update structure
This commit is contained in:
353
ts/tls/sni/sni-extraction.ts
Normal file
353
ts/tls/sni/sni-extraction.ts
Normal file
@ -0,0 +1,353 @@
|
||||
import { Buffer } from 'buffer';
|
||||
import { TlsExtensionType, TlsUtils } from '../utils/tls-utils.js';
|
||||
import {
|
||||
ClientHelloParser,
|
||||
type LoggerFunction
|
||||
} from './client-hello-parser.js';
|
||||
|
||||
/**
|
||||
* Connection tracking information
|
||||
*/
|
||||
export interface ConnectionInfo {
|
||||
sourceIp: string;
|
||||
sourcePort: number;
|
||||
destIp: string;
|
||||
destPort: number;
|
||||
timestamp?: number;
|
||||
}
|
||||
|
||||
/**
|
||||
* Utilities for extracting SNI information from TLS handshakes
|
||||
*/
|
||||
export class SniExtraction {
|
||||
/**
|
||||
* Extracts the SNI (Server Name Indication) from a TLS ClientHello message.
|
||||
*
|
||||
* @param buffer The buffer containing the TLS ClientHello message
|
||||
* @param logger Optional logging function
|
||||
* @returns The extracted server name or undefined if not found
|
||||
*/
|
||||
public static extractSNI(buffer: Buffer, logger?: LoggerFunction): string | undefined {
|
||||
const log = logger || (() => {});
|
||||
|
||||
try {
|
||||
// Parse the ClientHello
|
||||
const parseResult = ClientHelloParser.parseClientHello(buffer, logger);
|
||||
if (!parseResult.isValid) {
|
||||
log(`Failed to parse ClientHello: ${parseResult.error}`);
|
||||
return undefined;
|
||||
}
|
||||
|
||||
// Check if ServerName extension was found
|
||||
if (parseResult.serverNameList && parseResult.serverNameList.length > 0) {
|
||||
// Use the first hostname (most common case)
|
||||
const serverName = parseResult.serverNameList[0];
|
||||
log(`Found SNI: ${serverName}`);
|
||||
return serverName;
|
||||
}
|
||||
|
||||
log('No SNI extension found in ClientHello');
|
||||
return undefined;
|
||||
} catch (error) {
|
||||
log(`Error extracting SNI: ${error instanceof Error ? error.message : String(error)}`);
|
||||
return undefined;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* 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 logger Optional logging function
|
||||
* @returns The extracted server name or undefined if not found
|
||||
*/
|
||||
public static extractSNIFromPSKExtension(
|
||||
buffer: Buffer,
|
||||
logger?: LoggerFunction
|
||||
): string | undefined {
|
||||
const log = logger || (() => {});
|
||||
|
||||
try {
|
||||
// Ensure this is a ClientHello
|
||||
if (!TlsUtils.isClientHello(buffer)) {
|
||||
log('Not a ClientHello message');
|
||||
return undefined;
|
||||
}
|
||||
|
||||
// Parse the ClientHello to find PSK extension
|
||||
const parseResult = ClientHelloParser.parseClientHello(buffer, logger);
|
||||
if (!parseResult.isValid || !parseResult.extensions) {
|
||||
return undefined;
|
||||
}
|
||||
|
||||
// Find the PSK extension
|
||||
const pskExtension = parseResult.extensions.find(ext =>
|
||||
ext.type === TlsExtensionType.PRE_SHARED_KEY);
|
||||
|
||||
if (!pskExtension) {
|
||||
log('No PSK extension found');
|
||||
return undefined;
|
||||
}
|
||||
|
||||
// Parse the PSK extension data
|
||||
const data = pskExtension.data;
|
||||
|
||||
// PSK extension structure:
|
||||
// 2 bytes: identities list length
|
||||
if (data.length < 2) return undefined;
|
||||
|
||||
const identitiesLength = (data[0] << 8) + data[1];
|
||||
let pos = 2;
|
||||
|
||||
// End of identities list
|
||||
const identitiesEnd = pos + identitiesLength;
|
||||
if (identitiesEnd > data.length) return undefined;
|
||||
|
||||
// Process each PSK identity
|
||||
while (pos + 2 <= identitiesEnd) {
|
||||
// Identity length (2 bytes)
|
||||
if (pos + 2 > identitiesEnd) break;
|
||||
|
||||
const identityLength = (data[pos] << 8) + data[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 = data.slice(pos, pos + identityLength);
|
||||
|
||||
// Skip identity bytes
|
||||
pos += identityLength;
|
||||
|
||||
// Skip obfuscated ticket age (4 bytes)
|
||||
if (pos + 4 <= identitiesEnd) {
|
||||
pos += 4;
|
||||
} else {
|
||||
break;
|
||||
}
|
||||
|
||||
// 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');
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
log('No hostname found in PSK extension');
|
||||
return undefined;
|
||||
} catch (error) {
|
||||
log(`Error parsing PSK: ${error instanceof Error ? error.message : String(error)}`);
|
||||
return undefined;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Main entry point for SNI extraction with support for fragmented messages
|
||||
* and session resumption edge cases.
