mirror of
https://github.com/XTLS/Xray-core.git
synced 2024-12-23 03:43:33 +02:00
298 lines
8.9 KiB
Go
298 lines
8.9 KiB
Go
package quic
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import (
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"context"
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"crypto"
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"crypto/aes"
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"crypto/tls"
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"encoding/binary"
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"io"
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"github.com/quic-go/quic-go/quicvarint"
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"github.com/xtls/xray-core/common"
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"github.com/xtls/xray-core/common/buf"
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"github.com/xtls/xray-core/common/bytespool"
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"github.com/xtls/xray-core/common/errors"
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ptls "github.com/xtls/xray-core/common/protocol/tls"
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"golang.org/x/crypto/hkdf"
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)
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type SniffHeader struct {
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domain string
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}
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func (s SniffHeader) Protocol() string {
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return "quic"
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}
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func (s SniffHeader) Domain() string {
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return s.domain
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}
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const (
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versionDraft29 uint32 = 0xff00001d
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version1 uint32 = 0x1
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)
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var (
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quicSaltOld = []byte{0xaf, 0xbf, 0xec, 0x28, 0x99, 0x93, 0xd2, 0x4c, 0x9e, 0x97, 0x86, 0xf1, 0x9c, 0x61, 0x11, 0xe0, 0x43, 0x90, 0xa8, 0x99}
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quicSalt = []byte{0x38, 0x76, 0x2c, 0xf7, 0xf5, 0x59, 0x34, 0xb3, 0x4d, 0x17, 0x9a, 0xe6, 0xa4, 0xc8, 0x0c, 0xad, 0xcc, 0xbb, 0x7f, 0x0a}
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initialSuite = &CipherSuiteTLS13{
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ID: tls.TLS_AES_128_GCM_SHA256,
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KeyLen: 16,
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AEAD: AEADAESGCMTLS13,
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Hash: crypto.SHA256,
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}
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errNotQuic = errors.New("not quic")
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errNotQuicInitial = errors.New("not initial packet")
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)
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func SniffQUIC(b []byte) (resultReturn *SniffHeader, errorReturn error) {
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// In extremely rare cases, this sniffer may cause slice error
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// and we set recover() here to prevent crash.
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// TODO: Thoroughly fix this panic
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defer func() {
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if r := recover(); r != nil {
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errors.LogError(context.Background(), "Failed to sniff QUIC: ", r)
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resultReturn = nil
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errorReturn = common.ErrNoClue
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}
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}()
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// Crypto data separated across packets
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cryptoLen := 0
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cryptoData := bytespool.Alloc(int32(len(b)))
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defer bytespool.Free(cryptoData)
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// Parse QUIC packets
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for len(b) > 0 {
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buffer := buf.FromBytes(b)
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typeByte, err := buffer.ReadByte()
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if err != nil {
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return nil, errNotQuic
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}
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isLongHeader := typeByte&0x80 > 0
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if !isLongHeader || typeByte&0x40 == 0 {
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return nil, errNotQuicInitial
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}
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vb, err := buffer.ReadBytes(4)
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if err != nil {
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return nil, errNotQuic
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}
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versionNumber := binary.BigEndian.Uint32(vb)
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if versionNumber != 0 && typeByte&0x40 == 0 {
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return nil, errNotQuic
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} else if versionNumber != versionDraft29 && versionNumber != version1 {
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return nil, errNotQuic
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}
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packetType := (typeByte & 0x30) >> 4
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isQuicInitial := packetType == 0x0
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var destConnID []byte
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if l, err := buffer.ReadByte(); err != nil {
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return nil, errNotQuic
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} else if destConnID, err = buffer.ReadBytes(int32(l)); err != nil {
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return nil, errNotQuic
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}
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if l, err := buffer.ReadByte(); err != nil {
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return nil, errNotQuic
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} else if common.Error2(buffer.ReadBytes(int32(l))) != nil {
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return nil, errNotQuic
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}
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tokenLen, err := quicvarint.Read(buffer)
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if err != nil || tokenLen > uint64(len(b)) {
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return nil, errNotQuic
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}
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if _, err = buffer.ReadBytes(int32(tokenLen)); err != nil {
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return nil, errNotQuic
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}
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packetLen, err := quicvarint.Read(buffer)
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if err != nil {
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return nil, errNotQuic
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}
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hdrLen := len(b) - int(buffer.Len())
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if len(b) < hdrLen+int(packetLen) {
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return nil, common.ErrNoClue // Not enough data to read as a QUIC packet. QUIC is UDP-based, so this is unlikely to happen.
