net/http2/transport_test.go

// Copyright 2015 The Go 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 http2

import (
	"bufio"
	"bytes"
	"crypto/tls"
	"errors"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"math/rand"
	"net"
	"net/http"
	"net/url"
	"os"
	"reflect"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"golang.org/x/net/http2/hpack"
)

var (
	extNet        = flag.Bool("extnet", false, "do external network tests")
	transportHost = flag.String("transporthost", "http2.golang.org", "hostname to use for TestTransport")
	insecure      = flag.Bool("insecure", false, "insecure TLS dials") // TODO: dead code. remove?
)

var tlsConfigInsecure = &tls.Config{InsecureSkipVerify: true}

func TestTransportExternal(t *testing.T) {
	if !*extNet {
		t.Skip("skipping external network test")
	}
	req, _ := http.NewRequest("GET", "https://"+*transportHost+"/", nil)
	rt := &Transport{TLSClientConfig: tlsConfigInsecure}
	res, err := rt.RoundTrip(req)
	if err != nil {
		t.Fatalf("%v", err)
	}
	res.Write(os.Stdout)
}

func TestTransport(t *testing.T) {
	const body = "sup"
	st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, body)
	}, optOnlyServer)
	defer st.Close()

	tr := &Transport{TLSClientConfig: tlsConfigInsecure}
	defer tr.CloseIdleConnections()

	req, err := http.NewRequest("GET", st.ts.URL, nil)
	if err != nil {
		t.Fatal(err)
	}
	res, err := tr.RoundTrip(req)
	if err != nil {
		t.Fatal(err)
	}
	defer res.Body.Close()

	t.Logf("Got res: %+v", res)
	if g, w := res.StatusCode, 200; g != w {
		t.Errorf("StatusCode = %v; want %v", g, w)
	}
	if g, w := res.Status, "200 OK"; g != w {
		t.Errorf("Status = %q; want %q", g, w)
	}
	wantHeader := http.Header{
		"Content-Length": []string{"3"},
		"Content-Type":   []string{"text/plain; charset=utf-8"},
		"Date":           []string{"XXX"}, // see cleanDate
	}
	cleanDate(res)
	if !reflect.DeepEqual(res.Header, wantHeader) {
		t.Errorf("res Header = %v; want %v", res.Header, wantHeader)
	}
	if res.Request != req {
		t.Errorf("Response.Request = %p; want %p", res.Request, req)
	}
	if res.TLS == nil {
		t.Error("Response.TLS = nil; want non-nil")
	}
	slurp, err := ioutil.ReadAll(res.Body)
	if err != nil {
		t.Errorf("Body read: %v", err)
	} else if string(slurp) != body {
		t.Errorf("Body = %q; want %q", slurp, body)
	}

}

func TestTransportReusesConns(t *testing.T) {
	st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, r.RemoteAddr)
	}, optOnlyServer)
	defer st.Close()
	tr := &Transport{TLSClientConfig: tlsConfigInsecure}
	defer tr.CloseIdleConnections()
	get := func() string {
		req, err := http.NewRequest("GET", st.ts.URL, nil)
		if err != nil {
			t.Fatal(err)
		}
		res, err := tr.RoundTrip(req)
		if err != nil {
			t.Fatal(err)
		}
		defer res.Body.Close()
		slurp, err := ioutil.ReadAll(res.Body)
		if err != nil {
			t.Fatalf("Body read: %v", err)
		}
		addr := strings.TrimSpace(string(slurp))
		if addr == "" {
			t.Fatalf("didn't get an addr in response")
		}
		return addr
	}
	first := get()
	second := get()
	if first != second {
		t.Errorf("first and second responses were on different connections: %q vs %q", first, second)
	}
}

