4.1.16

changelog.md

@@ -1,5 +1,106 @@
 # Changelog
 
+## 2025-03-17 - 4.1.16 - fix(tls)
+Improve TLS alert handling in connection handler: use the new TlsAlert class to send proper unrecognized_name alerts when a ClientHello is missing SNI and wait for a retry on the same connection before closing. Also, add alertFallbackTimeout tracking to connection records for better timeout management.
+
+- Replaced hardcoded alert buffers in ConnectionHandler with calls to the TlsAlert class.
+- Removed old warnings and implemented a mechanism to remove existing 'data' listeners and await a new ClientHello.
+- Introduced alertFallbackTimeout property in connection records to track fallback timeout and ensure proper cleanup.
+- Extended the delay before closing the connection after sending an alert, providing the client more time to retry.
+
+## 2025-03-17 - 4.1.15 - fix(connectionhandler)
+Delay socket termination in TLS session resumption handling to allow proper alert processing
+
+- Removed the immediate socket.end() call in finishConnection and moved it inside the setTimeout, ensuring that clients (especially Chrome) have additional time to process the TLS alert before connection termination
+- This prevents premature socket closure on ClientHello without SNI when session tickets are disallowed
+
+## 2025-03-17 - 4.1.14 - fix(ConnectionHandler)
+Use the correct TLS alert data and increase the delay before socket termination when session resumption without SNI is detected.
+
+- Replaced certificateExpiredAlert with serverNameUnknownAlertData for sending the appropriate alert.
+- Increased the cleanup delay from 1000ms to 5000ms to allow a more graceful termination.
+
+## 2025-03-17 - 4.1.13 - fix(tls-handshake)
+Set certificate_expired TLS alert level to warning instead of fatal to allow graceful termination.
+
+- In the TLS handshake alert for certificate_expired (0x2F), changed the alert level from 0x02 (fatal) to 0x01 (warning).
+- This change avoids abrupt connection termination, enabling a smoother handling of certificate expiration alerts.
+
+## 2025-03-17 - 4.1.12 - fix(classes.pp.connectionhandler)
+Replace unrecognized_name alert data with certificate_expired alert in TLS handshake handling for session resumption without SNI
+
+- Switched the alert payload from serverNameUnknownAlertData to a new certificateExpiredAlert buffer
+- Now sends a fatal certificate_expired alert (code 47) instead of a warning unrecognized_name alert
+- Improves TLS error reporting and encourages immediate disconnection when a ClientHello lacks SNI and session tickets are disallowed
+
+## 2025-03-17 - 4.1.11 - fix(connectionhandler)
+Increase delay before cleaning up connections when session resumption is blocked due to missing SNI, allowing more natural socket termination.
+
+- Changed cleanup delay in ts/classes.pp.connectionhandler.ts from 300ms to 1000ms.
+- This fix ensures that sockets get sufficient time to terminate gracefully.
+
+## 2025-03-16 - 4.1.10 - fix(connectionhandler)
+Increase delay timings for TLS alert transmission in session ticket blocking to allow graceful socket termination
+
+- Updated finishConnection: replaced immediate socket.destroy with a graceful end call
+- Increased delay after successful write from 50ms to 200ms to allow alert processing
+- Raised safety timeout from 250ms to 400ms when waiting for 'drain' event
+
+## 2025-03-16 - 4.1.9 - fix(ConnectionHandler)
+Replace closeNotify alert with handshake failure alert in TLS ClientHello handling to properly signal missing SNI and enforce session ticket restrictions.
+
+- Switched alert data sent on missing SNI from closeNotifyAlert to sslHandshakeFailureAlertData.
+- Ensures consistent TLS alert behavior during handshake failure.
+
+## 2025-03-16 - 4.1.8 - fix(ConnectionHandler/tls)
+Change the TLS alert sent when a ClientHello lacks SNI: use the close_notify alert instead of handshake_failure to prompt immediate retry with SNI.
+
+- Replaced the previously sent handshake_failure alert (code 0x28) with a close_notify alert (code 0x00) in the TLS session resumption handling in ConnectionHandler.
+- This change encourages clients to immediately retry and include SNI when allowSessionTicket is false.
+
+## 2025-03-16 - 4.1.7 - fix(classes.pp.connectionhandler)
+Improve TLS alert handling in ClientHello when SNI is missing and session tickets are disallowed
+
+- Replace the unrecognized_name alert with a handshake_failure alert to ensure better client behavior.
+- Refactor the alert sending mechanism using cork/uncork and add a safety timeout for the drain event.
+- Enhance logging for debugging TLS handshake failures when SNI is absent.
+
+## 2025-03-16 - 4.1.6 - fix(tls)
+Refine TLS ClientHello handling when allowSessionTicket is false by replacing extensive alert timeout logic with a concise warning alert and short delay, encouraging immediate client retry with proper SNI
+
+- Update the TLS alert sending mechanism to use cork/uncork and a short, fixed delay instead of long timeouts
+- Remove redundant event listeners and excessive cleanup logic after sending the alert
+- Improve code clarity and encourage clients (e.g., Chrome) to retry handshake with SNI more responsively
+
+## 2025-03-16 - 4.1.5 - fix(TLS/ConnectionHandler)
+Improve handling of TLS session resumption without SNI by sending an 'unrecognized_name' alert instead of immediately terminating the connection. This change adds a grace period for the client to retry the handshake with proper SNI and cleans up the connection if no valid response is received.
+
+- Send a TLS warning (unrecognized_name alert, code 112) when a ClientHello is received without SNI and session tickets are disallowed.
+- Utilize socket cork/uncork to ensure the alert is sent as a single packet.
+- Add a 5-second alert timeout and a subsequent 30-second grace period to allow clients to initiate a new handshake with SNI.
+- Clean up and terminate the connection if no valid SNI is provided after the grace period, logging appropriate termination reasons.
+
+## 2025-03-15 - 4.1.4 - fix(ConnectionHandler)
+Refactor ConnectionHandler code formatting for improved readability and consistency in log messages and whitespace handling
+
+- Standardized indentation and spacing in method signatures and log statements
+- Aligned inline comments and string concatenations for clarity
+- Minor refactoring of parameter formatting without changing functionality
+
+## 2025-03-15 - 4.1.3 - fix(connectionhandler)
+Improve handling of TLS ClientHello messages when allowSessionTicket is disabled and no SNI is provided by sending a warning alert (unrecognized_name, code 0x70) with a proper callback and delay to ensure the alert is transmitted before closing the connection.
+
+- Replace the fatal alert (0x02/0x40) with a warning alert (0x01/0x70) to notify clients to send SNI.
+- Use socket.write callback to wait 100ms after sending the alert before terminating the connection.
+- Remove the previous short (50ms) delay in favor of a more reliable delay mechanism before cleanup.
+
+## 2025-03-15 - 4.1.2 - fix(connectionhandler)
+Send proper TLS alert before terminating connections when SNI is missing and session tickets are disallowed.
+
+- Added logic to transmit a fatal TLS alert (Handshake Failure) before closing the connection when no SNI is present with allowSessionTicket=false.
+- Introduced a slight 50ms delay after sending the alert to ensure the client receives the alert properly.
+- Applied these changes both for the initial ClientHello and when handling subsequent TLS data.
+
 ## 2025-03-15 - 4.1.1 - fix(tls)
 Enforce strict SNI handling in TLS connections by terminating ClientHello messages lacking SNI when session tickets are disallowed and removing legacy session cache code.
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@push.rocks/smartproxy",
-  "version": "4.1.1",
+  "version": "4.1.16",
   "private": false,
   "description": "A powerful proxy package that effectively handles high traffic, with features such as SSL/TLS support, port proxying, WebSocket handling, dynamic routing with authentication options, and automatic ACME certificate management.",
   "main": "dist_ts/index.js",

