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tailscale/ipn/ipnlocal/serve.go

940 lines
27 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package ipnlocal
import (
"context"
"crypto/sha256"
"crypto/tls"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"io"
"mime"
"net"
"net/http"
"net/http/httputil"
"net/netip"
"net/url"
"os"
"path"
"slices"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"unicode/utf8"
"golang.org/x/net/http2"
"tailscale.com/ipn"
"tailscale.com/logtail/backoff"
"tailscale.com/net/netutil"
"tailscale.com/syncs"
"tailscale.com/tailcfg"
"tailscale.com/types/lazy"
"tailscale.com/types/logger"
"tailscale.com/util/ctxkey"
"tailscale.com/util/mak"
"tailscale.com/version"
)
const (
contentTypeHeader = "Content-Type"
grpcBaseContentType = "application/grpc"
)
// ErrETagMismatch signals that the given
// If-Match header does not match with the
// current etag of a resource.
var ErrETagMismatch = errors.New("etag mismatch")
var serveHTTPContextKey ctxkey.Key[*serveHTTPContext]
type serveHTTPContext struct {
SrcAddr netip.AddrPort
DestPort uint16
// provides funnel-specific context, nil if not funneled
Funnel *funnelFlow
}
// funnelFlow represents a funneled connection initiated via IngressPeer
// to Host.
type funnelFlow struct {
Host string
IngressPeer tailcfg.NodeView
}
// localListener is the state of host-level net.Listen for a specific (Tailscale IP, port)
// combination. If there are two TailscaleIPs (v4 and v6) and three ports being served,
// then there will be six of these active and looping in their Run method.
//
// This is not used in userspace-networking mode.
//
// localListener is used by tailscale serve (TCP only), the built-in web client and Taildrive.
// Most serve traffic and peer traffic for the web client are intercepted by netstack.
// This listener exists purely for connections from the machine itself, as that goes via the kernel,
// so we need to be in the kernel's listening/routing tables.
type localListener struct {
b *LocalBackend
ap netip.AddrPort
ctx context.Context // valid while listener is desired
cancel context.CancelFunc // for ctx, to close listener
logf logger.Logf
bo *backoff.Backoff // for retrying failed Listen calls
handler func(net.Conn) error // handler for inbound connections
closeListener syncs.AtomicValue[func() error] // Listener's Close method, if any
}
func (b *LocalBackend) newServeListener(ctx context.Context, ap netip.AddrPort, logf logger.Logf) *localListener {
ctx, cancel := context.WithCancel(ctx)
return &localListener{
b: b,
ap: ap,
ctx: ctx,
cancel: cancel,
logf: logf,
handler: func(conn net.Conn) error {
srcAddr := conn.RemoteAddr().(*net.TCPAddr).AddrPort()
handler := b.tcpHandlerForServe(ap.Port(), srcAddr, nil)
if handler == nil {
b.logf("[unexpected] local-serve: no handler for %v to port %v", srcAddr, ap.Port())
conn.Close()
return nil
}
return handler(conn)
},
bo: backoff.NewBackoff("serve-listener", logf, 30*time.Second),
}
}
// Close cancels the context and closes the listener, if any.
func (s *localListener) Close() error {
s.cancel()
if close, ok := s.closeListener.LoadOk(); ok {
s.closeListener.Store(nil)
close()
}
return nil
}
// Run starts a net.Listen for the localListener's address and port.
// If unable to listen, it retries with exponential backoff.
// Listen is retried until the context is canceled.
func (s *localListener) Run() {
for {
ip := s.ap.Addr()
ipStr := ip.String()
var lc net.ListenConfig
if initListenConfig != nil {
// On macOS, this sets the lc.Control hook to
// setsockopt the interface index to bind to. This is
// required by the network sandbox to allow binding to
// a specific interface. Without this hook, the system
// chooses a default interface to bind to.
