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/*
* Copyright (c) 2020, Ali Mohammad Pur <mpfard@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <AK/Endian.h>
#include <AK/Random.h>
#include <LibCore/Timer.h>
#include <LibCrypto/ASN1/DER.h>
#include <LibCrypto/PK/Code/EMSA_PSS.h>
#include <LibTLS/TLSv12.h>
namespace TLS {
ssize_t TLSv12::handle_server_hello(ReadonlyBytes buffer, WritePacketStage& write_packets)
{
write_packets = WritePacketStage::Initial;
if (m_context.connection_status != ConnectionStatus::Disconnected && m_context.connection_status != ConnectionStatus::Renegotiating) {
dbgln("unexpected hello message");
return (i8)Error::UnexpectedMessage;
}
ssize_t res = 0;
size_t min_hello_size = 41;
if (min_hello_size > buffer.size()) {
dbgln("need more data");
return (i8)Error::NeedMoreData;
}
size_t following_bytes = buffer[0] * 0x10000 + buffer[1] * 0x100 + buffer[2];
res += 3;
if (buffer.size() - res < following_bytes) {
dbgln("not enough data after header: {} < {}", buffer.size() - res, following_bytes);
return (i8)Error::NeedMoreData;
}
if (buffer.size() - res < 2) {
dbgln("not enough data for version");
return (i8)Error::NeedMoreData;
}
auto version = static_cast<Version>(AK::convert_between_host_and_network_endian(ByteReader::load16(buffer.offset_pointer(res))));
res += 2;
if (!supports_version(version))
return (i8)Error::NotSafe;
memcpy(m_context.remote_random, buffer.offset_pointer(res), sizeof(m_context.remote_random));
res += sizeof(m_context.remote_random);
u8 session_length = buffer[res++];
if (buffer.size() - res < session_length) {
dbgln("not enough data for session id");
return (i8)Error::NeedMoreData;
}
if (session_length && session_length <= 32) {
memcpy(m_context.session_id, buffer.offset_pointer(res), session_length);
m_context.session_id_size = session_length;
if constexpr (TLS_DEBUG) {
dbgln("Remote session ID:");
print_buffer(ReadonlyBytes { m_context.session_id, session_length });
}
} else {
m_context.session_id_size = 0;
}
res += session_length;
if (buffer.size() - res < 2) {
dbgln("not enough data for cipher suite listing");
return (i8)Error::NeedMoreData;
}
auto cipher = static_cast<CipherSuite>(AK::convert_between_host_and_network_endian(ByteReader::load16(buffer.offset_pointer(res))));
res += 2;
if (!supports_cipher(cipher)) {
m_context.cipher = CipherSuite::Invalid;
dbgln("No supported cipher could be agreed upon");
return (i8)Error::NoCommonCipher;
}
m_context.cipher = cipher;
dbgln_if(TLS_DEBUG, "Cipher: {}", (u16)cipher);
// Simplification: We only support handshake hash functions via HMAC
m_context.handshake_hash.initialize(hmac_hash());
// Compression method
if (buffer.size() - res < 1)
return (i8)Error::NeedMoreData;
u8 compression = buffer[res++];
if (compression != 0)
return (i8)Error::CompressionNotSupported;
if (m_context.connection_status != ConnectionStatus::Renegotiating)
m_context.connection_status = ConnectionStatus::Negotiating;
if (m_context.is_server) {
dbgln("unsupported: server mode");
write_packets = WritePacketStage::ServerHandshake;
}
// Presence of extensions is determined by availability of bytes after compression_method
if (buffer.size() - res >= 2) {
auto extensions_bytes_total = AK::convert_between_host_and_network_endian(ByteReader::load16(buffer.offset_pointer(res += 2)));
dbgln_if(TLS_DEBUG, "Extensions bytes total: {}", extensions_bytes_total);
}
while (buffer.size() - res >= 4) {
auto extension_type = (HandshakeExtension)AK::convert_between_host_and_network_endian(ByteReader::load16(buffer.offset_pointer(res)));
res += 2;
u16 extension_length = AK::convert_between_host_and_network_endian(ByteReader::load16(buffer.offset_pointer(res)));
res += 2;
dbgln_if(TLS_DEBUG, "Extension {} with length {}", (u16)extension_type, extension_length);
if (buffer.size() - res < extension_length)
return (i8)Error::NeedMoreData;
if (extension_type == HandshakeExtension::ServerName) {
// RFC6066 section 3: SNI extension_data can be empty in the server hello
