package self_test

import (
	"bufio"
	"bytes"
	"compress/gzip"
	"context"
	"crypto/tls"
	"errors"
	"fmt"
	"io"
	mrand "math/rand/v2"
	"net"
	"net/http"
	"net/http/httptrace"
	"net/textproto"
	"os"
	"strconv"
	"strings"
	"sync/atomic"
	"testing"
	"time"

	"golang.org/x/sync/errgroup"

	"github.com/quic-go/quic-go"
	"github.com/quic-go/quic-go/http3"
	"github.com/quic-go/quic-go/http3/qlog"
	quicproxy "github.com/quic-go/quic-go/integrationtests/tools/proxy"
	"github.com/quic-go/quic-go/internal/protocol"
	"github.com/quic-go/quic-go/testutils/events"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

type neverEnding byte

func (b neverEnding) Read(p []byte) (n int, err error) {
	for i := range p {
		p[i] = byte(b)
	}
	return len(p), nil
}

func randomString(length int) string {
	const alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	b := make([]byte, length)
	for i := range b {
		n := mrand.IntN(len(alphabet))
		b[i] = alphabet[n]
	}
	return string(b)
}

func startHTTPServer(t *testing.T, mux *http.ServeMux, opts ...func(*http3.Server)) (port int) {
	t.Helper()
	server := &http3.Server{
		Handler:    mux,
		TLSConfig:  getTLSConfig(),
		QUICConfig: getQuicConfig(&quic.Config{Allow0RTT: true, EnableDatagrams: true}),
	}
	for _, opt := range opts {
		opt(server)
	}

	conn := newUDPConnLocalhost(t)
	done := make(chan struct{})
	go func() {
		defer close(done)
		server.Serve(conn)
	}()

	t.Cleanup(func() {
		conn.Close()
		select {
		case <-done:
		case <-time.After(time.Second):
			t.Fatal("server didn't shut down")
		}
	})
	return conn.LocalAddr().(*net.UDPAddr).Port
}

func newHTTP3Client(t *testing.T, opts ...func(*http3.Transport)) *http.Client {
	tr := &http3.Transport{
		TLSClientConfig:    getTLSClientConfigWithoutServerName(),
		QUICConfig:         getQuicConfig(&quic.Config{MaxIdleTimeout: 10 * time.Second}),
		DisableCompression: true,
	}
	for _, opt := range opts {
		opt(tr)
	}
	addDialCallback(t, tr)
	t.Cleanup(func() { tr.Close() })
	return &http.Client{Transport: tr}
}

func TestHTTPGet(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, "Hello, World!\n")
	})
	mux.HandleFunc("/long", func(w http.ResponseWriter, r *http.Request) {
		w.Write(PRDataLong)
	})
	port := startHTTPServer(t, mux)

	cl := newHTTP3Client(t)

	t.Run("small", func(t *testing.T) {
		resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/hello", port))
		require.NoError(t, err)
		require.Equal(t, http.StatusOK, resp.StatusCode)
		body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 2 * time.Second})
		require.NoError(t, err)
		require.Equal(t, "Hello, World!\n", string(body))
	})

	t.Run("big", func(t *testing.T) {
		resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/long", port))
		require.NoError(t, err)
		require.Equal(t, http.StatusOK, resp.StatusCode)
		body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 10 * time.Second})
		require.NoError(t, err)
		require.Equal(t, PRDataLong, body)
	})
}

func TestHTTPPost(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/echo", func(w http.ResponseWriter, r *http.Request) {
		io.Copy(w, r.Body)
	})
	port := startHTTPServer(t, mux)

	cl := newHTTP3Client(t)

	t.Run("small", func(t *testing.T) {
		resp, err := cl.Post(
			fmt.Sprintf("https://localhost:%d/echo", port),
			"text/plain",
			bytes.NewReader([]byte("Hello, world!")),
		)
		require.NoError(t, err)
		require.Equal(t, http.StatusOK, resp.StatusCode)
		body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 2 * time.Second})
		require.NoError(t, err)
		require.Equal(t, []byte("Hello, world!"), body)
	})

	t.Run("big", func(t *testing.T) {
		resp, err := cl.Post(
			fmt.Sprintf("https://localhost:%d/echo", port),
			"text/plain",
			bytes.NewReader(PRData),
		)
		require.NoError(t, err)
		require.Equal(t, http.StatusOK, resp.StatusCode)
		body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 10 * time.Second})
		require.NoError(t, err)
		require.Equal(t, PRData, body)
	})
}

func TestHTTPMultipleRequests(t *testing.T) {
	mux := http.NewServeMux()
	port := startHTTPServer(t, mux)

	t.Run("reading the response", func(t *testing.T) {
		mux.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
			io.WriteString(w, "Hello, World!\n")
		})

		cl := newHTTP3Client(t)
		var eg errgroup.Group
		for i := 0; i < 200; i++ {
			eg.Go(func() error {
				resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/hello", port))
				if err != nil {
					return err
				}
				if resp.StatusCode != http.StatusOK {
					return fmt.Errorf("unexpected status code: %d", resp.StatusCode)
				}
				body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 3 * time.Second})
				if err != nil {
					return err
				}
				if string(body) != "Hello, World!\n" {
					return fmt.Errorf("unexpected body: %q", body)
				}
				return nil
			})
		}
		require.NoError(t, eg.Wait())
	})

	t.Run("not reading the response", func(t *testing.T) {
		mux.HandleFunc("/prdata", func(w http.ResponseWriter, r *http.Request) {
			w.Write(PRData)
		})

		cl := newHTTP3Client(t)
		const num = 150

		for i := 0; i < num; i++ {
			resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/prdata", port))
			require.NoError(t, err)
			require.Equal(t, http.StatusOK, resp.StatusCode)
			require.NoError(t, resp.Body.Close())
		}
	})
}

func TestContentLengthForSmallResponse(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/small", func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, "foo")
		io.WriteString(w, "bar")
	})
	port := startHTTPServer(t, mux)

