add basic suppport for client_credentials oauth grant

Foxchat.Core/Federation/RequestSigningService.Client.cs

@@ -30,12 +30,12 @@ public partial class RequestSigningService
         if (!resp.IsSuccessStatusCode)
         {
             var error = await resp.Content.ReadAsStringAsync();
-            throw new FoxchatError.OutgoingFederationError($"Request to {domain}{requestPath} returned an error", DeserializeObject<Models.ApiError>(error));
+            throw new ApiError.OutgoingFederationError($"Request to {domain}{requestPath} returned an error", DeserializeObject<Models.ApiError>(error));
         }
 
         var bodyString = await resp.Content.ReadAsStringAsync();
         return DeserializeObject<T>(bodyString)
-            ?? throw new FoxchatError.OutgoingFederationError($"Request to {domain}{requestPath} returned invalid response body");
+            ?? throw new ApiError.OutgoingFederationError($"Request to {domain}{requestPath} returned invalid response body");
     }
 
     private HttpRequestMessage BuildHttpRequest(HttpMethod method, string domain, string requestPath, string? userId = null, object? bodyData = null)

Foxchat.Core/Federation/RequestSigningService.cs

@@ -5,16 +5,15 @@ using Foxchat.Core.Database;
 using Foxchat.Core.Utils;
 using NodaTime;
 using NodaTime.Text;
-using Serilog;
 
 namespace Foxchat.Core.Federation;
 
-public partial class RequestSigningService(ILogger logger, IClock clock, IDatabaseContext context, CoreConfig config)
+public partial class RequestSigningService(ILogger logger, IClock clock, IDatabaseContext db, CoreConfig config)
 {
     private readonly ILogger _logger = logger.ForContext<RequestSigningService>();
     private readonly IClock _clock = clock;
     private readonly CoreConfig _config = config;
-    private readonly RSA _rsa = context.GetInstanceKeysAsync().GetAwaiter().GetResult();
+    private readonly RSA _rsa = db.GetInstanceKeysAsync().GetAwaiter().GetResult();
     private readonly HttpClient _httpClient = new();
 
     public string GenerateSignature(SignatureData data)
@@ -41,11 +40,11 @@ public partial class RequestSigningService(ILogger logger, IClock clock, IDataba
         var time = ParseTime(dateHeader);
         if ((now + Duration.FromMinutes(1)) < time)
         {
-            throw new FoxchatError.IncomingFederationError("Request was made in the future");
+            throw new ApiError.IncomingFederationError("Request was made in the future");
         }
         else if ((now - Duration.FromMinutes(1)) > time)
         {
-            throw new FoxchatError.IncomingFederationError("Request was made too long ago");
+            throw new ApiError.IncomingFederationError("Request was made too long ago");
         }
 
         var plaintext = GeneratePlaintext(new SignatureData(time, host, requestPath, contentLength, userId));
@@ -54,7 +53,7 @@ public partial class RequestSigningService(ILogger logger, IClock clock, IDataba
 
         if (!CryptoUtils.TryFromBase64String(encodedSignature, out var signature))
         {
-            throw new FoxchatError.IncomingFederationError("Invalid base64 signature");
+            throw new ApiError.IncomingFederationError("Invalid base64 signature");
         }
 
         var deformatter = new RSAPKCS1SignatureDeformatter(rsa);

