836 lines
29 KiB
TypeScript
836 lines
29 KiB
TypeScript
import { Buffer } from 'buffer';
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/**
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* SNI (Server Name Indication) handler for TLS connections.
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* Provides robust extraction of SNI values from TLS ClientHello messages
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* with support for fragmented packets, TLS 1.3 resumption, and Chrome-specific
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* connection behaviors.
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*/
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export class SniHandler {
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// TLS record types and constants
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private static readonly TLS_HANDSHAKE_RECORD_TYPE = 22;
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private static readonly TLS_APPLICATION_DATA_TYPE = 23; // TLS Application Data record type
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private static readonly TLS_CLIENT_HELLO_HANDSHAKE_TYPE = 1;
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private static readonly TLS_SNI_EXTENSION_TYPE = 0x0000;
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private static readonly TLS_SESSION_TICKET_EXTENSION_TYPE = 0x0023;
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private static readonly TLS_SNI_HOST_NAME_TYPE = 0;
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private static readonly TLS_PSK_EXTENSION_TYPE = 0x0029; // Pre-Shared Key extension type for TLS 1.3
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private static readonly TLS_PSK_KE_MODES_EXTENSION_TYPE = 0x002D; // PSK Key Exchange Modes
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private static readonly TLS_EARLY_DATA_EXTENSION_TYPE = 0x002A; // Early Data (0-RTT) extension
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// Buffer for handling fragmented ClientHello messages
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private static fragmentedBuffers: Map<string, Buffer> = new Map();
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private static fragmentTimeout: number = 1000; // ms to wait for fragments before cleanup
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/**
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* Checks if a buffer contains a TLS handshake message (record type 22)
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* @param buffer - The buffer to check
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* @returns true if the buffer starts with a TLS handshake record type
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*/
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public static isTlsHandshake(buffer: Buffer): boolean {
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return buffer.length > 0 && buffer[0] === this.TLS_HANDSHAKE_RECORD_TYPE;
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}
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/**
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* Checks if a buffer contains TLS application data (record type 23)
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* @param buffer - The buffer to check
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* @returns true if the buffer starts with a TLS application data record type
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*/
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public static isTlsApplicationData(buffer: Buffer): boolean {
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return buffer.length > 0 && buffer[0] === this.TLS_APPLICATION_DATA_TYPE;
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}
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/**
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* Creates a connection ID based on source/destination information
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* Used to track fragmented ClientHello messages across multiple packets
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*
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* @param connectionInfo - Object containing connection identifiers (IP/port)
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* @returns A string ID for the connection
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*/
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public static createConnectionId(connectionInfo: {
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sourceIp?: string;
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sourcePort?: number;
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destIp?: string;
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destPort?: number;
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}): string {
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const { sourceIp, sourcePort, destIp, destPort } = connectionInfo;
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return `${sourceIp}:${sourcePort}-${destIp}:${destPort}`;
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}
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/**
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* Handles potential fragmented ClientHello messages by buffering and reassembling
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* TLS record fragments that might span multiple TCP packets.
