endpoint for update check

contrib/updatecheck/calcversions.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+version=`head -n 1 VERSION`
+revision=`git describe --always`
+echo "ebusd=${version}.${revision}"
+#TODO add calculation for config files

contrib/updatecheck/index.php

@@ -0,0 +1,39 @@
+<?php
+$agent = $_SERVER['HTTP_USER_AGENT'];
+if (substr($agent, 0, 5)==='ebusd') {
+  $t = time();
+  $a = $_SERVER["REMOTE_ADDR"];
+  $r = @file_get_contents('php://input');
+  $v = @file_get_contents('versions.txt');
+  $versions = array();
+  if ($v) {
+    $v = explode("\n", $v);
+    $func = function($val, $k) {
+      global $versions;
+      $val = explode('=', $val);
+      if (count($val)>1) {
+        $versions[$val[0]] = explode(',', $val[1]);
+      }
+    };
+    array_walk($v, $func);
+  }
+  header('Content-Type: text/plain');
+  $ret = 'unknown';
+  $r = @json_decode($r, true);
+  if (!$r || !isset($r['v'])) {
+    $ret = 'invalid request';
+  } else {
+    if (isset($versions['ebusd'])) {
+      if ($r['v']==$versions['ebusd'][0]) {
+        $ret = 'OK';
+      } else {
+        $ret = 'ebusd '.$versions['ebusd'][0].' available';
+      }
+    }
+    // TODO add check for config files
+  }
+  echo $ret;
+  exit;
+}
+header('HTTP/1.1 404 Not Found');
+?>