PHP程序使用socket通过SMTP发送邮件

看上图，用smtp发送邮件的过程：

1、连接服务器，返回220

2、发送命令HELO sendmail，返回250，是向服务器标识自己，标识符可以自定义，这里是sendmail。

3、发送命令AUTH LOGIN，返回334，要求认证。之后发送base64编码之后的用户名，服务器返回334，再发送base64编码后的密码，服务器返回235。

4、登录成功之后，发送命令MAIL FROM:，服务器返回250，邮件发送者。

5、发送命令RCPT TO:，服务器返回250，邮件接收者。

6、发送命令DATA，服务器返回354，之后可以发送邮件内容了，邮件内容用\r\n.\r\n结束，就是换行.换行，结束发送之后，服务器返回250.

7、发送命令QUIT，返回221，服务器连接关闭。

在代码里面，没发送一条命令，用\r\n结束输入。

/**
* 邮件发送类
* 支持发送纯文本邮件和HTML格式的邮件
* @example
* $config = array(
*               "from" => "*****",
*               "to" => "***",
*               "subject" => "test",
*               "body" => "test",
*               "username" => "***",
*               "password" => "****",
*               "isHTML" => true
*       );
*
* $mail = new MySendMail();
*
* $mail->setServer("smtp.126.com");
*
* $mail->setMailInfo($config);
* if(!$mail->sendMail()) {
*       echo $mail->error();
*       return 1;
* }
*/
class MySendMail {
        /**
        * @var 邮件传输代理用户名
        * @access private
        */
        private $_userName;
        /**
        * @var 邮件传输代理密码
        * @access private
        */
        private $_password;
        /**
        * @var 邮件传输代理服务器地址
        * @access protected
        */
        protected $_sendServer;
        /**
        * @var 邮件传输代理服务器端口
        * @access protected
        */
        protected $_port=25;
        /**
        * @var 发件人
        * @access protected
        */
        protected $_from;
        /**
        * @var 收件人
        * @access protected
        */
        protected $_to;
        /**
        * @var 主题
        * @access protected
        */
        protected $_subject;
        /**
        * @var 邮件正文
        * @access protected
        */
        protected $_body;
        /**
        * @var 是否是HTML格式的邮件
        * @access protected
        */
        protected $_isHTML=false;
        /**
        * @var socket资源
        * @access protected
        */
        protected $_socket;
        /**
        * @var 错误信息
        * @access protected
        */
        protected $_errorMessage;
        public function __construct($from="", $to="", $subject="", $body="", $server="", $username="", $password="",$isHTML="", $port="") {
                if(!empty($from)){
                        $this->_from = $from;
                }
                if(!empty($to)){
                        $this->_to = $to;
                }
                if(!empty($subject)){
                        $this->_subject = $subject;
                }
                if(!empty($body)){
                        $this->_body = $body;
                }
                if(!empty($isHTML)){
                        $this->_isHTML = $isHTML;
                }
                if(!empty($server)){
                        $this->_sendServer = $server;
                }
                if(!empty($port)){
                        $this->_port = $port;
                }
                if(!empty($username)){
                        $this->_userName = $username;
                }
                if(!empty($password)){
                        $this->_password = $password;
                }
        }
        /**
        * 设置邮件传输代理
        * @param string $server 代理服务器的ip或者域名
        * @param int $port 代理服务器的端口，smtp默认25号端口
        * @param int $localPort 本地端口
        * @return boolean
        */
        public function setServer($server, $port=25) {
                if(!isset($server) || empty($server) || !is_string($server)) {
                        $this->_errorMessage = "first one is an invalid parameter";
                        return false;
                }
                if(!is_numeric($port)){
                        $this->_errorMessage = "first two is an invalid parameter";
                        return false;
                }
                $this->_sendServer = $server;
                $this->_port = $port;
                return true;
        }
        /**
        * 设置邮件
        * @access public
        * @param array $config 邮件配置信息
        * 包含邮件发送人、接收人、主题、内容、邮件传输代理的验证信息
        * @return boolean
        */
        public function setMailInfo($config) {
                if(!is_array($config) || count($config) < 6){
                        $this->_errorMessage = "parameters are required";
                        return false;
                }
                $this->_from = $config['from'];
                $this->_to = $config['to'];
                $this->_subject = $config['subject'];
                $this->_body = $config['body'];
                $this->_userName = $config['username'];
                $this->_password = $config['password'];
                if(isset($config['isHTML'])){
                        $this->_isHTML = $config['isHTML'];
                }
                return true;
        }
        /**
        * 发送邮件
        * @access public
        * @return boolean
        */
        public function sendMail() {
                $command = $this->getCommand();
                $this->socket();
                foreach ($command as $value) {
                        if($this->sendCommand($value[0], $value[1])) {
                                continue;
                        }
                        else{
                                return false;
                        }
                }
                $this->close(); //其实这里也没必要关闭，smtp命令：QUIT发出之后，服务器就关闭了连接，本地的socket资源会自动释放
                echo 'Mail OK!';
                return true;
        }
        /**
        * 返回错误信息
        * @return string
        */
        public function error(){
