287 lines
8.1 KiB
Go
287 lines
8.1 KiB
Go
package sniffer
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import (
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"crypto"
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"crypto/aes"
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"crypto/cipher"
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"encoding/binary"
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"errors"
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"io"
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"github.com/metacubex/mihomo/common/buf"
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"github.com/metacubex/mihomo/common/utils"
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C "github.com/metacubex/mihomo/constant"
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"github.com/metacubex/quic-go/quicvarint"
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"golang.org/x/crypto/hkdf"
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)
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// Modified from https://github.com/v2fly/v2ray-core/blob/master/common/protocol/quic/sniff.go
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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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errNotQuic = errors.New("not QUIC")
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errNotQuicInitial = errors.New("not QUIC initial packet")
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)
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type QuicSniffer struct {
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*BaseSniffer
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}
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func NewQuicSniffer(snifferConfig SnifferConfig) (*QuicSniffer, error) {
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ports := snifferConfig.Ports
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if len(ports) == 0 {
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ports = utils.IntRanges[uint16]{utils.NewRange[uint16](443, 443)}
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}
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return &QuicSniffer{
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BaseSniffer: NewBaseSniffer(ports, C.UDP),
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}, nil
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}
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func (quic QuicSniffer) Protocol() string {
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return "quic"
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}
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func (quic QuicSniffer) SupportNetwork() C.NetWork {
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return C.UDP
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}
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func (quic QuicSniffer) SniffData(b []byte) (string, error) {
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buffer := buf.As(b)
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typeByte, err := buffer.ReadByte()
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if err != nil {
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return "", 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 "", 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 "", 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 "", errNotQuic
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} else if versionNumber != versionDraft29 && versionNumber != version1 {
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return "", errNotQuic
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}
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if (typeByte&0x30)>>4 != 0x0 {
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return "", errNotQuicInitial
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}
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var destConnID []byte
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if l, err := buffer.ReadByte(); err != nil {
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return "", errNotQuic
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} else if destConnID, err = buffer.ReadBytes(int(l)); err != nil {
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return "", errNotQuic
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}
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if l, err := buffer.ReadByte(); err != nil {
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return "", errNotQuic
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} else if _, err := buffer.ReadBytes(int(l)); err != nil {
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return "", 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 "", errNotQuic
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}
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if _, err = buffer.ReadBytes(int(tokenLen)); err != nil {
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return "", 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 "", errNotQuic
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}
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hdrLen := len(b) - buffer.Len()
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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(crypto.SHA256, secret, []byte{}, "quic hp", 16)
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block, err := aes.NewCipher(hpKey)
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if err != nil {
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return "", err
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}
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cache := buf.NewPacket()
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defer cache.Release()
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mask := cache.Extend(block.BlockSize())
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block.Encrypt(mask, b[hdrLen+4:hdrLen+4+16])
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firstByte := b[0]
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// Encrypt/decrypt first byte.
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if isLongHeader {
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// Long header: 4 bits masked
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// High 4 bits are not protected.
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firstByte ^= mask[0] & 0x0f
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} else {
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// Short header: 5 bits masked
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// High 3 bits are not protected.
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firstByte ^= mask[0] & 0x1f
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}
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packetNumberLength := int(firstByte&0x3 + 1) // max = 4 (64-bit sequence number)
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extHdrLen := hdrLen + packetNumberLength
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// copy to avoid modify origin data
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extHdr := cache.Extend(extHdrLen)
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copy(extHdr, b)
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extHdr[0] = firstByte
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packetNumber := extHdr[hdrLen:extHdrLen]
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// Encrypt/decrypt packet number.
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for i := range packetNumber {
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packetNumber[i] ^= mask[1+i]
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}
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if packetNumber[0] != 0 && packetNumber[0] != 1 {
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return "", errNotQuicInitial
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}
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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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aesCipher, err := aes.NewCipher(key)
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if err != nil {
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return "", err
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}
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aead, err := cipher.NewGCM(aesCipher)
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if err != nil {
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return "", err
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}
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// We only decrypt once, so we do not need to XOR it back.
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// https://github.com/quic-go/qtls-go1-20/blob/e132a0e6cb45e20ac0b705454849a11d09ba5a54/cipher_suites.go#L496
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for i, b := range packetNumber {
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iv[len(iv)-len(packetNumber)+i] ^= b
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}
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dst := cache.Extend(len(data))
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decrypted, err := aead.Open(dst[:0], iv, data, extHdr)
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if err != nil {
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return "", err
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}
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buffer = buf.As(decrypted)
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cryptoLen := uint(0)
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cryptoData := cache.Extend(buffer.Len())
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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 "", 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 "", 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 "", 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 "", 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 "", 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 "", 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 "", 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 "", 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 "", 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 "", 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 "", io.ErrUnexpectedEOF
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}
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if cryptoLen < uint(offset+length) {
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cryptoLen = uint(offset + length)
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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 "", 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 "", 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 "", 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 "", io.ErrUnexpectedEOF
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}
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if _, err := buffer.ReadBytes(int(length)); err != nil { // Field: Reason Phrase
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return "", 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 "", errNotQuicInitial
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}
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}
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domain, err := ReadClientHello(cryptoData[:cryptoLen])
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if err != nil {
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return "", err
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}
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return *domain, nil
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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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