if err := initListenConfig(&lc, ip, s.b.prevIfState, s.b.dialer.TUNName()); err != nil {
s.logf("localListener failed to init listen config %v, backing off: %v", s.ap, err)
s.bo.BackOff(s.ctx, err)
continue
}
// On macOS (AppStore or macsys) and if we're binding to a privileged port,
if version.IsSandboxedMacOS() && s.ap.Port() < 1024 {
// On macOS, we need to bind to ""/all-interfaces due to
// the network sandbox. Ideally we would only bind to the
// Tailscale interface, but macOS errors out if we try to
// to listen on privileged ports binding only to a specific
// interface. (#6364)
ipStr = ""
}
}
tcp4or6 := "tcp4"
if ip.Is6() {
tcp4or6 = "tcp6"
}
// while we were backing off and trying again, the context got canceled
// so don't bind, just return, because otherwise there will be no way
// to close this listener
if s.ctx.Err() != nil {
s.logf("localListener context closed before binding")
return
}
ln, err := lc.Listen(s.ctx, tcp4or6, net.JoinHostPort(ipStr, fmt.Sprint(s.ap.Port())))
if err != nil {
if s.shouldWarnAboutListenError(err) {
s.logf("localListener failed to listen on %v, backing off: %v", s.ap, err)
}
s.bo.BackOff(s.ctx, err)
continue
}
s.closeListener.Store(ln.Close)
s.logf("listening on %v", s.ap)
err = s.handleListenersAccept(ln)
if s.ctx.Err() != nil {
// context canceled, we're done
return
}
if err != nil {
s.logf("localListener accept error, retrying: %v", err)
}
}
}
func (s *localListener) shouldWarnAboutListenError(err error) bool {
if !s.b.sys.NetMon.Get().InterfaceState().HasIP(s.ap.Addr()) {
// Machine likely doesn't have IPv6 enabled (or the IP is still being
// assigned). No need to warn. Notably, WSL2 (Issue 6303).
return false
}
// TODO(bradfitz): check errors.Is(err, syscall.EADDRNOTAVAIL) etc? Let's
// see what happens in practice.
return true
}
// handleListenersAccept accepts connections for the Listener. It calls the
// handler in a new goroutine for each accepted connection. This is used to
// handle local "tailscale serve" and web client traffic originating from the
// machine itself.
func (s *localListener) handleListenersAccept(ln net.Listener) error {
for {
conn, err := ln.Accept()
if err != nil {
return err
}
go s.handler(conn)
}
}
// updateServeTCPPortNetMapAddrListenersLocked starts a net.Listen for configured
// Serve ports on all the node's addresses.
// Existing Listeners are closed if port no longer in incoming ports list.
//
// b.mu must be held.
func (b *LocalBackend) updateServeTCPPortNetMapAddrListenersLocked(ports []uint16) {
// close existing listeners where port
// is no longer in incoming ports list
for ap, sl := range b.serveListeners {
if !slices.Contains(ports, ap.Port()) {
b.logf("closing listener %v", ap)
sl.Close()
delete(b.serveListeners, ap)
}
}
nm := b.netMap
if nm == nil {
b.logf("netMap is nil")
return
}
if !nm.SelfNode.Valid() {
b.logf("netMap SelfNode is nil")
return
}
addrs := nm.GetAddresses()
for i := range addrs.Len() {
a := addrs.At(i)
for _, p := range ports {
addrPort := netip.AddrPortFrom(a.Addr(), p)
if _, ok := b.serveListeners[addrPort]; ok {
continue // already listening
}
sl := b.newServeListener(context.Background(), addrPort, b.logf)
mak.Set(&b.serveListeners, addrPort, sl)
go sl.Run()
}
}
}
// SetServeConfig establishes or replaces the current serve config.
// ETag is an optional parameter to enforce Optimistic Concurrency Control.
// If it is an empty string, then the config will be overwritten.
func (b *LocalBackend) SetServeConfig(config *ipn.ServeConfig, etag string) error {
b.mu.Lock()
defer b.mu.Unlock()
return b.setServeConfigLocked(config, etag)
}
func (b *LocalBackend) setServeConfigLocked(config *ipn.ServeConfig, etag string) error {
prefs := b.pm.CurrentPrefs()
if config.IsFunnelOn() && prefs.ShieldsUp() {
return errors.New("Unable to turn on Funnel while shields-up is enabled")
}
if b.isConfigLocked_Locked() {
return errors.New("can't reconfigure tailscaled when using a config file; config file is locked")
}
nm := b.netMap
if nm == nil {
return errors.New("netMap is nil")
}
if !nm.SelfNode.Valid() {
return errors.New("netMap SelfNode is nil")
}
// If etag is present, check that it has
// not changed from the last config.
