net/http: allow Handlers to test Hijacked conn without spamming error log

Make a zero-byte write to a hijacked connection not log anything, so handlers
can test whether a connection is hacked by doing a Write(nil).

Fixes #16456

Change-Id: Id56caf822c8592067bd8422672f0c1aec89e866c
Reviewed-on: https://go-review.googlesource.com/30812
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>

diff --git a/src/net/http/serve_test.go b/src/net/http/serve_test.go
index 360d3a37b39043d6c459b3b2446cbebee5b7b533..db72e70e358731c7ecb2cfe81d5f4d2959495ccd 100644 (file)
--- a/src/net/http/serve_test.go
+++ b/src/net/http/serve_test.go
@@ -2252,6 +2252,51 @@ func testHandlerPanic(t *testing.T, withHijack, h2 bool, panicValue interface{})
        }
 }
 
+type terrorWriter struct{ t *testing.T }
+
+func (w terrorWriter) Write(p []byte) (int, error) {
+       w.t.Errorf("%s", p)
+       return len(p), nil
+}
+
+// Issue 16456: allow writing 0 bytes on hijacked conn to test hijack
+// without any log spam.
+func TestServerWriteHijackZeroBytes(t *testing.T) {
+       defer afterTest(t)
+       done := make(chan struct{})
+       ts := httptest.NewUnstartedServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+               defer close(done)
+               w.(Flusher).Flush()
+               conn, _, err := w.(Hijacker).Hijack()
+               if err != nil {
+                       t.Errorf("Hijack: %v", err)
+                       return
+               }
+               defer conn.Close()
+               _, err = w.Write(nil)
+               if err != ErrHijacked {
+                       t.Errorf("Write error = %v; want ErrHijacked", err)
+               }
+       }))
+       ts.Config.ErrorLog = log.New(terrorWriter{t}, "Unexpected write: ", 0)
+       ts.Start()
+       defer ts.Close()
+
+       tr := &Transport{}
+       defer tr.CloseIdleConnections()
+       c := &Client{Transport: tr}
+       res, err := c.Get(ts.URL)
+       if err != nil {
+               t.Fatal(err)
+       }
+       res.Body.Close()
+       select {
+       case <-done:
+       case <-time.After(5 * time.Second):
+               t.Fatal("timeout")
+       }
+}
+
 func TestServerNoDate_h1(t *testing.T)        { testServerNoHeader(t, h1Mode, "Date") }
 func TestServerNoDate_h2(t *testing.T)        { testServerNoHeader(t, h2Mode, "Date") }
 func TestServerNoContentType_h1(t *testing.T) { testServerNoHeader(t, h1Mode, "Content-Type") }

diff --git a/src/net/http/server.go b/src/net/http/server.go
index 2677468aa31489aff3feb70ad15d49957bc2bfdb..d71006441eb766fdccd9ab80b68d909d836a5891 100644 (file)
--- a/src/net/http/server.go
+++ b/src/net/http/server.go
@@ -1318,7 +1318,9 @@ func (w *response) WriteString(data string) (n int, err error) {
 // either dataB or dataS is non-zero.
 func (w *response) write(lenData int, dataB []byte, dataS string) (n int, err error) {
        if w.conn.hijacked() {
-               w.conn.server.logf("http: response.Write on hijacked connection")
+               if lenData > 0 {
+                       w.conn.server.logf("http: response.Write on hijacked connection")
+               }
                return 0, ErrHijacked
        }
        if !w.wroteHeader {