	resp, err := newHTTP3Client(t).Get(fmt.Sprintf("https://localhost:%d/small", port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	require.Equal(t, "6", resp.Header.Get("Content-Length"))
}

func TestHTTPHeaders(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/headers/response", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("foo", "bar")
		w.Header().Set("lorem", "ipsum")
		w.Header().Set("echo", r.Header.Get("echo"))
	})
	port := startHTTPServer(t, mux)

	req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("https://localhost:%d/headers/response", port), nil)
	require.NoError(t, err)
	echoHdr := randomString(128)
	req.Header.Set("echo", echoHdr)

	resp, err := newHTTP3Client(t).Do(req)
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	require.Equal(t, "bar", resp.Header.Get("foo"))
	require.Equal(t, "ipsum", resp.Header.Get("lorem"))
	require.Equal(t, echoHdr, resp.Header.Get("echo"))
}

func TestHTTPHeaderSizeLimitServer(t *testing.T) {
	t.Run("large HEADERS frame", func(t *testing.T) {
		const limit = 1024
		hdr := make(http.Header)
		for range 20 {
			hdr.Add(randomString(50), randomString(50))
		}
		headersFrameSize := testHTTPHeaderSizeLimitServer(t, hdr, limit)
		require.Greater(t, headersFrameSize, limit)
	})

	t.Run("large decompressed HEADERS frame", func(t *testing.T) {
		const limit = 1024
		hdr := make(http.Header)
		for range 200 {
			// This is a QPACK static table entry, so it will be compressed.
			hdr.Add("content-type", "text/plain;charset=utf-8")
		}
		headersFrameSize := testHTTPHeaderSizeLimitServer(t, hdr, limit)
		require.Less(t, headersFrameSize, limit)
	})
}

func testHTTPHeaderSizeLimitServer(t *testing.T, hdr http.Header, limit int) (headersFrameSize int) {
	mux := http.NewServeMux()
	var handlerCalled bool
	mux.HandleFunc("/headers", func(w http.ResponseWriter, r *http.Request) {
		handlerCalled = true
	})
	port := startHTTPServer(t, mux, func(s *http3.Server) { s.MaxHeaderBytes = limit })

	var eventRecorder events.Recorder
	cl := newHTTP3Client(t, func(tr *http3.Transport) {
		tr.QUICConfig = getQuicConfig(&quic.Config{
			MaxIdleTimeout: 10 * time.Second,
			Tracer:         newTracer(&eventRecorder),
		})
	})

	req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("https://localhost:%d/headers", port), nil)
	require.NoError(t, err)
	req.Header = hdr

	resp, err := cl.Do(req)
	require.NoError(t, err)
	require.Equal(t, http.StatusRequestHeaderFieldsTooLarge, resp.StatusCode)
	require.False(t, handlerCalled)

	for _, ev := range eventRecorder.Events(qlog.FrameCreated{}) {
		fc := ev.(qlog.FrameCreated)
		if _, ok := fc.Frame.Frame.(qlog.HeadersFrame); ok {
			headersFrameSize = fc.Raw.Length
			break
		}
	}
	return headersFrameSize
}

func TestHTTPHeaderSizeLimitClient(t *testing.T) {
	t.Run("large HEADERS frame", func(t *testing.T) {
		const limit = 1024
		hdr := make(http.Header)
		for range 20 {
			hdr.Add(randomString(50), randomString(50))
		}
		headersFrameSize, requestErr := testHTTPHeaderSizeLimitClient(t, hdr, limit)
		require.ErrorContains(t, requestErr, "http3: HEADERS frame too large")
		require.Greater(t, headersFrameSize, limit)
	})

	t.Run("large decompressed HEADERS frame", func(t *testing.T) {
		const limit = 1024
		hdr := make(http.Header)
		for range 200 {
			// This is a QPACK static table entry, so it will be compressed.
			hdr.Add("content-type", "text/plain;charset=utf-8")
		}
		headersFrameSize, requestErr := testHTTPHeaderSizeLimitClient(t, hdr, limit)
		require.ErrorContains(t, requestErr, "http3: headers too large")
		require.Less(t, headersFrameSize, limit)
	})
}

func testHTTPHeaderSizeLimitClient(t *testing.T, hdr http.Header, limit int) (headersFrameSize int, requestErr error) {
	mux := http.NewServeMux()
	var handlerCalled atomic.Bool
	mux.HandleFunc("/headers", func(w http.ResponseWriter, r *http.Request) {
		handlerCalled.Store(true)
		for k, v := range hdr {
			for _, val := range v {
				w.Header().Add(k, val)
			}
		}
	})
	port := startHTTPServer(t, mux)

	var eventRecorder events.Recorder
	cl := newHTTP3Client(t,
		func(tr *http3.Transport) {
			tr.MaxResponseHeaderBytes = limit
			tr.QUICConfig = getQuicConfig(&quic.Config{
				MaxIdleTimeout: 10 * time.Second,
				Tracer:         newTracer(&eventRecorder),
			})
		},
	)

	req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("https://localhost:%d/headers", port), nil)
	require.NoError(t, err)