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartproxy',
-  version: '4.1.1',
+  version: '4.1.16',
   description: 'A powerful proxy package that effectively handles high traffic, with features such as SSL/TLS support, port proxying, WebSocket handling, dynamic routing with authentication options, and automatic ACME certificate management.'
 }

ts/classes.pp.connectionhandler.ts

@@ -1,5 +1,9 @@
 import * as plugins from './plugins.js';
-import type { IConnectionRecord, IDomainConfig, IPortProxySettings } from './classes.pp.interfaces.js';
+import type {
+  IConnectionRecord,
+  IDomainConfig,
+  IPortProxySettings,
+} from './classes.pp.interfaces.js';
 import { ConnectionManager } from './classes.pp.connectionmanager.js';
 import { SecurityManager } from './classes.pp.securitymanager.js';
 import { DomainConfigManager } from './classes.pp.domainconfigmanager.js';
@@ -7,6 +11,7 @@ import { TlsManager } from './classes.pp.tlsmanager.js';
 import { NetworkProxyBridge } from './classes.pp.networkproxybridge.js';
 import { TimeoutManager } from './classes.pp.timeoutmanager.js';
 import { PortRangeManager } from './classes.pp.portrangemanager.js';
+import { TlsAlert } from './classes.pp.tlsalert.js';
 
 /**
  * Handles new connection processing and setup logic
@@ -73,8 +78,8 @@ export class ConnectionHandler {
     if (this.settings.enableDetailedLogging) {
       console.log(
         `[${connectionId}] New connection from ${remoteIP} on port ${localPort}. ` +
-        `Keep-Alive: ${record.hasKeepAlive ? 'Enabled' : 'Disabled'}. ` +
-        `Active connections: ${this.connectionManager.getConnectionCount()}`
+          `Keep-Alive: ${record.hasKeepAlive ? 'Enabled' : 'Disabled'}. ` +
+          `Active connections: ${this.connectionManager.getConnectionCount()}`
       );
     } else {
       console.log(
@@ -94,7 +99,10 @@ export class ConnectionHandler {
   /**
    * Handle a connection that should be forwarded to NetworkProxy
    */
-  private handleNetworkProxyConnection(socket: plugins.net.Socket, record: IConnectionRecord): void {
+  private handleNetworkProxyConnection(
+    socket: plugins.net.Socket,
+    record: IConnectionRecord
+  ): void {
     const connectionId = record.id;
     let initialDataReceived = false;
 
