SNISSLExplorer.java
/*
* JBoss, Home of Professional Open Source.
* Copyright 2018 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.undertow.protocols.ssl;
import java.nio.ByteBuffer;
import java.nio.BufferUnderflowException;
import java.io.IOException;
import javax.net.ssl.SNIHostName;
import javax.net.ssl.SNIServerName;
import javax.net.ssl.SSLException;
import javax.net.ssl.StandardConstants;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import io.undertow.UndertowMessages;
/**
* Instances of this class acts as an explorer of the network data of an
* SSL/TLS connection.
*/
final class SNISSLExplorer {
// Private constructor prevents construction outside this class.
private SNISSLExplorer() {
}
/**
* The header size of TLS/SSL records.
* <P>
* The value of this constant is {@value}.
*/
public static final int RECORD_HEADER_SIZE = 0x05;
/**
* Returns the required number of bytes in the {@code source}
* {@link ByteBuffer} necessary to explore SSL/TLS connection.
* <P>
* This method tries to parse as few bytes as possible from
* {@code source} byte buffer to get the length of an
* SSL/TLS record.
* <P>
* This method accesses the {@code source} parameter in read-only
* mode, and does not update the buffer's properties such as capacity,
* limit, position, and mark values.
*
* @param source
* a {@link ByteBuffer} containing
* inbound or outbound network data for an SSL/TLS connection.
* @throws BufferUnderflowException if less than {@code RECORD_HEADER_SIZE}
* bytes remaining in {@code source}
* @return the required size in byte to explore an SSL/TLS connection
*/
public static int getRequiredSize(ByteBuffer source) {
ByteBuffer input = source.duplicate();
// Do we have a complete header?
if (input.remaining() < RECORD_HEADER_SIZE) {
throw new BufferUnderflowException();
}
// Is it a handshake message?
byte firstByte = input.get();
input.get();
byte thirdByte = input.get();
if ((firstByte & 0x80) != 0 && thirdByte == 0x01) {
return RECORD_HEADER_SIZE; // Only need the header fields
} else {
return ((input.get() & 0xFF) << 8 | input.get() & 0xFF) + 5;
}
}
/**
* Returns the required number of bytes in the {@code source} byte array
* necessary to explore SSL/TLS connection.
* <P>
* This method tries to parse as few bytes as possible from
* {@code source} byte array to get the length of an
* SSL/TLS record.
*
* @param source
* a byte array containing inbound or outbound network data for
* an SSL/TLS connection.
* @param offset
* the start offset in array {@code source} at which the
* network data is read from.
* @param length
* the maximum number of bytes to read.
*
* @throws BufferUnderflowException if less than {@code RECORD_HEADER_SIZE}
* bytes remaining in {@code source}
* @return the required size in byte to explore an SSL/TLS connection
*/
public static int getRequiredSize(byte[] source,
int offset, int length) throws IOException {
ByteBuffer byteBuffer =
ByteBuffer.wrap(source, offset, length).asReadOnlyBuffer();
return getRequiredSize(byteBuffer);
}
/**
* Launch and explore the security capabilities from byte buffer.
* <P>
* This method tries to parse as few records as possible from
* {@code source} byte buffer to get the capabilities
* of an SSL/TLS connection.
* <P>
* Please NOTE that this method must be called before any handshaking
* occurs. The behavior of this method is not defined in this release
* if the handshake has begun, or has completed.
* <P>
* This method accesses the {@code source} parameter in read-only
* mode, and does not update the buffer's properties such as capacity,
* limit, position, and mark values.
*
* @param source
* a {@link ByteBuffer} containing
* inbound or outbound network data for an SSL/TLS connection.
*
* @throws IOException on network data error
* @throws BufferUnderflowException if not enough source bytes available
* to make a complete exploration.
*
* @return the explored capabilities of the SSL/TLS
* connection
*/
public static List<SNIServerName> explore(ByteBuffer source)
throws SSLException {
ByteBuffer input = source.duplicate();
// Do we have a complete header?
if (input.remaining() < RECORD_HEADER_SIZE) {
throw new BufferUnderflowException();
}
// Is it a handshake message?
byte firstByte = input.get();
byte secondByte = input.get();
byte thirdByte = input.get();
if ((firstByte & 0x80) != 0 && thirdByte == 0x01) {
// looks like a V2ClientHello
return Collections.emptyList();
} else if (firstByte == 22) { // 22: handshake record
return exploreTLSRecord(input,
firstByte, secondByte, thirdByte);
} else {
throw UndertowMessages.MESSAGES.notHandshakeRecord();
}
}
/**
* Launch and explore the security capabilities from byte array.
* <P>
* Please NOTE that this method must be called before any handshaking
* occurs. The behavior of this method is not defined in this release
* if the handshake has begun, or has completed. Once handshake has
* begun, or has completed, the security capabilities can not and
* should not be launched with this method.