Foxchat.Core/FoxchatError.cs

@@ -4,18 +4,8 @@ namespace Foxchat.Core;
 
 public class FoxchatError(string message) : Exception(message)
 {
-    public class BadRequest(string message) : ApiError(message, statusCode: HttpStatusCode.BadRequest);
-    public class IncomingFederationError(string message) : ApiError(message, statusCode: HttpStatusCode.BadRequest);
-
-    public class OutgoingFederationError(
-        string message, Models.ApiError? innerError = null
-    ) : ApiError(message, statusCode: HttpStatusCode.InternalServerError)
-    {
-        public Models.ApiError? InnerError => innerError;
-    }
-
     public class DatabaseError(string message) : FoxchatError(message);
-    public class AuthenticationError(string message) : ApiError(message, statusCode: HttpStatusCode.BadRequest);
+    public class UnknownEntityError(Type entityType) : FoxchatError($"Entity of type {entityType.Name} not found");
 }
 
 public class ApiError(string message, HttpStatusCode? statusCode = null) : FoxchatError(message)
@@ -28,4 +18,16 @@ public class ApiError(string message, HttpStatusCode? statusCode = null) : Foxch
     {
         public readonly string[] Scopes = scopes?.ToArray() ?? [];
     }
+
+    public class BadRequest(string message) : ApiError(message, statusCode: HttpStatusCode.BadRequest);
+    public class IncomingFederationError(string message) : ApiError(message, statusCode: HttpStatusCode.BadRequest);
+
+    public class OutgoingFederationError(
+        string message, Models.ApiError? innerError = null
+    ) : ApiError(message, statusCode: HttpStatusCode.InternalServerError)
+    {
+        public Models.ApiError? InnerError => innerError;
+    }
+
+    public class AuthenticationError(string message) : ApiError(message, statusCode: HttpStatusCode.BadRequest);
 }

Foxchat.Core/Models/Hello.cs

@@ -1,6 +0,0 @@
-namespace Foxchat.Core.Models;
-
-public record HelloRequest(string Host);
-public record HelloResponse(string PublicKey, string Host);
-public record NodeInfo(string Software, string PublicKey);
-public record NodeSoftware(string Name, string? Version);

Foxchat.Core/Models/Http/Apps.cs

@@ -0,0 +1,8 @@
+namespace Foxchat.Core.Models.Http;
+
+public static class Apps
+{
+    public record CreateRequest(string Name, string[] Scopes, string[] RedirectUris);
+    public record CreateResponse(Ulid Id, string ClientId, string ClientSecret, string Name, string[] Scopes, string[] RedirectUris);
+    public record GetSelfResponse(Ulid Id, string ClientId, string? ClientSecret, string Name, string[] Scopes, string[] RedirectUris);
+}

Foxchat.Core/Models/Http/Hello.cs

@@ -0,0 +1,9 @@
+namespace Foxchat.Core.Models.Http;
+
+public static class Hello
+{
+    public record HelloRequest(string Host);
+    public record HelloResponse(string PublicKey, string Host);
+    public record NodeInfo(string Software, string PublicKey);
+    public record NodeSoftware(string Name, string? Version);
+}

Foxchat.Identity/Authorization/AuthenticationMiddleware.cs

@@ -63,7 +63,7 @@ public static class HttpContextExtensions
     public static void SetToken(this HttpContext ctx, Token token) => ctx.Items.Add(Key, token);
     public static Account? GetAccount(this HttpContext ctx) => ctx.GetToken()?.Account;
     public static Account GetAccountOrThrow(this HttpContext ctx) =>
-        ctx.GetAccount() ?? throw new FoxchatError.AuthenticationError("No account in HttpContext");
+        ctx.GetAccount() ?? throw new ApiError.AuthenticationError("No account in HttpContext");
 
     public static Token? GetToken(this HttpContext ctx)
     {

Foxchat.Identity/Controllers/NodeController.cs

@@ -1,4 +1,4 @@
-using Foxchat.Core.Models;
+using Foxchat.Core.Models.Http;
 using Foxchat.Identity.Database;
 using Foxchat.Identity.Services;
 using Microsoft.AspNetCore.Mvc;
@@ -7,15 +7,15 @@ namespace Foxchat.Identity.Controllers;
 
 [ApiController]
 [Route("/_fox/ident/node")]
-public class NodeController(IdentityContext context, ChatInstanceResolverService chatInstanceResolverService) : ControllerBase
+public class NodeController(IdentityContext db, ChatInstanceResolverService chatInstanceResolverService) : ControllerBase
 {
     public const string SOFTWARE_NAME = "Foxchat.NET.Identity";
 
