346 lines
11 KiB
TypeScript
346 lines
11 KiB
TypeScript
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/**
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* SMTP TLS Handler
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* Responsible for handling TLS-related SMTP functionality
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*/
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import * as plugins from '../../../plugins.ts';
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import type { ITlsHandler, ISmtpServer, ISmtpSession } from './interfaces.ts';
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import { SmtpResponseCode, SecurityEventType, SecurityLogLevel } from './constants.ts';
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import { SmtpLogger } from './utils/logging.ts';
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import { getSocketDetails, getTlsDetails } from './utils/helpers.ts';
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import {
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loadCertificatesFromString,
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generateSelfSignedCertificates,
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createTlsOptions,
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type ICertificateData
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} from './certificate-utils.ts';
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import { SmtpState } from '../interfaces.ts';
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/**
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* Handles TLS functionality for SMTP server
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*/
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export class TlsHandler implements ITlsHandler {
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/**
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* Reference to the SMTP server instance
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*/
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private smtpServer: ISmtpServer;
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/**
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* Certificate data
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*/
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private certificates: ICertificateData;
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/**
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* TLS options
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*/
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private options: plugins.tls.TlsOptions;
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/**
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* Creates a new TLS handler
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* @param smtpServer - SMTP server instance
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*/
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constructor(smtpServer: ISmtpServer) {
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this.smtpServer = smtpServer;
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// Initialize certificates
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const serverOptions = this.smtpServer.getOptions();
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try {
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// Try to load certificates from provided options
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this.certificates = loadCertificatesFromString({
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key: serverOptions.key,
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cert: serverOptions.cert,
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ca: serverOptions.ca
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});
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SmtpLogger.info('Successfully loaded TLS certificates');
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} catch (error) {
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SmtpLogger.warn(`Failed to load certificates from options, using self-signed: ${error instanceof Error ? error.message : String(error)}`);
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// Fall back to self-signed certificates for testing
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this.certificates = generateSelfSignedCertificates();
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}
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// Initialize TLS options
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this.options = createTlsOptions(this.certificates);
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}
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/**
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* Handle STARTTLS command
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* @param socket - Client socket
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*/
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public async handleStartTls(socket: plugins.net.Socket, session: ISmtpSession): Promise<plugins.tls.TLSSocket | null> {
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// Check if already using TLS
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if (session.useTLS) {
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this.sendResponse(socket, `${SmtpResponseCode.BAD_SEQUENCE} TLS already active`);
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return null;
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}
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// Check if we have the necessary TLS certificates
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if (!this.isTlsEnabled()) {
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this.sendResponse(socket, `${SmtpResponseCode.TLS_UNAVAILABLE_TEMP} TLS not available`);
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return null;
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}
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// Send ready for TLS response
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this.sendResponse(socket, `${SmtpResponseCode.SERVICE_READY} Ready to start TLS`);
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// Upgrade the connection to TLS
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try {
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const tlsSocket = await this.startTLS(socket);
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return tlsSocket;
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} catch (error) {
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SmtpLogger.error(`STARTTLS negotiation failed: ${error instanceof Error ? error.message : String(error)}`, {
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sessionId: session.id,
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remoteAddress: session.remoteAddress,
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error: error instanceof Error ? error : new Error(String(error))
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});
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// Log security event
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SmtpLogger.logSecurityEvent(
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SecurityLogLevel.ERROR,
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SecurityEventType.TLS_NEGOTIATION,
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'STARTTLS negotiation failed',
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{ error: error instanceof Error ? error.message : String(error) },
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session.remoteAddress
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);
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return null;
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}
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}
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/**
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* Upgrade a connection to TLS
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* @param socket - Client socket
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*/
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public async startTLS(socket: plugins.net.Socket): Promise<plugins.tls.TLSSocket> {
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// Get the session for this socket
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const session = this.smtpServer.getSessionManager().getSession(socket);
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try {
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// Import the enhanced STARTTLS handler
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// This uses a more robust approach to TLS upgrades
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const { performStartTLS } = await import('./starttls-handler.ts');
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SmtpLogger.info('Using enhanced STARTTLS implementation');
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// Use the enhanced STARTTLS handler with better error handling and socket management
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const serverOptions = this.smtpServer.getOptions();
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const tlsSocket = await performStartTLS(socket, {
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key: serverOptions.key,
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cert: serverOptions.cert,
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ca: serverOptions.ca,
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session: session,
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sessionManager: this.smtpServer.getSessionManager(),
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connectionManager: this.smtpServer.getConnectionManager(),
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// Callback for successful upgrade
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onSuccess: (secureSocket) => {
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SmtpLogger.info('TLS connection successfully established via enhanced STARTTLS', {
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remoteAddress: secureSocket.remoteAddress,
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remotePort: secureSocket.remotePort,
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protocol: secureSocket.getProtocol() || 'unknown',
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cipher: secureSocket.getCipher()?.name || 'unknown'
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});
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// Log security event
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SmtpLogger.logSecurityEvent(
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SecurityLogLevel.INFO,
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SecurityEventType.TLS_NEGOTIATION,
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'STARTTLS successful with enhanced implementation',
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{
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protocol: secureSocket.getProtocol(),
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cipher: secureSocket.getCipher()?.name
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},
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secureSocket.remoteAddress,
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undefined,
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true
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);
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},
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// Callback for failed upgrade
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onFailure: (error) => {
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SmtpLogger.error(`Enhanced STARTTLS failed: ${error.message}`, {
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sessionId: session?.id,
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remoteAddress: socket.remoteAddress,
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error
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});
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// Log security event
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SmtpLogger.logSecurityEvent(
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SecurityLogLevel.ERROR,
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SecurityEventType.TLS_NEGOTIATION,
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'Enhanced STARTTLS failed',
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{ error: error.message },
