| // 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) |
| } |