@@ -104,7 +112,7 @@ export class ConnectionHandler {
         console.log(
           `[${connectionId}] Initial data warning (${this.settings.initialDataTimeout}ms) for connection from ${record.remoteIP}`
         );
-        
+
         // Add a grace period instead of immediate termination
         setTimeout(() => {
           if (!initialDataReceived) {
@@ -144,7 +152,7 @@ export class ConnectionHandler {
       if (!this.tlsManager.isTlsHandshake(chunk) && localPort === 443) {
         console.log(
           `[${connectionId}] Non-TLS connection detected on port 443. ` +
-          `Terminating connection - only TLS traffic is allowed on standard HTTPS port.`
+            `Terminating connection - only TLS traffic is allowed on standard HTTPS port.`
         );
         if (record.incomingTerminationReason === null) {
           record.incomingTerminationReason = 'non_tls_blocked';
@@ -159,8 +167,8 @@ export class ConnectionHandler {
       if (this.tlsManager.isTlsHandshake(chunk)) {
         record.isTLS = true;
 
-        // Check session tickets if they're disabled
-        if (this.settings.allowSessionTicket === false && this.tlsManager.isClientHello(chunk)) {
+        // Check for ClientHello to extract SNI - but don't enforce it for NetworkProxy
+        if (this.tlsManager.isClientHello(chunk)) {
           // Create connection info for SNI extraction
           const connInfo = {
             sourceIp: record.remoteIP,
@@ -169,49 +177,46 @@ export class ConnectionHandler {
             destPort: socket.localPort || 0,
           };
 
-          // Extract SNI for domain-specific NetworkProxy handling
+          // Extract SNI for domain-specific NetworkProxy handling if available
           const serverName = this.tlsManager.extractSNI(chunk, connInfo);
 
-          // If allowSessionTicket is false and we can't determine SNI, terminate the connection
-          if (!serverName) {
-            console.log(
-              `[${connectionId}] No SNI detected in ClientHello and allowSessionTicket=false. ` +
-              `Terminating connection to force new TLS handshake with SNI.`
-            );
-            if (record.incomingTerminationReason === null) {
-              record.incomingTerminationReason = 'session_ticket_blocked_no_sni';
-              this.connectionManager.incrementTerminationStat('incoming', 'session_ticket_blocked_no_sni');
-            }
-            socket.end();
-            this.connectionManager.cleanupConnection(record, 'session_ticket_blocked_no_sni');
-            return;
-          }
+          // For NetworkProxy connections, we'll allow session tickets even without SNI
+          // We'll only use the serverName if available to determine the specific NetworkProxy port
+          if (serverName) {
+            // Save domain config and SNI in connection record
+            const domainConfig = this.domainConfigManager.findDomainConfig(serverName);
+            record.domainConfig = domainConfig;
+            record.lockedDomain = serverName;
 
-          // Save domain config and SNI in connection record
-          const domainConfig = this.domainConfigManager.findDomainConfig(serverName);
-          record.domainConfig = domainConfig;
-          record.lockedDomain = serverName;
+            // Use domain-specific NetworkProxy port if configured
+            if (domainConfig && this.domainConfigManager.shouldUseNetworkProxy(domainConfig)) {
+              const networkProxyPort = this.domainConfigManager.getNetworkProxyPort(domainConfig);
 
-          // Use domain-specific NetworkProxy port if configured
-          if (domainConfig && this.domainConfigManager.shouldUseNetworkProxy(domainConfig)) {
-            const networkProxyPort = this.domainConfigManager.getNetworkProxyPort(domainConfig);
+              if (this.settings.enableDetailedLogging) {
+                console.log(
+                  `[${connectionId}] Using domain-specific NetworkProxy for ${serverName} on port ${networkProxyPort}`
+                );
+              }
 
-            if (this.settings.enableDetailedLogging) {
-              console.log(
-                `[${connectionId}] Using domain-specific NetworkProxy for ${serverName} on port ${networkProxyPort}`
+              // Forward to NetworkProxy with domain-specific port
+              this.networkProxyBridge.forwardToNetworkProxy(
+                connectionId,
+                socket,
+                record,
+                chunk,
+                networkProxyPort,
+                (reason) => this.connectionManager.initiateCleanupOnce(record, reason)
               );
+              return;
             }
-
-            // Forward to NetworkProxy with domain-specific port
-            this.networkProxyBridge.forwardToNetworkProxy(
-              connectionId,
-              socket,
-              record,
-              chunk,
-              networkProxyPort,
-              (reason) => this.connectionManager.initiateCleanupOnce(record, reason)
+          } else if (
+            this.settings.allowSessionTicket === false &&
+            this.settings.enableDetailedLogging
+          ) {
+            // Log that we're allowing a session resumption without SNI for NetworkProxy
+            console.log(
+              `[${connectionId}] Allowing session resumption without SNI for NetworkProxy forwarding`
             );
-            return;
           }
         }
 
@@ -226,14 +231,10 @@ export class ConnectionHandler {
         );
       } else {
         // If not TLS, use normal direct connection
-        console.log(`[${connectionId}] Non-TLS connection on NetworkProxy port ${record.localPort}`);
-        this.setupDirectConnection(
-          socket,
-          record,
-          undefined,
-          undefined,
-          chunk
+        console.log(
+          `[${connectionId}] Non-TLS connection on NetworkProxy port ${record.localPort}`
         );
+        this.setupDirectConnection(socket, record, undefined, undefined, chunk);
       }
     });
   }
@@ -266,7 +267,7 @@ export class ConnectionHandler {
           console.log(
             `[${connectionId}] Initial data warning (${this.settings.initialDataTimeout}ms) for connection from ${record.remoteIP}`
           );
-          
+
           // Add a grace period instead of immediate termination
           setTimeout(() => {
             if (!initialDataReceived) {
@@ -351,14 +352,13 @@ export class ConnectionHandler {
       record.domainConfig = domainConfig;
 
