Function init [src]

Initiates a TLS handshake and establishes a TLSv1.2 or TLSv1.3 session with stream, which must conform to StreamInterface. host is only borrowed during this function call.
Prototype

pub fn init(stream: anytype, options: Options) InitError(@TypeOf(stream))!Client
Parameters

options: Options
Source

  pub fn init(stream: anytype, options: Options) InitError(@TypeOf(stream))!Client {
    const host = switch (options.host) {
        .no_verification => "",
        .explicit => |host| host,
    };
    const host_len: u16 = @intCast(host.len);

    var random_buffer: [176]u8 = undefined;
    crypto.random.bytes(&random_buffer);
    const client_hello_rand = random_buffer[0..32].*;
    var key_seq: u64 = 0;
    var server_hello_rand: [32]u8 = undefined;
    const legacy_session_id = random_buffer[32..64].*;

    var key_share = KeyShare.init(random_buffer[64..176].*) catch |err| switch (err) {
        // Only possible to happen if the seed is all zeroes.
        error.IdentityElement => return error.InsufficientEntropy,
    };

    const extensions_payload = tls.extension(.supported_versions, array(u8, tls.ProtocolVersion, .{
        .tls_1_3,
        .tls_1_2,
    })) ++ tls.extension(.signature_algorithms, array(u16, tls.SignatureScheme, .{
        .ecdsa_secp256r1_sha256,
        .ecdsa_secp384r1_sha384,
        .rsa_pkcs1_sha256,
        .rsa_pkcs1_sha384,
        .rsa_pkcs1_sha512,
        .rsa_pss_rsae_sha256,
        .rsa_pss_rsae_sha384,
        .rsa_pss_rsae_sha512,
        .rsa_pss_pss_sha256,
        .rsa_pss_pss_sha384,
        .rsa_pss_pss_sha512,
        .rsa_pkcs1_sha1,
        .ed25519,
    })) ++ tls.extension(.supported_groups, array(u16, tls.NamedGroup, .{
        .x25519_ml_kem768,
        .secp256r1,
        .secp384r1,
        .x25519,
    })) ++ tls.extension(.psk_key_exchange_modes, array(u8, tls.PskKeyExchangeMode, .{
        .psk_dhe_ke,
    })) ++ tls.extension(.key_share, array(
        u16,
        u8,
        int(u16, @intFromEnum(tls.NamedGroup.x25519_ml_kem768)) ++
            array(u16, u8, key_share.ml_kem768_kp.public_key.toBytes() ++ key_share.x25519_kp.public_key) ++
            int(u16, @intFromEnum(tls.NamedGroup.secp256r1)) ++
            array(u16, u8, key_share.secp256r1_kp.public_key.toUncompressedSec1()) ++
            int(u16, @intFromEnum(tls.NamedGroup.secp384r1)) ++
            array(u16, u8, key_share.secp384r1_kp.public_key.toUncompressedSec1()) ++
            int(u16, @intFromEnum(tls.NamedGroup.x25519)) ++
            array(u16, u8, key_share.x25519_kp.public_key),
    ));
    const server_name_extension = int(u16, @intFromEnum(tls.ExtensionType.server_name)) ++
        int(u16, 2 + 1 + 2 + host_len) ++ // byte length of this extension payload
        int(u16, 1 + 2 + host_len) ++ // server_name_list byte count
        .{0x00} ++ // name_type
        int(u16, host_len);
    const server_name_extension_len = switch (options.host) {
        .no_verification => 0,
        .explicit => server_name_extension.len + host_len,
    };

    const extensions_header =
        int(u16, @intCast(extensions_payload.len + server_name_extension_len)) ++
        extensions_payload ++
        server_name_extension;

    const client_hello =
        int(u16, @intFromEnum(tls.ProtocolVersion.tls_1_2)) ++
        client_hello_rand ++
        [1]u8{32} ++ legacy_session_id ++
        cipher_suites ++
        array(u8, tls.CompressionMethod, .{.null}) ++
        extensions_header;

    const out_handshake = .{@intFromEnum(tls.HandshakeType.client_hello)} ++
        int(u24, @intCast(client_hello.len - server_name_extension.len + server_name_extension_len)) ++
        client_hello;

    const cleartext_header_buf = .{@intFromEnum(tls.ContentType.handshake)} ++
        int(u16, @intFromEnum(tls.ProtocolVersion.tls_1_0)) ++
        int(u16, @intCast(out_handshake.len - server_name_extension.len + server_name_extension_len)) ++
        out_handshake;
    const cleartext_header = switch (options.host) {
        .no_verification => cleartext_header_buf[0 .. cleartext_header_buf.len - server_name_extension.len],
        .explicit => &cleartext_header_buf,
    };

