Merge branch 'master' of github.com:tailscale/tailscale into HEAD

2024-11-29 04:55:31 +00:00 · 2020-02-13 10:12:06 -05:00 · 2020-02-13 10:12:06 -05:00 · cbfef0c8b7
commit cbfef0c8b7
parent 2b947b3b40 e5481f33d3
20 changed files with 557 additions and 42 deletions
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@ -28,7 +28,22 @@ jobs:
    - name: Basic build
      run: go build ./cmd/...

-    - name: Test build
+    - name: macOS build
+      env:
+        GOOS: darwin
+        GOARCH: amd64
+      run: go build ./cmd/...
+
+    - name: Windows build
+      env:
+        GOOS: windows
+        GOARCH: amd64
+      run: go build ./cmd/...
+
+    - name: Cross-compile tests for other geese
+      run: ./test.sh
+
+    - name: Run tests on linux
      run: go test ./...

    - uses: k0kubun/action-slack@v2.0.0
@ -45,3 +60,4 @@ jobs:
      env:
        SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
      if: failure() && github.event_name == 'push'
+
--- a/cmd/tailscaled/ipnd.go
+++ b/cmd/tailscaled/ipnd.go
@ -20,11 +20,14 @@
 	"tailscale.com/ipn/ipnserver"
 	"tailscale.com/logpolicy"
 	"tailscale.com/wgengine"
+	"tailscale.com/wgengine/magicsock"
 )

 func main() {
 	fake := getopt.BoolLong("fake", 0, "fake tunnel+routing instead of tuntap")
 	debug := getopt.StringLong("debug", 0, "", "Address of debug server")
+	tunname := getopt.StringLong("tun", 0, "ts0", "tunnel interface name")
+	listenport := getopt.Uint16Long("port", 'p', magicsock.DefaultPort, "WireGuard port (0=autoselect)")

 	logf := wgengine.RusagePrefixLog(log.Printf)

