Source file src/net/http/clientserver_test.go

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Tests that use both the client & server, in both HTTP/1 and HTTP/2 mode.
     6  
     7  package http_test
     8  
     9  import (
    10  	"bytes"
    11  	"compress/gzip"
    12  	"context"
    13  	"crypto/rand"
    14  	"crypto/sha1"
    15  	"crypto/tls"
    16  	"fmt"
    17  	"hash"
    18  	"io"
    19  	"log"
    20  	"maps"
    21  	"net"
    22  	. "net/http"
    23  	"net/http/httptest"
    24  	"net/http/httptrace"
    25  	"net/http/httputil"
    26  	"net/textproto"
    27  	"net/url"
    28  	"os"
    29  	"reflect"
    30  	"runtime"
    31  	"slices"
    32  	"strings"
    33  	"sync"
    34  	"sync/atomic"
    35  	"testing"
    36  	"testing/synctest"
    37  	"time"
    38  )
    39  
    40  type testMode string
    41  
    42  const (
    43  	http1Mode            = testMode("h1")            // HTTP/1.1
    44  	https1Mode           = testMode("https1")        // HTTPS/1.1
    45  	http2Mode            = testMode("h2")            // HTTP/2
    46  	http2UnencryptedMode = testMode("h2unencrypted") // HTTP/2
    47  )
    48  
    49  type testNotParallelOpt struct{}
    50  
    51  var (
    52  	testNotParallel = testNotParallelOpt{}
    53  )
    54  
    55  type TBRun[T any] interface {
    56  	testing.TB
    57  	Run(string, func(T)) bool
    58  }
    59  
    60  // run runs a client/server test in a variety of test configurations.
    61  //
    62  // Tests execute in HTTP/1.1 and HTTP/2 modes by default.
    63  // To run in a different set of configurations, pass a []testMode option.
    64  //
    65  // Tests call t.Parallel() by default.
    66  // To disable parallel execution, pass the testNotParallel option.
    67  func run[T TBRun[T]](t T, f func(t T, mode testMode), opts ...any) {
    68  	t.Helper()
    69  	modes := []testMode{http1Mode, http2Mode}
    70  	parallel := true
    71  	for _, opt := range opts {
    72  		switch opt := opt.(type) {
    73  		case []testMode:
    74  			modes = opt
    75  		case testNotParallelOpt:
    76  			parallel = false
    77  		default:
    78  			t.Fatalf("unknown option type %T", opt)
    79  		}
    80  	}
    81  	if t, ok := any(t).(*testing.T); ok && parallel {
    82  		setParallel(t)
    83  	}
    84  	for _, mode := range modes {
    85  		t.Run(string(mode), func(t T) {
    86  			t.Helper()
    87  			if t, ok := any(t).(*testing.T); ok && parallel {
    88  				setParallel(t)
    89  			}
    90  			t.Cleanup(func() {
    91  				afterTest(t)
    92  			})
    93  			f(t, mode)
    94  		})
    95  	}
    96  }
    97  
    98  // runSynctest is run combined with synctest.Run.
    99  //
   100  // The TB passed to f arranges for cleanup functions to be run in the synctest bubble.
   101  func runSynctest(t *testing.T, f func(t *testing.T, mode testMode), opts ...any) {
   102  	run(t, func(t *testing.T, mode testMode) {
   103  		synctest.Test(t, func(t *testing.T) {
   104  			f(t, mode)
   105  		})
   106  	}, opts...)
   107  }
   108  
   109  type clientServerTest struct {
   110  	t  testing.TB
   111  	h2 bool
   112  	h  Handler
   113  	ts *httptest.Server
   114  	tr *Transport
   115  	c  *Client
   116  	li *fakeNetListener
   117  }
   118  
   119  func (t *clientServerTest) close() {
   120  	t.tr.CloseIdleConnections()
   121  	t.ts.Close()
   122  }
   123  
   124  func (t *clientServerTest) getURL(u string) string {
   125  	res, err := t.c.Get(u)
   126  	if err != nil {
   127  		t.t.Fatal(err)
   128  	}
   129  	defer res.Body.Close()
   130  	slurp, err := io.ReadAll(res.Body)
   131  	if err != nil {
   132  		t.t.Fatal(err)
   133  	}
   134  	return string(slurp)
   135  }
   136  
   137  func (t *clientServerTest) scheme() string {
   138  	if t.h2 {
   139  		return "https"
   140  	}
   141  	return "http"
   142  }
   143  
   144  var optQuietLog = func(ts *httptest.Server) {
   145  	ts.Config.ErrorLog = quietLog
   146  }
   147  
   148  func optWithServerLog(lg *log.Logger) func(*httptest.Server) {
   149  	return func(ts *httptest.Server) {
   150  		ts.Config.ErrorLog = lg
   151  	}
   152  }
   153  
   154  var optFakeNet = new(struct{})
   155  
   156  // newClientServerTest creates and starts an httptest.Server.
   157  //
   158  // The mode parameter selects the implementation to test:
   159  // HTTP/1, HTTP/2, etc. Tests using newClientServerTest should use
   160  // the 'run' function, which will start a subtests for each tested mode.
   161  //
   162  // The vararg opts parameter can include functions to configure the
   163  // test server or transport.
   164  //
   165  //	func(*httptest.Server) // run before starting the server
   166  //	func(*http.Transport)
   167  //
   168  // The optFakeNet option configures the server and client to use a fake network implementation,
   169  // suitable for use in testing/synctest tests.
   170  func newClientServerTest(t testing.TB, mode testMode, h Handler, opts ...any) *clientServerTest {
   171  	if mode == http2Mode {
   172  		CondSkipHTTP2(t)
   173  	}
   174  	cst := &clientServerTest{
   175  		t:  t,
   176  		h2: mode == http2Mode,
   177  		h:  h,
   178  	}
   179  
   180  	var transportFuncs []func(*Transport)
   181  
   182  	if idx := slices.Index(opts, any(optFakeNet)); idx >= 0 {
   183  		opts = slices.Delete(opts, idx, idx+1)
   184  		cst.li = fakeNetListen()
   185  		cst.ts = &httptest.Server{
   186  			Config:   &Server{Handler: h},
   187  			Listener: cst.li,
   188  		}
   189  		transportFuncs = append(transportFuncs, func(tr *Transport) {
   190  			tr.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
   191  				return cst.li.connect(), nil
   192  			}
   193  		})
   194  	} else {
   195  		cst.ts = httptest.NewUnstartedServer(h)
   196  	}
   197  
   198  	if mode == http2UnencryptedMode {
   199  		p := &Protocols{}
   200  		p.SetUnencryptedHTTP2(true)
   201  		cst.ts.Config.Protocols = p
   202  	}
   203  
   204  	for _, opt := range opts {
   205  		switch opt := opt.(type) {
   206  		case func(*Transport):
   207  			transportFuncs = append(transportFuncs, opt)
   208  		case func(*httptest.Server):
   209  			opt(cst.ts)
   210  		default:
   211  			t.Fatalf("unhandled option type %T", opt)
   212  		}
   213  	}
   214  
   215  	if cst.ts.Config.ErrorLog == nil {
   216  		cst.ts.Config.ErrorLog = log.New(testLogWriter{t}, "", 0)
   217  	}
   218  
   219  	switch mode {
   220  	case http1Mode:
   221  		cst.ts.Start()
   222  	case https1Mode:
   223  		cst.ts.StartTLS()
   224  	case http2UnencryptedMode:
   225  		ExportHttp2ConfigureServer(cst.ts.Config, nil)
   226  		cst.ts.Start()
   227  	case http2Mode:
   228  		ExportHttp2ConfigureServer(cst.ts.Config, nil)
   229  		cst.ts.TLS = cst.ts.Config.TLSConfig
   230  		cst.ts.StartTLS()
   231  	default:
   232  		t.Fatalf("unknown test mode %v", mode)
   233  	}
   234  	cst.c = cst.ts.Client()
   235  	cst.tr = cst.c.Transport.(*Transport)
   236  	if mode == http2Mode || mode == http2UnencryptedMode {
   237  		if err := ExportHttp2ConfigureTransport(cst.tr); err != nil {
   238  			t.Fatal(err)
   239  		}
   240  	}
   241  	for _, f := range transportFuncs {
   242  		f(cst.tr)
   243  	}
   244  
   245  	if mode == http2UnencryptedMode {
   246  		p := &Protocols{}
   247  		p.SetUnencryptedHTTP2(true)
   248  		cst.tr.Protocols = p
   249  	}
   250  
   251  	t.Cleanup(func() {
   252  		cst.close()
   253  	})
   254  	return cst
   255  }
   256  
   257  type testLogWriter struct {
   258  	t testing.TB
   259  }
   260  
   261  func (w testLogWriter) Write(b []byte) (int, error) {
   262  	w.t.Logf("server log: %v", strings.TrimSpace(string(b)))
   263  	return len(b), nil
   264  }
   265  
   266  // Testing the newClientServerTest helper itself.
