net/http: don't send implicit Content-Length if Transfer-Encoding is set

Fixes golang#9987 Change-Id: Ibebd105a2bcdc1741f3b41aa78cb986f3f518b53 Reviewed-on: https://go-review.googlesource.com/9638 Reviewed-by: Andrew Gerrand <[email protected]> Run-TryBot: Brad Fitzpatrick <[email protected]>
weswigham · May 6, 2015 · c661cb0 · c661cb0
1 parent 62fb472
commit c661cb0
Show file tree

Hide file tree

Showing 2 changed files with 44 additions and 4 deletions.
diff --git a/src/net/http/serve_test.go b/src/net/http/serve_test.go
@@ -2767,6 +2767,43 @@ func TestServerKeepAliveAfterWriteError(t *testing.T) {
 	}
 }
 
+// Issue 9987: shouldn't add automatic Content-Length (or
+// Content-Type) if a Transfer-Encoding was set by the handler.
+func TestNoContentLengthIfTransferEncoding(t *testing.T) {
+	defer afterTest(t)
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		w.Header().Set("Transfer-Encoding", "foo")
+		io.WriteString(w, "<html>")
+	}))
+	defer ts.Close()
+	c, err := net.Dial("tcp", ts.Listener.Addr().String())
+	if err != nil {
+		t.Fatalf("Dial: %v", err)
+	}
+	defer c.Close()
+	if _, err := io.WriteString(c, "GET / HTTP/1.1\r\nHost: foo\r\n\r\n"); err != nil {
+		t.Fatal(err)
+	}
+	bs := bufio.NewScanner(c)
+	var got bytes.Buffer
+	for bs.Scan() {
+		if strings.TrimSpace(bs.Text()) == "" {
+			break
+		}
+		got.WriteString(bs.Text())
+		got.WriteByte('\n')
+	}
+	if err := bs.Err(); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(got.String(), "Content-Length") {
+		t.Errorf("Unexpected Content-Length in response headers: %s", got.String())
+	}
+	if strings.Contains(got.String(), "Content-Type") {
+		t.Errorf("Unexpected Content-Type in response headers: %s", got.String())
+	}
+}
+
 func BenchmarkClientServer(b *testing.B) {
 	b.ReportAllocs()
 	b.StopTimer()

diff --git a/src/net/http/server.go b/src/net/http/server.go
@@ -781,6 +781,9 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 		foreachHeaderElement(v, cw.res.declareTrailer)
 	}
 
+	te := header.get("Transfer-Encoding")
+	hasTE := te != ""
+
 	// If the handler is done but never sent a Content-Length
 	// response header and this is our first (and last) write, set
 	// it, even to zero. This helps HTTP/1.0 clients keep their
@@ -793,7 +796,9 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 	// write non-zero bytes.  If it's actually 0 bytes and the
 	// handler never looked at the Request.Method, we just don't
 	// send a Content-Length header.
-	if w.handlerDone && !trailers && bodyAllowedForStatus(w.status) && header.get("Content-Length") == "" && (!isHEAD || len(p) > 0) {
+	// Further, we don't send an automatic Content-Length if they
+	// set a Transfer-Encoding, because they're generally incompatible.
+	if w.handlerDone && !trailers && !hasTE && bodyAllowedForStatus(w.status) && header.get("Content-Length") == "" && (!isHEAD || len(p) > 0) {
 		w.contentLength = int64(len(p))
 		setHeader.contentLength = strconv.AppendInt(cw.res.clenBuf[:0], int64(len(p)), 10)
 	}
@@ -845,7 +850,7 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 	if bodyAllowedForStatus(code) {
 		// If no content type, apply sniffing algorithm to body.
 		_, haveType := header["Content-Type"]
-		if !haveType {
+		if !haveType && !hasTE {
 			setHeader.contentType = DetectContentType(p)
 		}
 	} else {
@@ -858,8 +863,6 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 		setHeader.date = appendTime(cw.res.dateBuf[:0], time.Now())
 	}
 
-	te := header.get("Transfer-Encoding")
-	hasTE := te != ""
 	if hasCL && hasTE && te != "identity" {
 		// TODO: return an error if WriteHeader gets a return parameter
 		// For now just ignore the Content-Length.