apache_request_headers drop-in function for PHP as FPM

apache_request_headers.php

<?php
// Drop-in replacement for apache_request_headers() when it's not available

if ( ! function_exists( 'apache_request_headers' ) ) {
	function apache_request_headers() {
		static $arrHttpHeaders;
		if ( ! $arrHttpHeaders ) {

			// Based on: http://www.iana.org/assignments/message-headers/message-headers.xml#perm-headers
			$arrCasedHeaders = array(
				// HTTP
				'Dasl'             => 'DASL',
				'Dav'              => 'DAV',
				'Etag'             => 'ETag',
				'Mime-Version'     => 'MIME-Version',
				'Slug'             => 'SLUG',
				'Te'               => 'TE',
				'Www-Authenticate' => 'WWW-Authenticate',
				// MIME
				'Content-Md5'      => 'Content-MD5',
				'Content-Id'       => 'Content-ID',
				'Content-Features' => 'Content-features',
			);
			$arrHttpHeaders  = array();

			foreach ( $_SERVER as $strKey => $mixValue ) {
				if ( 'HTTP_' !== substr( $strKey, 0, 5 ) ) {
					continue;
				}

				$strHeaderKey = strtolower( substr( $strKey, 5 ) );

				if ( 0 < substr_count( $strHeaderKey, '_' ) ) {
					$arrHeaderKey = explode( '_', $strHeaderKey );
					$arrHeaderKey = array_map( 'ucfirst', $arrHeaderKey );
					$strHeaderKey = implode( '-', $arrHeaderKey );
				} else {
					$strHeaderKey = ucfirst( $strHeaderKey );
				}

				if ( array_key_exists( $strHeaderKey, $arrCasedHeaders ) ) {
					$strHeaderKey = $arrCasedHeaders[ $strHeaderKey ];
				}

				$arrHttpHeaders[ $strHeaderKey ] = $mixValue;
			}

			/** in case you need authorization and your hosting provider has not fixed this for you:
			 * VHOST-Config:
			 * FastCgiExternalServer line needs    -pass-header Authorization
			 *
			 * .htaccess or VHOST-config file needs:
			 * SetEnvIf Authorization "(.*)" HTTP_AUTHORIZATION=$1
			 * to add the Authorization header to the environment for further processing
			 */
			if ( ! empty( $arrHttpHeaders['Authorization'] ) ) {
				// in case of Authorization, but the values not propagated properly, do so :)
				if ( ! isset( $_SERVER['PHP_AUTH_USER'] ) ) {
					list( $_SERVER['PHP_AUTH_USER'], $_SERVER['PHP_AUTH_PW'] ) = explode( ':', base64_decode( substr( $_SERVER['HTTP_AUTHORIZATION'], 6 ) ) );
				}
			}
		}

		return $arrHttpHeaders;
	}

	// execute now so other scripts have little chance to taint the information in $_SERVER
	// the data is cached, so multiple retrievals of the headers will not cause further impact on performance.
	apache_request_headers();
}

@rmpel - Thanks a lot. I refactored the code as suggested above. The authorization string is passed with api call and compared with token to allow API access. The code was breaking and fixed it. now its working. I really appreciate your help. Thanks again.