prevConfig := b.serveConfig
if etag != "" {
// Note that we marshal b.serveConfig
// and not use b.lastServeConfJSON as that might
// be a Go nil value, which produces a different
// checksum from a JSON "null" value.
prevBytes, err := json.Marshal(prevConfig)
if err != nil {
return fmt.Errorf("error encoding previous config: %w", err)
}
sum := sha256.Sum256(prevBytes)
previousEtag := hex.EncodeToString(sum[:])
if etag != previousEtag {
return ErrETagMismatch
}
}
var bs []byte
if config != nil {
j, err := json.Marshal(config)
if err != nil {
return fmt.Errorf("encoding serve config: %w", err)
}
bs = j
}
profileID := b.pm.CurrentProfile().ID
confKey := ipn.ServeConfigKey(profileID)
if err := b.store.WriteState(confKey, bs); err != nil {
return fmt.Errorf("writing ServeConfig to StateStore: %w", err)
}
b.setTCPPortsInterceptedFromNetmapAndPrefsLocked(b.pm.CurrentPrefs())
// clean up and close all previously open foreground sessions
// if the current ServeConfig has overwritten them.
if prevConfig.Valid() {
has := func(string) bool { return false }
if b.serveConfig.Valid() {
has = b.serveConfig.Foreground().Contains
}
prevConfig.Foreground().Range(func(k string, v ipn.ServeConfigView) (cont bool) {
if !has(k) {
for _, sess := range b.notifyWatchers {
if sess.sessionID == k {
close(sess.ch)
}
}
}
return true
})
}
return nil
}
// ServeConfig provides a view of the current serve mappings.
// If serving is not configured, the returned view is not Valid.
func (b *LocalBackend) ServeConfig() ipn.ServeConfigView {
b.mu.Lock()
defer b.mu.Unlock()
return b.serveConfig
}
// DeleteForegroundSession deletes a ServeConfig's foreground session
// in the LocalBackend if it exists. It also ensures check, delete, and
// set operations happen within the same mutex lock to avoid any races.
func (b *LocalBackend) DeleteForegroundSession(sessionID string) error {
b.mu.Lock()
defer b.mu.Unlock()
if !b.serveConfig.Valid() || !b.serveConfig.Foreground().Contains(sessionID) {
return nil
}
sc := b.serveConfig.AsStruct()
delete(sc.Foreground, sessionID)
return b.setServeConfigLocked(sc, "")
}
// HandleIngressTCPConn handles a TCP connection initiated by the ingressPeer
// proxied to the local node over the PeerAPI.
// Target represents the destination HostPort of the conn.
// srcAddr represents the source AddrPort and not that of the ingressPeer.
// getConnOrReset is a callback to get the connection, or reset if the connection
// is no longer available.
// sendRST is a callback to send a TCP RST to the ingressPeer indicating that
// the connection was not accepted.
func (b *LocalBackend) HandleIngressTCPConn(ingressPeer tailcfg.NodeView, target ipn.HostPort, srcAddr netip.AddrPort, getConnOrReset func() (net.Conn, bool), sendRST func()) {
b.mu.Lock()
sc := b.serveConfig
b.mu.Unlock()
// TODO(maisem,bradfitz): make this not alloc for every conn.
logf := logger.WithPrefix(b.logf, "handleIngress: ")
if !sc.Valid() {
logf("got ingress conn w/o serveConfig; rejecting")
sendRST()
return
}
if !sc.HasFunnelForTarget(target) {
logf("got ingress conn for unconfigured %q; rejecting", target)
sendRST()
return
}
host, port, err := net.SplitHostPort(string(target))
if err != nil {
logf("got ingress conn for bad target %q; rejecting", target)
sendRST()
return
}
port16, err := strconv.ParseUint(port, 10, 16)
if err != nil {
logf("got ingress conn for bad target %q; rejecting", target)
sendRST()
return
}
dport := uint16(port16)
if b.getTCPHandlerForFunnelFlow != nil {
handler := b.getTCPHandlerForFunnelFlow(srcAddr, dport)
if handler != nil {
c, ok := getConnOrReset()
if !ok {
logf("getConn didn't complete from %v to port %v", srcAddr, dport)
return
}
handler(c)
return
}
}
handler := b.tcpHandlerForServe(dport, srcAddr, &funnelFlow{
Host: host,
IngressPeer: ingressPeer,
})
if handler == nil {
logf("[unexpected] no matching ingress serve handler for %v to port %v", srcAddr, dport)
sendRST()
return
}
c, ok := getConnOrReset()
if !ok {
logf("getConn didn't complete from %v to port %v", srcAddr, dport)
return
}
handler(c)
}
// tcpHandlerForServe returns a handler for a TCP connection to be served via
// the ipn.ServeConfig. The funnelFlow can be nil if this is not a funneled
// connection.