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}
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restPayload := b[hdrLen+int(packetLen):]
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if !isQuicInitial { // Skip this packet if it's not initial packet
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b = restPayload
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continue
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}
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origPNBytes := make([]byte, 4)
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copy(origPNBytes, b[hdrLen:hdrLen+4])
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var salt []byte
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if versionNumber == version1 {
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salt = quicSalt
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} else {
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salt = quicSaltOld
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}
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initialSecret := hkdf.Extract(crypto.SHA256.New, destConnID, salt)
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secret := hkdfExpandLabel(crypto.SHA256, initialSecret, []byte{}, "client in", crypto.SHA256.Size())
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hpKey := hkdfExpandLabel(initialSuite.Hash, secret, []byte{}, "quic hp", initialSuite.KeyLen)
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block, err := aes.NewCipher(hpKey)
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if err != nil {
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return nil, err
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}
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cache := buf.New()
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defer cache.Release()
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mask := cache.Extend(int32(block.BlockSize()))
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block.Encrypt(mask, b[hdrLen+4:hdrLen+4+16])
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b[0] ^= mask[0] & 0xf
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for i := range b[hdrLen : hdrLen+4] {
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b[hdrLen+i] ^= mask[i+1]
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}
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packetNumberLength := b[0]&0x3 + 1
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if packetNumberLength != 1 {
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return nil, errNotQuicInitial
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}
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var packetNumber uint32
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{
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n, err := buffer.ReadByte()
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if err != nil {
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return nil, err
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}
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packetNumber = uint32(n)
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}
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extHdrLen := hdrLen + int(packetNumberLength)
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copy(b[extHdrLen:hdrLen+4], origPNBytes[packetNumberLength:])
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data := b[extHdrLen : int(packetLen)+hdrLen]
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key := hkdfExpandLabel(crypto.SHA256, secret, []byte{}, "quic key", 16)
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iv := hkdfExpandLabel(crypto.SHA256, secret, []byte{}, "quic iv", 12)
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cipher := AEADAESGCMTLS13(key, iv)
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nonce := cache.Extend(int32(cipher.NonceSize()))
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binary.BigEndian.PutUint64(nonce[len(nonce)-8:], uint64(packetNumber))
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decrypted, err := cipher.Open(b[extHdrLen:extHdrLen], nonce, data, b[:extHdrLen])
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if err != nil {
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return nil, err
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}
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buffer = buf.FromBytes(decrypted)
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for i := 0; !buffer.IsEmpty(); i++ {
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frameType := byte(0x0) // Default to PADDING frame
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for frameType == 0x0 && !buffer.IsEmpty() {
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frameType, _ = buffer.ReadByte()
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}
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switch frameType {
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case 0x00: // PADDING frame
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case 0x01: // PING frame
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case 0x02, 0x03: // ACK frame
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if _, err = quicvarint.Read(buffer); err != nil { // Field: Largest Acknowledged
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return nil, io.ErrUnexpectedEOF
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}
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if _, err = quicvarint.Read(buffer); err != nil { // Field: ACK Delay
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return nil, io.ErrUnexpectedEOF
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}
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ackRangeCount, err := quicvarint.Read(buffer) // Field: ACK Range Count
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if err != nil {
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return nil, io.ErrUnexpectedEOF
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}
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if _, err = quicvarint.Read(buffer); err != nil { // Field: First ACK Range
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return nil, io.ErrUnexpectedEOF
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}
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for i := 0; i < int(ackRangeCount); i++ { // Field: ACK Range
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if _, err = quicvarint.Read(buffer); err != nil { // Field: ACK Range -> Gap
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return nil, io.ErrUnexpectedEOF
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}
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if _, err = quicvarint.Read(buffer); err != nil { // Field: ACK Range -> ACK Range Length
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return nil, io.ErrUnexpectedEOF