@ -47,7 +50,7 @@ func main() {
 	if *fake {
 		e, err = wgengine.NewFakeUserspaceEngine(logf, 0, false)
 	} else {
-		e, err = wgengine.NewUserspaceEngine(logf, "ts0", 0, false)
+		e, err = wgengine.NewUserspaceEngine(logf, *tunname, *listenport, false)
 	}
 	if err != nil {
 		log.Fatalf("wgengine.New: %v\n", err)
--- a/cmd/tsshd/tsshd.go
+++ b/cmd/tsshd/tsshd.go
@ -0,0 +1,205 @@
+// 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.
+
+// +build !windows
+
+// The tsshd binary is an SSH server that accepts connections
+// from anybody on the same Tailscale network.
+//
+// It does not use passwords or SSH public key.
+//
+// Any user name is accepted; users are logged in as whoever is
+// running this daemon.
+//
+// Warning: use at your own risk. This code has had very few eyeballs
+// on it.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"time"
+	"unsafe"
+
+	"github.com/gliderlabs/ssh"
+	"github.com/kr/pty"
+	gossh "golang.org/x/crypto/ssh"
+)
+
+var (
+	port    = flag.Int("port", 2200, "port to listen on")
+	hostKey = flag.String("hostkey", "", "SSH host key")
+)
+
+func main() {
+	flag.Parse()
+	if *hostKey == "" {
+		log.Fatalf("missing required --hostkey")
+	}
+	hostKey, err := ioutil.ReadFile(*hostKey)
+	if err != nil {
+		log.Fatal(err)
+	}
+	signer, err := gossh.ParsePrivateKey(hostKey)
+	if err != nil {
+		log.Printf("failed to parse SSH host key: %v", err)
+		return
+	}
+
+	warned := false
+	for {
+		addr, iface, err := tailscaleInterface()
+		if err != nil {
+			log.Fatalf("listing interfaces: %v", err)
+		}
+		if addr == nil {
+			if !warned {
+				log.Printf("no tailscale interface found; polling until one is available")
+				warned = true
+			}
+			// TODO: use netlink or other OS-specific mechanism to efficiently
+			// wait for change in interfaces. Polling every N seconds is good enough
+			// for now.
+			time.Sleep(5 * time.Second)
+			continue
+		}
+		warned = false
+		listen := net.JoinHostPort(addr.String(), fmt.Sprint(*port))
+		log.Printf("tailscale ssh server listening on %v, %v", iface.Name, listen)
+		s := &ssh.Server{
+			Addr:    listen,
+			Handler: handleSSH,
+		}
+		s.AddHostKey(signer)
+
+		err = s.ListenAndServe()
+		log.Fatalf("tailscale sshd failed: %v", err)
+	}
+
+}
+
+// tailscaleInterface returns an err on a fatal problem, and all zero values
+// if no suitable inteface is found.
+func tailscaleInterface() (net.IP, *net.Interface, error) {
+	ifs, err := net.Interfaces()
+	if err != nil {
+		return nil, nil, err
+	}
+	for _, iface := range ifs {
+		if !maybeTailscaleInterfaceName(iface.Name) {
+			continue
+		}
+		addrs, err := iface.Addrs()
+		if err != nil {
+			continue
+		}
+		for _, a := range addrs {
+			if ipnet, ok := a.(*net.IPNet); ok && isTailscaleIP(ipnet.IP) {
+				return ipnet.IP, &iface, nil
+			}
+		}
+	}
+	return nil, nil, nil
+}
+
+// maybeTailscaleInterfaceName reports whether s is an interface
+// name that might be used by Tailscale.
+func maybeTailscaleInterfaceName(s string) bool {
+	return strings.HasPrefix(s, "wg") ||
+		strings.HasPrefix(s, "ts") ||
+		strings.HasPrefix(s, "tailscale")
+}
+
+func isTailscaleIP(ip net.IP) bool {
+	return cgNAT.Contains(ip)
+}
+
+var cgNAT = func() *net.IPNet {
+	_, ipNet, err := net.ParseCIDR("100.64.0.0/10")
+	if err != nil {
+		panic(err)
+	}
+	return ipNet
+}()
+
+func handleSSH(s ssh.Session) {
+	user := s.User()
+	addr := s.RemoteAddr()
+	ta, ok := addr.(*net.TCPAddr)
+	if !ok {
+		log.Printf("tsshd: rejecting non-TCP addr %T %v", addr, addr)
+		s.Exit(1)
+		return
+	}
+	if !isTailscaleIP(ta.IP) {
+		log.Printf("tsshd: rejecting non-Tailscale addr %v", ta.IP)
+		s.Exit(1)
+		return
+	}
+
+	log.Printf("new session for %q from %v", user, ta)
+	defer log.Printf("closing session for %q from %v", user, ta)
+	ptyReq, winCh, isPty := s.Pty()
+	if !isPty {
+		fmt.Fprintf(s, "TODO scp etc")
+		s.Exit(1)
+		return
+	}
+
+	userWantsShell := len(s.Command()) == 0
+
+	if userWantsShell {
+		shell, err := shellOfUser(s.User())
+		if err != nil {
+			fmt.Fprintf(s, "failed to find shell: %v\n", err)
+			s.Exit(1)
+			return
+		}
+		cmd := exec.Command(shell)
+		cmd.Env = append(cmd.Env, fmt.Sprintf("TERM=%s", ptyReq.Term))
+		f, err := pty.Start(cmd)
+		if err != nil {
+			log.Printf("running shell: %v", err)
+			s.Exit(1)
+			return
+		}
+		defer f.Close()
+		go func() {
+			for win := range winCh {
+				setWinsize(f, win.Width, win.Height)
+			}
+		}()
+		go func() {
+			io.Copy(f, s) // stdin
+		}()
+		io.Copy(s, f) // stdout
+		cmd.Process.Kill()
+		if err := cmd.Wait(); err != nil {
+			s.Exit(1)
+		}
+		s.Exit(0)
+		return
+	}
+
+	fmt.Fprintf(s, "TODO: args\n")
+	s.Exit(1)
+}
+
+func shellOfUser(user string) (string, error) {
+	// TODO
+	return "/bin/bash", nil
+}
+
+func setWinsize(f *os.File, w, h int) {
+	syscall.Syscall(syscall.SYS_IOCTL, f.Fd(), uintptr(syscall.TIOCSWINSZ),
+		uintptr(unsafe.Pointer(&struct{ h, w, x, y uint16 }{uint16(h), uint16(w), 0, 0})))
+}
--- a/go.mod
+++ b/go.mod
@ -3,18 +3,23 @@ module tailscale.com
 go 1.13

