http: handle status 304 correctly

  - cannot send body
  - should not send body-related headers

R=r
CC=golang-dev
https://golang.org/cl/1499041

diff --git a/src/pkg/http/server.go b/src/pkg/http/server.go
index a28eb25ee4a60a16a66393f08f2caad75eec9363..9f0bc660878750a3605135e383244edbfd93d356 100644 (file)
--- a/src/pkg/http/server.go
+++ b/src/pkg/http/server.go
@@ -26,6 +26,7 @@ import (
 // Errors introduced by the HTTP server.
 var (
        ErrWriteAfterFlush = os.NewError("Conn.Write called after Flush")
+       ErrBodyNotAllowed  = os.NewError("http: response status code does not allow body")
        ErrHijacked        = os.NewError("Conn has been hijacked")
 )
 
@@ -138,6 +139,11 @@ func (c *Conn) WriteHeader(code int) {
        }
        c.wroteHeader = true
        c.status = code
+       if code == StatusNotModified {
+               // Must not have body.
+               c.header["Content-Type"] = "", false
+               c.header["Transfer-Encoding"] = "", false
+       }
        c.written = 0
        if !c.Req.ProtoAtLeast(1, 0) {
                return
@@ -173,6 +179,11 @@ func (c *Conn) Write(data []byte) (n int, err os.Error) {
                return 0, nil
        }
 
+       if c.status == StatusNotModified {
+               // Must not have body.
+               return 0, ErrBodyNotAllowed
+       }
+
        c.written += int64(len(data)) // ignoring errors, for errorKludge
 
        // TODO(rsc): if chunking happened after the buffering,