// Package proxy provides a network Proxy interface and implementations for TCP // and UDP. package proxy import ( "fmt" "net" ) // Proxy defines the behavior of a proxy. It forwards traffic back and forth // between two endpoints : the frontend and the backend. // It can be used to do software port-mapping between two addresses. // e.g. forward all traffic between the frontend (host) 127.0.0.1:3000 // to the backend (container) at 172.17.42.108:4000. type Proxy interface { // Run starts forwarding traffic back and forth between the front // and back-end addresses. Run() // Close stops forwarding traffic and close both ends of the Proxy. Close() // FrontendAddr returns the address on which the proxy is listening. FrontendAddr() net.Addr // BackendAddr returns the proxied address. BackendAddr() net.Addr } // NewProxy creates a Proxy according to the specified frontendAddr and backendAddr. func NewProxy(frontendAddr, backendAddr net.Addr) (Proxy, error) { switch frontendAddr.(type) { case *net.UDPAddr: return NewUDPProxy(frontendAddr.(*net.UDPAddr), backendAddr.(*net.UDPAddr)) case *net.TCPAddr: return NewTCPProxy(frontendAddr.(*net.TCPAddr), backendAddr.(*net.TCPAddr)) default: panic(fmt.Errorf("Unsupported protocol")) } }