 require (
+	github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239 // indirect
 	github.com/apenwarr/fixconsole v0.0.0-20191012055117-5a9f6489cc29
+	github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568 // indirect
+	github.com/gliderlabs/ssh v0.2.2
 	github.com/go-ole/go-ole v1.2.4
 	github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e
 	github.com/google/go-cmp v0.4.0
 	github.com/klauspost/compress v1.9.8
+	github.com/kr/pty v1.1.1
 	github.com/mdlayher/netlink v1.1.0
 	github.com/pborman/getopt v0.0.0-20190409184431-ee0cd42419d3
 	github.com/tailscale/hujson v0.0.0-20190930033718-5098e564d9b3
+	github.com/tailscale/winipcfg-go v0.0.0-20200213045944-185b07f8233f
 	github.com/tailscale/wireguard-go v0.0.0-20200211020303-f39bc8eeee1b
 	golang.org/x/crypto v0.0.0-20200210222208-86ce3cb69678
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
-	golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5
+	golang.org/x/sys v0.0.0-20200212091648-12a6c2dcc1e4
 	gortc.io/stun v1.22.1
 	honnef.co/go/tools v0.0.1-2019.2.3 // indirect
 )
--- a/go.sum
+++ b/go.sum
@ -1,10 +1,16 @@
 cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
 github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239 h1:kFOfPq6dUM1hTo4JG6LR5AXSUEsOjtdm0kw0FtQtMJA=
+github.com/anmitsu/go-shlex v0.0.0-20161002113705-648efa622239/go.mod h1:2FmKhYUyUczH0OGQWaF5ceTx0UBShxjsH6f8oGKYe2c=
 github.com/apenwarr/fixconsole v0.0.0-20191012055117-5a9f6489cc29 h1:muXWUcay7DDy1/hEQWrYlBy+g0EuwT70sBHg65SeUc4=
 github.com/apenwarr/fixconsole v0.0.0-20191012055117-5a9f6489cc29/go.mod h1:JYWahgHer+Z2xbsgHPtaDYVWzeHDminu+YIBWkxpCAY=
 github.com/apenwarr/w32 v0.0.0-20190407065021-aa00fece76ab h1:CMGzRRCjnD50RjUFSArBLuCxiDvdp7b8YPAcikBEQ+k=
 github.com/apenwarr/w32 v0.0.0-20190407065021-aa00fece76ab/go.mod h1:nfFtvHn2Hgs9G1u0/J6LHQv//EksNC+7G8vXmd1VTJ8=
+github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568 h1:BHsljHzVlRcyQhjrss6TZTdY2VfCqZPbv5k3iBFa2ZQ=
+github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568/go.mod h1:xEzjJPgXI435gkrCt3MPfRiAkVrwSbHsst4LCFVfpJc=
+github.com/gliderlabs/ssh v0.2.2 h1:6zsha5zo/TWhRhwqCD3+EarCAgZ2yN28ipRnGPnwkI0=
+github.com/gliderlabs/ssh v0.2.2/go.mod h1:U7qILu1NlMHj9FlMhZLlkCdDnU1DBEAqr0aevW3Awn0=
 github.com/go-ole/go-ole v1.2.4 h1:nNBDSCOigTSiarFpYE9J/KtEA1IOW4CNeqT9TQDqCxI=
 github.com/go-ole/go-ole v1.2.4/go.mod h1:XCwSNxSkXRo4vlyPy93sltvi/qJq0jqQhjqQNIwKuxM=
 github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e h1:1r7pUrabqp18hOBcwBwiTsbnFeTZHV9eER/QT5JVZxY=
@ -23,6 +29,7 @@ github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+o
 github.com/klauspost/compress v1.9.8 h1:VMAMUUOh+gaxKTMk+zqbjsSjsIcUcL/LF4o63i82QyA=
 github.com/klauspost/compress v1.9.8/go.mod h1:RyIbtBH6LamlWaDj8nUwkbUhJ87Yi3uG0guNDohfE1A=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1 h1:VkoXIwSboBpnk99O/KFauAEILuNHv5DVFKZMBN/gUgw=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/mdlayher/netlink v0.0.0-20190409211403-11939a169225/go.mod h1:eQB3mZE4aiYnlUsyGGCOpPETfdQq4Jhsgf1fk3cwQaA=
@ -34,6 +41,8 @@ github.com/pborman/getopt v0.0.0-20190409184431-ee0cd42419d3/go.mod h1:85jBQOZwp
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/tailscale/hujson v0.0.0-20190930033718-5098e564d9b3 h1:rdtXEo9yffOjh4vZQJw3heaY+ggXKp+zvMX5fihh6lI=
 github.com/tailscale/hujson v0.0.0-20190930033718-5098e564d9b3/go.mod h1:STqf+YV0ADdzk4ejtXFsGqDpATP9JoL0OB+hiFQbkdE=
+github.com/tailscale/winipcfg-go v0.0.0-20200213045944-185b07f8233f h1:q2ynfOHxHaaMnkZ1YHswWeO6wEk7IyOnkFozytZ1ztc=
+github.com/tailscale/winipcfg-go v0.0.0-20200213045944-185b07f8233f/go.mod h1:x880GWw5fvrl2DVTQ04ttXQD4DuppTt1Yz6wLibbjNE=
 github.com/tailscale/wireguard-go v0.0.0-20191108062213-b93cdd0582db h1:oP0crfwOb3WZSVrMVm/o51NXN2JirDlcdlNEIPTmgI0=
 github.com/tailscale/wireguard-go v0.0.0-20200207221558-a158079b156a h1:5TWA3nl2QUfL9OiE3tlBpqJd4GYd4hbGtDNkWQQ2fyc=
 github.com/tailscale/wireguard-go v0.0.0-20200207221558-a158079b156a/go.mod h1:QPS8HjBzzAXoQNndUNx2efJaQbCCz8nI2Cv1ksTUHyY=
@ -66,8 +75,10 @@ golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d h1:TzXSXBo42m9gQenoE3b9BG
 golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4 h1:YUO/7uOKsKeq9UokNS62b8FYywz3ker1l1vDZRCRefw=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190310054646-10058d7d4faa/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190405154228-4b34438f7a67/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190411185658-b44545bcd369/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@ -77,6 +88,8 @@ golang.org/x/sys v0.0.0-20191003212358-c178f38b412c/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5 h1:LfCXLvNmTYH9kEmVgqbnsWfruoXZIrh4YBgqVHtDvw0=
 golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200212091648-12a6c2dcc1e4 h1:sfkvUWPNGwSV+8/fNqctR5lS2AqCSqYwXdrjCxp/dXo=
+golang.org/x/sys v0.0.0-20200212091648-12a6c2dcc1e4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
--- a/test.sh
+++ b/test.sh
@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+function remove_test_files {
+    rm -f ./*test{,.exe}
+}
+
+function fail {
+    printf '%s\n' "$1" >&2
+    # If we fail, clean up after ourselves
+    remove_test_files
+    exit 1
+}
+
+function main {
+    test_dirs=()
+    while IFS= read -r -d '' file
+    do
+        dir=$(dirname "$file")
+        if [[ ! " ${test_dirs[*]} " =~ ${dir} ]]; then
+            test_dirs+=("$dir")
+        fi
+    done <   <(find . -type f -iname '*_test.go' -print0)
+
+    for goos in openbsd darwin windows
+    do
+        for dir in "${test_dirs[@]}"; do
+            echo "Testing GOOS=$goos in dir $dir"
+            GOOS="$goos" go test -c "./$dir" || fail "Test failed using $goos and $dir"
+        done
+    done
+
+    # If all goes well, we should still clean up the test files
+    echo "Test complete"
+    remove_test_files
+}
+
+main "$@"
+
--- a/wgengine/faketun.go
+++ b/wgengine/faketun.go
@ -5,9 +5,10 @@
 package wgengine

