wifi/espat, rtl8720dn, wifinina, net: modify to use Adapter interface

Signed-off-by: deadprogram <ron@hybridgroup.com>

net/adapter.go

@@ -0,0 +1,44 @@
+package net
+
+import (
+	"errors"
+	"time"
+)
+
+var (
+	ErrWiFiMissingSSID    = errors.New("missing SSID")
+	ErrWiFiConnectTimeout = errors.New("WiFi connect timeout")
+)
+
+// Adapter interface is used to communicate with the network adapter.
+type Adapter interface {
+	// functions used to connect/disconnect to/from an access point
+	ConnectToAccessPoint(ssid, pass string, timeout time.Duration) error
+	Disconnect() error
+	GetClientIP() (string, error)
+
+	// these functions are used once the adapter is connected to the network
+	GetDNS(domain string) (string, error)
+	ConnectTCPSocket(addr, port string) error
+	ConnectSSLSocket(addr, port string) error
+	ConnectUDPSocket(addr, sendport, listenport string) error
+	DisconnectSocket() error
+	StartSocketSend(size int) error
+	Write(b []byte) (n int, err error)
+	ReadSocket(b []byte) (n int, err error)
+	IsSocketDataAvailable() bool
+
+	// FIXME: this is really specific to espat, and maybe shouldn't be part
+	// of the driver interface
+	Response(timeout int) ([]byte, error)
+}
+
+var ActiveDevice Adapter
+
+func UseDriver(a Adapter) {
+	// TODO: rethink and refactor this
+	if ActiveDevice != nil {
+		panic("net.ActiveDevice is already set")
+	}
+	ActiveDevice = a
+}