    {
        var iovecs = [_]std.posix.iovec_const{
            .{ .base = cleartext_header.ptr, .len = cleartext_header.len },
            .{ .base = host.ptr, .len = host.len },
        };
        try stream.writevAll(iovecs[0..if (host.len == 0) 1 else 2]);
    }

    var tls_version: tls.ProtocolVersion = undefined;
    // These are used for two purposes:
    // * Detect whether a certificate is the first one presented, in which case
    //   we need to verify the host name.
    var cert_index: usize = 0;
    // * Flip back and forth between the two cleartext buffers in order to keep
    //   the previous certificate in memory so that it can be verified by the
    //   next one.
    var cert_buf_index: usize = 0;
    var write_seq: u64 = 0;
    var read_seq: u64 = 0;
    var prev_cert: Certificate.Parsed = undefined;
    const CipherState = enum {
        /// No cipher is in use
        cleartext,
        /// Handshake cipher is in use
        handshake,
        /// Application cipher is in use
        application,
    };
    var pending_cipher_state: CipherState = .cleartext;
    var cipher_state = pending_cipher_state;
    const HandshakeState = enum {
        /// In this state we expect only a server hello message.
        hello,
        /// In this state we expect only an encrypted_extensions message.
        encrypted_extensions,
        /// In this state we expect certificate handshake messages.
        certificate,
        /// In this state we expect certificate or certificate_verify messages.
        /// certificate messages are ignored since the trust chain is already
        /// established.
        trust_chain_established,
        /// In this state, we expect only the server_hello_done handshake message.
        server_hello_done,
        /// In this state, we expect only the finished handshake message.
        finished,
    };
    var handshake_state: HandshakeState = .hello;
    var handshake_cipher: tls.HandshakeCipher = undefined;
    var main_cert_pub_key: CertificatePublicKey = undefined;
    const now_sec = std.time.timestamp();