// Tests that the Transport only keeps one pending dial open per destination address.
// https://golang.org/issue/13397
func TestTransportGroupsPendingDials(t *testing.T) {
	st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, r.RemoteAddr)
	}, optOnlyServer)
	defer st.Close()
	tr := &Transport{
		TLSClientConfig: tlsConfigInsecure,
	}
	defer tr.CloseIdleConnections()
	var (
		mu    sync.Mutex
		dials = map[string]int{}
	)
	var wg sync.WaitGroup
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			req, err := http.NewRequest("GET", st.ts.URL, nil)
			if err != nil {
				t.Error(err)
				return
			}
			res, err := tr.RoundTrip(req)
			if err != nil {
				t.Error(err)
				return
			}
			defer res.Body.Close()
			slurp, err := ioutil.ReadAll(res.Body)
			if err != nil {
				t.Errorf("Body read: %v", err)
			}
			addr := strings.TrimSpace(string(slurp))
			if addr == "" {
				t.Errorf("didn't get an addr in response")
			}
			mu.Lock()
			dials[addr]++
			mu.Unlock()
		}()
	}
	wg.Wait()
	if len(dials) != 1 {
		t.Errorf("saw %d dials; want 1: %v", len(dials), dials)
	}
	tr.CloseIdleConnections()
	if err := retry(50, 10*time.Millisecond, func() error {
		cp, ok := tr.connPool().(*clientConnPool)
		if !ok {
			return fmt.Errorf("Conn pool is %T; want *clientConnPool", tr.connPool())
		}
		cp.mu.Lock()
		defer cp.mu.Unlock()
		if len(cp.dialing) != 0 {
			return fmt.Errorf("dialing map = %v; want empty", cp.dialing)
		}
		if len(cp.conns) != 0 {
			return fmt.Errorf("conns = %v; want empty", cp.conns)
		}
		if len(cp.keys) != 0 {
			return fmt.Errorf("keys = %v; want empty", cp.keys)
		}
		return nil
	}); err != nil {
		t.Errorf("State of pool after CloseIdleConnections: %v", err)
	}
}

func retry(tries int, delay time.Duration, fn func() error) error {
	var err error
	for i := 0; i < tries; i++ {
		err = fn()
		if err == nil {
			return nil
		}
		time.Sleep(delay)
	}
	return err
}

func TestTransportAbortClosesPipes(t *testing.T) {
	shutdown := make(chan struct{})
	st := newServerTester(t,
		func(w http.ResponseWriter, r *http.Request) {
			w.(http.Flusher).Flush()
			<-shutdown
		},
		optOnlyServer,
	)
	defer st.Close()
	defer close(shutdown) // we must shutdown before st.Close() to avoid hanging

	done := make(chan struct{})
	requestMade := make(chan struct{})
	go func() {
		defer close(done)
		tr := &Transport{TLSClientConfig: tlsConfigInsecure}
		req, err := http.NewRequest("GET", st.ts.URL, nil)
		if err != nil {
			t.Fatal(err)
		}
		res, err := tr.RoundTrip(req)
		if err != nil {
			t.Fatal(err)
		}
		defer res.Body.Close()
		close(requestMade)
		_, err = ioutil.ReadAll(res.Body)
		if err == nil {
			t.Error("expected error from res.Body.Read")
		}
	}()

	<-requestMade
	// Now force the serve loop to end, via closing the connection.
	st.closeConn()
	// deadlock? that's a bug.
	select {
	case <-done:
	case <-time.After(3 * time.Second):
		t.Fatal("timeout")
	}
}

// TODO: merge this with TestTransportBody to make TestTransportRequest? This
// could be a table-driven test with extra goodies.
func TestTransportPath(t *testing.T) {
	gotc := make(chan *url.URL, 1)
	st := newServerTester(t,
		func(w http.ResponseWriter, r *http.Request) {
			gotc <- r.URL
		},
		optOnlyServer,
	)
	defer st.Close()

	tr := &Transport{TLSClientConfig: tlsConfigInsecure}
	defer tr.CloseIdleConnections()
	const (
		path  = "/testpath"
		query = "q=1"
	)
	surl := st.ts.URL + path + "?" + query
	req, err := http.NewRequest("POST", surl, nil)
	if err != nil {
		t.Fatal(err)
	}
	c := &http.Client{Transport: tr}
	res, err := c.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer res.Body.Close()
	got := <-gotc
	if got.Path != path {
		t.Errorf("Read Path = %q; want %q", got.Path, path)
	}
	if got.RawQuery != query {
		t.Errorf("Read RawQuery = %q; want %q", got.RawQuery, query)
	}
}