 import (
-	"github.com/tailscale/wireguard-go/tun"
 	"io"
 	"os"
+
+	"github.com/tailscale/wireguard-go/tun"
 )

 type fakeTun struct {
@ -16,6 +17,9 @@ type fakeTun struct {
 	closechan chan struct{}
 }

+// NewFakeTun returns a fake TUN device that does not depend on the
+// operating system or any special permissions.
+// It primarily exists for testing.
 func NewFakeTun() tun.Device {
 	return &fakeTun{
 		datachan:  make(chan []byte),
--- a/wgengine/ifconfig_windows.go
+++ b/wgengine/ifconfig_windows.go
@ -16,13 +16,13 @@
 	"time"
 	"unsafe"

-	"github.com/go-ole/go-ole"
+	ole "github.com/go-ole/go-ole"
+	winipcfg "github.com/tailscale/winipcfg-go"
 	"github.com/tailscale/wireguard-go/device"
 	"github.com/tailscale/wireguard-go/tun"
 	"github.com/tailscale/wireguard-go/wgcfg"
 	"golang.org/x/sys/windows"
 	"golang.org/x/sys/windows/registry"
-	"golang.zx2c4.com/winipcfg"
 	"tailscale.com/wgengine/winnet"
 )

--- a/wgengine/router_darwin.go
+++ b/wgengine/router_darwin.go
@ -32,5 +32,6 @@ func (r *darwinRouter) SetRoutes(rs RouteSettings) error {
 	return nil
 }

-func (r *darwinRouter) Close() {
+func (r *darwinRouter) Close() error {
+	return nil
 }
--- a/wgengine/router_default.go
+++ b/wgengine/router_default.go
@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

