mirror of
https://github.com/tailscale/tailscale.git
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7f97cf654d
This makes it easier to run microproxy locally during development. Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
190 lines
5.3 KiB
Go
190 lines
5.3 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// microproxy proxies incoming HTTPS connections to another
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// destination. Instead of managing its own TLS certificates, it
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// borrows issued certificates and keys from an autocert directory.
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package main
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import (
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"crypto/tls"
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"encoding/json"
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"flag"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"net/http"
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"net/http/httputil"
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"net/url"
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"path/filepath"
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"strings"
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"sync"
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"time"
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"tailscale.com/logpolicy"
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"tailscale.com/tsweb"
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)
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var (
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addr = flag.String("addr", ":4430", "server address")
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certdir = flag.String("certdir", "", "directory to borrow LetsEncrypt certificates from")
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hostname = flag.String("hostname", "", "hostname to serve")
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logCollection = flag.String("logcollection", "", "If non-empty, logtail collection to log to")
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nodeExporter = flag.String("node-exporter", "http://localhost:9100", "URL of the local prometheus node exporter")
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goVarsURL = flag.String("go-vars-url", "http://localhost:8383/debug/vars", "URL of a local Go server's /debug/vars endpoint")
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insecure = flag.Bool("insecure", false, "serve over http, for development")
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)
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func main() {
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flag.Parse()
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if *logCollection != "" {
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logpolicy.New(*logCollection)
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}
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ne, err := url.Parse(*nodeExporter)
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if err != nil {
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log.Fatalf("Couldn't parse URL %q: %v", *nodeExporter, err)
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}
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proxy := httputil.NewSingleHostReverseProxy(ne)
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proxy.FlushInterval = time.Second
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if _, err = url.Parse(*goVarsURL); err != nil {
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log.Fatalf("Couldn't parse URL %q: %v", *goVarsURL, err)
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}
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mux := tsweb.NewMux(http.HandlerFunc(debugHandler))
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mux.Handle("/metrics", tsweb.Protected(proxy))
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mux.Handle("/varz", tsweb.Protected(tsweb.StdHandler(&goVarsHandler{*goVarsURL}, log.Printf)))
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ch := &certHolder{
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hostname: *hostname,
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path: filepath.Join(*certdir, *hostname),
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}
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httpsrv := &http.Server{
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Addr: *addr,
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Handler: mux,
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}
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if !*insecure {
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httpsrv.TLSConfig = &tls.Config{GetCertificate: ch.GetCertificate}
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err = httpsrv.ListenAndServeTLS("", "")
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} else {
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err = httpsrv.ListenAndServe()
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}
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if err != nil && err != http.ErrServerClosed {
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log.Fatal(err)
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}
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}
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type goVarsHandler struct {
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url string
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}
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func promPrint(w io.Writer, prefix string, obj map[string]interface{}) {
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for k, i := range obj {
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if prefix != "" {
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k = prefix + "_" + k
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}
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switch v := i.(type) {
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case map[string]interface{}:
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promPrint(w, k, v)
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case float64:
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const saveConfigReject = "control_save_config_rejected_"
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const saveConfig = "control_save_config_"
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switch {
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case strings.HasPrefix(k, saveConfigReject):
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fmt.Fprintf(w, "control_save_config_rejected{reason=%q} %f\n", k[len(saveConfigReject):], v)
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case strings.HasPrefix(k, saveConfig):
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fmt.Fprintf(w, "control_save_config{reason=%q} %f\n", k[len(saveConfig):], v)
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default:
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fmt.Fprintf(w, "%s %f\n", k, v)
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}
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default:
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fmt.Fprintf(w, "# Skipping key %q, unhandled type %T\n", k, v)
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}
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}
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}
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func (h *goVarsHandler) ServeHTTPReturn(w http.ResponseWriter, r *http.Request) error {
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resp, err := http.Get(h.url)
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if err != nil {
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return tsweb.Error(http.StatusInternalServerError, "fetch failed", err)
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}
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defer resp.Body.Close()
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var mon map[string]interface{}
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if err := json.NewDecoder(resp.Body).Decode(&mon); err != nil {
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return tsweb.Error(http.StatusInternalServerError, "fetch failed", err)
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}
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w.WriteHeader(http.StatusOK)
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promPrint(w, "", mon)
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return nil
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}
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// certHolder loads and caches a TLS certificate from disk, reloading
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// it every hour.
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type certHolder struct {
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hostname string // only hostname allowed in SNI
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path string // path of certificate+key combined PEM file
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mu sync.Mutex
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cert *tls.Certificate // cached parsed cert+key
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loaded time.Time
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}
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func (c *certHolder) GetCertificate(ch *tls.ClientHelloInfo) (*tls.Certificate, error) {
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if ch.ServerName != c.hostname {
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return nil, fmt.Errorf("wrong client SNI %q", ch.ServerName)
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}
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c.mu.Lock()
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defer c.mu.Unlock()
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if time.Since(c.loaded) > time.Hour {
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if err := c.loadLocked(); err != nil {
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log.Printf("Reloading cert %q: %v", c.path, err)
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// continue anyway, we might be able to serve off the stale cert.
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}
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}
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return c.cert, nil
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}
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// load reloads the TLS certificate and key from disk. Caller must
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// hold mu.
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func (c *certHolder) loadLocked() error {
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bs, err := ioutil.ReadFile(c.path)
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if err != nil {
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return fmt.Errorf("reading %q: %v", c.path, err)
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}
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cert, err := tls.X509KeyPair(bs, bs)
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if err != nil {
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return fmt.Errorf("parsing %q: %v", c.path, err)
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}
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c.cert = &cert
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c.loaded = time.Now()
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return nil
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}
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// debugHandler serves a page with links to tsweb-managed debug URLs
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// at /debug/.
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func debugHandler(w http.ResponseWriter, r *http.Request) {
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f := func(format string, args ...interface{}) { fmt.Fprintf(w, format, args...) }
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f(`<html><body>
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<h1>microproxy debug</h1>
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<ul>
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`)
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f("<li><b>Hostname:</b> %v</li>\n", *hostname)
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f("<li><b>Uptime:</b> %v</li>\n", tsweb.Uptime())
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f(`<li><a href="/debug/vars">/debug/vars</a> (Go)</li>
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<li><a href="/debug/varz">/debug/varz</a> (Prometheus)</li>
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<li><a href="/debug/pprof/">/debug/pprof/</a></li>
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<li><a href="/debug/pprof/goroutine?debug=1">/debug/pprof/goroutine</a> (collapsed)</li>
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<li><a href="/debug/pprof/goroutine?debug=2">/debug/pprof/goroutine</a> (full)</li>
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<ul>
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</html>
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`)
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}
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