fix reader/writer for packet conn

common/buf/reader.go

@@ -7,6 +7,23 @@ import (
 	"v2ray.com/core/common/errors"
 )
 
+func readOneUDP(r io.Reader) (*Buffer, error) {
+	b := New()
+	for i := 0; i < 64; i++ {
+		_, err := b.ReadFrom(r)
+		if !b.IsEmpty() {
+			return b, nil
+		}
+		if err != nil {
+			b.Release()
+			return nil, err
+		}
+	}
+
+	b.Release()
+	return nil, newError("Reader returns too many empty payloads.")
+}
+
 func readOne(r io.Reader) (*Buffer, error) {
 	// Use an one-byte buffer to wait for incoming payload.
 	var firstByte [1]byte
@@ -152,3 +169,17 @@ func (r *SingleReader) ReadMultiBuffer() (MultiBuffer, error) {
 	}
 	return MultiBuffer{b}, nil
 }
+
+// PacketReader is a Reader that read one Buffer every time.
+type PacketReader struct {
+	io.Reader
+}
+
+// ReadMultiBuffer implements Reader.
+func (r *PacketReader) ReadMultiBuffer() (MultiBuffer, error) {
+	b, err := readOneUDP(r.Reader)
+	if err != nil {
+		return nil, err
+	}
+	return MultiBuffer{b}, nil
+}