QUIC sniffer: Full support for handling multiple initial packets (#4642)

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
Co-authored-by: Vigilans <vigilans@foxmail.com>
Co-authored-by: Shelikhoo <xiaokangwang@outlook.com>
Co-authored-by: dyhkwong <50692134+dyhkwong@users.noreply.github.com>

common/buf/buffer.go

@@ -15,6 +15,15 @@ const (
 
 var pool = bytespool.GetPool(Size)
 
+// ownership represents the data owner of the buffer.
+type ownership uint8
+
+const (
+	managed ownership = iota
+	unmanaged
+	bytespools
+)
+
 // Buffer is a recyclable allocation of a byte array. Buffer.Release() recycles
 // the buffer into an internal buffer pool, in order to recreate a buffer more
 // quickly.
@@ -22,11 +31,11 @@ type Buffer struct {
 	v         []byte
 	start     int32
 	end       int32
-	unmanaged bool
+	ownership ownership
 	UDP       *net.Destination
 }
 
-// New creates a Buffer with 0 length and 8K capacity.
+// New creates a Buffer with 0 length and 8K capacity, managed.
 func New() *Buffer {
 	buf := pool.Get().([]byte)
 	if cap(buf) >= Size {
@@ -40,7 +49,7 @@ func New() *Buffer {
 	}
 }
 
-// NewExisted creates a managed, standard size Buffer with an existed bytearray
+// NewExisted creates a standard size Buffer with an existed bytearray, managed.
 func NewExisted(b []byte) *Buffer {
 	if cap(b) < Size {
 		panic("Invalid buffer")
@@ -57,16 +66,16 @@ func NewExisted(b []byte) *Buffer {
 	}
 }
 
-// FromBytes creates a Buffer with an existed bytearray
+// FromBytes creates a Buffer with an existed bytearray, unmanaged.
 func FromBytes(b []byte) *Buffer {
 	return &Buffer{
 		v:         b,
 		end:       int32(len(b)),
-		unmanaged: true,
+		ownership: unmanaged,
 	}
 }
 
-// StackNew creates a new Buffer object on stack.
+// StackNew creates a new Buffer object on stack, managed.
 // This method is for buffers that is released in the same function.
 func StackNew() Buffer {
 	buf := pool.Get().([]byte)
@@ -81,9 +90,17 @@ func StackNew() Buffer {
 	}
 }
 
+// NewWithSize creates a Buffer with 0 length and capacity with at least the given size, bytespool's.
+func NewWithSize(size int32) *Buffer {
+	return &Buffer{
+		v:         bytespool.Alloc(size),
+		ownership: bytespools,
+	}
+}
+
 // Release recycles the buffer into an internal buffer pool.
 func (b *Buffer) Release() {
-	if b == nil || b.v == nil || b.unmanaged {
+	if b == nil || b.v == nil || b.ownership == unmanaged {
 		return
 	}
 
@@ -91,8 +108,13 @@ func (b *Buffer) Release() {
 	b.v = nil
 	b.Clear()
 
-	if cap(p) == Size {
-		pool.Put(p)
+	switch b.ownership {
+	case managed:
+		if cap(p) == Size {
+			pool.Put(p)
+		}
+	case bytespools:
+		bytespool.Free(p)
 	}
 	b.UDP = nil
 }
@@ -215,13 +237,6 @@ func (b *Buffer) Cap() int32 {
 	return int32(len(b.v))
 }
 
-// NewWithSize creates a Buffer with 0 length and capacity with at least the given size.
-func NewWithSize(size int32) *Buffer {
-	return &Buffer{
-		v: bytespool.Alloc(size),
-	}
-}
-
 // IsEmpty returns true if the buffer is empty.
 func (b *Buffer) IsEmpty() bool {
 	return b.Len() == 0