blob: 0c64f16a3905e6a57c13bb3a64ec669179c1e2d8 [file] [log] [blame]
// Copyright 2015 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package cors handles cross-origin HTTP requests (CORS).
package cors
import (
"fmt"
"net/http"
"net/url"
"sort"
"strings"
)
type CORSInfo map[string]bool
// Set implements the flag.Value interface to allow users to define a list of CORS origins
func (ci *CORSInfo) Set(s string) error {
m := make(map[string]bool)
for _, v := range strings.Split(s, ",") {
v = strings.TrimSpace(v)
if v == "" {
continue
}
if v != "*" {
if _, err := url.Parse(v); err != nil {
return fmt.Errorf("Invalid CORS origin: %s", err)
}
}
m[v] = true
}
*ci = CORSInfo(m)
return nil
}
func (ci *CORSInfo) String() string {
o := make([]string, 0)
for k := range *ci {
o = append(o, k)
}
sort.StringSlice(o).Sort()
return strings.Join(o, ",")
}
// OriginAllowed determines whether the server will allow a given CORS origin.
func (c CORSInfo) OriginAllowed(origin string) bool {
return c["*"] || c[origin]
}
type CORSHandler struct {
Handler http.Handler
Info *CORSInfo
}
// addHeader adds the correct cors headers given an origin
func (h *CORSHandler) addHeader(w http.ResponseWriter, origin string) {
w.Header().Add("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
w.Header().Add("Access-Control-Allow-Origin", origin)
w.Header().Add("Access-Control-Allow-Headers", "accept, content-type, authorization")
}
// ServeHTTP adds the correct CORS headers based on the origin and returns immediately
// with a 200 OK if the method is OPTIONS.
func (h *CORSHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
// Write CORS header.
if h.Info.OriginAllowed("*") {
h.addHeader(w, "*")
} else if origin := req.Header.Get("Origin"); h.Info.OriginAllowed(origin) {
h.addHeader(w, origin)
}
if req.Method == "OPTIONS" {
w.WriteHeader(http.StatusOK)
return
}
h.Handler.ServeHTTP(w, req)
}