digi-sendzi/lib/smtp.js

import { connect } from 'tls';  // For SSL and STARTTLS
import { Socket } from 'net';   // For non-encrypted connections (before STARTTLS)

class SMTPClient {
    constructor(host, port = 587, auth) {
        this.host = host;
        this.port = port;
        this.auth = auth;
        this.socket = null;
    }

    connect() {
        return new Promise((resolve, reject) => {
            if (this.port === 465) {
                // SSL connection (SMTPS)
                this.socket = connect({ host: this.host, port: this.port, rejectUnauthorized: false }, () => {
                    console.log(`Connected to SMTP server with SSL at ${this.host}:${this.port}`);
                    resolve();
                });
            } else if (this.port === 587) {
                // Non-encrypted connection, STARTTLS will be applied later
                this.socket = new Socket();
                this.socket.connect(this.port, this.host, () => {
                    console.log(`Connected to SMTP server at ${this.host}:${this.port}`);
                    resolve();
                });
            } else {
                // Plain non-encrypted connection (used for ports like 2525)
                this.socket = new Socket();
                this.socket.connect(this.port, this.host, () => {
                    console.log(`Connected to SMTP server at ${this.host}:${this.port} (No SSL/TLS)`);
                    resolve();
                });
            }

            this.socket.on('error', (err) => {
                reject(err);
            });
        });
    }

    async sendEmail(from, to, subject, body) {
        try {
            if (this.port === 587) {
                // If using STARTTLS
                await this.sendCommand(`EHLO ${this.host}`);
                await this.sendCommand(`STARTTLS`);
                this.upgradeToTLS();  // Upgrade connection to TLS after STARTTLS
            }

            await this.sendCommand(`EHLO ${this.host}`);  // Send EHLO again after STARTTLS or for SSL
            await this.sendCommand(`AUTH LOGIN`);
            await this.sendAuth();
            await this.sendCommand(`MAIL FROM:<${from}>`);
            await this.sendCommand(`RCPT TO:<${to}>`);
            await this.sendCommand('DATA');
            await this.sendCommand(`${body}\r\n.`);
            await this.sendCommand('QUIT');
        } catch (error) {
            throw new Error(`Error sending email: ${error.message}`);
        }
    }

    async sendAuth() {
        const base64User = Buffer.from(this.auth.user).toString('base64');
        const base64Pass = Buffer.from(this.auth.pass).toString('base64');
        await this.sendCommand(base64User);
        return await this.sendCommand(base64Pass);
    }

    sendCommand(command) {
        return new Promise((resolve, reject) => {
            this.socket.write(`${command}\r\n`, (err) => {
                if (err) return reject(err);

                this.socket.once('data', (data) => {
                    const response = data.toString();
                    console.log('SMTP Response:', response);

                    if (response.startsWith('250') || response.startsWith('354') || response.startsWith('235')) {
                        resolve(response);
                    } else if (response.startsWith('334')) {
                        resolve();  // Continue authentication
                    } else if (response.startsWith('221')) {
                        console.log('SMTP session closed successfully.');
                        resolve(response);
                    } else if (response.startsWith('220')) {
                        resolve();  // Initial greeting
                    } else {
                        console.error('SMTP Error:', response);
                        reject(new Error(`SMTP Error: ${response}`));
                    }
                });
            });
        });
    }

    // Upgrade the current connection to TLS (STARTTLS mode)
    upgradeToTLS() {
        this.socket = connect({
            socket: this.socket,  // Upgrade the existing socket to TLS
            rejectUnauthorized: false
        }, () => {
            console.log(`Connection upgraded to TLS`);
        });
    }
}

export default SMTPClient;