Success path for fake tls is implemented

tlstypes/certificate_server.go

@@ -0,0 +1,80 @@
+package tlstypes
+
+import (
+	"container/ring"
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"net"
+	"strconv"
+	"time"
+
+	"go.uber.org/zap"
+
+	"github.com/9seconds/mtg/config"
+)
+
+const (
+	connectionServerKeepCertificates = 5
+	connectionServerUpdateEvery      = 10 * time.Minute
+)
+
+type connectionServer struct {
+	nextWriteItem *ring.Ring
+	nextReadItem  *ring.Ring
+
+	ctx        context.Context
+	channelGet chan chan<- *x509.Certificate
+}
+
+func (c *connectionServer) fetch() (*x509.Certificate, error) {
+	addr := net.JoinHostPort(config.C.CloakHost, strconv.Itoa(config.C.CloakPort))
+	conn, err := tls.Dial("tcp", addr, &tls.Config{InsecureSkipVerify: true}) // nolint: gosec
+
+	if err != nil {
+		return nil, fmt.Errorf("cannot connect to the masked host: %w", err)
+	}
+
+	defer conn.Close()
+
+	if err = conn.Handshake(); err != nil {
+		return nil, fmt.Errorf("cannot perform tls handshake: %w", err)
+	}
+
+	certificates := conn.ConnectionState().PeerCertificates
+	if len(certificates) == 0 {
+		return nil, errors.New("no certificates is found")
+	}
+
+	return certificates[0], nil
+}
+
+func (c *connectionServer) run() {
+	logger := zap.S().Named("tls-connection-server")
+
+	ticker := time.NewTicker(connectionServerUpdateEvery)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-c.ctx.Done():
+			return
+		case resp := <-c.channelGet:
+			resp <- c.nextReadItem.Value.(*x509.Certificate)
+			close(resp)
+
+			c.nextReadItem = c.nextReadItem.Next()
+		case <-ticker.C:
+			cert, err := c.fetch()
+			switch err {
+			case nil:
+				c.nextWriteItem.Value = cert
+				c.nextWriteItem = c.nextWriteItem.Next()
+			default:
+				logger.Warnw("cannot fetch certificates", "error", err)
+			}
+		}
+	}
+}

tlstypes/client_hello.go

@@ -0,0 +1,86 @@
+package tlstypes
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha256"
+	"fmt"
+
+	"github.com/9seconds/mtg/config"
+	"github.com/9seconds/mtg/utils"
+)
+
+type ClientHello struct {
+	Handshake
+}
+
+func (c ClientHello) Digest() []byte {
+	dirtyDigest := c.Random
+	c.Random = [32]byte{}
+
+	rec := Record{
+		Type:    RecordTypeHandshake,
+		Version: Version10,
+		Data:    &c,
+	}
+
+	mac := hmac.New(sha256.New, config.C.Secret)
+	mac.Write(rec.Bytes()) // nolint: errcheck
+	computedDigest := mac.Sum(nil)
+
+	for i := range computedDigest {
+		computedDigest[i] ^= dirtyDigest[i]
+	}
+
+	return computedDigest
+}
+
+func ParseClientHello(raw []byte) (*ClientHello, error) {
+	rv := &ClientHello{}
+
+	rv.Type = HandshakeType(raw[0])
+	if rv.Type != HandshakeTypeClient {
+		return nil, fmt.Errorf("incorrect handshake type %v", rv.Type)
+	}
+
+	raw = raw[1:]
+	sizeUint24 := utils.Uint24{}
+	copy(sizeUint24[:], utils.ReverseBytes(raw[:3]))
+	size := int(utils.FromUint24(sizeUint24))
+
+	raw = raw[3:]
+	if len(raw) != size {
+		return nil, fmt.Errorf("payload size mismatch (%d != %d)", len(raw), size)
+	}
+
+	versionRaw := raw[:2]
+
+	switch {
+	case bytes.Equal(versionRaw, Version13Bytes):
+		rv.Version = Version13
+	case bytes.Equal(versionRaw, Version12Bytes):
+		rv.Version = Version12
+	case bytes.Equal(versionRaw, Version11Bytes):
+		rv.Version = Version11
+	case bytes.Equal(versionRaw, Version10Bytes):
+		rv.Version = Version10
+	default:
+		return nil, fmt.Errorf("unknown protocol version %v", versionRaw)
+	}
+
+	raw = raw[2:]
+	copy(rv.Random[:], raw[:32])
+	raw = raw[32:]
+
+	sessionIDLength := int(raw[0])
+	raw = raw[1:]
+	rv.SessionID = make([]byte, sessionIDLength)
+	copy(rv.SessionID, raw)
+	raw = raw[sessionIDLength:]
+
+	tail := make([]byte, len(raw))
+	copy(tail, raw)
+	rv.Tail = RawBytes(tail)
+
+	return rv, nil
+}

