Fix beacon api handler (#8999)

cl/beacon/handler/format.go

@@ -57,7 +57,7 @@ func (r *beaconResponse) withFinalized(finalized bool) (out *beaconResponse) {
 	out.Finalized = new(bool)
 	out.ExecutionOptimistic = new(bool)
 	out.Finalized = &finalized
-	return r
+	return out
 }
 
 func (r *beaconResponse) withVersion(version clparams.StateVersion) (out *beaconResponse) {
@@ -65,7 +65,7 @@ func (r *beaconResponse) withVersion(version clparams.StateVersion) (out *beacon
 	*out = *r
 	out.Version = new(clparams.StateVersion)
 	out.Version = &version
-	return r
+	return out
 }
 
 //// In case of it being a json we need to also expose finalization, version, etc...

cl/beacon/handler/handler.go

@@ -18,7 +18,7 @@ import (
 
 type ApiHandler struct {
 	o   sync.Once
-	mux chi.Router
+	mux *chi.Mux
 
 	blockReader     freezeblocks.BeaconSnapshotReader
 	indiciesDB      kv.RoDB

cl/beacon/handler/states.go

@@ -148,7 +148,8 @@ func (a *ApiHandler) getStateRoot(r *http.Request) (*beaconResponse, error) {
 		return nil, err
 	}
 
-	return newBeaconResponse(&rootResponse{Root: stateRoot}).withFinalized(canonicalRoot == root && *slot <= a.forkchoiceStore.FinalizedSlot()), nil
+	return newBeaconResponse(&rootResponse{Root: stateRoot}).
+		withFinalized(canonicalRoot == root && *slot <= a.forkchoiceStore.FinalizedSlot()), nil
 }
 
 func (a *ApiHandler) getFullState(r *http.Request) (*beaconResponse, error) {

cl/beacon/router.go

@@ -1,6 +1,7 @@
 package beacon
 
 import (
+	"context"
 	"net"
 	"net/http"
 	"strings"
@@ -39,7 +40,8 @@ func ListenAndServe(beaconHandler *LayeredBeaconHandler, routerCfg beacon_router
 	mux.HandleFunc("/eth/*", func(w http.ResponseWriter, r *http.Request) {
 		nfw := &notFoundNoWriter{rw: w}
 		beaconHandler.ValidatorApi.ServeHTTP(nfw, r)
-		if nfw.code == 404 || nfw.code == 0 {
+		r = r.WithContext(context.WithValue(r.Context(), chi.RouteCtxKey, chi.NewRouteContext()))
+		if isNotFound(nfw.code) || nfw.code == 0 {
 			beaconHandler.ArchiveApi.ServeHTTP(w, r)
 		}
 	})
@@ -65,14 +67,3 @@ func ListenAndServe(beaconHandler *LayeredBeaconHandler, routerCfg beacon_router
 	}
 	return nil
 }
-
-func newBeaconMiddleware(next http.Handler) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		contentType := r.Header.Get("Content-Type")
-		if contentType != "application/json" && contentType != "" {
-			http.Error(w, "Content-Type header must be application/json", http.StatusUnsupportedMediaType)
-			return
-		}
-		next.ServeHTTP(w, r)
-	})
-}

cl/beacon/rw.go

@@ -11,11 +11,18 @@ type notFoundNoWriter struct {
 	headers http.Header
 }
 
+func isNotFound(code int) bool {
+	return code == 404 || code == 405
+}
+
 func (f *notFoundNoWriter) Header() http.Header {
-	if f.code == 404 {
+	if isNotFound(f.code) {
 		return make(http.Header)
 	}
-	return f.rw.Header()
+	if f.headers == nil {
+		f.headers = make(http.Header)
+	}
+	return f.headers
 }
 
 func (f *notFoundNoWriter) Write(xs []byte) (int, error) {
@@ -23,7 +30,7 @@ func (f *notFoundNoWriter) Write(xs []byte) (int, error) {
 	if f.code == 0 {
 		f.WriteHeader(200)
 	}
-	if f.code == 404 {
+	if isNotFound(f.code) {
 		return 0, nil
 	}
 	// pass on the write
@@ -34,9 +41,19 @@ func (f *notFoundNoWriter) WriteHeader(statusCode int) {
 	if f.code != 0 {
 		return
 	}
-	if f.code != 404 {
-		f.rw.WriteHeader(statusCode)
-	}
-	// if it's a 404 and we are not at our last handler, set the target to an io.Discard
 	f.code = statusCode
+	if isNotFound(statusCode) {
+		f.headers = nil
+		return
+	}
+	f.rw.WriteHeader(statusCode)
+	// if we get here, it means it is a successful write.
+	if f.headers != nil {
+		for k, v := range f.headers {
+			for _, x := range v {
+				f.rw.Header().Add(k, x)
+			}
+		}
+	}
+	f.headers = f.rw.Header()
 }

cl/beacon/validatorapi/handler.go

@@ -17,18 +17,18 @@ type ValidatorApiHandler struct {
 	GenesisCfg     *clparams.GenesisConfig
 
 	o   sync.Once
-	mux chi.Router
+	mux *chi.Mux
 }
 
 func (v *ValidatorApiHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	v.o.Do(func() {
 		v.mux = chi.NewRouter()
-		v.init(v.mux)
+		v.Route(v.mux)
 	})
 	v.mux.ServeHTTP(w, r)
 }
 
-func (v *ValidatorApiHandler) init(r chi.Router) {
+func (v *ValidatorApiHandler) Route(r chi.Router) {
 	r.Route("/eth", func(r chi.Router) {
 		r.Route("/v1", func(r chi.Router) {
 			r.Route("/beacon", func(r chi.Router) {