   267  func TestNewClientServerTest(t *testing.T) {
   268  	modes := []testMode{http1Mode, https1Mode, http2Mode}
   269  	t.Run("realnet", func(t *testing.T) {
   270  		run(t, func(t *testing.T, mode testMode) {
   271  			testNewClientServerTest(t, mode)
   272  		}, modes)
   273  	})
   274  	t.Run("synctest", func(t *testing.T) {
   275  		runSynctest(t, func(t *testing.T, mode testMode) {
   276  			testNewClientServerTest(t, mode, optFakeNet)
   277  		}, modes)
   278  	})
   279  }
   280  func testNewClientServerTest(t *testing.T, mode testMode, opts ...any) {
   281  	var got struct {
   282  		sync.Mutex
   283  		proto  string
   284  		hasTLS bool
   285  	}
   286  	h := HandlerFunc(func(w ResponseWriter, r *Request) {
   287  		got.Lock()
   288  		defer got.Unlock()
   289  		got.proto = r.Proto
   290  		got.hasTLS = r.TLS != nil
   291  	})
   292  	cst := newClientServerTest(t, mode, h, opts...)
   293  	if _, err := cst.c.Head(cst.ts.URL); err != nil {
   294  		t.Fatal(err)
   295  	}
   296  	var wantProto string
   297  	var wantTLS bool
   298  	switch mode {
   299  	case http1Mode:
   300  		wantProto = "HTTP/1.1"
   301  		wantTLS = false
   302  	case https1Mode:
   303  		wantProto = "HTTP/1.1"
   304  		wantTLS = true
   305  	case http2Mode:
   306  		wantProto = "HTTP/2.0"
   307  		wantTLS = true
   308  	}
   309  	if got.proto != wantProto {
   310  		t.Errorf("req.Proto = %q, want %q", got.proto, wantProto)
   311  	}
   312  	if got.hasTLS != wantTLS {
   313  		t.Errorf("req.TLS set: %v, want %v", got.hasTLS, wantTLS)
   314  	}
   315  }
   316  
   317  func TestChunkedResponseHeaders(t *testing.T) { run(t, testChunkedResponseHeaders) }
   318  func testChunkedResponseHeaders(t *testing.T, mode testMode) {
   319  	log.SetOutput(io.Discard) // is noisy otherwise
   320  	defer log.SetOutput(os.Stderr)
   321  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   322  		w.Header().Set("Content-Length", "intentional gibberish") // we check that this is deleted
   323  		w.(Flusher).Flush()
   324  		fmt.Fprintf(w, "I am a chunked response.")
   325  	}))
   326  
   327  	res, err := cst.c.Get(cst.ts.URL)
   328  	if err != nil {
   329  		t.Fatalf("Get error: %v", err)
   330  	}
   331  	defer res.Body.Close()
   332  	if g, e := res.ContentLength, int64(-1); g != e {
   333  		t.Errorf("expected ContentLength of %d; got %d", e, g)
   334  	}
   335  	wantTE := []string{"chunked"}
   336  	if mode == http2Mode {
   337  		wantTE = nil
   338  	}
   339  	if !slices.Equal(res.TransferEncoding, wantTE) {
   340  		t.Errorf("TransferEncoding = %v; want %v", res.TransferEncoding, wantTE)
   341  	}
   342  	if got, haveCL := res.Header["Content-Length"]; haveCL {
   343  		t.Errorf("Unexpected Content-Length: %q", got)
   344  	}
   345  }
   346  
   347  type reqFunc func(c *Client, url string) (*Response, error)
   348  
   349  // h12Compare is a test that compares HTTP/1 and HTTP/2 behavior
   350  // against each other.
   351  type h12Compare struct {
   352  	Handler            func(ResponseWriter, *Request)    // required
   353  	ReqFunc            reqFunc                           // optional
   354  	CheckResponse      func(proto string, res *Response) // optional
   355  	EarlyCheckResponse func(proto string, res *Response) // optional; pre-normalize
   356  	Opts               []any
   357  }
   358  
   359  func (tt h12Compare) reqFunc() reqFunc {
   360  	if tt.ReqFunc == nil {
   361  		return (*Client).Get
   362  	}
   363  	return tt.ReqFunc
   364  }
   365  
   366  func (tt h12Compare) run(t *testing.T) {
   367  	setParallel(t)
   368  	cst1 := newClientServerTest(t, http1Mode, HandlerFunc(tt.Handler), tt.Opts...)
   369  	defer cst1.close()
   370  	cst2 := newClientServerTest(t, http2Mode, HandlerFunc(tt.Handler), tt.Opts...)
   371  	defer cst2.close()
   372  
   373  	res1, err := tt.reqFunc()(cst1.c, cst1.ts.URL)
   374  	if err != nil {
   375  		t.Errorf("HTTP/1 request: %v", err)
   376  		return
   377  	}
   378  	res2, err := tt.reqFunc()(cst2.c, cst2.ts.URL)
   379  	if err != nil {
   380  		t.Errorf("HTTP/2 request: %v", err)
   381  		return
   382  	}
   383  
   384  	if fn := tt.EarlyCheckResponse; fn != nil {
   385  		fn("HTTP/1.1", res1)
   386  		fn("HTTP/2.0", res2)
   387  	}
   388  
   389  	tt.normalizeRes(t, res1, "HTTP/1.1")
   390  	tt.normalizeRes(t, res2, "HTTP/2.0")
   391  	res1body, res2body := res1.Body, res2.Body
   392  
   393  	eres1 := mostlyCopy(res1)
   394  	eres2 := mostlyCopy(res2)
   395  	if !reflect.DeepEqual(eres1, eres2) {
   396  		t.Errorf("Response headers to handler differed:\nhttp/1 (%v):\n\t%#v\nhttp/2 (%v):\n\t%#v",
   397  			cst1.ts.URL, eres1, cst2.ts.URL, eres2)
   398  	}
   399  	if !reflect.DeepEqual(res1body, res2body) {
   400  		t.Errorf("Response bodies to handler differed.\nhttp1: %v\nhttp2: %v\n", res1body, res2body)
   401  	}
   402  	if fn := tt.CheckResponse; fn != nil {
   403  		res1.Body, res2.Body = res1body, res2body
   404  		fn("HTTP/1.1", res1)
   405  		fn("HTTP/2.0", res2)
   406  	}
   407  }
   408  
   409  func mostlyCopy(r *Response) *Response {
   410  	c := *r
   411  	c.Body = nil
   412  	c.TransferEncoding = nil
   413  	c.TLS = nil
   414  	c.Request = nil
   415  	return &c
   416  }
   417  
   418  type slurpResult struct {
   419  	io.ReadCloser
   420  	body []byte
   421  	err  error
   422  }
   423  
   424  func (sr slurpResult) String() string { return fmt.Sprintf("body %q; err %v", sr.body, sr.err) }
   425  
   426  func (tt h12Compare) normalizeRes(t *testing.T, res *Response, wantProto string) {
   427  	if res.Proto == wantProto || res.Proto == "HTTP/IGNORE" {
   428  		res.Proto, res.ProtoMajor, res.ProtoMinor = "", 0, 0
   429  	} else {
   430  		t.Errorf("got %q response; want %q", res.Proto, wantProto)
   431  	}
   432  	slurp, err := io.ReadAll(res.Body)
   433  
   434  	res.Body.Close()
   435  	res.Body = slurpResult{
   436  		ReadCloser: io.NopCloser(bytes.NewReader(slurp)),
   437  		body:       slurp,
   438  		err:        err,
   439  	}
   440  	for i, v := range res.Header["Date"] {
   441  		res.Header["Date"][i] = strings.Repeat("x", len(v))
   442  	}
   443  	if res.Request == nil {
   444  		t.Errorf("for %s, no request", wantProto)
   445  	}
   446  	if (res.TLS != nil) != (wantProto == "HTTP/2.0") {
   447  		t.Errorf("TLS set = %v; want %v", res.TLS != nil, res.TLS == nil)
   448  	}
   449  }
   450  
   451  // Issue 13532
   452  func TestH12_HeadContentLengthNoBody(t *testing.T) {
   453  	h12Compare{
   454  		ReqFunc: (*Client).Head,
   455  		Handler: func(w ResponseWriter, r *Request) {
   456  		},
   457  	}.run(t)
   458  }
   459  
   460  func TestH12_HeadContentLengthSmallBody(t *testing.T) {
   461  	h12Compare{
   462  		ReqFunc: (*Client).Head,
   463  		Handler: func(w ResponseWriter, r *Request) {
   464  			io.WriteString(w, "small")
   465  		},
   466  	}.run(t)
   467  }
   468  
   469  func TestH12_HeadContentLengthLargeBody(t *testing.T) {
   470  	h12Compare{
   471  		ReqFunc: (*Client).Head,
   472  		Handler: func(w ResponseWriter, r *Request) {
   473  			chunk := strings.Repeat("x", 512<<10)
   474  			for i := 0; i < 10; i++ {
   475  				io.WriteString(w, chunk)
   476  			}
   477  		},
   478  	}.run(t)
   479  }
   480  
   481  func TestH12_200NoBody(t *testing.T) {
   482  	h12Compare{Handler: func(w ResponseWriter, r *Request) {}}.run(t)
   483  }
   484  
   485  func TestH2_204NoBody(t *testing.T) { testH12_noBody(t, 204) }
   486  func TestH2_304NoBody(t *testing.T) { testH12_noBody(t, 304) }
   487  func TestH2_404NoBody(t *testing.T) { testH12_noBody(t, 404) }
   488  
   489  func testH12_noBody(t *testing.T, status int) {
   490  	h12Compare{Handler: func(w ResponseWriter, r *Request) {
   491  		w.WriteHeader(status)
   492  	}}.run(t)
   493  }
   494  
