Unable to download XML file on server, works fine on other - php

Question

I have had an application running successfully for a couple months that relies on a cron job to get an xml feed of air pollution statistics. Since January it has run without error, but this morning from 7:00 it has not read the data. The relevant code is as follows:
<?php
define('FEED_URL', 'http://www.beijingaqifeed.com/BeijingAQI/BeijingAir.xml');
$contents = file_get_contents(FEED_URL);
if ($contents === false) echo "READ FAILED";
echo "FILE_GET_CONTENTS SIZE IS " . strlen($contents) . "<br>\n";
If I run this on my machine at home, it works:
FILE_GET_CONTENTS SIZE IS 21538
If it runs on my server it does not:
FILE_GET_CONTENTS SIZE IS 0
I have confirmed with support at the server site that they can browse the url and see the xml data, so there is no firewall or anything blocking this. And, as I say, this has worked successfully over 1000 times (as measured by entries in my database) until this morning, and now it always fails. I have no connection at the data supplier so I can't investigate from their side.
Can anyone suggest why this started failing, and what I could try doing? I have tried fread() and file(), with the same results.
Thanks...
(I have checked allow_url_fopen is turned on)

Answer 1

It is in this case probaly something on server blocking Your PHP , might be OS update , or something like that. In past I had similar problems , but , mines was about unkillable daemon , linked with cron job , so , me and support team had big headaches of turning it off. In this case , this is crucial for further investigation , this line: FILE_GET_CONTENTS SIZE IS 21538 , if someone could obtain it and read it , there's the catch. This answer might not be helpful at all , but , as I stated , that error line is key.
Odd , I've just checked XML URL , and it works , normally , as it should.

Answer 2

probably permission issue. Try to add the following after file_get_contents to see their response
if (!empty($http_response_header))
{
var_dump($http_response_header);
//to see what tou get back
}

Answer 3

First I thought it would be permissions but, that isn't the case.
Try changing server, maybe your IP is blocked or something?
<?php
function download($website){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$path);
curl_setopt($ch, CURLOPT_FAILONERROR,1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION,1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_TIMEOUT, 15);
$retValue = curl_exec($ch);
curl_close($ch);
return $retValue;
}
$XML = download('http://www.beijingaqifeed.com/BeijingAQI/BeijingAir.xml');
var_dump($XML);
Perform:
wget http://www.beijingaqifeed.com/BeijingAQI/BeijingAir.xml via SSH (if possible) and see the response.

Answer 4

It is most likely that there is 500 error , so - their side. Depends what do they use , but many admins (like me) avoid to point out server errors , replacing them with useless comments or simply , by removing them. This is done to prevent intruders , as error code could stick attacker to server under my administration , and if it gets down - my fault.

Answer 5

This is not a final answer, but it clarifies things somewhat. I tried uploading the file to the server and reading it from there the same way (http:/young-0/testfile.xml) and it succeeded. Then I tried getting "http://www.beijingaqifeed.com" from the server - and that failed. So the bom was a red herring, the connection is being blocked either by my provider (who says it is not them) or the site is refusing connections from my server - thanks to everyone who helped.
For now I have returned to using the twitter feed, which is far less reliable but does have the advantage that I am able to read it.