nets: new package with netdev redesign ideas

nets/nets.go

@@ -0,0 +1,200 @@
+package nets
+
+import (
+	"errors"
+	"net/netip"
+	"time"
+)
+
+//go:linkname UseNetdev net.useNetdev
+func UseNetdev(dev Stack)
+
+// GethostByName() errors
+var (
+	ErrHostUnknown = errors.New("host unknown")
+	ErrMalAddr     = errors.New("malformed address")
+)
+
+// Socket errors
+var (
+	ErrFamilyNotSupported   = errors.New("address family not supported")
+	ErrProtocolNotSupported = errors.New("socket protocol/type not supported")
+	ErrStartingDHCPClient   = errors.New("error starting DHPC client")
+	ErrNoMoreSockets        = errors.New("no more sockets")
+	ErrClosingSocket        = errors.New("error closing socket")
+)
+
+var (
+	ErrConnected         = errors.New("already connected")
+	ErrConnectFailed     = errors.New("connect failed")
+	ErrConnectTimeout    = errors.New("connect timed out")
+	ErrMissingSSID       = errors.New("missing WiFi SSID")
+	ErrAuthFailure       = errors.New("wifi authentication failure")
+	ErrAuthTypeNoGood    = errors.New("wifi authorization type not supported")
+	ErrConnectModeNoGood = errors.New("connect mode not supported")
+	ErrNotSupported      = errors.New("not supported")
+)
+
+const (
+	AF_INET       = 0x2
+	SOCK_STREAM   = 0x1
+	SOCK_DGRAM    = 0x2
+	SOL_SOCKET    = 0x1
+	SO_KEEPALIVE  = 0x9
+	SOL_TCP       = 0x6
+	TCP_KEEPINTVL = 0x5
+	IPPROTO_TCP   = 0x6
+	IPPROTO_UDP   = 0x11
+	// Made up, not a real IP protocol number.  This is used to create a
+	// TLS socket on the device, assuming the device supports mbed TLS.
+	IPPROTO_TLS = 0xFE
+	F_SETFL     = 0x4
+)
+
+// Link is the minimum interface that need be implemented by any network
+// device driver.
+type Link interface {
+	// HardwareAddr6 returns the device's 6-byte [MAC address], a.k.a EUI-48.
+	//
+	// [MAC address]: https://en.wikipedia.org/wiki/MAC_address
+	HardwareAddr6() ([6]byte, error)
+	LinkStatus() LinkStatus
+}
+
+type LinkWifi interface {
+	Link
+	// Connect device to network
+	NetConnect(params WifiParams) error
+	// Disconnect device from network
+	NetDisconnect()
+	// Notify to register callback for network events
+	NetNotify(cb func(Event))
+}
+
+type Stack interface {
+	// GetHostByName returns the IP address of either a hostname or IPv4
+	// address in standard dot notation
+	GetHostByName(name string) (netip.Addr, error)
+
+	// Addr returns IP address assigned to the interface, either by
+	// DHCP or statically
+	Addr() (netip.Addr, error)
+
+	// Berkely Sockets-like interface, Go-ified.  See man page for socket(2), etc.
+	Socket(domain int, stype int, protocol int) (int, error)
+	Bind(sockfd int, ip netip.AddrPort) error
+	Connect(sockfd int, host string, ip netip.AddrPort) error
+	Listen(sockfd int, backlog int) error
+	Accept(sockfd int, ip netip.AddrPort) (int, error)
+	Send(sockfd int, buf []byte, flags int, deadline time.Time) (int, error)
+	Recv(sockfd int, buf []byte, flags int, deadline time.Time) (int, error)
+	Close(sockfd int) error
+	SetSockOpt(sockfd int, level int, opt int, value interface{}) error
+}
+
+// Netdev is returned by `Probe` function.
+type Netdev interface {
+	LinkWifi
+	Stack
+}
+
+type WifiParams struct {
+	// Connect mode
+	ConnectMode ConnectMode
+
+	// SSID of Wifi AP
+	SSID string
+
+	// Passphrase of Wifi AP
+	Passphrase string
+
+	// Wifi authorization type
+	Auth AuthType
+
+	// Wifi country code as two-char string.  E.g. "XX" for world-wide,
+	// "US" for USA, etc.
+	CountryCode string
+}
+
+type Event int
+
+// Network events
+const (
+	// The device's network connection is now UP
+	EventNetUp Event = iota
+	// The device's network connection is now DOWN
+	EventNetDown
+)
+
+type ConnectMode int
+
+// Connect modes
+const (
+	ConnectModeSTA = iota // Connect as Wifi station (default)
+	ConnectModeAP         // Connect as Wifi Access Point
+)
+
+type AuthType int
+
+// Wifi authorization types.  Used when setting up an access point, or
+// connecting to an access point
+const (
+	AuthTypeWPA2      = iota // WPA2 authorization (default)
+	AuthTypeOpen             // No authorization required (open)
+	AuthTypeWPA              // WPA authorization
+	AuthTypeWPA2Mixed        // WPA2/WPA mixed authorization
+)
+
+type LinkStatus uint8
+
+const (
+	LinkDown LinkStatus = iota
+	LinkConnecting
+	LinkUp
+)
+
+type WifiAutoconnectParams struct {
+	WifiParams
+	// NOTE ON FIELDS BELOW: These fields seem like a leaky abstraction- they can
+	// be implemented as an external "AutoConnect" function that is called in
+	// a goroutine that performs auto connect and whatnot.
+
+	// Retries is how many attempts to connect before returning with a
+	// "Connect failed" error.  Zero means infinite retries.
+	Retries int // Probably should be implemented as a function
+
+	// Timeout duration for each connection attempt.  The default zero
+	// value means 10sec.
+	ConnectTimeout time.Duration
+
+	// Watchdog ticker duration.  On tick, the watchdog will check for
+	// downed connection or hardware fault and try to recover the
+	// connection.  Set to zero to disable watchodog.
+	WatchdogTimeout time.Duration
+}
+
+func StartWifiAutoconnect(dev Netdev, cfg WifiAutoconnectParams) error {
+	if dev == nil {
+		return ErrConnectModeNoGood
+	}
+	go func() {
+		// Wifi autoconnect algorithm in one place,
+		// no need to implement for every single netdever.
+	RECONNECT:
+		for i := 0; i < cfg.Retries; i++ {
+			err := dev.NetConnect(cfg.WifiParams)
+			if err != nil {
+				time.Sleep(cfg.ConnectTimeout)
+				goto RECONNECT
+			}
+			for cfg.WatchdogTimeout != 0 {
+				time.Sleep(cfg.WatchdogTimeout)
+				if dev.LinkStatus() == LinkDown {
+					i = 0
+					goto RECONNECT
+				}
+			}
+		}
+	}()
+	return nil
+}