init

.editorconfig

@@ -0,0 +1,4 @@
+[*.cs]
+
+# CS9113: Parameter is unread.
+dotnet_diagnostic.CS9113.severity = silent

.gitignore

@@ -0,0 +1,3 @@
+bin/
+obj/
+.version

Foxchat.Core/BuildInfo.cs

@@ -0,0 +1,24 @@
+namespace Foxchat.Core;
+
+public static class BuildInfo
+{
+    public static string Hash { get; private set; } = "(unknown)";
+    public static string Version { get; private set; } = "(unknown)";
+
+    public static async Task ReadBuildInfo()
+    {
+        await using var stream = typeof(BuildInfo).Assembly.GetManifestResourceStream("version");
+        if (stream == null) return;
+
+        using var reader = new StreamReader(stream);
+        var data = (await reader.ReadToEndAsync()).Trim().Split("\n");
+
+        Hash = data[0];
+        var dirty = data[2] == "dirty";
+
+        var versionData = data[1].Split("-");
+        Version = versionData[0];
+        if (versionData[1] != "0" || dirty) Version += $"+{versionData[2]}";
+        if (dirty) Version += ".dirty";
+    }
+}

Foxchat.Core/CoreConfig.cs

@@ -0,0 +1,24 @@
+using Serilog.Events;
+
+namespace Foxchat.Core;
+
+public class CoreConfig
+{
+    public string Host { get; set; } = "localhost";
+    public int Port { get; set; } = 3000;
+    public bool Secure { get; set; } = false;
+    public string Domain { get; set; } = null!;
+
+    public string Address => $"{(Secure ? "https" : "http")}://{Host}:{Port}";
+
+    public LogEventLevel LogEventLevel { get; set; } = LogEventLevel.Debug;
+
+    public DatabaseConfig Database { get; set; } = new();
+
+    public class DatabaseConfig
+    {
+        public string Url { get; set; } = string.Empty;
+        public int? Timeout { get; set; }
+        public int? MaxPoolSize { get; set; }
+    }
+}

Foxchat.Core/Database/IDatabaseContext.cs

@@ -0,0 +1,44 @@
+using System.Security.Cryptography;
+using Microsoft.EntityFrameworkCore;
+
+namespace Foxchat.Core.Database;
+
+public abstract class IDatabaseContext : DbContext
+{
+    public virtual DbSet<Instance> Instance { get; set; }
+
+    public async ValueTask<bool> InitializeInstanceAsync(CancellationToken ct = default)
+    {
+        var instance = await Instance.Where(i => i.Id == 1).FirstOrDefaultAsync(ct);
+        if (instance != null) return false;
+
+        var rsa = RSA.Create();
+        var publicKey = rsa.ExportRSAPublicKeyPem();
+        var privateKey = rsa.ExportRSAPrivateKeyPem();
+
+        await Instance.AddAsync(new Instance
+        {
+            PublicKey = publicKey!,
+            PrivateKey = privateKey!,
+        }, ct);
+
+        await SaveChangesAsync(ct);
+        return true;
+    }
+
+    public async Task<Instance> GetInstanceAsync(CancellationToken ct = default)
+    {
+        var instance = await Instance.FirstOrDefaultAsync(ct)
+            ?? throw new Exception("GetInstanceAsync called without Instance being initialized"); // TODO: replace this with specific exception type
+        return instance;
+    }
+
+    public async Task<RSA> GetInstanceKeysAsync(CancellationToken ct = default)
+    {
+        var instance = await GetInstanceAsync(ct);
+
+        var rsa = RSA.Create();
+        rsa.ImportFromPem(instance.PrivateKey);
+        return rsa;
+    }
+}

Foxchat.Core/Database/Instance.cs

@@ -0,0 +1,8 @@
+namespace Foxchat.Core.Database;
+
+public class Instance
+{
+    public int Id { get; init; }
+    public string PublicKey { get; set; } = null!;
+    public string PrivateKey { get; set; } = null!;
+}