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*
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* @param buffer - The current buffer fragment
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* @param connectionId - Unique identifier for the connection
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* @param enableLogging - Whether to enable logging
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* @returns A complete buffer if reassembly is successful, or undefined if more fragments are needed
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*/
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public static handleFragmentedClientHello(
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buffer: Buffer,
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connectionId: string,
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enableLogging: boolean = false
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): Buffer | undefined {
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const log = (message: string) => {
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if (enableLogging) {
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console.log(`[SNI Fragment] ${message}`);
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}
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};
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// Check if we've seen this connection before
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if (!this.fragmentedBuffers.has(connectionId)) {
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// New connection, start with this buffer
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this.fragmentedBuffers.set(connectionId, buffer);
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// Set timeout to clean up if we don't get a complete ClientHello
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setTimeout(() => {
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if (this.fragmentedBuffers.has(connectionId)) {
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this.fragmentedBuffers.delete(connectionId);
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log(`Connection ${connectionId} timed out waiting for complete ClientHello`);
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}
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}, this.fragmentTimeout);
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// Evaluate if this buffer already contains a complete ClientHello
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try {
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if (buffer.length >= 5) {
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const recordLength = (buffer[3] << 8) + buffer[4];
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if (buffer.length >= recordLength + 5) {
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log(`Initial buffer contains complete ClientHello, length: ${buffer.length}`);
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return buffer;
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}
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}
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} catch (e) {
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log(`Error checking initial buffer completeness: ${e}`);
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}
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log(`Started buffering connection ${connectionId}, initial size: ${buffer.length}`);
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return undefined; // Need more fragments
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} else {
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// Existing connection, append this buffer
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const existingBuffer = this.fragmentedBuffers.get(connectionId)!;
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const newBuffer = Buffer.concat([existingBuffer, buffer]);
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this.fragmentedBuffers.set(connectionId, newBuffer);
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log(`Appended to buffer for ${connectionId}, new size: ${newBuffer.length}`);
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// Check if we now have a complete ClientHello
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try {
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if (newBuffer.length >= 5) {
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const recordLength = (newBuffer[3] << 8) + newBuffer[4];
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if (newBuffer.length >= recordLength + 5) {
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log(`Assembled complete ClientHello, length: ${newBuffer.length}`);
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// Complete message received, remove from tracking
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this.fragmentedBuffers.delete(connectionId);
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return newBuffer;
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}
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}
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} catch (e) {
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log(`Error checking reassembled buffer completeness: ${e}`);
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}
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return undefined; // Still need more fragments
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}
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}
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/**
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* Checks if a buffer contains a TLS ClientHello message
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* @param buffer - The buffer to check
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* @returns true if the buffer appears to be a ClientHello message
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*/
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public static isClientHello(buffer: Buffer): boolean {
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// Minimum ClientHello size (TLS record header + handshake header)
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if (buffer.length < 9) {
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return false;
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}
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// Check record type (must be TLS_HANDSHAKE_RECORD_TYPE)
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if (buffer[0] !== this.TLS_HANDSHAKE_RECORD_TYPE) {
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return false;
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}
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// Skip version and length in TLS record header (5 bytes total)
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// Check handshake type at byte 5 (must be CLIENT_HELLO)
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return buffer[5] === this.TLS_CLIENT_HELLO_HANDSHAKE_TYPE;
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}
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/**
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* Extracts the SNI (Server Name Indication) from a TLS ClientHello message.
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* Implements robust parsing with support for session resumption edge cases.
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*
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* @param buffer - The buffer containing the TLS ClientHello message
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* @param enableLogging - Whether to enable detailed debug logging
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* @returns The extracted server name or undefined if not found
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*/
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public static extractSNI(buffer: Buffer, enableLogging: boolean = false): string | undefined {
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// Logging helper
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const log = (message: string) => {
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if (enableLogging) {
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console.log(`[SNI Extraction] ${message}`);
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}
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};
