refactor: move helper functions under common, in usage specific named files (#1540)

Signed-off-by: Alex Stan <alexandrustan96@yahoo.ro>

pkg/common/http_server.go

@@ -0,0 +1,68 @@
+package common
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/gorilla/mux"
+	jsoniter "github.com/json-iterator/go"
+
+	"zotregistry.io/zot/pkg/api/constants"
+	apiErr "zotregistry.io/zot/pkg/api/errors"
+)
+
+func AllowedMethods(methods ...string) []string {
+	return append(methods, http.MethodOptions)
+}
+
+func AddExtensionSecurityHeaders() mux.MiddlewareFunc { //nolint:varnamelen
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
+			resp.Header().Set("X-Content-Type-Options", "nosniff")
+
+			next.ServeHTTP(resp, req)
+		})
+	}
+}
+
+func ACHeadersHandler(allowedMethods ...string) mux.MiddlewareFunc {
+	headerValue := strings.Join(allowedMethods, ",")
+
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(resp http.ResponseWriter, req *http.Request) {
+			resp.Header().Set("Access-Control-Allow-Methods", headerValue)
+			resp.Header().Set("Access-Control-Allow-Headers", "Authorization,content-type")
+
+			if req.Method == http.MethodOptions {
+				return
+			}
+
+			next.ServeHTTP(resp, req)
+		})
+	}
+}
+
+func AuthzFail(w http.ResponseWriter, realm string, delay int) {
+	time.Sleep(time.Duration(delay) * time.Second)
+	w.Header().Set("WWW-Authenticate", realm)
+	w.Header().Set("Content-Type", "application/json")
+	WriteJSON(w, http.StatusForbidden, apiErr.NewErrorList(apiErr.NewError(apiErr.DENIED)))
+}
+
+func WriteJSON(response http.ResponseWriter, status int, data interface{}) {
+	json := jsoniter.ConfigCompatibleWithStandardLibrary
+
+	body, err := json.Marshal(data)
+	if err != nil {
+		panic(err)
+	}
+
+	WriteData(response, status, constants.DefaultMediaType, body)
+}
+
+func WriteData(w http.ResponseWriter, status int, mediaType string, data []byte) {
+	w.Header().Set("Content-Type", mediaType)
+	w.WriteHeader(status)
+	_, _ = w.Write(data)
+}