   495  func TestH12_SmallBody(t *testing.T) {
   496  	h12Compare{Handler: func(w ResponseWriter, r *Request) {
   497  		io.WriteString(w, "small body")
   498  	}}.run(t)
   499  }
   500  
   501  func TestH12_ExplicitContentLength(t *testing.T) {
   502  	h12Compare{Handler: func(w ResponseWriter, r *Request) {
   503  		w.Header().Set("Content-Length", "3")
   504  		io.WriteString(w, "foo")
   505  	}}.run(t)
   506  }
   507  
   508  func TestH12_FlushBeforeBody(t *testing.T) {
   509  	h12Compare{Handler: func(w ResponseWriter, r *Request) {
   510  		w.(Flusher).Flush()
   511  		io.WriteString(w, "foo")
   512  	}}.run(t)
   513  }
   514  
   515  func TestH12_FlushMidBody(t *testing.T) {
   516  	h12Compare{Handler: func(w ResponseWriter, r *Request) {
   517  		io.WriteString(w, "foo")
   518  		w.(Flusher).Flush()
   519  		io.WriteString(w, "bar")
   520  	}}.run(t)
   521  }
   522  
   523  func TestH12_Head_ExplicitLen(t *testing.T) {
   524  	h12Compare{
   525  		ReqFunc: (*Client).Head,
   526  		Handler: func(w ResponseWriter, r *Request) {
   527  			if r.Method != "HEAD" {
   528  				t.Errorf("unexpected method %q", r.Method)
   529  			}
   530  			w.Header().Set("Content-Length", "1235")
   531  		},
   532  	}.run(t)
   533  }
   534  
   535  func TestH12_Head_ImplicitLen(t *testing.T) {
   536  	h12Compare{
   537  		ReqFunc: (*Client).Head,
   538  		Handler: func(w ResponseWriter, r *Request) {
   539  			if r.Method != "HEAD" {
   540  				t.Errorf("unexpected method %q", r.Method)
   541  			}
   542  			io.WriteString(w, "foo")
   543  		},
   544  	}.run(t)
   545  }
   546  
   547  func TestH12_HandlerWritesTooLittle(t *testing.T) {
   548  	h12Compare{
   549  		Handler: func(w ResponseWriter, r *Request) {
   550  			w.Header().Set("Content-Length", "3")
   551  			io.WriteString(w, "12") // one byte short
   552  		},
   553  		CheckResponse: func(proto string, res *Response) {
   554  			sr, ok := res.Body.(slurpResult)
   555  			if !ok {
   556  				t.Errorf("%s body is %T; want slurpResult", proto, res.Body)
   557  				return
   558  			}
   559  			if sr.err != io.ErrUnexpectedEOF {
   560  				t.Errorf("%s read error = %v; want io.ErrUnexpectedEOF", proto, sr.err)
   561  			}
   562  			if string(sr.body) != "12" {
   563  				t.Errorf("%s body = %q; want %q", proto, sr.body, "12")
   564  			}
   565  		},
   566  	}.run(t)
   567  }
   568  
   569  // Tests that the HTTP/1 and HTTP/2 servers prevent handlers from
   570  // writing more than they declared. This test does not test whether
   571  // the transport deals with too much data, though, since the server
   572  // doesn't make it possible to send bogus data. For those tests, see
   573  // transport_test.go (for HTTP/1) or x/net/http2/transport_test.go
   574  // (for HTTP/2).
   575  func TestHandlerWritesTooMuch(t *testing.T) { run(t, testHandlerWritesTooMuch) }
   576  func testHandlerWritesTooMuch(t *testing.T, mode testMode) {
   577  	wantBody := []byte("123")
   578  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   579  		rc := NewResponseController(w)
   580  		w.Header().Set("Content-Length", fmt.Sprintf("%v", len(wantBody)))
   581  		rc.Flush()
   582  		w.Write(wantBody)
   583  		rc.Flush()
   584  		n, err := io.WriteString(w, "x") // too many
   585  		if err == nil {
   586  			err = rc.Flush()
   587  		}
   588  		// TODO: Check that this is ErrContentLength, not just any error.
   589  		if err == nil {
   590  			t.Errorf("for proto %q, final write = %v, %v; want _, some error", r.Proto, n, err)
   591  		}
   592  	}))
   593  
   594  	res, err := cst.c.Get(cst.ts.URL)
   595  	if err != nil {
   596  		t.Fatal(err)
   597  	}
   598  	defer res.Body.Close()
   599  
   600  	gotBody, _ := io.ReadAll(res.Body)
   601  	if !bytes.Equal(gotBody, wantBody) {
   602  		t.Fatalf("got response body: %q; want %q", gotBody, wantBody)
   603  	}
   604  }
   605  
   606  // Verify that both our HTTP/1 and HTTP/2 request and auto-decompress gzip.
   607  // Some hosts send gzip even if you don't ask for it; see golang.org/issue/13298
   608  func TestH12_AutoGzip(t *testing.T) {
   609  	h12Compare{
   610  		Handler: func(w ResponseWriter, r *Request) {
   611  			if ae := r.Header.Get("Accept-Encoding"); ae != "gzip" {
   612  				t.Errorf("%s Accept-Encoding = %q; want gzip", r.Proto, ae)
   613  			}
   614  			w.Header().Set("Content-Encoding", "gzip")
   615  			gz := gzip.NewWriter(w)
   616  			io.WriteString(gz, "I am some gzipped content. Go go go go go go go go go go go go should compress well.")
   617  			gz.Close()
   618  		},
   619  	}.run(t)
   620  }
   621  
   622  func TestH12_AutoGzip_Disabled(t *testing.T) {
   623  	h12Compare{
   624  		Opts: []any{
   625  			func(tr *Transport) { tr.DisableCompression = true },
   626  		},
   627  		Handler: func(w ResponseWriter, r *Request) {
   628  			fmt.Fprintf(w, "%q", r.Header["Accept-Encoding"])
   629  			if ae := r.Header.Get("Accept-Encoding"); ae != "" {
   630  				t.Errorf("%s Accept-Encoding = %q; want empty", r.Proto, ae)
   631  			}
   632  		},
   633  	}.run(t)
   634  }
   635  
   636  // Test304Responses verifies that 304s don't declare that they're
   637  // chunking in their response headers and aren't allowed to produce
   638  // output.
   639  func Test304Responses(t *testing.T) { run(t, test304Responses) }
   640  func test304Responses(t *testing.T, mode testMode) {
   641  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   642  		w.WriteHeader(StatusNotModified)
   643  		_, err := w.Write([]byte("illegal body"))
   644  		if err != ErrBodyNotAllowed {
   645  			t.Errorf("on Write, expected ErrBodyNotAllowed, got %v", err)
   646  		}
   647  	}))
   648  	defer cst.close()
   649  	res, err := cst.c.Get(cst.ts.URL)
   650  	if err != nil {
   651  		t.Fatal(err)
   652  	}
   653  	if len(res.TransferEncoding) > 0 {
   654  		t.Errorf("expected no TransferEncoding; got %v", res.TransferEncoding)
   655  	}
   656  	body, err := io.ReadAll(res.Body)
   657  	if err != nil {
   658  		t.Error(err)
   659  	}
   660  	if len(body) > 0 {
   661  		t.Errorf("got unexpected body %q", string(body))
   662  	}
   663  }
   664  
   665  func TestH12_ServerEmptyContentLength(t *testing.T) {
   666  	h12Compare{
   667  		Handler: func(w ResponseWriter, r *Request) {
   668  			w.Header()["Content-Type"] = []string{""}
   669  			io.WriteString(w, "<html><body>hi</body></html>")
   670  		},
   671  	}.run(t)
   672  }
   673  
   674  func TestH12_RequestContentLength_Known_NonZero(t *testing.T) {
   675  	h12requestContentLength(t, func() io.Reader { return strings.NewReader("FOUR") }, 4)
   676  }
   677  
   678  func TestH12_RequestContentLength_Known_Zero(t *testing.T) {
   679  	h12requestContentLength(t, func() io.Reader { return nil }, 0)
   680  }
   681  
   682  func TestH12_RequestContentLength_Unknown(t *testing.T) {
   683  	h12requestContentLength(t, func() io.Reader { return struct{ io.Reader }{strings.NewReader("Stuff")} }, -1)
   684  }
   685  
   686  func h12requestContentLength(t *testing.T, bodyfn func() io.Reader, wantLen int64) {
   687  	h12Compare{
   688  		Handler: func(w ResponseWriter, r *Request) {
   689  			w.Header().Set("Got-Length", fmt.Sprint(r.ContentLength))
   690  			fmt.Fprintf(w, "Req.ContentLength=%v", r.ContentLength)
   691  		},
   692  		ReqFunc: func(c *Client, url string) (*Response, error) {
   693  			return c.Post(url, "text/plain", bodyfn())
   694  		},
   695  		CheckResponse: func(proto string, res *Response) {
   696  			if got, want := res.Header.Get("Got-Length"), fmt.Sprint(wantLen); got != want {
   697  				t.Errorf("Proto %q got length %q; want %q", proto, got, want)
   698  			}
   699  		},
   700  	}.run(t)
   701  }
   702  
   703  // Tests that closing the Request.Cancel channel also while still
   704  // reading the response body. Issue 13159.
