How can I emulate a get request exactly like a web browser?

Question

There are websites that when I open specific ajax request on browser, I get the resulted page. But when I try to load them with curl, I receive an error from the server.

How can I properly emulate a get request to the server that will simulate a browser?

That is what I am doing:

$url="https://new.aol.com/productsweb/subflows/ScreenNameFlow/AjaxSNAction.do?s=username&f=firstname&l=lastname"; ini_set('user_agent', 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.0.3705; .NET CLR 1.1.4322)'); $ch = curl_init();  curl_setopt($ch, CURLOPT_URL,$url); $result=curl_exec($ch); print $result; 

Answer 1

Are you sure the curl module honors ini_set('user_agent',...)? There is an option CURLOPT_USERAGENT described at http://docs.php.net/function.curl-setopt.
Could there also be a cookie tested by the server? That you can handle by using CURLOPT_COOKIE, CURLOPT_COOKIEFILE and/or CURLOPT_COOKIEJAR.

edit: Since the request uses https there might also be error in verifying the certificate, see CURLOPT_SSL_VERIFYPEER.

$url="https://new.aol.com/productsweb/subflows/ScreenNameFlow/AjaxSNAction.do?s=username&f=firstname&l=lastname"; $agent= 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.0.3705; .NET CLR 1.1.4322)';  $ch = curl_init(); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); curl_setopt($ch, CURLOPT_VERBOSE, true); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_USERAGENT, $agent); curl_setopt($ch, CURLOPT_URL,$url); $result=curl_exec($ch); var_dump($result); 

Answer 2

i'll make an example, first decide what browser you want to emulate, in this case i chose Firefox 60.6.1esr (64-bit), and check what GET request it issues, this can be obtained with a simple netcat server (MacOS bundles netcat, most linux distributions bunles netcat, and Windows users can get netcat from.. Cygwin.org , among other places),

setting up the netcat server to listen on port 9999: nc -l 9999

now hitting http://127.0.0.1:9999 in firefox, i get:

$ nc -l 9999 GET / HTTP/1.1 Host: 127.0.0.1:9999 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Connection: keep-alive Upgrade-Insecure-Requests: 1 

now let us compare that with this simple script:

<?php $ch=curl_init("http://127.0.0.1:9999"); curl_exec($ch); 

i get:

$ nc -l 9999 GET / HTTP/1.1 Host: 127.0.0.1:9999 Accept: */* 

there are several missing headers here, they can all be added with the CURLOPT_HTTPHEADER option of curl_setopt, but the User-Agent specifically should be set with CURLOPT_USERAGENT instead (it will be persistent across multiple calls to curl_exec() and if you use CURLOPT_FOLLOWLOCATION then it will persist across http redirections as well), and the Accept-Encoding header should be set with CURLOPT_ENCODING instead (if they're set with CURLOPT_ENCODING then curl will automatically decompress the response if the server choose to compress it, but if you set it via CURLOPT_HTTPHEADER then you must manually detect and decompress the content yourself, which is a pain in the ass and completely unnecessary, generally speaking) so adding those we get:

<?php $ch=curl_init("http://127.0.0.1:9999"); curl_setopt_array($ch,array(         CURLOPT_USERAGENT=>'Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0',         CURLOPT_ENCODING=>'gzip, deflate',         CURLOPT_HTTPHEADER=>array(                 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',                 'Accept-Language: en-US,en;q=0.5',                 'Connection: keep-alive',                 'Upgrade-Insecure-Requests: 1',         ), )); curl_exec($ch); 

now running that code, our netcat server gets:

$ nc -l 9999 GET / HTTP/1.1 Host: 127.0.0.1:9999 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0 Accept-Encoding: gzip, deflate Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Connection: keep-alive Upgrade-Insecure-Requests: 1 

and voila! our php-emulated browser GET request should now be indistinguishable from the real firefox GET request :)

this next part is just nitpicking, but if you look very closely, you'll see that the headers are stacked in the wrong order, firefox put the Accept-Encoding header in line 6, and our emulated GET request puts it in line 3.. to fix this, we can manually put the Accept-Encoding header in the right line,

<?php $ch=curl_init("http://127.0.0.1:9999"); curl_setopt_array($ch,array(         CURLOPT_USERAGENT=>'Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0',         CURLOPT_ENCODING=>'gzip, deflate',         CURLOPT_HTTPHEADER=>array(                 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',                 'Accept-Language: en-US,en;q=0.5',                 'Accept-Encoding: gzip, deflate',                 'Connection: keep-alive',                 'Upgrade-Insecure-Requests: 1',         ), )); curl_exec($ch); 

running that, our netcat server gets:

$ nc -l 9999 GET / HTTP/1.1 Host: 127.0.0.1:9999 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Connection: keep-alive Upgrade-Insecure-Requests: 1 

problem solved, now the headers is even in the correct order, and the request seems to be COMPLETELY INDISTINGUISHABLE from the real firefox request :) (i don't actually recommend this last step, it's a maintenance burden to keep CURLOPT_ENCODING in sync with the custom Accept-Encoding header, and i've never experienced a situation where the order of the headers are significant)