Foxchat.Core/Federation/RequestSigningService.Client.cs

@@ -0,0 +1,72 @@
+using System.Net.Http.Headers;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+
+namespace Foxchat.Core.Federation;
+
+public partial class RequestSigningService
+{
+    public const string USER_AGENT_HEADER = "User-Agent";
+    public const string USER_AGENT = "Foxchat.NET";
+    public const string DATE_HEADER = "Date";
+    public const string CONTENT_LENGTH_HEADER = "Content-Length";
+    public const string CONTENT_TYPE_HEADER = "Content-Type";
+    public const string CONTENT_TYPE = "application/json; charset=utf-8";
+
+    public const string SERVER_HEADER = "X-Foxchat-Server";
+    public const string SIGNATURE_HEADER = "X-Foxchat-Signature";
+    public const string USER_HEADER = "X-Foxchat-User";
+
+    private static readonly JsonSerializerSettings _jsonSerializerSettings = new()
+    {
+        ContractResolver = new DefaultContractResolver
+        {
+            NamingStrategy = new SnakeCaseNamingStrategy()
+        }
+    };
+
+    public async Task<T> RequestAsync<T>(HttpMethod method, string domain, string requestPath, string? userId = null, object? body = null)
+    {
+        var request = BuildHttpRequest(method, domain, requestPath, userId, body);
+        _logger.Debug("Content length in header: '{ContentLength}'", request.Headers.Where(c => c.Key == "Content-Length"));
+        var resp = await _httpClient.SendAsync(request);
+        if (!resp.IsSuccessStatusCode)
+        {
+            var error = await resp.Content.ReadAsStringAsync();
+            _logger.Error("Received {Status}, body: {Error}", resp.StatusCode, error);
+            // TODO: replace this with specific exception type
+            throw new Exception("oh no a request error");
+        }
+
+        var bodyString = await resp.Content.ReadAsStringAsync();
+        // TODO: replace this with specific exception type
+        return DeserializeObject<T>(bodyString) ?? throw new Exception("oh no invalid json");
+    }
+
+    private HttpRequestMessage BuildHttpRequest(HttpMethod method, string domain, string requestPath, string? userId = null, object? bodyData = null)
+    {
+        var body = bodyData != null ? SerializeObject(bodyData) : null;
+
+        var now = _clock.GetCurrentInstant();
+        var url = $"https://{domain}{requestPath}";
+        var signature = GenerateSignature(new SignatureData(now, domain, requestPath, body?.Length, userId));
+
+        var request = new HttpRequestMessage(method, url);
+        request.Headers.Clear();
+        request.Headers.Add(USER_AGENT_HEADER, USER_AGENT);
+        request.Headers.Add(DATE_HEADER, FormatTime(now));
+        request.Headers.Add(SERVER_HEADER, _config.Domain);
+        request.Headers.Add(SIGNATURE_HEADER, signature);
+        if (userId != null)
+            request.Headers.Add(USER_HEADER, userId);
+        if (body != null)
+        {
+            request.Content = new StringContent(body, new MediaTypeHeaderValue("application/json", "utf-8"));
+        }
+
+        return request;
+    }
+
+    public static string SerializeObject(object data) => JsonConvert.SerializeObject(data, _jsonSerializerSettings);
+    public static T? DeserializeObject<T>(string data) => JsonConvert.DeserializeObject<T>(data, _jsonSerializerSettings);
+}

