add a bunch of stuff copied from Foxchat.NET

Foxnouns.Backend/Middleware/AuthenticationMiddleware.cs

@@ -0,0 +1,66 @@
+using System.Security.Cryptography;
+using Foxnouns.Backend.Database;
+using Foxnouns.Backend.Database.Models;
+using Foxnouns.Backend.Utils;
+using Microsoft.EntityFrameworkCore;
+using NodaTime;
+
+namespace Foxnouns.Backend.Middleware;
+
+public class AuthenticationMiddleware(DatabaseContext db, IClock clock) : IMiddleware
+{
+    public async Task InvokeAsync(HttpContext ctx, RequestDelegate next)
+    {
+        var endpoint = ctx.GetEndpoint();
+        var metadata = endpoint?.Metadata.GetMetadata<AuthenticateAttribute>();
+
+        if (metadata == null)
+        {
+            await next(ctx);
+            return;
+        }
+
+        var header = ctx.Request.Headers.Authorization.ToString();
+        if (!OauthUtils.TryFromBase64String(header, out var rawToken))
+        {
+            await next(ctx);
+            return;
+        }
+
+        var hash = SHA512.HashData(rawToken);
+        var oauthToken = await db.Tokens
+            .Include(t => t.Application)
+            .Include(t => t.User)
+            .FirstOrDefaultAsync(t => t.Hash == hash && t.ExpiresAt > clock.GetCurrentInstant() && !t.ManuallyExpired);
+        if (oauthToken == null)
+        {
+            await next(ctx);
+            return;
+        }
+
+        ctx.SetToken(oauthToken);
+
+        await next(ctx);
+    }
+}
+
+public static class HttpContextExtensions
+{
+    private const string Key = "token";
+
+    public static void SetToken(this HttpContext ctx, Token token) => ctx.Items.Add(Key, token);
+    public static User? GetUser(this HttpContext ctx) => ctx.GetToken()?.User;
+
+    public static User GetUserOrThrow(this HttpContext ctx) =>
+        ctx.GetUser() ?? throw new ApiError.AuthenticationError("No user in HttpContext");
+
+    public static Token? GetToken(this HttpContext ctx)
+    {
+        if (ctx.Items.TryGetValue(Key, out var token))
+            return token as Token;
+        return null;
+    }
+}
+
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
+public class AuthenticateAttribute : Attribute;

Foxnouns.Backend/Middleware/AuthorizationMiddleware.cs

@@ -0,0 +1,36 @@
+using Foxnouns.Backend.Utils;
+
+namespace Foxnouns.Backend.Middleware;
+
+public class AuthorizationMiddleware : IMiddleware
+{
+    public async Task InvokeAsync(HttpContext ctx, RequestDelegate next)
+    {
+        var endpoint = ctx.GetEndpoint();
+        var attribute = endpoint?.Metadata.GetMetadata<AuthorizeAttribute>();
+
+        if (attribute == null)
+        {
+            await next(ctx);
+            return;
+        }
+
+        var token = ctx.GetToken();
+        if (token == null)
+            throw new ApiError.Unauthorized("This endpoint requires an authenticated user.");
+        if (attribute.Scopes.Length > 0 && attribute.Scopes.Except(token.Scopes.ExpandScopes()).Any())
+            throw new ApiError.Forbidden("This endpoint requires ungranted scopes.",
+                attribute.Scopes.Except(token.Scopes.ExpandScopes()));
+
+        await next(ctx);
+    }
+}
+
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
+public class AuthorizeAttribute(params string[] scopes) : Attribute
+{
+    public readonly bool RequireAdmin = scopes.Contains(":admin");
+    public readonly bool RequireModerator = scopes.Contains(":moderator");
+
+    public readonly string[] Scopes = scopes.Except([":admin", ":moderator"]).ToArray();
+}

Foxnouns.Backend/Middleware/ErrorHandlerMiddleware.cs

@@ -0,0 +1,93 @@
+using System.Net;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Converters;
+
+namespace Foxnouns.Backend.Middleware;
+
+public class ErrorHandlerMiddleware(ILogger baseLogger) : IMiddleware
+{
+    public async Task InvokeAsync(HttpContext ctx, RequestDelegate next)
+    {
+        try
+        {
+            await next(ctx);
+        }
+        catch (Exception e)
+        {
+            var type = e.TargetSite?.DeclaringType ?? typeof(ErrorHandlerMiddleware);
+            var typeName = e.TargetSite?.DeclaringType?.FullName ?? "<unknown>";
+            var logger = baseLogger.ForContext(type);
+
+            if (ctx.Response.HasStarted)
+            {
+                logger.Error(e, "Error in {ClassName} ({Path}) after response started being sent", typeName,
+                    ctx.Request.Path);
+                return;
+            }
+
+            if (e is ApiError ae)
+            {
+                ctx.Response.StatusCode = (int)ae.StatusCode;
+                ctx.Response.Headers.RequestId = ctx.TraceIdentifier;
+                ctx.Response.ContentType = "application/json; charset=utf-8";
+                if (ae is ApiError.Forbidden fe)
+                {
+                    await ctx.Response.WriteAsync(JsonConvert.SerializeObject(new HttpApiError
+                    {
+                        Status = (int)fe.StatusCode,
+                        Code = ErrorCode.Forbidden,
+                        Message = fe.Message,
+                        Scopes = fe.Scopes.Length > 0 ? fe.Scopes : null
+                    }));
+                    return;
+                }
+
+                await ctx.Response.WriteAsync(JsonConvert.SerializeObject(new HttpApiError
+                {
+                    Status = (int)ae.StatusCode,
+                    Code = ErrorCode.GenericApiError,
+                    Message = ae.Message,
+                }));
+                return;
+            }
+
+            if (e is FoxnounsError fce)
+            {
+                logger.Error(fce.Inner ?? fce, "Exception in {ClassName} ({Path})", typeName, ctx.Request.Path);
+            }
+            else
+            {
+                logger.Error(e, "Exception in {ClassName} ({Path})", typeName, ctx.Request.Path);
+            }
+
+            ctx.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
+            ctx.Response.Headers.RequestId = ctx.TraceIdentifier;
+            ctx.Response.ContentType = "application/json; charset=utf-8";
+            await ctx.Response.WriteAsync(JsonConvert.SerializeObject(new HttpApiError
+            {
+                Status = (int)HttpStatusCode.InternalServerError,
+                Code = ErrorCode.InternalServerError,
+                Message = "Internal server error",
+            }));
+        }
+    }
+}
+
+public record HttpApiError
+{
+    public required int Status { get; init; }
+    [JsonConverter(typeof(StringEnumConverter))]
+    public required ErrorCode Code { get; init; }
+    public required string Message { get; init; }
+    [JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
+    public string[]? Scopes { get; init; }
+}
+
+public enum ErrorCode
+{
+    InternalServerError,
+    Forbidden,
+    BadRequest,
+    AuthenticationError,
+    GenericApiError,
+}