fix(snihandler): Enhance SNI extraction to support TLS 1.3 PSK-based session resumption by adding a dedicated extractSNIFromPSKExtension method and improved logging for session resumption indicators.

changelog.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 2025-03-11 - 3.37.3 - fix(snihandler)
+Enhance SNI extraction to support TLS 1.3 PSK-based session resumption by adding a dedicated extractSNIFromPSKExtension method and improved logging for session resumption indicators.
+
+- Defined TLS_PSK_EXTENSION_TYPE and TLS_PSK_KE_MODES_EXTENSION_TYPE constants.
+- Added extractSNIFromPSKExtension method to handle ClientHello messages containing PSK identities.
+- Improved logging to indicate when session resumption indicators (ticket or PSK) are present but no standard SNI is found.
+- Enhanced extractSNIWithResumptionSupport to attempt PSK extraction if standard SNI extraction fails.
+
 ## 2025-03-11 - 3.37.2 - fix(PortProxy)
 Improve buffering and data handling during connection setup in PortProxy to prevent data loss
 

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartproxy',
-  version: '3.37.2',
+  version: '3.37.3',
   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.snihandler.ts

@@ -11,6 +11,8 @@ export class SniHandler {
   private static readonly TLS_SNI_EXTENSION_TYPE = 0x0000;
   private static readonly TLS_SESSION_TICKET_EXTENSION_TYPE = 0x0023;
   private static readonly TLS_SNI_HOST_NAME_TYPE = 0;
+  private static readonly TLS_PSK_EXTENSION_TYPE = 0x0029; // Pre-Shared Key extension type for TLS 1.3
+  private static readonly TLS_PSK_KE_MODES_EXTENSION_TYPE = 0x002D; // PSK Key Exchange Modes
 
   /**
    * Checks if a buffer contains a TLS handshake message (record type 22)
@@ -178,6 +180,7 @@ export class SniHandler {
 
       // Track if we found session tickets (for improved resumption handling)
       let hasSessionTicket = false;
+      let hasPskExtension = false;
 
       // Iterate through extensions
       while (pos + 4 <= extensionsEnd) {
@@ -275,15 +278,21 @@ export class SniHandler {
           log('Found session ticket extension');
           hasSessionTicket = true;
           pos += extensionLength; // Skip this extension
+        } else if (extensionType === this.TLS_PSK_EXTENSION_TYPE) {
+          // TLS 1.3 PSK extension - mark for resumption support
+          log('Found PSK extension (TLS 1.3 resumption indicator)');
+          hasPskExtension = true;
+          // We'll skip the extension here and process it separately if needed
+          pos += extensionLength;
         } else {
           // Skip this extension
           pos += extensionLength;
         }
       }
 
-      // Log if we found a session ticket but no SNI
+      // Log if we found session resumption indicators but no SNI
-      if (hasSessionTicket) {
+      if (hasSessionTicket || hasPskExtension) {
-        log('Session ticket present but no SNI found - possible resumption scenario');
+        log('Session resumption indicators present but no SNI found');
       }
 
       log('No SNI extension found in ClientHello');
@@ -294,12 +303,177 @@ export class SniHandler {
     }
   }
 
