Quic sniffer (#1074)

* Add quic sniffer

* Fix quic sniffer

* Add uTP sniffer

* rename buf pool membership status to unmanaged

* rename buf type adaptor into FromBytes

Co-authored-by: 世界 <i@sekai.icu>
Co-authored-by: Shelikhoo <xiaokangwang@outlook.com>

common/protocol/quic/sniff.go

@@ -0,0 +1,208 @@
+package quic
+
+import (
+	"crypto"
+	"crypto/aes"
+	"crypto/tls"
+	"encoding/binary"
+	"io"
+
+	"github.com/lucas-clemente/quic-go/quicvarint"
+	"golang.org/x/crypto/hkdf"
+
+	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/buf"
+	"github.com/xtls/xray-core/common/errors"
+	ptls "github.com/xtls/xray-core/common/protocol/tls"
+)
+
+type SniffHeader struct {
+	domain string
+}
+
+func (s SniffHeader) Protocol() string {
+	return "quic"
+}
+
+func (s SniffHeader) Domain() string {
+	return s.domain
+}
+
+const (
+	versionDraft29 uint32 = 0xff00001d
+	version1       uint32 = 0x1
+)
+
+var (
+	quicSaltOld  = []byte{0xaf, 0xbf, 0xec, 0x28, 0x99, 0x93, 0xd2, 0x4c, 0x9e, 0x97, 0x86, 0xf1, 0x9c, 0x61, 0x11, 0xe0, 0x43, 0x90, 0xa8, 0x99}
+	quicSalt     = []byte{0x38, 0x76, 0x2c, 0xf7, 0xf5, 0x59, 0x34, 0xb3, 0x4d, 0x17, 0x9a, 0xe6, 0xa4, 0xc8, 0x0c, 0xad, 0xcc, 0xbb, 0x7f, 0x0a}
+	initialSuite = &CipherSuiteTLS13{
+		ID:     tls.TLS_AES_128_GCM_SHA256,
+		KeyLen: 16,
+		AEAD:   AEADAESGCMTLS13,
+		Hash:   crypto.SHA256,
+	}
+	errNotQuic        = errors.New("not quic")
+	errNotQuicInitial = errors.New("not initial packet")
+)
+
+func SniffQUIC(b []byte) (*SniffHeader, error) {
+	buffer := buf.FromBytes(b)
+	typeByte, err := buffer.ReadByte()
+	if err != nil {
+		return nil, errNotQuic
+	}
+	isLongHeader := typeByte&0x80 > 0
+	if !isLongHeader || typeByte&0x40 == 0 {
+		return nil, errNotQuicInitial
+	}
+
+	vb, err := buffer.ReadBytes(4)
+	if err != nil {
+		return nil, errNotQuic
+	}
+
+	versionNumber := binary.BigEndian.Uint32(vb)
+
+	if versionNumber != 0 && typeByte&0x40 == 0 {
+		return nil, errNotQuic
+	} else if versionNumber != versionDraft29 && versionNumber != version1 {
+		return nil, errNotQuic
+	}
+
+	if (typeByte&0x30)>>4 != 0x0 {
+		return nil, errNotQuicInitial
+	}
+
+	var destConnID []byte
+	if l, err := buffer.ReadByte(); err != nil {
+		return nil, errNotQuic
+	} else if destConnID, err = buffer.ReadBytes(int32(l)); err != nil {
+		return nil, errNotQuic
+	}
+
+	if l, err := buffer.ReadByte(); err != nil {
+		return nil, errNotQuic
+	} else if common.Error2(buffer.ReadBytes(int32(l))) != nil {
+		return nil, errNotQuic
+	}
+
+	tokenLen, err := quicvarint.Read(buffer)
+	if err != nil || tokenLen > uint64(len(b)) {
+		return nil, errNotQuic
+	}
+
+	if _, err = buffer.ReadBytes(int32(tokenLen)); err != nil {
+		return nil, errNotQuic
+	}
+
+	packetLen, err := quicvarint.Read(buffer)
+	if err != nil {
+		return nil, errNotQuic
+	}
+
+	hdrLen := len(b) - int(buffer.Len())
+
+	origPNBytes := make([]byte, 4)
+	copy(origPNBytes, b[hdrLen:hdrLen+4])
+
+	var salt []byte
