http: change ResponseWriter.SetHeader(k,v) to Header() accessor

Caller code needs to change:

rw.SetHeader("Content-Type", "text/plain")
to:
rw.Header().Set("Content-Type", "text/plain")

This now permits returning multiple headers
with the same name using Add:

rw.Header().Add("Set-Cookie", "..")
rw.Header().Add("Set-Cookie", "..")

This patch also fixes serialization of headers, removing newline characters.

Fixes #488
Fixes #914

R=rsc
CC=gburd, golang-dev
https://golang.org/cl/4239076

src/cmd/godoc/godoc.go

@@ -702,7 +702,7 @@ func servePage(w http.ResponseWriter, title, subtitle, query string, content []b
 
 
 func serveText(w http.ResponseWriter, text []byte) {
-	w.SetHeader("Content-Type", "text/plain; charset=utf-8")
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 	w.Write(text)
 }
 

src/cmd/godoc/main.go

@@ -111,7 +111,7 @@ func exec(rw http.ResponseWriter, args []string) (status int) {
 		os.Stderr.Write(buf.Bytes())
 	}
 	if rw != nil {
-		rw.SetHeader("content-type", "text/plain; charset=utf-8")
+		rw.Header().Set("Content-Type", "text/plain; charset=utf-8")
 		rw.Write(buf.Bytes())
 	}
 

src/pkg/expvar/expvar.go

@@ -269,7 +269,7 @@ func Iter() <-chan KeyValue {
 }
 
 func expvarHandler(w http.ResponseWriter, r *http.Request) {
-	w.SetHeader("content-type", "application/json; charset=utf-8")
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	fmt.Fprintf(w, "{\n")
 	first := true
 	for name, value := range vars {

src/pkg/http/cgi/child.go

@@ -149,12 +149,8 @@ func (r *response) RemoteAddr() string {
 	return os.Getenv("REMOTE_ADDR")
 }
 
-func (r *response) SetHeader(k, v string) {
+func (r *response) Header() http.Header {
-	if v == "" {
+	return r.header
-		r.header.Del(k)
-	} else {
-		r.header.Set(k, v)
-	}
 }
 
 func (r *response) Write(p []byte) (n int, err os.Error) {

src/pkg/http/cgi/host.go

@@ -139,7 +139,7 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	}
 
 	linebody := line.NewReader(cmd.Stdout, 1024)
-	headers := make(map[string]string)
+	headers := rw.Header()
 	statusCode := http.StatusOK
 	for {
 		line, isPrefix, err := linebody.ReadLine()
@@ -181,12 +181,9 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 			}
 			statusCode = code
 		default:
-			headers[header] = val
+			headers.Add(header, val)
 		}
 	}
-	for h, v := range headers {
-		rw.SetHeader(h, v)
-	}
 	rw.WriteHeader(statusCode)
 
 	_, err = io.Copy(rw, linebody)

src/pkg/http/cgi/host_test.go

@@ -111,10 +111,10 @@ func TestCGIBasicGet(t *testing.T) {
 	}
 	replay := runCgiTest(t, h, "GET /test.cgi?foo=bar&a=b HTTP/1.0\nHost: example.com\n\n", expectedMap)
 
-	if expected, got := "text/html", replay.Header.Get("Content-Type"); got != expected {
+	if expected, got := "text/html", replay.Header().Get("Content-Type"); got != expected {
 		t.Errorf("got a Content-Type of %q; expected %q", got, expected)
 	}
-	if expected, got := "X-Test-Value", replay.Header.Get("X-Test-Header"); got != expected {
+	if expected, got := "X-Test-Value", replay.Header().Get("X-Test-Header"); got != expected {
 		t.Errorf("got a X-Test-Header of %q; expected %q", got, expected)
 	}
 }

src/pkg/http/cgi/matryoshka_test.go

@@ -43,10 +43,10 @@ func TestHostingOurselves(t *testing.T) {
 	}
 	replay := runCgiTest(t, h, "GET /test.go?foo=bar&a=b HTTP/1.0\nHost: example.com\n\n", expectedMap)
 