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socket.remoteAddress,
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undefined,
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false
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);
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},
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// Function to update session state
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updateSessionState: this.smtpServer.getSessionManager().updateSessionState?.bind(this.smtpServer.getSessionManager())
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});
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// If STARTTLS failed with the enhanced implementation, log the error
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if (!tlsSocket) {
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SmtpLogger.warn('Enhanced STARTTLS implementation failed to create TLS socket', {
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sessionId: session?.id,
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remoteAddress: socket.remoteAddress
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});
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throw new Error('Failed to create TLS socket');
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}
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return tlsSocket;
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} catch (error) {
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// Log STARTTLS failure
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SmtpLogger.error(`Failed to upgrade connection to TLS: ${error instanceof Error ? error.message : String(error)}`, {
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remoteAddress: socket.remoteAddress,
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remotePort: socket.remotePort,
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error: error instanceof Error ? error : new Error(String(error)),
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stack: error instanceof Error ? error.stack : 'No stack trace available'
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});
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// Log security event
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SmtpLogger.logSecurityEvent(
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SecurityLogLevel.ERROR,
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SecurityEventType.TLS_NEGOTIATION,
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'Failed to upgrade connection to TLS',
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{
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error: error instanceof Error ? error.message : String(error),
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stack: error instanceof Error ? error.stack : 'No stack trace available'
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},
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socket.remoteAddress,
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undefined,
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false
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);
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// Destroy the socket on error
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socket.destroy();
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throw error;
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}
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}
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/**
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* Create a secure server
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* @returns TLS server instance or undefined if TLS is not enabled
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*/
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public createSecureServer(): plugins.tls.Server | undefined {
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if (!this.isTlsEnabled()) {
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return undefined;
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}
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try {
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SmtpLogger.info('Creating secure TLS server');
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// Log certificate info
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SmtpLogger.debug('Using certificates for secure server', {
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keyLength: this.certificates.key.length,
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certLength: this.certificates.cert.length,
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caLength: this.certificates.ca ? this.certificates.ca.length : 0
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});
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// Create TLS options using our certificate utilities
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// This ensures proper PEM format handling and protocol negotiation
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const tlsOptions = createTlsOptions(this.certificates, true); // Use server options
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SmtpLogger.info('Creating TLS server with options', {
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minVersion: tlsOptions.minVersion,
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maxVersion: tlsOptions.maxVersion,
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handshakeTimeout: tlsOptions.handshakeTimeout
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});
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// Create a server with wider TLS compatibility
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const server = new plugins.tls.Server(tlsOptions);
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// Add error handling
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server.on('error', (err) => {
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SmtpLogger.error(`TLS server error: ${err.message}`, {
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error: err,
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stack: err.stack
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});
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});
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// Log TLS details for each connection
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server.on('secureConnection', (socket) => {
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SmtpLogger.info('New secure connection established', {
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protocol: socket.getProtocol(),
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cipher: socket.getCipher()?.name,
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remoteAddress: socket.remoteAddress,
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remotePort: socket.remotePort
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});
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});
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return server;
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} catch (error) {
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SmtpLogger.error(`Failed to create secure server: ${error instanceof Error ? error.message : String(error)}`, {
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error: error instanceof Error ? error : new Error(String(error)),
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stack: error instanceof Error ? error.stack : 'No stack trace available'
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});
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return undefined;
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}
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}
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/**
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* Check if TLS is enabled
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* @returns Whether TLS is enabled
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*/
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public isTlsEnabled(): boolean {
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const options = this.smtpServer.getOptions();
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return !!(options.key && options.cert);
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}
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/**
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* Send a response to the client
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* @param socket - Client socket
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* @param response - Response message
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*/
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private sendResponse(socket: plugins.net.Socket | plugins.tls.TLSSocket, response: string): void {
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// Check if socket is still writable before attempting to write
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if (socket.destroyed || socket.readyState !== 'open' || !socket.writable) {
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SmtpLogger.debug(`Skipping response to closed/destroyed socket: ${response}`, {
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remoteAddress: socket.remoteAddress,
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remotePort: socket.remotePort,
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destroyed: socket.destroyed,
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readyState: socket.readyState,
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writable: socket.writable
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});
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return;
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}
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try {
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socket.write(`${response}\r\n`);
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SmtpLogger.logResponse(response, socket);
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} catch (error) {
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SmtpLogger.error(`Error sending response: ${error instanceof Error ? error.message : String(error)}`, {
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response,
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remoteAddress: socket.remoteAddress,
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remotePort: socket.remotePort,
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error: error instanceof Error ? error : new Error(String(error))
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});
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socket.destroy();
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}
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}
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/**
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* Check if TLS is available (interface requirement)
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*/
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public isTlsAvailable(): boolean {
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return this.isTlsEnabled();
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}
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/**
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* Get TLS options (interface requirement)
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*/
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public getTlsOptions(): plugins.tls.TlsOptions {
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return this.options;
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}
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/**
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* Clean up resources
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*/
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public destroy(): void {
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// Clear any cached certificates or TLS contexts
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// TlsHandler doesn't have timers but may have cached resources
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SmtpLogger.debug('TlsHandler destroyed');
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}
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}
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