   705  func TestCancelRequestMidBody(t *testing.T) { run(t, testCancelRequestMidBody) }
   706  func testCancelRequestMidBody(t *testing.T, mode testMode) {
   707  	unblock := make(chan bool)
   708  	didFlush := make(chan bool, 1)
   709  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   710  		io.WriteString(w, "Hello")
   711  		w.(Flusher).Flush()
   712  		didFlush <- true
   713  		<-unblock
   714  		io.WriteString(w, ", world.")
   715  	}))
   716  	defer close(unblock)
   717  
   718  	req, _ := NewRequest("GET", cst.ts.URL, nil)
   719  	cancel := make(chan struct{})
   720  	req.Cancel = cancel
   721  
   722  	res, err := cst.c.Do(req)
   723  	if err != nil {
   724  		t.Fatal(err)
   725  	}
   726  	defer res.Body.Close()
   727  	<-didFlush
   728  
   729  	// Read a bit before we cancel. (Issue 13626)
   730  	// We should have "Hello" at least sitting there.
   731  	firstRead := make([]byte, 10)
   732  	n, err := res.Body.Read(firstRead)
   733  	if err != nil {
   734  		t.Fatal(err)
   735  	}
   736  	firstRead = firstRead[:n]
   737  
   738  	close(cancel)
   739  
   740  	rest, err := io.ReadAll(res.Body)
   741  	all := string(firstRead) + string(rest)
   742  	if all != "Hello" {
   743  		t.Errorf("Read %q (%q + %q); want Hello", all, firstRead, rest)
   744  	}
   745  	if err != ExportErrRequestCanceled {
   746  		t.Errorf("ReadAll error = %v; want %v", err, ExportErrRequestCanceled)
   747  	}
   748  }
   749  
   750  // Tests that clients can send trailers to a server and that the server can read them.
   751  func TestTrailersClientToServer(t *testing.T) { run(t, testTrailersClientToServer) }
   752  func testTrailersClientToServer(t *testing.T, mode testMode) {
   753  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   754  		slurp, err := io.ReadAll(r.Body)
   755  		if err != nil {
   756  			t.Errorf("Server reading request body: %v", err)
   757  		}
   758  		if string(slurp) != "foo" {
   759  			t.Errorf("Server read request body %q; want foo", slurp)
   760  		}
   761  		if r.Trailer == nil {
   762  			io.WriteString(w, "nil Trailer")
   763  		} else {
   764  			decl := slices.Sorted(maps.Keys(r.Trailer))
   765  			fmt.Fprintf(w, "decl: %v, vals: %s, %s",
   766  				decl,
   767  				r.Trailer.Get("Client-Trailer-A"),
   768  				r.Trailer.Get("Client-Trailer-B"))
   769  		}
   770  	}))
   771  
   772  	var req *Request
   773  	req, _ = NewRequest("POST", cst.ts.URL, io.MultiReader(
   774  		eofReaderFunc(func() {
   775  			req.Trailer["Client-Trailer-A"] = []string{"valuea"}
   776  		}),
   777  		strings.NewReader("foo"),
   778  		eofReaderFunc(func() {
   779  			req.Trailer["Client-Trailer-B"] = []string{"valueb"}
   780  		}),
   781  	))
   782  	req.Trailer = Header{
   783  		"Client-Trailer-A": nil, //  to be set later
   784  		"Client-Trailer-B": nil, //  to be set later
   785  	}
   786  	req.ContentLength = -1
   787  	res, err := cst.c.Do(req)
   788  	if err != nil {
   789  		t.Fatal(err)
   790  	}
   791  	if err := wantBody(res, err, "decl: [Client-Trailer-A Client-Trailer-B], vals: valuea, valueb"); err != nil {
   792  		t.Error(err)
   793  	}
   794  }
   795  
   796  // Tests that servers send trailers to a client and that the client can read them.
   797  func TestTrailersServerToClient(t *testing.T) {
   798  	run(t, func(t *testing.T, mode testMode) {
   799  		testTrailersServerToClient(t, mode, false)
   800  	})
   801  }
   802  func TestTrailersServerToClientFlush(t *testing.T) {
   803  	run(t, func(t *testing.T, mode testMode) {
   804  		testTrailersServerToClient(t, mode, true)
   805  	})
   806  }
   807  
   808  func testTrailersServerToClient(t *testing.T, mode testMode, flush bool) {
   809  	const body = "Some body"
   810  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   811  		w.Header().Set("Trailer", "Server-Trailer-A, Server-Trailer-B")
   812  		w.Header().Add("Trailer", "Server-Trailer-C")
   813  
   814  		io.WriteString(w, body)
   815  		if flush {
   816  			w.(Flusher).Flush()
   817  		}
   818  
   819  		// How handlers set Trailers: declare it ahead of time
   820  		// with the Trailer header, and then mutate the
   821  		// Header() of those values later, after the response
   822  		// has been written (we wrote to w above).
   823  		w.Header().Set("Server-Trailer-A", "valuea")
   824  		w.Header().Set("Server-Trailer-C", "valuec") // skipping B
   825  		w.Header().Set("Server-Trailer-NotDeclared", "should be omitted")
   826  	}))
   827  
   828  	res, err := cst.c.Get(cst.ts.URL)
   829  	if err != nil {
   830  		t.Fatal(err)
   831  	}
   832  
   833  	wantHeader := Header{
   834  		"Content-Type": {"text/plain; charset=utf-8"},
   835  	}
   836  	wantLen := -1
   837  	if mode == http2Mode && !flush {
   838  		// In HTTP/1.1, any use of trailers forces HTTP/1.1
   839  		// chunking and a flush at the first write. That's
   840  		// unnecessary with HTTP/2's framing, so the server
   841  		// is able to calculate the length while still sending
   842  		// trailers afterwards.
   843  		wantLen = len(body)
   844  		wantHeader["Content-Length"] = []string{fmt.Sprint(wantLen)}
   845  	}
   846  	if res.ContentLength != int64(wantLen) {
   847  		t.Errorf("ContentLength = %v; want %v", res.ContentLength, wantLen)
   848  	}
   849  
   850  	delete(res.Header, "Date") // irrelevant for test
   851  	if !reflect.DeepEqual(res.Header, wantHeader) {
   852  		t.Errorf("Header = %v; want %v", res.Header, wantHeader)
   853  	}
   854  
   855  	if got, want := res.Trailer, (Header{
   856  		"Server-Trailer-A": nil,
   857  		"Server-Trailer-B": nil,
   858  		"Server-Trailer-C": nil,
   859  	}); !reflect.DeepEqual(got, want) {
   860  		t.Errorf("Trailer before body read = %v; want %v", got, want)
   861  	}
   862  
   863  	if err := wantBody(res, nil, body); err != nil {
   864  		t.Fatal(err)
   865  	}
   866  
   867  	if got, want := res.Trailer, (Header{
   868  		"Server-Trailer-A": {"valuea"},
   869  		"Server-Trailer-B": nil,
   870  		"Server-Trailer-C": {"valuec"},
   871  	}); !reflect.DeepEqual(got, want) {
   872  		t.Errorf("Trailer after body read = %v; want %v", got, want)
   873  	}
   874  }
   875  
   876  // Don't allow a Body.Read after Body.Close. Issue 13648.
   877  func TestResponseBodyReadAfterClose(t *testing.T) { run(t, testResponseBodyReadAfterClose) }
   878  func testResponseBodyReadAfterClose(t *testing.T, mode testMode) {
   879  	const body = "Some body"
   880  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   881  		io.WriteString(w, body)
   882  	}))
   883  	res, err := cst.c.Get(cst.ts.URL)
   884  	if err != nil {
   885  		t.Fatal(err)
   886  	}
   887  	res.Body.Close()
   888  	data, err := io.ReadAll(res.Body)
   889  	if len(data) != 0 || err == nil {
   890  		t.Fatalf("ReadAll returned %q, %v; want error", data, err)
   891  	}
   892  }
   893  
   894  func TestConcurrentReadWriteReqBody(t *testing.T) { run(t, testConcurrentReadWriteReqBody) }
   895  func testConcurrentReadWriteReqBody(t *testing.T, mode testMode) {
   896  	const reqBody = "some request body"
   897  	const resBody = "some response body"
   898  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   899  		var wg sync.WaitGroup
   900  		wg.Add(2)
   901  		didRead := make(chan bool, 1)
   902  		// Read in one goroutine.
   903  		go func() {
   904  			defer wg.Done()
   905  			data, err := io.ReadAll(r.Body)
   906  			if string(data) != reqBody {
   907  				t.Errorf("Handler read %q; want %q", data, reqBody)
   908  			}
   909  			if err != nil {
   910  				t.Errorf("Handler Read: %v", err)
   911  			}
   912  			didRead <- true
   913  		}()
   914  		// Write in another goroutine.
   915  		go func() {
   916  			defer wg.Done()
   917  			if mode != http2Mode {
   918  				// our HTTP/1 implementation intentionally
   919  				// doesn't permit writes during read (mostly
   920  				// due to it being undefined); if that is ever
   921  				// relaxed, change this.