-	if expected, got := "text/html; charset=utf-8", replay.Header.Get("Content-Type"); got != expected {
+	if expected, got := "text/html; charset=utf-8", replay.Header().Get("Content-Type"); got != expected {
 		t.Errorf("got a Content-Type of %q; expected %q", got, expected)
 	}
-	if expected, got := "X-Test-Value", replay.Header.Get("X-Test-Header"); got != expected {
+	if expected, got := "X-Test-Value", replay.Header().Get("X-Test-Header"); got != expected {
 		t.Errorf("got a X-Test-Header of %q; expected %q", got, expected)
 	}
 }
@@ -58,7 +58,7 @@ func TestBeChildCGIProcess(t *testing.T) {
 		return
 	}
 	Serve(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
-		rw.SetHeader("X-Test-Header", "X-Test-Value")
+		rw.Header().Set("X-Test-Header", "X-Test-Value")
 		fmt.Fprintf(rw, "test=Hello CGI-in-CGI\n")
 		req.ParseForm()
 		for k, vv := range req.Form {

src/pkg/http/fs.go

@@ -108,7 +108,7 @@ func serveFile(w ResponseWriter, r *Request, name string, redirect bool) {
 		w.WriteHeader(StatusNotModified)
 		return
 	}
-	w.SetHeader("Last-Modified", time.SecondsToUTC(d.Mtime_ns/1e9).Format(TimeFormat))
+	w.Header().Set("Last-Modified", time.SecondsToUTC(d.Mtime_ns/1e9).Format(TimeFormat))
 
 	// use contents of index.html for directory, if present
 	if d.IsDirectory() {
@@ -137,16 +137,16 @@ func serveFile(w ResponseWriter, r *Request, name string, redirect bool) {
 	// use extension to find content type.
 	ext := filepath.Ext(name)
 	if ctype := mime.TypeByExtension(ext); ctype != "" {
-		w.SetHeader("Content-Type", ctype)
+		w.Header().Set("Content-Type", ctype)
 	} else {
 		// read first chunk to decide between utf-8 text and binary
 		var buf [1024]byte
 		n, _ := io.ReadFull(f, buf[:])
 		b := buf[:n]
 		if isText(b) {
-			w.SetHeader("Content-Type", "text-plain; charset=utf-8")
+			w.Header().Set("Content-Type", "text-plain; charset=utf-8")
 		} else {
-			w.SetHeader("Content-Type", "application/octet-stream") // generic binary
+			w.Header().Set("Content-Type", "application/octet-stream") // generic binary
 		}
 		f.Seek(0, 0) // rewind to output whole file
 	}
@@ -166,11 +166,11 @@ func serveFile(w ResponseWriter, r *Request, name string, redirect bool) {
 		}
 		size = ra.length
 		code = StatusPartialContent
-		w.SetHeader("Content-Range", fmt.Sprintf("bytes %d-%d/%d", ra.start, ra.start+ra.length-1, d.Size))
+		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", ra.start, ra.start+ra.length-1, d.Size))
 	}
 
-	w.SetHeader("Accept-Ranges", "bytes")
+	w.Header().Set("Accept-Ranges", "bytes")
-	w.SetHeader("Content-Length", strconv.Itoa64(size))
+	w.Header().Set("Content-Length", strconv.Itoa64(size))
 
 	w.WriteHeader(code)
 

src/pkg/http/httptest/recorder.go

@@ -15,10 +15,9 @@ import (
 // records its mutations for later inspection in tests.
 type ResponseRecorder struct {
 	Code           int           // the HTTP response code from WriteHeader
-	Header  http.Header   // if non-nil, the headers to populate
+	HeaderMap      http.Header   // the HTTP response headers
 	Body           *bytes.Buffer // if non-nil, the bytes.Buffer to append written data to
 	Flushed        bool
-
 	FakeRemoteAddr string // the fake RemoteAddr to return, or "" for DefaultRemoteAddr
 	FakeUsingTLS   bool   // whether to return true from the UsingTLS method
 }
@@ -26,7 +25,7 @@ type ResponseRecorder struct {
 // NewRecorder returns an initialized ResponseRecorder.
 func NewRecorder() *ResponseRecorder {
 	return &ResponseRecorder{
-		Header: http.Header(make(map[string][]string)),
+		HeaderMap: make(http.Header),
 		Body:      new(bytes.Buffer),
 	}
 }
@@ -49,15 +48,9 @@ func (rw *ResponseRecorder) UsingTLS() bool {
 	return rw.FakeUsingTLS
 }
 
-// SetHeader populates rw.Header, if non-nil.
+// Header returns the response headers.
-func (rw *ResponseRecorder) SetHeader(k, v string) {
+func (rw *ResponseRecorder) Header() http.Header {
-	if rw.Header != nil {
+	return rw.HeaderMap
-		if v == "" {
-			rw.Header.Del(k)
-		} else {
-			rw.Header.Set(k, v)
-		}
-	}
 }
 
