smartproxy/ts/classes.snihandler.ts

836 lines
29 KiB
TypeScript

import { Buffer } from 'buffer';
/**
* SNI (Server Name Indication) handler for TLS connections.
* Provides robust extraction of SNI values from TLS ClientHello messages
* with support for fragmented packets, TLS 1.3 resumption, and Chrome-specific
* connection behaviors.
*/
export class SniHandler {
// TLS record types and constants
private static readonly TLS_HANDSHAKE_RECORD_TYPE = 22;
private static readonly TLS_APPLICATION_DATA_TYPE = 23; // TLS Application Data record type
private static readonly TLS_CLIENT_HELLO_HANDSHAKE_TYPE = 1;
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
private static readonly TLS_EARLY_DATA_EXTENSION_TYPE = 0x002A; // Early Data (0-RTT) extension
// Buffer for handling fragmented ClientHello messages
private static fragmentedBuffers: Map<string, Buffer> = new Map();
private static fragmentTimeout: number = 1000; // ms to wait for fragments before cleanup
/**
* Checks if a buffer contains a TLS handshake message (record type 22)
* @param buffer - The buffer to check
* @returns true if the buffer starts with a TLS handshake record type
*/
public static isTlsHandshake(buffer: Buffer): boolean {
return buffer.length > 0 && buffer[0] === this.TLS_HANDSHAKE_RECORD_TYPE;
}
/**
* Checks if a buffer contains TLS application data (record type 23)
* @param buffer - The buffer to check
* @returns true if the buffer starts with a TLS application data record type
*/
public static isTlsApplicationData(buffer: Buffer): boolean {
return buffer.length > 0 && buffer[0] === this.TLS_APPLICATION_DATA_TYPE;
}
/**
* Creates a connection ID based on source/destination information
* Used to track fragmented ClientHello messages across multiple packets
*
* @param connectionInfo - Object containing connection identifiers (IP/port)
* @returns A string ID for the connection
*/
public static createConnectionId(connectionInfo: {
sourceIp?: string;
sourcePort?: number;
destIp?: string;
destPort?: number;
}): string {
const { sourceIp, sourcePort, destIp, destPort } = connectionInfo;
return `${sourceIp}:${sourcePort}-${destIp}:${destPort}`;
}
/**
* Handles potential fragmented ClientHello messages by buffering and reassembling
* TLS record fragments that might span multiple TCP packets.
*
* @param buffer - The current buffer fragment
* @param connectionId - Unique identifier for the connection
* @param enableLogging - Whether to enable logging
* @returns A complete buffer if reassembly is successful, or undefined if more fragments are needed
*/
public static handleFragmentedClientHello(
buffer: Buffer,
connectionId: string,
enableLogging: boolean = false
): Buffer | undefined {
const log = (message: string) => {
if (enableLogging) {
console.log(`[SNI Fragment] ${message}`);
}
};
// Check if we've seen this connection before
if (!this.fragmentedBuffers.has(connectionId)) {
// New connection, start with this buffer
this.fragmentedBuffers.set(connectionId, buffer);
// Set timeout to clean up if we don't get a complete ClientHello
setTimeout(() => {
if (this.fragmentedBuffers.has(connectionId)) {
this.fragmentedBuffers.delete(connectionId);
log(`Connection ${connectionId} timed out waiting for complete ClientHello`);
}
}, this.fragmentTimeout);
// Evaluate if this buffer already contains a complete ClientHello
try {
if (buffer.length >= 5) {
const recordLength = (buffer[3] << 8) + buffer[4];
if (buffer.length >= recordLength + 5) {
log(`Initial buffer contains complete ClientHello, length: ${buffer.length}`);
return buffer;
}
}
} catch (e) {
log(`Error checking initial buffer completeness: ${e}`);
}
log(`Started buffering connection ${connectionId}, initial size: ${buffer.length}`);
return undefined; // Need more fragments
} else {
// Existing connection, append this buffer
const existingBuffer = this.fragmentedBuffers.get(connectionId)!;
const newBuffer = Buffer.concat([existingBuffer, buffer]);
this.fragmentedBuffers.set(connectionId, newBuffer);
log(`Appended to buffer for ${connectionId}, new size: ${newBuffer.length}`);
