net/http: Transport.CancelRequest no longer cancels in-flight request #40453
Description
(*net/http.Transport).CancelRequest's documentation states:
CancelRequest should only be called after RoundTrip has returned.
Despite this warning, CancelRequest does usually cancel an in-flight request currently blocked in RoundTrip. CL 234894 has inadvertently broken this for requests with a body.
Crude reproduction case follows.
package main
import (
"bytes"
"fmt"
"net/http"
"testing"
"time"
)
func init() {
http.HandleFunc("/ok", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintln(w, "ok")
})
http.HandleFunc("/hang", func(w http.ResponseWriter, r *http.Request) {
<-r.Context().Done()
})
go http.ListenAndServe("localhost:8080", nil)
}
func TestHTTP(t *testing.T) {
for {
_, err := http.Get("http://localhost:8080/ok")
if err == nil {
break
}
}
buf := bytes.NewBuffer([]byte{1, 2, 3})
req, err := http.NewRequest("GET", "http://localhost:8080/hang", buf)
if err != nil {
t.Fatal(err)
}
donec := make(chan int)
go func() {
defer close(donec)
http.DefaultTransport.RoundTrip(req)
}()
time.Sleep(100 * time.Millisecond)
http.DefaultTransport.(*http.Transport).CancelRequest(req)
<-donec
}