Repository: go
Issue: net/http: error dropped when header read times out
Labels: NeedsInvestigation

<!--
Please answer these questions before submitting your issue. Thanks!
-->

### What version of Go are you using (`go version`)?

<pre>
$ go version
go version go1.19 linux/amd64
</pre>

### Does this issue reproduce with the latest release?

Yes

### What operating system and processor architecture are you using (`go env`)?

<details><summary><code>go env</code> Output</summary><br><pre>
$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/work/.cache/go-build"
GOENV="/home/work/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/work/gopath/pkg/mod"
GONOPROXY=""
GONOSUMDB="*"
GOOS="linux"
GOPATH="/home/work/gopath"
GOPRIVATE=""
GOPROXY=""
GOROOT="/home/work/gopath/src/go-env/go1-19-linux-amd64"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/work/gopath/src/go-env/go1-19-linux-amd64/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.19"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="/opt/compiler/gcc-8.2/bin/gcc"
CXX="/opt/compiler/gcc-8.2/bin/g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3130045008=/tmp/go-build -gno-record-gcc-switches"
</pre></details>

### What did you do?

<!--
If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on go.dev/play is best.
-->

```
package main

import (
	"context"
	"fmt"
	"log"
	"net"
	"net/http"
	"os"
	"time"
)

type handler struct {
}

func (h *handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	w.Write([]byte("Hello World"))
}

func newServer(port int) *http.Server {
	s := &http.Server{
		Addr:           fmt.Sprintf(":%d", port),
		Handler:        &handler{},
		ReadTimeout:    100 * time.Millisecond,
		WriteTimeout:   100 * time.Millisecond,
		MaxHeaderBytes: 1 << 20,
		ErrorLog:       log.New(os.Stderr, "", log.LstdFlags),
	}
	return s
}

func send(port int) {
	conn, err := net.Dial("tcp", fmt.Sprintf("127.0.0.1:%d", port))
	if err != nil {
		fmt.Println(err)
		return
	}

	n, e := conn.Write([]byte("GET / HTTP/1.1\r\n"))
	fmt.Println("send first line", n, e)

	n, e = conn.Write([]byte("Host: www.google.com\r\n"))
	fmt.Println("send host", n, e)

	n, e = conn.Write([]byte("Host1"))
	fmt.Println("send part header", n, e)

	// more than ReadTimeout
	time.Sleep(time.Millisecond * 110)

	buf := make([]byte, 8192)
	n, e = conn.Read(buf)
	fmt.Println("read resp", n, e)
	fmt.Println("print resp", "`"+string(buf)+"`")
	time.Sleep(time.Millisecond * 200)
	fmt.Println("conn close", conn.Close())
}

func main() {
	port := 12101
	svr := newServer(port)
	go func() {
		fmt.Println(svr.ListenAndServe())
	}()

	// wait server start
	time.Sleep(time.Second * 1)
	go send(port)

	time.Sleep(time.Second * 1)
	fmt.Println("server shutdown", svr.Shutdown(context.Background()))
	time.Sleep(time.Second * 1)
}

```



### What did you expect to see?

```
send first line 16 <nil>
send host 22 <nil>
send part header 5 <nil>
read resp 0 EOF
print resp ``
conn close <nil>
http: Server closed
server shutdown <nil>
```

and log `read tcp 127.0.0.1:12101->127.0.0.1:xxx: i/o timeout`





### What did you see instead?

```
send first line 16 <nil>
send host 22 <nil>
send part header 5 <nil>
read resp 103 <nil>
print resp `HTTP/1.1 400 Bad Request
Content-Type: text/plain; charset=utf-8
Connection: close

400 Bad Request`
conn close <nil>
http: Server closed
server shutdown <nil>
```

***Because 'bufio. ReadLine()' dropped the error, causing http.server to return '400 Bad Request'***