	_, requestErr = cl.Do(req)
	require.Error(t, requestErr)
	require.True(t, handlerCalled.Load())

	var found bool
	for _, ev := range eventRecorder.Events(qlog.FrameParsed{}) {
		fp := ev.(qlog.FrameParsed)
		if _, ok := fp.Frame.Frame.(qlog.HeadersFrame); ok {
			headersFrameSize = fp.Raw.PayloadLength
			found = true
			break
		}
	}
	require.True(t, found)
	return headersFrameSize, requestErr
}

func TestHTTPResponseTrailers(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/trailers", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Trailer", "AtEnd1, AtEnd2")
		w.Header().Add("Trailer", "Never")
		w.Header().Add("Trailer", "LAST")
		w.Header().Set("Content-Type", "text/plain; charset=utf-8") // normal header
		w.WriteHeader(http.StatusOK)
		w.Header().Set("AtEnd1", "value 1")
		io.WriteString(w, "This HTTP response has both headers before this text and trailers at the end.\n")
		w.(http.Flusher).Flush()
		w.Header().Set("AtEnd2", "value 2")
		io.WriteString(w, "More text\n")
		w.(http.Flusher).Flush()
		w.Header().Set("LAST", "value 3")
		w.Header().Set(http.TrailerPrefix+"Unannounced", "Surprise!")
		w.Header().Set("Late-Header", "No surprise!")
	})

	port := startHTTPServer(t, mux)

	resp, err := newHTTP3Client(t).Get(fmt.Sprintf("https://localhost:%d/trailers", port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	require.Empty(t, resp.Header.Get("Trailer"))
	require.NotContains(t, resp.Header, "Atend1")
	require.NotContains(t, resp.Header, "Atend2")
	require.NotContains(t, resp.Header, "Never")
	require.NotContains(t, resp.Header, "Last")
	require.NotContains(t, resp.Header, "Late-Header")
	require.Equal(t, http.Header(map[string][]string{
		"Atend1": nil,
		"Atend2": nil,
		"Never":  nil,
		"Last":   nil,
	}), resp.Trailer)

	body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 3 * time.Second})
	require.NoError(t, err)
	require.Equal(t, "This HTTP response has both headers before this text and trailers at the end.\nMore text\n", string(body))
	for k := range resp.Header {
		require.NotContains(t, k, http.TrailerPrefix)
	}
	require.Equal(t, http.Header(map[string][]string{
		"Atend1":      {"value 1"},
		"Atend2":      {"value 2"},
		"Last":        {"value 3"},
		"Unannounced": {"Surprise!"},
	}), resp.Trailer)
}

func TestHTTPRequestTrailers(t *testing.T) {
	trailerChan := make(chan http.Header, 2)
	bodyChan := make(chan string, 1)

	mux := http.NewServeMux()
	mux.HandleFunc("/client-trailers", func(w http.ResponseWriter, r *http.Request) {
		trailerBeforeBody := make(http.Header)
		for k, v := range r.Trailer {
			trailerBeforeBody[k] = v
		}
		trailerChan <- trailerBeforeBody

		body, err := io.ReadAll(r.Body)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		bodyChan <- string(body)

		trailer := make(http.Header)
		for k, v := range r.Trailer {
			trailer[k] = v
		}
		trailerChan <- trailer

		w.WriteHeader(http.StatusOK)
	})

	port := startHTTPServer(t, mux)

	pr, pw := io.Pipe()
	req, err := http.NewRequest(http.MethodPost, fmt.Sprintf("https://localhost:%d/client-trailers", port), pr)
	require.NoError(t, err)
	req.Trailer = http.Header{
		"Trailer1": nil,
		"Trailer2": {"to-be-updated"},
	}

	go func() {
		// send the first half of the body
		pw.Write(PRData[:len(PRData)/2])
		// then update the trailer values
		req.Trailer.Set("Trailer1", "foo")
		req.Trailer.Set("Trailer2", "bar")
		req.Trailer.Set("Trailer3", "baz")
		// send the rest of the body
		pw.Write(PRData[len(PRData)/2:])
		pw.Close()
	}()

	resp, err := newHTTP3Client(t).Do(req)
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)

	select {
	case trailersBefore := <-trailerChan:
		// trailers before body should have announced keys with nil values
		require.Equal(t, http.Header(map[string][]string{"Trailer1": nil, "Trailer2": nil}), trailersBefore)
	case <-time.After(time.Second):
		t.Fatal("timeout waiting for trailer announcement")
	}

	select {
	case body := <-bodyChan:
		require.Equal(t, string(PRData), body)
	case <-time.After(time.Second):
		t.Fatal("timeout waiting for body")
	}

	select {
	case trailers := <-trailerChan:
		require.Equal(t, http.Header(map[string][]string{
			"Trailer1": {"foo"},
			"Trailer2": {"bar"},
			"Trailer3": {"baz"},
		}), trailers)
	case <-time.After(time.Second):
		t.Fatal("timeout waiting for trailers")
	}
}

func TestHTTPErrAbortHandler(t *testing.T) {
	respChan := make(chan struct{})
	mux := http.NewServeMux()
	mux.HandleFunc("/abort", func(w http.ResponseWriter, r *http.Request) {
		// no recover here as it will interfere with the handler
		io.WriteString(w, "foobar")
		w.(http.Flusher).Flush()
		// wait for the client to receive the response
		<-respChan
		panic(http.ErrAbortHandler)
	})
	port := startHTTPServer(t, mux)

	resp, err := newHTTP3Client(t).Get(fmt.Sprintf("https://localhost:%d/abort", port))
	close(respChan)
	require.NoError(t, err)
	body, err := io.ReadAll(resp.Body)
	require.Error(t, err)
	var h3Err *http3.Error
	require.True(t, errors.As(err, &h3Err))
	require.Equal(t, http3.ErrCodeInternalError, h3Err.ErrorCode)
	// the body will be a prefix of what's written
	require.True(t, bytes.HasPrefix([]byte("foobar"), body))
}

func TestHTTPGzip(t *testing.T) {
	mux := http.NewServeMux()
	var acceptEncoding string
	mux.HandleFunc("/hellogz", func(w http.ResponseWriter, r *http.Request) {
		acceptEncoding = r.Header.Get("Accept-Encoding")
		w.Header().Set("Content-Encoding", "gzip")
		w.Header().Set("foo", "bar")

		gw := gzip.NewWriter(w)
		defer gw.Close()
		_, err := gw.Write([]byte("Hello, World!\n"))
		require.NoError(t, err)
	})
	port := startHTTPServer(t, mux)

	cl := newHTTP3Client(t)
	cl.Transport.(*http3.Transport).DisableCompression = false
	resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/hellogz", port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	require.True(t, resp.Uncompressed)

	body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 3 * time.Second})
	require.NoError(t, err)
	require.Equal(t, "Hello, World!\n", string(body))