 // Write always succeeds and writes to rw.Body, if not nil.

src/pkg/http/pprof/pprof.go

@@ -41,14 +41,14 @@ func init() {
 // command line, with arguments separated by NUL bytes.
 // The package initialization registers it as /debug/pprof/cmdline.
 func Cmdline(w http.ResponseWriter, r *http.Request) {
-	w.SetHeader("content-type", "text/plain; charset=utf-8")
+	w.Header().Set("content-type", "text/plain; charset=utf-8")
 	fmt.Fprintf(w, strings.Join(os.Args, "\x00"))
 }
 
 // Heap responds with the pprof-formatted heap profile.
 // The package initialization registers it as /debug/pprof/heap.
 func Heap(w http.ResponseWriter, r *http.Request) {
-	w.SetHeader("content-type", "text/plain; charset=utf-8")
+	w.Header().Set("content-type", "text/plain; charset=utf-8")
 	pprof.WriteHeapProfile(w)
 }
 
@@ -56,7 +56,7 @@ func Heap(w http.ResponseWriter, r *http.Request) {
 // responding with a table mapping program counters to function names.
 // The package initialization registers it as /debug/pprof/symbol.
 func Symbol(w http.ResponseWriter, r *http.Request) {
-	w.SetHeader("content-type", "text/plain; charset=utf-8")
+	w.Header().Set("content-type", "text/plain; charset=utf-8")
 
 	// We don't know how many symbols we have, but we
 	// do have symbol information.  Pprof only cares whether

src/pkg/http/response.go

@@ -217,13 +217,16 @@ func (resp *Response) Write(w io.Writer) os.Error {
 func writeSortedHeader(w io.Writer, h Header, exclude map[string]bool) os.Error {
 	keys := make([]string, 0, len(h))
 	for k := range h {
-		if !exclude[k] {
+		if exclude == nil || !exclude[k] {
 			keys = append(keys, k)
 		}
 	}
 	sort.SortStrings(keys)
 	for _, k := range keys {
 		for _, v := range h[k] {
+			v = strings.TrimSpace(v)
+			v = strings.Replace(v, "\n", " ", -1)
+			v = strings.Replace(v, "\r", " ", -1)
 			if _, err := fmt.Fprintf(w, "%s: %s\r\n", k, v); err != nil {
 				return err
 			}

src/pkg/http/responsewrite_test.go

@@ -65,6 +65,29 @@ var respWriteTests = []respWriteTest{
 			"Transfer-Encoding: chunked\r\n\r\n" +
 			"6\r\nabcdef\r\n0\r\n\r\n",
 	},
+
+	// Header value with a newline character (Issue 914).
+	// Also tests removal of leading and trailing whitespace.
+	{
+		Response{
+			StatusCode:    204,
+			ProtoMajor:    1,
+			ProtoMinor:    1,
+			RequestMethod: "GET",
+			Header: Header{
+				"Foo": []string{" Bar\nBaz "},
+			},
+			Body:             nil,
+			ContentLength:    0,
+			TransferEncoding: []string{"chunked"},
+			Close:            true,
+		},
+
+		"HTTP/1.1 204 No Content\r\n" +
+			"Connection: close\r\n" +
+			"Foo: Bar Baz\r\n" +
+			"\r\n",
+	},
 }
 
 func TestResponseWrite(t *testing.T) {
@@ -78,7 +101,7 @@ func TestResponseWrite(t *testing.T) {
 		}
 		sraw := braw.String()
 		if sraw != tt.Raw {
-			t.Errorf("Test %d, expecting:\n%s\nGot:\n%s\n", i, tt.Raw, sraw)
+			t.Errorf("Test %d, expecting:\n%q\nGot:\n%q\n", i, tt.Raw, sraw)
 			continue
 		}
 	}

src/pkg/http/serve_test.go

@@ -144,7 +144,7 @@ func TestConsumingBodyOnNextConn(t *testing.T) {
 type stringHandler string
 
 func (s stringHandler) ServeHTTP(w ResponseWriter, r *Request) {
-	w.SetHeader("Result", string(s))
+	w.Header().Set("Result", string(s))
 }
 
 var handlers = []struct {
@@ -216,7 +216,7 @@ func TestMuxRedirectLeadingSlashes(t *testing.T) {
 
 		mux.ServeHTTP(resp, req)
 
