etcd/server/cors_handler.go
Brandon Philips a1ec895b91 feat(server): introduce a cors handler
Introduce a handler that lives under the gorilla mux and adds the
correct headers based on the request and always returns 200 OK when
there OPTIONS is called on a URL.

This fixes the ability to DELETE from the dashboard on peer X when peer
Y is the leader. As a side effect it reveals some bugs in the dashboard
though notably:

- Due to the RTT immediatly refreshing the dashboard doesn't work and
  deleted keys are still there

- For some reason PUTS from peer X are creating directories and not
  keys.
2013-11-21 09:25:21 -08:00

79 lines
2.0 KiB
Go

/*
Copyright 2013 CoreOS Inc.
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 server
import (
"fmt"
"net/http"
"net/url"
"github.com/gorilla/mux"
)
type corsHandler struct {
router *mux.Router
corsOrigins map[string]bool
}
// AllowOrigins sets a comma-delimited list of origins that are allowed.
func (s *corsHandler) AllowOrigins(origins []string) error {
// Construct a lookup of all origins.
m := make(map[string]bool)
for _, v := range origins {
if v != "*" {
if _, err := url.Parse(v); err != nil {
return fmt.Errorf("Invalid CORS origin: %s", err)
}
}
m[v] = true
}
s.corsOrigins = m
return nil
}
// OriginAllowed determines whether the server will allow a given CORS origin.
func (c *corsHandler) OriginAllowed(origin string) bool {
return c.corsOrigins["*"] || c.corsOrigins[origin]
}
// 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)
}
// ServeHTTP adds the correct CORS headers based on the origin and returns immediatly
// with a 200 OK if the method is OPTIONS.
func (h *corsHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
// Write CORS header.
if h.OriginAllowed("*") {
h.addHeader(w, "*")
} else if origin := req.Header.Get("Origin"); h.OriginAllowed(origin) {
h.addHeader(w, origin)
}
if req.Method == "OPTIONS" {
w.WriteHeader(http.StatusOK)
return
}
h.router.ServeHTTP(w, req)
}