Foxchat.Core/Federation/RequestSigningService.cs

@@ -0,0 +1,78 @@
+using System.Globalization;
+using System.Security.Cryptography;
+using System.Text;
+using Foxchat.Core.Database;
+using Microsoft.AspNetCore.WebUtilities;
+using NodaTime;
+using NodaTime.Text;
+using Serilog;
+
+namespace Foxchat.Core.Federation;
+
+public partial class RequestSigningService(ILogger logger, IClock clock, IDatabaseContext context, 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 HttpClient _httpClient = new();
+
+    public string GenerateSignature(SignatureData data)
+    {
+        var plaintext = GeneratePlaintext(data);
+        var plaintextBytes = Encoding.UTF8.GetBytes(plaintext);
+        var hash = SHA256.HashData(plaintextBytes);
+
+        var formatter = new RSAPKCS1SignatureFormatter(_rsa);
+        formatter.SetHashAlgorithm(nameof(SHA256));
+        var signature = formatter.CreateSignature(hash);
+
+        _logger.Debug("Generated signature for {Host} {RequestPath}: {Signature}", data.Host, data.RequestPath, WebEncoders.Base64UrlEncode(signature));
+        return WebEncoders.Base64UrlEncode(signature);
+    }
+
+    public bool VerifySignature(
+        string publicKey, string encodedSignature, string dateHeader, string host, string requestPath, int? contentLength, string? userId)
+    {
+        var rsa = RSA.Create();
+        rsa.ImportFromPem(publicKey);
+
+        var now = _clock.GetCurrentInstant();
+        var time = ParseTime(dateHeader);
+        if ((now + Duration.FromMinutes(1)) < time)
+        {
+            // TODO: replace this with specific exception type
+            throw new Exception("Request was made in the future");
+        }
+        else if ((now - Duration.FromMinutes(1)) > time)
+        {
+            // TODO: replace this with specific exception type
+            throw new Exception("Request was made too long ago");
+        }
+
+        var plaintext = GeneratePlaintext(new SignatureData(time, host, requestPath, contentLength, userId));
+        var plaintextBytes = Encoding.UTF8.GetBytes(plaintext);
+        var hash = SHA256.HashData(plaintextBytes);
+        var signature = WebEncoders.Base64UrlDecode(encodedSignature);
+
+        var deformatter = new RSAPKCS1SignatureDeformatter(rsa);
+        deformatter.SetHashAlgorithm(nameof(SHA256));
+
+        return deformatter.VerifySignature(hash, signature);
+    }
+
+    private static string GeneratePlaintext(SignatureData data)
+    {
+        var time = FormatTime(data.Time);
+        var contentLength = data.ContentLength != null ? data.ContentLength.ToString() : "";
+        var userId = data.UserId ?? "";
+
+        Log.Information("Plaintext string: {Plaintext}", $"{time}:{data.Host}:{data.RequestPath}:{contentLength}:{userId}");
+
+        return $"{time}:{data.Host}:{data.RequestPath}:{contentLength}:{userId}";
+    }
+
+    private static readonly InstantPattern _pattern = InstantPattern.Create("ddd, dd MMM yyyy HH:mm:ss 'GMT'", CultureInfo.GetCultureInfo("en-US"));
+    private static string FormatTime(Instant time) => _pattern.Format(time);
+    private static Instant ParseTime(string header) => _pattern.Parse(header).GetValueOrThrow();
+}

Foxchat.Core/Federation/SignatureData.cs

@@ -0,0 +1,11 @@
+using NodaTime;
+
+namespace Foxchat.Core.Federation;
+
+public record SignatureData(
+    Instant Time,
+    string Host,
+    string RequestPath,
+    int? ContentLength,
+    string? UserId
+) { }

Foxchat.Core/Foxchat.Core.csproj

@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.4" />
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+    <PackageReference Include="NodaTime" Version="3.1.11" />
+    <PackageReference Include="NUlid" Version="1.7.2" />
+    <PackageReference Include="Serilog" Version="3.1.1" />
+    <PackageReference Include="Serilog.AspNetCore" Version="8.0.1" />
+    <PackageReference Include="Serilog.Sinks.Console" Version="5.0.1" />
+  </ItemGroup>
+
+  <Target Name="SetSourceRevisionId" BeforeTargets="InitializeSourceControlInformation">
+    <Exec Command="../build_info.sh" IgnoreExitCode="false">
+    </Exec>
+  </Target>
+
+  <ItemGroup>
+    <EmbeddedResource Include="..\.version" LogicalName="version" />
+  </ItemGroup>
+</Project>

Foxchat.Core/Models/Hello.cs

@@ -0,0 +1,6 @@
+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/ServiceCollectionExtensions.cs

