more plan9 fixes, to be cleaned up and merged separately later

Change-Id: I4c89609d7eb83bbe208aa87025365427d961b048
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

net/dns/manager_default.go

@@ -1,7 +1,7 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
-//go:build !linux && !freebsd && !openbsd && !windows && !darwin && !illumos && !solaris
+//go:build !linux && !freebsd && !openbsd && !windows && !darwin && !illumos && !solaris && !plan9
 
 package dns
 

net/dns/manager_plan9.go

@@ -0,0 +1,79 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// TODO: man 6 ndb | grep -e 'suffix.*same line'
+// to detect Russ's https://9fans.topicbox.com/groups/9fans/T9c9d81b5801a0820/ndb-suffix-specific-dns-changes
+
+package dns
+
+import (
+	"bufio"
+	"bytes"
+	"log"
+	"net/netip"
+	"os"
+	"regexp"
+
+	"tailscale.com/control/controlknobs"
+	"tailscale.com/health"
+	"tailscale.com/types/logger"
+)
+
+func NewOSConfigurator(logf logger.Logf, ht *health.Tracker, knobs *controlknobs.Knobs, interfaceName string) (OSConfigurator, error) {
+	return &plan9DNSManager{
+		logf:  logf,
+		ht:    ht,
+		knobs: knobs,
+	}, nil
+}
+
+type plan9DNSManager struct {
+	logf  logger.Logf
+	ht    *health.Tracker
+	knobs *controlknobs.Knobs
+}
+
+func (m *plan9DNSManager) SetDNS(c OSConfig) error {
+	var buf bytes.Buffer
+	bw := bufio.NewWriter(&buf)
+	c.WriteToBufioWriter(bw)
+	bw.Flush()
+
+	log.Printf("XXX: TODO: plan9 SetDNS: %s", buf.Bytes())
+	return nil
+}
+
+func (m *plan9DNSManager) SupportsSplitDNS() bool { return false }
+
+func (m *plan9DNSManager) Close() error {
+	// TODO(bradfitz): remove the Tailscale bits from /net/ndb ideally
+	return nil
+}
+
+var dnsRegex = regexp.MustCompile(`\bdns=(\d+\.\d+\.\d+\.\d+)\b`)
+
+func (m *plan9DNSManager) GetBaseConfig() (OSConfig, error) {
+	var oc OSConfig
+	f, err := os.Open("/net/ndb")
+	if err != nil {
+		return oc, err
+	}
+	defer f.Close()
+	bs := bufio.NewScanner(f)
+	for bs.Scan() {
+		m := dnsRegex.FindSubmatch(bs.Bytes())
+		if m == nil {
+			continue
+		}
+		addr, err := netip.ParseAddr(string(m[1]))
+		if err != nil {
+			continue
+		}
+		oc.Nameservers = append(oc.Nameservers, addr)
+	}
+	if err := bs.Err(); err != nil {
+		return oc, err
+	}
+
+	return oc, nil
+}

net/netmon/interfaces_test.go

@@ -13,7 +13,7 @@ import (
 )
 
 func TestGetState(t *testing.T) {
-	st, err := GetState()
+	st, err := GetState("")
 	if err != nil {
 		t.Fatal(err)
 	}

net/netmon/netmon.go

@@ -161,7 +161,7 @@ func (m *Monitor) InterfaceState() *State {
 }
 
 func (m *Monitor) interfaceStateUncached() (*State, error) {
-	return GetState()
+	return GetState(m.tsIfName)
 }
 
 // SetTailscaleInterfaceName sets the name of the Tailscale interface. For
@@ -491,7 +491,7 @@ func (m *Monitor) IsMajorChangeFrom(s1, s2 *State) bool {
 		return true
 	}
 	for iname, i := range s1.Interface {
-		if iname == m.tsIfName {
+		if iname == m.tsIfName || iname == "/net/ipifc/2" {
 			// Ignore changes in the Tailscale interface itself.
 			continue
 		}
@@ -596,7 +596,7 @@ func (m *Monitor) pollWallTime() {
 //
 // We don't do this on mobile platforms for battery reasons, and because these
 // platforms don't really sleep in the same way.
-const shouldMonitorTimeJump = runtime.GOOS != "android" && runtime.GOOS != "ios"
+const shouldMonitorTimeJump = runtime.GOOS != "android" && runtime.GOOS != "ios" && runtime.GOOS != "plan9"
 
 // checkWallTimeAdvanceLocked reports whether wall time jumped more than 150% of
 // pollWallTimeInterval, indicating we probably just came out of sleep. Once a

net/netmon/state.go

@@ -454,6 +454,9 @@ func isTailscaleInterface(name string, ips []netip.Prefix) bool {
 		// macOS NetworkExtensions and utun devices.
 		return true
 	}
+	if runtime.GOOS == "plan9" && (hasTailscaleIP(ips) || name == "/net/ipifc/2") { // XXX fix; use tun name
+		return true
+	}
 	return name == "Tailscale" || // as it is on Windows
 		strings.HasPrefix(name, "tailscale") // TODO: use --tun flag value, etc; see TODO in method doc
 }
@@ -466,16 +469,17 @@ var getPAC func() string
 // It does not set the returned State.IsExpensive. The caller can populate that.
 //
 // Deprecated: use netmon.Monitor.InterfaceState instead.
-func GetState() (*State, error) {
+func GetState(optTSInterfaceName string) (*State, error) {
 	s := &State{
 		InterfaceIPs: make(map[string][]netip.Prefix),
 		Interface:    make(map[string]Interface),
 	}
 	if err := ForeachInterface(func(ni Interface, pfxs []netip.Prefix) {
+		isTS := optTSInterfaceName != "" && ni.Name == optTSInterfaceName
 		ifUp := ni.IsUp()
 		s.Interface[ni.Name] = ni
 		s.InterfaceIPs[ni.Name] = append(s.InterfaceIPs[ni.Name], pfxs...)
-		if !ifUp || isTailscaleInterface(ni.Name, pfxs) {
+		if !ifUp || isTS || isTailscaleInterface(ni.Name, pfxs) {
 			return
 		}
 		for _, pfx := range pfxs {

net/tsdial/tsdial.go

@@ -242,7 +242,7 @@ func changeAffectsConn(delta *netmon.ChangeDelta, conn net.Conn) bool {
 	// In a few cases, we don't have a new DefaultRouteInterface (e.g. on
 	// Android; see tailscale/corp#19124); if so, pessimistically assume
 	// that all connections are affected.
-	if delta.New.DefaultRouteInterface == "" {
+	if delta.New.DefaultRouteInterface == "" && runtime.GOOS != "plan9" {
 		return true
 	}