func (b *LocalBackend) tcpHandlerForServe(dport uint16, srcAddr netip.AddrPort, f *funnelFlow) (handler func(net.Conn) error) {
b.mu.Lock()
sc := b.serveConfig
b.mu.Unlock()
if !sc.Valid() {
return nil
}
tcph, ok := sc.FindTCP(dport)
if !ok {
return nil
}
if tcph.HTTPS() || tcph.HTTP() {
hs := &http.Server{
Handler: http.HandlerFunc(b.serveWebHandler),
BaseContext: func(_ net.Listener) context.Context {
return serveHTTPContextKey.WithValue(context.Background(), &serveHTTPContext{
Funnel: f,
SrcAddr: srcAddr,
DestPort: dport,
})
},
}
if tcph.HTTPS() {
hs.TLSConfig = &tls.Config{
GetCertificate: b.getTLSServeCertForPort(dport),
}
return func(c net.Conn) error {
return hs.ServeTLS(netutil.NewOneConnListener(c, nil), "", "")
}
}
return func(c net.Conn) error {
return hs.Serve(netutil.NewOneConnListener(c, nil))
}
}
if backDst := tcph.TCPForward(); backDst != "" {
return func(conn net.Conn) error {
defer conn.Close()
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
backConn, err := b.dialer.SystemDial(ctx, "tcp", backDst)
cancel()
if err != nil {
b.logf("localbackend: failed to TCP proxy port %v (from %v) to %s: %v", dport, srcAddr, backDst, err)
return nil
}
defer backConn.Close()
if sni := tcph.TerminateTLS(); sni != "" {
conn = tls.Server(conn, &tls.Config{
GetCertificate: func(hi *tls.ClientHelloInfo) (*tls.Certificate, error) {
ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
defer cancel()
pair, err := b.GetCertPEM(ctx, sni)
if err != nil {
return nil, err
}
cert, err := tls.X509KeyPair(pair.CertPEM, pair.KeyPEM)
if err != nil {
return nil, err
}
return &cert, nil
},
})
}
// TODO(bradfitz): do the RegisterIPPortIdentity and
// UnregisterIPPortIdentity stuff that netstack does
errc := make(chan error, 1)
go func() {
_, err := io.Copy(backConn, conn)
errc <- err
}()
go func() {
_, err := io.Copy(conn, backConn)
errc <- err
}()
return <-errc
}
}
return nil
}
func (b *LocalBackend) getServeHandler(r *http.Request) (_ ipn.HTTPHandlerView, at string, ok bool) {
var z ipn.HTTPHandlerView // zero value
hostname := r.Host
if r.TLS == nil {
tcd := "." + b.Status().CurrentTailnet.MagicDNSSuffix
if host, _, err := net.SplitHostPort(hostname); err == nil {
hostname = host
}
if !strings.HasSuffix(hostname, tcd) {
hostname += tcd
}
} else {
hostname = r.TLS.ServerName
}
sctx, ok := serveHTTPContextKey.ValueOk(r.Context())
if !ok {
b.logf("[unexpected] localbackend: no serveHTTPContext in request")
return z, "", false
}
wsc, ok := b.webServerConfig(hostname, sctx.DestPort)
if !ok {
return z, "", false
}
if h, ok := wsc.Handlers().GetOk(r.URL.Path); ok {
return h, r.URL.Path, true
}
pth := path.Clean(r.URL.Path)
for {
withSlash := pth + "/"
if h, ok := wsc.Handlers().GetOk(withSlash); ok {
return h, withSlash, true
}
if h, ok := wsc.Handlers().GetOk(pth); ok {
return h, pth, true
}
if pth == "/" {
return z, "", false
}
pth = path.Dir(pth)
}
}
// proxyHandlerForBackend creates a new HTTP reverse proxy for a particular backend that
// we serve requests for. `backend` is a HTTPHandler.Proxy string (url, hostport or just port).