@@ -0,0 +1,75 @@
+using Foxchat.Core.Database;
+using Foxchat.Core.Federation;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using NodaTime;
+using Serilog;
+using Serilog.Events;
+using Serilog.Sinks.SystemConsole.Themes;
+
+namespace Foxchat.Core;
+
+public static class ServiceCollectionExtensions
+{
+    /// <summary>
+    /// Adds Serilog to this service collection. This method also initializes Serilog so it should be called as early as possible, before any log calls.
+    /// </summary>
+    public static IServiceCollection AddSerilog(this IServiceCollection services, LogEventLevel level)
+    {
+        var logCfg = new LoggerConfiguration()
+            .Enrich.FromLogContext()
+            .MinimumLevel.Is(level)
+            // ASP.NET's built in request logs are extremely verbose, so we use Serilog's instead.
+            // Serilog doesn't disable the built in logs so we do it here.
+            .MinimumLevel.Override("Microsoft", LogEventLevel.Information)
+            .MinimumLevel.Override("Microsoft.AspNetCore.Hosting", LogEventLevel.Warning)
+            .MinimumLevel.Override("Microsoft.AspNetCore.Mvc", LogEventLevel.Warning)
+            .MinimumLevel.Override("Microsoft.AspNetCore.Routing", LogEventLevel.Warning)
+            .WriteTo.Console(theme: AnsiConsoleTheme.Code);
+
+        Log.Logger = logCfg.CreateLogger();
+
+        // AddSerilog doesn't seem to add an ILogger to the service collection, so add that manually.
+        return services.AddSerilog().AddSingleton(Log.Logger);
+    }
+
+    /// <summary>
+    /// Adds the core Foxchat services to this service collection.
+    /// </summary>
+    public static IServiceCollection AddCoreServices<T>(this IServiceCollection services) where T : IDatabaseContext
+    {
+        services.AddDbContext<T>();
+
+        // NodaTime recommends only depending on the IClock interface, not the singleton.
+        services.AddSingleton<IClock>(SystemClock.Instance);
+        // Some core services rely on an IDatabaseContext, not the server-specific context type.
+        services.AddScoped<IDatabaseContext, T>();
+        services.AddSingleton<RequestSigningService>();
+
+        return services;
+    }
+
+    public static T AddConfiguration<T>(this WebApplicationBuilder builder, string? configFile = null) where T : class, new()
+    {
+
+        builder.Configuration.Sources.Clear();
+        builder.Configuration.AddConfiguration(configFile);
+
+        var config = builder.Configuration.Get<T>() ?? new();
+        var coreConfig = builder.Configuration.Get<CoreConfig>() ?? new();
+        builder.Services.AddSingleton(config);
+        builder.Services.AddSingleton(coreConfig);
+        return config;
+    }
+
+    public static IConfigurationBuilder AddConfiguration(this IConfigurationBuilder builder, string? configFile = null)
+    {
+        var file = Environment.GetEnvironmentVariable("FOXCHAT_CONFIG_FILE") ?? configFile ?? "config.ini";
+
+        return builder
+            .SetBasePath(Directory.GetCurrentDirectory())
+            .AddIniFile(file, optional: false, reloadOnChange: true)
+            .AddEnvironmentVariables();
+    }
+}

Foxchat.Core/UlidConverter.cs

@@ -0,0 +1,10 @@
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using NUlid;
+
+namespace Foxchat.Core;
+
+public class UlidConverter() : ValueConverter<Ulid, Guid>(
+    convertToProviderExpression: x => x.ToGuid(),
+    convertFromProviderExpression: x => new Ulid(x)
+)
+{ }

Foxchat.Identity/Authorization/AuthenticationHandler.cs

@@ -0,0 +1,9 @@
+namespace Foxchat.Identity.Authorization;
+
+public static class AuthenticationHandlerExtensions
+{
+    public static void AddAuthenticationHandler(this IServiceCollection services)
+    {
+
+    }
+}

Foxchat.Identity/Controllers/NodeController.cs

@@ -0,0 +1,27 @@
+using Foxchat.Core.Models;
+using Foxchat.Identity.Database;
+using Foxchat.Identity.Services;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Foxchat.Identity.Controllers;
+
+[ApiController]
+[Route("/_fox/ident/node")]
+public class NodeController(IdentityContext context, 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));
+    }
+
+    [HttpGet("{domain}")]
+    public async Task<IActionResult> GetChatNode(string domain)
+    {
+        var instance = await chatInstanceResolverService.ResolveChatInstanceAsync(domain);
+        return Ok(instance);
+    }
+}