   922  				<-didRead
   923  			}
   924  			io.WriteString(w, resBody)
   925  		}()
   926  		wg.Wait()
   927  	}))
   928  	req, _ := NewRequest("POST", cst.ts.URL, strings.NewReader(reqBody))
   929  	req.Header.Add("Expect", "100-continue") // just to complicate things
   930  	res, err := cst.c.Do(req)
   931  	if err != nil {
   932  		t.Fatal(err)
   933  	}
   934  	data, err := io.ReadAll(res.Body)
   935  	defer res.Body.Close()
   936  	if err != nil {
   937  		t.Fatal(err)
   938  	}
   939  	if string(data) != resBody {
   940  		t.Errorf("read %q; want %q", data, resBody)
   941  	}
   942  }
   943  
   944  func TestConnectRequest(t *testing.T) { run(t, testConnectRequest) }
   945  func testConnectRequest(t *testing.T, mode testMode) {
   946  	gotc := make(chan *Request, 1)
   947  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
   948  		gotc <- r
   949  	}))
   950  
   951  	u, err := url.Parse(cst.ts.URL)
   952  	if err != nil {
   953  		t.Fatal(err)
   954  	}
   955  
   956  	tests := []struct {
   957  		req  *Request
   958  		want string
   959  	}{
   960  		{
   961  			req: &Request{
   962  				Method: "CONNECT",
   963  				Header: Header{},
   964  				URL:    u,
   965  			},
   966  			want: u.Host,
   967  		},
   968  		{
   969  			req: &Request{
   970  				Method: "CONNECT",
   971  				Header: Header{},
   972  				URL:    u,
   973  				Host:   "example.com:123",
   974  			},
   975  			want: "example.com:123",
   976  		},
   977  	}
   978  
   979  	for i, tt := range tests {
   980  		res, err := cst.c.Do(tt.req)
   981  		if err != nil {
   982  			t.Errorf("%d. RoundTrip = %v", i, err)
   983  			continue
   984  		}
   985  		res.Body.Close()
   986  		req := <-gotc
   987  		if req.Method != "CONNECT" {
   988  			t.Errorf("method = %q; want CONNECT", req.Method)
   989  		}
   990  		if req.Host != tt.want {
   991  			t.Errorf("Host = %q; want %q", req.Host, tt.want)
   992  		}
   993  		if req.URL.Host != tt.want {
   994  			t.Errorf("URL.Host = %q; want %q", req.URL.Host, tt.want)
   995  		}
   996  	}
   997  }
   998  
   999  func TestTransportUserAgent(t *testing.T) { run(t, testTransportUserAgent) }
  1000  func testTransportUserAgent(t *testing.T, mode testMode) {
  1001  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1002  		fmt.Fprintf(w, "%q", r.Header["User-Agent"])
  1003  	}))
  1004  
  1005  	either := func(a, b string) string {
  1006  		if mode == http2Mode {
  1007  			return b
  1008  		}
  1009  		return a
  1010  	}
  1011  
  1012  	tests := []struct {
  1013  		setup func(*Request)
  1014  		want  string
  1015  	}{
  1016  		{
  1017  			func(r *Request) {},
  1018  			either(`["Go-http-client/1.1"]`, `["Go-http-client/2.0"]`),
  1019  		},
  1020  		{
  1021  			func(r *Request) { r.Header.Set("User-Agent", "foo/1.2.3") },
  1022  			`["foo/1.2.3"]`,
  1023  		},
  1024  		{
  1025  			func(r *Request) { r.Header["User-Agent"] = []string{"single", "or", "multiple"} },
  1026  			`["single"]`,
  1027  		},
  1028  		{
  1029  			func(r *Request) { r.Header.Set("User-Agent", "") },
  1030  			`[]`,
  1031  		},
  1032  		{
  1033  			func(r *Request) { r.Header["User-Agent"] = nil },
  1034  			`[]`,
  1035  		},
  1036  	}
  1037  	for i, tt := range tests {
  1038  		req, _ := NewRequest("GET", cst.ts.URL, nil)
  1039  		tt.setup(req)
  1040  		res, err := cst.c.Do(req)
  1041  		if err != nil {
  1042  			t.Errorf("%d. RoundTrip = %v", i, err)
  1043  			continue
  1044  		}
  1045  		slurp, err := io.ReadAll(res.Body)
  1046  		res.Body.Close()
  1047  		if err != nil {
  1048  			t.Errorf("%d. read body = %v", i, err)
  1049  			continue
  1050  		}
  1051  		if string(slurp) != tt.want {
  1052  			t.Errorf("%d. body mismatch.\n got: %s\nwant: %s\n", i, slurp, tt.want)
  1053  		}
  1054  	}
  1055  }
  1056  
  1057  func TestStarRequestMethod(t *testing.T) {
  1058  	for _, method := range []string{"FOO", "OPTIONS"} {
  1059  		t.Run(method, func(t *testing.T) {
  1060  			run(t, func(t *testing.T, mode testMode) {
  1061  				testStarRequest(t, method, mode)
  1062  			})
  1063  		})
  1064  	}
  1065  }
  1066  func testStarRequest(t *testing.T, method string, mode testMode) {
  1067  	gotc := make(chan *Request, 1)
  1068  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1069  		w.Header().Set("foo", "bar")
  1070  		gotc <- r
  1071  		w.(Flusher).Flush()
  1072  	}))
  1073  
  1074  	u, err := url.Parse(cst.ts.URL)
  1075  	if err != nil {
  1076  		t.Fatal(err)
  1077  	}
  1078  	u.Path = "*"
  1079  
  1080  	req := &Request{
  1081  		Method: method,
  1082  		Header: Header{},
  1083  		URL:    u,
  1084  	}
  1085  
  1086  	res, err := cst.c.Do(req)
  1087  	if err != nil {
  1088  		t.Fatalf("RoundTrip = %v", err)
  1089  	}
  1090  	res.Body.Close()
  1091  
  1092  	wantFoo := "bar"
  1093  	wantLen := int64(-1)
  1094  	if method == "OPTIONS" {
  1095  		wantFoo = ""
  1096  		wantLen = 0
  1097  	}
  1098  	if res.StatusCode != 200 {
  1099  		t.Errorf("status code = %v; want %d", res.Status, 200)
  1100  	}
  1101  	if res.ContentLength != wantLen {
  1102  		t.Errorf("content length = %v; want %d", res.ContentLength, wantLen)
  1103  	}
  1104  	if got := res.Header.Get("foo"); got != wantFoo {
  1105  		t.Errorf("response \"foo\" header = %q; want %q", got, wantFoo)
  1106  	}
  1107  	select {
  1108  	case req = <-gotc:
  1109  	default:
  1110  		req = nil
  1111  	}
  1112  	if req == nil {
  1113  		if method != "OPTIONS" {
  1114  			t.Fatalf("handler never got request")
  1115  		}
  1116  		return
  1117  	}
  1118  	if req.Method != method {
  1119  		t.Errorf("method = %q; want %q", req.Method, method)
  1120  	}
  1121  	if req.URL.Path != "*" {
  1122  		t.Errorf("URL.Path = %q; want *", req.URL.Path)
  1123  	}
  1124  	if req.RequestURI != "*" {
  1125  		t.Errorf("RequestURI = %q; want *", req.RequestURI)
  1126  	}
  1127  }
  1128  
  1129  // Issue 13957
  1130  func TestTransportDiscardsUnneededConns(t *testing.T) {
  1131  	run(t, testTransportDiscardsUnneededConns, []testMode{http2Mode})
  1132  }
  1133  func testTransportDiscardsUnneededConns(t *testing.T, mode testMode) {
  1134  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1135  		fmt.Fprintf(w, "Hello, %v", r.RemoteAddr)
  1136  	}))
  1137  	defer cst.close()
  1138  
  1139  	var numOpen, numClose int32 // atomic
  1140  
  1141  	tlsConfig := &tls.Config{InsecureSkipVerify: true}
  1142  	tr := &Transport{
  1143  		TLSClientConfig: tlsConfig,
  1144  		DialTLS: func(_, addr string) (net.Conn, error) {
  1145  			time.Sleep(10 * time.Millisecond)
  1146  			rc, err := net.Dial("tcp", addr)
  1147  			if err != nil {
  1148  				return nil, err
  1149  			}
  1150  			atomic.AddInt32(&numOpen, 1)
  1151  			c := noteCloseConn{rc, func() { atomic.AddInt32(&numClose, 1) }}
  1152  			return tls.Client(c, tlsConfig), nil
  1153  		},
  1154  	}
  1155  	if err := ExportHttp2ConfigureTransport(tr); err != nil {
  1156  		t.Fatal(err)
  1157  	}
  1158  	defer tr.CloseIdleConnections()
  1159  
  1160  	c := &Client{Transport: tr}
  1161  
  1162  	const N = 10
  1163  	gotBody := make(chan string, N)
  1164  	var wg sync.WaitGroup
  1165  	for i := 0; i < N; i++ {
  1166  		wg.Add(1)
  1167  		go func() {
  1168  			defer wg.Done()
  1169  			resp, err := c.Get(cst.ts.URL)
  1170  			if err != nil {
  1171  				// Try to work around spurious connection reset on loaded system.
  1172  				// See golang.org/issue/33585 and golang.org/issue/36797.