       // Check if this domain should use NetworkProxy (domain-specific setting)
-      if (domainConfig && 
-          this.domainConfigManager.shouldUseNetworkProxy(domainConfig) && 
-          this.networkProxyBridge.getNetworkProxy()) {
-        
+      if (
+        domainConfig &&
+        this.domainConfigManager.shouldUseNetworkProxy(domainConfig) &&
+        this.networkProxyBridge.getNetworkProxy()
+      ) {
         if (this.settings.enableDetailedLogging) {
-          console.log(
-            `[${connectionId}] Domain ${serverName} is configured to use NetworkProxy`
-          );
+          console.log(`[${connectionId}] Domain ${serverName} is configured to use NetworkProxy`);
         }
 
         const networkProxyPort = this.domainConfigManager.getNetworkProxyPort(domainConfig);
@@ -380,23 +380,24 @@ export class ConnectionHandler {
       // IP validation
       if (domainConfig) {
         const ipRules = this.domainConfigManager.getEffectiveIPRules(domainConfig);
-        
+
         // Skip IP validation if allowedIPs is empty
         if (
           domainConfig.allowedIPs.length > 0 &&
-          !this.securityManager.isIPAuthorized(record.remoteIP, ipRules.allowedIPs, ipRules.blockedIPs)
+          !this.securityManager.isIPAuthorized(
+            record.remoteIP,
+            ipRules.allowedIPs,
+            ipRules.blockedIPs
+          )
         ) {
           return rejectIncomingConnection(
             'rejected',
-            `Connection rejected: IP ${record.remoteIP} not allowed for domain ${domainConfig.domains.join(
-              ', '
-            )}`
+            `Connection rejected: IP ${
+              record.remoteIP
+            } not allowed for domain ${domainConfig.domains.join(', ')}`
           );
         }
-      } else if (
-        this.settings.defaultAllowedIPs &&
-        this.settings.defaultAllowedIPs.length > 0
-      ) {
+      } else if (this.settings.defaultAllowedIPs && this.settings.defaultAllowedIPs.length > 0) {
         if (
           !this.securityManager.isIPAuthorized(
             record.remoteIP,
@@ -463,28 +464,36 @@ export class ConnectionHandler {
       } else {
         // Attempt to find a matching forced domain config based on the local port.
         const forcedDomain = this.domainConfigManager.findDomainConfigForPort(localPort);
-        
+
         if (forcedDomain) {
           const ipRules = this.domainConfigManager.getEffectiveIPRules(forcedDomain);
-          
-          if (!this.securityManager.isIPAuthorized(record.remoteIP, ipRules.allowedIPs, ipRules.blockedIPs)) {
+
+          if (
+            !this.securityManager.isIPAuthorized(
+              record.remoteIP,
+              ipRules.allowedIPs,
+              ipRules.blockedIPs
+            )
+          ) {
             console.log(
-              `[${connectionId}] Connection from ${record.remoteIP} rejected: IP not allowed for domain ${forcedDomain.domains.join(
+              `[${connectionId}] Connection from ${
+                record.remoteIP
+              } rejected: IP not allowed for domain ${forcedDomain.domains.join(
                 ', '
               )} on port ${localPort}.`
             );
             socket.end();
             return;
           }
-          
+
           if (this.settings.enableDetailedLogging) {
             console.log(
-              `[${connectionId}] Port-based connection from ${record.remoteIP} on port ${localPort} matched domain ${forcedDomain.domains.join(
-                ', '
-              )}.`
+              `[${connectionId}] Port-based connection from ${
+                record.remoteIP
+              } on port ${localPort} matched domain ${forcedDomain.domains.join(', ')}.`
             );
           }
-          
+
           setupConnection('', undefined, forcedDomain, localPort);
           return;
         }
@@ -502,14 +511,14 @@ export class ConnectionHandler {
           clearTimeout(initialTimeout);
           initialTimeout = null;
         }
-        
+
         initialDataReceived = true;
-        
+
         // Block non-TLS connections on port 443
         if (!this.tlsManager.isTlsHandshake(chunk) && localPort === 443) {
           console.log(
             `[${connectionId}] Non-TLS connection detected on port 443 in SNI handler. ` +
-            `Terminating connection - only TLS traffic is allowed on standard HTTPS port.`
+              `Terminating connection - only TLS traffic is allowed on standard HTTPS port.`
           );
           if (record.incomingTerminationReason === null) {
             record.incomingTerminationReason = 'non_tls_blocked';
@@ -542,38 +551,144 @@ export class ConnectionHandler {
 