     [HttpGet]
     public async Task<IActionResult> GetNode()
     {
-        var instance = await context.GetInstanceAsync();
-        return Ok(new NodeInfo(SOFTWARE_NAME, instance.PublicKey));
+        var instance = await db.GetInstanceAsync();
+        return Ok(new Hello.NodeInfo(SOFTWARE_NAME, instance.PublicKey));
     }
 
     [HttpGet("{domain}")]

Foxchat.Identity/Controllers/Oauth/AppsController.cs

@@ -0,0 +1,45 @@
+using Foxchat.Core;
+using Foxchat.Core.Models.Http;
+using Foxchat.Identity.Authorization;
+using Foxchat.Identity.Database;
+using Foxchat.Identity.Database.Models;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Foxchat.Identity.Controllers.Oauth;
+
+[ApiController]
+[Authenticate]
+[Route("/_fox/ident/oauth/apps")]
+public class AppsController(ILogger logger, IdentityContext db) : ControllerBase
+{
+    [HttpPost]
+    public async Task<IActionResult> CreateApplication([FromBody] Apps.CreateRequest req)
+    {
+        var app = Application.Create(req.Name, req.Scopes, req.RedirectUris);
+        await db.AddAsync(app);
+        await db.SaveChangesAsync();
+
+        logger.Information("Created new application {Name} with ID {Id} and client ID {ClientId}", app.Name, app.Id, app.ClientId);
+
+        return Ok(new Apps.CreateResponse(
+            app.Id, app.ClientId, app.ClientSecret, app.Name, app.Scopes, app.RedirectUris
+        ));
+    }
+
+    [HttpGet]
+    public IActionResult GetSelfApp([FromQuery(Name = "with_secret")] bool withSecret)
+    {
+        var token = HttpContext.GetToken();
+        if (token is not { Account: null }) throw new ApiError.Forbidden("This endpoint requires a client token.");
+        var app = token.Application;
+
+        return Ok(new Apps.GetSelfResponse(
+            app.Id,
+            app.ClientId,
+            withSecret ? app.ClientSecret : null,
+            app.Name,
+            app.Scopes,
+            app.RedirectUris
+        ));
+    }
+}

Foxchat.Identity/Controllers/Oauth/TokenController.cs

@@ -0,0 +1,73 @@
+using Foxchat.Core;
+using Foxchat.Identity.Database;
+using Foxchat.Identity.Database.Models;
+using Microsoft.AspNetCore.Mvc;
+using NodaTime;
+
+namespace Foxchat.Identity.Controllers.Oauth;
+
+[ApiController]
+[Route("/_fox/ident/oauth/token")]
+public class TokenController(ILogger logger, IdentityContext db, IClock clock) : ControllerBase
+{
+    [HttpPost]
+    public async Task<IActionResult> PostToken([FromBody] PostTokenRequest req)
+    {
+        var app = await db.GetApplicationAsync(req.ClientId, req.ClientSecret);
+
+        var scopes = req.Scope.Split(' ');
+        if (app.Scopes.Except(scopes).Any())
+        {
+            throw new ApiError.BadRequest("Invalid or unauthorized scopes");
+        }
+
+        switch (req.GrantType)
+        {
+            case "client_credentials":
+                return await HandleClientCredentialsAsync(app, scopes);
+            case "authorization_code":
+                break;
+            default:
+                throw new ApiError.BadRequest("Unknown grant_type");
+        }
+
+        throw new NotImplementedException();
+    }
+
+    private async Task<IActionResult> HandleClientCredentialsAsync(Application app, string[] scopes)
+    {
+        // TODO: make this configurable
+        var expiry = clock.GetCurrentInstant() + Duration.FromDays(365);
+        var (token, hash) = Token.Generate();
+        var tokenObj = new Token
+        {
+            Hash = hash,
+            Scopes = scopes,
+            Expires = expiry,
+            ApplicationId = app.Id
+        };
+
+        await db.AddAsync(tokenObj);
+        await db.SaveChangesAsync();
+
+        logger.Debug("Created token with scopes {Scopes} for application {ApplicationId}", scopes, app.Id);
+
+        return Ok(new PostTokenResponse(token, scopes, expiry));
+    }
+
+    public record PostTokenRequest(
+        string GrantType,
+        string ClientId,
+        string ClientSecret,
+        string Scope,
+        // Optional parameters
+        string? Code,
+        string? RedirectUri
+    );
+
+    public record PostTokenResponse(
+        string Token,
+        string[] Scopes,
+        Instant Expires
+    );
+}

