feat: nameserver-policy support use rule-providers and reduce domain-set memory

common/pool/buffer_standard.go

@@ -0,0 +1,15 @@
+//go:build !with_low_memory
+
+package pool
+
+const (
+	// io.Copy default buffer size is 32 KiB
+	// but the maximum packet size of vmess/shadowsocks is about 16 KiB
+	// so define a buffer of 20 KiB to reduce the memory of each TCP relay
+	RelayBufferSize = 20 * 1024
+
+	// RelayBufferSize uses 20KiB, but due to the allocator it will actually
+	// request 32Kib. Most UDPs are smaller than the MTU, and the TUN's MTU
+	// set to 9000, so the UDP Buffer size set to 16Kib
+	UDPBufferSize = 16 * 1024
+)