// Check if we now have a complete ClientHello
try {
if (newBuffer.length >= 5) {
const recordLength = (newBuffer[3] << 8) + newBuffer[4];
if (newBuffer.length >= recordLength + 5) {
log(`Assembled complete ClientHello, length: ${newBuffer.length}`);
// Complete message received, remove from tracking
this.fragmentedBuffers.delete(connectionId);
return newBuffer;
}
}
} catch (e) {
log(`Error checking reassembled buffer completeness: ${e}`);
}
return undefined; // Still need more fragments
}
}
/**
* Checks if a buffer contains a TLS ClientHello message
* @param buffer - The buffer to check
* @returns true if the buffer appears to be a ClientHello message
*/
public static isClientHello(buffer: Buffer): boolean {
// Minimum ClientHello size (TLS record header + handshake header)
if (buffer.length < 9) {
return false;
}
// Check record type (must be TLS_HANDSHAKE_RECORD_TYPE)
if (buffer[0] !== this.TLS_HANDSHAKE_RECORD_TYPE) {
return false;
}
// Skip version and length in TLS record header (5 bytes total)
// Check handshake type at byte 5 (must be CLIENT_HELLO)
return buffer[5] === this.TLS_CLIENT_HELLO_HANDSHAKE_TYPE;
}
/**
* Extracts the SNI (Server Name Indication) from a TLS ClientHello message.
* Implements robust parsing with support for session resumption edge cases.
*
* @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 extractSNI(buffer: Buffer, enableLogging: boolean = false): string | undefined {
// Logging helper
const log = (message: string) => {
if (enableLogging) {
console.log(`[SNI Extraction] ${message}`);
}
};
try {
// Buffer must be at least 5 bytes (TLS record header)
if (buffer.length < 5) {
log('Buffer too small for TLS record header');
return undefined;
}
// Check record type (must be TLS_HANDSHAKE_RECORD_TYPE = 22)
if (buffer[0] !== this.TLS_HANDSHAKE_RECORD_TYPE) {
log(`Not a TLS handshake record: ${buffer[0]}`);
return undefined;
}
// Check TLS version
const majorVersion = buffer[1];
const minorVersion = buffer[2];
log(`TLS version: ${majorVersion}.${minorVersion}`);
// Parse record length (bytes 3-4, big-endian)
const recordLength = (buffer[3] << 8) + buffer[4];
log(`Record length: ${recordLength}`);
// Validate record length against buffer size
if (buffer.length < recordLength + 5) {
log('Buffer smaller than expected record length');
return undefined;
}
// Start of handshake message in the buffer
let pos = 5;
// Check handshake type (must be CLIENT_HELLO = 1)
if (buffer[pos] !== this.TLS_CLIENT_HELLO_HANDSHAKE_TYPE) {
log(`Not a ClientHello message: ${buffer[pos]}`);
return undefined;
}
// Skip handshake type (1 byte)
pos += 1;
// Parse handshake length (3 bytes, big-endian)
const handshakeLength = (buffer[pos] << 16) + (buffer[pos + 1] << 8) + buffer[pos + 2];
log(`Handshake length: ${handshakeLength}`);
// Skip handshake length (3 bytes)
pos += 3;
// Check client version (2 bytes)
const clientMajorVersion = buffer[pos];
const clientMinorVersion = buffer[pos + 1];
log(`Client version: ${clientMajorVersion}.${clientMinorVersion}`);
// Skip client version (2 bytes)
pos += 2;
// Skip client random (32 bytes)
pos += 32;
// Parse session ID
if (pos + 1 > buffer.length) {
log('Buffer too small for session ID length');
return undefined;
}
const sessionIdLength = buffer[pos];
log(`Session ID length: ${sessionIdLength}`);
// Skip session ID length (1 byte) and session ID
pos += 1 + sessionIdLength;
// Check if we have enough bytes left
if (pos + 2 > buffer.length) {
log('Buffer too small for cipher suites length');
return undefined;
}
// Parse cipher suites length (2 bytes, big-endian)
const cipherSuitesLength = (buffer[pos] << 8) + buffer[pos + 1];
log(`Cipher suites length: ${cipherSuitesLength}`);
// Skip cipher suites length (2 bytes) and cipher suites
pos += 2 + cipherSuitesLength;
// Check if we have enough bytes left
if (pos + 1 > buffer.length) {
log('Buffer too small for compression methods length');
return undefined;
}
// Parse compression methods length (1 byte)
const compressionMethodsLength = buffer[pos];
