PHP Infine Loop Problem - php

Question

function httpGet( $url, $followRedirects=true ) {
global $final_url;
$url_parsed = parse_url($url);
if ( empty($url_parsed['scheme']) ) {
$url_parsed = parse_url('http://'.$url);
}
$final_url = $url_parsed;
$port = $url_parsed["port"];
if ( !$port ) {
$port = 80;
}
$rtn['url']['port'] = $port;
$path = $url_parsed["path"];
if ( empty($path) ) {
$path="/";
}
if ( !empty($url_parsed["query"]) ) {
$path .= "?".$url_parsed["query"];
}
$rtn['url']['path'] = $path;
$host = $url_parsed["host"];
$foundBody = false;
$out = "GET $path HTTP/1.0\r\n";
$out .= "Host: $host\r\n";
$out .= "User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1) Gecko/20061010 Firefox/2.0\r\n";
$out .= "Connection: Close\r\n\r\n";
if ( !$fp = #fsockopen($host, $port, $errno, $errstr, 30) ) {
$rtn['errornumber'] = $errno;
$rtn['errorstring'] = $errstr;
}
fwrite($fp, $out);
while (!#feof($fp)) {
$s = #fgets($fp, 128);
if ( $s == "\r\n" ) {
$foundBody = true;
continue;
}
if ( $foundBody ) {
$body .= $s;
} else {
if ( ($followRedirects) && (stristr($s, "location:") != false) ) {
$redirect = preg_replace("/location:/i", "", $s);
return httpGet( trim($redirect) );
}
$header .= $s;
}
}
fclose($fp);
return(trim($body));
}
This code sometimes go infinite loop. What's wrong here?

Answer 1

There is a big, red warning box in the feof() documentation:
Warning
If a connection opened by fsockopen() wasn't closed by the server, feof() will hang. To workaround this, see below example:
Example #1 Handling timeouts with feof()
<?php
function safe_feof($fp, &start = NULL) {
$start = microtime(true);
return feof($fp);
}
/* Assuming $fp is previously opened by fsockopen() */
$start = NULL;
$timeout = ini_get('default_socket_timeout');
while(!safe_feof($fp, $start) && (microtime(true) - $start) < $timeout)
{
/* Handle */
}
?>
Also you should only write to or read from the file pointer, if it is valid (what you are not doing, you just set an error message):
This leads to the second big red warning box:
Warning
If the passed file pointer is not valid you may get an infinite loop, because feof() fails to return TRUE.
Better would be:
$result = '';
if ( !$fp = #fsockopen($host, $port, $errno, $errstr, 30) ) {
$rtn['errornumber'] = $errno;
$rtn['errorstring'] = $errstr;
}
else {
fwrite($fp, $out);
while (!#feof($fp)) {
//...
}
fclose($fp);
$result = trim(body);
}
return $result;
A last remark: If you follow a redirect with
if ( ($followRedirects) && (stristr($s, "location:") != false) ) {
$redirect = preg_replace("/location:/i", "", $s);
return httpGet( trim($redirect) );
}
you never close the file pointer. I think better is:
if ( ($followRedirects) && (stristr($s, "location:") != false) ) {
$redirect = preg_replace("/location:/i", "", $s);
$result = httpGet( trim($redirect) );
break;
}
// ...
return $result;

Answer 2

feof will return false if the connection is still open in a tcp/ip stream.

Answer 3

function httpGet( $url, $followRedirects=true ) {
[...]
return httpGet( trim($redirect) );
}
Nothing prevents you from fetching the same URL again and again.