From acc2957bc9873ab7e65942045830a3dc0592eda2 Mon Sep 17 00:00:00 2001 From: Damien Neil Date: Thu, 5 Aug 2021 19:26:21 -0700 Subject: [PATCH] net/http: fix hang in probing for a zero-length request body Fix a hang that occurs when making a request and all of the following apply: * The request method is one of GET, HEAD, DELETE, OPTIONS, PROPFIND, or SEARCH. * The Request.Body is non-nil. * The content length is not set, or is set to -1. * Transfer-Encoding: chunked is not set. * The request body does not respond to a read within 200ms. In this case, we give up on probing for a zero-length body and send the request while the probe completes in the background. Fix a bug in the io.Reader wrapping the in-flight probe: It should return io.EOF after the probe completes, but does not. Fixes #47568. Change-Id: I7f9188c96e1210055df68424081af927006e4816 Reviewed-on: https://go-review.googlesource.com/c/go/+/340256 Trust: Damien Neil Run-TryBot: Damien Neil TryBot-Result: Go Bot Reviewed-by: Ingo Oeser Reviewed-by: Brad Fitzpatrick --- src/net/http/client_test.go | 44 +++++++++++++++++++++++++++++++++++++ src/net/http/transfer.go | 4 ++++ 2 files changed, 48 insertions(+) diff --git a/src/net/http/client_test.go b/src/net/http/client_test.go index 01d605c351..05ed2268b5 100644 --- a/src/net/http/client_test.go +++ b/src/net/http/client_test.go @@ -2082,3 +2082,47 @@ func (b *issue40382Body) Close() error { } return nil } + +func TestProbeZeroLengthBody(t *testing.T) { + setParallel(t) + defer afterTest(t) + reqc := make(chan struct{}) + cst := newClientServerTest(t, false, HandlerFunc(func(w ResponseWriter, r *Request) { + close(reqc) + if _, err := io.Copy(w, r.Body); err != nil { + t.Errorf("error copying request body: %v", err) + } + })) + defer cst.close() + + bodyr, bodyw := io.Pipe() + var gotBody string + var wg sync.WaitGroup + wg.Add(1) + go func() { + defer wg.Done() + req, _ := NewRequest("GET", cst.ts.URL, bodyr) + res, err := cst.c.Do(req) + b, err := io.ReadAll(res.Body) + if err != nil { + t.Error(err) + } + gotBody = string(b) + }() + + select { + case <-reqc: + // Request should be sent after trying to probe the request body for 200ms. + case <-time.After(60 * time.Second): + t.Errorf("request not sent after 60s") + } + + // Write the request body and wait for the request to complete. + const content = "body" + bodyw.Write([]byte(content)) + bodyw.Close() + wg.Wait() + if gotBody != content { + t.Fatalf("server got body %q, want %q", gotBody, content) + } +} diff --git a/src/net/http/transfer.go b/src/net/http/transfer.go index 85c2e5a360..5ff89cc17f 100644 --- a/src/net/http/transfer.go +++ b/src/net/http/transfer.go @@ -212,6 +212,7 @@ func (t *transferWriter) probeRequestBody() { rres.b = buf[0] } t.ByteReadCh <- rres + close(t.ByteReadCh) }(t.Body) timer := time.NewTimer(200 * time.Millisecond) select { @@ -1072,6 +1073,9 @@ func (fr finishAsyncByteRead) Read(p []byte) (n int, err error) { if n == 1 { p[0] = rres.b } + if err == nil { + err = io.EOF + } return } -- 2.48.1