cmd/derper: add a basic DERP server

Mostly Crawshaw's earlier code, refactored a bit.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
pull/80/head
Brad Fitzpatrick 5 years ago
parent c7e2fcd517
commit b72e6446e2

@ -0,0 +1,141 @@
// 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.
// The derper binary is a simple DERP server.
package main // import "tailscale.com/cmd/derper"
import (
"encoding/json"
"flag"
"io"
"io/ioutil"
"log"
"net"
"net/http"
"os"
"path/filepath"
"github.com/tailscale/wireguard-go/wgcfg"
"golang.org/x/crypto/acme/autocert"
"tailscale.com/atomicfile"
"tailscale.com/derp"
"tailscale.com/derp/derphttp"
"tailscale.com/types/key"
)
var (
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")
)
func defaultCertDir() string {
cacheDir, err := os.UserCacheDir()
if err == nil {
return filepath.Join(cacheDir, "tailscale", "derper-certs")
}
return ""
}
type config struct {
PrivateKey wgcfg.PrivateKey
}
func loadConfig() config {
if *configPath == "" {
log.Fatalf("derper: -c <config path> not specified")
}
b, err := ioutil.ReadFile(*configPath)
switch {
case os.IsNotExist(err):
return writeNewConfig()
case err != nil:
log.Fatal(err)
panic("unreachable")
default:
var cfg config
if err := json.Unmarshal(b, &cfg); err != nil {
log.Fatalf("derper: config: %v", err)
}
return cfg
}
}
func writeNewConfig() config {
key, err := wgcfg.NewPrivateKey()
if err != nil {
log.Fatal(err)
}
if err := os.MkdirAll(filepath.Dir(*configPath), 0777); err != nil {
log.Fatal(err)
}
cfg := config{
PrivateKey: key,
}
b, err := json.MarshalIndent(cfg, "", "\t")
if err != nil {
log.Fatal(err)
}
if err := atomicfile.WriteFile(*configPath, b, 0666); err != nil {
log.Fatal(err)
}
return cfg
}
func main() {
flag.Parse()
cfg := loadConfig()
letsEncrypt := false
if _, port, _ := net.SplitHostPort(*addr); port == "443" {
letsEncrypt = true
}
s := derp.NewServer(key.Private(cfg.PrivateKey), log.Printf)
mux := http.NewServeMux()
mux.Handle("/derp", derphttp.Handler(s))
mux.Handle("/", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain")
w.WriteHeader(200)
io.WriteString(w, "Tailscale DERP server.")
}))
httpsrv := &http.Server{
Addr: *addr,
Handler: mux,
}
var err error
if letsEncrypt {
if *certDir == "" {
log.Fatalf("missing required --certdir flag")
}
log.Printf("derper: serving on %s with TLS", *addr)
certManager := &autocert.Manager{
Prompt: autocert.AcceptTOS,
HostPolicy: autocert.HostWhitelist(*hostname),
Cache: autocert.DirCache(*certDir),
}
httpsrv.TLSConfig = certManager.TLSConfig()
go func() {
err := http.ListenAndServe(":80", certManager.HTTPHandler(nil))
if err != nil {
if err != http.ErrServerClosed {
log.Fatal(err)
}
}
}()
err = httpsrv.ListenAndServeTLS("", "")
} else {
log.Printf("derper: serving on %s", *addr)
err = httpsrv.ListenAndServe()
}
if err != nil && err != http.ErrServerClosed {
log.Fatalf("derper: %v", err)
}
}
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