func (b *LocalBackend) proxyHandlerForBackend(backend string) (http.Handler, error) {
targetURL, insecure := expandProxyArg(backend)
u, err := url.Parse(targetURL)
if err != nil {
return nil, fmt.Errorf("invalid url %s: %w", targetURL, err)
}
p := &reverseProxy{
logf: b.logf,
url: u,
insecure: insecure,
backend: backend,
lb: b,
}
return p, nil
}
// reverseProxy is a proxy that forwards a request to a backend host
// (preconfigured via ipn.ServeConfig). If the host is configured with
// http+insecure prefix, connection between proxy and backend will be over
// insecure TLS. If the backend host has a http prefix and the incoming request
// has application/grpc content type header, the connection will be over h2c.
// Otherwise standard Go http transport will be used.
type reverseProxy struct {
logf logger.Logf
url *url.URL
// insecure tracks whether the connection to an https backend should be
// insecure (i.e because we cannot verify its CA).
insecure bool
backend string
lb *LocalBackend
httpTransport lazy.SyncValue[*http.Transport] // transport for non-h2c backends
h2cTransport lazy.SyncValue[*http2.Transport] // transport for h2c backends
// closed tracks whether proxy is closed/currently closing.
closed atomic.Bool
}
// close ensures that any open backend connections get closed.
func (rp *reverseProxy) close() {
rp.closed.Store(true)
if h2cT := rp.h2cTransport.Get(func() *http2.Transport {
return nil
}); h2cT != nil {
h2cT.CloseIdleConnections()
}
if httpTransport := rp.httpTransport.Get(func() *http.Transport {
return nil
}); httpTransport != nil {
httpTransport.CloseIdleConnections()
}
}
func (rp *reverseProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if closed := rp.closed.Load(); closed {
rp.logf("received a request for a proxy that's being closed or has been closed")
http.Error(w, "proxy is closed", http.StatusServiceUnavailable)
return
}
p := &httputil.ReverseProxy{Rewrite: func(r *httputil.ProxyRequest) {
oldOutPath := r.Out.URL.Path
r.SetURL(rp.url)
// If mount point matches the request path exactly, the outbound
// request URL was set to empty string in serveWebHandler which
// would have resulted in the outbound path set to <proxy path>
// + '/' in SetURL. In that case, if the proxy path was set, we
// want to send the request to the <proxy path> (without the
// '/') .
if oldOutPath == "" && rp.url.Path != "" {
r.Out.URL.Path = rp.url.Path
r.Out.URL.RawPath = rp.url.RawPath
}
r.Out.Host = r.In.Host
addProxyForwardedHeaders(r)
rp.lb.addTailscaleIdentityHeaders(r)
}}
// There is no way to autodetect h2c as per RFC 9113
// https://datatracker.ietf.org/doc/html/rfc9113#name-starting-http-2.
// However, we assume that http:// proxy prefix in combination with the
// protoccol being HTTP/2 is sufficient to detect h2c for our needs. Only use this for
// gRPC to fix a known problem of plaintext gRPC backends
if rp.shouldProxyViaH2C(r) {
rp.logf("received a proxy request for plaintext gRPC")
p.Transport = rp.getH2CTransport()
} else {
p.Transport = rp.getTransport()
}
p.ServeHTTP(w, r)
}
// getTransport returns the Transport used for regular (non-GRPC) requests
// to the backend. The Transport gets created lazily, at most once.
func (rp *reverseProxy) getTransport() *http.Transport {
return rp.httpTransport.Get(func() *http.Transport {
return &http.Transport{
DialContext: rp.lb.dialer.SystemDial,
TLSClientConfig: &tls.Config{
InsecureSkipVerify: rp.insecure,
},
// Values for the following parameters have been copied from http.DefaultTransport.
ForceAttemptHTTP2: true,
MaxIdleConns: 100,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
}
})
}
// getH2CTransport returns the Transport used for GRPC requests to the backend.