Foxchat.Identity/Database/IdentityContext.cs

@@ -0,0 +1,63 @@
+using Foxchat.Core;
+using Foxchat.Core.Database;
+using Foxchat.Identity.Database.Models;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Design;
+
+namespace Foxchat.Identity.Database;
+
+public class IdentityContext : IDatabaseContext
+{
+    private readonly string _connString;
+
+    public DbSet<Account> Accounts { get; set; }
+    public DbSet<ChatInstance> ChatInstances { get; set; }
+    public override DbSet<Instance> Instance { get; set; }
+    public DbSet<Token> Tokens { get; set; }
+    public DbSet<GuildAccount> GuildAccounts { get; set; }
+
+    public IdentityContext(InstanceConfig config)
+    {
+        _connString = new Npgsql.NpgsqlConnectionStringBuilder(config.Database.Url)
+        {
+            Timeout = config.Database.Timeout ?? 5,
+            MaxPoolSize = config.Database.MaxPoolSize ?? 50,
+        }.ConnectionString;
+    }
+
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+            => optionsBuilder
+                .UseNpgsql(_connString)
+                .UseSnakeCaseNamingConvention();
+
+    protected override void ConfigureConventions(ModelConfigurationBuilder configurationBuilder)
+    {
+        // ULIDs are stored as UUIDs in the database
+        configurationBuilder.Properties<Ulid>().HaveConversion<UlidConverter>();
+    }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<Account>().HasIndex(a => a.Username).IsUnique();
+        modelBuilder.Entity<Account>().HasIndex(a => a.Email).IsUnique();
+
+        modelBuilder.Entity<ChatInstance>().HasIndex(i => i.Domain).IsUnique();
+
+        modelBuilder.Entity<GuildAccount>().HasKey(g => new { g.ChatInstanceId, g.GuildId, g.AccountId });
+    }
+}
+
+public class DesignTimeIdentityContextFactory : IDesignTimeDbContextFactory<IdentityContext>
+{
+    public IdentityContext CreateDbContext(string[] args)
+    {
+        // Read the configuration file
+        var config = new ConfigurationBuilder()
+            .AddConfiguration("identity.ini")
+            .Build()
+            // Get the configuration as our config class
+            .Get<InstanceConfig>() ?? new();
+
+        return new IdentityContext(config);
+    }
+}

Foxchat.Identity/Database/Models/Account.cs

@@ -0,0 +1,21 @@
+namespace Foxchat.Identity.Database.Models;
+
+public class Account
+{
+    public Ulid Id { get; init; } = Ulid.NewUlid();
+    public string Username { get; set; } = null!;
+    public string Email { get; set; } = null!;
+    public string Password { get; set; } = null!;
+    public AccountRole Role { get; set; }
+
+    public string? Avatar { get; set; }
+
+    public List<Token> Tokens { get; } = [];
+    public List<ChatInstance> ChatInstances { get; } = [];
+
+    public enum AccountRole
+    {
+        User,
+        Admin,
+    }
+}

Foxchat.Identity/Database/Models/ChatInstance.cs

@@ -0,0 +1,19 @@
+namespace Foxchat.Identity.Database.Models;
+
+public class ChatInstance
+{
+    public Ulid Id { get; init; } = Ulid.NewUlid();
+    public string Domain { get; init; } = null!;
+    public string BaseUrl { get; set; } = null!;
+    public string PublicKey { get; set; } = null!;
+    public InstanceStatus Status { get; set; }
+    public string? Reason { get; set; }
+
+    public List<Account> Accounts { get; } = [];
+
+    public enum InstanceStatus
+    {
+        Active,
+        Suspended,
+    }
+}

Foxchat.Identity/Database/Models/GuildAccount.cs

@@ -0,0 +1,10 @@
+namespace Foxchat.Identity.Database.Models;
+
+public class GuildAccount
+{
+    public Ulid ChatInstanceId { get; init; }
+    public ChatInstance ChatInstance { get; init; } = null!;
+    public string GuildId { get; init; } = null!;
+    public Ulid AccountId { get; init; }
+    public Account Account { get; init; } = null!;
+}

