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derp, cmd/derper: add debug handlers, stats

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Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2020-02-21 09:35:53 -08:00
parent 433b917977
commit 2612e54ad1
2 changed files with 160 additions and 15 deletions
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101
cmd/derper/derper.go
View File

@ -7,30 +7,37 @@
import (
"encoding/json"
"expvar"
_ "expvar"
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"net"
"net/http"
_ "net/http/pprof"
"os"
"path/filepath"
"time"
"github.com/tailscale/wireguard-go/wgcfg"
"golang.org/x/crypto/acme/autocert"
"tailscale.com/atomicfile"
"tailscale.com/derp"
"tailscale.com/derp/derphttp"
"tailscale.com/interfaces"
"tailscale.com/logpolicy"
"tailscale.com/types/key"
)
var (
dev = flag.Bool("dev", false, "run in localhost development mode")
addr = flag.String("a", ":443", "server address")
configPath = flag.String("c", "", "config file path")
certDir = flag.String("certdir", defaultCertDir(), "directory to store LetsEncrypt certs, if addr's port is :443")
hostname = flag.String("hostname", "derp.tailscale.com", "LetsEncrypt host name, if addr's port is :443")
bytesPerSec = flag.Int("mbps", 5, "Mbps (mebibit/s) per-client rate limit; 0 means unlimited")
mbps = flag.Int("mbps", 5, "Mbps (mebibit/s) per-client rate limit; 0 means unlimited")
logCollection = flag.String("logcollection", "", "If non-empty, logtail collection to log to")
)
@ -47,6 +54,9 @@ type config struct {
}
func loadConfig() config {
if *dev {
return config{PrivateKey: mustNewKey()}
}
if *configPath == "" {
log.Fatalf("derper: -c <config path> not specified")
}
@ -66,12 +76,16 @@ func loadConfig() config {
}
}
func writeNewConfig() config {
func mustNewKey() wgcfg.PrivateKey {
key, err := wgcfg.NewPrivateKey()
if err != nil {
log.Fatal(err)
}
return key
}
func writeNewConfig() config {
key := mustNewKey()
if err := os.MkdirAll(filepath.Dir(*configPath), 0777); err != nil {
log.Fatal(err)
}
@ -91,6 +105,12 @@ func writeNewConfig() config {
func main() {
flag.Parse()
if *dev {
*logCollection = ""
*addr = ":3340" // above the keys DERP
log.Printf("Running in dev mode.")
}
var logPol *logpolicy.Policy
if *logCollection != "" {
logPol = logpolicy.New(*logCollection)
@ -105,16 +125,33 @@ func main() {
}
s := derp.NewServer(key.Private(cfg.PrivateKey), log.Printf)
if *bytesPerSec != 0 {
s.BytesPerSecond = (*bytesPerSec << 20) / 8
if *mbps != 0 {
s.BytesPerSecond = (*mbps << 20) / 8
}
expvar.Publish("derp", s.ExpVar())
expvar.Publish("uptime", uptimeVar{})
// Create our own mux so we don't expose /debug/ stuff to the world.
mux := http.NewServeMux()
mux.Handle("/derp", derphttp.Handler(s))
mux.Handle("/debug/", protected(debugHandler(s)))
mux.Handle("/debug/pprof/", protected(http.DefaultServeMux)) // to net/http/pprof
mux.Handle("/debug/vars", protected(http.DefaultServeMux)) // to expvar
mux.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain")
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(200)
io.WriteString(w, "Tailscale DERP server.")
io.WriteString(w, `<html><body>
<h1>DERP</h1>
<p>
This is a
<a href="https://tailscale.com/">Tailscale</a>
<a href="https://godoc.org/tailscale.com/derp">DERP</a>
server.
</p>
`)
if allowDebugAccess(r) {
io.WriteString(w, "<p>Debug info at <a href='/debug/'>/debug/</a>.</p>\n")
}
}))
httpsrv := &http.Server{
@ -151,3 +188,55 @@ func main() {
log.Fatalf("derper: %v", err)
}
}
func protected(h http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if !allowDebugAccess(r) {
http.Error(w, "debug access denied", http.StatusForbidden)
return
}
h.ServeHTTP(w, r)
})
}
func allowDebugAccess(r *http.Request) bool {
if r.Header.Get("X-Forwarded-For") != "" {
// TODO if/when needed. For now, conservative:
return false
}
ipStr, _, err := net.SplitHostPort(r.RemoteAddr)
if err != nil {
return false
}
ip := net.ParseIP(ipStr)
return interfaces.IsTailscaleIP(ip) || ip.IsLoopback() || ipStr == os.Getenv("ALLOW_DEBUG_IP")
}
func debugHandler(s *derp.Server) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
f := func(format string, args ...interface{}) { fmt.Fprintf(w, format, args...) }
f(`<html><body>
<h1>DERP debug</h1>
<ul>
`)
f("<li><b>Hostname:</b> %v</li>\n", *hostname)
f("<li><b>Rate Limit:</b> %v Mbps</li>\n", *mbps)
f("<li><b>Uptime:</b> %v</li>\n", uptime().Round(time.Second))
f(`<li><a href="/debug/vars">/debug/vars</a></li>
<li><a href="/debug/pprof/">/debug/pprof/</a></li>
<li><a href="/debug/pprof/goroutine?debug=1">/debug/pprof/goroutine</a> (collapsed)</li>
<li><a href="/debug/pprof/goroutine?debug=2">/debug/pprof/goroutine</a> (full)</li>
<ul>
</html>
`)
})
}
var timeStart = time.Now()
func uptime() time.Duration { return time.Since(timeStart) }
type uptimeVar struct{}
func (uptimeVar) String() string { return fmt.Sprint(int64(uptime().Seconds())) }

