// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package interfaces import ( "errors" "net/netip" "os/exec" "testing" "go4.org/mem" "tailscale.com/util/lineread" "tailscale.com/version" ) func TestLikelyHomeRouterIPSyscallExec(t *testing.T) { syscallIP, syscallOK := likelyHomeRouterIPBSDFetchRIB() netstatIP, netstatIf, netstatOK := likelyHomeRouterIPDarwinExec() if syscallOK != netstatOK || syscallIP != netstatIP { t.Errorf("syscall() = %v, %v, netstat = %v, %v", syscallIP, syscallOK, netstatIP, netstatOK, ) } if !syscallOK { return } def, err := defaultRoute() if err != nil { t.Errorf("defaultRoute() error: %v", err) } if def.InterfaceName != netstatIf { t.Errorf("syscall default route interface %s differs from netstat %s", def.InterfaceName, netstatIf) } } /* Parse out 10.0.0.1 and en0 from: $ netstat -r -n -f inet Routing tables Internet: Destination Gateway Flags Netif Expire default 10.0.0.1 UGSc en0 default link#14 UCSI utun2 10/16 link#4 UCS en0 ! 10.0.0.1/32 link#4 UCS en0 ! ... */ func likelyHomeRouterIPDarwinExec() (ret netip.Addr, netif string, ok bool) { if version.IsMobile() { // Don't try to do subprocesses on iOS. Ends up with log spam like: // kernel: "Sandbox: IPNExtension(86580) deny(1) process-fork" // This is why we have likelyHomeRouterIPDarwinSyscall. return ret, "", false } cmd := exec.Command("/usr/sbin/netstat", "-r", "-n", "-f", "inet") stdout, err := cmd.StdoutPipe() if err != nil { return } if err := cmd.Start(); err != nil { return } defer cmd.Wait() var f []mem.RO lineread.Reader(stdout, func(lineb []byte) error { line := mem.B(lineb) if !mem.Contains(line, mem.S("default")) { return nil } f = mem.AppendFields(f[:0], line) if len(f) < 4 || !f[0].EqualString("default") { return nil } ipm, flagsm, netifm := f[1], f[2], f[3] if !mem.Contains(flagsm, mem.S("G")) { return nil } if mem.Contains(flagsm, mem.S("I")) { return nil } ip, err := netip.ParseAddr(string(mem.Append(nil, ipm))) if err == nil && ip.IsPrivate() { ret = ip netif = netifm.StringCopy() // We've found what we're looking for. return errStopReadingNetstatTable } return nil }) return ret, netif, ret.IsValid() } func TestFetchRoutingTable(t *testing.T) { // Issue 1345: this used to be flaky on darwin. for i := 0; i < 20; i++ { _, err := fetchRoutingTable() if err != nil { t.Fatal(err) } } } var errStopReadingNetstatTable = errors.New("found private gateway")