/*
 * VeyonAuthHelper.cpp - main file for Veyon Authentication Helper
 *
 * Copyright (c) 2010-2019 Tobias Junghans <tobydox@veyon.io>
 *
 * This file is part of Veyon - https://veyon.io
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program (see COPYING); if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 */

#include <QDataStream>
#include <QFile>

#include <security/pam_appl.h>

static QByteArray pam_username;
static QByteArray pam_password;
static QByteArray pam_service;

static int pam_conv( int num_msg, const struct pam_message** msg, struct pam_response** resp, void * )
{
	auto reply = reinterpret_cast<pam_response *>(
				malloc( sizeof(struct pam_response) * static_cast<size_t>( num_msg ) ) );
	if( reply == nullptr )
	{
		return PAM_CONV_ERR;
	}

	for( int replies = 0; replies < num_msg; ++replies )
	{
		switch( msg[replies]->msg_style )
		{
			case PAM_PROMPT_ECHO_ON:
				reply[replies].resp_retcode = PAM_SUCCESS;
				reply[replies].resp = strdup( pam_username.constData() );
				break;
			case PAM_PROMPT_ECHO_OFF:
				reply[replies].resp_retcode = PAM_SUCCESS;
				reply[replies].resp = strdup( pam_password.constData() );
				break;
			case PAM_TEXT_INFO:
			case PAM_ERROR_MSG:
				reply[replies].resp_retcode = PAM_SUCCESS;
				reply[replies].resp = nullptr;
				break;
			default:
				free( reply );
				return PAM_CONV_ERR;
		}
	}

	*resp = reply;
	return PAM_SUCCESS;
}


int main()
{
	QByteArray username, password, service;
	QFile stdIn;
	stdIn.open( 0, QFile::ReadOnly | QFile::Unbuffered );
	QDataStream ds( &stdIn );
	ds >> pam_username;
	ds >> pam_password;
	ds >> pam_service;

	if( pam_service.isEmpty() )
	{
		pam_service = QByteArrayLiteral("login");
	}

	struct pam_conv pconv = { &pam_conv, nullptr };
	pam_handle_t* pamh = nullptr;
	auto err = pam_start( pam_service.constData(), nullptr, &pconv, &pamh );
	if( err == PAM_SUCCESS )
	{
		err = pam_authenticate( pamh, PAM_SILENT );
		if( err != PAM_SUCCESS )
		{
			printf( "pam_authenticate: %s\n", pam_strerror( pamh, err ) );
		}
	}
	else
	{
		printf( "pam_start: %s\n", pam_strerror( pamh, err ) );
	}

	pam_end( pamh, err );

	return err == PAM_SUCCESS ? 0 : -1;
}