func randString(n int) string {
	rnd := rand.New(rand.NewSource(int64(n)))
	b := make([]byte, n)
	for i := range b {
		b[i] = byte(rnd.Intn(256))
	}
	return string(b)
}

var bodyTests = []struct {
	body         string
	noContentLen bool
}{
	{body: "some message"},
	{body: "some message", noContentLen: true},
	{body: ""},
	{body: "", noContentLen: true},
	{body: strings.Repeat("a", 1<<20), noContentLen: true},
	{body: strings.Repeat("a", 1<<20)},
	{body: randString(16<<10 - 1)},
	{body: randString(16 << 10)},
	{body: randString(16<<10 + 1)},
	{body: randString(512<<10 - 1)},
	{body: randString(512 << 10)},
	{body: randString(512<<10 + 1)},
	{body: randString(1<<20 - 1)},
	{body: randString(1 << 20)},
	{body: randString(1<<20 + 2)},
}

func TestTransportBody(t *testing.T) {
	gotc := make(chan interface{}, 1)
	st := newServerTester(t,
		func(w http.ResponseWriter, r *http.Request) {
			slurp, err := ioutil.ReadAll(r.Body)
			if err != nil {
				gotc <- err
			} else {
				gotc <- string(slurp)
			}
		},
		optOnlyServer,
	)
	defer st.Close()

	for i, tt := range bodyTests {
		tr := &Transport{TLSClientConfig: tlsConfigInsecure}
		defer tr.CloseIdleConnections()

		var body io.Reader = strings.NewReader(tt.body)
		if tt.noContentLen {
			body = struct{ io.Reader }{body} // just a Reader, hiding concrete type and other methods
		}
		req, err := http.NewRequest("POST", st.ts.URL, body)
		if err != nil {
			t.Fatalf("#%d: %v", i, err)
		}
		c := &http.Client{Transport: tr}
		res, err := c.Do(req)
		if err != nil {
			t.Fatalf("#%d: %v", i, err)
		}
		defer res.Body.Close()
		got := <-gotc
		if err, ok := got.(error); ok {
			t.Fatalf("#%d: %v", i, err)
		} else if got.(string) != tt.body {
			got := got.(string)
			t.Errorf("#%d: Read body mismatch.\n got: %q (len %d)\nwant: %q (len %d)", i, shortString(got), len(got), shortString(tt.body), len(tt.body))
		}
	}
}

func shortString(v string) string {
	const maxLen = 100
	if len(v) <= maxLen {
		return v
	}
	return fmt.Sprintf("%v[...%d bytes omitted...]%v", v[:maxLen/2], len(v)-maxLen, v[len(v)-maxLen/2:])
}

func TestTransportDialTLS(t *testing.T) {
	var mu sync.Mutex // guards following
	var gotReq, didDial bool

	ts := newServerTester(t,
		func(w http.ResponseWriter, r *http.Request) {
			mu.Lock()
			gotReq = true
			mu.Unlock()
		},
		optOnlyServer,
	)
	defer ts.Close()
	tr := &Transport{
		DialTLS: func(netw, addr string, cfg *tls.Config) (net.Conn, error) {
			mu.Lock()
			didDial = true
			mu.Unlock()
			cfg.InsecureSkipVerify = true
			c, err := tls.Dial(netw, addr, cfg)
			if err != nil {
				return nil, err
			}
			return c, c.Handshake()
		},
	}
	defer tr.CloseIdleConnections()
	client := &http.Client{Transport: tr}
	res, err := client.Get(ts.ts.URL)
	if err != nil {
		t.Fatal(err)
	}
	res.Body.Close()
	mu.Lock()
	if !gotReq {
		t.Error("didn't get request")
	}
	if !didDial {
		t.Error("didn't use dial hook")
	}
}

func TestConfigureTransport(t *testing.T) {
	t1 := &http.Transport{}
	err := ConfigureTransport(t1)
	if err == errTransportVersion {
		t.Skip(err)
	}
	if err != nil {
		t.Fatal(err)
	}
	if got := fmt.Sprintf("%#v", *t1); !strings.Contains(got, `"h2"`) {
		// Laziness, to avoid buildtags.
		t.Errorf("stringification of HTTP/1 transport didn't contain \"h2\": %v", got)
	}
	wantNextProtos := []string{"h2", "http/1.1"}
	if t1.TLSClientConfig == nil {
		t.Errorf("nil t1.TLSClientConfig")
	} else if !reflect.DeepEqual(t1.TLSClientConfig.NextProtos, wantNextProtos) {
		t.Errorf("TLSClientConfig.NextProtos = %q; want %q", t1.TLSClientConfig.NextProtos, wantNextProtos)
	}
	if err := ConfigureTransport(t1); err == nil {
		t.Error("unexpected success on second call to ConfigureTransport")
	}