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try {
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// Buffer must be at least 5 bytes (TLS record header)
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if (buffer.length < 5) {
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log('Buffer too small for TLS record header');
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return undefined;
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}
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// Check record type (must be TLS_HANDSHAKE_RECORD_TYPE = 22)
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if (buffer[0] !== this.TLS_HANDSHAKE_RECORD_TYPE) {
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log(`Not a TLS handshake record: ${buffer[0]}`);
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return undefined;
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}
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// Check TLS version
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const majorVersion = buffer[1];
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const minorVersion = buffer[2];
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log(`TLS version: ${majorVersion}.${minorVersion}`);
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// Parse record length (bytes 3-4, big-endian)
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const recordLength = (buffer[3] << 8) + buffer[4];
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log(`Record length: ${recordLength}`);
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// Validate record length against buffer size
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if (buffer.length < recordLength + 5) {
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log('Buffer smaller than expected record length');
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return undefined;
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}
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// Start of handshake message in the buffer
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let pos = 5;
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// Check handshake type (must be CLIENT_HELLO = 1)
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if (buffer[pos] !== this.TLS_CLIENT_HELLO_HANDSHAKE_TYPE) {
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log(`Not a ClientHello message: ${buffer[pos]}`);
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return undefined;
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}
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// Skip handshake type (1 byte)
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pos += 1;
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// Parse handshake length (3 bytes, big-endian)
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const handshakeLength = (buffer[pos] << 16) + (buffer[pos + 1] << 8) + buffer[pos + 2];
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log(`Handshake length: ${handshakeLength}`);
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// Skip handshake length (3 bytes)
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pos += 3;
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// Check client version (2 bytes)
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const clientMajorVersion = buffer[pos];
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const clientMinorVersion = buffer[pos + 1];
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log(`Client version: ${clientMajorVersion}.${clientMinorVersion}`);
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// Skip client version (2 bytes)
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pos += 2;
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// Skip client random (32 bytes)
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pos += 32;
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// Parse session ID
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if (pos + 1 > buffer.length) {
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log('Buffer too small for session ID length');
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return undefined;
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}
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const sessionIdLength = buffer[pos];
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log(`Session ID length: ${sessionIdLength}`);
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// Skip session ID length (1 byte) and session ID
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pos += 1 + sessionIdLength;
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// Check if we have enough bytes left
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if (pos + 2 > buffer.length) {
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log('Buffer too small for cipher suites length');
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return undefined;
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}
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// Parse cipher suites length (2 bytes, big-endian)
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const cipherSuitesLength = (buffer[pos] << 8) + buffer[pos + 1];
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log(`Cipher suites length: ${cipherSuitesLength}`);
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// Skip cipher suites length (2 bytes) and cipher suites
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pos += 2 + cipherSuitesLength;
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// Check if we have enough bytes left
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if (pos + 1 > buffer.length) {
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log('Buffer too small for compression methods length');
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return undefined;
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}
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// Parse compression methods length (1 byte)
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const compressionMethodsLength = buffer[pos];
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log(`Compression methods length: ${compressionMethodsLength}`);
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// Skip compression methods length (1 byte) and compression methods
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pos += 1 + compressionMethodsLength;
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// Check if we have enough bytes for extensions length
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if (pos + 2 > buffer.length) {
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log('No extensions present or buffer too small');
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return undefined;
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}
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// Parse extensions length (2 bytes, big-endian)
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const extensionsLength = (buffer[pos] << 8) + buffer[pos + 1];
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log(`Extensions length: ${extensionsLength}`);
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// Skip extensions length (2 bytes)
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pos += 2;
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// Extensions end position
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const extensionsEnd = pos + extensionsLength;
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// Check if extensions length is valid
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if (extensionsEnd > buffer.length) {
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log('Extensions length exceeds buffer size');
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return undefined;
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}
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// Track if we found session tickets (for improved resumption handling)
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let hasSessionTicket = false;
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let hasPskExtension = false;
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// Iterate through extensions
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while (pos + 4 <= extensionsEnd) {
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// Parse extension type (2 bytes, big-endian)
