udp for shadowsocks

common/alloc/buffer.go

@@ -1,6 +1,7 @@
 package alloc
 
 import (
+	"io"
 	"sync"
 )
 
@@ -72,6 +73,19 @@ func (b *Buffer) Write(data []byte) (int, error) {
 	return len(data), nil
 }
 
+func (b *Buffer) Read(data []byte) (int, error) {
+	if b.Len() == 0 {
+		return 0, io.EOF
+	}
+	nBytes := copy(data, b.Value)
+	if nBytes == b.Len() {
+		b.Value = b.Value[:0]
+	} else {
+		b.Value = b.Value[nBytes:]
+	}
+	return nBytes, nil
+}
+
 type bufferPool struct {
 	chain     chan []byte
 	allocator *sync.Pool