Foxchat.Identity/Database/Models/Application.cs

@@ -1,5 +1,8 @@
 using System.Security.Cryptography;
+using Foxchat.Core;
+using Foxchat.Identity.Utils;
 using Microsoft.AspNetCore.WebUtilities;
+using Microsoft.EntityFrameworkCore;
 
 namespace Foxchat.Identity.Database.Models;
 
@@ -9,38 +12,47 @@ public class Application : BaseModel
     public required string ClientSecret { get; init; }
     public required string Name { get; init; }
     public required string[] Scopes { get; init; }
+    public required string[] RedirectUris { get; set; }
 
-    public static Application Create(string name, string[] scopes)
+    public static Application Create(string name, string[] scopes, string[] redirectUrls)
     {
-        var clientId = RandomNumberGenerator.GetHexString(16, true);
+        var clientId = RandomNumberGenerator.GetHexString(32, true);
         var clientSecretBytes = RandomNumberGenerator.GetBytes(48);
         var clientSecret = WebEncoders.Base64UrlEncode(clientSecretBytes);
 
-        if (!scopes.All(s => Scope.ValidScopes.Contains(s)))
+        if (scopes.Any(s => !OauthUtils.Scopes.Contains(s)))
         {
             throw new ArgumentException("Invalid scopes passed to Application.Create", nameof(scopes));
         }
 
+        if (redirectUrls.Any(s => !OauthUtils.ValidateRedirectUri(s)))
+        {
+            throw new ArgumentException("Invalid redirect URLs passed to Application.Create", nameof(redirectUrls));
+        }
+
         return new Application
         {
             ClientId = clientId,
             ClientSecret = clientSecret,
             Name = name,
             Scopes = scopes,
+            RedirectUris = redirectUrls
         };
     }
 }
 
-public static class Scope
+public static class ContextApplicationExtensions
 {
-    /// <summary>
-    /// OAuth scope for identifying a user and nothing else.
-    /// </summary>
-    public const string Identity = "identity";
-    /// <summary>
-    /// OAuth scope for a full chat client. This grants *full access* to an account.
-    /// </summary>
-    public const string ChatClient = "chat_client";
+    public static async Task<Application> GetApplicationAsync(this IdentityContext db, string clientId)
+    {
+        return await db.Applications.FirstOrDefaultAsync(a => a.ClientId == clientId)
+            ?? throw new ApiError.Unauthorized("Invalid client ID or client secret");
+    }
 
-    public static readonly string[] ValidScopes = [Identity, ChatClient];
+    public static async Task<Application> GetApplicationAsync(this IdentityContext db, string clientId, string clientSecret)
+    {
+        var app = await db.GetApplicationAsync(clientId);
+        if (app.ClientSecret != clientSecret) throw new ApiError.Unauthorized("Invalid client ID or client secret");
+        return app;
+    }
 }

Foxchat.Identity/Database/Models/Token.cs

@@ -10,8 +10,9 @@ public class Token : BaseModel
     public string[] Scopes { get; set; } = [];
     public Instant Expires { get; set; }
 