log(`Compression methods length: ${compressionMethodsLength}`);
// Skip compression methods length (1 byte) and compression methods
pos += 1 + compressionMethodsLength;
// Check if we have enough bytes for extensions length
if (pos + 2 > buffer.length) {
log('No extensions present or buffer too small');
return undefined;
}
// Parse extensions length (2 bytes, big-endian)
const extensionsLength = (buffer[pos] << 8) + buffer[pos + 1];
log(`Extensions length: ${extensionsLength}`);
// Skip extensions length (2 bytes)
pos += 2;
// Extensions end position
const extensionsEnd = pos + extensionsLength;
// Check if extensions length is valid
if (extensionsEnd > buffer.length) {
log('Extensions length exceeds buffer size');
return undefined;
}
// Track if we found session tickets (for improved resumption handling)
let hasSessionTicket = false;
let hasPskExtension = false;
// Iterate through extensions
while (pos + 4 <= extensionsEnd) {
// Parse extension type (2 bytes, big-endian)
const extensionType = (buffer[pos] << 8) + buffer[pos + 1];
log(`Extension type: 0x${extensionType.toString(16).padStart(4, '0')}`);
// Skip extension type (2 bytes)
pos += 2;
// Parse extension length (2 bytes, big-endian)
const extensionLength = (buffer[pos] << 8) + buffer[pos + 1];
log(`Extension length: ${extensionLength}`);
// Skip extension length (2 bytes)
pos += 2;
// Check if this is the SNI extension
if (extensionType === this.TLS_SNI_EXTENSION_TYPE) {
log('Found SNI extension');
// Ensure we have enough bytes for the server name list
if (pos + 2 > extensionsEnd) {
log('Extension too small for server name list length');
pos += extensionLength; // Skip this extension
continue;
}
// Parse server name list length (2 bytes, big-endian)
const serverNameListLength = (buffer[pos] << 8) + buffer[pos + 1];
log(`Server name list length: ${serverNameListLength}`);
// Skip server name list length (2 bytes)
pos += 2;
// Ensure server name list length is valid
if (pos + serverNameListLength > extensionsEnd) {
log('Server name list length exceeds extension size');
break; // Exit the loop, extension parsing is broken
}
// End position of server name list
const serverNameListEnd = pos + serverNameListLength;
// Iterate through server names
while (pos + 3 <= serverNameListEnd) {
// Check name type (must be HOST_NAME_TYPE = 0 for hostname)
const nameType = buffer[pos];
log(`Name type: ${nameType}`);
if (nameType !== this.TLS_SNI_HOST_NAME_TYPE) {
log(`Unsupported name type: ${nameType}`);
pos += 1; // Skip name type (1 byte)
// Skip name length (2 bytes) and name data
if (pos + 2 <= serverNameListEnd) {
const nameLength = (buffer[pos] << 8) + buffer[pos + 1];
pos += 2 + nameLength;
} else {
log('Invalid server name entry');
break;
}
continue;
}
// Skip name type (1 byte)
pos += 1;
// Ensure we have enough bytes for name length
if (pos + 2 > serverNameListEnd) {
log('Server name entry too small for name length');
break;
}
// Parse name length (2 bytes, big-endian)
const nameLength = (buffer[pos] << 8) + buffer[pos + 1];
log(`Name length: ${nameLength}`);
// Skip name length (2 bytes)
pos += 2;
// Ensure we have enough bytes for the name
if (pos + nameLength > serverNameListEnd) {
log('Name length exceeds server name list size');
break;
}
// Extract server name (hostname)
const serverName = buffer.slice(pos, pos + nameLength).toString('utf8');
log(`Extracted server name: ${serverName}`);
return serverName;
}
} else if (extensionType === this.TLS_SESSION_TICKET_EXTENSION_TYPE) {
// If we encounter a session ticket extension, mark it for later
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 session resumption indicators but no SNI
if (hasSessionTicket || hasPskExtension) {
log('Session resumption indicators present but no SNI found');
}
log('No SNI extension found in ClientHello');
return undefined;
} catch (error) {
log(`Error parsing 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 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;
}
}
/**
* 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;
}
}