	// make sure the server received the Accept-Encoding header
	require.Equal(t, "gzip", acceptEncoding)
}

func TestHTTPDifferentOrigins(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/remote-addr", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("X-RemoteAddr", r.RemoteAddr)
		w.WriteHeader(http.StatusOK)
	})
	port := startHTTPServer(t, mux)

	tr := &http3.Transport{
		TLSClientConfig: getTLSClientConfigWithoutServerName(),
		QUICConfig:      getQuicConfig(nil),
	}
	t.Cleanup(func() { tr.Close() })
	cl := &http.Client{Transport: tr}

	resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/remote-addr", port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	addr1 := resp.Header.Get("X-RemoteAddr")
	require.NotEmpty(t, addr1)
	resp, err = cl.Get(fmt.Sprintf("https://127.0.0.1:%d/remote-addr", port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	addr2 := resp.Header.Get("X-RemoteAddr")
	require.NotEmpty(t, addr2)
	require.Equal(t, addr1, addr2)
}

func TestHTTPServerIdleTimeout(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, "Hello, World!\n")
	})
	idleTimeout := scaleDuration(10 * time.Millisecond)
	port := startHTTPServer(t, mux, func(s *http3.Server) { s.IdleTimeout = idleTimeout })

	connChan := make(chan *quic.Conn, 1)
	tr := &http3.Transport{
		TLSClientConfig: getTLSClientConfigWithoutServerName(),
		Dial: func(ctx context.Context, addr string, tlsCfg *tls.Config, cfg *quic.Config) (*quic.Conn, error) {
			conn, err := quic.DialAddrEarly(ctx, addr, tlsCfg, cfg)
			connChan <- conn
			return conn, err
		},
	}
	t.Cleanup(func() { tr.Close() })
	cl := &http.Client{Transport: tr}

	_, err := cl.Get(fmt.Sprintf("https://localhost:%d/hello", port))
	require.NoError(t, err)

	var conn *quic.Conn
	select {
	case conn = <-connChan:
	case <-time.After(time.Second):
		t.Fatal("connection was not opened")
	}

	select {
	case <-time.After(3 * idleTimeout):
		t.Fatal("connection was not closed")
	case <-conn.Context().Done():
	}
}

func TestHTTPReestablishConnectionAfterDialError(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, "Hello, World!\n")
	})
	port := startHTTPServer(t, mux)

	var dialCounter int
	cl := http.Client{
		Transport: &http3.Transport{
			TLSClientConfig: getTLSClientConfig(),
			Dial: func(ctx context.Context, addr string, tlsConf *tls.Config, conf *quic.Config) (*quic.Conn, error) {
				dialCounter++
				if dialCounter == 1 { // make the first dial fail
					return nil, assert.AnError
				}
				return quic.DialAddrEarly(ctx, addr, tlsConf, conf)
			},
		},
	}
	defer cl.Transport.(io.Closer).Close()

	_, err := cl.Get(fmt.Sprintf("https://localhost:%d/hello", port))
	require.ErrorIs(t, err, assert.AnError)
	resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/hello", port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
}

func TestHTTPClientRequestContextCancellation(t *testing.T) {
	mux := http.NewServeMux()
	port := startHTTPServer(t, mux)
	cl := newHTTP3Client(t)

	t.Run("before response", func(t *testing.T) {
		mux.HandleFunc("/cancel-before", func(w http.ResponseWriter, r *http.Request) {
			<-r.Context().Done()
		})

		ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
		defer cancel()
		req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("https://localhost:%d/cancel-before", port), nil)
		require.NoError(t, err)
		_, err = cl.Do(req)
		require.Error(t, err)
		require.ErrorIs(t, err, context.DeadlineExceeded)
	})

	t.Run("after response", func(t *testing.T) {
		errChan := make(chan error, 1)
		mux.HandleFunc("/cancel-after", func(w http.ResponseWriter, r *http.Request) {
			// TODO(#4508): check for request context cancellations
			for {
				if _, err := io.WriteString(w, "foobar"); err != nil {
					errChan <- err
					return
				}
			}
		})

		ctx, cancel := context.WithCancel(context.Background())
		req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("https://localhost:%d/cancel-after", port), nil)
		require.NoError(t, err)
		resp, err := cl.Do(req)
		require.NoError(t, err)
		require.Equal(t, http.StatusOK, resp.StatusCode)
		cancel()

		select {
		case err := <-errChan:
			require.Error(t, err)
			var http3Err *http3.Error
			require.True(t, errors.As(err, &http3Err))
			require.Equal(t, http3.ErrCodeRequestCanceled, http3Err.ErrorCode)
			require.True(t, http3Err.Remote)
		case <-time.After(time.Second):
			t.Fatal("handler was not called")
		}

		_, err = resp.Body.Read([]byte{0})
		var http3Err *http3.Error
		require.True(t, errors.As(err, &http3Err))
		require.Equal(t, http3.ErrCodeRequestCanceled, http3Err.ErrorCode)
		require.False(t, http3Err.Remote)
	})
}

func TestHTTPDeadlines(t *testing.T) {
	const deadlineDelay = 50 * time.Millisecond

	mux := http.NewServeMux()
	port := startHTTPServer(t, mux)
	cl := newHTTP3Client(t)

	t.Run("read deadline", func(t *testing.T) {
		type result struct {
			body []byte
			err  error
		}

		resultChan := make(chan result, 1)
		mux.HandleFunc("/read-deadline", func(w http.ResponseWriter, r *http.Request) {
			rc := http.NewResponseController(w)
			require.NoError(t, rc.SetReadDeadline(time.Now().Add(deadlineDelay)))
			body, err := io.ReadAll(r.Body)
			resultChan <- result{body: body, err: err}
			io.WriteString(w, "ok")
		})