	// And does it work?
	st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, r.Proto)
	}, optOnlyServer)
	defer st.Close()

	t1.TLSClientConfig.InsecureSkipVerify = true
	c := &http.Client{Transport: t1}
	res, err := c.Get(st.ts.URL)
	if err != nil {
		t.Fatal(err)
	}
	slurp, err := ioutil.ReadAll(res.Body)
	if err != nil {
		t.Fatal(err)
	}
	if got, want := string(slurp), "HTTP/2.0"; got != want {
		t.Errorf("body = %q; want %q", got, want)
	}
}

type capitalizeReader struct {
	r io.Reader
}

func (cr capitalizeReader) Read(p []byte) (n int, err error) {
	n, err = cr.r.Read(p)
	for i, b := range p[:n] {
		if b >= 'a' && b <= 'z' {
			p[i] = b - ('a' - 'A')
		}
	}
	return
}

type flushWriter struct {
	w io.Writer
}

func (fw flushWriter) Write(p []byte) (n int, err error) {
	n, err = fw.w.Write(p)
	if f, ok := fw.w.(http.Flusher); ok {
		f.Flush()
	}
	return
}

type clientTester struct {
	t      *testing.T
	tr     *Transport
	sc, cc net.Conn // server and client conn
	fr     *Framer  // server's framer
	client func() error
	server func() error
}

func newClientTester(t *testing.T) *clientTester {
	var dialOnce struct {
		sync.Mutex
		dialed bool
	}
	ct := &clientTester{
		t: t,
	}
	ct.tr = &Transport{
		TLSClientConfig: tlsConfigInsecure,
		DialTLS: func(network, addr string, cfg *tls.Config) (net.Conn, error) {
			dialOnce.Lock()
			defer dialOnce.Unlock()
			if dialOnce.dialed {
				return nil, errors.New("only one dial allowed in test mode")
			}
			dialOnce.dialed = true
			return ct.cc, nil
		},
	}

	ln := newLocalListener(t)
	cc, err := net.Dial("tcp", ln.Addr().String())
	if err != nil {
		t.Fatal(err)

	}
	sc, err := ln.Accept()
	if err != nil {
		t.Fatal(err)
	}
	ln.Close()
	ct.cc = cc
	ct.sc = sc
	ct.fr = NewFramer(sc, sc)
	return ct
}

func newLocalListener(t *testing.T) net.Listener {
	ln, err := net.Listen("tcp4", "127.0.0.1:0")
	if err == nil {
		return ln
	}
	ln, err = net.Listen("tcp6", "[::1]:0")
	if err != nil {
		t.Fatal(err)
	}
	return ln
}

func (ct *clientTester) greet() {
	buf := make([]byte, len(ClientPreface))
	_, err := io.ReadFull(ct.sc, buf)
	if err != nil {
		ct.t.Fatalf("reading client preface: %v", err)
	}
	f, err := ct.fr.ReadFrame()
	if err != nil {
		ct.t.Fatalf("Reading client settings frame: %v", err)
	}
	if sf, ok := f.(*SettingsFrame); !ok {
		ct.t.Fatalf("Wanted client settings frame; got %v", f)
		_ = sf // stash it away?
	}
	if err := ct.fr.WriteSettings(); err != nil {
		ct.t.Fatal(err)
	}
	if err := ct.fr.WriteSettingsAck(); err != nil {
		ct.t.Fatal(err)
	}
}

