ImapAuthenticateWithApachePhpScript

<?php
/*
Nginx sends headers as
Auth-User: somuser
Auth-Pass: somepass
On my php app server these are seen as
HTTP_AUTH_USER and HTTP_AUTH_PASS
*/
if (!isset($_SERVER["HTTP_AUTH_USER"] ) || !isset($_SERVER["HTTP_AUTH_PASS"] )){
  fail();
}
$username=$_SERVER["HTTP_AUTH_USER"] ;
$userpass=$_SERVER["HTTP_AUTH_PASS"] ;
$protocol=$_SERVER["HTTP_AUTH_PROTOCOL"] ;
// default backend port
$backend_port=110;
if ($protocol=="imap") {
  $backend_port=143;
}
if ($protocol=="smtp") {
  $backend_port=25;
}
// nginx likes ip address so if your
// application gives back hostname, convert it to ip address here
$backend_ip["mailhost01"] ="192.168.1.22";
$backend_ip["mailhost02"] ="192.168.1.33";
// Authenticate the user or fail
if (!authuser($username,$userpass)){
  fail();
  exit;
}
// Get the server for this user if we have reached so far
$userserver=getmailserver($username);
// Get the ip address of the server
// We are assuming that you backend returns hostname
// We try to get the ip else return what we got back
$server_ip=(isset($backend_ip[$userserver]))?$backend_ip[$userserver] :$userserver;
// Pass!
pass($server_ip, $backend_port);
 
//END
 
 
function authuser($user,$pass){
  // put your logic here to authen the user to any backend
  // you want (datbase, ldap, etc)
  // for example, we will just return true;
  return true;
}
 
function getmailserver($user){
  // put the logic here to get the mailserver
  // backend for the user. You can get this from
  // some database or ldap etc
  // dummy logic, all users that start with a,c,f and g get mailhost01
  // the others get mailhost02
  if in_array(substr($user,0,1), array("a", "c", "f", "g")){
    return "mailhost01";
  } else {
    return "mailhost02";
  }
}
 
function fail(){
  header("Auth-Status: Invalid login or password");
  exit;
}
 
function pass($server,$port){
  header("Auth-Status: OK");
  header("Auth-Server: $server");
  header("Auth-Port: $port");
  exit;
}