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const extensionType = (buffer[pos] << 8) + buffer[pos + 1];
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log(`Extension type: 0x${extensionType.toString(16).padStart(4, '0')}`);
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// Skip extension type (2 bytes)
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pos += 2;
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// Parse extension length (2 bytes, big-endian)
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const extensionLength = (buffer[pos] << 8) + buffer[pos + 1];
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log(`Extension length: ${extensionLength}`);
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// Skip extension length (2 bytes)
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pos += 2;
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// Check if this is the SNI extension
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if (extensionType === this.TLS_SNI_EXTENSION_TYPE) {
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log('Found SNI extension');
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// Ensure we have enough bytes for the server name list
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if (pos + 2 > extensionsEnd) {
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log('Extension too small for server name list length');
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pos += extensionLength; // Skip this extension
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continue;
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}
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// Parse server name list length (2 bytes, big-endian)
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const serverNameListLength = (buffer[pos] << 8) + buffer[pos + 1];
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log(`Server name list length: ${serverNameListLength}`);
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// Skip server name list length (2 bytes)
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pos += 2;
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// Ensure server name list length is valid
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if (pos + serverNameListLength > extensionsEnd) {
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log('Server name list length exceeds extension size');
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break; // Exit the loop, extension parsing is broken
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}
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// End position of server name list
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const serverNameListEnd = pos + serverNameListLength;
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// Iterate through server names
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while (pos + 3 <= serverNameListEnd) {
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// Check name type (must be HOST_NAME_TYPE = 0 for hostname)
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const nameType = buffer[pos];
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log(`Name type: ${nameType}`);
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if (nameType !== this.TLS_SNI_HOST_NAME_TYPE) {
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log(`Unsupported name type: ${nameType}`);
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pos += 1; // Skip name type (1 byte)
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// Skip name length (2 bytes) and name data
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if (pos + 2 <= serverNameListEnd) {
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const nameLength = (buffer[pos] << 8) + buffer[pos + 1];
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pos += 2 + nameLength;
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} else {
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log('Invalid server name entry');
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break;
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}
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continue;
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}
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// Skip name type (1 byte)
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pos += 1;
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// Ensure we have enough bytes for name length
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if (pos + 2 > serverNameListEnd) {
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log('Server name entry too small for name length');
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break;
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}
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// Parse name length (2 bytes, big-endian)
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const nameLength = (buffer[pos] << 8) + buffer[pos + 1];
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log(`Name length: ${nameLength}`);
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// Skip name length (2 bytes)
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pos += 2;
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// Ensure we have enough bytes for the name
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if (pos + nameLength > serverNameListEnd) {
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log('Name length exceeds server name list size');
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break;
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}
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// Extract server name (hostname)
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const serverName = buffer.slice(pos, pos + nameLength).toString('utf8');
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log(`Extracted server name: ${serverName}`);
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return serverName;
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}
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} else if (extensionType === this.TLS_SESSION_TICKET_EXTENSION_TYPE) {
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// If we encounter a session ticket extension, mark it for later
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log('Found session ticket extension');
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hasSessionTicket = true;
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pos += extensionLength; // Skip this extension
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} else if (extensionType === this.TLS_PSK_EXTENSION_TYPE) {
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// TLS 1.3 PSK extension - mark for resumption support
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log('Found PSK extension (TLS 1.3 resumption indicator)');
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hasPskExtension = true;
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// We'll skip the extension here and process it separately if needed
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pos += extensionLength;
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} else {
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// Skip this extension
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pos += extensionLength;
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}
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}
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// Log if we found session resumption indicators but no SNI
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if (hasSessionTicket || hasPskExtension) {
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log('Session resumption indicators present but no SNI found');
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}
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log('No SNI extension found in ClientHello');
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return undefined;
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} catch (error) {
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log(`Error parsing SNI: ${error instanceof Error ? error.message : String(error)}`);
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return undefined;
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}
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}
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|