*
* @param source
* a byte array containing inbound or outbound network data for
* an SSL/TLS connection.
* @param offset
* the start offset in array {@code source} at which the
* network data is read from.
* @param length
* the maximum number of bytes to read.
*
* @throws IOException on network data error
* @throws BufferUnderflowException if not enough source bytes available
* to make a complete exploration.
* @return the explored capabilities of the SSL/TLS
* connection
*
* @see #explore(ByteBuffer)
*/
public static List<SNIServerName> explore(byte[] source,
int offset, int length) throws IOException {
ByteBuffer byteBuffer =
ByteBuffer.wrap(source, offset, length).asReadOnlyBuffer();
return explore(byteBuffer);
}
/*
* struct {
* uint8 major;
* uint8 minor;
* } ProtocolVersion;
*
* enum {
* change_cipher_spec(20), alert(21), handshake(22),
* application_data(23), (255)
* } ContentType;
*
* struct {
* ContentType type;
* ProtocolVersion version;
* uint16 length;
* opaque fragment[TLSPlaintext.length];
* } TLSPlaintext;
*/
private static List<SNIServerName> exploreTLSRecord(
ByteBuffer input, byte firstByte, byte secondByte,
byte thirdByte) throws SSLException {
// Is it a handshake message?
if (firstByte != 22) { // 22: handshake record
throw UndertowMessages.MESSAGES.notHandshakeRecord();
}
// Is there enough data for a full record?
int recordLength = getInt16(input);
if (recordLength > input.remaining()) {
throw new BufferUnderflowException();
}
// We have already had enough source bytes.
try {
return exploreHandshake(input,
secondByte, thirdByte, recordLength);
} catch (BufferUnderflowException ignored) {
throw UndertowMessages.MESSAGES.invalidHandshakeRecord();
}
}
/*
* enum {
* hello_request(0), client_hello(1), server_hello(2),
* certificate(11), server_key_exchange (12),
* certificate_request(13), server_hello_done(14),
* certificate_verify(15), client_key_exchange(16),
* finished(20)
* (255)
* } HandshakeType;
*
* struct {
* HandshakeType msg_type;
* uint24 length;
* select (HandshakeType) {
* case hello_request: HelloRequest;
* case client_hello: ClientHello;
* case server_hello: ServerHello;
* case certificate: Certificate;
* case server_key_exchange: ServerKeyExchange;
* case certificate_request: CertificateRequest;
* case server_hello_done: ServerHelloDone;
* case certificate_verify: CertificateVerify;
* case client_key_exchange: ClientKeyExchange;
* case finished: Finished;
* } body;
* } Handshake;
*/
private static List<SNIServerName> exploreHandshake(
ByteBuffer input, byte recordMajorVersion,
byte recordMinorVersion, int recordLength) throws SSLException {
// What is the handshake type?
byte handshakeType = input.get();
if (handshakeType != 0x01) { // 0x01: client_hello message
throw UndertowMessages.MESSAGES.expectedClientHello();
}
// What is the handshake body length?
int handshakeLength = getInt24(input);
// Theoretically, a single handshake message might span multiple
// records, but in practice this does not occur.
if (handshakeLength > recordLength - 4) { // 4: handshake header size
throw UndertowMessages.MESSAGES.multiRecordSSLHandshake();
}
input = input.duplicate();
input.limit(handshakeLength + input.position());
return exploreClientHello(input,
recordMajorVersion, recordMinorVersion);
}
/*
* struct {
* uint32 gmt_unix_time;
* opaque random_bytes[28];
* } Random;
*
* opaque SessionID<0..32>;
*
* uint8 CipherSuite[2];
*
* enum { null(0), (255) } CompressionMethod;
*
* struct {
* ProtocolVersion client_version;
* Random random;
* SessionID session_id;
* CipherSuite cipher_suites<2..2^16-2>;
* CompressionMethod compression_methods<1..2^8-1>;
* select (extensions_present) {
* case false:
* struct {};
* case true:
* Extension extensions<0..2^16-1>;
* };
* } ClientHello;
*/
private static List<SNIServerName> exploreClientHello(
ByteBuffer input,
byte recordMajorVersion,
byte recordMinorVersion) throws SSLException {
ExtensionInfo info = null;
// client version
input.get(); //helloMajorVersion
input.get(); //helloMinorVersion
// ignore random
int position = input.position();
input.position(position + 32); // 32: the length of Random
// ignore session id
ignoreByteVector8(input);
// ignore cipher_suites
int csLen = getInt16(input);
while (csLen > 0) {
getInt8(input);
getInt8(input);
csLen -= 2;
}
// ignore compression methods
ignoreByteVector8(input);
if (input.remaining() > 0) {
info = exploreExtensions(input);
}
