TUN-6035: Reduce buffer size when proxying data

cfio/copy.go

@@ -0,0 +1,27 @@
+package cfio
+
+import (
+	"io"
+	"sync"
+)
+
+const defaultBufferSize = 16 * 1024
+
+var bufferPool = sync.Pool{
+	New: func() interface{} {
+		return make([]byte, defaultBufferSize)
+	},
+}
+
+func Copy(dst io.Writer, src io.Reader) (written int64, err error) {
+	_, okWriteTo := src.(io.WriterTo)
+	_, okReadFrom := dst.(io.ReaderFrom)
+	var buffer []byte = nil
+
+	if !(okWriteTo || okReadFrom) {
+		buffer = bufferPool.Get().([]byte)
+		defer bufferPool.Put(buffer)
+	}
+
+	return io.CopyBuffer(dst, src, buffer)
+}

websocket/websocket.go

@@ -15,6 +15,8 @@ import (
 	"github.com/getsentry/raven-go"
 	"github.com/gorilla/websocket"
 	"github.com/rs/zerolog"
+
+	"github.com/cloudflare/cloudflared/cfio"
 )
 
 // IsWebSocketUpgrade checks to see if the request is a WebSocket connection.
@@ -146,7 +148,7 @@ func copyData(dst io.Writer, src io.Reader, dir string) (written int64, err erro
 		}
 		return copyBuffer(dst, src, dir)
 	} else {
-		return io.Copy(dst, src)
+		return cfio.Copy(dst, src)
 	}
 }