    var cleartext_fragment_start: usize = 0;
    var cleartext_fragment_end: usize = 0;
    var cleartext_bufs: [2][tls.max_ciphertext_inner_record_len]u8 = undefined;
    var handshake_buffer: [tls.max_ciphertext_record_len]u8 = undefined;
    var d: tls.Decoder = .{ .buf = &handshake_buffer };
    fragment: while (true) {
        try d.readAtLeastOurAmt(stream, tls.record_header_len);
        const record_header = d.buf[d.idx..][0..tls.record_header_len];
        const record_ct = d.decode(tls.ContentType);
        d.skip(2); // legacy_version
        const record_len = d.decode(u16);
        try d.readAtLeast(stream, record_len);
        var record_decoder = try d.sub(record_len);
        var ctd, const ct = content: switch (cipher_state) {
            .cleartext => .{ record_decoder, record_ct },
            .handshake => {
                std.debug.assert(tls_version == .tls_1_3);
                if (record_ct != .application_data) return error.TlsUnexpectedMessage;
                try record_decoder.ensure(record_len);
                const cleartext_buf = &cleartext_bufs[cert_buf_index % 2];
                switch (handshake_cipher) {
                    inline else => |*p| {
                        const pv = &p.version.tls_1_3;
                        const P = @TypeOf(p.*).A;
                        if (record_len < P.AEAD.tag_length) return error.TlsRecordOverflow;
                        const ciphertext = record_decoder.slice(record_len - P.AEAD.tag_length);
                        const cleartext_fragment_buf = cleartext_buf[cleartext_fragment_end..];
                        if (ciphertext.len > cleartext_fragment_buf.len) return error.TlsRecordOverflow;
                        const cleartext = cleartext_fragment_buf[0..ciphertext.len];
                        const auth_tag = record_decoder.array(P.AEAD.tag_length).*;
                        const nonce = nonce: {
                            const V = @Vector(P.AEAD.nonce_length, u8);
                            const pad = [1]u8{0} ** (P.AEAD.nonce_length - 8);
                            const operand: V = pad ++ @as([8]u8, @bitCast(big(read_seq)));
                            break :nonce @as(V, pv.server_handshake_iv) ^ operand;
                        };
                        P.AEAD.decrypt(cleartext, ciphertext, auth_tag, record_header, nonce, pv.server_handshake_key) catch
                            return error.TlsBadRecordMac;
                        cleartext_fragment_end += std.mem.trimRight(u8, cleartext, "\x00").len;
                    },
                }
                read_seq += 1;
                cleartext_fragment_end -= 1;
                const ct: tls.ContentType = @enumFromInt(cleartext_buf[cleartext_fragment_end]);
                if (ct != .handshake) return error.TlsUnexpectedMessage;
                break :content .{ tls.Decoder.fromTheirSlice(@constCast(cleartext_buf[cleartext_fragment_start..cleartext_fragment_end])), ct };
            },
            .application => {
                std.debug.assert(tls_version == .tls_1_2);
                if (record_ct != .handshake) return error.TlsUnexpectedMessage;
                try record_decoder.ensure(record_len);
                const cleartext_buf = &cleartext_bufs[cert_buf_index % 2];
                switch (handshake_cipher) {
                    inline else => |*p| {
                        const pv = &p.version.tls_1_2;
                        const P = @TypeOf(p.*).A;
                        if (record_len < P.record_iv_length + P.mac_length) return error.TlsRecordOverflow;
                        const message_len: u16 = record_len - P.record_iv_length - P.mac_length;
                        const cleartext_fragment_buf = cleartext_buf[cleartext_fragment_end..];
                        if (message_len > cleartext_fragment_buf.len) return error.TlsRecordOverflow;
                        const cleartext = cleartext_fragment_buf[0..message_len];
                        const ad = std.mem.toBytes(big(read_seq)) ++
                            record_header[0 .. 1 + 2] ++
                            std.mem.toBytes(big(message_len));
                        const record_iv = record_decoder.array(P.record_iv_length).*;
                        const masked_read_seq = read_seq &
                            comptime std.math.shl(u64, std.math.maxInt(u64), 8 * P.record_iv_length);
                        const nonce: [P.AEAD.nonce_length]u8 = nonce: {
                            const V = @Vector(P.AEAD.nonce_length, u8);
                            const pad = [1]u8{0} ** (P.AEAD.nonce_length - 8);
                            const operand: V = pad ++ @as([8]u8, @bitCast(big(masked_read_seq)));
                            break :nonce @as(V, pv.app_cipher.server_write_IV ++ record_iv) ^ operand;
                        };
                        const ciphertext = record_decoder.slice(message_len);
                        const auth_tag = record_decoder.array(P.mac_length);
                        P.AEAD.decrypt(cleartext, ciphertext, auth_tag.*, ad, nonce, pv.app_cipher.server_write_key) catch return error.TlsBadRecordMac;
                        cleartext_fragment_end += message_len;
                    },
                }
                read_seq += 1;
                break :content .{ tls.Decoder.fromTheirSlice(cleartext_buf[cleartext_fragment_start..cleartext_fragment_end]), record_ct };
            },
        };
        switch (ct) {
            .alert => {
                ctd.ensure(2) catch continue :fragment;
                const level = ctd.decode(tls.AlertLevel);
                const desc = ctd.decode(tls.AlertDescription);
                _ = level;

                // if this isn't a error alert, then it's a closure alert, which makes no sense in a handshake
                try desc.toError();
                // TODO: handle server-side closures
                return error.TlsUnexpectedMessage;
            },
            .change_cipher_spec => {
                ctd.ensure(1) catch continue :fragment;
                if (ctd.decode(tls.ChangeCipherSpecType) != .change_cipher_spec) return error.TlsIllegalParameter;
                cipher_state = pending_cipher_state;
            },
            .handshake => while (true) {
                ctd.ensure(4) catch continue :fragment;
                const handshake_type = ctd.decode(tls.HandshakeType);
                const handshake_len = ctd.decode(u24);
                var hsd = ctd.sub(handshake_len) catch continue :fragment;
                const wrapped_handshake = ctd.buf[ctd.idx - handshake_len - 4 .. ctd.idx];
                switch (handshake_type) {
                    .server_hello => {
                        if (cipher_state != .cleartext) return error.TlsUnexpectedMessage;
                        if (handshake_state != .hello) return error.TlsUnexpectedMessage;
                        try hsd.ensure(2 + 32 + 1);
                        const legacy_version = hsd.decode(u16);
                        @memcpy(&server_hello_rand, hsd.array(32));
                        if (mem.eql(u8, &server_hello_rand, &tls.hello_retry_request_sequence)) {
                            // This is a HelloRetryRequest message. This client implementation
                            // does not expect to get one.
                            return error.TlsUnexpectedMessage;
                        }
                        const legacy_session_id_echo_len = hsd.decode(u8);
                        try hsd.ensure(legacy_session_id_echo_len + 2 + 1);
                        const legacy_session_id_echo = hsd.slice(legacy_session_id_echo_len);
                        const cipher_suite_tag = hsd.decode(tls.CipherSuite);
                        hsd.skip(1); // legacy_compression_method
                        var supported_version: ?u16 = null;
                        if (!hsd.eof()) {
                            try hsd.ensure(2);
                            const extensions_size = hsd.decode(u16);
                            var all_extd = try hsd.sub(extensions_size);
                            while (!all_extd.eof()) {
                                try all_extd.ensure(2 + 2);
                                const et = all_extd.decode(tls.ExtensionType);
                                const ext_size = all_extd.decode(u16);
                                var extd = try all_extd.sub(ext_size);
                                switch (et) {
                                    .supported_versions => {
                                        if (supported_version) |_| return error.TlsIllegalParameter;
                                        try extd.ensure(2);
                                        supported_version = extd.decode(u16);
                                    },
                                    .key_share => {
                                        if (key_share.getSharedSecret()) |_| return error.TlsIllegalParameter;
                                        try extd.ensure(4);
                                        const named_group = extd.decode(tls.NamedGroup);
                                        const key_size = extd.decode(u16);
                                        try extd.ensure(key_size);
                                        try key_share.exchange(named_group, extd.slice(key_size));
                                    },
                                    else => {},
                                }
                            }
                        }