		expectedEnd := time.Now().Add(deadlineDelay)
		resp, err := cl.Post(
			fmt.Sprintf("https://localhost:%d/read-deadline", port),
			"text/plain",
			neverEnding('a'),
		)
		require.NoError(t, err)
		require.Equal(t, http.StatusOK, resp.StatusCode)

		body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 2 * deadlineDelay})
		require.NoError(t, err)
		require.True(t, time.Now().After(expectedEnd))
		require.Equal(t, "ok", string(body))

		select {
		case result := <-resultChan:
			require.ErrorIs(t, result.err, os.ErrDeadlineExceeded)
			require.Contains(t, string(result.body), "aa")
		default:
			t.Fatal("handler was not called")
		}
	})

	t.Run("write deadline", func(t *testing.T) {
		errChan := make(chan error, 1)
		mux.HandleFunc("/write-deadline", func(w http.ResponseWriter, r *http.Request) {
			rc := http.NewResponseController(w)
			require.NoError(t, rc.SetWriteDeadline(time.Now().Add(deadlineDelay)))

			_, err := io.Copy(w, neverEnding('a'))
			errChan <- err
		})

		expectedEnd := time.Now().Add(deadlineDelay)

		resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/write-deadline", port))
		require.NoError(t, err)
		require.Equal(t, http.StatusOK, resp.StatusCode)

		body, err := io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 2 * deadlineDelay})
		require.NoError(t, err)
		require.True(t, time.Now().After(expectedEnd))
		require.Contains(t, string(body), "aa")

		select {
		case err := <-errChan:
			require.ErrorIs(t, err, os.ErrDeadlineExceeded)
		case <-time.After(2 * deadlineDelay):
			t.Fatal("handler was not called")
		}
	})
}

func TestHTTPServeQUICConn(t *testing.T) {
	tlsConf := getTLSConfig()
	tlsConf.NextProtos = []string{http3.NextProtoH3}
	ln, err := quic.Listen(newUDPConnLocalhost(t), tlsConf, getQuicConfig(nil))
	require.NoError(t, err)
	defer ln.Close()

	mux := http.NewServeMux()
	mux.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, "Hello, World!\n")
	})
	server := &http3.Server{
		TLSConfig:  tlsConf,
		QUICConfig: getQuicConfig(nil),
		Handler:    mux,
	}
	errChan := make(chan error, 1)
	go func() {
		conn, err := ln.Accept(context.Background())
		if err != nil {
			errChan <- fmt.Errorf("failed to accept QUIC connection: %w", err)
			return
		}
		errChan <- server.ServeQUICConn(conn) // returns once the client closes
	}()

	cl := newHTTP3Client(t)
	resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/hello", ln.Addr().(*net.UDPAddr).Port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)

	require.NoError(t, cl.Transport.(io.Closer).Close())
	select {
	case err := <-errChan:
		require.Error(t, err)
		require.ErrorContains(t, err, "accepting stream failed")
	case <-time.After(time.Second):
		t.Fatal("server didn't shut down")
	}
}

func TestHTTPContextFromQUIC(t *testing.T) {
	conn := newUDPConnLocalhost(t)
	tr := &quic.Transport{
		Conn: conn,
		ConnContext: func(ctx context.Context, _ *quic.ClientInfo) (context.Context, error) {
			return context.WithValue(ctx, "foo", "bar"), nil
		},
	}
	defer tr.Close()
	tlsConf := getTLSConfig()
	tlsConf.NextProtos = []string{http3.NextProtoH3}
	ln, err := tr.Listen(tlsConf, getQuicConfig(nil))
	require.NoError(t, err)
	defer ln.Close()

	mux := http.NewServeMux()
	ctxChan := make(chan context.Context, 1)
	mux.HandleFunc("/quic-conn-context", func(w http.ResponseWriter, r *http.Request) {
		ctxChan <- r.Context()
	})

	server := &http3.Server{Handler: mux}
	go func() {
		c, err := ln.Accept(context.Background())
		require.NoError(t, err)
		server.ServeQUICConn(c)
	}()

	cl := newHTTP3Client(t)
	resp, err := cl.Get(fmt.Sprintf("https://localhost:%d/quic-conn-context", conn.LocalAddr().(*net.UDPAddr).Port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)

	select {
	case ctx := <-ctxChan:
		v, ok := ctx.Value("foo").(string)
		require.True(t, ok)
		require.Equal(t, "bar", v)
	default:
		t.Fatal("context not set")
	}
}

func TestHTTPConnContext(t *testing.T) {
	mux := http.NewServeMux()
	requestCtxChan := make(chan context.Context, 1)
	mux.HandleFunc("/context", func(w http.ResponseWriter, r *http.Request) {
		requestCtxChan <- r.Context()
	})

	var server *http3.Server
	connCtxChan := make(chan context.Context, 1)
	port := startHTTPServer(t,
		mux,
		func(s *http3.Server) { server = s },
		func(s *http3.Server) {
			s.ConnContext = func(ctx context.Context, c *quic.Conn) context.Context {
				connCtxChan <- ctx
				ctx = context.WithValue(ctx, "foo", "bar")
				return ctx
			}
		},
	)

	resp, err := newHTTP3Client(t).Get(fmt.Sprintf("https://localhost:%d/context", port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)

	select {
	case ctx := <-connCtxChan:
		serv, ok := ctx.Value(http3.ServerContextKey).(*http3.Server)
		require.True(t, ok)
		require.Equal(t, server, serv)
	default:
		t.Fatal("handler was not called")
	}

	select {
	case ctx := <-requestCtxChan:
		v, ok := ctx.Value("foo").(string)
		require.True(t, ok)
		require.Equal(t, "bar", v)

		serv, ok := ctx.Value(http3.ServerContextKey).(*http3.Server)
		require.True(t, ok)
		require.Equal(t, server, serv)
	default:
		t.Fatal("handler was not called")
	}
}