-    public Ulid AccountId { get; set; }
-    public Account Account { get; set; } = null!;
+    // Tokens can be granted directly to applications with `client_credentials`
+    public Ulid? AccountId { get; set; }
+    public Account? Account { get; set; }
 
     public Ulid ApplicationId { get; set; }
     public Application Application { get; set; } = null!;

Foxchat.Identity/Extensions/WebApplicationExtensions.cs

@@ -4,6 +4,13 @@ namespace Foxchat.Identity.Extensions;
 
 public static class WebApplicationExtensions
 {
+    public static IServiceCollection AddCustomMiddleware(this IServiceCollection services)
+    {
+        return services
+            .AddScoped<AuthenticationMiddleware>()
+            .AddScoped<AuthorizationMiddleware>();
+    }
+
     public static IApplicationBuilder UseCustomMiddleware(this IApplicationBuilder app)
     {
         return app

Foxchat.Identity/Migrations/20240520141853_AddRedirectUris.Designer.cs

@@ -0,0 +1,323 @@
+// <auto-generated />
+using System;
+using Foxchat.Identity.Database;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using NodaTime;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace Foxchat.Identity.Migrations
+{
+    [DbContext(typeof(IdentityContext))]
+    [Migration("20240520141853_AddRedirectUris")]
+    partial class AddRedirectUris
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "8.0.4")
+                .HasAnnotation("Relational:MaxIdentifierLength", 63);
+
+            NpgsqlModelBuilderExtensions.UseIdentityByDefaultColumns(modelBuilder);
+
+            modelBuilder.Entity("AccountChatInstance", b =>
+                {
+                    b.Property<Guid>("AccountsId")
+                        .HasColumnType("uuid")
+                        .HasColumnName("accounts_id");
+
+                    b.Property<Guid>("ChatInstancesId")
+                        .HasColumnType("uuid")
+                        .HasColumnName("chat_instances_id");
+
+                    b.HasKey("AccountsId", "ChatInstancesId")
+                        .HasName("pk_account_chat_instance");
+
+                    b.HasIndex("ChatInstancesId")
+                        .HasDatabaseName("ix_account_chat_instance_chat_instances_id");
+
+                    b.ToTable("account_chat_instance", (string)null);
+                });
+
+            modelBuilder.Entity("Foxchat.Core.Database.Instance", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasColumnName("id");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("Id"));
+
+                    b.Property<string>("PrivateKey")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("private_key");
+
+                    b.Property<string>("PublicKey")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("public_key");
+
+                    b.HasKey("Id")
+                        .HasName("pk_instance");
+
+                    b.ToTable("instance", (string)null);
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.Account", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .HasColumnType("uuid")
+                        .HasColumnName("id");
+
+                    b.Property<string>("Avatar")
+                        .HasColumnType("text")
+                        .HasColumnName("avatar");
+
+                    b.Property<string>("Email")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("email");
+
+                    b.Property<string>("Password")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("password");
+
+                    b.Property<int>("Role")
+                        .HasColumnType("integer")
+                        .HasColumnName("role");
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("username");
+
+                    b.HasKey("Id")
+                        .HasName("pk_accounts");
+
+                    b.HasIndex("Email")
+                        .IsUnique()
+                        .HasDatabaseName("ix_accounts_email");
+
+                    b.HasIndex("Username")
+                        .IsUnique()
+                        .HasDatabaseName("ix_accounts_username");
+
+                    b.ToTable("accounts", (string)null);
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.Application", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .HasColumnType("uuid")
+                        .HasColumnName("id");
+
+                    b.Property<string>("ClientId")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("client_id");
+
+                    b.Property<string>("ClientSecret")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("client_secret");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("name");
+
+                    b.Property<string[]>("RedirectUris")
+                        .IsRequired()
+                        .HasColumnType("text[]")
+                        .HasColumnName("redirect_uris");
+
+                    b.Property<string[]>("Scopes")
+                        .IsRequired()
+                        .HasColumnType("text[]")
+                        .HasColumnName("scopes");
+
+                    b.HasKey("Id")
+                        .HasName("pk_applications");
+
+                    b.HasIndex("ClientId")
+                        .IsUnique()
+                        .HasDatabaseName("ix_applications_client_id");
+
+                    b.ToTable("applications", (string)null);
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.ChatInstance", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .HasColumnType("uuid")
+                        .HasColumnName("id");
+
+                    b.Property<string>("BaseUrl")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("base_url");
+
