use our own serverHost call so that ownCloud works with reverse proxy servers

apps/files_sharing/ajax/email.php

 $subject = $user.' shared a '.$type.' with you';
 $link = $_POST['link'];
 $text = $user.' shared the '.$type.' '.$_POST['file'].' with you. It is available for download here: '.$link;
-$fromaddress = OCP\Config::getUserValue($user, 'settings', 'email', 'sharing-noreply@'.$_SERVER['HTTP_HOST']);
+$fromaddress = OCP\Config::getUserValue($user, 'settings', 'email', 'sharing-noreply@'.OCP\Util::getServerHost());
 OC_Mail::send($_POST['toaddress'], $_POST['toaddress'], $subject, $text, $fromaddress, $user);
 
-?>
+?>

apps/user_openid/phpmyid.php

 //Determine the requested URL - DO NOT OVERRIDE
 $profile['req_url'] = sprintf("%s://%s%s",
 		      $proto,
-		      $_SERVER['HTTP_HOST'],
+		      OCP\Util::getServerHost(),
 // 		      $port,//host  already includes the path
 		      $_SERVER["REQUEST_URI"]);
 

apps/user_openid/user_openid.php

 		// Get identity from user and redirect browser to OpenID Server
 		$openid = new SimpleOpenID;
 		$openid->SetIdentity($uid);
-		$openid->SetTrustRoot('http://' . $_SERVER["HTTP_HOST"]);
+		$openid->SetTrustRoot('http://' . OCP\Util::getServerHost());
 		if ($openid->GetOpenIDServer()){
-			$openid->SetApprovedURL('http://' . $_SERVER["HTTP_HOST"] . OC::$WEBROOT);      // Send Response from OpenID server to this script
+			$openid->SetApprovedURL('http://' . OCP\Util::getServerHost() . OC::$WEBROOT);      // Send Response from OpenID server to this script
 			$openid->Redirect();     // This will redirect user to OpenID Server
 			exit;
 		}else{

core/lostpassword/index.php

 			$tmpl->assign('link', $link);
 			$msg = $tmpl->fetchPage();
 			$l = OC_L10N::get('core');
-			$from = 'lostpassword-noreply@' . $_SERVER['HTTP_HOST'];
+			$from = 'lostpassword-noreply@' . OCP\Util::getServerHost();
 			$r=mail($email, $l->t('Owncloud password reset'), $msg, 'From:' . $from);
 			OC_MAIL::send($email,$_POST['user'],$l->t('ownCloud password reset'),$msg,$from,'ownCloud');
 			echo('sent');

lib/ocs.php

    */
   private static function apiConfig($format) {
     $user=OC_OCS::checkpassword(false);
-    $url=substr($_SERVER['HTTP_HOST'].$_SERVER['SCRIPT_NAME'],0,-11).'';
+    $url=substr(OCP\Util::getServerHost().$_SERVER['SCRIPT_NAME'],0,-11).'';
 
     $xml['version']='1.5';
     $xml['website']='ownCloud';
-    $xml['host']=$_SERVER['HTTP_HOST'];
+    $xml['host']=OCP\Util::getServerHost();
     $xml['contact']='';
     $xml['ssl']='false';
     echo(OC_OCS::generatexml($format,'ok',100,'',$xml,'config','',1));

ocs/providers.php

 
 require_once('../lib/base.php');
 
-$url='http://'.substr($_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'],0,-17).'ocs/v1.php/';
+$url='http://'.substr(OCP\Util::getServerHost().$_SERVER['REQUEST_URI'],0,-17).'ocs/v1.php/';
 
 echo('
 <providers>