                        tls_version = @enumFromInt(supported_version orelse legacy_version);
                        switch (tls_version) {
                            .tls_1_3 => if (!mem.eql(u8, legacy_session_id_echo, &legacy_session_id)) return error.TlsIllegalParameter,
                            .tls_1_2 => if (mem.eql(u8, server_hello_rand[24..31], "DOWNGRD") and
                                server_hello_rand[31] >> 1 == 0x00) return error.TlsIllegalParameter,
                            else => return error.TlsIllegalParameter,
                        }

                        switch (cipher_suite_tag) {
                            inline .AES_128_GCM_SHA256,
                            .AES_256_GCM_SHA384,
                            .CHACHA20_POLY1305_SHA256,
                            .AEGIS_256_SHA512,
                            .AEGIS_128L_SHA256,

                            .ECDHE_RSA_WITH_AES_128_GCM_SHA256,
                            .ECDHE_RSA_WITH_AES_256_GCM_SHA384,
                            .ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
                            => |tag| {
                                handshake_cipher = @unionInit(tls.HandshakeCipher, @tagName(tag.with()), .{
                                    .transcript_hash = .init(.{}),
                                    .version = undefined,
                                });
                                const p = &@field(handshake_cipher, @tagName(tag.with()));
                                p.transcript_hash.update(cleartext_header[tls.record_header_len..]); // Client Hello part 1
                                p.transcript_hash.update(host); // Client Hello part 2
                                p.transcript_hash.update(wrapped_handshake);
                            },

