WIP

Change-Id: I242111289aeb0c9a0ff843d698bc26168e336165
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscaled/tailscaled.go

@@ -75,6 +75,9 @@ import (
 
 // defaultTunName returns the default tun device name for the platform.
 func defaultTunName() string {
+	if runtime.GOOS == "linux" && distro.Get() == distro.ISH {
+		return "userspace-networking"
+	}
 	switch runtime.GOOS {
 	case "openbsd":
 		return "tun"
@@ -207,6 +210,8 @@ func main() {
 		os.Args = []string{"tailscaled", "be-child", "plan9-netshell"}
 	}
 
+	println("XX distro:", distro.Get())
+
 	if len(os.Args) > 1 {
 		sub := os.Args[1]
 		if fp, ok := subCommands[sub]; ok {

net/netmon/netmon.go

@@ -9,6 +9,7 @@ package netmon
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"net/netip"
 	"runtime"
 	"sync"
@@ -18,6 +19,7 @@ import (
 	"tailscale.com/util/clientmetric"
 	"tailscale.com/util/eventbus"
 	"tailscale.com/util/set"
+	"tailscale.com/version/distro"
 )
 
 // pollWallTimeInterval is how often we check the time to check
@@ -118,6 +120,9 @@ type ChangeDelta struct {
 // The returned monitor is inactive until it's started by the Start method.
 // Use RegisterChangeCallback to get notified of network changes.
 func New(bus *eventbus.Bus, logf logger.Logf) (*Monitor, error) {
+	if distro.Get() == distro.ISH {
+		return NewStatic(), nil // netlink doesn't work in iSH
+	}
 	logf = logger.WithPrefix(logf, "monitor: ")
 	m := &Monitor{
 		logf:     logf,
@@ -129,7 +134,7 @@ func New(bus *eventbus.Bus, logf logger.Logf) (*Monitor, error) {
 	m.changed = eventbus.Publish[*ChangeDelta](m.b)
 	st, err := m.interfaceStateUncached()
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("interface state: %w", err)
 	}
 	m.ifState = st
 

net/netmon/netmon_linux.go

@@ -17,6 +17,7 @@ import (
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/types/logger"
 	"tailscale.com/util/eventbus"
+	"tailscale.com/version/distro"
 )
 
 var debugNetlinkMessages = envknob.RegisterBool("TS_DEBUG_NETLINK")
@@ -57,6 +58,10 @@ type nlConn struct {
 }
 
 func newOSMon(bus *eventbus.Bus, logf logger.Logf, m *Monitor) (osMon, error) {
+	if distro.Get() == distro.ISH {
+		println("XXX hi from ish")
+		return newPollingMon(logf, m)
+	}
 	conn, err := netlink.Dial(unix.NETLINK_ROUTE, &netlink.Config{
 		// Routes get us most of the events of interest, but we need
 		// address as well to cover things like DHCP deciding to give

version/distro/distro.go

@@ -33,6 +33,7 @@ const (
 	Alpine    = Distro("alpine")
 	UBNT      = Distro("ubnt") // Ubiquiti Networks
 	JetKVM    = Distro("jetkvm")
+	ISH       = Distro("ish") // iOS iSH app
 )
 
 var distro lazy.SyncValue[Distro]
@@ -102,6 +103,11 @@ func linuxDistro() Distro {
 		return WDMyCloud
 	case have("/etc/unraid-version"):
 		return Unraid
+	case runtime.GOARCH == "386":
+		v, _ := os.ReadFile("/proc/cpuinfo")
+		if bytes.Contains(v, []byte(": iSH")) {
+			return ISH
+		}
 	case have("/etc/alpine-release"):
 		return Alpine
 	case runtime.GOARCH == "arm" && isDeviceModel("JetKVM"):