if (extension_length > 0) {
// ServerNameList total size
if (buffer.size() - res < 2)
return (i8)Error::NeedMoreData;
auto sni_name_list_bytes = AK::convert_between_host_and_network_endian(ByteReader::load16(buffer.offset_pointer(res += 2)));
dbgln_if(TLS_DEBUG, "SNI: expecting ServerNameList of {} bytes", sni_name_list_bytes);
// Exactly one ServerName should be present
if (buffer.size() - res < 3)
return (i8)Error::NeedMoreData;
auto sni_name_type = (NameType)(*(const u8*)buffer.offset_pointer(res++));
auto sni_name_length = AK::convert_between_host_and_network_endian(ByteReader::load16(buffer.offset_pointer(res += 2)));
if (sni_name_type != NameType::HostName)
return (i8)Error::NotUnderstood;
if (sizeof(sni_name_type) + sizeof(sni_name_length) + sni_name_length != sni_name_list_bytes)
return (i8)Error::BrokenPacket;
// Read out the host_name
if (buffer.size() - res < sni_name_length)
return (i8)Error::NeedMoreData;
m_context.extensions.SNI = String { (const char*)buffer.offset_pointer(res), sni_name_length };
res += sni_name_length;
dbgln("SNI host_name: {}", m_context.extensions.SNI);
}
} else if (extension_type == HandshakeExtension::ApplicationLayerProtocolNegotiation && m_context.alpn.size()) {
if (buffer.size() - res > 2) {
auto alpn_length = AK::convert_between_host_and_network_endian(ByteReader::load16(buffer.offset_pointer(res)));
if (alpn_length && alpn_length <= extension_length - 2) {
const u8* alpn = buffer.offset_pointer(res + 2);
size_t alpn_position = 0;
while (alpn_position < alpn_length) {
u8 alpn_size = alpn[alpn_position++];
if (alpn_size + alpn_position >= extension_length)
break;
String alpn_str { (const char*)alpn + alpn_position, alpn_length };
if (alpn_size && m_context.alpn.contains_slow(alpn_str)) {
m_context.negotiated_alpn = alpn_str;
dbgln("negotiated alpn: {}", alpn_str);
break;
}
alpn_position += alpn_length;
if (!m_context.is_server) // server hello must contain one ALPN
break;
}
}
}
res += extension_length;
} else if (extension_type == HandshakeExtension::SignatureAlgorithms) {
dbgln("supported signatures: ");
print_buffer(buffer.slice(res, extension_length));
res += extension_length;
// FIXME: what are we supposed to do here?
} else {
dbgln("Encountered unknown extension {} with length {}", (u16)extension_type, extension_length);
res += extension_length;
}
}
return res;
}
ssize_t TLSv12::handle_server_hello_done(ReadonlyBytes buffer)
{
if (buffer.size() < 3)
return (i8)Error::NeedMoreData;
size_t size = buffer[0] * 0x10000 + buffer[1] * 0x100 + buffer[2];
if (buffer.size() - 3 < size)
return (i8)Error::NeedMoreData;
return size + 3;
}
ByteBuffer TLSv12::build_server_key_exchange()
{
dbgln("FIXME: build_server_key_exchange");
return {};
}
ssize_t TLSv12::handle_server_key_exchange(ReadonlyBytes)
{
switch (get_key_exchange_algorithm(m_context.cipher)) {
case KeyExchangeAlgorithm::RSA:
case KeyExchangeAlgorithm::DH_DSS:
case KeyExchangeAlgorithm::DH_RSA:
// RFC 5246 section 7.4.3. Server Key Exchange Message
// It is not legal to send the server key exchange message for RSA, DH_DSS, DH_RSA
dbgln("Server key exchange received for RSA, DH_DSS or DH_RSA is not legal");
return (i8)Error::UnexpectedMessage;
case KeyExchangeAlgorithm::DHE_DSS:
dbgln("Server key exchange for DHE_DSS is not implemented");
TODO();
break;
case KeyExchangeAlgorithm::DHE_RSA:
dbgln("Server key exchange for DHE_RSA is not implemented");
TODO();
break;
case KeyExchangeAlgorithm::DH_anon:
dbgln("Server key exchange for DH_anon is not implemented");
TODO();
break;
case KeyExchangeAlgorithm::ECDHE_RSA:
case KeyExchangeAlgorithm::ECDH_ECDSA:
case KeyExchangeAlgorithm::ECDH_RSA:
case KeyExchangeAlgorithm::ECDHE_ECDSA:
case KeyExchangeAlgorithm::ECDH_anon:
dbgln("Server key exchange for ECDHE algorithms is not implemented");
TODO();
break;
default:
dbgln("Unknonwn server key exchange algorithm");
VERIFY_NOT_REACHED();
break;
}
return 0;
}
}
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