-		if loc, expected := resp.Header.Get("Location"), "/foo.txt"; loc != expected {
+		if loc, expected := resp.Header().Get("Location"), "/foo.txt"; loc != expected {
 			t.Errorf("Expected Location header set to %q; got %q", expected, loc)
 			return
 		}
@@ -294,8 +294,8 @@ func TestServerTimeouts(t *testing.T) {
 // TestIdentityResponse verifies that a handler can unset 
 func TestIdentityResponse(t *testing.T) {
 	handler := HandlerFunc(func(rw ResponseWriter, req *Request) {
-		rw.SetHeader("Content-Length", "3")
+		rw.Header().Set("Content-Length", "3")
-		rw.SetHeader("Transfer-Encoding", req.FormValue("te"))
+		rw.Header().Set("Transfer-Encoding", req.FormValue("te"))
 		switch {
 		case req.FormValue("overwrite") == "1":
 			_, err := rw.Write([]byte("foo TOO LONG"))
@@ -303,7 +303,7 @@ func TestIdentityResponse(t *testing.T) {
 				t.Errorf("expected ErrContentLength; got %v", err)
 			}
 		case req.FormValue("underwrite") == "1":
-			rw.SetHeader("Content-Length", "500")
+			rw.Header().Set("Content-Length", "500")
 			rw.Write([]byte("too short"))
 		default:
 			rw.Write([]byte("foo"))

src/pkg/http/server.go

@@ -54,17 +54,10 @@ type ResponseWriter interface {
 	// UsingTLS returns true if the client is connected using TLS
 	UsingTLS() bool
 
-	// SetHeader sets a header line in the eventual response.
+	// Header returns the header map that will be sent by WriteHeader.
-	// For example, SetHeader("Content-Type", "text/html; charset=utf-8")
+	// Changing the header after a call to WriteHeader (or Write) has
-	// will result in the header line
+	// no effect.
-	//
+	Header() Header
-	//	Content-Type: text/html; charset=utf-8
-	//
-	// being sent. UTF-8 encoded HTML is the default setting for
-	// Content-Type in this library, so users need not make that
-	// particular call. Calls to SetHeader after WriteHeader (or Write)
-	// are ignored. An empty value removes the header if previously set.
-	SetHeader(string, string)
 
 	// Write writes the data to the connection as part of an HTTP reply.
 	// If WriteHeader has not yet been called, Write calls WriteHeader(http.StatusOK)
@@ -110,7 +103,7 @@ type response struct {
 	chunking      bool     // using chunked transfer encoding for reply body
 	wroteHeader   bool     // reply header has been written
 	wroteContinue bool     // 100 Continue response was written
-	header        map[string]string // reply header parameters
+	header        Header   // reply header parameters
 	written       int64    // number of bytes written in body
 	contentLength int64    // explicitly-declared Content-Length; or -1
 	status        int      // status code passed to WriteHeader
@@ -174,7 +167,7 @@ func (c *conn) readRequest() (w *response, err os.Error) {
 	w = new(response)
 	w.conn = c
 	w.req = req
-	w.header = make(map[string]string)
+	w.header = make(Header)
 	w.contentLength = -1
 
 	// Expect 100 Continue support
@@ -185,21 +178,16 @@ func (c *conn) readRequest() (w *response, err os.Error) {
 	return w, nil
 }
 
-// UsingTLS implements the ResponseWriter.UsingTLS
 func (w *response) UsingTLS() bool {
 	return w.conn.usingTLS
 }
 
-// RemoteAddr implements the ResponseWriter.RemoteAddr method
 func (w *response) RemoteAddr() string { return w.conn.remoteAddr }
 
-// SetHeader implements the ResponseWriter.SetHeader method
+func (w *response) Header() Header {
-// An empty value removes the header from the map.
+	return w.header
-func (w *response) SetHeader(hdr, val string) {
-	w.header[CanonicalHeaderKey(hdr)] = val, val != ""
 }
 