+  /**
+   * Attempts to extract SNI from the PSK extension in a TLS 1.3 ClientHello.
+   * 
+   * In TLS 1.3, when a client attempts to resume a session, it may include 
+   * the server name in the PSK identity hint rather than in the SNI extension.
+   * 
+   * @param buffer - The buffer containing the TLS ClientHello message
+   * @param enableLogging - Whether to enable detailed debug logging
+   * @returns The extracted server name or undefined if not found
+   */
+  public static extractSNIFromPSKExtension(
+    buffer: Buffer,
+    enableLogging: boolean = false
+  ): string | undefined {
+    const log = (message: string) => {
+      if (enableLogging) {
+        console.log(`[PSK-SNI Extraction] ${message}`);
+      }
+    };
+
+    try {
+      // Ensure this is a ClientHello
+      if (!this.isClientHello(buffer)) {
+        log('Not a ClientHello message');
+        return undefined;
+      }
+
+      // Find the start position of extensions
+      let pos = 5; // Start after record header
+      
+      // Skip handshake type (1 byte)
+      pos += 1;
+      
+      // Skip handshake length (3 bytes)
+      pos += 3;
+      
+      // Skip client version (2 bytes)
+      pos += 2;
+      
+      // Skip client random (32 bytes)
+      pos += 32;
+      
+      // Skip session ID
+      if (pos + 1 > buffer.length) return undefined;
+      const sessionIdLength = buffer[pos];
+      pos += 1 + sessionIdLength;
+      
+      // Skip cipher suites
+      if (pos + 2 > buffer.length) return undefined;
+      const cipherSuitesLength = (buffer[pos] << 8) + buffer[pos + 1];
+      pos += 2 + cipherSuitesLength;
+      
+      // Skip compression methods
+      if (pos + 1 > buffer.length) return undefined;
+      const compressionMethodsLength = buffer[pos];
+      pos += 1 + compressionMethodsLength;
+      
+      // Check if we have extensions
+      if (pos + 2 > buffer.length) {
+        log('No extensions present');
+        return undefined;
+      }
+      
+      // Get extensions length
+      const extensionsLength = (buffer[pos] << 8) + buffer[pos + 1];
+      pos += 2;
+      
+      // Extensions end position
+      const extensionsEnd = pos + extensionsLength;
+      if (extensionsEnd > buffer.length) return undefined;
+
+      // Look for PSK extension
+      while (pos + 4 <= extensionsEnd) {
+        const extensionType = (buffer[pos] << 8) + buffer[pos + 1];
+        pos += 2;
+        
+        const extensionLength = (buffer[pos] << 8) + buffer[pos + 1];
+        pos += 2;
+        
+        if (extensionType === this.TLS_PSK_EXTENSION_TYPE) {
+          log('Found PSK extension');
+          
+          // PSK extension structure:
+          // 2 bytes: identities list length
+          if (pos + 2 > extensionsEnd) break;
+          const identitiesLength = (buffer[pos] << 8) + buffer[pos + 1];
+          pos += 2;
+          
+          // End of identities list
+          const identitiesEnd = pos + identitiesLength;
+          if (identitiesEnd > extensionsEnd) break;
+          
+          // Process each PSK identity
+          while (pos + 2 <= identitiesEnd) {
+            // Identity length (2 bytes)
+            if (pos + 2 > identitiesEnd) break;
+            const identityLength = (buffer[pos] << 8) + buffer[pos + 1];
+            pos += 2;
+            
+            if (pos + identityLength > identitiesEnd) break;
+            
+            // Try to extract hostname from identity
+            // Chrome often embeds the hostname in the PSK identity
+            // This is a heuristic as there's no standard format
+            if (identityLength > 0) {
+              const identity = buffer.slice(pos, pos + identityLength);
+              
+              // Skip identity bytes
+              pos += identityLength;
+              
+              // Skip obfuscated ticket age (4 bytes)
+              pos += 4;
+              
+              // Try to parse the identity as UTF-8
+              try {
+                const identityStr = identity.toString('utf8');
+                log(`PSK identity: ${identityStr}`);
+                
+                // Check if the identity contains hostname hints
+                // Chrome often embeds the hostname in a known format
+                // Try to extract using common patterns
+                
+                // Pattern 1: Look for domain name pattern
+                const domainPattern = /([a-z0-9]([a-z0-9-]{0,61}[a-z0-9])?\.)+[a-z0-9]([a-z0-9-]{0,61}[a-z0-9])?/i;
+                const domainMatch = identityStr.match(domainPattern);
+                if (domainMatch && domainMatch[0]) {
+                  log(`Found domain in PSK identity: ${domainMatch[0]}`);
+                  return domainMatch[0];
+                }
+                
+                // Pattern 2: Chrome sometimes uses a specific format with delimiters
+                // This is a heuristic approach since the format isn't standardized
+                const parts = identityStr.split('|');
+                if (parts.length > 1) {
+                  for (const part of parts) {
+                    if (part.includes('.') && !part.includes('/')) {
+                      const possibleDomain = part.trim();
+                      if (/^[a-z0-9.-]+$/i.test(possibleDomain)) {
+                        log(`Found possible domain in PSK delimiter format: ${possibleDomain}`);
+                        return possibleDomain;
+                      }
+                    }
+                  }
+                }
+              } catch (e) {
+                log('Failed to parse PSK identity as UTF-8');
+              }
+            }
+          }
+        } else {
+          // Skip this extension
+          pos += extensionLength;
+        }
+      }
+      
+      log('No hostname found in PSK extension');
+      return undefined;
+    } catch (error) {
+      log(`Error parsing PSK: ${error instanceof Error ? error.message : String(error)}`);
+      return undefined;
+    }
+  }
+
   /**
    * Attempts to extract SNI from an initial ClientHello packet and handles
    * session resumption edge cases more robustly than the standard extraction.
    * 
-   * This method is specifically designed for Chrome and other browsers that
+   * This method handles:
-   * may send different ClientHello formats during session resumption.
+   * 1. Standard SNI extraction
+   * 2. TLS 1.3 PSK-based resumption (Chrome, Firefox, etc.)
+   * 3. Session ticket-based resumption
    * 
    * @param buffer - The buffer containing the TLS ClientHello message
    * @param enableLogging - Whether to enable detailed debug logging
@@ -312,6 +486,9 @@ export class SniHandler {
     // First try the standard SNI extraction
     const standardSni = this.extractSNI(buffer, enableLogging);
     if (standardSni) {
+      if (enableLogging) {
+        console.log(`[SNI Extraction] Found standard SNI: ${standardSni}`);
+      }
       return standardSni;
     }
     
@@ -322,8 +499,19 @@ export class SniHandler {
         console.log('[SNI Extraction] Detected ClientHello without standard SNI, possible session resumption');
       }
       
-      // Additional handling could be implemented here for specific browser behaviors
+      // Try to extract from PSK extension (TLS 1.3 resumption)
-      // For now, this is a placeholder for future improvements
+      const pskSni = this.extractSNIFromPSKExtension(buffer, enableLogging);
+      if (pskSni) {
+        if (enableLogging) {
+          console.log(`[SNI Extraction] Extracted SNI from PSK extension: ${pskSni}`);
+        }
+        return pskSni;
+      }
+      
+      // Could add more browser-specific heuristics here if needed
+      if (enableLogging) {
+        console.log('[SNI Extraction] Failed to extract SNI from resumption mechanisms');
+      }
     }
     
     return undefined;