74
derp/derp_server.go
View File

@ -13,11 +13,13 @@
crand "crypto/rand"
"encoding/json"
"errors"
"expvar"
"fmt"
"io"
"math/big"
"net"
"sync"
"sync/atomic"
"time"
"golang.org/x/crypto/nacl/box"
@ -36,21 +38,28 @@ type Server struct {
publicKey key.Public
logf logger.Logf
mu sync.Mutex
closed bool
netConns map[net.Conn]chan struct{} // chan is closed when conn closes
clients map[key.Public]*sclient
// Counters:
packetsSent int64
bytesSent int64
mu sync.Mutex
closed bool
accepts int64
netConns map[net.Conn]chan struct{} // chan is closed when conn closes
clients map[key.Public]*sclient
clientsEver map[key.Public]bool // never deleted from, for stats; fine for now
}
// NewServer returns a new DERP server. It doesn't listen on its own.
// Connections are given to it via Server.Accept.
func NewServer(privateKey key.Private, logf logger.Logf) *Server {
s := &Server{
privateKey: privateKey,
publicKey: privateKey.Public(),
logf: logf,
clients: make(map[key.Public]*sclient),
netConns: make(map[net.Conn]chan struct{}),
privateKey: privateKey,
publicKey: privateKey.Public(),
logf: logf,
clients: make(map[key.Public]*sclient),
clientsEver: make(map[key.Public]bool),
netConns: make(map[net.Conn]chan struct{}),
}
return s
}
@ -95,6 +104,7 @@ func (s *Server) Accept(nc net.Conn, brw *bufio.ReadWriter) {
closed := make(chan struct{})
s.mu.Lock()
s.accepts++
s.netConns[nc] = closed
s.mu.Unlock()
@ -125,6 +135,7 @@ func (s *Server) registerClient(c *sclient) {
s.logf("derp: %s: client %x: adding connection, replacing %s", c.nc.RemoteAddr(), c.key, old.nc.RemoteAddr())
}
s.clients[c.key] = c
s.clientsEver[c.key] = true
}
// unregisterClient removes a client from the server.
@ -311,6 +322,8 @@ func (s *Server) recvClientKey(br *bufio.Reader) (clientKey key.Public, info *sc
}
func (s *Server) sendPacket(bw *bufio.Writer, srcKey key.Public, contents []byte) error {
atomic.AddInt64(&s.packetsSent, 1)
atomic.AddInt64(&s.bytesSent, int64(len(contents)))
if err := writeFrameHeader(bw, frameRecvPacket, uint32(len(contents))); err != nil {
return err
}
@ -397,3 +410,46 @@ type sclientInfo struct {
type serverInfo struct {
}
// Stats returns stats about the server.
func (s *Server) Stats() *ServerStats {
s.mu.Lock()
defer s.mu.Unlock()
return &ServerStats{
BytesPerSecondLimit: s.BytesPerSecond,
CurrentConnections: len(s.netConns),
UniqueClientsEver: len(s.clientsEver),
TotalAccepts: s.accepts,
PacketsSent: atomic.LoadInt64(&s.packetsSent),
BytesSent: atomic.LoadInt64(&s.bytesSent),
}
}
// ExpVar returns an expvar variable suitable for registering with expvar.Publish.
func (s *Server) ExpVar() expvar.Var {
return expVar{s}
}
type expVar struct{ *Server }
// String implements the expvar.Var interface, returning the current server stats as JSON.
func (v expVar) String() string {
ss := v.Server.Stats()
j, err := json.MarshalIndent(ss, "", "\t")
if err != nil {
return "{}"
}
return string(j)
}
// ServerStats are returned by Server.Stats.
//
// It is JSON-ified by expVar for the expvar package.
type ServerStats struct {
BytesPerSecondLimit int `json:"bytesPerSecondLimit"`
CurrentConnections int `json:"currentClients"`
UniqueClientsEver int `json:"uniqueClientsEver"`
TotalAccepts int64 `json:"totalAccepts"`
PacketsSent int64 `json:"packetsSent"`
BytesSent int64 `json:"bytesSent"`
}