-// +build !windows,!linux,!darwin
+// +build !windows,!linux,!darwin,!openbsd

 package wgengine

@ -13,5 +13,5 @@
 )

 func NewUserspaceRouter(logf logger.Logf, tunname string, dev *device.Device, tuntap tun.Device, netChanged func()) Router {
-	return NewFakeRouter(logf, tunname, dev, tuntap)
+	return NewFakeRouter(logf, tunname, dev, tuntap, netChanged)
 }
--- a/wgengine/router_fake.go
+++ b/wgengine/router_fake.go
@ -16,11 +16,10 @@ type fakeRouter struct {
 }

 func NewFakeRouter(logf logger.Logf, tunname string, dev *device.Device, tuntap tun.Device, netChanged func()) Router {
-	r := fakeRouter{
+	return &fakeRouter{
 		logf:    logf,
 		tunname: tunname,
 	}
-	return &r
 }

 func (r *fakeRouter) Up() error {
@ -33,6 +32,7 @@ func (r *fakeRouter) SetRoutes(rs RouteSettings) error {
 	return nil
 }

-func (r *fakeRouter) Close() {
+func (r *fakeRouter) Close() error {
 	r.logf("Warning: fakeRouter.Close: not implemented.\n")
+	return nil
 }
--- a/wgengine/router_linux.go
+++ b/wgengine/router_linux.go
@ -57,6 +57,8 @@ func cmd(args ...string) *exec.Cmd {
 func (r *linuxRouter) Up() error {
 	out, err := cmd("ip", "link", "set", r.tunname, "up").CombinedOutput()
 	if err != nil {
+		// TODO: this should return an error; why is it calling log.Fatalf?
+		// Audit callers to make sure they're handling errors.
 		log.Fatalf("running ip link failed: %v\n%s", err, out)
 	}

@ -154,6 +156,7 @@ func (r *linuxRouter) SetRoutes(rs RouteSettings) error {
 	r.local = rs.LocalAddr
 	r.routes = newRoutes

+	// TODO: this:
 	if false {
 		if err := r.replaceResolvConf(rs.DNS, rs.DNSDomains); err != nil {
 			errq = fmt.Errorf("replacing resolv.conf failed: %v", err)
@ -162,12 +165,17 @@ func (r *linuxRouter) SetRoutes(rs RouteSettings) error {
 	return errq
 }

-func (r *linuxRouter) Close() {
+func (r *linuxRouter) Close() error {
+	var ret error
 	r.mon.Close()
 	if err := r.restoreResolvConf(); err != nil {
 		r.logf("failed to restore system resolv.conf: %v", err)
+		if ret == nil {
+			ret = err
+		}
 	}
 	// TODO(apenwarr): clean up iptables etc.
+	return ret
 }

