Steam OpenID auth linking (#5650)

## Short description
<!-- What do you propose to change with your PR? -->

Allows players to link and use steam as login option.

## Why we need to add this
<!-- What is the reason for adding these changes? Please post links to
Discussions as well as Bug Reports here. Please describe how this will
change the game balance. -->

Some of our users doesn't like discord OAuth, so we're providing better
way.

## Checks
<!-- check boxes for faster reviewing of your PR -->

- [x] I do not require assistance to complete the PR.
- [x] Before posting/requesting review of a PR, I have verified that the
changes work.
- [x] I have added screenshots/videos of the changes, or this PR does
not change in-game mechanics.
- [x] I affirm that my changes are licensed under the [MIT
License](https://github.com/ss14Starlight/space-station-14/blob/Starlight/LICENSE.TXT)
and grant permission for use in this repository under its conditions.

This PR won't get Changelog, just because it doesn't affect game at all,
it affects only Launcher and NullLink, users will get announcement when
this will work(currently it just links your steam with your SS14
account, that's all)

Author: Rinary1

Content.Client/Info/LinkBanner.cs

@@ -48,6 +48,14 @@ public LinkBanner()
                     uriOpener.OpenUri(link);
             };
             buttons.AddChild(button);
+
+            var steamButton = new Button { Text = Loc.GetString("server-info-connect-steam-button") };
+            steamButton.OnPressed += _ => {
+                var link = _playerRoles.GetSteamLink();
+                if (link != null)
+                    uriOpener.OpenUri(link);
+            };
+            buttons.AddChild(steamButton);
             // NullLink end
 
             var guidebookController = UserInterfaceManager.GetUIController<GuidebookUIController>();

Content.Client/Options/UI/EscapeMenu.xaml

@@ -7,6 +7,7 @@
 
     <BoxContainer Orientation="Vertical" SeparationOverride="4" MinWidth="150">
         <Button Access="Public" Name="DiscordButton" Text="{Loc 'ui-escape-connect-discord'}"/>
+		<Button Access="Public" Name="SteamButton" Text="{Loc 'ui-escape-connect-steam'}"/>
         <changelog:ChangelogButton Access="Public" Name="ChangelogButton"/>
         <ui:VoteCallMenuButton />
         <PanelContainer StyleClasses="LowDivider" Margin="0 2.5 0 2.5" />

Content.Client/UserInterface/Systems/EscapeMenu/EscapeUIController.cs

@@ -73,6 +73,12 @@ public void OnStateEntered(GameplayState state)
             if(_playerRoles.GetDiscordLink() is string link)
                 _uri.OpenUri(link);
         };
+
+        _escapeWindow.SteamButton.OnPressed += _ =>
+        {
+            if (_playerRoles.GetSteamLink() is string link)
+                _uri.OpenUri(link);
+        };
         // NullLink end
 
         _escapeWindow.ChangelogButton.OnPressed += _ =>

Content.Client/_NullLink/INullLinkPlayerRolesManager.cs

@@ -7,5 +7,6 @@ public interface INullLinkPlayerRolesManager
 
     bool ContainsAny(ulong[] roles);
     string? GetDiscordLink();
+    string? GetSteamLink();
     void Initialize();
 }

Content.Client/_NullLink/NullLinkPlayerRolesManager.cs

@@ -13,6 +13,7 @@ public sealed partial class NullLinkPlayerRolesManager : INullLinkPlayerRolesMan
 
     private ImmutableHashSet<ulong> _roles = [];
     private string? _discordLink;
+    private string? _steamLink;
     private ISawmill _sawmill = default!;
 
     public event Action PlayerRolesChanged = delegate { };
@@ -27,6 +28,7 @@ private void Update(MsgUpdatePlayerRoles message)
     {
         _roles = message.Roles;
         _discordLink = message.DiscordLink;
+        _steamLink = message.SteamLink;
 
         _sawmill.Info("Updated player roles");
         PlayerRolesChanged?.Invoke();
@@ -35,6 +37,9 @@ private void Update(MsgUpdatePlayerRoles message)
     public string? GetDiscordLink()
         => _discordLink;
 
+    public string? GetSteamLink()
+        => _steamLink;
+
     public bool ContainsAny(ulong[] roles)
         => roles.Any(_roles.Contains);
 }

Content.Server/_NullLink/PlayerData/INullLinkPlayerManager.cs

@@ -10,6 +10,7 @@ public interface INullLinkPlayerManager
     IEnumerable<ICommonSession> Mentors { get; }
 
     string GetDiscordAuthUrl(string customState);
+    string GetSteamAuthUrl(string customState);
     void Initialize();
     void Shutdown();
     ValueTask SyncPlayTime(PlayerServerPlayTimesSyncEvent playTimesSync);