// The Transport gets created lazily, at most once.
func (rp *reverseProxy) getH2CTransport() *http2.Transport {
return rp.h2cTransport.Get(func() *http2.Transport {
return &http2.Transport{
AllowHTTP: true,
DialTLSContext: func(ctx context.Context, network string, addr string, _ *tls.Config) (net.Conn, error) {
return rp.lb.dialer.SystemDial(ctx, "tcp", rp.url.Host)
},
}
})
}
// This is not a generally reliable way how to determine whether a request is
// for a h2c server, but sufficient for our particular use case.
func (rp *reverseProxy) shouldProxyViaH2C(r *http.Request) bool {
contentType := r.Header.Get(contentTypeHeader)
return r.ProtoMajor == 2 && strings.HasPrefix(rp.backend, "http://") && isGRPCContentType(contentType)
}
// isGRPC accepts an HTTP request's content type header value and determines
// whether this is gRPC content. grpc-go considers a value that equals
// application/grpc or has a prefix of application/grpc+ or application/grpc; a
// valid grpc content type header.
// https://github.com/grpc/grpc-go/blob/v1.60.0-dev/internal/grpcutil/method.go#L41-L78
func isGRPCContentType(contentType string) bool {
s, ok := strings.CutPrefix(contentType, grpcBaseContentType)
return ok && (len(s) == 0 || s[0] == '+' || s[0] == ';')
}
func addProxyForwardedHeaders(r *httputil.ProxyRequest) {
r.Out.Header.Set("X-Forwarded-Host", r.In.Host)
if r.In.TLS != nil {
r.Out.Header.Set("X-Forwarded-Proto", "https")
}
if c, ok := serveHTTPContextKey.ValueOk(r.Out.Context()); ok {
r.Out.Header.Set("X-Forwarded-For", c.SrcAddr.Addr().String())
}
}
func (b *LocalBackend) addTailscaleIdentityHeaders(r *httputil.ProxyRequest) {
// Clear any incoming values squatting in the headers.
r.Out.Header.Del("Tailscale-User-Login")
r.Out.Header.Del("Tailscale-User-Name")
r.Out.Header.Del("Tailscale-User-Profile-Pic")
r.Out.Header.Del("Tailscale-Funnel-Request")
r.Out.Header.Del("Tailscale-Headers-Info")
c, ok := serveHTTPContextKey.ValueOk(r.Out.Context())
if !ok {
return
}
if c.Funnel != nil {
r.Out.Header.Set("Tailscale-Funnel-Request", "?1")
return
}
node, user, ok := b.WhoIs("tcp", c.SrcAddr)
if !ok {
return // traffic from outside of Tailnet (funneled or local machine)
}
if node.IsTagged() {
// 2023-06-14: Not setting identity headers for tagged nodes.
// Only currently set for nodes with user identities.
return
}
r.Out.Header.Set("Tailscale-User-Login", encTailscaleHeaderValue(user.LoginName))
r.Out.Header.Set("Tailscale-User-Name", encTailscaleHeaderValue(user.DisplayName))
r.Out.Header.Set("Tailscale-User-Profile-Pic", user.ProfilePicURL)
r.Out.Header.Set("Tailscale-Headers-Info", "https://tailscale.com/s/serve-headers")
}
// encTailscaleHeaderValue cleans or encodes as necessary v, to be suitable in
// an HTTP header value. See
// https://github.com/tailscale/tailscale/issues/11603.
//
// If v is not a valid UTF-8 string, it returns an empty string.
// If v is a valid ASCII string, it returns v unmodified.
// If v is a valid UTF-8 string with non-ASCII characters, it returns a
// RFC 2047 Q-encoded string.
func encTailscaleHeaderValue(v string) string {
if !utf8.ValidString(v) {
return ""
}
return mime.QEncoding.Encode("utf-8", v)
}
// serveWebHandler is an http.HandlerFunc that maps incoming requests to the
// correct *http.
