Detect curl useragent in php

Question

I'm using this script to detect curl in a php page but it doesen't work... I always get "curl ua"

if ($usera = "curl")
   echo "curl ua";
else 
   echo "no curl";

?>

Answer 1

The exact curl user-agent string will be different based on version. For example this one:

curl/7.15.1 (i386-pc-win32) libcurl/7.15.1 OpenSSL/0.9.8a zlib/1.2.3

So what you can do is, check whether the curl or libcurl is existed in the agent string or not.

if(preg_match("/curl|libcurl/", $usera)){
    // do something ...
}

But if the curl client change the Agent String, then you'll not be able to detect it. For example with below curl request I am changing the user agent into Opera 9.0

curl -A "Opera 9.0" http://www.example.com/

Answer 2

The Useragent could be changed by user, but default settings could be recognized by:

function is_curl() {
    if (stristr($_SERVER["HTTP_USER_AGENT"], 'curl'))
        return true;
}