func TestHTTPRemoteAddrContextKey(t *testing.T) {
	ctxChan := make(chan context.Context, 1)
	mux := http.NewServeMux()
	mux.HandleFunc("/remote-addr", func(w http.ResponseWriter, r *http.Request) {
		ctxChan <- r.Context()
	})

	port := startHTTPServer(t, mux)

	resp, err := newHTTP3Client(t).Get(fmt.Sprintf("https://localhost:%d/remote-addr", port))
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)

	select {
	case ctx := <-ctxChan:
		_, ok := ctx.Value(http3.RemoteAddrContextKey).(net.Addr)
		require.True(t, ok)
		require.Equal(t, "127.0.0.1", ctx.Value(http3.RemoteAddrContextKey).(*net.UDPAddr).IP.String())
	default:
		t.Fatal("handler was not called")
	}
}

func TestHTTPStreamedRequests(t *testing.T) {
	errChan := make(chan error, 1)
	mux := http.NewServeMux()
	mux.HandleFunc("/echoline", func(w http.ResponseWriter, r *http.Request) {
		defer close(errChan)
		w.WriteHeader(200)
		w.(http.Flusher).Flush()
		reader := bufio.NewReader(r.Body)
		for {
			msg, err := reader.ReadString('\n')
			if err != nil {
				return
			}
			if _, err := io.WriteString(w, msg); err != nil {
				errChan <- err
				return
			}
			w.(http.Flusher).Flush()
		}
	})

	port := startHTTPServer(t, mux)

	r, w := io.Pipe()
	req, err := http.NewRequest(http.MethodPut, fmt.Sprintf("https://localhost:%d/echoline", port), r)
	require.NoError(t, err)
	client := newHTTP3Client(t)
	rsp, err := client.Do(req)
	require.NoError(t, err)
	require.Equal(t, 200, rsp.StatusCode)

	reader := bufio.NewReader(rsp.Body)
	for i := 0; i < 5; i++ {
		msg := fmt.Sprintf("Hello world, %d!\n", i)
		fmt.Fprint(w, msg)
		msgRcvd, err := reader.ReadString('\n')
		require.NoError(t, err)
		require.Equal(t, msg, msgRcvd)
	}
	require.NoError(t, req.Body.Close())

	select {
	case err := <-errChan:
		require.NoError(t, err)
	case <-time.After(time.Second):
		t.Fatal("handler did not complete")
	}
}

func TestHTTP1xxResponse(t *testing.T) {
	header1 := "</style.css>; rel=preload; as=style"
	header2 := "</script.js>; rel=preload; as=script"
	data := "1xx-test-data"
	mux := http.NewServeMux()
	mux.HandleFunc("/103-early-data", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Add("Link", header1)
		w.Header().Add("Link", header2)
		w.WriteHeader(http.StatusEarlyHints)
		io.WriteString(w, data)
		w.WriteHeader(http.StatusOK)
	})

	port := startHTTPServer(t, mux)

	var (
		cnt    int
		status int
		hdr    textproto.MIMEHeader
	)
	ctx := httptrace.WithClientTrace(context.Background(), &httptrace.ClientTrace{
		Got1xxResponse: func(code int, header textproto.MIMEHeader) error {
			hdr = header
			status = code
			cnt++
			return nil
		},
	})

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("https://localhost:%d/103-early-data", port), nil)
	require.NoError(t, err)
	resp, err := newHTTP3Client(t).Do(req)
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, data, string(body))
	require.Equal(t, http.StatusEarlyHints, status)
	require.Equal(t, []string{header1, header2}, hdr.Values("Link"))
	require.Equal(t, 1, cnt)
	require.Equal(t, []string{header1, header2}, resp.Header.Values("Link"))
	require.NoError(t, resp.Body.Close())
}

func TestHTTP1xxTerminalResponse(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/101-switch-protocols", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Add("foo", "bar")
		w.WriteHeader(http.StatusSwitchingProtocols)
	})

	port := startHTTPServer(t, mux)

	var (
		cnt    int
		status int
	)
	ctx := httptrace.WithClientTrace(context.Background(), &httptrace.ClientTrace{
		Got1xxResponse: func(code int, header textproto.MIMEHeader) error {
			status = code
			cnt++
			return nil
		},
	})

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("https://localhost:%d/101-switch-protocols", port), nil)
	require.NoError(t, err)
	resp, err := newHTTP3Client(t).Do(req)
	require.NoError(t, err)
	require.Equal(t, http.StatusSwitchingProtocols, resp.StatusCode)
	require.Equal(t, "bar", resp.Header.Get("Foo"))
	require.Zero(t, status)
	require.Zero(t, cnt)
	require.NoError(t, resp.Body.Close())
}

func TestHTTP0RTT(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/0rtt", func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, strconv.FormatBool(!r.TLS.HandshakeComplete))
	})
	port := startHTTPServer(t, mux)

	var num0RTTPackets atomic.Uint32
	proxy := quicproxy.Proxy{
		Conn:       newUDPConnLocalhost(t),
		ServerAddr: &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: port},
		DelayPacket: func(_ quicproxy.Direction, _, _ net.Addr, data []byte) time.Duration {
			if containsPacketType(data, protocol.PacketType0RTT) {
				num0RTTPackets.Add(1)
			}
			return scaleDuration(25 * time.Millisecond)
		},
	}
	require.NoError(t, proxy.Start())
	defer proxy.Close()

	tlsConf := getTLSClientConfigWithoutServerName()
	puts := make(chan string, 10)
	tlsConf.ClientSessionCache = newClientSessionCache(tls.NewLRUClientSessionCache(10), nil, puts)
	tr := &http3.Transport{
		TLSClientConfig:    tlsConf,
		QUICConfig:         getQuicConfig(&quic.Config{MaxIdleTimeout: 10 * time.Second}),
		DisableCompression: true,
	}
	defer tr.Close()
	addDialCallback(t, tr)