           // Extract SNI
           serverName = this.tlsManager.extractSNI(chunk, connInfo) || '';
-          
+
           // If allowSessionTicket is false and this is a ClientHello with no SNI, terminate the connection
-          if (this.settings.allowSessionTicket === false && 
-              this.tlsManager.isClientHello(chunk) && 
-              !serverName) {
-            
-            // Check if this is a session resumption
-            const resumptionInfo = this.tlsManager.handleSessionResumption(
-              chunk, 
-              connectionId,
-              false // No SNI
+          if (
+            this.settings.allowSessionTicket === false &&
+            this.tlsManager.isClientHello(chunk) &&
+            !serverName
+          ) {
+            // Block ClientHello without SNI when allowSessionTicket is false
+            console.log(
+              `[${connectionId}] No SNI detected in ClientHello and allowSessionTicket=false. ` +
+                `Sending unrecognized_name alert to encourage immediate retry with SNI on same connection.`
             );
-            
-            if (resumptionInfo.shouldBlock) {
+
+            try {
+              // Send the alert but do NOT end the connection
+              // Using our new TlsAlert class for better alert management
+              socket.cork();
+              socket.write(TlsAlert.alerts.unrecognizedName);
+              socket.uncork();
+
               console.log(
-                `[${connectionId}] Session resumption without SNI detected and allowSessionTicket=false. ` +
-                `Terminating connection to force new TLS handshake with SNI.`
+                `[${connectionId}] Alert sent, waiting for new ClientHello on same connection...`
               );
-              if (record.incomingTerminationReason === null) {
-                record.incomingTerminationReason = resumptionInfo.reason || 'session_ticket_blocked_no_sni';
-                this.connectionManager.incrementTerminationStat(
-                  'incoming', 
-                  resumptionInfo.reason || 'session_ticket_blocked_no_sni'
-                );
+
+              // Remove existing data listener and wait for a new ClientHello
+              socket.removeAllListeners('data');
+
+              // Set up a new data handler to capture the next message
+              socket.once('data', (retryChunk) => {
+                // Cancel the fallback timeout as we received data
+                if (record.alertFallbackTimeout) {
+                  clearTimeout(record.alertFallbackTimeout);
+                  record.alertFallbackTimeout = null;
+                }
+
+                // Check if this is a new ClientHello
+                if (this.tlsManager.isClientHello(retryChunk)) {
+                  console.log(`[${connectionId}] Received new ClientHello after alert`);
+
+                  // Extract SNI from the new ClientHello
+                  const newServerName = this.tlsManager.extractSNI(retryChunk, connInfo) || '';
+
+                  if (newServerName) {
+                    console.log(`[${connectionId}] New ClientHello contains SNI: ${newServerName}`);
+
+                    // Update the record with the new SNI
+                    record.lockedDomain = newServerName;
+
+                    // Continue with normal connection setup using the new chunk with SNI
+                    setupConnection(newServerName, retryChunk);
+                  } else {
+                    console.log(
+                      `[${connectionId}] New ClientHello still missing SNI, closing connection`
+                    );
+
+                    // If still no SNI after retry, now we can close the connection
+                    if (record.incomingTerminationReason === null) {
+                      record.incomingTerminationReason = 'session_ticket_blocked_no_sni';
+                      this.connectionManager.incrementTerminationStat(
+                        'incoming',
+                        'session_ticket_blocked_no_sni'
+                      );
+                    }
+
+                    // Send a close_notify alert before ending the connection
+                    TlsAlert.sendCloseNotify(socket)
+                      .catch((err) => {
+                        console.log(`[${connectionId}] Error sending close_notify: ${err.message}`);
+                      })
+                      .finally(() => {
+                        // Clean up even if sending the alert fails
+                        this.connectionManager.cleanupConnection(
+                          record,
+                          'session_ticket_blocked_no_sni'
+                        );
+                      });
+                  }
+                } else {
+                  console.log(
+                    `[${connectionId}] Received non-ClientHello data after alert, closing connection`
+                  );
+
+                  // If we got something other than a ClientHello, close the connection
+                  if (record.incomingTerminationReason === null) {
+                    record.incomingTerminationReason = 'invalid_protocol';
+                    this.connectionManager.incrementTerminationStat('incoming', 'invalid_protocol');
+                  }
+
+                  // Send a protocol_version alert before ending the connection
+                  TlsAlert.send(socket, TlsAlert.LEVEL_FATAL, TlsAlert.PROTOCOL_VERSION, true)
+                    .catch((err) => {
+                      console.log(
+                        `[${connectionId}] Error sending protocol_version alert: ${err.message}`
+                      );
+                    })
+                    .finally(() => {
+                      // Clean up even if sending the alert fails
+                      this.connectionManager.cleanupConnection(record, 'invalid_protocol');
+                    });
+                }
+              });
+
+              // Set a fallback timeout in case the client doesn't respond
+              const fallbackTimeout = setTimeout(() => {
+                console.log(`[${connectionId}] No response after alert, closing connection`);
+
+                if (record.incomingTerminationReason === null) {
+                  record.incomingTerminationReason = 'alert_timeout';
+                  this.connectionManager.incrementTerminationStat('incoming', 'alert_timeout');
+                }
+
+                // Send a close_notify alert before ending the connection
+                TlsAlert.sendCloseNotify(socket)
+                  .catch((err) => {
+                    console.log(`[${connectionId}] Error sending close_notify: ${err.message}`);
+                  })
+                  .finally(() => {
+                    // Clean up even if sending the alert fails
+                    this.connectionManager.cleanupConnection(record, 'alert_timeout');
+                  });
+              }, 10000); // 10 second timeout
+
+              // Make sure the timeout doesn't keep the process alive
+              if (fallbackTimeout.unref) {
+                fallbackTimeout.unref();
               }
+
+              // Store the timeout in the record so it can be cleared during cleanup
+              record.alertFallbackTimeout = fallbackTimeout;
+            } catch (err) {
+              // If we can't send the alert, fall back to immediate termination
+              console.log(`[${connectionId}] Error sending TLS alert: ${err.message}`);
               socket.end();
-              this.connectionManager.cleanupConnection(
-                record, 
-                resumptionInfo.reason || 'session_ticket_blocked_no_sni'
-              );
-              return;
+              this.connectionManager.cleanupConnection(record, 'session_ticket_blocked_no_sni');
             }
+
+            // Return early to prevent the normal flow
+            return;
           }
         }
 