Foxchat.Identity/Database/Models/Token.cs

@@ -0,0 +1,8 @@
+namespace Foxchat.Identity.Database.Models;
+
+public class Token
+{
+    public Ulid Id { get; init; } = Ulid.NewUlid();
+    public Ulid AccountId { get; set; }
+    public Account Account { get; set; } = null!;
+}

Foxchat.Identity/Foxchat.Identity.csproj

@@ -0,0 +1,29 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="EFCore.NamingConventions" Version="8.0.3" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="8.0.4" />
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.4" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.4" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="8.0.4">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="8.0.2" />
+    <PackageReference Include="Serilog" Version="3.1.1" />
+    <PackageReference Include="Serilog.AspNetCore" Version="8.0.1" />
+    <PackageReference Include="Serilog.Sinks.Console" Version="5.0.1" />
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.4.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Foxchat.Core\Foxchat.Core.csproj" />
+  </ItemGroup>
+</Project>

Foxchat.Identity/GlobalUsing.cs

@@ -0,0 +1,3 @@
+global using ILogger = Serilog.ILogger;
+global using Log = Serilog.Log;
+global using NUlid;

Foxchat.Identity/InstanceConfig.cs

@@ -0,0 +1,7 @@
+using Foxchat.Core;
+
+namespace Foxchat.Identity;
+
+public class InstanceConfig : CoreConfig
+{
+}

Foxchat.Identity/Migrations/20240512225835_Init.Designer.cs

@@ -0,0 +1,253 @@
+// <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 Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace Foxchat.Identity.Migrations
+{
+    [DbContext(typeof(IdentityContext))]
+    [Migration("20240512225835_Init")]
+    partial class Init
+    {
+        /// <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.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.HasKey("Id")
+                        .HasName("pk_tokens");
+
+                    b.HasIndex("AccountId")
+                        .HasDatabaseName("ix_tokens_account_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")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired()
+                        .HasConstraintName("fk_tokens_accounts_account_id");
+
+                    b.Navigation("Account");
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.Account", b =>
+                {
+                    b.Navigation("Tokens");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