|
||||
*
|
||||
* @param buffer The buffer containing TLS data
|
||||
* @param connectionInfo Connection tracking information
|
||||
* @param logger Optional logging function
|
||||
* @param cachedSni Optional previously cached SNI value
|
||||
* @returns The extracted server name or undefined
|
||||
*/
|
||||
public static extractSNIWithResumptionSupport(
|
||||
buffer: Buffer,
|
||||
connectionInfo?: ConnectionInfo,
|
||||
logger?: LoggerFunction,
|
||||
cachedSni?: string
|
||||
): string | undefined {
|
||||
const log = logger || (() => {});
|
||||
|
||||
// Log buffer details for debugging
|
||||
if (logger) {
|
||||
log(`Buffer size: ${buffer.length} bytes`);
|
||||
log(`Buffer starts with: ${buffer.slice(0, Math.min(10, buffer.length)).toString('hex')}`);
|
||||
|
||||
if (buffer.length >= 5) {
|
||||
const recordType = buffer[0];
|
||||
const majorVersion = buffer[1];
|
||||
const minorVersion = buffer[2];
|
||||
const recordLength = (buffer[3] << 8) + buffer[4];
|
||||
|
||||
log(
|
||||
`TLS Record: type=${recordType}, version=${majorVersion}.${minorVersion}, length=${recordLength}`
|
||||
);
|
||||
}
|
||||
}
|
||||
|
||||
// Check if we need to handle fragmented packets
|
||||
let processBuffer = buffer;
|
||||
if (connectionInfo) {
|
||||
const connectionId = TlsUtils.createConnectionId(connectionInfo);
|
||||
const reassembledBuffer = ClientHelloParser.handleFragmentedClientHello(
|
||||
buffer,
|
||||
connectionId,
|
||||
logger
|
||||
);
|
||||
|
||||
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, logger);
|
||||
if (standardSni) {
|
||||
log(`Found standard SNI: ${standardSni}`);
|
||||
return standardSni;
|
||||
}
|
||||
|
||||
// Check for session resumption when standard SNI extraction fails
|
||||
if (TlsUtils.isClientHello(processBuffer)) {
|
||||
const resumptionInfo = ClientHelloParser.hasSessionResumption(processBuffer, logger);
|
||||
|
||||
if (resumptionInfo.isResumption) {
|
||||
log(`Detected session resumption in ClientHello without standard SNI`);
|
||||
|
||||
// Try to extract SNI from PSK extension
|
||||
const pskSni = this.extractSNIFromPSKExtension(processBuffer, logger);
|
||||
if (pskSni) {
|
||||
log(`Extracted SNI from PSK extension: ${pskSni}`);
|
||||
return pskSni;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// If cached SNI was provided, use it for application data packets
|
||||
if (cachedSni && TlsUtils.isTlsApplicationData(buffer)) {
|
||||
log(`Using provided cached SNI for application data: ${cachedSni}`);
|
||||
return cachedSni;
|
||||
}
|
||||
|
||||
return undefined;
|
||||
}
|
||||
|
||||
/**
|
||||
* Unified method for processing a TLS packet and extracting SNI.