func (ct *clientTester) cleanup() {
	ct.tr.CloseIdleConnections()
}

func (ct *clientTester) run() {
	errc := make(chan error, 2)
	ct.start("client", errc, ct.client)
	ct.start("server", errc, ct.server)
	defer ct.cleanup()
	for i := 0; i < 2; i++ {
		if err := <-errc; err != nil {
			ct.t.Error(err)
			return
		}
	}
}

func (ct *clientTester) start(which string, errc chan<- error, fn func() error) {
	go func() {
		finished := false
		var err error
		defer func() {
			if !finished {
				err = fmt.Errorf("%s goroutine didn't finish.", which)
			} else if err != nil {
				err = fmt.Errorf("%s: %v", which, err)
			}
			errc <- err
		}()
		err = fn()
		finished = true
	}()
}

type countingReader struct {
	n *int64
}

func (r countingReader) Read(p []byte) (n int, err error) {
	for i := range p {
		p[i] = byte(i)
	}
	atomic.AddInt64(r.n, int64(len(p)))
	return len(p), err
}

func TestTransportReqBodyAfterResponse_200(t *testing.T) { testTransportReqBodyAfterResponse(t, 200) }
func TestTransportReqBodyAfterResponse_403(t *testing.T) { testTransportReqBodyAfterResponse(t, 403) }

func testTransportReqBodyAfterResponse(t *testing.T, status int) {
	const bodySize = 10 << 20
	ct := newClientTester(t)
	ct.client = func() error {
		var n int64 // atomic
		req, err := http.NewRequest("PUT", "https://dummy.tld/", io.LimitReader(countingReader{&n}, bodySize))
		if err != nil {
			return err
		}
		res, err := ct.tr.RoundTrip(req)
		if err != nil {
			return fmt.Errorf("RoundTrip: %v", err)
		}
		defer res.Body.Close()
		if res.StatusCode != status {
			return fmt.Errorf("status code = %v; want %v", res.StatusCode, status)
		}
		slurp, err := ioutil.ReadAll(res.Body)
		if err != nil {
			return fmt.Errorf("Slurp: %v", err)
		}
		if len(slurp) > 0 {
			return fmt.Errorf("unexpected body: %q", slurp)
		}
		if status == 200 {
			if got := atomic.LoadInt64(&n); got != bodySize {
				return fmt.Errorf("For 200 response, Transport wrote %d bytes; want %d", got, bodySize)
			}
		} else {
			if got := atomic.LoadInt64(&n); got == 0 || got >= bodySize {
				return fmt.Errorf("For %d response, Transport wrote %d bytes; want (0,%d) exclusive", status, got, bodySize)
			}
		}
		return nil
	}
	ct.server = func() error {
		ct.greet()
		var buf bytes.Buffer
		enc := hpack.NewEncoder(&buf)
		var dataRecv int64
		var closed bool
		for {
			f, err := ct.fr.ReadFrame()
			if err != nil {
				return err
			}
			//println(fmt.Sprintf("server got frame: %v", f))
			switch f := f.(type) {
			case *WindowUpdateFrame, *SettingsFrame:
			case *HeadersFrame:
				if !f.HeadersEnded() {
					return fmt.Errorf("headers should have END_HEADERS be ended: %v", f)
				}
				if f.StreamEnded() {
					return fmt.Errorf("headers contains END_STREAM unexpectedly: %v", f)
				}
				time.Sleep(50 * time.Millisecond) // let client send body
				enc.WriteField(hpack.HeaderField{Name: ":status", Value: strconv.Itoa(status)})
				ct.fr.WriteHeaders(HeadersFrameParam{
					StreamID:      f.StreamID,
					EndHeaders:    true,
					EndStream:     false,
					BlockFragment: buf.Bytes(),
				})
			case *DataFrame:
				dataLen := len(f.Data())
				dataRecv += int64(dataLen)
				if dataLen > 0 {
					if err := ct.fr.WriteWindowUpdate(0, uint32(dataLen)); err != nil {
						return err
					}
					if err := ct.fr.WriteWindowUpdate(f.StreamID, uint32(dataLen)); err != nil {
						return err
					}
				}
				if !closed && ((status != 200 && dataRecv > 0) ||
					(status == 200 && dataRecv == bodySize)) {
					closed = true
					if err := ct.fr.WriteData(f.StreamID, true, nil); err != nil {
						return err
					}
					return nil
				}
			default:
				return fmt.Errorf("Unexpected client frame %v", f)
			}
		}
		return nil
	}
	ct.run()
}

