file_get_contents not fetching the correct JSON - php

Question

I have a peculiar issue.
I have a script which fetches a JSON. It works perfectly fine in the browser (gives the correct json). For eg. accessing the URL
http://example.com/json_feed.php?sid=21662567
in browser gives me following JSON (snippet shown):
{"id":"21662567","title":"Camp and Kayak in Amchi Mumbai. for 1 Booking...
As can be seen, the sid (of URL) and id of JSON match and is the correct json.
But the same URL when accessed via file_get_contents, gives me wrong result. The code is rather trivial and hence, I am completely stumped as to why this will happen.
$json = file_get_contents("http://example.com/json_feed.php?sid=21662567");
echo "<pre>";
var_dump($json);
echo "</pre>";
The JSON response of above code is:
string(573) "{"id":"23160210","title":"Learn about Commodity Markets (Gold\/Silver) for...
As can be seen, sid and id don't match now and the JSON fetched is incorrect.
I tried using curl also, thinking that it could be some format issue, but to no avail. curl also fetches the same incorrect JSON.
At the same time, accessing the original URL in browser will fetch the correct JSON.
Any ideas on what's happening here?
EDIT by Talvinder (14 April, 2014 at 0913 IST)
ISSUE SPOTTED: the script json_feed.php is session dependent and file_get_contents doesn't pass session values. I am not sure how to build the HTTP_REQUEST in cURL. Can someone help me with this? My current cURL code is:
$ch = curl_init();
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.154 Safari/537.36 OPR/20.0.1387.91');
curl_setopt($ch, CURLOPT_URL,$url);
$result=curl_exec($ch);
Where $url is the url given at the beginning of the question.
EDIT by TALVINDER(14 april, 1805 IST)
Killed the links shared earlier as they are dead now.
EDIT by TALVINDER (14 april, 0810 IST):
JSON can be seen here: JSON GENERATOR
file_get_content results can be seen here: file_get_contents script

Answer 1

Without any links that we can investigate, I guess there's some sort of user-agent magic going on.
Try spoofing it with cURL.
Someting like this:
curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.154 Safari/537.36 OPR/20.0.1387.91');
You can use your own user agent or find something else here.
Not 100% this is the issue, but considering the data provided by you, this is the only solution I can think of. I am sure you've double checked that the urls etc are correct in the scripts etc.

Answer 2

Figured out the issue and sharing it here for others to take note of:
Lesson 1
file_get_contents doesn't pass session or cookies to the URL, so don't use it to fetch data from URLs which are session or cookie dependents
cURL is your friend. You will have to build full HTTP request to pass proper session variables
Lesson 2
Session dependent scripts will behave properly when accessed via browser but not when accessed via file_get_contents or partially formed cURL
List item
Lesson 3
When the code is too trivial and yet buggy, Devil is in details - question every little function (apologies for philosophical connotation here :) )
SOLUTION
The json_feed.php I created is session dependent. So it was being naughty when accessed via file_get_contents. With cURL too it wasn't behaving properly.
I changed the cURL to include suggestions given here: Maintaining PHP session while accessing URL via cURL
My final cURL code (which worked is below):
$strCookie = 'PHPSESSID=' . $_COOKIE['PHPSESSID'] . '; path=/';
session_write_close();
$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt( $ch, CURLOPT_COOKIE, $strCookie );
curl_setopt($ch, CURLOPT_URL,$url);
$result = curl_exec($ch);
curl_close($ch);
I hope it saves some time for someone.
Thanks for all the replies.