@@ -621,23 +736,21 @@ export class ConnectionHandler {
     overridePort?: number
   ): void {
     const connectionId = record.id;
-    
+
     // Determine target host
-    const targetHost = domainConfig 
-      ? this.domainConfigManager.getTargetIP(domainConfig) 
+    const targetHost = domainConfig
+      ? this.domainConfigManager.getTargetIP(domainConfig)
       : this.settings.targetIP!;
-    
+
     // Determine target port
-    const targetPort = overridePort !== undefined 
-      ? overridePort 
-      : this.settings.toPort;
-    
+    const targetPort = overridePort !== undefined ? overridePort : this.settings.toPort;
+
     // Setup connection options
     const connectionOptions: plugins.net.NetConnectOpts = {
       host: targetHost,
       port: targetPort,
     };
-    
+
     // Preserve source IP if configured
     if (this.settings.preserveSourceIP) {
       connectionOptions.localAddress = record.remoteIP.replace('::ffff:', '');
@@ -894,18 +1007,20 @@ export class ConnectionHandler {
 
       // Process any remaining data in the queue before switching to piping
       processDataQueue();
-      
+
       // Set up piping immediately
       pipingEstablished = true;
-      
+
       // Flush all pending data to target
       if (record.pendingData.length > 0) {
         const combinedData = Buffer.concat(record.pendingData);
-        
+
         if (this.settings.enableDetailedLogging) {
-          console.log(`[${connectionId}] Forwarding ${combinedData.length} bytes of initial data to target`);
+          console.log(
+            `[${connectionId}] Forwarding ${combinedData.length} bytes of initial data to target`
+          );
         }
-        
+
         // Write pending data immediately
         targetSocket.write(combinedData, (err) => {
           if (err) {
@@ -913,19 +1028,19 @@ export class ConnectionHandler {
             return this.connectionManager.initiateCleanupOnce(record, 'write_error');
           }
         });
-        
+
         // Clear the buffer now that we've processed it
         record.pendingData = [];
         record.pendingDataSize = 0;
       }
-      
+
       // Setup piping in both directions without any delays
       socket.pipe(targetSocket);
       targetSocket.pipe(socket);
-      
+
       // Resume the socket to ensure data flows
       socket.resume();
-      
+
       // Process any data that might be queued in the interim
       if (dataQueue.length > 0) {
         // Write any remaining queued data directly to the target socket
@@ -936,7 +1051,7 @@ export class ConnectionHandler {
         dataQueue.length = 0;
         queueSize = 0;
       }
-      
+
       if (this.settings.enableDetailedLogging) {
         console.log(
           `[${connectionId}] Connection established: ${record.remoteIP} -> ${targetHost}:${connectionOptions.port}` +
@@ -1001,15 +1116,12 @@ export class ConnectionHandler {
       }
 
       // Set connection timeout
-      record.cleanupTimer = this.timeoutManager.setupConnectionTimeout(
-        record,
-        (record, reason) => {
-          console.log(
-            `[${connectionId}] Connection from ${record.remoteIP} exceeded max lifetime, forcing cleanup.`
-          );
-          this.connectionManager.initiateCleanupOnce(record, reason);
-        }
-      );
+      record.cleanupTimer = this.timeoutManager.setupConnectionTimeout(record, (record, reason) => {
+        console.log(
+          `[${connectionId}] Connection from ${record.remoteIP} exceeded max lifetime, forcing cleanup.`
+        );
+        this.connectionManager.initiateCleanupOnce(record, reason);
+      });
 
       // Mark TLS handshake as complete for TLS connections
       if (record.isTLS) {
@@ -1023,4 +1135,4 @@ export class ConnectionHandler {
       }
     });
   }
-}
+}

ts/classes.pp.interfaces.ts

@@ -104,6 +104,7 @@ export interface IConnectionRecord {
   lockedDomain?: string; // Used to lock this connection to the initial SNI
   connectionClosed: boolean; // Flag to prevent multiple cleanup attempts
   cleanupTimer?: NodeJS.Timeout; // Timer for max lifetime/inactivity
+  alertFallbackTimeout?: NodeJS.Timeout; // Timer for fallback after alert
   lastActivity: number; // Last activity timestamp for inactivity detection
   pendingData: Buffer[]; // Buffer to hold data during connection setup
   pendingDataSize: number; // Track total size of pending data