final List<SNIServerName> snList = info != null ? info.sni : Collections.emptyList();
return snList;
}
/*
* struct {
* ExtensionType extension_type;
* opaque extension_data<0..2^16-1>;
* } Extension;
*
* enum {
* server_name(0), max_fragment_length(1),
* client_certificate_url(2), trusted_ca_keys(3),
* truncated_hmac(4), status_request(5), (65535)
* } ExtensionType;
*/
private static ExtensionInfo exploreExtensions(ByteBuffer input)
throws SSLException {
List<SNIServerName> sni = Collections.emptyList();
List<String> alpn = Collections.emptyList();
int length = getInt16(input); // length of extensions
while (length > 0) {
int extType = getInt16(input); // extension type
int extLen = getInt16(input); // length of extension data
if (extType == 0x00) { // 0x00: type of server name indication
sni = exploreSNIExt(input, extLen);
} else if (extType == 0x10) { // 0x10: type of alpn
alpn = exploreALPN(input, extLen);
} else { // ignore other extensions
ignoreByteVector(input, extLen);
}
length -= extLen + 4;
}
return new ExtensionInfo(sni, alpn);
}
/*
* opaque ProtocolName<1..2^8-1>;
*
* struct {
* ProtocolName protocol_name_list<2..2^16-1>
* } ProtocolNameList;
*
*/
private static List<String> exploreALPN(ByteBuffer input,
int extLen) throws SSLException {
final ArrayList<String> strings = new ArrayList<>();
int rem = extLen;
if (extLen >= 2) {
int listLen = getInt16(input);
if (listLen == 0 || listLen + 2 != extLen) {
throw UndertowMessages.MESSAGES.invalidTlsExt();
}
rem -= 2;
while (rem > 0) {
int len = getInt8(input);
if (len > rem) {
throw UndertowMessages.MESSAGES.notEnoughData();
}
byte[] b = new byte[len];
input.get(b);
strings.add(new String(b, StandardCharsets.UTF_8));
rem -= len + 1;
}
}
return strings.isEmpty() ? Collections.emptyList() : strings;
}
/*
* struct {
* NameType name_type;
* select (name_type) {
* case host_name: HostName;
* } name;
* } ServerName;
*
* enum {
* host_name(0), (255)
* } NameType;
*
* opaque HostName<1..2^16-1>;
*
* struct {
* ServerName server_name_list<1..2^16-1>
* } ServerNameList;
*/
private static List<SNIServerName> exploreSNIExt(ByteBuffer input,
int extLen) throws SSLException {
Map<Integer, SNIServerName> sniMap = new LinkedHashMap<>();
int remains = extLen;
if (extLen >= 2) { // "server_name" extension in ClientHello
int listLen = getInt16(input); // length of server_name_list
if (listLen == 0 || listLen + 2 != extLen) {
throw UndertowMessages.MESSAGES.invalidTlsExt();
}
remains -= 2; // 0x02: the length field of server_name_list
while (remains > 0) {
int code = getInt8(input); // name_type
int snLen = getInt16(input); // length field of server name
if (snLen > remains) {
throw UndertowMessages.MESSAGES.notEnoughData();
}
byte[] encoded = new byte[snLen];
input.get(encoded);
SNIServerName serverName;
switch (code) {
case StandardConstants.SNI_HOST_NAME:
if (encoded.length == 0) {
throw UndertowMessages.MESSAGES.emptyHostNameSni();
}
serverName = new SNIHostName(encoded);
break;
default:
serverName = new UnknownServerName(code, encoded);
}
// check for duplicated server name type
if (sniMap.put(serverName.getType(), serverName) != null) {
throw UndertowMessages.MESSAGES.duplicatedSniServerName(serverName.getType());
}
remains -= encoded.length + 3; // NameType: 1 byte
// HostName length: 2 bytes
}
} else if (extLen == 0) { // "server_name" extension in ServerHello
throw UndertowMessages.MESSAGES.invalidTlsExt();
}
if (remains != 0) {
throw UndertowMessages.MESSAGES.invalidTlsExt();
}
return Collections.unmodifiableList(new ArrayList<>(sniMap.values()));
}
private static int getInt8(ByteBuffer input) {
return input.get();
}
private static int getInt16(ByteBuffer input) {
return (input.get() & 0xFF) << 8 | input.get() & 0xFF;
}
private static int getInt24(ByteBuffer input) {
return (input.get() & 0xFF) << 16 | (input.get() & 0xFF) << 8 |
input.get() & 0xFF;
}
private static void ignoreByteVector8(ByteBuffer input) {
ignoreByteVector(input, getInt8(input));
}
private static void ignoreByteVector(ByteBuffer input, int length) {
if (length != 0) {
int position = input.position();
input.position(position + length);
}
}
static final class UnknownServerName extends SNIServerName {
UnknownServerName(int code, byte[] encoded) {
super(code, encoded);
}
}
static final class ExtensionInfo {
final List<SNIServerName> sni;
final List<String> alpn;
ExtensionInfo(final List<SNIServerName> sni, final List<String> alpn) {
this.sni = sni;
this.alpn = alpn;
}
}
}