 const (
--- a/wgengine/router_openbsd.go
+++ b/wgengine/router_openbsd.go
@ -0,0 +1,176 @@
+// 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 wgengine
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"os/exec"
+
+	"github.com/tailscale/wireguard-go/device"
+	"github.com/tailscale/wireguard-go/tun"
+	"github.com/tailscale/wireguard-go/wgcfg"
+	"tailscale.com/logger"
+)
+
+// For now this router only supports the userspace WireGuard implementations.
+//
+// There is an experimental kernel version in the works:
+// https://git.zx2c4.com/wireguard-openbsd.
+//
+// TODO(mbaillie): netlink-style monitoring might be possible through
+// `ifstated(8)`/`devd(8)`, or become possible with the OpenBSD kernel
+// implementation. This merits further investigation.
+
+type openbsdRouter struct {
+	logf    logger.Logf
+	tunname string
+	local   wgcfg.CIDR
+	routes  map[wgcfg.CIDR]struct{}
+}
+
+func NewUserspaceRouter(logf logger.Logf, tunname string, _ *device.Device, tuntap tun.Device, _ func()) Router {
+	r := openbsdRouter{
+		logf:    logf,
+		tunname: tunname,
+	}
+	return &r
+}
+
+// TODO(mbaillie): extract as identical to linux version
+func cmd(args ...string) *exec.Cmd {
+	if len(args) == 0 {
+		log.Fatalf("exec.Cmd(%#v) invalid; need argv[0]\n", args)
+	}
+	return exec.Command(args[0], args[1:]...)
+}
+
+func (r *openbsdRouter) Up() error {
+	ifup := []string{"ifconfig", r.tunname, "up"}
+	if out, err := cmd(ifup...).CombinedOutput(); err != nil {
+		r.logf("running ifconfig failed: %v\n%s", err, out)
+		return err
+	}
+	return nil
+}
+
+func (r *openbsdRouter) SetRoutes(rs RouteSettings) error {
+	var errq error
+
+	if rs.LocalAddr != r.local {
+		if r.local != (wgcfg.CIDR{}) {
+			addrdel := []string{"ifconfig", r.tunname,
+				"inet", r.local.String(), "-alias"}
+			out, err := cmd(addrdel...).CombinedOutput()
+			if err != nil {
+				r.logf("addr del failed: %v: %v\n%s", addrdel, err, out)
+				if errq == nil {
+					errq = err
+				}
+			}
+
+			routedel := []string{"route", "-q", "-n",
+				"del", "-inet", r.local.String(),
+				"-iface", r.local.IP.String()}
+			if out, err := cmd(routedel...).CombinedOutput(); err != nil {
+				r.logf("route del failed: %v: %v\n%s", routedel, err, out)
+				if errq == nil {
+					errq = err
+				}
+			}
+		}
+
+		addradd := []string{"ifconfig", r.tunname,
+			"inet", rs.LocalAddr.String(), "alias"}
+		out, err := cmd(addradd...).CombinedOutput()
+		if err != nil {
+			r.logf("addr add failed: %v: %v\n%s", addradd, err, out)
+			if errq == nil {
+				errq = err
+			}
+		}
+
+		routeadd := []string{"route", "-q", "-n",
+			"add", "-inet", rs.LocalAddr.String(),
+			"-iface", rs.LocalAddr.IP.String()}
+		if out, err := cmd(routeadd...).CombinedOutput(); err != nil {
+			r.logf("route add failed: %v: %v\n%s", routeadd, err, out)
+			if errq == nil {
+				errq = err
+			}
+		}
+	}
+
+	newRoutes := make(map[wgcfg.CIDR]struct{})
+	for _, peer := range rs.Cfg.Peers {
+		for _, route := range peer.AllowedIPs {
+			newRoutes[route] = struct{}{}
+		}
+	}
+	for route := range r.routes {
+		if _, keep := newRoutes[route]; !keep {
+			net := route.IPNet()
+			nip := net.IP.Mask(net.Mask)
+			nstr := fmt.Sprintf("%v/%d", nip, route.Mask)
+			routedel := []string{"route", "-q", "-n",
+				"del", "-inet", nstr,
+				"-iface", rs.LocalAddr.IP.String()}
+			out, err := cmd(routedel...).CombinedOutput()
+			if err != nil {
+				r.logf("route del failed: %v: %v\n%s", routedel, err, out)
+				if errq == nil {
+					errq = err
+				}
+			}
+		}
+	}
+	for route := range newRoutes {
+		if _, exists := r.routes[route]; !exists {
+			net := route.IPNet()
+			nip := net.IP.Mask(net.Mask)
+			nstr := fmt.Sprintf("%v/%d", nip, route.Mask)
+			routeadd := []string{"route", "-q", "-n",
+				"add", "-inet", nstr,
+				"-iface", rs.LocalAddr.IP.String()}
+			out, err := cmd(routeadd...).CombinedOutput()
+			if err != nil {
+				r.logf("addr add failed: %v: %v\n%s", routeadd, err, out)
+				if errq == nil {
+					errq = err
+				}
+			}
+		}
+	}
+
+	r.local = rs.LocalAddr
+	r.routes = newRoutes
+
+	if err := r.replaceResolvConf(rs.DNS, rs.DNSDomains); err != nil {
+		errq = fmt.Errorf("replacing resolv.conf failed: %v", err)
+	}
+
+	return errq
+}
+
+func (r *openbsdRouter) Close() error {
+	out, err := cmd("ifconfig", r.tunname, "down").CombinedOutput()
+	if err != nil {
+		r.logf("running ifconfig failed: %v\n%s", err, out)
+	}
+
+	if err := r.restoreResolvConf(); err != nil {
+		r.logf("failed to restore system resolv.conf: %v", err)
+	}
+
+	// TODO(mbaillie): wipe routes
+
+	return nil
+}
+
+// TODO(mbaillie): these are no-ops for now. They could re-use the Linux funcs
+// (sans systemd parts), but I note Linux DNS is disabled(?) so leaving for now.
+func (r *openbsdRouter) replaceResolvConf(_ []net.IP, _ []string) error { return nil }
+func (r *openbsdRouter) restoreResolvConf() error                       { return nil }
--- a/wgengine/router_windows.go
+++ b/wgengine/router_windows.go
@ -7,9 +7,9 @@
 import (
 	"log"

+	winipcfg "github.com/tailscale/winipcfg-go"
 	"github.com/tailscale/wireguard-go/device"
 	"github.com/tailscale/wireguard-go/tun"
-	"golang.zx2c4.com/winipcfg"
 	"tailscale.com/logger"
 )