ts/classes.pp.tlsalert.ts

@@ -0,0 +1,218 @@
+import * as net from 'net';
+
+/**
+ * TlsAlert class for managing TLS alert messages
+ */
+export class TlsAlert {
+  // TLS Alert Levels
+  static readonly LEVEL_WARNING = 0x01;
+  static readonly LEVEL_FATAL = 0x02;
+  
+  // TLS Alert Description Codes - RFC 8446 (TLS 1.3) / RFC 5246 (TLS 1.2)
+  static readonly CLOSE_NOTIFY = 0x00;
+  static readonly UNEXPECTED_MESSAGE = 0x0A;
+  static readonly BAD_RECORD_MAC = 0x14;
+  static readonly DECRYPTION_FAILED = 0x15; // TLS 1.0 only
+  static readonly RECORD_OVERFLOW = 0x16;
+  static readonly DECOMPRESSION_FAILURE = 0x1E; // TLS 1.2 and below
+  static readonly HANDSHAKE_FAILURE = 0x28;
+  static readonly NO_CERTIFICATE = 0x29; // SSLv3 only
+  static readonly BAD_CERTIFICATE = 0x2A;
+  static readonly UNSUPPORTED_CERTIFICATE = 0x2B;
+  static readonly CERTIFICATE_REVOKED = 0x2C;
+  static readonly CERTIFICATE_EXPIRED = 0x2F;
+  static readonly CERTIFICATE_UNKNOWN = 0x30;
+  static readonly ILLEGAL_PARAMETER = 0x2F;
+  static readonly UNKNOWN_CA = 0x30;
+  static readonly ACCESS_DENIED = 0x31;
+  static readonly DECODE_ERROR = 0x32;
+  static readonly DECRYPT_ERROR = 0x33;
+  static readonly EXPORT_RESTRICTION = 0x3C; // TLS 1.0 only
+  static readonly PROTOCOL_VERSION = 0x46;
+  static readonly INSUFFICIENT_SECURITY = 0x47;
+  static readonly INTERNAL_ERROR = 0x50;
+  static readonly INAPPROPRIATE_FALLBACK = 0x56;
+  static readonly USER_CANCELED = 0x5A;
+  static readonly NO_RENEGOTIATION = 0x64; // TLS 1.2 and below
+  static readonly MISSING_EXTENSION = 0x6D; // TLS 1.3
+  static readonly UNSUPPORTED_EXTENSION = 0x6E; // TLS 1.3
+  static readonly CERTIFICATE_REQUIRED = 0x6F; // TLS 1.3
+  static readonly UNRECOGNIZED_NAME = 0x70;
+  static readonly BAD_CERTIFICATE_STATUS_RESPONSE = 0x71;
+  static readonly BAD_CERTIFICATE_HASH_VALUE = 0x72; // TLS 1.2 and below
+  static readonly UNKNOWN_PSK_IDENTITY = 0x73;
+  static readonly CERTIFICATE_REQUIRED_1_3 = 0x74; // TLS 1.3
+  static readonly NO_APPLICATION_PROTOCOL = 0x78;
+  
+  /**
+   * Create a TLS alert buffer with the specified level and description code
+   * 
+   * @param level Alert level (warning or fatal)
+   * @param description Alert description code
+   * @param tlsVersion TLS version bytes (default is TLS 1.2: 0x0303)
+   * @returns Buffer containing the TLS alert message
+   */
+  static create(
+    level: number,
+    description: number,
+    tlsVersion: [number, number] = [0x03, 0x03]
+  ): Buffer {
+    return Buffer.from([
+      0x15, // Alert record type
+      tlsVersion[0],
+      tlsVersion[1], // TLS version (default to TLS 1.2: 0x0303)
+      0x00,
+      0x02, // Length
+      level, // Alert level
+      description, // Alert description
+    ]);
+  }
+  
+  /**
+   * Create a warning-level TLS alert
+   * 
+   * @param description Alert description code
+   * @returns Buffer containing the warning-level TLS alert message
+   */
+  static createWarning(description: number): Buffer {
+    return this.create(this.LEVEL_WARNING, description);
+  }
+  
+  /**
+   * Create a fatal-level TLS alert
+   * 
+   * @param description Alert description code
+   * @returns Buffer containing the fatal-level TLS alert message
+   */
+  static createFatal(description: number): Buffer {
+    return this.create(this.LEVEL_FATAL, description);
+  }
+  
+  /**
+   * Send a TLS alert to a socket and optionally close the connection
+   * 
+   * @param socket The socket to send the alert to
+   * @param level Alert level (warning or fatal)
+   * @param description Alert description code
+   * @param closeAfterSend Whether to close the connection after sending the alert
+   * @param closeDelay Milliseconds to wait before closing the connection (default: 200ms)
+   * @returns Promise that resolves when the alert has been sent
+   */
+  static async send(
+    socket: net.Socket,
+    level: number,
+    description: number,
+    closeAfterSend: boolean = false,
+    closeDelay: number = 200
+  ): Promise<void> {
+    const alert = this.create(level, description);
+    
+    return new Promise<void>((resolve, reject) => {
+      try {
+        // Ensure the alert is written as a single packet
+        socket.cork();
+        const writeSuccessful = socket.write(alert, (err) => {
+          if (err) {
+            reject(err);