	proxyPort := proxy.LocalAddr().(*net.UDPAddr).Port
	req, err := http.NewRequest(http3.MethodGet0RTT, fmt.Sprintf("https://localhost:%d/0rtt", proxyPort), nil)
	require.NoError(t, err)
	rsp, err := tr.RoundTrip(req)
	require.NoError(t, err)
	require.Equal(t, 200, rsp.StatusCode)
	data, err := io.ReadAll(rsp.Body)
	require.NoError(t, err)
	require.Equal(t, "false", string(data))
	require.Zero(t, num0RTTPackets.Load())

	select {
	case <-puts:
	case <-time.After(time.Second):
		t.Fatal("did not receive session ticket")
	}

	tr2 := &http3.Transport{
		TLSClientConfig:    tr.TLSClientConfig,
		QUICConfig:         tr.QUICConfig,
		DisableCompression: true,
	}
	defer tr2.Close()
	addDialCallback(t, tr2)
	rsp, err = tr2.RoundTrip(req)
	require.NoError(t, err)
	require.Equal(t, 200, rsp.StatusCode)
	data, err = io.ReadAll(rsp.Body)
	require.NoError(t, err)
	require.Equal(t, "true", string(data))
	require.NotZero(t, num0RTTPackets.Load())
}

func TestHTTPStreamer(t *testing.T) {
	mux := http.NewServeMux()
	mux.HandleFunc("/httpstreamer", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)

		str := w.(http3.HTTPStreamer).HTTPStream()
		str.Write([]byte("foobar"))

		// Do this in a Go routine, so that the handler returns early.
		// This way, we can also check that the HTTP/3 doesn't close the stream.
		go func() {
			defer str.Close()
			_, _ = io.Copy(str, str)
		}()
	})

	port := startHTTPServer(t, mux)

	req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("https://localhost:%d/httpstreamer", port), nil)
	require.NoError(t, err)
	tlsConf := getTLSClientConfigWithoutServerName()
	tlsConf.NextProtos = []string{http3.NextProtoH3}
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	conn, err := quic.Dial(ctx, newUDPConnLocalhost(t), &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: port}, tlsConf, getQuicConfig(nil))
	require.NoError(t, err)
	defer conn.CloseWithError(0, "")
	tr := http3.Transport{}
	addDialCallback(t, &tr)
	cc := tr.NewClientConn(conn)
	str, err := cc.OpenRequestStream(ctx)
	require.NoError(t, err)
	require.NoError(t, str.SendRequestHeader(req))

	rsp, err := str.ReadResponse()
	require.NoError(t, err)
	require.Equal(t, 200, rsp.StatusCode)

	b := make([]byte, 6)
	_, err = io.ReadFull(str, b)
	require.NoError(t, err)
	require.Equal(t, []byte("foobar"), b)

	_, err = str.Write(PRData)
	require.NoError(t, err)
	require.NoError(t, str.Close())
	repl, err := io.ReadAll(str)
	require.NoError(t, err)
	require.Equal(t, PRData, repl)
}

type blackHoleConn struct {
	net.PacketConn
	block atomic.Bool
	close chan struct{}
}

func (c *blackHoleConn) WriteTo(b []byte, addr net.Addr) (int, error) {
	return c.PacketConn.WriteTo(b, addr)
}

func (c *blackHoleConn) ReadFrom(b []byte) (int, net.Addr, error) {
	if c.block.Load() {
		<-c.close
		return 0, nil, errors.New("blocked")
	}
	n, _, err := c.PacketConn.ReadFrom(b)
	if c.block.Load() {
		<-c.close
		return 0, nil, errors.New("blocked")
	}
	return n, nil, err
}

func (c *blackHoleConn) Close() error {
	close(c.close)
	return c.PacketConn.Close()
}

func (c *blackHoleConn) StartBlocking() { c.block.Store(true) }

func TestHTTPRequestRetryAfterIdleTimeout(t *testing.T) {
	t.Run("only cached conn", func(t *testing.T) {
		testHTTPRequestRetryAfterIdleTimeout(t, true)
	})
	t.Run("allow re-dialing", func(t *testing.T) {
		testHTTPRequestRetryAfterIdleTimeout(t, false)
	})
}

func testHTTPRequestRetryAfterIdleTimeout(t *testing.T, onlyCachedConn bool) {
	t.Setenv("QUIC_GO_DISABLE_RECEIVE_BUFFER_WARNING", "true")

	mux := http.NewServeMux()
	mux.HandleFunc("/remote-addr", func(w http.ResponseWriter, r *http.Request) {
		io.WriteString(w, r.RemoteAddr)
	})
	port := startHTTPServer(t, mux, func(s *http3.Server) {})

	firstConn := &blackHoleConn{PacketConn: newUDPConnLocalhost(t), close: make(chan struct{})}
	secondConn := newUDPConnLocalhost(t)
	conns := []net.PacketConn{firstConn, secondConn}
	require.NotEqual(t, firstConn.LocalAddr().String(), secondConn.LocalAddr().String())

	idleTimeout := scaleDuration(10 * time.Millisecond)
	connChan := make(chan *quic.Conn, 2)
	tr := &http3.Transport{
		TLSClientConfig: getTLSClientConfigWithoutServerName(),
		QUICConfig:      getQuicConfig(&quic.Config{MaxIdleTimeout: idleTimeout}),
		Dial: func(ctx context.Context, a string, tlsCfg *tls.Config, cfg *quic.Config) (*quic.Conn, error) {
			conn := conns[0]
			conns = conns[1:]
			addr, err := net.ResolveUDPAddr("udp", a)
			if err != nil {
				return nil, err
			}
			c, err := quic.DialEarly(ctx, conn, addr, tlsCfg, cfg)
			if err != nil {
				return nil, err
			}
			connChan <- c
			return c, nil
		},
		DisableCompression: true,
	}
	t.Cleanup(func() { tr.Close() })