// See golang.org/issue/13444
func TestTransportFullDuplex(t *testing.T) {
	st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(200) // redundant but for clarity
		w.(http.Flusher).Flush()
		io.Copy(flushWriter{w}, capitalizeReader{r.Body})
		fmt.Fprintf(w, "bye.\n")
	}, optOnlyServer)
	defer st.Close()

	tr := &Transport{TLSClientConfig: tlsConfigInsecure}
	defer tr.CloseIdleConnections()
	c := &http.Client{Transport: tr}

	pr, pw := io.Pipe()
	req, err := http.NewRequest("PUT", st.ts.URL, ioutil.NopCloser(pr))
	if err != nil {
		log.Fatal(err)
	}
	res, err := c.Do(req)
	if err != nil {
		log.Fatal(err)
	}
	defer res.Body.Close()
	if res.StatusCode != 200 {
		t.Fatalf("StatusCode = %v; want %v", res.StatusCode, 200)
	}
	bs := bufio.NewScanner(res.Body)
	want := func(v string) {
		if !bs.Scan() {
			t.Fatalf("wanted to read %q but Scan() = false, err = %v", v, bs.Err())
		}
	}
	write := func(v string) {
		_, err := io.WriteString(pw, v)
		if err != nil {
			t.Fatalf("pipe write: %v", err)
		}
	}
	write("foo\n")
	want("FOO")
	write("bar\n")
	want("BAR")
	pw.Close()
	want("bye.")
	if err := bs.Err(); err != nil {
		t.Fatal(err)
	}
}

func TestTransportConnectRequest(t *testing.T) {
	gotc := make(chan *http.Request, 1)
	st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
		gotc <- r
	}, optOnlyServer)
	defer st.Close()

	u, err := url.Parse(st.ts.URL)
	if err != nil {
		t.Fatal(err)
	}

	tr := &Transport{TLSClientConfig: tlsConfigInsecure}
	defer tr.CloseIdleConnections()
	c := &http.Client{Transport: tr}

	tests := []struct {
		req  *http.Request
		want string
	}{
		{
			req: &http.Request{
				Method: "CONNECT",
				Header: http.Header{},
				URL:    u,
			},
			want: u.Host,
		},
		{
			req: &http.Request{
				Method: "CONNECT",
				Header: http.Header{},
				URL:    u,
				Host:   "example.com:123",
			},
			want: "example.com:123",
		},
	}

	for i, tt := range tests {
		res, err := c.Do(tt.req)
		if err != nil {
			t.Errorf("%d. RoundTrip = %v", i, err)
			continue
		}
		res.Body.Close()
		req := <-gotc
		if req.Method != "CONNECT" {
			t.Errorf("method = %q; want CONNECT", req.Method)
		}
		if req.Host != tt.want {
			t.Errorf("Host = %q; want %q", req.Host, tt.want)
		}
		if req.URL.Host != tt.want {
			t.Errorf("URL.Host = %q; want %q", req.URL.Host, tt.want)
		}
	}
}

type headerType int

const (
	noHeader headerType = iota // omitted
	oneHeader
	splitHeader // broken into continuation on purpose
)

const (
	f0 = noHeader
	f1 = oneHeader
	f2 = splitHeader
	d0 = false
	d1 = true
)

