80 lines
2.6 KiB
Go
80 lines
2.6 KiB
Go
package mux
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import (
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"net/http"
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"strings"
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)
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// MiddlewareFunc is a function which receives an http.Handler and returns another http.Handler.
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// Typically, the returned handler is a closure which does something with the http.ResponseWriter and http.Request passed
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// to it, and then calls the handler passed as parameter to the MiddlewareFunc.
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type MiddlewareFunc func(http.Handler) http.Handler
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// middleware interface is anything which implements a MiddlewareFunc named Middleware.
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type middleware interface {
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Middleware(handler http.Handler) http.Handler
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}
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// Middleware allows MiddlewareFunc to implement the middleware interface.
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func (mw MiddlewareFunc) Middleware(handler http.Handler) http.Handler {
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return mw(handler)
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}
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// Use appends a MiddlewareFunc to the chain. Middleware can be used to intercept or otherwise modify requests and/or responses, and are executed in the order that they are applied to the Router.
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func (r *Router) Use(mwf ...MiddlewareFunc) {
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for _, fn := range mwf {
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r.middlewares = append(r.middlewares, fn)
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}
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}
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// useInterface appends a middleware to the chain. Middleware can be used to intercept or otherwise modify requests and/or responses, and are executed in the order that they are applied to the Router.
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func (r *Router) useInterface(mw middleware) {
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r.middlewares = append(r.middlewares, mw)
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}
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// CORSMethodMiddleware automatically sets the Access-Control-Allow-Methods response header
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// on requests for routes that have an OPTIONS method matcher to all the method matchers on
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// the route. Routes that do not explicitly handle OPTIONS requests will not be processed
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// by the middleware. See examples for usage.
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func CORSMethodMiddleware(r *Router) MiddlewareFunc {
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
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allMethods, err := getAllMethodsForRoute(r, req)
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if err == nil {
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for _, v := range allMethods {
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if v == http.MethodOptions {
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w.Header().Set("Access-Control-Allow-Methods", strings.Join(allMethods, ","))
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}
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}
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}
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next.ServeHTTP(w, req)
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})
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}
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}
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// getAllMethodsForRoute returns all the methods from method matchers matching a given
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// request.
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func getAllMethodsForRoute(r *Router, req *http.Request) ([]string, error) {
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var allMethods []string
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err := r.Walk(func(route *Route, _ *Router, _ []*Route) error {
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for _, m := range route.matchers {
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if _, ok := m.(*routeRegexp); ok {
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if m.Match(req, &RouteMatch{}) {
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methods, err := route.GetMethods()
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if err != nil {
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return err
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}
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allMethods = append(allMethods, methods...)
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}
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break
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}
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}
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return nil
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})
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return allMethods, err
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}
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