                            else => return error.TlsIllegalParameter,
                        }
                        switch (tls_version) {
                            .tls_1_3 => {
                                switch (cipher_suite_tag) {
                                    inline .AES_128_GCM_SHA256,
                                    .AES_256_GCM_SHA384,
                                    .CHACHA20_POLY1305_SHA256,
                                    .AEGIS_256_SHA512,
                                    .AEGIS_128L_SHA256,
                                    => |tag| {
                                        const sk = key_share.getSharedSecret() orelse return error.TlsIllegalParameter;
                                        const p = &@field(handshake_cipher, @tagName(tag.with()));
                                        const P = @TypeOf(p.*).A;
                                        const hello_hash = p.transcript_hash.peek();
                                        const zeroes = [1]u8{0} ** P.Hash.digest_length;
                                        const early_secret = P.Hkdf.extract(&[1]u8{0}, &zeroes);
                                        const empty_hash = tls.emptyHash(P.Hash);
                                        p.version = .{ .tls_1_3 = undefined };
                                        const pv = &p.version.tls_1_3;
                                        const hs_derived_secret = hkdfExpandLabel(P.Hkdf, early_secret, "derived", &empty_hash, P.Hash.digest_length);
                                        pv.handshake_secret = P.Hkdf.extract(&hs_derived_secret, sk);
                                        const ap_derived_secret = hkdfExpandLabel(P.Hkdf, pv.handshake_secret, "derived", &empty_hash, P.Hash.digest_length);
                                        pv.master_secret = P.Hkdf.extract(&ap_derived_secret, &zeroes);
                                        const client_secret = hkdfExpandLabel(P.Hkdf, pv.handshake_secret, "c hs traffic", &hello_hash, P.Hash.digest_length);
                                        const server_secret = hkdfExpandLabel(P.Hkdf, pv.handshake_secret, "s hs traffic", &hello_hash, P.Hash.digest_length);
                                        if (options.ssl_key_log_file) |key_log_file| logSecrets(key_log_file, .{
                                            .client_random = &client_hello_rand,
                                        }, .{
                                            .SERVER_HANDSHAKE_TRAFFIC_SECRET = &server_secret,
                                            .CLIENT_HANDSHAKE_TRAFFIC_SECRET = &client_secret,
                                        });
                                        pv.client_finished_key = hkdfExpandLabel(P.Hkdf, client_secret, "finished", "", P.Hmac.key_length);
                                        pv.server_finished_key = hkdfExpandLabel(P.Hkdf, server_secret, "finished", "", P.Hmac.key_length);
                                        pv.client_handshake_key = hkdfExpandLabel(P.Hkdf, client_secret, "key", "", P.AEAD.key_length);
                                        pv.server_handshake_key = hkdfExpandLabel(P.Hkdf, server_secret, "key", "", P.AEAD.key_length);
                                        pv.client_handshake_iv = hkdfExpandLabel(P.Hkdf, client_secret, "iv", "", P.AEAD.nonce_length);
                                        pv.server_handshake_iv = hkdfExpandLabel(P.Hkdf, server_secret, "iv", "", P.AEAD.nonce_length);
                                    },
                                    else => return error.TlsIllegalParameter,
                                }
                                pending_cipher_state = .handshake;
                                handshake_state = .encrypted_extensions;
                            },
                            .tls_1_2 => switch (cipher_suite_tag) {
                                .ECDHE_RSA_WITH_AES_128_GCM_SHA256,
                                .ECDHE_RSA_WITH_AES_256_GCM_SHA384,
                                .ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256,
                                => handshake_state = .certificate,
                                else => return error.TlsIllegalParameter,
                            },
                            else => return error.TlsIllegalParameter,
                        }
                    },
                    .encrypted_extensions => {
                        if (tls_version != .tls_1_3) return error.TlsUnexpectedMessage;
                        if (cipher_state != .handshake) return error.TlsUnexpectedMessage;
                        if (handshake_state != .encrypted_extensions) return error.TlsUnexpectedMessage;
                        switch (handshake_cipher) {
                            inline else => |*p| p.transcript_hash.update(wrapped_handshake),
                        }
                        try hsd.ensure(2);
                        const total_ext_size = hsd.decode(u16);
                        var all_extd = try hsd.sub(total_ext_size);
                        while (!all_extd.eof()) {
                            try all_extd.ensure(4);
                            const et = all_extd.decode(tls.ExtensionType);
                            const ext_size = all_extd.decode(u16);
                            const extd = try all_extd.sub(ext_size);
                            _ = extd;
                            switch (et) {
                                .server_name => {},
                                else => {},
                            }
                        }
                        handshake_state = .certificate;
                    },
                    .certificate => cert: {
                        if (cipher_state == .application) return error.TlsUnexpectedMessage;
                        switch (handshake_state) {
                            .certificate => {},
                            .trust_chain_established => break :cert,
                            else => return error.TlsUnexpectedMessage,
                        }
                        switch (handshake_cipher) {
                            inline else => |*p| p.transcript_hash.update(wrapped_handshake),
                        }

                        switch (tls_version) {
                            .tls_1_3 => {
                                try hsd.ensure(1 + 3);
                                const cert_req_ctx_len = hsd.decode(u8);
                                if (cert_req_ctx_len != 0) return error.TlsIllegalParameter;
                            },
                            .tls_1_2 => try hsd.ensure(3),
                            else => unreachable,
                        }
                        const certs_size = hsd.decode(u24);
                        var certs_decoder = try hsd.sub(certs_size);
                        while (!certs_decoder.eof()) {
                            try certs_decoder.ensure(3);
                            const cert_size = certs_decoder.decode(u24);
                            const certd = try certs_decoder.sub(cert_size);

                            if (tls_version == .tls_1_3) {
                                try certs_decoder.ensure(2);
                                const total_ext_size = certs_decoder.decode(u16);
                                const all_extd = try certs_decoder.sub(total_ext_size);
                                _ = all_extd;
                            }

                            const subject_cert: Certificate = .{
                                .buffer = certd.buf,
                                .index = @intCast(certd.idx),
                            };
                            const subject = try subject_cert.parse();
                            if (cert_index == 0) {
                                // Verify the host on the first certificate.
                                switch (options.host) {
                                    .no_verification => {},
                                    .explicit => try subject.verifyHostName(host),
                                }

