// 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" "fmt" "io" "net" "net/http" "net/http/httputil" "net/netip" "net/url" pathpkg "path" "strings" "time" "tailscale.com/ipn" "tailscale.com/net/netutil" ) // serveHTTPContextKey is the context.Value key for a *serveHTTPContext. type serveHTTPContextKey struct{} type serveHTTPContext struct { SrcAddr netip.AddrPort DestPort uint16 } func (b *LocalBackend) HandleInterceptedTCPConn(dport uint16, srcAddr netip.AddrPort, getConn func() (net.Conn, bool), sendRST func()) { b.mu.Lock() sc := b.serveConfig b.mu.Unlock() if !sc.Valid() { b.logf("[unexpected] localbackend: got TCP conn w/o serveConfig; from %v to port %v", srcAddr, dport) sendRST() return } tcph, ok := sc.TCP().GetOk(int(dport)) if !ok { b.logf("[unexpected] localbackend: got TCP conn without TCP config for port %v; from %v", dport, srcAddr) sendRST() return } if tcph.HTTPS() { conn, ok := getConn() if !ok { b.logf("localbackend: getConn didn't complete from %v to port %v", srcAddr, dport) return } hs := &http.Server{ TLSConfig: &tls.Config{ GetCertificate: b.getTLSServeCertForPort(dport), }, Handler: http.HandlerFunc(b.serveWebHandler), BaseContext: func(_ net.Listener) context.Context { return context.WithValue(context.Background(), serveHTTPContextKey{}, &serveHTTPContext{ SrcAddr: srcAddr, DestPort: dport, }) }, } hs.ServeTLS(netutil.NewOneConnListener(conn, nil), "", "") return } if backDst := tcph.TCPForward(); backDst != "" { if tcph.TerminateTLS() { b.logf("TODO(bradfitz): finish") sendRST() return } 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) sendRST() return } conn, ok := getConn() if !ok { b.logf("localbackend: getConn didn't complete from %v to port %v", srcAddr, dport) backConn.Close() return } defer conn.Close() defer backConn.Close() // 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 }() <-errc return } b.logf("closing TCP conn to port %v (from %v) with actionless TCPPortHandler", dport, srcAddr) sendRST() } func (b *LocalBackend) getServeHandler(r *http.Request) (_ ipn.HTTPHandlerView, ok bool) { var z ipn.HTTPHandlerView // zero value if r.TLS == nil { return z, false } sctx, ok := r.Context().Value(serveHTTPContextKey{}).(*serveHTTPContext) if !ok { b.logf("[unexpected] localbackend: no serveHTTPContext in request") return z, false } wsc, ok := b.webServerConfig(r.TLS.ServerName, sctx.DestPort) if !ok { return z, false } path := r.URL.Path for { if h, ok := wsc.Handlers().GetOk(path); ok { return h, true } if path == "/" { return z, 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 != "" { // TODO(bradfitz): this is a lot of setup per HTTP request. We should // build the whole http.Handler with all the muxing and child handlers // only on start/config change. But this works for now (2022-11-09). u, err := url.Parse(expandProxyArg(v)) if err != nil { http.Error(w, "bad proxy config", http.StatusInternalServerError) return } rp := httputil.NewSingleHostReverseProxy(u) rp.Transport = &http.Transport{ DialContext: b.dialer.SystemDial, } rp.ServeHTTP(w, r) return } http.Error(w, "empty handler", 500) } // 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) func expandProxyArg(s string) string { if s == "" { return "" } if strings.HasPrefix(s, "http://") || strings.HasPrefix(s, "https://") { return s } if allNumeric(s) { return "http://127.0.0.1:" + s } return "http://" + s } func allNumeric(s string) bool { for i := 0; i < len(s); i++ { if s[i] < '0' || s[i] > '9' { return false } } return s != "" } func (b *LocalBackend) webServerConfig(sniName string, port uint16) (c ipn.WebServerConfigView, ok bool) { key := ipn.HostPort(fmt.Sprintf("%s:%v", sniName, port)) b.mu.Lock() defer b.mu.Unlock() if !b.serveConfig.Valid() { return c, false } return b.serveConfig.Web().GetOk(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 } }