<?php
/*
    EmailValidator - a PHP class for validation e-mail addresses.
    Copyright (C) 2012 Bogdan 'bogdro' Drozdowski, bogdandr <at> op . pl

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see http://www.gnu.org/licenses/.
*/

	class EmailValidator
	{
		const EV_VALID = 0;
		const EV_INVALID = 1;
		const EV_UNKNOWN = 2;

		private $server_response;

		public function get_server_response ()
		{
			return $this->server_response;
		}

		public static function get_status_as_string ($res)
		{
			if ( $res == EmailValidator::EV_VALID ) return 'Valid';
			else if ( $res == EmailValidator::EV_INVALID ) return 'Invalid';
			else return 'Unknown';
		}

		public function validate ($address, $our_address = 'root@localhost', $our_domain = 'localhost')
		{
			$parts = explode ('@', $address);
			$mx = array ();
			if ( getmxrr ($parts[1], &$mx) === true )
			{
				foreach ($mx as $weigth => $host )
				{
					$v = $this->validate1 ($address, $our_address, $our_domain, $host);
					if ( $v == EmailValidator::EV_VALID
						|| $v == EmailValidator::EV_INVALID )
					{
						return $v;
					}
					// continue when status unknown
				}
			}
			else
			{
				// use the hostname if no MX records available
				return $this->validate1 ($address, $our_address, $our_domain, $parts[1]);
			}
			return EmailValidator::EV_UNKNOWN;
		}

		private function validate1 ($address, $our_address, $our_domain, $host)
		{
			$this->server_response = '';
			$sock = socket_create (AF_INET, SOCK_STREAM, SOL_TCP);
			if ( $sock === false ) return EmailValidator::EV_UNKNOWN;
			if ( socket_connect ($sock, $host, 25) === false )
			{
				socket_close ($sock);
				return EmailValidator::EV_UNKNOWN;
			}

			$buf = '';
			socket_recv ($sock, &$buf, 1000, 0);
			if ( $buf[0] != '2' )
			{
				socket_close ($sock);
				$this->server_response = $buf;
				return EmailValidator::EV_UNKNOWN;
			}
			$buf = "EHLO $our_domain\r\n";
			socket_send ($sock, $buf, strlen ($buf), 0);

			$buf = '';
			socket_recv ($sock, &$buf, 1000, 0);
			if ( $buf[0] != '2' )
			{
				$buf = "HELO $our_domain\r\n";
				socket_send ($sock, $buf, strlen ($buf), 0);

				$buf = '';
				socket_recv ($sock, &$buf, 1000, 0);
				if ( $buf[0] != '2' )
				{
					socket_close ($sock);
					$this->server_response = $buf;
					return EmailValidator::EV_UNKNOWN;
				}
			}
			$buf = "MAIL FROM:<$our_address>\r\n";
			socket_send ($sock, $buf, strlen ($buf), 0);

			$buf = '';
			socket_recv ($sock, &$buf, 1000, 0);
			if ( $buf[0] != '2' )
			{
				socket_close ($sock);
				$this->server_response = $buf;
				return EmailValidator::EV_UNKNOWN;
			}
			$buf = "RCPT TO:<$address>\r\n";
			socket_send ($sock, $buf, strlen ($buf), 0);

			$buf = '';
			socket_recv ($sock, &$buf, 1000, 0);
			socket_close ($sock);

			$this->server_response = $buf;
			if ( $buf[0] == '2' ) return EmailValidator::EV_VALID;
			else if ( $buf[0] == '5' ) return EmailValidator::EV_INVALID;
			return EmailValidator::EV_UNKNOWN;
		}
	}
?>