  1173  				time.Sleep(10 * time.Millisecond)
  1174  				resp, err = c.Get(cst.ts.URL)
  1175  				if err != nil {
  1176  					t.Errorf("Get: %v", err)
  1177  					return
  1178  				}
  1179  			}
  1180  			defer resp.Body.Close()
  1181  			slurp, err := io.ReadAll(resp.Body)
  1182  			if err != nil {
  1183  				t.Error(err)
  1184  			}
  1185  			gotBody <- string(slurp)
  1186  		}()
  1187  	}
  1188  	wg.Wait()
  1189  	close(gotBody)
  1190  
  1191  	var last string
  1192  	for got := range gotBody {
  1193  		if last == "" {
  1194  			last = got
  1195  			continue
  1196  		}
  1197  		if got != last {
  1198  			t.Errorf("Response body changed: %q -> %q", last, got)
  1199  		}
  1200  	}
  1201  
  1202  	var open, close int32
  1203  	for i := 0; i < 150; i++ {
  1204  		open, close = atomic.LoadInt32(&numOpen), atomic.LoadInt32(&numClose)
  1205  		if open < 1 {
  1206  			t.Fatalf("open = %d; want at least", open)
  1207  		}
  1208  		if close == open-1 {
  1209  			// Success
  1210  			return
  1211  		}
  1212  		time.Sleep(10 * time.Millisecond)
  1213  	}
  1214  	t.Errorf("%d connections opened, %d closed; want %d to close", open, close, open-1)
  1215  }
  1216  
  1217  // tests that Transport doesn't retain a pointer to the provided request.
  1218  func TestTransportGCRequest(t *testing.T) {
  1219  	run(t, func(t *testing.T, mode testMode) {
  1220  		t.Run("Body", func(t *testing.T) { testTransportGCRequest(t, mode, true) })
  1221  		t.Run("NoBody", func(t *testing.T) { testTransportGCRequest(t, mode, false) })
  1222  	})
  1223  }
  1224  func testTransportGCRequest(t *testing.T, mode testMode, body bool) {
  1225  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1226  		io.ReadAll(r.Body)
  1227  		if body {
  1228  			io.WriteString(w, "Hello.")
  1229  		}
  1230  	}))
  1231  
  1232  	didGC := make(chan struct{})
  1233  	(func() {
  1234  		body := strings.NewReader("some body")
  1235  		req, _ := NewRequest("POST", cst.ts.URL, body)
  1236  		runtime.AddCleanup(req, func(ch chan struct{}) { close(ch) }, didGC)
  1237  		res, err := cst.c.Do(req)
  1238  		if err != nil {
  1239  			t.Fatal(err)
  1240  		}
  1241  		if _, err := io.ReadAll(res.Body); err != nil {
  1242  			t.Fatal(err)
  1243  		}
  1244  		if err := res.Body.Close(); err != nil {
  1245  			t.Fatal(err)
  1246  		}
  1247  	})()
  1248  	for {
  1249  		select {
  1250  		case <-didGC:
  1251  			return
  1252  		case <-time.After(1 * time.Millisecond):
  1253  			runtime.GC()
  1254  		}
  1255  	}
  1256  }
  1257  
  1258  func TestTransportRejectsInvalidHeaders(t *testing.T) { run(t, testTransportRejectsInvalidHeaders) }
  1259  func testTransportRejectsInvalidHeaders(t *testing.T, mode testMode) {
  1260  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1261  		fmt.Fprintf(w, "Handler saw headers: %q", r.Header)
  1262  	}), optQuietLog)
  1263  	cst.tr.DisableKeepAlives = true
  1264  
  1265  	tests := []struct {
  1266  		key, val string
  1267  		ok       bool
  1268  	}{
  1269  		{"Foo", "capital-key", true}, // verify h2 allows capital keys
  1270  		{"Foo", "foo\x00bar", false}, // \x00 byte in value not allowed
  1271  		{"Foo", "two\nlines", false}, // \n byte in value not allowed
  1272  		{"bogus\nkey", "v", false},   // \n byte also not allowed in key
  1273  		{"A space", "v", false},      // spaces in keys not allowed
  1274  		{"имя", "v", false},          // key must be ascii
  1275  		{"name", "валю", true},       // value may be non-ascii
  1276  		{"", "v", false},             // key must be non-empty
  1277  		{"k", "", true},              // value may be empty
  1278  	}
  1279  	for _, tt := range tests {
  1280  		dialedc := make(chan bool, 1)
  1281  		cst.tr.Dial = func(netw, addr string) (net.Conn, error) {
  1282  			dialedc <- true
  1283  			return net.Dial(netw, addr)
  1284  		}
  1285  		req, _ := NewRequest("GET", cst.ts.URL, nil)
  1286  		req.Header[tt.key] = []string{tt.val}
  1287  		res, err := cst.c.Do(req)
  1288  		var body []byte
  1289  		if err == nil {
  1290  			body, _ = io.ReadAll(res.Body)
  1291  			res.Body.Close()
  1292  		}
  1293  		var dialed bool
  1294  		select {
  1295  		case <-dialedc:
  1296  			dialed = true
  1297  		default:
  1298  		}
  1299  
  1300  		if !tt.ok && dialed {
  1301  			t.Errorf("For key %q, value %q, transport dialed. Expected local failure. Response was: (%v, %v)\nServer replied with: %s", tt.key, tt.val, res, err, body)
  1302  		} else if (err == nil) != tt.ok {
  1303  			t.Errorf("For key %q, value %q; got err = %v; want ok=%v", tt.key, tt.val, err, tt.ok)
  1304  		}
  1305  	}
  1306  }
  1307  
  1308  func TestInterruptWithPanic(t *testing.T) {
  1309  	run(t, func(t *testing.T, mode testMode) {
  1310  		t.Run("boom", func(t *testing.T) { testInterruptWithPanic(t, mode, "boom") })
  1311  		t.Run("nil", func(t *testing.T) { t.Setenv("GODEBUG", "panicnil=1"); testInterruptWithPanic(t, mode, nil) })
  1312  		t.Run("ErrAbortHandler", func(t *testing.T) { testInterruptWithPanic(t, mode, ErrAbortHandler) })
  1313  	}, testNotParallel)
  1314  }
  1315  func testInterruptWithPanic(t *testing.T, mode testMode, panicValue any) {
  1316  	const msg = "hello"
  1317  
  1318  	testDone := make(chan struct{})
  1319  	defer close(testDone)
  1320  
  1321  	var errorLog lockedBytesBuffer
  1322  	gotHeaders := make(chan bool, 1)
  1323  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1324  		io.WriteString(w, msg)
  1325  		w.(Flusher).Flush()
  1326  
  1327  		select {
  1328  		case <-gotHeaders:
  1329  		case <-testDone:
  1330  		}
  1331  		panic(panicValue)
  1332  	}), func(ts *httptest.Server) {
  1333  		ts.Config.ErrorLog = log.New(&errorLog, "", 0)
  1334  	})
  1335  	res, err := cst.c.Get(cst.ts.URL)
  1336  	if err != nil {
  1337  		t.Fatal(err)
  1338  	}
  1339  	gotHeaders <- true
  1340  	defer res.Body.Close()
  1341  	slurp, err := io.ReadAll(res.Body)
  1342  	if string(slurp) != msg {
  1343  		t.Errorf("client read %q; want %q", slurp, msg)
  1344  	}
  1345  	if err == nil {
  1346  		t.Errorf("client read all successfully; want some error")
  1347  	}
  1348  	logOutput := func() string {
  1349  		errorLog.Lock()
  1350  		defer errorLog.Unlock()
  1351  		return errorLog.String()
  1352  	}
  1353  	wantStackLogged := panicValue != nil && panicValue != ErrAbortHandler
  1354  
  1355  	waitCondition(t, 10*time.Millisecond, func(d time.Duration) bool {
  1356  		gotLog := logOutput()
  1357  		if !wantStackLogged {
  1358  			if gotLog == "" {
  1359  				return true
  1360  			}
  1361  			t.Fatalf("want no log output; got: %s", gotLog)
  1362  		}
  1363  		if gotLog == "" {
  1364  			if d > 0 {
  1365  				t.Logf("wanted a stack trace logged; got nothing after %v", d)
  1366  			}
  1367  			return false
  1368  		}
  1369  		if !strings.Contains(gotLog, "created by ") && strings.Count(gotLog, "\n") < 6 {
  1370  			if d > 0 {
  1371  				t.Logf("output doesn't look like a panic stack trace after %v. Got: %s", d, gotLog)
  1372  			}
  1373  			return false
  1374  		}
  1375  		return true
  1376  	})
  1377  }
  1378  
  1379  type lockedBytesBuffer struct {
  1380  	sync.Mutex
  1381  	bytes.Buffer
  1382  }
  1383  
  1384  func (b *lockedBytesBuffer) Write(p []byte) (int, error) {
  1385  	b.Lock()
  1386  	defer b.Unlock()
  1387  	return b.Buffer.Write(p)
  1388  }
  1389  
  1390  // Issue 15366
  1391  func TestH12_AutoGzipWithDumpResponse(t *testing.T) {
  1392  	h12Compare{
  1393  		Handler: func(w ResponseWriter, r *Request) {
  1394  			h := w.Header()
  1395  			h.Set("Content-Encoding", "gzip")
  1396  			h.Set("Content-Length", "23")
  1397  			io.WriteString(w, "\x1f\x8b\b\x00\x00\x00\x00\x00\x00\x00s\xf3\xf7\a\x00\xab'\xd4\x1a\x03\x00\x00\x00")
  1398  		},
  1399  		EarlyCheckResponse: func(proto string, res *Response) {
  1400  			if !res.Uncompressed {
  1401  				t.Errorf("%s: expected Uncompressed to be set", proto)
  1402  			}
  1403  			dump, err := httputil.DumpResponse(res, true)
  1404  			if err != nil {
  1405  				t.Errorf("%s: DumpResponse: %v", proto, err)
  1406  				return
  1407  			}
  1408  			if strings.Contains(string(dump), "Connection: close") {
  1409  				t.Errorf("%s: should not see \"Connection: close\" in dump; got:\n%s", proto, dump)
  1410  			}
  1411  			if !strings.Contains(string(dump), "FOO") {
  1412  				t.Errorf("%s: should see \"FOO\" in response; got:\n%s", proto, dump)
  1413  			}
  1414  		},
  1415  	}.run(t)
  1416  }
  1417  
  1418  // Issue 14607
  1419  func TestCloseIdleConnections(t *testing.T) { run(t, testCloseIdleConnections) }
  1420  func testCloseIdleConnections(t *testing.T, mode testMode) {
  1421  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1422  		w.Header().Set("X-Addr", r.RemoteAddr)
  1423  	}))
  1424  	get := func() string {
  1425  		res, err := cst.c.Get(cst.ts.URL)
  1426  		if err != nil {
  1427  			t.Fatal(err)
  1428  		}
  1429  		res.Body.Close()
  1430  		v := res.Header.Get("X-Addr")
  1431  		if v == "" {
  1432  			t.Fatal("didn't get X-Addr")
  1433  		}
  1434  		return v
  1435  	}
  1436  	a1 := get()
  1437  	cst.tr.CloseIdleConnections()
  1438  	a2 := get()
  1439  	if a1 == a2 {
  1440  		t.Errorf("didn't close connection")
  1441  	}
  1442  }
  1443  
  1444  type noteCloseConn struct {
  1445  	net.Conn
  1446  	closeFunc func()
  1447  }
  1448  
  1449  func (x noteCloseConn) Close() error {
  1450  	x.closeFunc()
  1451  	return x.Conn.Close()
  1452  }
  1453  
  1454  type testErrorReader struct{ t *testing.T }
  1455  
  1456  func (r testErrorReader) Read(p []byte) (n int, err error) {
  1457  	r.t.Error("unexpected Read call")
  1458  	return 0, io.EOF
  1459  }
  1460  
  1461  func TestNoSniffExpectRequestBody(t *testing.T) { run(t, testNoSniffExpectRequestBody) }
  1462  func testNoSniffExpectRequestBody(t *testing.T, mode testMode) {
  1463  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1464  		w.WriteHeader(StatusUnauthorized)
  1465  	}))
  1466  
  1467  	// Set ExpectContinueTimeout non-zero so RoundTrip won't try to write it.
