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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
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@@ -7,30 +7,37 @@ package main // import "tailscale.com/cmd/derper"
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())) }