http: permit empty Reason-Phrase in response Status-Line

Fixes #1388.

R=rsc
CC=golang-dev
https://golang.org/cl/3749043

src/pkg/http/response.go

@@ -86,10 +86,14 @@ func ReadResponse(r *bufio.Reader, requestMethod string) (resp *Response, err os
 		return nil, err
 	}
 	f := strings.Split(line, " ", 3)
-	if len(f) < 3 {
+	if len(f) < 2 {
 		return nil, &badStringError{"malformed HTTP response", line}
 	}
-	resp.Status = f[1] + " " + f[2]
+	reasonPhrase := ""
+	if len(f) > 2 {
+		reasonPhrase = f[2]
+	}
+	resp.Status = f[1] + " " + reasonPhrase
 	resp.StatusCode, err = strconv.Atoi(f[1])
 	if err != nil {
 		return nil, &badStringError{"malformed HTTP status code", f[1]}

src/pkg/http/response_test.go

@@ -122,6 +122,44 @@ var respTests = []respTest{
 
 		"Body here\n",
 	},
+
+	// Status line without a Reason-Phrase, but trailing space.
+	// (permitted by RFC 2616)
+	{
+		"HTTP/1.0 303 \r\n\r\n",
+		Response{
+			Status:        "303 ",
+			StatusCode:    303,
+			Proto:         "HTTP/1.0",
+			ProtoMajor:    1,
+			ProtoMinor:    0,
+			RequestMethod: "GET",
+			Header:        map[string]string{},
+			Close:         true,
+			ContentLength: -1,
+		},
+
+		"",
+	},
+
+	// Status line without a Reason-Phrase, and no trailing space.
+	// (not permitted by RFC 2616, but we'll accept it anyway)
+	{
+		"HTTP/1.0 303\r\n\r\n",
+		Response{
+			Status:        "303 ",
+			StatusCode:    303,
+			Proto:         "HTTP/1.0",
+			ProtoMajor:    1,
+			ProtoMinor:    0,
+			RequestMethod: "GET",
+			Header:        map[string]string{},
+			Close:         true,
+			ContentLength: -1,
+		},
+
+		"",
+	},
 }
 
 func TestReadResponse(t *testing.T) {