'generate-enclosure', $this->generate_enclosure);
$xsltProcessor->setParameter('', 'show-usernames', $this->show_usernames);
$xsltProcessor->setParameter('', 'show-multimedia', $this->show_multimedia);
$xsltProcessor->importStylesheet($xslDoc);
return $xsltProcessor;
}
/**
* Convert the site content to RSS.
*/
public function tweep($src_url, $host = NULL, $validate_scheme = TRUE) {
$url = parse_url($src_url);
if (FALSE === $url) {
trigger_error("Invalid URL: $src_url", E_USER_WARNING);
return NULL;
}
if (TRUE === $validate_scheme) {
$scheme = $url["scheme"];
if (!in_array($scheme, array("http", "https"))) {
trigger_error("unsupported scheme: $scheme", E_USER_WARNING);
return NULL;
}
}
// If the host is not given derive it from the URL.
if (NULL === $host) {
if (empty($url["host"])) {
trigger_error("Invalid host in URL: $src_url", E_USER_WARNING);
return NULL;
}
// Strip the leading www. to be more forgiving on input URLs.
$host = preg_replace('/^www\./', '', $url["host"]);
}
$xsltProcessor = $this->loadStylesheet($host);
if (NULL === $xsltProcessor) {
return NULL;
}
$html = Tweeper::getUrlContents($src_url);
if (FALSE === $html) {
trigger_error("Failed to retrieve $src_url", E_USER_WARNING);
return NULL;
}
$preprocess_html_host_method = 'preprocessHtml' . Tweeper::toUpperCamelCase($host, '.');
if (method_exists($this, $preprocess_html_host_method)) {
$html = call_user_func_array(array($this, $preprocess_html_host_method), array($html));
}
$xmlDoc = $this->htmlToXml($html, $host);
if (NULL === $xmlDoc) {
return NULL;
}
$output = $xsltProcessor->transformToXML($xmlDoc);
if (FALSE === $output) {
trigger_error('XSL transformation failed.', E_USER_WARNING);
return NULL;
}
return $output;
}
}