77 lines
2.0 KiB
Go
77 lines
2.0 KiB
Go
/*
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Copyright 2013 CoreOS Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package server
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import (
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"fmt"
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"net/http"
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"net/url"
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"github.com/gorilla/mux"
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)
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type corsHandler struct {
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router *mux.Router
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corsOrigins map[string]bool
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}
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// AllowOrigins sets a comma-delimited list of origins that are allowed.
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func (s *corsHandler) AllowOrigins(origins []string) error {
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// Construct a lookup of all origins.
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m := make(map[string]bool)
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for _, v := range origins {
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if v != "*" {
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if _, err := url.Parse(v); err != nil {
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return fmt.Errorf("Invalid CORS origin: %s", err)
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}
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}
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m[v] = true
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}
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s.corsOrigins = m
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return nil
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}
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// OriginAllowed determines whether the server will allow a given CORS origin.
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func (c *corsHandler) OriginAllowed(origin string) bool {
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return c.corsOrigins["*"] || c.corsOrigins[origin]
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}
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// addHeader adds the correct cors headers given an origin
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func (h *corsHandler) addHeader(w http.ResponseWriter, origin string) {
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w.Header().Add("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
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w.Header().Add("Access-Control-Allow-Origin", origin)
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}
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// ServeHTTP adds the correct CORS headers based on the origin and returns immediatly
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// with a 200 OK if the method is OPTIONS.
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func (h *corsHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
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// Write CORS header.
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if h.OriginAllowed("*") {
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h.addHeader(w, "*")
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} else if origin := req.Header.Get("Origin"); h.OriginAllowed(origin) {
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h.addHeader(w, origin)
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}
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if req.Method == "OPTIONS" {
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w.WriteHeader(http.StatusOK)
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return
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}
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h.router.ServeHTTP(w, req)
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}
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