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QUIC sniffer: Optimize the code #4655

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Merged
RPRX merged 1 commit into from
Apr 29, 2025
Merged

QUIC sniffer: Optimize the code #4655

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2 changes: 1 addition & 1 deletion app/dispatcher/default.go
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ func (r *cachedReader) Cache(b *buf.Buffer, deadline time.Duration) error {
r.cache, _ = buf.MergeMulti(r.cache, mb)
}
b.Clear()
rawBytes := b.Extend(b.Cap())
rawBytes := b.Extend(min(r.cache.Len(), b.Cap()))
n := r.cache.Copy(rawBytes)
b.Resize(0, int32(n))
r.Unlock()
Expand Down
29 changes: 11 additions & 18 deletions common/protocol/quic/sniff.go
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,6 @@ import (
"github.com/quic-go/quic-go/quicvarint"
"github.com/xtls/xray-core/common"
"github.com/xtls/xray-core/common/buf"
"github.com/xtls/xray-core/common/bytespool"
"github.com/xtls/xray-core/common/errors"
"github.com/xtls/xray-core/common/protocol"
ptls "github.com/xtls/xray-core/common/protocol/tls"
Expand Down Expand Up @@ -53,9 +52,9 @@ func SniffQUIC(b []byte) (*SniffHeader, error) {
}

// Crypto data separated across packets
cryptoLen := 0
cryptoData := bytespool.Alloc(32767)
defer bytespool.Free(cryptoData)
cryptoLen := int32(0)
cryptoDataBuf := buf.NewWithSize(32767)
defer cryptoDataBuf.Release()
cache := buf.New()
defer cache.Release()

Expand Down Expand Up @@ -143,7 +142,7 @@ func SniffQUIC(b []byte) (*SniffHeader, error) {

cache.Clear()
mask := cache.Extend(int32(block.BlockSize()))
block.Encrypt(mask, b[hdrLen+4:hdrLen+4+16])
block.Encrypt(mask, b[hdrLen+4:hdrLen+4+len(mask)])
b[0] ^= mask[0] & 0xf
packetNumberLength := int(b[0]&0x3 + 1)
for i := range packetNumberLength {
Expand Down Expand Up @@ -217,15 +216,15 @@ func SniffQUIC(b []byte) (*SniffHeader, error) {
if err != nil || length > uint64(buffer.Len()) {
return nil, io.ErrUnexpectedEOF
}
if cryptoLen < int(offset+length) {
newCryptoLen := int(offset + length)
if len(cryptoData) < newCryptoLen {
currentCryptoLen := int32(offset + length)
if cryptoLen < currentCryptoLen {
if cryptoDataBuf.Cap() < currentCryptoLen {
return nil, io.ErrShortBuffer
}
wipeBytes(cryptoData[cryptoLen:newCryptoLen])
cryptoLen = newCryptoLen
cryptoDataBuf.Extend(currentCryptoLen - cryptoLen)
cryptoLen = currentCryptoLen
}
if _, err := buffer.Read(cryptoData[offset : offset+length]); err != nil { // Field: Crypto Data
if _, err := buffer.Read(cryptoDataBuf.BytesRange(int32(offset), currentCryptoLen)); err != nil { // Field: Crypto Data
return nil, io.ErrUnexpectedEOF
}
case 0x1c: // CONNECTION_CLOSE frame, only 0x1c is permitted in initial packet
Expand All @@ -250,7 +249,7 @@ func SniffQUIC(b []byte) (*SniffHeader, error) {
}

tlsHdr := &ptls.SniffHeader{}
err = ptls.ReadClientHello(cryptoData[:cryptoLen], tlsHdr)
err = ptls.ReadClientHello(cryptoDataBuf.BytesRange(0, cryptoLen), tlsHdr)
if err != nil {
// The crypto data may have not been fully recovered in current packets,
// So we continue to sniff rest packets.
Expand All @@ -263,12 +262,6 @@ func SniffQUIC(b []byte) (*SniffHeader, error) {
return nil, protocol.ErrProtoNeedMoreData
}

func wipeBytes(b []byte) {
for i := range len(b) {
b[i] = 0x0
}
}

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))
Expand Down