+                    b.Property<string>("Domain")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("domain");
+
+                    b.Property<string>("PublicKey")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("public_key");
+
+                    b.Property<string>("Reason")
+                        .HasColumnType("text")
+                        .HasColumnName("reason");
+
+                    b.Property<int>("Status")
+                        .HasColumnType("integer")
+                        .HasColumnName("status");
+
+                    b.HasKey("Id")
+                        .HasName("pk_chat_instances");
+
+                    b.HasIndex("Domain")
+                        .IsUnique()
+                        .HasDatabaseName("ix_chat_instances_domain");
+
+                    b.ToTable("chat_instances", (string)null);
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.GuildAccount", b =>
+                {
+                    b.Property<Guid>("ChatInstanceId")
+                        .HasColumnType("uuid")
+                        .HasColumnName("chat_instance_id");
+
+                    b.Property<string>("GuildId")
+                        .HasColumnType("text")
+                        .HasColumnName("guild_id");
+
+                    b.Property<Guid>("AccountId")
+                        .HasColumnType("uuid")
+                        .HasColumnName("account_id");
+
+                    b.HasKey("ChatInstanceId", "GuildId", "AccountId")
+                        .HasName("pk_guild_accounts");
+
+                    b.HasIndex("AccountId")
+                        .HasDatabaseName("ix_guild_accounts_account_id");
+
+                    b.ToTable("guild_accounts", (string)null);
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.Token", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .HasColumnType("uuid")
+                        .HasColumnName("id");
+
+                    b.Property<Guid?>("AccountId")
+                        .HasColumnType("uuid")
+                        .HasColumnName("account_id");
+
+                    b.Property<Guid>("ApplicationId")
+                        .HasColumnType("uuid")
+                        .HasColumnName("application_id");
+
+                    b.Property<Instant>("Expires")
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("expires");
+
+                    b.Property<byte[]>("Hash")
+                        .IsRequired()
+                        .HasColumnType("bytea")
+                        .HasColumnName("hash");
+
+                    b.Property<string[]>("Scopes")
+                        .IsRequired()
+                        .HasColumnType("text[]")
+                        .HasColumnName("scopes");
+
+                    b.HasKey("Id")
+                        .HasName("pk_tokens");
+
+                    b.HasIndex("AccountId")
+                        .HasDatabaseName("ix_tokens_account_id");
+
+                    b.HasIndex("ApplicationId")
+                        .HasDatabaseName("ix_tokens_application_id");
+
+                    b.ToTable("tokens", (string)null);
+                });
+
+            modelBuilder.Entity("AccountChatInstance", b =>
+                {
+                    b.HasOne("Foxchat.Identity.Database.Models.Account", null)
+                        .WithMany()
+                        .HasForeignKey("AccountsId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired()
+                        .HasConstraintName("fk_account_chat_instance_accounts_accounts_id");
+
+                    b.HasOne("Foxchat.Identity.Database.Models.ChatInstance", null)
+                        .WithMany()
+                        .HasForeignKey("ChatInstancesId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired()
+                        .HasConstraintName("fk_account_chat_instance_chat_instances_chat_instances_id");
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.GuildAccount", b =>
+                {
+                    b.HasOne("Foxchat.Identity.Database.Models.Account", "Account")
+                        .WithMany()
+                        .HasForeignKey("AccountId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired()
+                        .HasConstraintName("fk_guild_accounts_accounts_account_id");
+
+                    b.HasOne("Foxchat.Identity.Database.Models.ChatInstance", "ChatInstance")
+                        .WithMany()
+                        .HasForeignKey("ChatInstanceId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired()
+                        .HasConstraintName("fk_guild_accounts_chat_instances_chat_instance_id");
+
+                    b.Navigation("Account");
+
+                    b.Navigation("ChatInstance");
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.Token", b =>
+                {
+                    b.HasOne("Foxchat.Identity.Database.Models.Account", "Account")
+                        .WithMany("Tokens")
+                        .HasForeignKey("AccountId")
+                        .HasConstraintName("fk_tokens_accounts_account_id");
+
+                    b.HasOne("Foxchat.Identity.Database.Models.Application", "Application")
+                        .WithMany()
+                        .HasForeignKey("ApplicationId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired()
+                        .HasConstraintName("fk_tokens_applications_application_id");
+
+                    b.Navigation("Account");
+
+                    b.Navigation("Application");
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.Account", b =>
+                {
+                    b.Navigation("Tokens");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

