first commit

2026-06-13 23:23:50 +03:00
commit 23958e8e2c
72 changed files with 6142 additions and 0 deletions
@@ -0,0 +1,109 @@
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Options;
+
+namespace SequenceAuth.Lib;
+
+public class SequenceAuthMiddleware(RequestDelegate next, IOptions<SequenceAuthOptions> options)
+{
+    private readonly SequenceAuthOptions _options = options?.Value ?? throw new InvalidOperationException("SequenceAuthOptions must be registered in DI using AddSequenceAuth.");
+
+    public async Task InvokeAsync(HttpContext context, SequenceManager sequenceManager)
+    {
+        await (context.Request.Method switch
+        {
+            "OPTIONS" => next(context),
+            _ => ProcessPath(context, sequenceManager)
+        });
+    }
+
+    private async Task ProcessPath(HttpContext context, SequenceManager sequenceManager)
+    {
+        var path = context.Request.Path.Value?.ToLowerInvariant() ?? "";
+        
+        var isIgnored = _options.IgnoredPaths.FirstOrDefault(x => path.StartsWith(x));
+        await (isIgnored switch
+        {
+            null => CheckHeader(context, sequenceManager),
+            _ => next(context)
+        });
+    }
+
+    private async Task CheckHeader(HttpContext context, SequenceManager sequenceManager)
+    {
+        var headerCount = context.Request.Headers[_options.AuthHeaderName].Count;
+        
+        await (headerCount switch
+        {
+            0 => HandleMissingHeader(context),
+            > 0 => ProcessWithHeader(context, sequenceManager, context.Request.Headers[_options.AuthHeaderName].ToString()!),
+            _ => HandleMissingHeader(context)
+        });
+    }
+
+    private Task HandleMissingHeader(HttpContext context)
+    {
+        context.Response.StatusCode = 401;
+        return Task.CompletedTask;
+    }
+    
+    private async Task ProcessWithHeader(HttpContext context, SequenceManager sequenceManager, string sequenceId)
+    {
+        var result = await sequenceManager.ValidateAndRotateAsync(sequenceId);
+        
+        await (result.Outcome switch
+        {
+            ValidationOutcome.Success => HandleSuccess(context, result.NextSequence, result.UserId, result.RequestsRemaining),
+            _ => HandleFailure(context, result.Outcome)
+        });
+    }
+    
+    private async Task HandleSuccess(HttpContext context, Option<string> nextSequenceOpt, Option<string> userIdOpt, Option<int> requestsRemainingOpt)
+    {
+        _ = nextSequenceOpt.State switch
+        {
+            OptionState.Some => AddHeader(context, nextSequenceOpt.Value!),
+            OptionState.None => 0,
+            _ => 0
+        };
+
+        _ = userIdOpt.State switch
+        {
+            OptionState.Some => AddUserContext(context, userIdOpt.Value!),
+            OptionState.None => 0,
+            _ => 0
+        };
+        
+        _ = requestsRemainingOpt.State switch
+        {
+            OptionState.Some => AddRemainingHeader(context, requestsRemainingOpt.Value),
+            OptionState.None => 0,
+            _ => 0
+        };
+        
+        await next(context);
+    }
+    
+    private int AddRemainingHeader(HttpContext context, int remaining)
+    {
+        context.Response.Headers.Append(_options.RequestsRemainingHeaderName, remaining.ToString());
+        return 1;
+    }
+    
+    private int AddHeader(HttpContext context, string value)
+    {
+        context.Response.Headers.Append(_options.NextHeaderName, value);
+        return 1;
+    }
+    
+    private int AddUserContext(HttpContext context, string userId)
+    {
+        context.Items[_options.UserIdItemKey] = userId;
+        return 1;
+    }
+    
+    private Task HandleFailure(HttpContext context, ValidationOutcome outcome)
+    {
+        context.Response.StatusCode = 401;
+        return Task.CompletedTask;
+    }
+}