  1468  	cst.tr.ExpectContinueTimeout = 10 * time.Second
  1469  
  1470  	req, err := NewRequest("POST", cst.ts.URL, testErrorReader{t})
  1471  	if err != nil {
  1472  		t.Fatal(err)
  1473  	}
  1474  	req.ContentLength = 0 // so transport is tempted to sniff it
  1475  	req.Header.Set("Expect", "100-continue")
  1476  	res, err := cst.tr.RoundTrip(req)
  1477  	if err != nil {
  1478  		t.Fatal(err)
  1479  	}
  1480  	defer res.Body.Close()
  1481  	if res.StatusCode != StatusUnauthorized {
  1482  		t.Errorf("status code = %v; want %v", res.StatusCode, StatusUnauthorized)
  1483  	}
  1484  }
  1485  
  1486  func TestServerUndeclaredTrailers(t *testing.T) { run(t, testServerUndeclaredTrailers) }
  1487  func testServerUndeclaredTrailers(t *testing.T, mode testMode) {
  1488  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1489  		w.Header().Set("Foo", "Bar")
  1490  		w.Header().Set("Trailer:Foo", "Baz")
  1491  		w.(Flusher).Flush()
  1492  		w.Header().Add("Trailer:Foo", "Baz2")
  1493  		w.Header().Set("Trailer:Bar", "Quux")
  1494  	}))
  1495  	res, err := cst.c.Get(cst.ts.URL)
  1496  	if err != nil {
  1497  		t.Fatal(err)
  1498  	}
  1499  	if _, err := io.Copy(io.Discard, res.Body); err != nil {
  1500  		t.Fatal(err)
  1501  	}
  1502  	res.Body.Close()
  1503  	delete(res.Header, "Date")
  1504  	delete(res.Header, "Content-Type")
  1505  
  1506  	if want := (Header{"Foo": {"Bar"}}); !reflect.DeepEqual(res.Header, want) {
  1507  		t.Errorf("Header = %#v; want %#v", res.Header, want)
  1508  	}
  1509  	if want := (Header{"Foo": {"Baz", "Baz2"}, "Bar": {"Quux"}}); !reflect.DeepEqual(res.Trailer, want) {
  1510  		t.Errorf("Trailer = %#v; want %#v", res.Trailer, want)
  1511  	}
  1512  }
  1513  
  1514  func TestBadResponseAfterReadingBody(t *testing.T) {
  1515  	run(t, testBadResponseAfterReadingBody, []testMode{http1Mode})
  1516  }
  1517  func testBadResponseAfterReadingBody(t *testing.T, mode testMode) {
  1518  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1519  		_, err := io.Copy(io.Discard, r.Body)
  1520  		if err != nil {
  1521  			t.Fatal(err)
  1522  		}
  1523  		c, _, err := w.(Hijacker).Hijack()
  1524  		if err != nil {
  1525  			t.Fatal(err)
  1526  		}
  1527  		defer c.Close()
  1528  		fmt.Fprintln(c, "some bogus crap")
  1529  	}))
  1530  
  1531  	closes := 0
  1532  	res, err := cst.c.Post(cst.ts.URL, "text/plain", countCloseReader{&closes, strings.NewReader("hello")})
  1533  	if err == nil {
  1534  		res.Body.Close()
  1535  		t.Fatal("expected an error to be returned from Post")
  1536  	}
  1537  	if closes != 1 {
  1538  		t.Errorf("closes = %d; want 1", closes)
  1539  	}
  1540  }
  1541  
  1542  func TestWriteHeader0(t *testing.T) { run(t, testWriteHeader0) }
  1543  func testWriteHeader0(t *testing.T, mode testMode) {
  1544  	gotpanic := make(chan bool, 1)
  1545  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1546  		defer close(gotpanic)
  1547  		defer func() {
  1548  			if e := recover(); e != nil {
  1549  				got := fmt.Sprintf("%T, %v", e, e)
  1550  				want := "string, invalid WriteHeader code 0"
  1551  				if got != want {
  1552  					t.Errorf("unexpected panic value:\n got: %v\nwant: %v\n", got, want)
  1553  				}
  1554  				gotpanic <- true
  1555  
  1556  				// Set an explicit 503. This also tests that the WriteHeader call panics
  1557  				// before it recorded that an explicit value was set and that bogus
  1558  				// value wasn't stuck.
  1559  				w.WriteHeader(503)
  1560  			}
  1561  		}()
  1562  		w.WriteHeader(0)
  1563  	}))
  1564  	res, err := cst.c.Get(cst.ts.URL)
  1565  	if err != nil {
  1566  		t.Fatal(err)
  1567  	}
  1568  	if res.StatusCode != 503 {
  1569  		t.Errorf("Response: %v %q; want 503", res.StatusCode, res.Status)
  1570  	}
  1571  	if !<-gotpanic {
  1572  		t.Error("expected panic in handler")
  1573  	}
  1574  }
  1575  
  1576  // Issue 23010: don't be super strict checking WriteHeader's code if
  1577  // it's not even valid to call WriteHeader then anyway.
  1578  func TestWriteHeaderNoCodeCheck(t *testing.T) {
  1579  	run(t, func(t *testing.T, mode testMode) {
  1580  		testWriteHeaderAfterWrite(t, mode, false)
  1581  	})
  1582  }
  1583  func TestWriteHeaderNoCodeCheck_h1hijack(t *testing.T) {
  1584  	testWriteHeaderAfterWrite(t, http1Mode, true)
  1585  }
  1586  func testWriteHeaderAfterWrite(t *testing.T, mode testMode, hijack bool) {
  1587  	var errorLog lockedBytesBuffer
  1588  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1589  		if hijack {
  1590  			conn, _, _ := w.(Hijacker).Hijack()
  1591  			defer conn.Close()
  1592  			conn.Write([]byte("HTTP/1.1 200 OK\r\nContent-Length: 6\r\n\r\nfoo"))
  1593  			w.WriteHeader(0) // verify this doesn't panic if there's already output; Issue 23010
  1594  			conn.Write([]byte("bar"))
  1595  			return
  1596  		}
  1597  		io.WriteString(w, "foo")
  1598  		w.(Flusher).Flush()
  1599  		w.WriteHeader(0) // verify this doesn't panic if there's already output; Issue 23010
  1600  		io.WriteString(w, "bar")
  1601  	}), func(ts *httptest.Server) {
  1602  		ts.Config.ErrorLog = log.New(&errorLog, "", 0)
  1603  	})
  1604  	res, err := cst.c.Get(cst.ts.URL)
  1605  	if err != nil {
  1606  		t.Fatal(err)
  1607  	}
  1608  	defer res.Body.Close()
  1609  	body, err := io.ReadAll(res.Body)
  1610  	if err != nil {
  1611  		t.Fatal(err)
  1612  	}
  1613  	if got, want := string(body), "foobar"; got != want {
  1614  		t.Errorf("got = %q; want %q", got, want)
  1615  	}
  1616  
  1617  	// Also check the stderr output:
  1618  	if mode == http2Mode {
  1619  		// TODO: also emit this log message for HTTP/2?
