ipn/ipnlocal: start implementing web server bits of serve

Updates tailscale/corp#7515

Change-Id: I96f4016161ba3c370492da941274c6d9a234c2bb
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/debug.go

@@ -564,7 +564,8 @@ var devStoreSetArgs struct {
 func runDevStoreSet(ctx context.Context, args []string) error {
 	// TODO(bradfitz): remove this temporary (2022-11-09) hack once
 	// profile stuff and serving CLI commands are more fleshed out.
-	if len(args) >= 1 && strings.HasPrefix(args[0], "_serve/") {
+	isServe := len(args) >= 1 && strings.HasPrefix(args[0], "_serve/")
+	if isServe {
 		st, err := localClient.StatusWithoutPeers(ctx)
 		if err != nil {
 			return err
@@ -584,6 +585,11 @@ func runDevStoreSet(ctx context.Context, args []string) error {
 		if err != nil {
 			return err
 		}
+		if isServe {
+			if err := json.Unmarshal(valb, new(ipn.ServeConfig)); err != nil {
+				return fmt.Errorf("invalid JSON: %w", err)
+			}
+		}
 		val = string(valb)
 	}
 	return localClient.SetDevStoreKeyValue(ctx, key, val)

ipn/ipn_clone.go

@@ -118,6 +118,7 @@ func (src *HTTPHandler) Clone() *HTTPHandler {
 var _HTTPHandlerCloneNeedsRegeneration = HTTPHandler(struct {
 	Path  string
 	Proxy string
+	Text  string
 }{})
 
 // Clone makes a deep copy of WebServerConfig.

ipn/ipn_view.go

@@ -285,11 +285,13 @@ func (v *HTTPHandlerView) UnmarshalJSON(b []byte) error {
 
 func (v HTTPHandlerView) Path() string  { return v.ж.Path }
 func (v HTTPHandlerView) Proxy() string { return v.ж.Proxy }
+func (v HTTPHandlerView) Text() string  { return v.ж.Text }
 
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
 var _HTTPHandlerViewNeedsRegeneration = HTTPHandler(struct {
 	Path  string
 	Proxy string
+	Text  string
 }{})
 
 // View returns a readonly view of WebServerConfig.

ipn/ipnlocal/local.go

@@ -6,7 +6,6 @@ package ipnlocal
 
 import (
 	"context"
-	"crypto/tls"
 	"encoding/base64"
 	"encoding/json"
 	"errors"
@@ -4086,41 +4085,3 @@ func (b *LocalBackend) SetDevStateStore(key, value string) error {
 func (b *LocalBackend) ShouldInterceptTCPPort(port uint16) bool {
 	return b.shouldInterceptTCPPortAtomic.Load()(port)
 }
-
-var runDevWebServer = envknob.RegisterBool("TS_DEV_WEBSERVER")
-
-func (b *LocalBackend) HandleInterceptedTCPConn(c net.Conn) {
-	if !runDevWebServer() {
-		b.logf("localbackend: closing TCP conn from %v to %v", c.RemoteAddr(), c.LocalAddr())
-		c.Close()
-		return
-	}
-
-	// TODO(bradfitz): look up how; sniff SNI if ambiguous
-	hs := &http.Server{
-		TLSConfig: &tls.Config{
-			GetCertificate: b.getTLSServeCert,
-		},
-		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			io.WriteString(w, "<h1>hello world</h1>this is tailscaled")
-		}),
-	}
-	hs.ServeTLS(netutil.NewOneConnListener(c, nil), "", "")
-}
-
-func (b *LocalBackend) getTLSServeCert(hi *tls.ClientHelloInfo) (*tls.Certificate, error) {
-	if hi == nil || hi.ServerName == "" {
-		return nil, errors.New("no SNI ServerName")
-	}
-	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
-	defer cancel()
-	pair, err := b.GetCertPEM(ctx, hi.ServerName)
-	if err != nil {
-		return nil, err
-	}
-	cert, err := tls.X509KeyPair(pair.CertPEM, pair.KeyPEM)
-	if err != nil {
-		return nil, err
-	}
-	return &cert, nil
-}

ipn/ipnlocal/serve.go

@@ -0,0 +1,107 @@
+// Copyright (c) 2022 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 ipnlocal
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"io"
+	"net"
+	"net/http"
+	pathpkg "path"
+	"time"
+
+	"tailscale.com/envknob"
+	"tailscale.com/ipn"
+	"tailscale.com/net/netutil"
+)
+
+var runDevWebServer = envknob.RegisterBool("TS_DEV_WEBSERVER")
+
+func (b *LocalBackend) HandleInterceptedTCPConn(c net.Conn) {
+	if !runDevWebServer() {
+		b.logf("localbackend: closing TCP conn from %v to %v", c.RemoteAddr(), c.LocalAddr())
+		c.Close()
+		return
+	}
+
+	// TODO(bradfitz): look up how; sniff SNI if ambiguous
+	hs := &http.Server{
+		TLSConfig: &tls.Config{
+			GetCertificate: b.getTLSServeCert,
+		},
+		Handler: http.HandlerFunc(b.serveWebHandler),
+	}
+	hs.ServeTLS(netutil.NewOneConnListener(c, nil), "", "")
+}
+
+func (b *LocalBackend) getServeHandler(r *http.Request) (_ *ipn.HTTPHandler, ok bool) {
+	if r.TLS == nil {
+		return nil, false
+	}
+
+	sni := r.TLS.ServerName
+	port := "443" // TODO(bradfitz): fix
+	key := ipn.HostPort(net.JoinHostPort(sni, port))
+
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	wsc, ok := b.serveConfig.Web[key]
+	if !ok {
+		return nil, false
+	}
+	path := r.URL.Path
+	for {
+		if h, ok := wsc.Handlers[path]; ok {
+			return h, true
+		}
+		if path == "/" {
+			return nil, false
+		}
+		path = pathpkg.Dir(path)
+	}
+}
+
+func (b *LocalBackend) serveWebHandler(w http.ResponseWriter, r *http.Request) {
+	h, ok := b.getServeHandler(r)
+	if !ok {
+		http.NotFound(w, r)
+		return
+	}
+	if s := h.Text; s != "" {
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+		io.WriteString(w, s)
+		return
+	}
+	if v := h.Path; v != "" {
+		io.WriteString(w, "TODO(bradfitz): serve file")
+		return
+	}
+	if v := h.Proxy; v != "" {
+		io.WriteString(w, "TODO(bradfitz): proxy")
+		return
+	}
+
+	http.Error(w, "empty handler", 500)
+}
+
+func (b *LocalBackend) getTLSServeCert(hi *tls.ClientHelloInfo) (*tls.Certificate, error) {
+	if hi == nil || hi.ServerName == "" {
+		return nil, errors.New("no SNI ServerName")
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+	pair, err := b.GetCertPEM(ctx, hi.ServerName)
+	if err != nil {
+		return nil, err
+	}
+	cert, err := tls.X509KeyPair(pair.CertPEM, pair.KeyPEM)
+	if err != nil {
+		return nil, err
+	}
+	return &cert, nil
+}

ipn/store.go

@@ -121,6 +121,8 @@ type HTTPHandler struct {
 	Path  string `json:",omitempty"` // absolute path to directory or file to serve
 	Proxy string `json:",omitempty"` // http://localhost:3000/, localhost:3030, 3030
 
+	Text string `json:",omitempty"` // plaintext to serve (primarily for testing)
+
 	// TODO(bradfitz): bool to not enumerate directories? TTL on mapping for
 	// temporary ones? Error codes? Redirects?
 }