+	if versionNumber == version1 {
+		salt = quicSalt
+	} else {
+		salt = quicSaltOld
+	}
+	initialSecret := hkdf.Extract(crypto.SHA256.New, destConnID, salt)
+	secret := hkdfExpandLabel(crypto.SHA256, initialSecret, []byte{}, "client in", crypto.SHA256.Size())
+	hpKey := hkdfExpandLabel(initialSuite.Hash, secret, []byte{}, "quic hp", initialSuite.KeyLen)
+	block, err := aes.NewCipher(hpKey)
+	if err != nil {
+		return nil, err
+	}
+
+	cache := buf.New()
+	defer cache.Release()
+
+	mask := cache.Extend(int32(block.BlockSize()))
+	block.Encrypt(mask, b[hdrLen+4:hdrLen+4+16])
+	b[0] ^= mask[0] & 0xf
+	for i := range b[hdrLen : hdrLen+4] {
+		b[hdrLen+i] ^= mask[i+1]
+	}
+	packetNumberLength := b[0]&0x3 + 1
+	if packetNumberLength != 1 {
+		return nil, errNotQuicInitial
+	}
+	var packetNumber uint32
+	{
+		n, err := buffer.ReadByte()
+		if err != nil {
+			return nil, err
+		}
+		packetNumber = uint32(n)
+	}
+
+	if packetNumber != 0 {
+		return nil, errNotQuicInitial
+	}
+
+	extHdrLen := hdrLen + int(packetNumberLength)
+	copy(b[extHdrLen:hdrLen+4], origPNBytes[packetNumberLength:])
+	data := b[extHdrLen : int(packetLen)+hdrLen]
+
+	key := hkdfExpandLabel(crypto.SHA256, secret, []byte{}, "quic key", 16)
+	iv := hkdfExpandLabel(crypto.SHA256, secret, []byte{}, "quic iv", 12)
+	cipher := AEADAESGCMTLS13(key, iv)
+	nonce := cache.Extend(int32(cipher.NonceSize()))
+	binary.BigEndian.PutUint64(nonce[len(nonce)-8:], uint64(packetNumber))
+	decrypted, err := cipher.Open(b[extHdrLen:extHdrLen], nonce, data, b[:extHdrLen])
+	if err != nil {
+		return nil, err
+	}
+	buffer = buf.FromBytes(decrypted)
+	frameType, err := buffer.ReadByte()
+	if err != nil {
+		return nil, io.ErrUnexpectedEOF
+	}
+	if frameType != 0x6 {
+		// not crypto frame
+		return &SniffHeader{domain: ""}, nil
+	}
+	if common.Error2(quicvarint.Read(buffer)) != nil {
+		return nil, io.ErrUnexpectedEOF
+	}
+	dataLen, err := quicvarint.Read(buffer)
+	if err != nil {
+		return nil, io.ErrUnexpectedEOF
+	}
+	if dataLen > uint64(buffer.Len()) {
+		return nil, io.ErrUnexpectedEOF
+	}
+	frameData, err := buffer.ReadBytes(int32(dataLen))
+	common.Must(err)
+	tlsHdr := &ptls.SniffHeader{}
+	err = ptls.ReadClientHello(frameData, tlsHdr)
+	if err != nil {
+		return nil, err
+	}
+
+	return &SniffHeader{domain: tlsHdr.Domain()}, nil
+}
+
+func hkdfExpandLabel(hash crypto.Hash, secret, context []byte, label string, length int) []byte {
+	b := make([]byte, 3, 3+6+len(label)+1+len(context))
+	binary.BigEndian.PutUint16(b, uint16(length))
+	b[2] = uint8(6 + len(label))
+	b = append(b, []byte("tls13 ")...)
+	b = append(b, []byte(label)...)
+	b = b[:3+6+len(label)+1]
+	b[3+6+len(label)] = uint8(len(context))
+	b = append(b, context...)
+
+	out := make([]byte, length)
+	n, err := hkdf.Expand(hash.New, secret, b).Read(out)
+	if err != nil || n != length {
+		panic("quic: HKDF-Expand-Label invocation failed unexpectedly")
+	}
+	return out
+}