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https://github.com/RGBCube/serenity
synced 2025-07-26 04:47:34 +00:00
LibTLS: Support empty SNI data in ServerHello
According to RFC6066, empty extension_data for an SNI extension is absolutely one of the possibilities - so let's support this instead of spamming the debug log.
This commit is contained in:
Jelle Raaijmakers
Andreas Kling
parent
48eb58230b
commit
7d5995f08c
2 changed files with 72 additions and 61 deletions
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@ -117,27 +117,24 @@ ssize_t TLSv12::handle_hello(ReadonlyBytes buffer, WritePacketStage& write_packe
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// The handshake hash function is _always_ SHA256
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m_context.handshake_hash.initialize(Crypto::Hash::HashKind::SHA256);
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if (buffer.size() - res < 1) {
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dbgln("not enough data for compression spec");
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// Compression method
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if (buffer.size() - res < 1)
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return (i8)Error::NeedMoreData;
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}
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u8 compression = buffer[res++];
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if (compression != 0) {
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dbgln("Server told us to compress, we will not!");
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if (compression != 0)
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return (i8)Error::CompressionNotSupported;
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if (m_context.connection_status != ConnectionStatus::Renegotiating)
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m_context.connection_status = ConnectionStatus::Negotiating;
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if (m_context.is_server) {
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dbgln("unsupported: server mode");
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write_packets = WritePacketStage::ServerHandshake;
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}
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if (res > 0) {
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if (m_context.connection_status != ConnectionStatus::Renegotiating)
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m_context.connection_status = ConnectionStatus::Negotiating;
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if (m_context.is_server) {
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dbgln("unsupported: server mode");
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write_packets = WritePacketStage::ServerHandshake;
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}
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}
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if (res > 2) {
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res += 2;
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// Presence of extensions is determined by availability of bytes after compression_method
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if (buffer.size() - res >= 2) {
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auto extensions_bytes_total = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res += 2));
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dbgln_if(TLS_DEBUG, "Extensions bytes total: {}", extensions_bytes_total);
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}
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while ((ssize_t)buffer.size() - res >= 4) {
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@ -146,60 +143,70 @@ ssize_t TLSv12::handle_hello(ReadonlyBytes buffer, WritePacketStage& write_packe
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u16 extension_length = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res));
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res += 2;
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dbgln_if(TLS_DEBUG, "extension {} with length {}", (u16)extension_type, extension_length);
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dbgln_if(TLS_DEBUG, "Extension {} with length {}", (u16)extension_type, extension_length);
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if (extension_length) {
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if (buffer.size() - res < extension_length) {
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dbgln("not enough data for extension");
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return (i8)Error::NeedMoreData;
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}
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if (buffer.size() - res < extension_length)
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return (i8)Error::NeedMoreData;
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dbgln("Encountered extension {} with length {}", (u16)extension_type, extension_length);
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// SNI
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if (extension_type == HandshakeExtension::ServerName) {
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u16 sni_host_length = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res + 3));
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if (buffer.size() - res - 5 < sni_host_length) {
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dbgln("Not enough data for sni {} < {}", (buffer.size() - res - 5), sni_host_length);
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if (extension_type == HandshakeExtension::ServerName) {
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// RFC6066 section 3: SNI extension_data can be empty in the server hello
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if (extension_length > 0) {
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// ServerNameList total size
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if (buffer.size() - res < 2)
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return (i8)Error::NeedMoreData;
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}
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auto sni_name_list_bytes = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res += 2));
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dbgln_if(TLS_DEBUG, "SNI: expecting ServerNameList of {} bytes", sni_name_list_bytes);
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if (sni_host_length) {
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m_context.extensions.SNI = String { (const char*)buffer.offset_pointer(res + 5), sni_host_length };
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dbgln("server name indicator: {}", m_context.extensions.SNI);
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}
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} else if (extension_type == HandshakeExtension::ApplicationLayerProtocolNegotiation && m_context.alpn.size()) {
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if (buffer.size() - res > 2) {
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auto alpn_length = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res));
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if (alpn_length && alpn_length <= extension_length - 2) {
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const u8* alpn = buffer.offset_pointer(res + 2);
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size_t alpn_position = 0;
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while (alpn_position < alpn_length) {
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u8 alpn_size = alpn[alpn_position++];