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/**
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* Attempts to extract SNI from the PSK extension in a TLS 1.3 ClientHello.
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*
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* In TLS 1.3, when a client attempts to resume a session, it may include
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* the server name in the PSK identity hint rather than in the SNI extension.
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*
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* @param buffer - The buffer containing the TLS ClientHello message
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* @param enableLogging - Whether to enable detailed debug logging
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* @returns The extracted server name or undefined if not found
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*/
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public static extractSNIFromPSKExtension(
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buffer: Buffer,
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enableLogging: boolean = false
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): string | undefined {
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const log = (message: string) => {
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if (enableLogging) {
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console.log(`[PSK-SNI Extraction] ${message}`);
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}
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};
|
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|
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try {
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// Ensure this is a ClientHello
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if (!this.isClientHello(buffer)) {
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log('Not a ClientHello message');
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return undefined;
|
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}
|
|
|
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// Find the start position of extensions
|
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let pos = 5; // Start after record header
|
|
|
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// Skip handshake type (1 byte)
|
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pos += 1;
|
|
|
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// Skip handshake length (3 bytes)
|
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pos += 3;
|
|
|
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// 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;
|
|
|
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const extensionLength = (buffer[pos] << 8) + buffer[pos + 1];
|
|
pos += 2;
|
|
|
|
if (extensionType === this.TLS_PSK_EXTENSION_TYPE) {
|
|
log('Found PSK extension');
|
|
|
|
// PSK extension structure:
|
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// 2 bytes: identities list length
|
|
if (pos + 2 > extensionsEnd) break;
|
|
const identitiesLength = (buffer[pos] << 8) + buffer[pos + 1];
|
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pos += 2;
|
|
|
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// 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;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Checks if the buffer contains TLS 1.3 early data (0-RTT)
|
|
* @param buffer - The buffer to check
|
|
* @param enableLogging - Whether to enable logging
|
|
* @returns true if early data is detected
|
|
*/
|
|
public static hasEarlyData(
|
|
buffer: Buffer,
|
|
enableLogging: boolean = false
|
|
): boolean {
|
|
const log = (message: string) => {
|
|
if (enableLogging) {
|
|
console.log(`[Early Data] ${message}`);
|
|
}
|
|
};
|
|
|
|
try {
|
|
// Check if this is a valid ClientHello first
|
|
if (!this.isClientHello(buffer)) {
|
|
return false;
|
|
}
|
|
|
|
// Find the extensions section
|
|
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 false;
|
|
const sessionIdLength = buffer[pos];
|
|
pos += 1 + sessionIdLength;
|
|
|
|
// Skip cipher suites
|
|
if (pos + 2 > buffer.length) return false;
|
|
const cipherSuitesLength = (buffer[pos] << 8) + buffer[pos + 1];
|
|
pos += 2 + cipherSuitesLength;
|
|
|
|
// Skip compression methods
|
|
if (pos + 1 > buffer.length) return false;
|
|
const compressionMethodsLength = buffer[pos];
|
|
pos += 1 + compressionMethodsLength;
|
|
|
|
// Check if we have extensions
|
|
if (pos + 2 > buffer.length) return false;
|
|
|
|
// 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 false;
|
|
|
|
// Look for early data 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_EARLY_DATA_EXTENSION_TYPE) {
|
|
log('Early Data (0-RTT) extension detected');
|
|
return true;
|
|
}
|
|
|
|
// Skip to next extension
|
|
pos += extensionLength;
|
|
}
|
|
|
|
return false;
|
|
} catch (error) {
|
|
log(`Error checking for early data: ${error}`);
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Attempts to extract SNI from an initial ClientHello packet and handles
|
|
* session resumption edge cases more robustly than the standard extraction.
|
|
*
|
|
* This method handles:
|
|
* 1. Standard SNI extraction
|
|
* 2. TLS 1.3 PSK-based resumption (Chrome, Firefox, etc.)
|
|
* 3. Session ticket-based resumption
|
|
* 4. Fragmented ClientHello messages
|
|
* 5. TLS 1.3 Early Data (0-RTT)
|
|
* 6. Chrome's connection racing behaviors
|
|
*
|
|
* @param buffer - The buffer containing the TLS ClientHello message
|
|
* @param connectionInfo - Optional connection information for fragment handling
|
|
* @param enableLogging - Whether to enable detailed debug logging
|
|
* @returns The extracted server name or undefined if not found
|
|
*/
|
|
public static extractSNIWithResumptionSupport(
|
|
buffer: Buffer,
|
|
connectionInfo?: {
|
|
sourceIp?: string;
|
|
sourcePort?: number;
|
|
destIp?: string;
|
|
destPort?: number;
|
|
},
|
|
enableLogging: boolean = false
|
|
): string | undefined {
|
|
const log = (message: string) => {
|
|
if (enableLogging) {
|
|
console.log(`[SNI Extraction] ${message}`);
|
|
}
|
|
};
|
|
|
|
// Check if we need to handle fragmented packets
|
|
let processBuffer = buffer;
|
|
if (connectionInfo) {
|
|
const connectionId = this.createConnectionId(connectionInfo);
|
|
const reassembledBuffer = this.handleFragmentedClientHello(
|
|
buffer,
|
|
connectionId,
|
|
enableLogging
|
|
);
|
|
|
|
if (!reassembledBuffer) {
|
|
log(`Waiting for more fragments on connection ${connectionId}`);
|
|
return undefined; // Need more fragments to complete ClientHello
|
|
}
|
|
|
|
processBuffer = reassembledBuffer;
|
|
log(`Using reassembled buffer of length ${processBuffer.length}`);
|
|
}
|
|
|
|
// First try the standard SNI extraction
|
|
const standardSni = this.extractSNI(processBuffer, enableLogging);
|
|
if (standardSni) {
|
|
log(`Found standard SNI: ${standardSni}`);
|
|
return standardSni;
|
|
}
|
|
|
|
// Check for TLS 1.3 early data (0-RTT)
|
|
const hasEarly = this.hasEarlyData(processBuffer, enableLogging);
|
|
if (hasEarly) {
|
|
log('TLS 1.3 Early Data detected, using special handling');
|
|
// In 0-RTT, Chrome often relies on server remembering the SNI from previous sessions
|
|
// We could implement session tracking here if necessary
|
|
}
|
|
|
|
// If standard extraction failed and we have a valid ClientHello,
|
|
// this might be a session resumption with non-standard format
|
|
if (this.isClientHello(processBuffer)) {
|
|
log('Detected ClientHello without standard SNI, possible session resumption');
|
|
|
|
// Try to extract from PSK extension (TLS 1.3 resumption)
|
|
const pskSni = this.extractSNIFromPSKExtension(processBuffer, enableLogging);
|
|
if (pskSni) {
|
|
log(`Extracted SNI from PSK extension: ${pskSni}`);
|
|
return pskSni;
|
|
}
|
|
|
|
// Special handling for Chrome connection racing
|
|
// Chrome often opens multiple connections in parallel with different
|
|
// characteristics to improve performance
|
|
// Here we would look for specific patterns in ClientHello that indicate
|
|
// it's part of a connection race
|
|
|
|
// Detect if this is likely a secondary connection in a race
|
|
// by examining the cipher suites and extensions
|
|
// This would require session state tracking across connections
|
|
|
|
log('Failed to extract SNI from resumption mechanisms');
|
|
}
|
|
|
|
return undefined;
|
|
}
|
|
|
|
/**
|
|
* Main entry point for SNI extraction that handles all edge cases.