-// WriteHeader implements the ResponseWriter.WriteHeader method
 func (w *response) WriteHeader(code int) {
 	if w.conn.hijacked {
 		log.Print("http: response.WriteHeader on hijacked connection")
@@ -214,46 +202,47 @@ func (w *response) WriteHeader(code int) {
 	if code == StatusNotModified {
 		// Must not have body.
 		for _, header := range []string{"Content-Type", "Content-Length", "Transfer-Encoding"} {
-			if w.header[header] != "" {
+			if w.header.Get(header) != "" {
 				// TODO: return an error if WriteHeader gets a return parameter
 				// or set a flag on w to make future Writes() write an error page?
 				// for now just log and drop the header.
 				log.Printf("http: StatusNotModified response with header %q defined", header)
-				w.header[header] = "", false
+				w.header.Del(header)
 			}
 		}
 	} else {
 		// Default output is HTML encoded in UTF-8.
-		if w.header["Content-Type"] == "" {
+		if w.header.Get("Content-Type") == "" {
-			w.SetHeader("Content-Type", "text/html; charset=utf-8")
+			w.header.Set("Content-Type", "text/html; charset=utf-8")
 		}
 	}
 
-	if w.header["Date"] == "" {
+	if w.header.Get("Date") == "" {
-		w.SetHeader("Date", time.UTC().Format(TimeFormat))
+		w.Header().Set("Date", time.UTC().Format(TimeFormat))
 	}
 
 	// Check for a explicit (and valid) Content-Length header.
 	var hasCL bool
 	var contentLength int64
-	if clenStr, ok := w.header["Content-Length"]; ok {
+	if clenStr := w.header.Get("Content-Length"); clenStr != "" {
 		var err os.Error
 		contentLength, err = strconv.Atoi64(clenStr)
 		if err == nil {
 			hasCL = true
 		} else {
 			log.Printf("http: invalid Content-Length of %q sent", clenStr)
-			w.SetHeader("Content-Length", "")
+			w.header.Set("Content-Length", "")
 		}
 	}
 
-	te, hasTE := w.header["Transfer-Encoding"]
+	te := w.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.
 		log.Printf("http: WriteHeader called with both Transfer-Encoding of %q and a Content-Length of %d",
 			te, contentLength)
-		w.SetHeader("Content-Length", "")
+		w.header.Set("Content-Length", "")
 		hasCL = false
 	}
 
@@ -262,7 +251,7 @@ func (w *response) WriteHeader(code int) {
 	} else if hasCL {
 		w.chunking = false
 		w.contentLength = contentLength
-		w.SetHeader("Transfer-Encoding", "")
+		w.header.Del("Transfer-Encoding")
 	} else if w.req.ProtoAtLeast(1, 1) {
 		// HTTP/1.1 or greater: use chunked transfer encoding
 		// to avoid closing the connection at EOF.
@@ -270,20 +259,20 @@ func (w *response) WriteHeader(code int) {
 		// might have set.  Deal with that as need arises once we have a valid
 		// use case.
 		w.chunking = true
-		w.SetHeader("Transfer-Encoding", "chunked")
+		w.header.Set("Transfer-Encoding", "chunked")
 	} else {
 		// HTTP version < 1.1: cannot do chunked transfer
 		// encoding and we don't know the Content-Length so
 		// signal EOF by closing connection.
 		w.closeAfterReply = true
 		w.chunking = false                // redundant
-		w.SetHeader("Transfer-Encoding", "") // in case already set
+		w.header.Del("Transfer-Encoding") // in case already set
 	}
 
 	if w.req.wantsHttp10KeepAlive() && (w.req.Method == "HEAD" || hasCL) {
 		_, connectionHeaderSet := w.header["Connection"]
 		if !connectionHeaderSet {
-			w.SetHeader("Connection", "keep-alive")
+			w.header.Set("Connection", "keep-alive")
 		}
 	} else if !w.req.ProtoAtLeast(1, 1) {
 		// Client did not ask to keep connection alive.
@@ -292,7 +281,7 @@ func (w *response) WriteHeader(code int) {
 
 	// Cannot use Content-Length with non-identity Transfer-Encoding.
 	if w.chunking {
-		w.SetHeader("Content-Length", "")
+		w.header.Set("Content-Length", "")
 	}
 	if !w.req.ProtoAtLeast(1, 0) {
 		return
@@ -307,13 +296,10 @@ func (w *response) WriteHeader(code int) {
 		text = "status code " + codestring
 	}
 	io.WriteString(w.conn.buf, proto+" "+codestring+" "+text+"\r\n")
-	for k, v := range w.header {
+	writeSortedHeader(w.conn.buf, w.header, nil)
-		io.WriteString(w.conn.buf, k+": "+v+"\r\n")
-	}
 	io.WriteString(w.conn.buf, "\r\n")
 }
 