                                // Keep track of the public key for the
                                // certificate_verify message later.
                                try main_cert_pub_key.init(subject.pub_key_algo, subject.pubKey());
                            } else {
                                try prev_cert.verify(subject, now_sec);
                            }

                            switch (options.ca) {
                                .no_verification => {
                                    handshake_state = .trust_chain_established;
                                    break :cert;
                                },
                                .self_signed => {
                                    try subject.verify(subject, now_sec);
                                    handshake_state = .trust_chain_established;
                                    break :cert;
                                },
                                .bundle => |ca_bundle| if (ca_bundle.verify(subject, now_sec)) |_| {
                                    handshake_state = .trust_chain_established;
                                    break :cert;
                                } else |err| switch (err) {
                                    error.CertificateIssuerNotFound => {},
                                    else => |e| return e,
                                },
                            }

                            prev_cert = subject;
                            cert_index += 1;
                        }
                        cert_buf_index += 1;
                    },
                    .server_key_exchange => {
                        if (tls_version != .tls_1_2) return error.TlsUnexpectedMessage;
                        if (cipher_state != .cleartext) return error.TlsUnexpectedMessage;
                        switch (handshake_state) {
                            .trust_chain_established => {},
                            .certificate => return error.TlsCertificateNotVerified,
                            else => return error.TlsUnexpectedMessage,
                        }

                        switch (handshake_cipher) {
                            inline else => |*p| p.transcript_hash.update(wrapped_handshake),
                        }
                        try hsd.ensure(1 + 2 + 1);
                        const curve_type = hsd.decode(u8);
                        if (curve_type != 0x03) return error.TlsIllegalParameter; // named_curve
                        const named_group = hsd.decode(tls.NamedGroup);
                        const key_size = hsd.decode(u8);
                        try hsd.ensure(key_size);
                        const server_pub_key = hsd.slice(key_size);
                        try main_cert_pub_key.verifySignature(&hsd, &.{ &client_hello_rand, &server_hello_rand, hsd.buf[0..hsd.idx] });
                        try key_share.exchange(named_group, server_pub_key);
                        handshake_state = .server_hello_done;
                    },
                    .server_hello_done => {
                        if (tls_version != .tls_1_2) return error.TlsUnexpectedMessage;
                        if (cipher_state != .cleartext) return error.TlsUnexpectedMessage;
                        if (handshake_state != .server_hello_done) return error.TlsUnexpectedMessage;

