fix(tls/sni): Improve logging for TLS session resumption by extracting and logging SNI values from ClientHello messages.

changelog.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 2025-03-12 - 3.41.4 - fix(tls/sni)
+Improve logging for TLS session resumption by extracting and logging SNI values from ClientHello messages.
+
+- Added logging to output the extracted SNI value during renegotiation, initial ClientHello and in the SNI handler.
+- Enhanced error handling during SNI extraction to aid troubleshooting of TLS session resumption issues.
+
 ## 2025-03-12 - 3.41.3 - fix(TLS/SNI)
 Improve TLS session resumption handling and logging. Now, session resumption attempts are always logged with details, and connections without a proper SNI are rejected when allowSessionTicket is disabled. In addition, empty SNI extensions are explicitly treated as missing, ensuring stricter and more consistent TLS handshake validation.
 

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartproxy',
-  version: '3.41.3',
+  version: '3.41.4',
   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.portproxy.ts

@@ -945,9 +945,13 @@ export class PortProxy {
                 
                 if (resumptionInfo.isResumption) {
                   // Always log resumption attempt for easier debugging
+                  // Try to extract SNI for logging
+                  const extractedSNI = SniHandler.extractSNI(renegChunk, this.settings.enableTlsDebugLogging);
                   console.log(
                     `[${connectionId}] Session resumption detected in renegotiation. ` +
-                    `Has SNI: ${resumptionInfo.hasSNI ? 'Yes' : 'No'}, allowSessionTicket: ${this.settings.allowSessionTicket}`
+                    `Has SNI: ${resumptionInfo.hasSNI ? 'Yes' : 'No'}, ` +
+                    `SNI value: ${extractedSNI || 'None'}, ` +
+                    `allowSessionTicket: ${this.settings.allowSessionTicket}`
                   );
                   
                   // Block if there's session resumption without SNI
@@ -1585,9 +1589,13 @@ export class PortProxy {
               
               if (resumptionInfo.isResumption) {
                 // Always log resumption attempt for easier debugging
+                // Try to extract SNI for logging
+                const extractedSNI = SniHandler.extractSNI(chunk, this.settings.enableTlsDebugLogging);
                 console.log(
                   `[${connectionId}] Session resumption detected in initial ClientHello. ` +
-                  `Has SNI: ${resumptionInfo.hasSNI ? 'Yes' : 'No'}, allowSessionTicket: ${this.settings.allowSessionTicket}`
+                  `Has SNI: ${resumptionInfo.hasSNI ? 'Yes' : 'No'}, ` +
+                  `SNI value: ${extractedSNI || 'None'}, ` +
+                  `allowSessionTicket: ${this.settings.allowSessionTicket}`
                 );
                 
                 // Block if there's session resumption without SNI
@@ -1967,9 +1975,13 @@ export class PortProxy {
                 
                 if (resumptionInfo.isResumption) {
                   // Always log resumption attempt for easier debugging
+                  // Try to extract SNI for logging
+                  const extractedSNI = SniHandler.extractSNI(chunk, this.settings.enableTlsDebugLogging);
                   console.log(
                     `[${connectionId}] Session resumption detected in SNI handler. ` +
-                    `Has SNI: ${resumptionInfo.hasSNI ? 'Yes' : 'No'}, allowSessionTicket: ${this.settings.allowSessionTicket}`
+                    `Has SNI: ${resumptionInfo.hasSNI ? 'Yes' : 'No'}, ` +
+                    `SNI value: ${extractedSNI || 'None'}, ` +
+                    `allowSessionTicket: ${this.settings.allowSessionTicket}`
                   );
                   
                   // Block if there's session resumption without SNI

ts/classes.snihandler.ts

@@ -413,7 +413,36 @@ export class SniHandler {
                     // Check that the SNI extension actually has content
                     if (extensionLength > 0) {
                       hasSNI = true;
-                      log('Found SNI extension with length: ' + extensionLength);
+                      
+                      // Try to extract the actual SNI value for logging
+                      try {
+                        // Skip to server_name_list_length (2 bytes)
+                        const tempPos = pos;
+                        if (tempPos + 2 <= extensionsEnd) {
+                          const nameListLength = (buffer[tempPos] << 8) + buffer[tempPos + 1];
+                          
+                          // Skip server_name_list_length (2 bytes)
+                          if (tempPos + 2 + 1 <= extensionsEnd) {
+                            // Check name_type (should be 0 for hostname)
+                            if (buffer[tempPos + 2] === 0) {
+                              // Skip name_type (1 byte)
+                              if (tempPos + 3 + 2 <= extensionsEnd) {
+                                // Get name_length (2 bytes)
+                                const nameLength = (buffer[tempPos + 3] << 8) + buffer[tempPos + 4];
+                                
+                                // Extract the hostname
+                                if (tempPos + 5 + nameLength <= extensionsEnd) {
+                                  const hostname = buffer.slice(tempPos + 5, tempPos + 5 + nameLength).toString('utf8');
+                                  log(`Found SNI extension with server_name: ${hostname}`);
+                                }
+                              }
+                            }
+                          }
+                        }
+                      } catch (e) {
+                        log(`Error extracting SNI value: ${e}`);
+                        log('Found SNI extension with length: ' + extensionLength);
+                      }
                     } else {
                       log('Found empty SNI extension, treating as no SNI');
                     }