	var headersCount int
	req, err := http.NewRequestWithContext(
		httptrace.WithClientTrace(context.Background(), &httptrace.ClientTrace{
			WroteHeaders: func() { headersCount++ },
		}),
		http.MethodGet,
		fmt.Sprintf("https://127.0.0.1:%d/remote-addr", port),
		// Add a body (wrappped so that http.NewRequest doesn't set the GetBody callback),
		// to make it impossible to retry this request.
		// This tests that the detection logic works properly:
		// If the request fails before the stream can be opened, it is always safe to retry.
		io.LimitReader(strings.NewReader("foobar"), 1000),
	)
	require.NoError(t, err)

	resp, err := tr.RoundTripOpt(req, http3.RoundTripOpt{})
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, firstConn.LocalAddr().String(), string(body))

	firstConn.StartBlocking()
	// wait for the connection to time out
	select {
	case c := <-connChan:
		select {
		case <-c.Context().Done():
		case <-time.After(time.Second):
			t.Fatal("connection did not time out")
		}
	case <-time.After(time.Second):
		t.Fatal("no connection was created")
	}

	// second request should succeed after re-dialing
	resp, err = tr.RoundTripOpt(req, http3.RoundTripOpt{OnlyCachedConn: onlyCachedConn})
	if onlyCachedConn {
		require.EqualError(t, err, "http3: no cached connection was available")
		require.Len(t, conns, 1) // no second dial attempt
		require.Equal(t, 1, headersCount)
		return
	}
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	body, err = io.ReadAll(&readerWithTimeout{Reader: resp.Body, Timeout: 2 * time.Second})
	require.NoError(t, err)
	require.Equal(t, secondConn.LocalAddr().String(), string(body))

	require.Equal(t, 2, headersCount)
	require.Empty(t, conns) // make sure we dialed 2 connections
}

func TestHTTPRequestAfterGracefulShutdown(t *testing.T) {
	t.Run("Request.GetBody set", func(t *testing.T) {
		testHTTPRequestAfterGracefulShutdown(t, true)
	})
	t.Run("Request.GetBody not set", func(t *testing.T) {
		testHTTPRequestAfterGracefulShutdown(t, false)
	})
}

func testHTTPRequestAfterGracefulShutdown(t *testing.T, setGetBody bool) {
	t.Setenv("QUIC_GO_DISABLE_RECEIVE_BUFFER_WARNING", "true")

	ln, err := quic.ListenEarly(
		newUDPConnLocalhost(t),
		http3.ConfigureTLSConfig(getTLSConfig()),
		getQuicConfig(nil),
	)
	require.NoError(t, err)

	var inShutdown atomic.Bool
	proxy := quicproxy.Proxy{
		Conn:       newUDPConnLocalhost(t),
		ServerAddr: ln.Addr().(*net.UDPAddr),
		DelayPacket: func(_ quicproxy.Direction, _, _ net.Addr, data []byte) time.Duration {
			if inShutdown.Load() {
				return scaleDuration(10 * time.Millisecond)
			}
			return scaleDuration(2 * time.Millisecond)
		},
	}
	require.NoError(t, proxy.Start())
	defer proxy.Close()

	mux2 := http.NewServeMux()
	mux2.HandleFunc("/echo", func(w http.ResponseWriter, r *http.Request) {
		data, _ := io.ReadAll(r.Body)
		w.Write(data)
	})
	server2 := &http3.Server{Handler: mux2}

	done := make(chan struct{})
	defer close(done)
	server1 := &http3.Server{Handler: http.NewServeMux()}

	go server1.ServeListener(ln)

	tlsConf := getTLSClientConfigWithoutServerName()
	tlsConf.NextProtos = []string{http3.NextProtoH3}
	var dialCount int
	tr := &http3.Transport{
		TLSClientConfig: tlsConf,
		Dial: func(ctx context.Context, a string, tlsConf *tls.Config, conf *quic.Config) (*quic.Conn, error) {
			addr, err := net.ResolveUDPAddr("udp", a)
			if err != nil {
				return nil, err
			}
			dialCount++
			return quic.DialEarly(ctx, newUDPConnLocalhost(t), addr, tlsConf, conf)
		},
	}
	t.Cleanup(func() { tr.Close() })
	cl := &http.Client{Transport: tr}

	// first request to establish the connection
	resp, err := cl.Get(fmt.Sprintf("https://%s/", proxy.LocalAddr()))
	require.NoError(t, err)
	require.Equal(t, http.StatusNotFound, resp.StatusCode)

	// If the body is a strings.Reader, http.NewRequest automatically sets the GetBody callback.
	// This can be prevented by using a different kind of reader, e.g. the io.LimitReader.
	var headersCount int
	req, err := http.NewRequestWithContext(
		httptrace.WithClientTrace(context.Background(), &httptrace.ClientTrace{
			WroteHeaders: func() { headersCount++ },
		}),
		http.MethodGet,
		fmt.Sprintf("https://%s/echo", proxy.LocalAddr()),
		io.LimitReader(strings.NewReader("foobar"), 1000),
	)
	require.NoError(t, err)
	if setGetBody {
		req.GetBody = func() (io.ReadCloser, error) {
			return io.NopCloser(strings.NewReader("foobaz")), nil
		}
	} else {
		require.Nil(t, req.GetBody)
	}

	// By increasing the RTT, we make sure that the request is sent before the client receives the GOAWAY frame.
	inShutdown.Store(true)
	go server1.Shutdown(context.Background())
	go server2.ServeListener(ln)
	defer server2.Close()

	resp, err = cl.Do(req)
	if !setGetBody {
		require.ErrorContains(t, err, "after Request.Body was written; define Request.GetBody to avoid this error")
		require.Equal(t, 1, dialCount)
		require.Equal(t, 1, headersCount)
		return
	}
	require.NoError(t, err)
	require.Equal(t, http.StatusOK, resp.StatusCode)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "foobaz", string(body))
	require.Equal(t, 2, dialCount)
	require.Equal(t, 2, headersCount)
}