tlstypes/consts.go

@@ -0,0 +1,79 @@
+package tlstypes
+
+type RecordType uint8
+
+const (
+	RecordTypeHandshake        RecordType = 0x16
+	RecordTypeApplicationData  RecordType = 0x17
+	RecordTypeChangeCipherSpec RecordType = 0x14
+)
+
+type HandshakeType uint8
+
+const (
+	HandshakeTypeClient HandshakeType = 0x01
+	HandshakeTypeServer HandshakeType = 0x02
+)
+
+type CipherSuiteType uint8
+
+const (
+	CipherSuiteType_TLS_AES_128_GCM_SHA256       CipherSuiteType = iota // nolint: stylecheck, golint
+	CipherSuiteType_TLS_AES_256_GCM_SHA384                              // nolint: stylecheck, golint
+	CipherSuiteType_TLS_CHACHA20_POLY1305_SHA256                        // nolint: stylecheck, golint
+)
+
+func (c CipherSuiteType) Bytes() []byte {
+	switch c {
+	case CipherSuiteType_TLS_AES_128_GCM_SHA256:
+		return CipherSuiteType_TLS_AES_128_GCM_SHA256_Bytes
+	case CipherSuiteType_TLS_AES_256_GCM_SHA384:
+		return CipherSuiteType_TLS_AES_256_GCM_SHA384_Bytes
+	}
+
+	return CipherSuiteType_TLS_CHACHA20_POLY1305_SHA256_Bytes
+}
+
+type Version uint8
+
+func (v Version) Bytes() []byte {
+	switch v {
+	case Version13:
+		return Version13Bytes
+	case Version12:
+		return Version12Bytes
+	case Version11:
+		return Version11Bytes
+	}
+
+	return Version10Bytes
+}
+
+const (
+	VersionUnknown Version = iota
+	Version10
+	Version11
+	Version12
+	Version13
+)
+
+var (
+	Version10Bytes = []byte{0x03, 0x01}
+	Version11Bytes = []byte{0x03, 0x02}
+	Version12Bytes = []byte{0x03, 0x03}
+	Version13Bytes = []byte{0x03, 0x04}
+
+	CipherSuiteType_TLS_AES_128_GCM_SHA256_Bytes       = []byte{0x13, 0x01} // nolint: stylecheck, golint
+	CipherSuiteType_TLS_AES_256_GCM_SHA384_Bytes       = []byte{0x13, 0x02} // nolint: stylecheck, golint
+	CipherSuiteType_TLS_CHACHA20_POLY1305_SHA256_Bytes = []byte{0x13, 0x03} // nolint; stylecheck, golint
+)
+
+type Byter interface {
+	Bytes() []byte
+}
+
+type RawBytes []byte
+
+func (r RawBytes) Bytes() []byte {
+	return []byte(r)
+}

tlstypes/handshake.go

@@ -0,0 +1,37 @@
+package tlstypes
+
+import (
+	"bytes"
+
+	"github.com/9seconds/mtg/utils"
+)
+
+type Handshake struct {
+	Type      HandshakeType
+	Version   Version
+	Random    [32]byte
+	SessionID []byte
+	Tail      Byter
+}
+
+func (h *Handshake) Bytes() []byte {
+	buf := bytes.Buffer{}
+	packetBuf := bytes.Buffer{}
+
+	buf.WriteByte(byte(h.Type))
+
+	packetBuf.Write(h.Version.Bytes())
+	packetBuf.Write(h.Random[:])
+	packetBuf.WriteByte(byte(len(h.SessionID)))
+	packetBuf.Write(h.SessionID)
+	packetBuf.Write(h.Tail.Bytes())
+
+	sizeUint24 := utils.ToUint24(uint32(packetBuf.Len()))
+	sizeUint24Bytes := sizeUint24[:]
+	sizeUint24Bytes[0], sizeUint24Bytes[2] = sizeUint24Bytes[2], sizeUint24Bytes[0]
+
+	buf.Write(sizeUint24Bytes)
+	packetBuf.WriteTo(&buf) // nolint: errcheck
+
+	return buf.Bytes()
+}