Foxchat.Identity/Migrations/20240512225835_Init.cs

@@ -0,0 +1,181 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace Foxchat.Identity.Migrations
+{
+    /// <inheritdoc />
+    public partial class Init : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "accounts",
+                columns: table => new
+                {
+                    id = table.Column<Guid>(type: "uuid", nullable: false),
+                    username = table.Column<string>(type: "text", nullable: false),
+                    email = table.Column<string>(type: "text", nullable: false),
+                    password = table.Column<string>(type: "text", nullable: false),
+                    role = table.Column<int>(type: "integer", nullable: false),
+                    avatar = table.Column<string>(type: "text", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("pk_accounts", x => x.id);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "chat_instances",
+                columns: table => new
+                {
+                    id = table.Column<Guid>(type: "uuid", nullable: false),
+                    domain = table.Column<string>(type: "text", nullable: false),
+                    base_url = table.Column<string>(type: "text", nullable: false),
+                    public_key = table.Column<string>(type: "text", nullable: false),
+                    status = table.Column<int>(type: "integer", nullable: false),
+                    reason = table.Column<string>(type: "text", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("pk_chat_instances", x => x.id);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "instance",
+                columns: table => new
+                {
+                    id = table.Column<int>(type: "integer", nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
+                    public_key = table.Column<string>(type: "text", nullable: false),
+                    private_key = table.Column<string>(type: "text", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("pk_instance", x => x.id);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "tokens",
+                columns: table => new
+                {
+                    id = table.Column<Guid>(type: "uuid", nullable: false),
+                    account_id = table.Column<Guid>(type: "uuid", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("pk_tokens", x => x.id);
+                    table.ForeignKey(
+                        name: "fk_tokens_accounts_account_id",
+                        column: x => x.account_id,
+                        principalTable: "accounts",
+                        principalColumn: "id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "account_chat_instance",
+                columns: table => new
+                {
+                    accounts_id = table.Column<Guid>(type: "uuid", nullable: false),
+                    chat_instances_id = table.Column<Guid>(type: "uuid", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("pk_account_chat_instance", x => new { x.accounts_id, x.chat_instances_id });
+                    table.ForeignKey(
+                        name: "fk_account_chat_instance_accounts_accounts_id",
+                        column: x => x.accounts_id,
+                        principalTable: "accounts",
+                        principalColumn: "id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "fk_account_chat_instance_chat_instances_chat_instances_id",
+                        column: x => x.chat_instances_id,
+                        principalTable: "chat_instances",
+                        principalColumn: "id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "guild_accounts",
+                columns: table => new
+                {
+                    chat_instance_id = table.Column<Guid>(type: "uuid", nullable: false),
+                    guild_id = table.Column<string>(type: "text", nullable: false),
+                    account_id = table.Column<Guid>(type: "uuid", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("pk_guild_accounts", x => new { x.chat_instance_id, x.guild_id, x.account_id });
+                    table.ForeignKey(
+                        name: "fk_guild_accounts_accounts_account_id",
+                        column: x => x.account_id,
+                        principalTable: "accounts",
+                        principalColumn: "id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "fk_guild_accounts_chat_instances_chat_instance_id",
+                        column: x => x.chat_instance_id,
+                        principalTable: "chat_instances",
+                        principalColumn: "id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "ix_account_chat_instance_chat_instances_id",
+                table: "account_chat_instance",
+                column: "chat_instances_id");
+
+            migrationBuilder.CreateIndex(
+                name: "ix_accounts_email",
+                table: "accounts",
+                column: "email",
+                unique: true);
+
+            // EF Core doesn't support creating indexes on arbitrary expressions, so we have to create it manually.
+            migrationBuilder.Sql("CREATE UNIQUE INDEX ix_accounts_username ON accounts (lower(username))");
+
+            migrationBuilder.CreateIndex(
+                name: "ix_chat_instances_domain",
+                table: "chat_instances",
+                column: "domain",
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "ix_guild_accounts_account_id",
+                table: "guild_accounts",
+                column: "account_id");
+
+            migrationBuilder.CreateIndex(
+                name: "ix_tokens_account_id",
+                table: "tokens",
+                column: "account_id");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "account_chat_instance");
+
+            migrationBuilder.DropTable(
+                name: "guild_accounts");
+
+            migrationBuilder.DropTable(
+                name: "instance");
+
+            migrationBuilder.DropTable(
+                name: "tokens");
+
+            migrationBuilder.DropTable(
+                name: "chat_instances");
+
+            migrationBuilder.DropTable(
+                name: "accounts");
+        }
+    }
+}

Foxchat.Identity/Migrations/IdentityContextModelSnapshot.cs

@@ -0,0 +1,250 @@
+// <auto-generated />
+using System;
+using Foxchat.Identity.Database;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace Foxchat.Identity.Migrations
+{
+    [DbContext(typeof(IdentityContext))]
+    partial class IdentityContextModelSnapshot : ModelSnapshot
+    {
+        protected override void BuildModel(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.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.HasKey("Id")
+                        .HasName("pk_tokens");
+
+                    b.HasIndex("AccountId")
+                        .HasDatabaseName("ix_tokens_account_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")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired()
+                        .HasConstraintName("fk_tokens_accounts_account_id");
+
+                    b.Navigation("Account");
+                });
+
+            modelBuilder.Entity("Foxchat.Identity.Database.Models.Account", b =>
+                {
+                    b.Navigation("Tokens");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