|
||||
* Main entry point for SNI extraction that handles all edge cases.
|
||||
*
|
||||
* @param buffer The buffer containing TLS data
|
||||
* @param connectionInfo Connection tracking information
|
||||
* @param logger Optional logging function
|
||||
* @param cachedSni Optional previously cached SNI value
|
||||
* @returns The extracted server name or undefined
|
||||
*/
|
||||
public static processTlsPacket(
|
||||
buffer: Buffer,
|
||||
connectionInfo: ConnectionInfo,
|
||||
logger?: LoggerFunction,
|
||||
cachedSni?: string
|
||||
): string | undefined {
|
||||
const log = logger || (() => {});
|
||||
|
||||
// Add timestamp if not provided
|
||||
if (!connectionInfo.timestamp) {
|
||||
connectionInfo.timestamp = Date.now();
|
||||
}
|
||||
|
||||
// Check if this is a TLS handshake or application data
|
||||
if (!TlsUtils.isTlsHandshake(buffer) && !TlsUtils.isTlsApplicationData(buffer)) {
|
||||
log('Not a TLS handshake or application data packet');
|
||||
return undefined;
|
||||
}
|
||||
|
||||
// Create connection ID for tracking
|
||||
const connectionId = TlsUtils.createConnectionId(connectionInfo);
|
||||
log(`Processing TLS packet for connection ${connectionId}, buffer length: ${buffer.length}`);
|
||||
|
||||
// Handle application data with cached SNI (for connection racing)
|
||||
if (TlsUtils.isTlsApplicationData(buffer)) {
|
||||
// If explicit cachedSni was provided, use it
|
||||
if (cachedSni) {
|
||||
log(`Using provided cached SNI for application data: ${cachedSni}`);
|
||||
return cachedSni;
|
||||
}
|
||||
|
||||
log('Application data packet without cached SNI, cannot determine hostname');
|
||||
return undefined;
|
||||
}
|
||||
|
||||
// Enhanced session resumption detection
|
||||
if (TlsUtils.isClientHello(buffer)) {
|
||||
const resumptionInfo = ClientHelloParser.hasSessionResumption(buffer, logger);
|
||||
|
||||
if (resumptionInfo.isResumption) {
|
||||
log(`Session resumption detected in TLS packet`);
|
||||
|
||||
// Always try standard SNI extraction first
|
||||
const standardSni = this.extractSNI(buffer, logger);
|
||||
if (standardSni) {
|
||||
log(`Found standard SNI in session resumption: ${standardSni}`);
|
||||
return standardSni;
|
||||
}
|
||||
|
||||
// Enhanced session resumption SNI extraction
|
||||
// Try extracting from PSK identity
|
||||
const pskSni = this.extractSNIFromPSKExtension(buffer, logger);
|
||||
if (pskSni) {
|
||||
log(`Extracted SNI from PSK extension: ${pskSni}`);
|
||||
return pskSni;
|
||||
}
|
||||
|
||||
log(`Session resumption without extractable SNI`);
|
||||
}
|
||||
}
|
||||
|
||||
// For handshake messages, try the full extraction process
|
||||
const sni = this.extractSNIWithResumptionSupport(buffer, connectionInfo, logger);
|
||||
|
||||
if (sni) {
|
||||
log(`Successfully extracted SNI: ${sni}`);
|
||||
return sni;
|
||||
}
|
||||
|
||||
// If we couldn't extract an SNI, check if this is a valid ClientHello
|
||||
if (TlsUtils.isClientHello(buffer)) {
|
||||
log('Valid ClientHello detected, but no SNI extracted - might need more data');
|
||||
}
|
||||
|
||||
return undefined;
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user