feat: header based acls (#337)

* feat: add header decoder

* feat: allow for dash substitute over slash for environments like kubernetes

* feat: use decoded headers in proxy controller

* refactor: simplify decode header to node function

* refactor: use stdlib prefix check in header decoder

* fix: lowercase key and filter before comparing

internal/utils/security_utils.go

@@ -46,6 +46,8 @@ func GetBasicAuth(username string, password string) string {
 }
 
 func FilterIP(filter string, ip string) (bool, error) {
+	filter = strings.Replace(filter, "-", "/", -1)
+
 	ipAddr := net.ParseIP(ip)
 
 	if strings.Contains(filter, "/") {