  1620  		// We historically haven't, so don't check.
  1621  		return
  1622  	}
  1623  	gotLog := strings.TrimSpace(errorLog.String())
  1624  	wantLog := "http: superfluous response.WriteHeader call from net/http_test.testWriteHeaderAfterWrite.func1 (clientserver_test.go:"
  1625  	if hijack {
  1626  		wantLog = "http: response.WriteHeader on hijacked connection from net/http_test.testWriteHeaderAfterWrite.func1 (clientserver_test.go:"
  1627  	}
  1628  	if !strings.HasPrefix(gotLog, wantLog) {
  1629  		t.Errorf("stderr output = %q; want %q", gotLog, wantLog)
  1630  	}
  1631  }
  1632  
  1633  func TestBidiStreamReverseProxy(t *testing.T) {
  1634  	run(t, testBidiStreamReverseProxy, []testMode{http2Mode})
  1635  }
  1636  func testBidiStreamReverseProxy(t *testing.T, mode testMode) {
  1637  	backend := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1638  		if _, err := io.Copy(w, r.Body); err != nil {
  1639  			log.Printf("bidi backend copy: %v", err)
  1640  		}
  1641  	}))
  1642  
  1643  	backURL, err := url.Parse(backend.ts.URL)
  1644  	if err != nil {
  1645  		t.Fatal(err)
  1646  	}
  1647  	rp := httputil.NewSingleHostReverseProxy(backURL)
  1648  	rp.Transport = backend.tr
  1649  	proxy := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1650  		rp.ServeHTTP(w, r)
  1651  	}))
  1652  
  1653  	bodyRes := make(chan any, 1) // error or hash.Hash
  1654  	pr, pw := io.Pipe()
  1655  	req, _ := NewRequest("PUT", proxy.ts.URL, pr)
  1656  	const size = 4 << 20
  1657  	go func() {
  1658  		h := sha1.New()
  1659  		_, err := io.CopyN(io.MultiWriter(h, pw), rand.Reader, size)
  1660  		go pw.Close()
  1661  		if err != nil {
  1662  			t.Errorf("body copy: %v", err)
  1663  			bodyRes <- err
  1664  		} else {
  1665  			bodyRes <- h
  1666  		}
  1667  	}()
  1668  	res, err := backend.c.Do(req)
  1669  	if err != nil {
  1670  		t.Fatal(err)
  1671  	}
  1672  	defer res.Body.Close()
  1673  	hgot := sha1.New()
  1674  	n, err := io.Copy(hgot, res.Body)
  1675  	if err != nil {
  1676  		t.Fatal(err)
  1677  	}
  1678  	if n != size {
  1679  		t.Fatalf("got %d bytes; want %d", n, size)
  1680  	}
  1681  	select {
  1682  	case v := <-bodyRes:
  1683  		switch v := v.(type) {
  1684  		default:
  1685  			t.Fatalf("body copy: %v", err)
  1686  		case hash.Hash:
  1687  			if !bytes.Equal(v.Sum(nil), hgot.Sum(nil)) {
  1688  				t.Errorf("written bytes didn't match received bytes")
  1689  			}
  1690  		}
  1691  	case <-time.After(10 * time.Second):
  1692  		t.Fatal("timeout")
  1693  	}
  1694  
  1695  }
  1696  
  1697  // Always use HTTP/1.1 for WebSocket upgrades.
  1698  func TestH12_WebSocketUpgrade(t *testing.T) {
  1699  	h12Compare{
  1700  		Handler: func(w ResponseWriter, r *Request) {
  1701  			h := w.Header()
  1702  			h.Set("Foo", "bar")
  1703  		},
  1704  		ReqFunc: func(c *Client, url string) (*Response, error) {
  1705  			req, _ := NewRequest("GET", url, nil)
  1706  			req.Header.Set("Connection", "Upgrade")
  1707  			req.Header.Set("Upgrade", "WebSocket")
  1708  			return c.Do(req)
  1709  		},
  1710  		EarlyCheckResponse: func(proto string, res *Response) {
  1711  			if res.Proto != "HTTP/1.1" {
  1712  				t.Errorf("%s: expected HTTP/1.1, got %q", proto, res.Proto)
  1713  			}
  1714  			res.Proto = "HTTP/IGNORE" // skip later checks that Proto must be 1.1 vs 2.0
  1715  		},
  1716  	}.run(t)
  1717  }
  1718  
  1719  func TestIdentityTransferEncoding(t *testing.T) { run(t, testIdentityTransferEncoding) }
  1720  func testIdentityTransferEncoding(t *testing.T, mode testMode) {
  1721  	const body = "body"
  1722  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1723  		gotBody, _ := io.ReadAll(r.Body)
  1724  		if got, want := string(gotBody), body; got != want {
  1725  			t.Errorf("got request body = %q; want %q", got, want)
  1726  		}
  1727  		w.Header().Set("Transfer-Encoding", "identity")
  1728  		w.WriteHeader(StatusOK)
  1729  		w.(Flusher).Flush()
  1730  		io.WriteString(w, body)
  1731  	}))
  1732  	req, _ := NewRequest("GET", cst.ts.URL, strings.NewReader(body))
  1733  	res, err := cst.c.Do(req)
  1734  	if err != nil {
  1735  		t.Fatal(err)
  1736  	}
  1737  	defer res.Body.Close()
  1738  	gotBody, err := io.ReadAll(res.Body)
  1739  	if err != nil {
  1740  		t.Fatal(err)
  1741  	}
  1742  	if got, want := string(gotBody), body; got != want {
  1743  		t.Errorf("got response body = %q; want %q", got, want)
  1744  	}
  1745  }
  1746  
  1747  func TestEarlyHintsRequest(t *testing.T) { run(t, testEarlyHintsRequest) }
  1748  func testEarlyHintsRequest(t *testing.T, mode testMode) {
  1749  	var wg sync.WaitGroup
  1750  	wg.Add(1)
  1751  	cst := newClientServerTest(t, mode, HandlerFunc(func(w ResponseWriter, r *Request) {
  1752  		h := w.Header()
  1753  
  1754  		h.Add("Content-Length", "123") // must be ignored
  1755  		h.Add("Link", "</style.css>; rel=preload; as=style")
  1756  		h.Add("Link", "</script.js>; rel=preload; as=script")
  1757  		w.WriteHeader(StatusEarlyHints)
  1758  
  1759  		wg.Wait()
  1760  
  1761  		h.Add("Link", "</foo.js>; rel=preload; as=script")
  1762  		w.WriteHeader(StatusEarlyHints)
  1763  
  1764  		w.Write([]byte("Hello"))
  1765  	}))
  1766  
  1767  	checkLinkHeaders := func(t *testing.T, expected, got []string) {
  1768  		t.Helper()
  1769  
  1770  		if len(expected) != len(got) {
  1771  			t.Errorf("got %d expected %d", len(got), len(expected))
  1772  		}
  1773  
  1774  		for i := range expected {
  1775  			if expected[i] != got[i] {
  1776  				t.Errorf("got %q expected %q", got[i], expected[i])
  1777  			}
  1778  		}
  1779  	}
  1780  
  1781  	checkExcludedHeaders := func(t *testing.T, header textproto.MIMEHeader) {
  1782  		t.Helper()
  1783  
  1784  		for _, h := range []string{"Content-Length", "Transfer-Encoding"} {
  1785  			if v, ok := header[h]; ok {
  1786  				t.Errorf("%s is %q; must not be sent", h, v)
  1787  			}
  1788  		}
  1789  	}
  1790  
  1791  	var respCounter uint8
  1792  	trace := &httptrace.ClientTrace{
  1793  		Got1xxResponse: func(code int, header textproto.MIMEHeader) error {
  1794  			switch respCounter {
  1795  			case 0:
  1796  				checkLinkHeaders(t, []string{"</style.css>; rel=preload; as=style", "</script.js>; rel=preload; as=script"}, header["Link"])
  1797  				checkExcludedHeaders(t, header)
  1798  
  1799  				wg.Done()
  1800  			case 1:
  1801  				checkLinkHeaders(t, []string{"</style.css>; rel=preload; as=style", "</script.js>; rel=preload; as=script", "</foo.js>; rel=preload; as=script"}, header["Link"])
  1802  				checkExcludedHeaders(t, header)
  1803  
  1804  			default:
  1805  				t.Error("Unexpected 1xx response")
  1806  			}
  1807  
  1808  			respCounter++
  1809  
  1810  			return nil
  1811  		},
  1812  	}
  1813  	req, _ := NewRequestWithContext(httptrace.WithClientTrace(context.Background(), trace), "GET", cst.ts.URL, nil)
  1814  
  1815  	res, err := cst.c.Do(req)
  1816  	if err != nil {
  1817  		t.Fatal(err)
  1818  	}
  1819  	defer res.Body.Close()
  1820  
  1821  	checkLinkHeaders(t, []string{"</style.css>; rel=preload; as=style", "</script.js>; rel=preload; as=script", "</foo.js>; rel=preload; as=script"}, res.Header["Link"])
  1822  	if cl := res.Header.Get("Content-Length"); cl != "123" {
  1823  		t.Errorf("Content-Length is %q; want 123", cl)
  1824  	}
  1825  
  1826  	body, _ := io.ReadAll(res.Body)
  1827  	if string(body) != "Hello" {
  1828  		t.Errorf("Read body %q; want Hello", body)
  1829  	}
  1830  }
  1831  

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