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if (alpn_size + alpn_position >= extension_length)
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break;
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String alpn_str { (const char*)alpn + alpn_position, alpn_length };
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if (alpn_size && m_context.alpn.contains_slow(alpn_str)) {
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m_context.negotiated_alpn = alpn_str;
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dbgln("negotiated alpn: {}", alpn_str);
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break;
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}
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alpn_position += alpn_length;
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if (!m_context.is_server) // server hello must contain one ALPN
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break;
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// Exactly one ServerName should be present
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if (buffer.size() - res < 3)
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return (i8)Error::NeedMoreData;
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auto sni_name_type = (NameType)(*(const u8*)buffer.offset_pointer(res++));
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auto sni_name_length = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res += 2));
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if (sni_name_type != NameType::HostName)
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return (i8)Error::NotUnderstood;
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if (sizeof(sni_name_type) + sizeof(sni_name_length) + sni_name_length != sni_name_list_bytes)
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return (i8)Error::BrokenPacket;
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// Read out the host_name
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if (buffer.size() - res < sni_name_length)
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return (i8)Error::NeedMoreData;
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m_context.extensions.SNI = String { (const char*)buffer.offset_pointer(res), sni_name_length };
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res += sni_name_length;
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dbgln("SNI host_name: {}", m_context.extensions.SNI);
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}
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} else if (extension_type == HandshakeExtension::ApplicationLayerProtocolNegotiation && m_context.alpn.size()) {
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if (buffer.size() - res > 2) {
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auto alpn_length = AK::convert_between_host_and_network_endian(*(const u16*)buffer.offset_pointer(res));
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if (alpn_length && alpn_length <= extension_length - 2) {
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const u8* alpn = buffer.offset_pointer(res + 2);
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size_t alpn_position = 0;
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while (alpn_position < alpn_length) {
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u8 alpn_size = alpn[alpn_position++];
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if (alpn_size + alpn_position >= extension_length)
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break;
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String alpn_str { (const char*)alpn + alpn_position, alpn_length };
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if (alpn_size && m_context.alpn.contains_slow(alpn_str)) {
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m_context.negotiated_alpn = alpn_str;
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dbgln("negotiated alpn: {}", alpn_str);
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break;
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}
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alpn_position += alpn_length;
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if (!m_context.is_server) // server hello must contain one ALPN
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break;
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}
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}
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} else if (extension_type == HandshakeExtension::SignatureAlgorithms) {
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dbgln("supported signatures: ");
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print_buffer(buffer.slice(res, extension_length));
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// FIXME: what are we supposed to do here?
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} else {
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dbgln("Encountered unknown extension {} with length {}", (u16)extension_type, extension_length);
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}
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res += extension_length;
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} else if (extension_type == HandshakeExtension::SignatureAlgorithms) {
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dbgln("supported signatures: ");
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print_buffer(buffer.slice(res, extension_length));
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res += extension_length;
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// FIXME: what are we supposed to do here?
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} else {
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// Zero-length extensions.
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dbgln("Encountered unknown extension {} with length {}", (u16)extension_type, extension_length);
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res += extension_length;
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}
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}
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@ -372,9 +379,8 @@ ssize_t TLSv12::handle_payload(ReadonlyBytes vbuffer)
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if (m_context.is_server) {
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dbgln("unsupported: server mode");
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VERIFY_NOT_REACHED();
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} else {
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payload_res = handle_hello(buffer.slice(1, payload_size), write_packets);
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}
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payload_res = handle_hello(buffer.slice(1, payload_size), write_packets);
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break;
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case HelloVerifyRequest:
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dbgln("unsupported: DTLS");
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@ -585,6 +591,7 @@ ssize_t TLSv12::handle_payload(ReadonlyBytes vbuffer)
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}
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case Error::NeedMoreData:
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// Ignore this, as it's not an "error"
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dbgln_if(TLS_DEBUG, "More data needed");
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break;
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default:
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dbgln("Unknown TLS::Error with value {}", payload_res);
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