nsapi_request_headers() gets all the HTTP headers in the current request. This is only supported when PHP runs as a NSAPI module.
Note: Prior to PHP 4.3.3, getallheaders() was only available for the Apache servers. After PHP 4.3.3, getallheaders() is an alias for nsapi_request_headers() if you use the NSAPI module.
Note: You can also get at the value of the common CGI variables by reading them from the $_SERVER superglobal, which works whether or not you are using PHP as a NSAPI module.