Simple rainloop plugin to login to the webmail using oidc server, dovecot master password and apache module auth_openidc - Download those files in a directory named oidc-master-password-login/

index.php

<?php

// Copyright 2020 Nicolas Mora <mail@babelouest.org>
// License MIT
// There's room for improvement

class ExternalHeaderLoginPlugin extends \RainLoop\Plugins\AbstractPlugin
{
	public function Init()
	{
		$this->addHook('filter.login-credentials', 'OverrideLoginСredentials');
		$this->addHook('filter.app-data', 'FilterAppData');
	}

	public function configMapping()
	{
		return array(
			\RainLoop\Plugins\Property::NewInstance('header_username')->SetLabel('Header Username')
				->SetType(\RainLoop\Enumerations\PluginPropertyType::STRING_TEXT)
				->SetDescription('Header key containing the username')
				->SetDefaultValue("OIDC_CLAIM_userid"),
			\RainLoop\Plugins\Property::NewInstance('master_username')->SetLabel('Master Username and separator')
				->SetType(\RainLoop\Enumerations\PluginPropertyType::STRING_TEXT)
				->SetDescription('IMAP Master username and separator')
				->SetDefaultValue("*masteruser"),
			\RainLoop\Plugins\Property::NewInstance('master_password')->SetLabel('Master Password')
				->SetType(\RainLoop\Enumerations\PluginPropertyType::PASSWORD)
				->SetDescription('IMAP Master password')
				->SetDefaultValue("password"),
		);
	}

	public function FilterAppData($bAdmin, &$aResult)
	{
		if (!$bAdmin && \is_array($aResult) && isset($aResult['Auth']) && !$aResult['Auth'])
		{
			$aResult['DevEmail'] = $_SERVER[$this->Config()->Get('plugin', 'header_username', '')];
			$aResult['DevPassword'] = APP_DUMMY;
		}
	}
	
	public function OverrideLoginСredentials(&$sEmail, &$sLogin, &$sPassword)
	{
		$sLogin = $_SERVER[$this->Config()->Get('plugin', 'header_username', '')].$this->Config()->Get('plugin', 'master_username', '');
		$sPassword = $this->Config()->Get('plugin', 'master_password', '');
	}
}

VERSION

1.0

See https://github.com/babelouest/glewlwyd/blob/master/docs/GETTING_STARTED.md#use-case-connect-webmail-rainloop-with-openid-connect-plugin-using-dovecot-configured-with-a-master-password for a full documentation

Due to rainloop lack of activity, I don't recommend to use this plugin anymore