When a browser makes a request to a php script, the browser sends some http headers which can look like this :
Host: localhost Connection: keep-alive User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.121 Safari/535.2 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: UTF-8,*;q=0.5 Cookie: username=admin; password=21232ffc3; PHPSESSID=o5m4e2td1m66c4pkjdag9vs0u2
The php script under request , may want to access these http headers. PHP has a method getallheaders() which provides these headers. So the code should be like this :
foreach (getallheaders() as $name => $value)
{
echo "$name: $valuen";
}
and the output should be like this :
Host: localhost Connection: keep-alive User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.121 Safari/535.2 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: UTF-8,*;q=0.5 Cookie: username=admin; password=21232ffc3; PHPSESSID=o5m4e2td1m66c4pkjdag9vs0u2
However the method getallheaders is available only when PHP is running as a Apache Module which is the Apache2handler.
When PHP is being run via CGI , this method would be unavailable. Calling it would give a :
Fatal error: Call to undefined function getallheaders()
In this case a workaround can be used which is as follows :
/**
The following function gets the http headers of a client request
when php is running as CGI
*/
if(!function_exists('getallheaders'))
{
function getallheaders()
{
foreach($_SERVER as $name => $value)
{
if(substr($name, 0, 5) == 'HTTP_')
{
$headers[str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($name, 5)))))] = $value;
}
}
return $headers;
}
}
The above method provides the http headers by fetching them from the $_SERVER variable, since they are present in the server variables in the form :
[HTTP_ACCEPT] => text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 [HTTP_ACCEPT_CHARSET] => UTF-8,*;q=0.5 [HTTP_ACCEPT_ENCODING] => gzip,deflate,sdch [HTTP_ACCEPT_LANGUAGE] => en-US,en;q=0.8 [HTTP_CACHE_CONTROL] => max-age=0 [HTTP_CONNECTION] => keep-alive [HTTP_COOKIE] => __utmz=179618234.1309856897.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __utma=179618234.703966342.1309856897.1309856897.1309856897.1 [HTTP_HOST] => www.yoursite.com [HTTP_USER_AGENT] => Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/534.30 (KHTML, like Gecko) Ubuntu/11.04 Chromium/12.0.742.112 Chrome/12.0.742.112 Safari/534.30
The documentation mentions that the method would be available in FastCGI from php 5.4
Another method called apache_request_headers() gives the same results :
foreach (apache_request_headers() as $name => $value)
{
echo "$name: $valuen";
}
Host: localhost Connection: keep-alive Cache-Control: max-age=0 User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.121 Safari/535.2 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Encoding: gzip,deflate,sdch Accept-Language: en-US,en;q=0.8 Accept-Charset: UTF-8,*;q=0.5 Cookie: username=admin; password=21232f297a57a5801fc3; PHPSESSID=o5m4e2td1m66c4pkjdag9vs0u2
This method is also unavailable in CGI mode and is available in FastCGI from php 5.4