// Test all 36 combinations of response frame orders:
//    (3 ways of 100-continue) * (2 ways of headers) * (2 ways of data) * (3 ways of trailers):func TestTransportResponsePattern_00f0(t *testing.T) { testTransportResponsePattern(h0, h1, false, h0) }
// Generated by http://play.golang.org/p/SScqYKJYXd
func TestTransportResPattern_c0h1d0t0(t *testing.T) { testTransportResPattern(t, f0, f1, d0, f0) }
func TestTransportResPattern_c0h1d0t1(t *testing.T) { testTransportResPattern(t, f0, f1, d0, f1) }
func TestTransportResPattern_c0h1d0t2(t *testing.T) { testTransportResPattern(t, f0, f1, d0, f2) }
func TestTransportResPattern_c0h1d1t0(t *testing.T) { testTransportResPattern(t, f0, f1, d1, f0) }
func TestTransportResPattern_c0h1d1t1(t *testing.T) { testTransportResPattern(t, f0, f1, d1, f1) }
func TestTransportResPattern_c0h1d1t2(t *testing.T) { testTransportResPattern(t, f0, f1, d1, f2) }
func TestTransportResPattern_c0h2d0t0(t *testing.T) { testTransportResPattern(t, f0, f2, d0, f0) }
func TestTransportResPattern_c0h2d0t1(t *testing.T) { testTransportResPattern(t, f0, f2, d0, f1) }
func TestTransportResPattern_c0h2d0t2(t *testing.T) { testTransportResPattern(t, f0, f2, d0, f2) }
func TestTransportResPattern_c0h2d1t0(t *testing.T) { testTransportResPattern(t, f0, f2, d1, f0) }
func TestTransportResPattern_c0h2d1t1(t *testing.T) { testTransportResPattern(t, f0, f2, d1, f1) }
func TestTransportResPattern_c0h2d1t2(t *testing.T) { testTransportResPattern(t, f0, f2, d1, f2) }
func TestTransportResPattern_c1h1d0t0(t *testing.T) { testTransportResPattern(t, f1, f1, d0, f0) }
func TestTransportResPattern_c1h1d0t1(t *testing.T) { testTransportResPattern(t, f1, f1, d0, f1) }
func TestTransportResPattern_c1h1d0t2(t *testing.T) { testTransportResPattern(t, f1, f1, d0, f2) }
func TestTransportResPattern_c1h1d1t0(t *testing.T) { testTransportResPattern(t, f1, f1, d1, f0) }
func TestTransportResPattern_c1h1d1t1(t *testing.T) { testTransportResPattern(t, f1, f1, d1, f1) }
func TestTransportResPattern_c1h1d1t2(t *testing.T) { testTransportResPattern(t, f1, f1, d1, f2) }
func TestTransportResPattern_c1h2d0t0(t *testing.T) { testTransportResPattern(t, f1, f2, d0, f0) }
func TestTransportResPattern_c1h2d0t1(t *testing.T) { testTransportResPattern(t, f1, f2, d0, f1) }
func TestTransportResPattern_c1h2d0t2(t *testing.T) { testTransportResPattern(t, f1, f2, d0, f2) }
func TestTransportResPattern_c1h2d1t0(t *testing.T) { testTransportResPattern(t, f1, f2, d1, f0) }
func TestTransportResPattern_c1h2d1t1(t *testing.T) { testTransportResPattern(t, f1, f2, d1, f1) }
func TestTransportResPattern_c1h2d1t2(t *testing.T) { testTransportResPattern(t, f1, f2, d1, f2) }
func TestTransportResPattern_c2h1d0t0(t *testing.T) { testTransportResPattern(t, f2, f1, d0, f0) }
func TestTransportResPattern_c2h1d0t1(t *testing.T) { testTransportResPattern(t, f2, f1, d0, f1) }
func TestTransportResPattern_c2h1d0t2(t *testing.T) { testTransportResPattern(t, f2, f1, d0, f2) }
func TestTransportResPattern_c2h1d1t0(t *testing.T) { testTransportResPattern(t, f2, f1, d1, f0) }
func TestTransportResPattern_c2h1d1t1(t *testing.T) { testTransportResPattern(t, f2, f1, d1, f1) }
func TestTransportResPattern_c2h1d1t2(t *testing.T) { testTransportResPattern(t, f2, f1, d1, f2) }
func TestTransportResPattern_c2h2d0t0(t *testing.T) { testTransportResPattern(t, f2, f2, d0, f0) }
func TestTransportResPattern_c2h2d0t1(t *testing.T) { testTransportResPattern(t, f2, f2, d0, f1) }
func TestTransportResPattern_c2h2d0t2(t *testing.T) { testTransportResPattern(t, f2, f2, d0, f2) }
func TestTransportResPattern_c2h2d1t0(t *testing.T) { testTransportResPattern(t, f2, f2, d1, f0) }
func TestTransportResPattern_c2h2d1t1(t *testing.T) { testTransportResPattern(t, f2, f2, d1, f1) }
func TestTransportResPattern_c2h2d1t2(t *testing.T) { testTransportResPattern(t, f2, f2, d1, f2) }