Content.Server/_NullLink/PlayerData/NullLinkPlayerManager.Linking.cs

@@ -8,18 +8,27 @@ public sealed partial class NullLinkPlayerManager
     private const string _scope = "identify+guilds+guilds.members.read";
     private string? _discordKey;
     private string? _discordCallback;
+    private string? _steamAuth;
+    private string? _steamSecret;
     private string? _secret;
 
     public void InitializeLinking()
     {
         _discordKey = _cfg.GetCVar(StarlightCCVars.DiscordKey).Trim();
         _discordCallback = _cfg.GetCVar(StarlightCCVars.DiscordCallback).Trim();
         _secret = _cfg.GetCVar(StarlightCCVars.Secret);
+        _steamAuth = _cfg.GetCVar(StarlightCCVars.SteamBaseUrl);
+        _steamSecret = _cfg.GetCVar(StarlightCCVars.SteamSecret);
 
         if (!string.IsNullOrEmpty(_discordCallback)
             && (!Uri.TryCreate(_discordCallback, UriKind.Absolute, out var uri)
                 || uri.Scheme != Uri.UriSchemeHttp && uri.Scheme != Uri.UriSchemeHttps))
             _sawmill.Error($"discord.callback is not a valid absolute http(s) url: '{_discordCallback}'. discord linking will fail. set it to the exact redirect registered in the discord app, e.g. https://your.host/api/auth");
+
+        if (!string.IsNullOrEmpty(_steamAuth)
+            && (!Uri.TryCreate(_steamAuth, UriKind.Absolute, out var steamUri)
+                || steamUri.Scheme != Uri.UriSchemeHttp && steamUri.Scheme != Uri.UriSchemeHttps))
+            _sawmill.Error($"steam.baseurl is not a valid absolute http(s) url: '{_steamAuth}'. steam linking will fail. set it to the exact redirect registered in api, e.g. https://your.host/api/auth/steam");
     }
     public string GetDiscordAuthUrl(string customState)
     {
@@ -36,4 +45,20 @@ public string GetDiscordAuthUrl(string customState)
 
         return $"https://discord.com/api/oauth2/authorize?client_id={_discordKey}&redirect_uri={Uri.EscapeDataString(_discordCallback)}&response_type=code&scope={_scope}&state={encodedState}";
     }
+
+    public string GetSteamAuthUrl(string customState)
+    {
+        if (string.IsNullOrEmpty(_steamAuth) || string.IsNullOrEmpty(_steamSecret))
+            return "";
+
+        var secretKeyBytes = Encoding.UTF8.GetBytes(_steamSecret);
+        using var hmac = new HMACSHA256(secretKeyBytes);
+
+        var dataBytes = Encoding.UTF8.GetBytes(customState);
+        var hashBytes = hmac.ComputeHash(dataBytes);
+        var state = $"{customState}.{BitConverter.ToString(hashBytes).Replace("-", "").ToLower()}";
+        var encodedState = Uri.EscapeDataString(state);
+
+        return $"{_steamAuth}?state={encodedState}";
+    }
 }

Content.Server/_NullLink/PlayerData/NullLinkPlayerManager.Roles.cs

@@ -45,6 +45,7 @@ private void SendPlayerRoles(ICommonSession session, ImmutableHashSet<ulong> rol
     => _netMgr.ServerSendMessage(new MsgUpdatePlayerRoles
     {
         Roles = roles,
-        DiscordLink = GetDiscordAuthUrl(session.UserId.ToString())
+        DiscordLink = GetDiscordAuthUrl(session.UserId.ToString()),
+        SteamLink = GetSteamAuthUrl(session.UserId.ToString()),
     }, session.Channel);
 }

Content.Shared/_NullLink/MsgUpdatePlayerRoles.cs

@@ -10,10 +10,12 @@ public sealed class MsgUpdatePlayerRoles : NetMessage
 
     public ImmutableHashSet<ulong> Roles = [];
     public string? DiscordLink;
+    public string? SteamLink;
 
     public override void ReadFromBuffer(NetIncomingMessage buffer, IRobustSerializer serializer)
     {
         DiscordLink = buffer.ReadString();
+        SteamLink = buffer.ReadString();
 
         var length = buffer.ReadVariableInt32();
         var roles = new HashSet<ulong>(length);
@@ -26,6 +28,7 @@ public override void ReadFromBuffer(NetIncomingMessage buffer, IRobustSerializer
     public override void WriteToBuffer(NetOutgoingMessage buffer, IRobustSerializer serializer)
     {
         buffer.Write(DiscordLink);
+        buffer.Write(SteamLink);
 
         buffer.WriteVariableInt32(Roles.Count);
         foreach (var role in Roles)