step 1 to remove reference to net package

common/net/system.go

@@ -0,0 +1,35 @@
+package net
+
+import "net"
+
+var DialTCP = net.DialTCP
+var DialUDP = net.DialUDP
+
+var Listen = net.Listen
+var ListenTCP = net.ListenTCP
+var ListenUDP = net.ListenUDP
+
+var LookupIP = net.LookupIP
+
+var SplitHostPort = net.SplitHostPort
+
+type Addr = net.Addr
+type Conn = net.Conn
+
+type TCPAddr = net.TCPAddr
+type TCPConn = net.TCPConn
+
+type UDPAddr = net.UDPAddr
+type UDPConn = net.UDPConn
+
+type UnixConn = net.UnixConn
+
+type IP = net.IP
+
+type Error = net.Error
+type AddrError = net.AddrError
+
+type Dialer = net.Dialer
+type Listener = net.Listener
+type TCPListener = net.TCPListener
+type UDPListener = net.UDPListener