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}
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}
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if frameType == 0x03 {
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if _, err = quicvarint.Read(buffer); err != nil { // Field: ECN Counts -> ECT0 Count
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return nil, io.ErrUnexpectedEOF
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}
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if _, err = quicvarint.Read(buffer); err != nil { // Field: ECN Counts -> ECT1 Count
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return nil, io.ErrUnexpectedEOF
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}
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if _, err = quicvarint.Read(buffer); err != nil { //nolint:misspell // Field: ECN Counts -> ECT-CE Count
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return nil, io.ErrUnexpectedEOF
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}
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}
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case 0x06: // CRYPTO frame, we will use this frame
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offset, err := quicvarint.Read(buffer) // Field: Offset
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if err != nil {
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return nil, io.ErrUnexpectedEOF
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}
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length, err := quicvarint.Read(buffer) // Field: Length
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if err != nil || length > uint64(buffer.Len()) {
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return nil, io.ErrUnexpectedEOF
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}
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if cryptoLen < int(offset+length) {
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cryptoLen = int(offset + length)
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if len(cryptoData) < cryptoLen {
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newCryptoData := bytespool.Alloc(int32(cryptoLen))
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copy(newCryptoData, cryptoData)
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bytespool.Free(cryptoData)
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cryptoData = newCryptoData
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}
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}
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if _, err := buffer.Read(cryptoData[offset : offset+length]); err != nil { // Field: Crypto Data
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return nil, io.ErrUnexpectedEOF
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}
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case 0x1c: // CONNECTION_CLOSE frame, only 0x1c is permitted in initial packet
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if _, err = quicvarint.Read(buffer); err != nil { // Field: Error Code
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return nil, io.ErrUnexpectedEOF
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}
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if _, err = quicvarint.Read(buffer); err != nil { // Field: Frame Type
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return nil, io.ErrUnexpectedEOF
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}
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length, err := quicvarint.Read(buffer) // Field: Reason Phrase Length
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if err != nil {
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return nil, io.ErrUnexpectedEOF
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}
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if _, err := buffer.ReadBytes(int32(length)); err != nil { // Field: Reason Phrase
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return nil, io.ErrUnexpectedEOF
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}
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default:
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// Only above frame types are permitted in initial packet.
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// See https://www.rfc-editor.org/rfc/rfc9000.html#section-17.2.2-8
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return nil, errNotQuicInitial
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}
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}
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tlsHdr := &ptls.SniffHeader{}
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err = ptls.ReadClientHello(cryptoData[:cryptoLen], tlsHdr)
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if err != nil {
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// The crypto data may have not been fully recovered in current packets,
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// So we continue to sniff rest packets.
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b = restPayload
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continue
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}
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return &SniffHeader{domain: tlsHdr.Domain()}, nil
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}
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return nil, common.ErrNoClue
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}
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func hkdfExpandLabel(hash crypto.Hash, secret, context []byte, label string, length int) []byte {
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b := make([]byte, 3, 3+6+len(label)+1+len(context))
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binary.BigEndian.PutUint16(b, uint16(length))
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b[2] = uint8(6 + len(label))
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b = append(b, []byte("tls13 ")...)
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b = append(b, []byte(label)...)
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b = b[:3+6+len(label)+1]
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b[3+6+len(label)] = uint8(len(context))
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b = append(b, context...)
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out := make([]byte, length)
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n, err := hkdf.Expand(hash.New, secret, b).Read(out)
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if err != nil || n != length {
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panic("quic: HKDF-Expand-Label invocation failed unexpectedly")
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}
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return out
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}
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