Foxchat.Identity/Migrations/20240520141853_AddRedirectUris.cs

@@ -0,0 +1,71 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Foxchat.Identity.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddRedirectUris : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "fk_tokens_accounts_account_id",
+                table: "tokens");
+
+            migrationBuilder.AlterColumn<Guid>(
+                name: "account_id",
+                table: "tokens",
+                type: "uuid",
+                nullable: true,
+                oldClrType: typeof(Guid),
+                oldType: "uuid");
+
+            migrationBuilder.AddColumn<string[]>(
+                name: "redirect_uris",
+                table: "applications",
+                type: "text[]",
+                nullable: false,
+                defaultValue: new string[0]);
+
+            migrationBuilder.AddForeignKey(
+                name: "fk_tokens_accounts_account_id",
+                table: "tokens",
+                column: "account_id",
+                principalTable: "accounts",
+                principalColumn: "id");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "fk_tokens_accounts_account_id",
+                table: "tokens");
+
+            migrationBuilder.DropColumn(
+                name: "redirect_uris",
+                table: "applications");
+
+            migrationBuilder.AlterColumn<Guid>(
+                name: "account_id",
+                table: "tokens",
+                type: "uuid",
+                nullable: false,
+                defaultValue: new Guid("00000000-0000-0000-0000-000000000000"),
+                oldClrType: typeof(Guid),
+                oldType: "uuid",
+                oldNullable: true);
+
+            migrationBuilder.AddForeignKey(
+                name: "fk_tokens_accounts_account_id",
+                table: "tokens",
+                column: "account_id",
+                principalTable: "accounts",
+                principalColumn: "id",
+                onDelete: ReferentialAction.Cascade);
+        }
+    }
+}

Foxchat.Identity/Migrations/IdentityContextModelSnapshot.cs

@@ -131,6 +131,11 @@ namespace Foxchat.Identity.Migrations
                         .HasColumnType("text")
                         .HasColumnName("name");
 
+                    b.Property<string[]>("RedirectUris")
+                        .IsRequired()
+                        .HasColumnType("text[]")
+                        .HasColumnName("redirect_uris");
+
                     b.Property<string[]>("Scopes")
                         .IsRequired()
                         .HasColumnType("text[]")
@@ -214,7 +219,7 @@ namespace Foxchat.Identity.Migrations
                         .HasColumnType("uuid")
                         .HasColumnName("id");
 
-                    b.Property<Guid>("AccountId")
+                    b.Property<Guid?>("AccountId")
                         .HasColumnType("uuid")
                         .HasColumnName("account_id");
 
