diff --git a/http3/response_writer.go b/http3/response_writer.go index 06204615..5cc32923 100644 --- a/http3/response_writer.go +++ b/http3/response_writer.go @@ -80,10 +80,26 @@ func (w *responseWriter) WriteHeader(status int) { } func (w *responseWriter) Write(p []byte) (int, error) { + bodyAllowed := bodyAllowedForStatus(w.status) if !w.headerWritten { + // If body is not allowed, we don't need to (and we can't) sniff the content type. + if bodyAllowed { + // If no content type, apply sniffing algorithm to body. + // We can't use `w.header.Get` here since if the Content-Type was set to nil, we shoundn't do sniffing. + _, haveType := w.header["Content-Type"] + + // If the Transfer-Encoding or Content-Encoding was set and is non-blank, + // we shouldn't sniff the body. + hasTE := w.header.Get("Transfer-Encoding") != "" + hasCE := w.header.Get("Content-Encoding") != "" + if !hasCE && !haveType && !hasTE && len(p) > 0 { + w.header.Set("Content-Type", http.DetectContentType(p)) + } + } w.WriteHeader(http.StatusOK) + bodyAllowed = true } - if !bodyAllowedForStatus(w.status) { + if !bodyAllowed { return 0, http.ErrBodyNotAllowed } df := &dataFrame{Length: uint64(len(p))} diff --git a/http3/response_writer_test.go b/http3/response_writer_test.go index f27560fd..7644913a 100644 --- a/http3/response_writer_test.go +++ b/http3/response_writer_test.go @@ -147,4 +147,13 @@ var _ = Describe("Response Writer", func() { Expect(n).To(BeZero()) Expect(err).To(MatchError(http.ErrBodyNotAllowed)) }) + + It("first call to Write sniffs if Content-Type is not set", func() { + n, err := rw.Write([]byte("")) + Expect(n).To(Equal(13)) + Expect(err).ToNot(HaveOccurred()) + + fields := decodeHeader(strBuf) + Expect(fields).To(HaveKeyWithValue("content-type", []string{"text/html; charset=utf-8"})) + }) })