                if(!isset($this->_errorMessage)) {
                        $this->_errorMessage = "";
                }
                return $this->_errorMessage;
        }
        /**
        * 返回mail命令
        * @access protected
        * @return array
        */
        protected function getCommand() {
                if($this->_isHTML) {
                        $mail = "MIME-Version:1.0\r\n";
                        $mail .= "Content-type:text/html;charset=utf-8\r\n";
                        $mail .= "FROM:test<" . $this->_from . ">\r\n";
                        $mail .= "TO:<" . $this->_to . ">\r\n";
                        $mail .= "Subject:" . $this->_subject ."\r\n\r\n";
                        $mail .= $this->_body . "\r\n.\r\n";
                }
                else{
                        $mail = "FROM:test<" . $this->_from . ">\r\n";
                        $mail .= "TO:<" . $this->_to . ">\r\n";
                        $mail .= "Subject:" . $this->_subject ."\r\n\r\n";
                        $mail .= $this->_body . "\r\n.\r\n";
                }
                $command = array(
                                array("HELO sendmail\r\n", 250),
                                array("AUTH LOGIN\r\n", 334),
                                array(base64_encode($this->_userName) . "\r\n", 334),
                                array(base64_encode($this->_password) . "\r\n", 235),
                                array("MAIL FROM:<" . $this->_from . ">\r\n", 250),
                                array("RCPT TO:<" . $this->_to . ">\r\n", 250),
                                array("DATA\r\n", 354),
                                array($mail, 250),
                                array("QUIT\r\n", 221)
                );
                return $command;
        }
        /**
        * @access protected
        * @param string $command 发送到服务器的smtp命令
        * @param int $code 期望服务器返回的响应吗
        * @param boolean
        */
        protected function sendCommand($command, $code) {
                echo 'Send command:' . $command . ',expected code:' . $code . '';
                //发送命令给服务器
                try{
                        if(socket_write($this->_socket, $command, strlen($command))){
                                //读取服务器返回
                                $data = trim(socket_read($this->_socket, 1024));
                                echo 'response:' . $data . '';
                                if($data) {
                                        $pattern = "/^".$code."/";
                                        if(preg_match($pattern, $data)) {
                                                return true;
                                        }
                                        else{
                                                $this->_errorMessage = "Error:" . $data . "|**| command:";
                                                return false;
                                        }
                                }
                                else{
                                        $this->_errorMessage = "Error:" . socket_strerror(socket_last_error());
                                        return false;
                                }
                        }
                        else{
                                $this->_errorMessage = "Error:" . socket_strerror(socket_last_error());
                                return false;
                        }
                }catch(Exception $e) {
                        $this->_errorMessage = "Error:" . $e->getMessage();
                }
        }
        /**
        * 建立到服务器的网络连接
        * @access private
        * @return boolean
        */
        private function socket() {
                if(!function_exists("socket_create")) {
                        $this->_errorMessage = "extension php-sockets must be enabled";
                        return false;
                }
                //创建socket资源
                $this->_socket = socket_create(AF_INET, SOCK_STREAM, getprotobyname('tcp'));
                if(!$this->_socket) {
                        $this->_errorMessage = socket_strerror(socket_last_error());
                        return false;
                }
                //连接服务器
                if(!socket_connect($this->_socket, $this->_sendServer, $this->_port)) {
                        $this->_errorMessage = socket_strerror(socket_last_error());
                        return false;
                }
                socket_read($this->_socket, 1024);
                return true;
        }
        /**
        * 关闭socket
        * @access private
        * @return boolean
        */
        private function close() {
                if(isset($this->_socket) && is_object($this->_socket)) {
                        $this->_socket->close();
                        return true;
                }
                $this->_errorMessage = "no resource can to be close";
                return false;
        }
}
/**************************** Test ***********************************/
$config = array(
                "from" => "XXXXX",
                "to" => "XXXXX",
                "subject" => "test",
                "body" => "test",
                "username" => "XXXXX",
                "password" => "******",
                //"isHTML" => true
        );
$mail = new MySendMail();
$mail->setServer("smtp.126.com");
$mail->setMailInfo($config);
if(!$mail->sendMail()) {
        echo $mail->error();
        return 1;
}