From 4432cc2253eef3d8645c7d2ee8f9527a5237c94c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=96=E7=95=8C?= <i@sekai.icu>
Date: Sun, 10 Jul 2022 07:52:33 +0800
Subject: [PATCH] Fix quic sniff irl

---
 common/sniff/quic.go  | 55 +++++++++++++++++++++++++++++++++----------
 common/sniff/sniff.go |  1 +
 2 files changed, 43 insertions(+), 13 deletions(-)

diff --git a/common/sniff/quic.go b/common/sniff/quic.go
index e7e7f71f..07bcbd6c 100644
--- a/common/sniff/quic.go
+++ b/common/sniff/quic.go
@@ -12,6 +12,7 @@ import (
 	"github.com/sagernet/sing-box/adapter"
 	"github.com/sagernet/sing-box/common/sniff/internal/qtls"
 	C "github.com/sagernet/sing-box/constant"
+	E "github.com/sagernet/sing/common/exceptions"
 
 	"golang.org/x/crypto/hkdf"
 )
@@ -25,7 +26,7 @@ func QUICClientHello(ctx context.Context, packet []byte) (*adapter.InboundContex
 	}
 
 	if typeByte&0x80 == 0 || typeByte&0x40 == 0 {
-		return nil, os.ErrInvalid
+		return nil, E.New("bad type byte")
 	}
 	var versionNumber uint32
 	err = binary.Read(reader, binary.BigEndian, &versionNumber)
@@ -33,13 +34,22 @@ func QUICClientHello(ctx context.Context, packet []byte) (*adapter.InboundContex
 		return nil, err
 	}
 	if versionNumber != qtls.VersionDraft29 && versionNumber != qtls.Version1 && versionNumber != qtls.Version2 {
-		return nil, os.ErrInvalid
+		return nil, E.New("bad version")
 	}
-	if (typeByte&0x30)>>4 == 0x0 {
-	} else if (typeByte&0x30)>>4 != 0x01 {
-		// 0-rtt
+	if versionNumber == qtls.Version2 {
+		if (typeByte&0x30)>>4 == 0b01 {
+		} else if (typeByte&0x30)>>4 != 0b10 {
+			// 0-rtt
+		} else {
+			return nil, E.New("bad packet type")
+		}
 	} else {
-		return nil, os.ErrInvalid
+		if (typeByte&0x30)>>4 == 0x0 {
+		} else if (typeByte&0x30)>>4 != 0x01 {
+			// 0-rtt
+		} else {
+			return nil, E.New("bad packet type")
+		}
 	}
 
 	destConnIDLen, err := reader.ReadByte()
@@ -47,6 +57,10 @@ func QUICClientHello(ctx context.Context, packet []byte) (*adapter.InboundContex
 		return nil, err
 	}
 
+	if destConnIDLen == 0 || destConnIDLen > 20 {
+		return nil, E.New("bad destination connection id length")
+	}
+
 	destConnID := make([]byte, destConnIDLen)
 	_, err = io.ReadFull(reader, destConnID)
 	if err != nil {
@@ -79,7 +93,7 @@ func QUICClientHello(ctx context.Context, packet []byte) (*adapter.InboundContex
 	}
 
 	hdrLen := int(reader.Size()) - reader.Len()
-	if hdrLen != len(packet)-int(packetLen) {
+	if hdrLen+int(packetLen) > len(packet) {
 		return nil, os.ErrInvalid
 	}
 
@@ -126,17 +140,25 @@ func QUICClientHello(ctx context.Context, packet []byte) (*adapter.InboundContex
 		newPacket[hdrLen+i] ^= mask[i+1]
 	}
 	packetNumberLength := newPacket[0]&0x3 + 1
-	if packetNumberLength != 1 {
+	if hdrLen+int(packetNumberLength) > int(packetLen)+hdrLen {
 		return nil, os.ErrInvalid
 	}
-	packetNumber := newPacket[hdrLen]
-	if err != nil {
-		return nil, err
+	var packetNumber uint32
+	switch packetNumberLength {
+	case 1:
+		packetNumber = uint32(newPacket[hdrLen])
+	case 2:
+		packetNumber = uint32(binary.BigEndian.Uint16(newPacket[hdrLen:]))
+	case 3:
+		packetNumber = uint32(newPacket[hdrLen+2]) | uint32(newPacket[hdrLen+1])<<8 | uint32(newPacket[hdrLen])<<16
+	case 4:
+		packetNumber = binary.BigEndian.Uint32(newPacket[hdrLen:])
+	default:
+		return nil, E.New("bad packet number length")
 	}
 	if packetNumber != 0 {
-		return nil, os.ErrInvalid
+		return nil, E.New("bad packet number: ", packetNumber)
 	}
-
 	extHdrLen := hdrLen + int(packetNumberLength)
 	copy(newPacket[extHdrLen:hdrLen+4], packet[extHdrLen:])
 	data := newPacket[extHdrLen : int(packetLen)+hdrLen]
@@ -166,6 +188,13 @@ func QUICClientHello(ctx context.Context, packet []byte) (*adapter.InboundContex
 	if err != nil {
 		return nil, err
 	}
+	for frameType == 0x0 {
+		// skip padding
+		frameType, err = decryptedReader.ReadByte()
+		if err != nil {
+			return nil, err
+		}
+	}
 	if frameType != 0x6 {
 		// not crypto frame
 		return &adapter.InboundContext{Protocol: C.ProtocolQUIC}, nil
diff --git a/common/sniff/sniff.go b/common/sniff/sniff.go
index 12055bed..c33cded9 100644
--- a/common/sniff/sniff.go
+++ b/common/sniff/sniff.go
@@ -28,6 +28,7 @@ func PeekPacket(ctx context.Context, packet []byte, sniffers ...PacketSniffer) (
 	for _, sniffer := range sniffers {
 		sniffMetadata, err := sniffer(ctx, packet)
 		if err != nil {
+			println(err.Error())
 			return nil, err
 		}
 		return sniffMetadata, nil