fix(detection): fix SNI detection in TLS detector

ts/protocols/common/fragment-handler.ts

@@ -0,0 +1,163 @@
+/**
+ * Shared Fragment Handler for Protocol Detection
+ * 
+ * Provides unified fragment buffering and reassembly for protocols
+ * that may span multiple TCP packets.
+ */
+
+import { Buffer } from 'buffer';
+
+/**
+ * Fragment tracking information
+ */
+export interface IFragmentInfo {
+  buffer: Buffer;
+  timestamp: number;
+  connectionId: string;
+}
+
+/**
+ * Options for fragment handling
+ */
+export interface IFragmentOptions {
+  maxBufferSize?: number;
+  timeout?: number;
+  cleanupInterval?: number;
+}
+
+/**
+ * Result of fragment processing
+ */
+export interface IFragmentResult {
+  isComplete: boolean;
+  buffer?: Buffer;
+  needsMoreData: boolean;
+  error?: string;
+}
+
+/**
+ * Shared fragment handler for protocol detection
+ */
+export class FragmentHandler {
+  private fragments = new Map<string, IFragmentInfo>();
+  private cleanupTimer?: NodeJS.Timeout;
+  
+  constructor(private options: IFragmentOptions = {}) {
+    // Start cleanup timer if not already running
+    if (options.cleanupInterval && !this.cleanupTimer) {
+      this.cleanupTimer = setInterval(
+        () => this.cleanup(),
+        options.cleanupInterval
+      );
+    }
+  }
+  
+  /**
+   * Add a fragment for a connection
+   */
+  addFragment(connectionId: string, fragment: Buffer): IFragmentResult {
+    const existing = this.fragments.get(connectionId);
+    
+    if (existing) {
+      // Append to existing buffer
+      const newBuffer = Buffer.concat([existing.buffer, fragment]);
+      
+      // Check size limit
+      const maxSize = this.options.maxBufferSize || 65536;
+      if (newBuffer.length > maxSize) {
+        this.fragments.delete(connectionId);
+        return {
+          isComplete: false,
+          needsMoreData: false,
+          error: 'Buffer size exceeded maximum allowed'
+        };
+      }
+      
+      // Update fragment info
+      this.fragments.set(connectionId, {
+        buffer: newBuffer,
+        timestamp: Date.now(),
+        connectionId
+      });
+      
+      return {
+        isComplete: false,
+        buffer: newBuffer,
+        needsMoreData: true
+      };
+    } else {
+      // New fragment
+      this.fragments.set(connectionId, {
+        buffer: fragment,
+        timestamp: Date.now(),
+        connectionId
+      });
+      
+      return {
+        isComplete: false,
+        buffer: fragment,
+        needsMoreData: true
+      };
+    }
+  }
+  
+  /**
+   * Get the current buffer for a connection
+   */
+  getBuffer(connectionId: string): Buffer | undefined {
+    return this.fragments.get(connectionId)?.buffer;
+  }
+  
+  /**
+   * Mark a connection as complete and clean up
+   */
+  complete(connectionId: string): void {
+    this.fragments.delete(connectionId);
+  }
+  
+  /**
+   * Check if we're tracking a connection
+   */
+  hasConnection(connectionId: string): boolean {
+    return this.fragments.has(connectionId);
+  }
+  
+  /**
+   * Clean up expired fragments
+   */
+  cleanup(): void {
+    const now = Date.now();
+    const timeout = this.options.timeout || 5000;
+    
+    for (const [connectionId, info] of this.fragments.entries()) {
+      if (now - info.timestamp > timeout) {
+        this.fragments.delete(connectionId);
+      }
+    }
+  }
+  
+  /**
+   * Clear all fragments
+   */
+  clear(): void {
+    this.fragments.clear();
+  }
+  
+  /**
+   * Destroy the handler and clean up resources
+   */
+  destroy(): void {
+    if (this.cleanupTimer) {
+      clearInterval(this.cleanupTimer);
+      this.cleanupTimer = undefined;
+    }
+    this.clear();
+  }
+  
+  /**
+   * Get the number of tracked connections
+   */
+  get size(): number {
+    return this.fragments.size;
+  }
+}