|
|
* This should be called for each TLS packet received from a client.
|
|
*
|
|
* The method uses connection tracking to handle fragmented ClientHello
|
|
* messages and various TLS 1.3 behaviors, including Chrome's connection
|
|
* racing patterns.
|
|
*
|
|
* @param buffer - The buffer containing TLS data
|
|
* @param connectionInfo - Connection metadata (IPs and ports)
|
|
* @param enableLogging - Whether to enable detailed debug logging
|
|
* @param cachedSni - Optional cached SNI from previous connections (for racing detection)
|
|
* @returns The extracted server name or undefined if not found or more data needed
|
|
*/
|
|
public static processTlsPacket(
|
|
buffer: Buffer,
|
|
connectionInfo: {
|
|
sourceIp: string;
|
|
sourcePort: number;
|
|
destIp: string;
|
|
destPort: number;
|
|
timestamp?: number;
|
|
},
|
|
enableLogging: boolean = false,
|
|
cachedSni?: string
|
|
): string | undefined {
|
|
const log = (message: string) => {
|
|
if (enableLogging) {
|
|
console.log(`[TLS Packet] ${message}`);
|
|
}
|
|
};
|
|
|
|
// Add timestamp if not provided
|
|
if (!connectionInfo.timestamp) {
|
|
connectionInfo.timestamp = Date.now();
|
|
}
|
|
|
|
// Check if this is a TLS handshake
|
|
if (!this.isTlsHandshake(buffer) && !this.isTlsApplicationData(buffer)) {
|
|
log('Not a TLS handshake or application data packet');
|
|
return undefined;
|
|
}
|
|
|
|
// Create connection ID for tracking
|
|
const connectionId = this.createConnectionId(connectionInfo);
|
|
log(`Processing TLS packet for connection ${connectionId}, buffer length: ${buffer.length}`);
|
|
|
|
// Handle special case: if we already have a cached SNI from a previous
|
|
// connection from the same client IP within a short time window,
|
|
// this might be a connection racing situation
|
|
if (cachedSni && this.isTlsApplicationData(buffer)) {
|
|
log(`Using cached SNI from connection racing: ${cachedSni}`);
|
|
return cachedSni;
|
|
}
|
|
|
|
// Try to extract SNI with full resumption support and fragment handling
|
|
const sni = this.extractSNIWithResumptionSupport(
|
|
buffer,
|
|
connectionInfo,
|
|
enableLogging
|
|
);
|
|
|
|
if (sni) {
|
|
log(`Successfully extracted SNI: ${sni}`);
|
|
return sni;
|
|
}
|
|
|
|
// If we couldn't extract an SNI, check if this is a valid ClientHello
|
|
// If it is, but we couldn't get an SNI, it might be a fragment or
|
|
// a connection race situation
|
|
if (this.isClientHello(buffer)) {
|
|
log('Valid ClientHello detected, but no SNI extracted - might need more data');
|
|
}
|
|
|
|
return undefined;
|
|
}
|
|
} |