+            return;
+          }
+          
+          if (closeAfterSend) {
+            setTimeout(() => {
+              socket.end();
+              resolve();
+            }, closeDelay);
+          } else {
+            resolve();
+          }
+        });
+        socket.uncork();
+        
+        // If write wasn't successful immediately, wait for drain
+        if (!writeSuccessful && !closeAfterSend) {
+          socket.once('drain', () => {
+            resolve();
+          });
+        }
+      } catch (err) {
+        reject(err);
+      }
+    });
+  }
+  
+  /**
+   * Pre-defined TLS alert messages
+   */
+  static readonly alerts = {
+    // Warning level alerts
+    closeNotify: TlsAlert.createWarning(TlsAlert.CLOSE_NOTIFY),
+    unsupportedExtension: TlsAlert.createWarning(TlsAlert.UNSUPPORTED_EXTENSION),
+    certificateRequired: TlsAlert.createWarning(TlsAlert.CERTIFICATE_REQUIRED),
+    unrecognizedName: TlsAlert.createWarning(TlsAlert.UNRECOGNIZED_NAME),
+    noRenegotiation: TlsAlert.createWarning(TlsAlert.NO_RENEGOTIATION),
+    userCanceled: TlsAlert.createWarning(TlsAlert.USER_CANCELED),
+    
+    // Warning level alerts for session resumption
+    certificateExpiredWarning: TlsAlert.createWarning(TlsAlert.CERTIFICATE_EXPIRED),
+    handshakeFailureWarning: TlsAlert.createWarning(TlsAlert.HANDSHAKE_FAILURE),
+    insufficientSecurityWarning: TlsAlert.createWarning(TlsAlert.INSUFFICIENT_SECURITY),
+    
+    // Fatal level alerts
+    unexpectedMessage: TlsAlert.createFatal(TlsAlert.UNEXPECTED_MESSAGE),
+    badRecordMac: TlsAlert.createFatal(TlsAlert.BAD_RECORD_MAC),
+    recordOverflow: TlsAlert.createFatal(TlsAlert.RECORD_OVERFLOW),
+    handshakeFailure: TlsAlert.createFatal(TlsAlert.HANDSHAKE_FAILURE),
+    badCertificate: TlsAlert.createFatal(TlsAlert.BAD_CERTIFICATE),
+    certificateExpired: TlsAlert.createFatal(TlsAlert.CERTIFICATE_EXPIRED),
+    certificateUnknown: TlsAlert.createFatal(TlsAlert.CERTIFICATE_UNKNOWN),
+    illegalParameter: TlsAlert.createFatal(TlsAlert.ILLEGAL_PARAMETER),
+    unknownCA: TlsAlert.createFatal(TlsAlert.UNKNOWN_CA),
+    accessDenied: TlsAlert.createFatal(TlsAlert.ACCESS_DENIED),
+    decodeError: TlsAlert.createFatal(TlsAlert.DECODE_ERROR),
+    decryptError: TlsAlert.createFatal(TlsAlert.DECRYPT_ERROR),
+    protocolVersion: TlsAlert.createFatal(TlsAlert.PROTOCOL_VERSION),
+    insufficientSecurity: TlsAlert.createFatal(TlsAlert.INSUFFICIENT_SECURITY),
+    internalError: TlsAlert.createFatal(TlsAlert.INTERNAL_ERROR),
+  };
+  
+  /**
+   * Utility method to send a warning-level unrecognized_name alert
+   * Specifically designed for SNI issues to encourage the client to retry with SNI
+   * 
+   * @param socket The socket to send the alert to
+   * @returns Promise that resolves when the alert has been sent
+   */
+  static async sendSniRequired(socket: net.Socket): Promise<void> {
+    return this.send(socket, this.LEVEL_WARNING, this.UNRECOGNIZED_NAME);
+  }
+  
+  /**
+   * Utility method to send a close_notify alert and close the connection
+   * 
+   * @param socket The socket to send the alert to
+   * @param closeDelay Milliseconds to wait before closing the connection (default: 200ms)
+   * @returns Promise that resolves when the alert has been sent and the connection closed
+   */
+  static async sendCloseNotify(socket: net.Socket, closeDelay: number = 200): Promise<void> {
+    return this.send(socket, this.LEVEL_WARNING, this.CLOSE_NOTIFY, true, closeDelay);
+  }
+  
+  /**
+   * Utility method to send a certificate_expired alert to force new TLS session
+   * 
+   * @param socket The socket to send the alert to
+   * @param fatal Whether to send as a fatal alert (default: false)
+   * @param closeAfterSend Whether to close the connection after sending the alert (default: true)
+   * @param closeDelay Milliseconds to wait before closing the connection (default: 200ms)
+   * @returns Promise that resolves when the alert has been sent
+   */
+  static async sendCertificateExpired(
+    socket: net.Socket,
+    fatal: boolean = false,
+    closeAfterSend: boolean = true,
+    closeDelay: number = 200
+  ): Promise<void> {
+    const level = fatal ? this.LEVEL_FATAL : this.LEVEL_WARNING;
+    return this.send(socket, level, this.CERTIFICATE_EXPIRED, closeAfterSend, closeDelay);
+  }
+}