Exit out of a cURL fetch - php

Question

I'm trying to find a way to only quickly access a file and then disconnect immediately.
So I've decided to use cURL since it's the fastest option for me. But I can't figure out how I should "disconnect" cURL.
With the code below, Apache's access logs says that the file I tried accessing was indeed accessed, but I'm feeling a little iffy about this, because when I just run the while loop without breaking out of it, it just keeps looping. Shouldn't the loop stop when cURL has finished fetching the file? Or am I just being silly; is the loop just restarting constantly?
<?php
$Resource = curl_init();
curl_setopt($Resource, CURLOPT_URL, '...');
curl_setopt($Resource, CURLOPT_HEADER, 0);
curl_setopt($Resource, CURLOPT_USERAGENT, '...');
while(curl_exec($Resource)){
break;
}
curl_close($Resource);
?>
I tried setting the CURLOPT_CONNECTTIMEOUT_MS / CURLOPT_CONNECTTIMEOUT options to very small values, but it didn't help in this case.
Is there a more "proper" way of doing this?

Answer 1

This statement is superflous:
while(curl_exec($Resource)){
break;
}
Instead just keep the return value for future reference:
$result = curl_exec($Resource);
The while loop does not help anything. So now to your question: You can tell curl that it should only take some bytes from the body and then quit. That can be achieved by reducing the CURLOPT_BUFFERSIZE to a small value and by using a callback function to tell curl it should stop:
$withCallback = array(
CURLOPT_BUFFERSIZE => 20, # ~ value of bytes you'd like to get
CURLOPT_WRITEFUNCTION => function($handle, $data) {
echo "WRITE: (", strlen($data), ") $data\n";
return 0;
},
);
$handle = curl_init("http://stackoverflow.com/");
curl_setopt_array($handle, $withCallback);
curl_exec($handle);
curl_close($handle);
Output:
WRITE: (10) <!DOCTYPE
Another alternative is to make a HEAD request by using CURLOPT_NOBODY which will never fetch the body. But it's not a GET request.
The connect timeout settings are about how long it will take until the connect times out. The connect is the phase until the server accepts input from curl and curl starts to know about that the server does. It's not related to the phase when curl fetches data from the server, that's
CURLOPT_TIMEOUT The maximum number of seconds to allow cURL functions to execute.
You find a long list of available options in the PHP Manual: curl_setopt­Docs.

Answer 2

Perhaps that might be helpful?
$GLOBALS["dataread"] = 0;
define("MAX_DATA", 3000); // how many bytes should be read?
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://www.php.net/");
curl_setopt($ch, CURLOPT_WRITEFUNCTION, "handlewrite");
curl_exec($ch);
curl_close($ch);
function handlewrite($ch, $data)
{
$GLOBALS["dataread"] += strlen($data);
echo "READ " . strlen($data) . " bytes\n";
if ($GLOBALS["dataread"] > MAX_DATA) {
return 0;
}
return strlen($data);
}