@ -43,7 +43,7 @@ func (r *winRouter) Up() error {
 }

 func (r *winRouter) SetRoutes(rs RouteSettings) error {
-	err := ConfigureInterface(&rs.Cfg, r.nativeTun, rs.DNS, rs.DNSDomains)
+	err := ConfigureInterface(rs.Cfg, r.nativeTun, rs.DNS, rs.DNSDomains)
 	if err != nil {
 		r.logf("ConfigureInterface: %v\n", err)
 		return err
@ -51,8 +51,9 @@ func (r *winRouter) SetRoutes(rs RouteSettings) error {
 	return nil
 }

-func (r *winRouter) Close() {
+func (r *winRouter) Close() error {
 	if r.routeChangeCallback != nil {
 		r.routeChangeCallback.Unregister()
 	}
+	return nil
 }
--- a/wgengine/rtnlmon/mon.go
+++ b/wgengine/rtnlmon/mon.go
@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

+// +build !windows
+
 // Package rtnlmon watches for "interesting" changes to the network
 // stack and fires a callback.
 package rtnlmon
--- a/wgengine/rusage.go
+++ b/wgengine/rusage.go
@ -11,7 +11,10 @@
 	"tailscale.com/logger"
 )

-func RusagePrefixLog(logf logger.Logf) func(f string, argv ...interface{}) {
+// RusagePrefixLog returns a Logf func wrapping the provided logf func that adds
+// a prefixed log message to each line with the current binary memory usage
+// and max RSS.
+func RusagePrefixLog(logf logger.Logf) logger.Logf {
 	return func(f string, argv ...interface{}) {
 		var m runtime.MemStats
 		runtime.ReadMemStats(&m)
--- a/wgengine/rusage_nowindows.go
+++ b/wgengine/rusage_nowindows.go
@ -23,7 +23,7 @@ func rusageMaxRSS() float64 {
 		rss /= 1 << 20 // ru_maxrss is bytes on darwin
 	} else {
 		// ru_maxrss is kilobytes elsewhere (linux, openbsd, etc)
-		rss /= 1024
+		rss /= 1 << 10
 	}
 	return rss
 }
--- a/wgengine/userspace.go
+++ b/wgengine/userspace.go
@ -67,14 +67,14 @@ func NewUserspaceEngine(logf logger.Logf, tunname string, listenPort uint16, der

 	tuntap, err := tun.CreateTUN(tunname, device.DefaultMTU)
 	if err != nil {
-		log.Printf("CreateTUN: %v\n", err)
+		logf("CreateTUN: %v\n", err)
 		return nil, err
 	}
-	log.Printf("CreateTUN ok.\n")
+	logf("CreateTUN ok.\n")

 	e, err := NewUserspaceEngineAdvanced(logf, tuntap, NewUserspaceRouter, listenPort, derp)
 	if err != nil {
-		log.Printf("NewUserspaceEngineAdv: %v\n", err)
+		logf("NewUserspaceEngineAdv: %v\n", err)
 		return nil, err
 	}
 	return e, err
@ -205,7 +205,7 @@ func (e *userspaceEngine) Reconfig(cfg *wgcfg.Config, dnsDomains []string) error
 		e.peerSequence[i] = p.PublicKey
 	}

-	// TODO(apenwarr): get rid of silly uapi stuff for in-process comms
+	// TODO(apenwarr): get rid of uapi stuff for in-process comms
 	uapi, err := cfg.ToUAPI()
 	if err != nil {
 		return err
@ -239,7 +239,7 @@ func (e *userspaceEngine) Reconfig(cfg *wgcfg.Config, dnsDomains []string) error

 	rs := RouteSettings{
 		LocalAddr:  cidr,
-		Cfg:        *cfg,
+		Cfg:        cfg,
 		DNS:        cfg.Interface.Dns,
 		DNSDomains: dnsDomains,
 	}
--- a/wgengine/watchdog.go
+++ b/wgengine/watchdog.go
@ -5,9 +5,9 @@
 package wgengine

 import (
-	"bytes"
 	"log"
 	"runtime/pprof"
+	"strings"
 	"time"

