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2026-06-29 07:36:04 +02:00
commit 5e5b875e37
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+using System.Text.Json;
+using FluentValidation;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+
+namespace Dotnet.Samples.AspNetCore.WebApi.Middlewares;
+
+/// <summary>
+/// Middleware for global exception handling with RFC 7807 Problem Details format.
+/// </summary>
+public class ExceptionMiddleware(
+    RequestDelegate next,
+    ILogger<ExceptionMiddleware> logger,
+    IHostEnvironment environment
+)
+{
+    private const string ProblemDetailsContentType = "application/problem+json";
+
+    private static readonly JsonSerializerOptions JsonOptions =
+        new() { PropertyNamingPolicy = JsonNamingPolicy.CamelCase };
+
+    /// <summary>
+    /// Invokes the middleware to handle exceptions globally.
+    /// </summary>
+    public async Task InvokeAsync(HttpContext context)
+    {
+        try
+        {
+            await next(context);
+        }
+        catch (Exception exception)
+        {
+            await HandleExceptionAsync(context, exception);
+        }
+    }
+
+    /// <summary>
+    /// Handles the exception and returns an RFC 7807 compliant error response.
+    /// </summary>
+    private async Task HandleExceptionAsync(HttpContext context, Exception exception)
+    {
+        var (status, title) = MapExceptionToStatusCode(exception);
+
+        var problemDetails = new ProblemDetails
+        {
+            Type = $"https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/{status}",
+            Title = title,
+            Status = status,
+            Detail = GetExceptionDetail(exception),
+            Instance = context.Request.Path
+        };
+
+        // Add trace ID for request correlation
+        problemDetails.Extensions["traceId"] = context.TraceIdentifier;
+
+        // codeql[cs/log-forging] Serilog structured logging automatically escapes control characters
+        logger.LogError(
+            exception,
+            "Unhandled exception occurred. TraceId: {TraceId}, Path: {Path}, StatusCode: {StatusCode}",
+            context.TraceIdentifier,
+            context.Request.Path,
+            status
+        );
+
+        // Only modify response if headers haven't been sent yet
+        if (!context.Response.HasStarted)
+        {
+            context.Response.StatusCode = status;
+            context.Response.ContentType = ProblemDetailsContentType;
+
+            await context.Response.WriteAsync(
+                JsonSerializer.Serialize(problemDetails, JsonOptions)
+            );
+        }
+        else
+        {
+            logger.LogWarning(
+                "Unable to write error response for TraceId: {TraceId}. Response has already started.",
+                context.TraceIdentifier
+            );
+        }
+    }
+
+    /// <summary>
+    /// Maps exception types to appropriate HTTP status codes and titles.
+    /// </summary>
+    private static (int StatusCode, string Title) MapExceptionToStatusCode(Exception exception)
+    {
+        return exception switch
+        {
+            ValidationException => (StatusCodes.Status422UnprocessableEntity, "Validation Error"),
+            ArgumentException
+            or ArgumentNullException
+                => (StatusCodes.Status400BadRequest, "Bad Request"),
+            InvalidOperationException => (StatusCodes.Status400BadRequest, "Invalid Operation"),
+            DbUpdateConcurrencyException => (StatusCodes.Status409Conflict, "Concurrency Conflict"),
+            OperationCanceledException => (StatusCodes.Status408RequestTimeout, "Request Timeout"),
+            _ => (StatusCodes.Status500InternalServerError, "Internal Server Error")
+        };
+    }
+
+    /// <summary>
+    /// Gets the exception detail based on the environment.
+    /// In Development: includes full exception details and stack trace.
+    /// In Production: returns a generic message without sensitive information.
+    /// </summary>
+    private string GetExceptionDetail(Exception exception)
+    {
+        if (environment.IsDevelopment())
+        {
+            return $"{exception.Message}\n\nStack Trace:\n{exception.StackTrace}";
+        }
+
+        return exception switch
+        {
+            ValidationException => exception.Message,
+            ArgumentException => exception.Message,
+            _ => "An unexpected error occurred while processing your request."
+        };
+    }
+}