                        const client_key_exchange_msg = .{@intFromEnum(tls.ContentType.handshake)} ++
                            int(u16, @intFromEnum(tls.ProtocolVersion.tls_1_2)) ++
                            array(u16, u8, .{@intFromEnum(tls.HandshakeType.client_key_exchange)} ++
                                array(u24, u8, array(u8, u8, key_share.secp256r1_kp.public_key.toUncompressedSec1())));
                        const client_change_cipher_spec_msg = .{@intFromEnum(tls.ContentType.change_cipher_spec)} ++
                            int(u16, @intFromEnum(tls.ProtocolVersion.tls_1_2)) ++
                            array(u16, tls.ChangeCipherSpecType, .{.change_cipher_spec});
                        const pre_master_secret = key_share.getSharedSecret().?;
                        switch (handshake_cipher) {
                            inline else => |*p| {
                                const P = @TypeOf(p.*).A;
                                p.transcript_hash.update(wrapped_handshake);
                                p.transcript_hash.update(client_key_exchange_msg[tls.record_header_len..]);
                                const master_secret = hmacExpandLabel(P.Hmac, pre_master_secret, &.{
                                    "master secret",
                                    &client_hello_rand,
                                    &server_hello_rand,
                                }, 48);
                                if (options.ssl_key_log_file) |key_log_file| logSecrets(key_log_file, .{
                                    .client_random = &client_hello_rand,
                                }, .{
                                    .CLIENT_RANDOM = &master_secret,
                                });
                                const key_block = hmacExpandLabel(
                                    P.Hmac,
                                    &master_secret,
                                    &.{ "key expansion", &server_hello_rand, &client_hello_rand },
                                    @sizeOf(P.Tls_1_2),
                                );
                                const client_verify_cleartext = .{@intFromEnum(tls.HandshakeType.finished)} ++
                                    array(u24, u8, hmacExpandLabel(
                                        P.Hmac,
                                        &master_secret,
                                        &.{ "client finished", &p.transcript_hash.peek() },
                                        P.verify_data_length,
                                    ));
                                p.transcript_hash.update(&client_verify_cleartext);
                                p.version = .{ .tls_1_2 = .{
                                    .expected_server_verify_data = hmacExpandLabel(
                                        P.Hmac,
                                        &master_secret,
                                        &.{ "server finished", &p.transcript_hash.finalResult() },
                                        P.verify_data_length,
                                    ),
                                    .app_cipher = std.mem.bytesToValue(P.Tls_1_2, &key_block),
                                } };
                                const pv = &p.version.tls_1_2;
                                const nonce: [P.AEAD.nonce_length]u8 = nonce: {
                                    const V = @Vector(P.AEAD.nonce_length, u8);
                                    const pad = [1]u8{0} ** (P.AEAD.nonce_length - 8);
                                    const operand: V = pad ++ @as([8]u8, @bitCast(big(write_seq)));
                                    break :nonce @as(V, pv.app_cipher.client_write_IV ++ pv.app_cipher.client_salt) ^ operand;
                                };
                                var client_verify_msg = .{@intFromEnum(tls.ContentType.handshake)} ++
                                    int(u16, @intFromEnum(tls.ProtocolVersion.tls_1_2)) ++
                                    array(u16, u8, nonce[P.fixed_iv_length..].* ++
                                        @as([client_verify_cleartext.len + P.mac_length]u8, undefined));
                                P.AEAD.encrypt(
                                    client_verify_msg[client_verify_msg.len - P.mac_length -
                                        client_verify_cleartext.len ..][0..client_verify_cleartext.len],
                                    client_verify_msg[client_verify_msg.len - P.mac_length ..][0..P.mac_length],
                                    &client_verify_cleartext,
                                    std.mem.toBytes(big(write_seq)) ++ client_verify_msg[0 .. 1 + 2] ++ int(u16, client_verify_cleartext.len),
                                    nonce,
                                    pv.app_cipher.client_write_key,
                                );
                                const all_msgs = client_key_exchange_msg ++ client_change_cipher_spec_msg ++ client_verify_msg;
                                var all_msgs_vec = [_]std.posix.iovec_const{
                                    .{ .base = &all_msgs, .len = all_msgs.len },
                                };
                                try stream.writevAll(&all_msgs_vec);
                            },
                        }
                        write_seq += 1;
                        pending_cipher_state = .application;
                        handshake_state = .finished;
                    },
                    .certificate_verify => {
                        if (tls_version != .tls_1_3) return error.TlsUnexpectedMessage;
                        if (cipher_state != .handshake) return error.TlsUnexpectedMessage;
                        switch (handshake_state) {
                            .trust_chain_established => {},
                            .certificate => return error.TlsCertificateNotVerified,
                            else => return error.TlsUnexpectedMessage,
                        }
                        switch (handshake_cipher) {
                            inline else => |*p| {
                                try main_cert_pub_key.verifySignature(&hsd, &.{
                                    " " ** 64 ++ "TLS 1.3, server CertificateVerify\x00",
                                    &p.transcript_hash.peek(),
                                });
                                p.transcript_hash.update(wrapped_handshake);
                            },
                        }
                        handshake_state = .finished;
                    },
                    .finished => {
                        if (cipher_state == .cleartext) return error.TlsUnexpectedMessage;
                        if (handshake_state != .finished) return error.TlsUnexpectedMessage;
                        // This message is to trick buggy proxies into behaving correctly.
                        const client_change_cipher_spec_msg = .{@intFromEnum(tls.ContentType.change_cipher_spec)} ++
                            int(u16, @intFromEnum(tls.ProtocolVersion.tls_1_2)) ++
                            array(u16, tls.ChangeCipherSpecType, .{.change_cipher_spec});
                        const app_cipher = app_cipher: switch (handshake_cipher) {
                            inline else => |*p, tag| switch (tls_version) {
                                .tls_1_3 => {
                                    const pv = &p.version.tls_1_3;
                                    const P = @TypeOf(p.*).A;
                                    try hsd.ensure(P.Hmac.mac_length);
                                    const finished_digest = p.transcript_hash.peek();
                                    p.transcript_hash.update(wrapped_handshake);
                                    const expected_server_verify_data = tls.hmac(P.Hmac, &finished_digest, pv.server_finished_key);
                                    if (!std.crypto.timing_safe.eql([P.Hmac.mac_length]u8, expected_server_verify_data, hsd.array(P.Hmac.mac_length).*)) return error.TlsDecryptError;
                                    const handshake_hash = p.transcript_hash.finalResult();
                                    const verify_data = tls.hmac(P.Hmac, &handshake_hash, pv.client_finished_key);
                                    const out_cleartext = .{@intFromEnum(tls.HandshakeType.finished)} ++
                                        array(u24, u8, verify_data) ++
                                        .{@intFromEnum(tls.ContentType.handshake)};