 	"github.com/tailscale/wireguard-go/wgcfg"
@ -45,7 +45,7 @@ func (e *watchdogEngine) watchdogErr(name string, fn func() error) error {
 		t.Stop()
 		return err
 	case <-t.C:
-		buf := new(bytes.Buffer)
+		buf := new(strings.Builder)
 		pprof.Lookup("goroutine").WriteTo(buf, 1)
 		e.logf("wgengine watchdog stacks:\n%s", buf.String())
 		e.fatalf("wgengine: watchdog timeout on %s", name)
--- a/wgengine/wgengine.go
+++ b/wgengine/wgengine.go
@ -14,6 +14,10 @@
 	"tailscale.com/wgengine/filter"
 )

+// ByteCount is the number of bytes that have been sent or received.
+//
+// TODO: why is this a type? remove?
+// TODO: document whether it's payload bytes only or if it includes framing overhead.
 type ByteCount int64

 type PeerStatus struct {
@ -22,20 +26,29 @@ type PeerStatus struct {
 	NodeKey          tailcfg.NodeKey
 }

+// Status is the Engine status.
 type Status struct {
 	Peers      []PeerStatus
 	LocalAddrs []string // TODO(crawshaw): []wgcfg.Endpoint?
 }

-type StatusCallback func(s *Status, err error)
+// StatusCallback is the type of status callbacks used by
+// Engine.SetStatusCallback.
+//
+// Exactly one of Status or error is non-nil.
+type StatusCallback func(*Status, error)

+// RouteSettings is the full WireGuard config data (set of peers keys,
+// IP, etc in wgcfg.Config) plus the things that WireGuard doesn't do
+// itself, like DNS stuff.
 type RouteSettings struct {
-	LocalAddr  wgcfg.CIDR
+	LocalAddr  wgcfg.CIDR // TODO: why is this here? how does it differ from wgcfg.Config's info?
 	DNS        []net.IP
 	DNSDomains []string
-	Cfg        wgcfg.Config
+	Cfg        *wgcfg.Config
 }

+// OnlyRelevantParts returns a string minimally describing the route settings.
 func (rs *RouteSettings) OnlyRelevantParts() string {
 	var peers [][]wgcfg.CIDR
 	for _, p := range rs.Cfg.Peers {
@ -45,31 +58,58 @@ func (rs *RouteSettings) OnlyRelevantParts() string {
 		rs.LocalAddr, rs.DNS, rs.DNSDomains, peers)
 }

+// Router is responsible for managing the system route table.
+//
+// There's only one instance, and one per-OS implementation.
 type Router interface {
+	// Up brings the router up.
 	Up() error
-	SetRoutes(rs RouteSettings) error
-	Close()
+
+	// SetRoutes is called regularly on network map updates.
+	// It's how you kernel route table entries are populated for
+	// each peer.
+	SetRoutes(RouteSettings) error
+
+	// Close closes the router.
+	Close() error
 }

+// Engine is the Tailscale WireGuard engine interface.
 type Engine interface {
-	// Reconfigure wireguard and make sure it's running.
+	// Reconfig reconfigures WireGuard and makes sure it's running.
 	// This also handles setting up any kernel routes.
+	//
+	// The provided DNS domains are not part of wgcfg.Config, as
+	// WireGuard itself doesn't care about such things.
+	//
+	// This is called whenever the tailcontrol (control plane)
+	// sends an updated network map.
 	Reconfig(cfg *wgcfg.Config, dnsDomains []string) error
-	// Update the packet filter.
-	SetFilter(filt *filter.Filter)
-	// Set the function to call when wireguard status changes.
-	SetStatusCallback(cb StatusCallback)
-	// Request a wireguard status update right away, sent to the callback.
+
+	// SetFilter updates the packet filter.
+	SetFilter(*filter.Filter)
+
+	// SetStatusCallback sets the function to call when the
+	// WireGuard status changes.
+	SetStatusCallback(StatusCallback)
+
+	// RequestStatus requests a WireGuard status update right
+	// away, sent to the callback registered via SetStatusCallback.
 	RequestStatus()
-	// Shut down this wireguard instance, remove any routes it added, etc.
-	// To bring it up again later, you'll need a new Engine.
+
+	// Close shuts down this wireguard instance, remove any routes
+	// it added, etc. To bring it up again later, you'll need a
+	// new Engine.
 	Close()
-	// Wait until the Engine is .Close()ed or aborts with an error.
-	// You don't have to call this.
+
+	// Wait waits until the Engine's Close method is called or the
+	// engine aborts with an error. You don't have to call this.
+	// TODO: return an error?
 	Wait()
+
 	// LinkChange informs the engine that the system network
 	// link has changed. The isExpensive parameter is set on links
-	// where sending packets uses substantial power or dollars
-	// (such as LTE on a phone).
+	// where sending packets uses substantial power or money,
+	// such as mobile data on a phone.
 	LinkChange(isExpensive bool)
 }