func (b *LocalBackend) serveWebHandler(w http.ResponseWriter, r *http.Request) {
h, mountPoint, 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 != "" {
b.serveFileOrDirectory(w, r, v, mountPoint)
return
}
if v := h.Proxy(); v != "" {
p, ok := b.serveProxyHandlers.Load(v)
if !ok {
http.Error(w, "unknown proxy destination", http.StatusInternalServerError)
return
}
h := p.(http.Handler)
// Trim the mount point from the URL path before proxying. (#6571)
if r.URL.Path != "/" {
h = http.StripPrefix(strings.TrimSuffix(mountPoint, "/"), h)
}
h.ServeHTTP(w, r)
return
}
http.Error(w, "empty handler", 500)
}
func (b *LocalBackend) serveFileOrDirectory(w http.ResponseWriter, r *http.Request, fileOrDir, mountPoint string) {
fi, err := os.Stat(fileOrDir)
if err != nil {
if os.IsNotExist(err) {
http.NotFound(w, r)
return
}
b.logf("error calling stat on %s: %v", fileOrDir, err)
http.Error(w, "an error occurred reading the file or directory", 500)
return
}
if fi.Mode().IsRegular() {
if mountPoint != r.URL.Path {
http.NotFound(w, r)
return
}
f, err := os.Open(fileOrDir)
if err != nil {
b.logf("error opening %s: %v", fileOrDir, err)
http.Error(w, "an error occurred reading the file or directory", 500)
return
}
defer f.Close()
http.ServeContent(w, r, path.Base(mountPoint), fi.ModTime(), f)
return
}
if !fi.IsDir() {
http.Error(w, "not a file or directory", 500)
return
}
if len(r.URL.Path) < len(mountPoint) && r.URL.Path+"/" == mountPoint {
http.Redirect(w, r, mountPoint, http.StatusFound)
return
}
var fs http.Handler = http.FileServer(http.Dir(fileOrDir))
if mountPoint != "/" {
fs = http.StripPrefix(strings.TrimSuffix(mountPoint, "/"), fs)
}
fs.ServeHTTP(&fixLocationHeaderResponseWriter{
ResponseWriter: w,
mountPoint: mountPoint,
}, r)
}
// fixLocationHeaderResponseWriter is an http.ResponseWriter wrapper that, upon
// flushing HTTP headers, prefixes any Location header with the mount point.
type fixLocationHeaderResponseWriter struct {
http.ResponseWriter
mountPoint string
fixOnce sync.Once // guards call to fix
}
func (w *fixLocationHeaderResponseWriter) fix() {
h := w.ResponseWriter.Header()
if v := h.Get("Location"); v != "" {
h.Set("Location", w.mountPoint+v)
}
}
func (w *fixLocationHeaderResponseWriter) WriteHeader(code int) {
w.fixOnce.Do(w.fix)
w.ResponseWriter.WriteHeader(code)
}
func (w *fixLocationHeaderResponseWriter) Write(p []byte) (int, error) {
w.fixOnce.Do(w.fix)
return w.ResponseWriter.Write(p)
}
// expandProxyArg returns a URL from s, where s can be of form:
//
// * port number ("8080")
// * host:port ("localhost:8080")
// * full URL ("http://localhost:8080", in which case it's returned unchanged)
// * insecure TLS ("https+insecure://127.0.0.1:4430")
func expandProxyArg(s string) (targetURL string, insecureSkipVerify bool) {
if s == "" {
return "", false
}
if strings.HasPrefix(s, "http://") || strings.HasPrefix(s, "https://") {
return s, false
}
if rest, ok := strings.CutPrefix(s, "https+insecure://"); ok {
return "https://" + rest, true
}
if allNumeric(s) {
return "http://127.0.0.1:" + s, false
}
return "http://" + s, false
}
func allNumeric(s string) bool {
for i := range len(s) {
if s[i] < '0' || s[i] > '9' {
return false
}
}
return s != ""
}
func (b *LocalBackend) webServerConfig(hostname string, port uint16) (c ipn.WebServerConfigView, ok bool) {
key := ipn.HostPort(fmt.Sprintf("%s:%v", hostname, port))
b.mu.Lock()
defer b.mu.Unlock()
if !b.serveConfig.Valid() {
return c, false
}
return b.serveConfig.FindWeb(key)
}
func (b *LocalBackend) getTLSServeCertForPort(port uint16) func(hi *tls.ClientHelloInfo) (*tls.Certificate, error) {
return func(hi *tls.ClientHelloInfo) (*tls.Certificate, error) {
if hi == nil || hi.ServerName == "" {
return nil, errors.New("no SNI ServerName")
}
_, ok := b.webServerConfig(hi.ServerName, port)
if !ok {
return nil, errors.New("no webserver configured for name/port")
}
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
}
}