func testTransportResPattern(t *testing.T, expect100Continue, resHeader headerType, withData bool, trailers headerType) {
	const reqBody = "some request body"
	const resBody = "some response body"

	if resHeader == noHeader {
		// TODO: test 100-continue followed by immediate
		// server stream reset, without headers in the middle?
		panic("invalid combination")
	}

	ct := newClientTester(t)
	ct.client = func() error {
		req, _ := http.NewRequest("POST", "https://dummy.tld/", strings.NewReader(reqBody))
		if expect100Continue != noHeader {
			req.Header.Set("Expect", "100-continue")
		}
		res, err := ct.tr.RoundTrip(req)
		if err != nil {
			return fmt.Errorf("RoundTrip: %v", err)
		}
		defer res.Body.Close()
		if res.StatusCode != 200 {
			return fmt.Errorf("status code = %v; want 200", res.StatusCode)
		}
		slurp, err := ioutil.ReadAll(res.Body)
		if err != nil {
			return fmt.Errorf("Slurp: %v", err)
		}
		wantBody := resBody
		if !withData {
			wantBody = ""
		}
		if string(slurp) != wantBody {
			return fmt.Errorf("body = %q; want %q", slurp, wantBody)
		}
		if trailers == noHeader {
			if len(res.Trailer) > 0 {
				t.Errorf("Trailer = %v; want none", res.Trailer)
			}
		} else {
			want := http.Header{"Some-Trailer": {"some-value"}}
			if !reflect.DeepEqual(res.Trailer, want) {
				t.Errorf("Trailer = %v; want %v", res.Trailer, want)
			}
		}
		return nil
	}
	ct.server = func() error {
		ct.greet()
		var buf bytes.Buffer
		enc := hpack.NewEncoder(&buf)

		for {
			f, err := ct.fr.ReadFrame()
			if err != nil {
				return err
			}
			switch f := f.(type) {
			case *WindowUpdateFrame, *SettingsFrame:
			case *DataFrame:
				// ignore for now.
			case *HeadersFrame:
				endStream := false
				send := func(mode headerType) {
					hbf := buf.Bytes()
					switch mode {
					case oneHeader:
						ct.fr.WriteHeaders(HeadersFrameParam{
							StreamID:      f.StreamID,
							EndHeaders:    true,
							EndStream:     endStream,
							BlockFragment: hbf,
						})
					case splitHeader:
						if len(hbf) < 2 {
							panic("too small")
						}
						ct.fr.WriteHeaders(HeadersFrameParam{
							StreamID:      f.StreamID,
							EndHeaders:    false,
							EndStream:     endStream,
							BlockFragment: hbf[:1],
						})
						ct.fr.WriteContinuation(f.StreamID, true, hbf[1:])
					default:
						panic("bogus mode")
					}
				}
				if expect100Continue != noHeader {
					buf.Reset()
					enc.WriteField(hpack.HeaderField{Name: ":status", Value: "100"})
					send(expect100Continue)
				}
				// Response headers (1+ frames; 1 or 2 in this test, but never 0)
				{
					buf.Reset()
					enc.WriteField(hpack.HeaderField{Name: ":status", Value: "200"})
					enc.WriteField(hpack.HeaderField{Name: "x-foo", Value: "blah"})
					enc.WriteField(hpack.HeaderField{Name: "x-bar", Value: "more"})
					if trailers != noHeader {
						enc.WriteField(hpack.HeaderField{Name: "trailer", Value: "some-trailer"})
					}
					endStream = withData == false && trailers == noHeader
					send(resHeader)
				}
				if withData {
					endStream = trailers == noHeader
					ct.fr.WriteData(f.StreamID, endStream, []byte(resBody))
				}
				if trailers != noHeader {
					endStream = true
					buf.Reset()
					enc.WriteField(hpack.HeaderField{Name: "some-trailer", Value: "some-value"})
					send(trailers)
				}
				return nil
			}
		}
	}
	ct.run()
}