@@ -291,8 +296,6 @@ namespace Foxchat.Identity.Migrations
                     b.HasOne("Foxchat.Identity.Database.Models.Account", "Account")
                         .WithMany("Tokens")
                         .HasForeignKey("AccountId")
-                        .OnDelete(DeleteBehavior.Cascade)
-                        .IsRequired()
                         .HasConstraintName("fk_tokens_accounts_account_id");
 
                     b.HasOne("Foxchat.Identity.Database.Models.Application", "Application")

Foxchat.Identity/Program.cs

@@ -26,19 +26,18 @@ builder.Services
 builder.Services
     .AddCoreServices<IdentityContext>()
     .AddScoped<ChatInstanceResolverService>()
+    .AddCustomMiddleware()
     .AddEndpointsApiExplorer()
     .AddSwaggerGen();
 
 var app = builder.Build();
 
 app.UseSerilogRequestLogging();
-app.UseCustomMiddleware();
 app.UseRouting();
 app.UseSwagger();
 app.UseSwaggerUI();
 app.UseCors();
-app.UseAuthentication();
-app.UseAuthorization();
+app.UseCustomMiddleware();
 app.MapControllers();
 
 using (var scope = app.Services.CreateScope())

Foxchat.Identity/Services/ChatInstanceResolverService.cs

@@ -1,27 +1,27 @@
 using Foxchat.Core.Federation;
-using Foxchat.Core.Models;
+using Foxchat.Core.Models.Http;
 using Foxchat.Identity.Database;
 using Foxchat.Identity.Database.Models;
 using Microsoft.EntityFrameworkCore;
 
 namespace Foxchat.Identity.Services;
 
-public class ChatInstanceResolverService(ILogger logger, RequestSigningService requestSigningService, IdentityContext context, InstanceConfig config)
+public class ChatInstanceResolverService(ILogger logger, RequestSigningService requestSigningService, IdentityContext db, InstanceConfig config)
 {
     private readonly ILogger _logger = logger.ForContext<ChatInstanceResolverService>();
 
     public async Task<ChatInstance> ResolveChatInstanceAsync(string domain)
     {
-        var instance = await context.ChatInstances.Where(c => c.Domain == domain).FirstOrDefaultAsync();
+        var instance = await db.ChatInstances.Where(c => c.Domain == domain).FirstOrDefaultAsync();
         if (instance != null) return instance;
 
         _logger.Information("Unknown chat instance {Domain}, fetching its data", domain);
 
-        var resp = await requestSigningService.RequestAsync<HelloResponse>(
+        var resp = await requestSigningService.RequestAsync<Hello.HelloResponse>(
             HttpMethod.Post,
             domain, "/_fox/chat/hello",
             userId: null,
-            body: new HelloRequest(config.Domain)
+            body: new Hello.HelloRequest(config.Domain)
         );
 
         instance = new ChatInstance
@@ -31,8 +31,8 @@ public class ChatInstanceResolverService(ILogger logger, RequestSigningService r
             PublicKey = resp.PublicKey,
             Status = ChatInstance.InstanceStatus.Active,
         };
-        await context.AddAsync(instance);
-        await context.SaveChangesAsync();
+        await db.AddAsync(instance);
+        await db.SaveChangesAsync();
 
         return instance;
     }

Foxchat.Identity/Utils/OauthUtils.cs

@@ -0,0 +1,23 @@
+namespace Foxchat.Identity.Utils;
+
+public static class OauthUtils
+{
+    public static readonly string[] Scopes = ["identify", "chat_client"];
+
+    private static readonly string[] ForbiddenSchemes = ["javascript", "file", "data", "mailto", "tel"];
+    private const string OobUri = "urn:ietf:wg:oauth:2.0:oob";
+
+    public static bool ValidateRedirectUri(string uri)
+    {
+        if (uri == OobUri) return true;
+        try
+        {
+            var scheme = new Uri(uri).Scheme;
+            return !ForbiddenSchemes.Contains(scheme);
+        }
+        catch
+        {
+            return false;
+        }
+    }
+}