tlstypes/record.go

@@ -0,0 +1,85 @@
+package tlstypes
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+const recordMaxChunkSize = 16384 + 24
+
+type Record struct {
+	Type    RecordType
+	Version Version
+	Data    Byter
+}
+
+func (r Record) Bytes() []byte {
+	buf := bytes.Buffer{}
+	data := r.Data.Bytes()
+
+	buf.WriteByte(byte(r.Type))
+	buf.Write(r.Version.Bytes())
+	binary.Write(&buf, binary.BigEndian, uint16(len(data))) // nolint: errcheck
+	buf.Write(data)
+
+	return buf.Bytes()
+}
+
+func ReadRecord(reader io.Reader) (Record, error) {
+	buf := [2]byte{}
+	rec := Record{}
+
+	if _, err := io.ReadFull(reader, buf[:1]); err != nil {
+		return rec, fmt.Errorf("cannot read record type: %w", err)
+	}
+
+	rec.Type = RecordType(buf[0])
+
+	if _, err := io.ReadFull(reader, buf[:]); err != nil {
+		return rec, fmt.Errorf("cannot read version: %w", err)
+	}
+
+	switch {
+	case bytes.Equal(buf[:], Version13Bytes):
+		rec.Version = Version13
+	case bytes.Equal(buf[:], Version12Bytes):
+		rec.Version = Version12
+	case bytes.Equal(buf[:], Version11Bytes):
+		rec.Version = Version11
+	case bytes.Equal(buf[:], Version10Bytes):
+		rec.Version = Version10
+	}
+
+	if _, err := io.ReadFull(reader, buf[:]); err != nil {
+		return rec, fmt.Errorf("cannot read data length: %w", err)
+	}
+
+	data := make([]byte, binary.BigEndian.Uint16(buf[:]))
+	if _, err := io.ReadFull(reader, data); err != nil {
+		return rec, fmt.Errorf("cannot read data: %w", err)
+	}
+
+	rec.Data = RawBytes(data)
+
+	return rec, nil
+}
+
+func MakeRecords(raw []byte) (arr []Record) {
+	for len(raw) > 0 {
+		chunkSize := recordMaxChunkSize
+		if chunkSize > len(raw) {
+			chunkSize = len(raw)
+		}
+
+		arr = append(arr, Record{
+			Type:    RecordTypeApplicationData,
+			Version: Version12,
+			Data:    RawBytes(raw[:chunkSize]),
+		})
+		raw = raw[chunkSize:]
+	}
+
+	return
+}

tlstypes/server_hello.go

@@ -0,0 +1,92 @@
+package tlstypes
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"io"
+
+	"golang.org/x/crypto/curve25519"
+
+	"github.com/9seconds/mtg/config"
+)
+
+type ServerHello struct {
+	Handshake
+
+	clientHello *ClientHello
+}
+
+func (s ServerHello) WelcomePacket(hostCert []byte) []byte {
+	s.Random = [32]byte{}
+	rec := Record{
+		Type:    RecordTypeHandshake,
+		Version: Version12,
+		Data:    &s,
+	}
+	buf := bytes.NewBuffer(rec.Bytes())
+
+	recChangeCipher := Record{
+		Type:    RecordTypeChangeCipherSpec,
+		Version: Version12,
+		Data:    RawBytes([]byte{0x01}),
+	}
+	buf.Write(recChangeCipher.Bytes())
+
+	recData := Record{
+		Type:    RecordTypeApplicationData,
+		Version: Version12,
+		Data:    RawBytes(hostCert),
+	}
+	buf.Write(recData.Bytes())
+	packet := buf.Bytes()
+
+	mac := hmac.New(sha256.New, config.C.Secret)
+	mac.Write(s.clientHello.Random[:]) // nolint: errcheck
+	mac.Write(packet)                  // nolint: errcheck
+	copy(packet[11:], mac.Sum(nil))
+
+	return packet
+}
+
+func NewServerHello(clientHello *ClientHello) *ServerHello {
+	rv := &ServerHello{
+		clientHello: clientHello,
+	}
+
+	rv.Type = HandshakeTypeServer
+	rv.Version = Version12
+	rv.SessionID = make([]byte, len(clientHello.SessionID))
+	copy(rv.SessionID, clientHello.SessionID)
+
+	tail := bytes.NewBuffer(CipherSuiteType_TLS_AES_128_GCM_SHA256_Bytes)
+	tail.WriteByte(0x00) // no compression
+	makeTLSExtensions(tail)
+	rv.Tail = RawBytes(tail.Bytes())
+
+	return rv
+}
+
+func makeTLSExtensions(buf io.Writer) {
+	buf.Write([]byte{ // nolint: errcheck
+		0x00, 0x2e, // 46 bytes of data
+		0x00, 0x33, // Extension - Key Share
+		0x00, 0x24, // 36 bytes
+		0x00, 0x1d, // x25519 curve
+		0x00, 0x20, // 32 bytes of key
+	})
+
+	var dst, in, base [32]byte
+
+	rand.Read(in[:])   // nolint: errcheck
+	rand.Read(base[:]) // nolint: errcheck
+	curve25519.ScalarMult(&dst, &in, &base)
+	buf.Write(dst[:]) // nolint: errcheck
+
+	buf.Write([]byte{ // nolint: errcheck
+		0x00, 0x2b, // Extension - Supported Versions
+		0x00, 0x02, // 2 bytes are following
+		0x03, 0x04, // TLS 1.3
+	})
+}