Foxchat.Identity/Program.cs

@@ -0,0 +1,55 @@
+using Newtonsoft.Json.Serialization;
+using Serilog;
+using Foxchat.Core;
+using Foxchat.Identity;
+using Foxchat.Identity.Database;
+using Foxchat.Identity.Services;
+
+var builder = WebApplication.CreateBuilder(args);
+
+var config = builder.AddConfiguration<InstanceConfig>("identity.ini");
+
+builder.Services.AddSerilog(config.LogEventLevel);
+
+await BuildInfo.ReadBuildInfo();
+Log.Information("Starting Foxchat.Identity {Version} ({Hash})", BuildInfo.Version, BuildInfo.Hash);
+
+builder.Services
+    .AddControllers()
+    .AddNewtonsoftJson(options =>
+        options.SerializerSettings.ContractResolver = new DefaultContractResolver
+        {
+            NamingStrategy = new SnakeCaseNamingStrategy()
+        });
+
+builder.Services
+    .AddCoreServices<IdentityContext>()
+    .AddScoped<ChatInstanceResolverService>()
+    .AddEndpointsApiExplorer()
+    .AddSwaggerGen();
+
+var app = builder.Build();
+
+app.UseSerilogRequestLogging();
+app.UseRouting();
+app.UseSwagger();
+app.UseSwaggerUI();
+app.UseCors();
+app.UseAuthentication();
+app.UseAuthorization();
+app.MapControllers();
+
+using (var scope = app.Services.CreateScope())
+using (var context = scope.ServiceProvider.GetRequiredService<IdentityContext>())
+{
+    Log.Information("Initializing instance keypair...");
+    if (await context.InitializeInstanceAsync())
+    {
+        Log.Information("Initialized instance keypair");
+    }
+}
+
+app.Urls.Clear();
+app.Urls.Add(config.Address);
+
+app.Run();

Foxchat.Identity/Services/ChatInstanceResolverService.cs

@@ -0,0 +1,39 @@
+using Foxchat.Core.Federation;
+using Foxchat.Core.Models;
+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)
+{
+    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();
+        if (instance != null) return instance;
+
+        _logger.Information("Unknown chat instance {Domain}, fetching its data", domain);
+
+        var resp = await requestSigningService.RequestAsync<HelloResponse>(
+            HttpMethod.Post,
+            domain, "/_fox/chat/hello",
+            userId: null,
+            body: new HelloRequest(config.Domain)
+        );
+
+        instance = new ChatInstance
+        {
+            Domain = domain,
+            BaseUrl = $"https://{domain}",
+            PublicKey = resp.PublicKey,
+            Status = ChatInstance.InstanceStatus.Active,
+        };
+        await context.AddAsync(instance);
+        await context.SaveChangesAsync();
+
+        return instance;
+    }
+}

Foxchat.Identity/identity.ini

@@ -0,0 +1,15 @@
+Host = localhost
+Port = 7611
+Domain = id.fox.localhost
+
+; The level to log things at. Valid settings: Verbose, Debug, Information, Warning, Error, Fatal
+LogEventLevel = Debug
+
+[Database]
+; The database URL in ADO.NET format.
+Url = "Host=localhost;Database=foxchat_cs_ident;Username=foxchat;Password=password"
+
+; The timeout for opening new connections. Defaults to 5.
+Timeout = 5
+; The maximum number of open connections. Defaults to 50.
+MaxPoolSize = 500

Foxchat.sln

@@ -0,0 +1,28 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.0.31903.59
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Foxchat.Identity", "Foxchat.Identity\Foxchat.Identity.csproj", "{29265F09-5312-41B5-86C4-3B9EBF155F93}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Foxchat.Core", "Foxchat.Core\Foxchat.Core.csproj", "{06352B8B-628C-4476-9F78-83F326B05B16}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{29265F09-5312-41B5-86C4-3B9EBF155F93}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{29265F09-5312-41B5-86C4-3B9EBF155F93}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{29265F09-5312-41B5-86C4-3B9EBF155F93}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{29265F09-5312-41B5-86C4-3B9EBF155F93}.Release|Any CPU.Build.0 = Release|Any CPU
+		{06352B8B-628C-4476-9F78-83F326B05B16}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{06352B8B-628C-4476-9F78-83F326B05B16}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{06352B8B-628C-4476-9F78-83F326B05B16}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{06352B8B-628C-4476-9F78-83F326B05B16}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal

LICENSE

@@ -0,0 +1,201 @@
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build_info.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+(git rev-parse HEAD &&
+  git describe --tags --long &&
+  if test -z "$(git ls-files --exclude-standard --modified --deleted --others)"; then echo clean; else echo dirty; fi) > ../.version