net/http/pprof: durationExceedsWriteTimeout check doesn't consider ResponseController.SetWriteDeadline

[sentriz]

Go version

go version go1.21.4 linux/amd64

What operating system and processor architecture are you using (go env)?

$ go env

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/senan/.cache/go-build'
GOENV='/home/senan/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/senan/.local/share/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/senan/.local/share/go'
GOPRIVATE=''
GOPROXY='direct'
GOROOT='/usr/lib/go'
GOSUMDB='off'
GOTMPDIR=''
GOTOOLCHAIN='local+path'
GOTOOLDIR='/usr/lib/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.4'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1962473061=/tmp/go-build -gno-record-gcc-switches'

What did you do?

curling the following program with

curl "http://localhost:8080/debug/pprof/profile?seconds=10"

(10 seconds being longer than the 1 second global WriteTimeout, but before than the deadline set by SetWriteDeadline)

https://go.dev/play/p/zWTDhWFutKP

package main

import (
	"fmt"
	"net/http"
	"net/http/pprof"
	"time"
)

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/debug/pprof/profile", func(w http.ResponseWriter, r *http.Request) {
		rc := http.NewResponseController(w)
		rc.SetWriteDeadline(time.Time{}) // no deadline
		pprof.Profile(w, r)
	})

	server := http.Server{
		Addr:         ":8080",
		WriteTimeout: 1 * time.Second, // 1 second timeout
		Handler:      mux,
	}

	fmt.Println(server.ListenAndServe())
}

What did you expect to see?

the request succeeds

What did you see instead?

HTTP 400 with "profile duration exceeds server's WriteTimeout"

this makes it hard to expose custom pprof handlers with global server write timeouts

[seankhliao]

Duplicate of #62358