| /* |
| Copyright 2016 The Kubernetes 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 filters |
| |
| import ( |
| "net/http" |
| "regexp" |
| "strings" |
| |
| "github.com/golang/glog" |
| ) |
| |
| // TODO: use restful.CrossOriginResourceSharing |
| // See github.com/emicklei/go-restful/blob/master/examples/restful-CORS-filter.go, and |
| // github.com/emicklei/go-restful/blob/master/examples/restful-basic-authentication.go |
| // Or, for a more detailed implementation use https://github.com/martini-contrib/cors |
| // or implement CORS at your proxy layer. |
| |
| // WithCORS is a simple CORS implementation that wraps an http Handler. |
| // Pass nil for allowedMethods and allowedHeaders to use the defaults. If allowedOriginPatterns |
| // is empty or nil, no CORS support is installed. |
| func WithCORS(handler http.Handler, allowedOriginPatterns []string, allowedMethods []string, allowedHeaders []string, exposedHeaders []string, allowCredentials string) http.Handler { |
| if len(allowedOriginPatterns) == 0 { |
| return handler |
| } |
| allowedOriginPatternsREs := allowedOriginRegexps(allowedOriginPatterns) |
| return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) { |
| origin := req.Header.Get("Origin") |
| if origin != "" { |
| allowed := false |
| for _, re := range allowedOriginPatternsREs { |
| if allowed = re.MatchString(origin); allowed { |
| break |
| } |
| } |
| if allowed { |
| w.Header().Set("Access-Control-Allow-Origin", origin) |
| // Set defaults for methods and headers if nothing was passed |
| if allowedMethods == nil { |
| allowedMethods = []string{"POST", "GET", "OPTIONS", "PUT", "DELETE", "PATCH"} |
| } |
| if allowedHeaders == nil { |
| allowedHeaders = []string{"Content-Type", "Content-Length", "Accept-Encoding", "X-CSRF-Token", "Authorization", "X-Requested-With", "If-Modified-Since"} |
| } |
| if exposedHeaders == nil { |
| exposedHeaders = []string{"Date"} |
| } |
| w.Header().Set("Access-Control-Allow-Methods", strings.Join(allowedMethods, ", ")) |
| w.Header().Set("Access-Control-Allow-Headers", strings.Join(allowedHeaders, ", ")) |
| w.Header().Set("Access-Control-Expose-Headers", strings.Join(exposedHeaders, ", ")) |
| w.Header().Set("Access-Control-Allow-Credentials", allowCredentials) |
| |
| // Stop here if its a preflight OPTIONS request |
| if req.Method == "OPTIONS" { |
| w.WriteHeader(http.StatusNoContent) |
| return |
| } |
| } |
| } |
| // Dispatch to the next handler |
| handler.ServeHTTP(w, req) |
| }) |
| } |
| |
| func allowedOriginRegexps(allowedOrigins []string) []*regexp.Regexp { |
| res, err := compileRegexps(allowedOrigins) |
| if err != nil { |
| glog.Fatalf("Invalid CORS allowed origin, --cors-allowed-origins flag was set to %v - %v", strings.Join(allowedOrigins, ","), err) |
| } |
| return res |
| } |
| |
| // Takes a list of strings and compiles them into a list of regular expressions |
| func compileRegexps(regexpStrings []string) ([]*regexp.Regexp, error) { |
| regexps := []*regexp.Regexp{} |
| for _, regexpStr := range regexpStrings { |
| r, err := regexp.Compile(regexpStr) |
| if err != nil { |
| return []*regexp.Regexp{}, err |
| } |
| regexps = append(regexps, r) |
| } |
| return regexps, nil |
| } |