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/* | |
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" | |
"k8s.io/klog" | |
) | |
// 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 { | |
klog.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 | |
} |