C#•5d ago

Solution for lots of flags

Hi. When I need to have rights management in my programs, I usually make an enum "Rights" as [Flags] type long and do like Invalid = -1, None = 0, AddGame = 1, DelGame = 2, LaunchGame = 4, EditGame = 8 ..etc I like because it's simple bitwise and I made an extension method so I can just do like function DeleteGame(Game game) { if (!ActiveUser?.Rights.HasPermission(Rights.DeleteGame) ?? false) return; However... I'm doing a big complex app and it's gonna have more rights than I have bits in a long. What is a good way to handle it at that point? I figured I could do enums like Rights_Context1 Rights_Context2 ..etc then I was trying to figure out how to store them in the user. I figured maybe public List<Enum> Rights then load them all into there, but then how do I check them? Loop and check what type each entry is then compare? That seems awkward. Is there any easy solution for having large amounts of flags in an enum? I assume I need a bitwise enum because I want to store the data in the db, and a bigint seemed the easiest way. I suppose I could do a permissions related table then make single entries per flag but that seems very inefficient.

7 Replies

Jimmacle•5d ago

if you have a large amount of flags you shouldn't use an enum, because you're fundamentally limited by the largest integer type you can use as the enum type i would use a permissions table, databases are designed for that type of layout it might seem more inefficient but it's also less likely to break by accident and it would only be a problem if you actually run into performance issues because of it

Lupusregina BetaOP•5d ago

So like when I do a permission check, just have a method that does like SELECT index FROM permissions WHERE uid = ?uid AND permcode = ?perm Then pass the user Guid and maybe a string like "game.delete" then if a row is returned, I know they're authorized else deny? Roundtripping to MySQL that much won't be an issue? Well, it's not like I'm making some high use app anyway lol so I doubt it'd be an issue. Just curious. Hmm I could keep a cache in the perm manager and when an admin changes ppls perms, flush cache and/or flush it every X minutes that may reduce load.

Jimmacle•5d ago

do you necessarily need to or can you cache permissions for some amount of time? you can just load them into a hashset and refresh it if the permissions are changed

Lupusregina BetaOP•5d ago

Thanks, appreciate the advice! I have a followup question. I'm working on implementing this. I have a static Perm class now, with a private Dictionary<Guid, HashSet<string>> Permissions. I have an Init method that populates the dict with the user's ID's then all the nodes to which they have permission. Then I have:

public static bool Has(string node, Guid id = default(Guid)) {
  if (string.IsNullOrEmpty(node)) return false;
  if (id == Guid.Empty) {
    if (cfg.LoggedInUser == Guid.Empty) return false;
    id = cfg.LoggedInUser;
  }
  if (!Permissions.ContainsKey(id)) return false;

  return Permissions[id].Contains("administrator") || Permissions[id].Contains(node).ToLower().Trim();
}

public static bool Has(string node, Guid id = default(Guid)) {
  if (string.IsNullOrEmpty(node)) return false;
  if (id == Guid.Empty) {
    if (cfg.LoggedInUser == Guid.Empty) return false;
    id = cfg.LoggedInUser;
  }
  if (!Permissions.ContainsKey(id)) return false;

  return Permissions[id].Contains("administrator") || Permissions[id].Contains(node).ToLower().Trim();
}

But I'd like to support inheritance. Like If I have nodes like:

Game.View
Game.Edit
Game.Delete
Game.Launch

Game.View
Game.Edit
Game.Delete
Game.Launch

If I'm checking for Game.View, then if they have edit, delete or launch it stands to reason that view is a given. What would be a good way to handle that?

public static class Perm {
  private static Dictionary<Guid, HashSet<string>> Permissions = new Dictionary<Guid, HashSet<string>>();
  private static Dictionary<string, HashSet<string>> Inheritance = new Dictionary<string, HashSet<string>>();

  public static void Init() {
    foreach (User user in DataManager.GetUsers()) {
      Permissions[user.Id] = DataManager.GetUserPermissionSet(user.Id);
    }
    Inheritance = DataManager.GetInheritanceSet();
  }

  public static bool Has(string node, Guid id = default(Guid)) {
    if (string.IsNullOrEmpty(node)) return false;
    node = node.ToLower().Trim();

    if (id == Guid.Empty) {
      if (cfg.LoggedInUser == Guid.Empty) return false;
      id = cfg.LoggedInUser;
    }

    if (!Permissions.ContainsKey(id)) return false;
    if (Permissions[id].Contains("administrator") || Permissions[id].Contains(node)) return true;
    if (!Inheritance.ContainsKey(node)) return false;

    return Inheritance[node].Any(x => Permissions[id].Contains(x));
  }
}

public static class Perm {
  private static Dictionary<Guid, HashSet<string>> Permissions = new Dictionary<Guid, HashSet<string>>();
  private static Dictionary<string, HashSet<string>> Inheritance = new Dictionary<string, HashSet<string>>();

  public static void Init() {
    foreach (User user in DataManager.GetUsers()) {
      Permissions[user.Id] = DataManager.GetUserPermissionSet(user.Id);
    }
    Inheritance = DataManager.GetInheritanceSet();
  }

  public static bool Has(string node, Guid id = default(Guid)) {
    if (string.IsNullOrEmpty(node)) return false;
    node = node.ToLower().Trim();

    if (id == Guid.Empty) {
      if (cfg.LoggedInUser == Guid.Empty) return false;
      id = cfg.LoggedInUser;
    }

    if (!Permissions.ContainsKey(id)) return false;
    if (Permissions[id].Contains("administrator") || Permissions[id].Contains(node)) return true;
    if (!Inheritance.ContainsKey(node)) return false;

    return Inheritance[node].Any(x => Permissions[id].Contains(x));
  }
}

GetInheritanceSet returns a HashSet with all the nodes that would grant the key node, like

Dictionary<string, HashSet<string>> {
  { "game.view", new HashSet<string>() {
      "game.edit",
      "game.delete",
      "game.launch"
    }
  },
  { "game.edit", new HashSet<string>() {
      "game.delete"
    }
  }
};

Dictionary<string, HashSet<string>> {
  { "game.view", new HashSet<string>() {
      "game.edit",
      "game.delete",
      "game.launch"
    }
  },
  { "game.edit", new HashSet<string>() {
      "game.delete"
    }
  }
};

So if I do Has("Game.View") and the user doesn't explicitly have that but they do have Game.Launch, it would return true. Does that look workable?

Anton•5d ago

yes there's no reason for it to be a hash set if it's static data though also, what is that ToLower().Trim() doing there? I liked the bitsets. I'd prefer integer ids instead of strings at least if you know the max amount of roles you'll have, you can do a struct with a bunch of integer fields to accommodate the max for the bitset

Lupusregina BetaOP•5d ago

Ahh. What would I use if not the hashset for the static data then? The tolower trim was to normalize the input, but that's gone now as I switched to using an enum for the permission nodes rather than typing them as strings. Roles are variable, users can add them. Thanks!

Anton•5d ago

an array

Gaming

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Solution for lots of flags

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