Add domain sniffer

common/sniff/quic.go

@@ -0,0 +1,187 @@
+package sniff
+
+import (
+	"bytes"
+	"context"
+	"crypto"
+	"crypto/aes"
+	"encoding/binary"
+	"io"
+	"os"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/sniff/internal/qtls"
+	C "github.com/sagernet/sing-box/constant"
+	"golang.org/x/crypto/hkdf"
+)
+
+func QUICClientHello(ctx context.Context, packet []byte) (*adapter.InboundContext, error) {
+	reader := bytes.NewReader(packet)
+
+	typeByte, err := reader.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+
+	if typeByte&0x80 == 0 || typeByte&0x40 == 0 {
+		return nil, os.ErrInvalid
+	}
+	var versionNumber uint32
+	err = binary.Read(reader, binary.BigEndian, &versionNumber)
+	if err != nil {
+		return nil, err
+	}
+	if versionNumber != qtls.VersionDraft29 && versionNumber != qtls.Version1 && versionNumber != qtls.Version2 {
+		return nil, os.ErrInvalid
+	}
+	if (typeByte&0x30)>>4 == 0x0 {
+	} else if (typeByte&0x30)>>4 != 0x01 {
+		// 0-rtt
+	} else {
+		return nil, os.ErrInvalid
+	}
+
+	destConnIDLen, err := reader.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+
+	destConnID := make([]byte, destConnIDLen)
+	_, err = io.ReadFull(reader, destConnID)
+	if err != nil {
+		return nil, err
+	}
+
+	srcConnIDLen, err := reader.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = io.CopyN(io.Discard, reader, int64(srcConnIDLen))
+	if err != nil {
+		return nil, err
+	}
+
+	tokenLen, err := qtls.ReadUvarint(reader)
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = io.CopyN(io.Discard, reader, int64(tokenLen))
+	if err != nil {
+		return nil, err
+	}
+
+	packetLen, err := qtls.ReadUvarint(reader)
+	if err != nil {
+		return nil, err
+	}
+
+	hdrLen := int(reader.Size()) - reader.Len()
+	if hdrLen != len(packet)-int(packetLen) {
+		return nil, os.ErrInvalid
+	}
+
+	_, err = io.CopyN(io.Discard, reader, 4)
+	if err != nil {
+		return nil, err
+	}
+
+	pnBytes := make([]byte, aes.BlockSize)
+	_, err = io.ReadFull(reader, pnBytes)
+	if err != nil {
+		return nil, err
+	}
+
+	var salt []byte
+	switch versionNumber {
+	case qtls.Version1:
+		salt = qtls.SaltV1
+	case qtls.Version2:
+		salt = qtls.SaltV2
+	default:
+		salt = qtls.SaltOld
+	}
+	var hkdfHeaderProtectionLabel string
+	switch versionNumber {
+	case qtls.Version2:
+		hkdfHeaderProtectionLabel = qtls.HKDFLabelHeaderProtectionV2
+	default:
+		hkdfHeaderProtectionLabel = qtls.HKDFLabelHeaderProtectionV1
+	}
+	initialSecret := hkdf.Extract(crypto.SHA256.New, destConnID, salt)
+	secret := qtls.HKDFExpandLabel(crypto.SHA256, initialSecret, []byte{}, "client in", crypto.SHA256.Size())
+	hpKey := qtls.HKDFExpandLabel(crypto.SHA256, secret, []byte{}, hkdfHeaderProtectionLabel, 16)
+	block, err := aes.NewCipher(hpKey)
+	if err != nil {
+		return nil, err
+	}
+	mask := make([]byte, aes.BlockSize)
+	block.Encrypt(mask, pnBytes)
+	newPacket := make([]byte, len(packet))
+	copy(newPacket, packet)
+	newPacket[0] ^= mask[0] & 0xf
+	for i := range newPacket[hdrLen : hdrLen+4] {
+		newPacket[hdrLen+i] ^= mask[i+1]
+	}
+	packetNumberLength := newPacket[0]&0x3 + 1
+	if packetNumberLength != 1 {
+		return nil, os.ErrInvalid
+	}
+	packetNumber := newPacket[hdrLen]
+	if err != nil {
+		return nil, err
+	}
+	if packetNumber != 0 {
+		return nil, os.ErrInvalid
+	}
+
+	extHdrLen := hdrLen + int(packetNumberLength)
+	copy(newPacket[extHdrLen:hdrLen+4], packet[extHdrLen:])
+	data := newPacket[extHdrLen : int(packetLen)+hdrLen]
+
+	var keyLabel string
+	var ivLabel string
+	switch versionNumber {
+	case qtls.Version2:
+		keyLabel = qtls.HKDFLabelKeyV2
+		ivLabel = qtls.HKDFLabelIVV2
+	default:
+		keyLabel = qtls.HKDFLabelKeyV1
+		ivLabel = qtls.HKDFLabelIVV1
+	}
+
+	key := qtls.HKDFExpandLabel(crypto.SHA256, secret, []byte{}, keyLabel, 16)
+	iv := qtls.HKDFExpandLabel(crypto.SHA256, secret, []byte{}, ivLabel, 12)
+	cipher := qtls.AEADAESGCMTLS13(key, iv)
+	nonce := make([]byte, int32(cipher.NonceSize()))
+	binary.BigEndian.PutUint64(nonce[len(nonce)-8:], uint64(packetNumber))
+	decrypted, err := cipher.Open(newPacket[extHdrLen:extHdrLen], nonce, data, newPacket[:extHdrLen])
+	if err != nil {
+		return nil, err
+	}
+	decryptedReader := bytes.NewReader(decrypted)
+	frameType, err := decryptedReader.ReadByte()
+	if frameType != 0x6 {
+		// not crypto frame
+		return &adapter.InboundContext{Protocol: C.ProtocolQUIC}, nil
+	}
+	_, err = qtls.ReadUvarint(decryptedReader)
+	if err != nil {
+		return nil, err
+	}
+	_, err = qtls.ReadUvarint(decryptedReader)
+	if err != nil {
+		return nil, err
+	}
+	tlsHdr := make([]byte, 5)
+	tlsHdr[0] = 0x16
+	binary.BigEndian.PutUint16(tlsHdr[1:], uint16(0x0303))
+	binary.BigEndian.PutUint16(tlsHdr[3:], uint16(decryptedReader.Len()))
+	metadata, err := TLSClientHello(ctx, io.MultiReader(bytes.NewReader(tlsHdr), decryptedReader))
+	if err != nil {
+		return nil, err
+	}
+	metadata.Protocol = C.ProtocolQUIC
+	return metadata, nil
+}