-// Write implements the ResponseWriter.Write method
 func (w *response) Write(data []byte) (n int, err os.Error) {
 	if w.conn.hijacked {
 		log.Print("http: response.Write on hijacked connection")
@@ -388,7 +374,7 @@ func errorKludge(w *response) {
 	msg += " would ignore this error page if this text weren't here.\n"
 
 	// Is it text?  ("Content-Type" is always in the map)
-	baseType := strings.Split(w.header["Content-Type"], ";", 2)[0]
+	baseType := strings.Split(w.header.Get("Content-Type"), ";", 2)[0]
 	switch baseType {
 	case "text/html":
 		io.WriteString(w, "<!-- ")
@@ -408,8 +394,8 @@ func (w *response) finishRequest() {
 	// If this was an HTTP/1.0 request with keep-alive and we sent a Content-Length
 	// back, we can make this a keep-alive response ...
 	if w.req.wantsHttp10KeepAlive() {
-		_, sentLength := w.header["Content-Length"]
+		sentLength := w.header.Get("Content-Length") != ""
-		if sentLength && w.header["Connection"] == "keep-alive" {
+		if sentLength && w.header.Get("Connection") == "keep-alive" {
 			w.closeAfterReply = false
 		}
 	}
@@ -431,7 +417,6 @@ func (w *response) finishRequest() {
 	}
 }
 
-// Flush implements the ResponseWriter.Flush method.
 func (w *response) Flush() {
 	if !w.wroteHeader {
 		w.WriteHeader(StatusOK)
@@ -504,7 +489,7 @@ func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) {
 
 // Error replies to the request with the specified error message and HTTP code.
 func Error(w ResponseWriter, error string, code int) {
-	w.SetHeader("Content-Type", "text/plain; charset=utf-8")
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 	w.WriteHeader(code)
 	fmt.Fprintln(w, error)
 }
@@ -557,7 +542,7 @@ func Redirect(w ResponseWriter, r *Request, url string, code int) {
 		}
 	}
 
-	w.SetHeader("Location", url)
+	w.Header().Set("Location", url)
 	w.WriteHeader(code)
 
 	// RFC2616 recommends that a short note "SHOULD" be included in the
@@ -680,7 +665,7 @@ func (mux *ServeMux) match(path string) Handler {
 func (mux *ServeMux) ServeHTTP(w ResponseWriter, r *Request) {
 	// Clean path to canonical form and redirect.
 	if p := cleanPath(r.URL.Path); p != r.URL.Path {
-		w.SetHeader("Location", p)
+		w.Header().Set("Location", p)
 		w.WriteHeader(StatusMovedPermanently)
 		return
 	}
@@ -833,7 +818,7 @@ func ListenAndServe(addr string, handler Handler) os.Error {
 //	)
 //
 //	func handler(w http.ResponseWriter, req *http.Request) {
-//		w.SetHeader("Content-Type", "text/plain")
+//		w.Header().Set("Content-Type", "text/plain")
 //		w.Write([]byte("This is an example server.\n"))
 //	}
 //

src/pkg/http/triv.go

@@ -56,7 +56,7 @@ func (ctr *Counter) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 var booleanflag = flag.Bool("boolean", true, "another flag for testing")
 
 func FlagServer(w http.ResponseWriter, req *http.Request) {
-	w.SetHeader("content-type", "text/plain; charset=utf-8")
+	w.Header.Set("Content-Type", "text/plain; charset=utf-8")
 	fmt.Fprint(w, "Flags:\n")
 	flag.VisitAll(func(f *flag.Flag) {
 		if f.Value.String() != f.DefValue {
@@ -93,7 +93,7 @@ func (ch Chan) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 
 // exec a program, redirecting output
 func DateServer(rw http.ResponseWriter, req *http.Request) {
-	rw.SetHeader("content-type", "text/plain; charset=utf-8")
+	rw.Header().Set("Content-Type", "text/plain; charset=utf-8")
 	r, w, err := os.Pipe()
 	if err != nil {
 		fmt.Fprintf(rw, "pipe: %s\n", err)

src/pkg/rpc/server.go

@@ -509,7 +509,7 @@ var connected = "200 Connected to Go RPC"
 // ServeHTTP implements an http.Handler that answers RPC requests.
 func (server *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	if req.Method != "CONNECT" {
-		w.SetHeader("Content-Type", "text/plain; charset=utf-8")
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 		w.WriteHeader(http.StatusMethodNotAllowed)
 		io.WriteString(w, "405 must CONNECT\n")
 		return