How do I read any request header in PHP
$_SERVER['HTTP_X_REQUESTED_WITH']
RFC3875, 4.1.18:
Meta-variables with names beginning with
HTTP_
contain values read from the client request header fields, if the protocol used is HTTP. The HTTP header field name is converted to upper case, has all occurrences of-
replaced with_
and hasHTTP_
prepended to give the meta-variable name.
You should find all HTTP headers in the $_SERVER
global variable prefixed with HTTP_
uppercased and with dashes (-) replaced by underscores (_).
For instance your X-Requested-With
can be found in:
$_SERVER['HTTP_X_REQUESTED_WITH']
It might be convenient to create an associative array from the $_SERVER
variable. This can be done in several styles, but here's a function that outputs camelcased keys:
$headers = array();
foreach ($_SERVER as $key => $value) {
if (strpos($key, 'HTTP_') === 0) {
$headers[str_replace(' ', '', ucwords(str_replace('_', ' ', strtolower(substr($key, 5)))))] = $value;
}
}
Now just use $headers['XRequestedWith']
to retrieve the desired header.
PHP manual on $_SERVER
: http://php.net/manual/en/reserved.variables.server.php
Since PHP 5.4.0 you can use getallheaders
function which returns all request headers as an associative array:
var_dump(getallheaders());
// array(8) {
// ["Accept"]=>
// string(63) "text/html[...]"
// ["Accept-Charset"]=>
// string(31) "ISSO-8859-1[...]"
// ["Accept-Encoding"]=>
// string(17) "gzip,deflate,sdch"
// ["Accept-Language"]=>
// string(14) "en-US,en;q=0.8"
// ["Cache-Control"]=>
// string(9) "max-age=0"
// ["Connection"]=>
// string(10) "keep-alive"
// ["Host"]=>
// string(9) "localhost"
// ["User-Agent"]=>
// string(108) "Mozilla/5.0 (Windows NT 6.1; WOW64) [...]"
// }
Earlier this function worked only when PHP was running as an Apache/NSAPI module.
IF: you only need a single header, instead of all headers, the quickest method is:
<?php
// Replace XXXXXX_XXXX with the name of the header you need in UPPERCASE (and with '-' replaced by '_')
$headerStringValue = $_SERVER['HTTP_XXXXXX_XXXX'];
ELSE IF: you run PHP as an Apache module or, as of PHP 5.4, using FastCGI (simple method):
apache_request_headers()
<?php
$headers = apache_request_headers();
foreach ($headers as $header => $value) {
echo "$header: $value <br />\n";
}
ELSE: In any other case, you can use (userland implementation):
<?php
function getRequestHeaders() {
$headers = array();
foreach($_SERVER as $key => $value) {
if (substr($key, 0, 5) <> 'HTTP_') {
continue;
}
$header = str_replace(' ', '-', ucwords(str_replace('_', ' ', strtolower(substr($key, 5)))));
$headers[$header] = $value;
}
return $headers;
}
$headers = getRequestHeaders();
foreach ($headers as $header => $value) {
echo "$header: $value <br />\n";
}
See Also:
getallheaders() - (PHP >= 5.4) cross platform edition Alias of apache_request_headers()
apache_response_headers() - Fetch all HTTP response headers.
headers_list() - Fetch a list of headers to be sent.