                                    const wrapped_len = out_cleartext.len + P.AEAD.tag_length;

                                    var finished_msg = .{@intFromEnum(tls.ContentType.application_data)} ++
                                        int(u16, @intFromEnum(tls.ProtocolVersion.tls_1_2)) ++
                                        array(u16, u8, @as([wrapped_len]u8, undefined));

                                    const ad = finished_msg[0..tls.record_header_len];
                                    const ciphertext = finished_msg[tls.record_header_len..][0..out_cleartext.len];
                                    const auth_tag = finished_msg[finished_msg.len - P.AEAD.tag_length ..];
                                    const nonce = pv.client_handshake_iv;
                                    P.AEAD.encrypt(ciphertext, auth_tag, &out_cleartext, ad, nonce, pv.client_handshake_key);

                                    const all_msgs = client_change_cipher_spec_msg ++ finished_msg;
                                    var all_msgs_vec = [_]std.posix.iovec_const{
                                        .{ .base = &all_msgs, .len = all_msgs.len },
                                    };
                                    try stream.writevAll(&all_msgs_vec);

                                    const client_secret = hkdfExpandLabel(P.Hkdf, pv.master_secret, "c ap traffic", &handshake_hash, P.Hash.digest_length);
                                    const server_secret = hkdfExpandLabel(P.Hkdf, pv.master_secret, "s ap traffic", &handshake_hash, P.Hash.digest_length);
                                    if (options.ssl_key_log_file) |key_log_file| logSecrets(key_log_file, .{
                                        .counter = key_seq,
                                        .client_random = &client_hello_rand,
                                    }, .{
                                        .SERVER_TRAFFIC_SECRET = &server_secret,
                                        .CLIENT_TRAFFIC_SECRET = &client_secret,
                                    });
                                    key_seq += 1;
                                    break :app_cipher @unionInit(tls.ApplicationCipher, @tagName(tag), .{ .tls_1_3 = .{
                                        .client_secret = client_secret,
                                        .server_secret = server_secret,
                                        .client_key = hkdfExpandLabel(P.Hkdf, client_secret, "key", "", P.AEAD.key_length),
                                        .server_key = hkdfExpandLabel(P.Hkdf, server_secret, "key", "", P.AEAD.key_length),
                                        .client_iv = hkdfExpandLabel(P.Hkdf, client_secret, "iv", "", P.AEAD.nonce_length),
                                        .server_iv = hkdfExpandLabel(P.Hkdf, server_secret, "iv", "", P.AEAD.nonce_length),
                                    } });
                                },
                                .tls_1_2 => {
                                    const pv = &p.version.tls_1_2;
                                    const P = @TypeOf(p.*).A;
                                    try hsd.ensure(P.verify_data_length);
                                    if (!std.crypto.timing_safe.eql([P.verify_data_length]u8, pv.expected_server_verify_data, hsd.array(P.verify_data_length).*)) return error.TlsDecryptError;
                                    break :app_cipher @unionInit(tls.ApplicationCipher, @tagName(tag), .{ .tls_1_2 = pv.app_cipher });
                                },
                                else => unreachable,
                            },
                        };
                        const leftover = d.rest();
                        var client: Client = .{
                            .tls_version = tls_version,
                            .read_seq = switch (tls_version) {
                                .tls_1_3 => 0,
                                .tls_1_2 => read_seq,
                                else => unreachable,
                            },
                            .write_seq = switch (tls_version) {
                                .tls_1_3 => 0,
                                .tls_1_2 => write_seq,
                                else => unreachable,
                            },
                            .partial_cleartext_idx = 0,
                            .partial_ciphertext_idx = 0,
                            .partial_ciphertext_end = @intCast(leftover.len),
                            .received_close_notify = false,
                            .allow_truncation_attacks = false,
                            .application_cipher = app_cipher,
                            .partially_read_buffer = undefined,
                            .ssl_key_log = if (options.ssl_key_log_file) |key_log_file| .{
                                .client_key_seq = key_seq,
                                .server_key_seq = key_seq,
                                .client_random = client_hello_rand,
                                .file = key_log_file,
                            } else null,
                        };
                        @memcpy(client.partially_read_buffer[0..leftover.len], leftover);
                        return client;
                    },
                    else => return error.TlsUnexpectedMessage,
                }
                if (ctd.eof()) break;
                cleartext_fragment_start = ctd.idx;
            },
            else => return error.TlsUnexpectedMessage,
        }
        cleartext_fragment_start = 0;
        cleartext_fragment_end = 0;
    }
}  