Posts

Implementing Distributed Locking with Redis and IDistributedLock Distributed locking is a critical feature for ensuring resource safety in distributed applications. Here’s how you can implement a distributed lock using the IDistributedLock interface and Redis as the backing store, leveraging the StackExchange.Redis library. Step 1: Implement the IDistributedLock Interface Let’s start by creating the RedisDistributedLock class to implement the IDistributedLock interface: using StackExchange.Redis; using System; using System.Threading.Tasks; public class RedisDistributedLock : IDistributedLock { private readonly IDatabase _database; private readonly string _lockKey; private string _lockToken; public RedisDistributedLock(IDatabase database, string lockKey) { _database = database; _lockKey = lockKey; _lockToken = Guid.NewGuid().ToString(); } public async Task<bool> AcquireLockAsync(string resource, TimeSpan leaseTime) { _lockToken = Guid.NewGuid().ToString(); return await _database.StringSetAsync(resource, _lockToken, leaseTime, When.NotExists); } public async Task RenewLockAsync(TimeSpan leaseTime) { if (!await _database.StringGetAsync(_lockKey).ConfigureAwait(false).Equals(_lockToken)) { throw new InvalidOperationException("Cannot renew a lock that is not held."); } await _database.KeyExpireAsync(_lockKey, leaseTime); } public async Task ReleaseLockAsync() { var token = await _database.StringGetAsync(_lockKey); if (token == _lockToken) { await _database.KeyDeleteAsync(_lockKey); } } public void Dispose() { ReleaseLockAsync().GetAwaiter().GetResult(); } } Step 2: Create a Sample Console Application Next, build a console application to demonstrate the functionality of the RedisDistributedLock: ...

Installing and Configuring UFW on Debian: A Step-by-Step Guide Uncomplicated Firewall (UFW) is a user-friendly interface for managing iptables on Linux systems. This guide walks you through installing and configuring UFW on Debian to secure your server. 1. Update Package List Make sure your package index is up to date: sudo apt-get update 2. Install UFW Install the UFW package using: sudo apt-get install ufw 3. Check UFW Status Verify UFW’s current status: ...

Intel Core Ultra 7 155U vs AMD Ryzen 7 8840HS: A Performance Showdown Deciding between the Intel Core Ultra 7 155U and the AMD Ryzen 7 8840HS? Let’s break down their specs and performance to help you pick the right one for your needs. Intel Core Ultra 7 155U Cores and Threads: 12 cores, 14 threads Base Clock Speed: 1.70 GHz Max Turbo Frequency: 4.80 GHz Architecture: Meteor Lake Integrated Graphics: Intel Iris Xe 4 Core Graphics TDP: 15W Manufacturing Process: 7 nm AMD Ryzen 7 8840HS Cores and Threads: 8 cores, 16 threads Base Clock Speed: 3.30 GHz Max Turbo Frequency: 5.10 GHz Architecture: Zen 4 Integrated Graphics: AMD Radeon 780M TDP: 28W Manufacturing Process: 4 nm Performance Comparison Both processors pack a punch, but their strengths vary depending on the task. ...

Mastering Aspect-Oriented Programming (AOP): Concepts and Examples Aspect-Oriented Programming (AOP) is a programming paradigm that takes modularity to the next level. It allows you to neatly separate cross-cutting concerns like logging, security, or transaction management from your main business logic. Think of it as an enhancement to Object-Oriented Programming (OOP) that brings even more structure and reusability to your codebase. link to link to Key Concepts of AOP Here’s a quick dive into the foundational elements of AOP: ...

To create a code generator that automatically caches any function with a cache attribute that takes a duration, you can use a source generator in .NET. Source generators allow you to generate additional source code at compile time. Step 1: Define the Cache Attribute First, define the cache attribute that will be used to mark methods for caching: using System; [AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)] public sealed class CacheAttribute : Attribute { public CacheAttribute(int durationInSeconds) { DurationInSeconds = durationInSeconds; } public int DurationInSeconds { get; } } Step 2: Create the Source Generator Next, create the source generator that will generate the caching logic for methods marked with the CacheAttribute. ...

RedisDistributedLock Implementation in Aspect-Oriented Programming (AOP) Aspect-Oriented Programming (AOP) lends itself well to distributed resource management tasks such as locking. Below is an implementation of a Redis-based distributed lock using the StackExchange.Redis library, focusing on resource isolation and concurrency control. RedisDistributedLock Class Here is the complete implementation: using StackExchange.Redis; using System; using System.Threading.Tasks; public class RedisDistributedLock : IDisposable { private readonly IDatabase _redisDb; private readonly string _lockKey; private readonly string _lockValue; private bool _acquired; public RedisDistributedLock(IDatabase redisDb, string resourceKey) { _redisDb = redisDb; _lockKey = $"lock:{resourceKey}"; _lockValue = Guid.NewGuid().ToString(); // random token } /// <summary> /// Attempts to acquire a lock for the specified lock key with a given expiry. /// </summary> /// <param name="expiry">Duration for lock expiry.</param> /// <returns>True if the lock was acquired; otherwise, false.</returns> public async Task<bool> AcquireAsync(TimeSpan expiry) { _acquired = await _redisDb.StringSetAsync( key: _lockKey, value: _lockValue, expiry: expiry, when: When.NotExists); return _acquired; } /// <summary> /// Releases the lock if it’s still held by this instance. /// </summary> public async Task ReleaseAsync() { if (_acquired) { // Verify token before deleting. var currentValue = await _redisDb.StringGetAsync(_lockKey); if (currentValue == _lockValue) { await _redisDb.KeyDeleteAsync(_lockKey); } _acquired = false; } } /// <summary> /// Cleanup method ensuring the lock is freed. /// </summary> public void Dispose() { ReleaseAsync().GetAwaiter().GetResult(); } } Acquiring and Releasing the Lock Using the RedisDistributedLock class to acquire and release locks ensures concurrency control in distributed systems. ...

Mastering the Retry Pattern: Enhancing Application Resiliency The retry pattern is a crucial design technique for improving the resiliency of applications, especially when dealing with transient faults in external systems. Let’s explore its purpose, implementation, and how it contributes to robust architecture. Purpose of the Retry Pattern Automatic Retries: Enables applications to automatically retry a failed operation due to transient faults. Graceful Error Handling: Improves user experience by addressing errors seamlessly. Increased Reliability: Allows applications to recover from temporary issues, ensuring dependable performance. Key Concepts of the Retry Pattern Transient Faults: Temporary issues like network glitches, timeouts, or service throttling that are likely to succeed upon retry. Retry Interval: The delay between attempts, which can follow a fixed interval, exponential backoff, or a custom logic. Max Retry Attempts: Specifies the maximum number of retries before declaring the operation as failed. Implementation Example in C# Here’s how to implement a retry pattern using C#: ...

Message Envelopes in Message-Based Software Development In message-based software development, message envelopes are a design pattern used to wrap the core message with additional metadata. This metadata helps the messaging system process, route, or interpret the message without needing to understand its actual content. Key Features of Message Envelopes Header and Body Separation: The header contains metadata like routing information, encryption details, or timestamps. The body holds the actual message payload. Flexibility: ...

Performing CRUD Operations and Joining Tables with IOrganizationService When working with Microsoft Dataverse, IOrganizationService is a powerful API that enables direct interaction with the Dataverse environment. This guide demonstrates how to perform CRUD operations and retrieve related records using the OrganizationService in an ASP.NET Core application. Setup Before starting, ensure the required packages are installed: Install-Package Microsoft.CrmSdk.CoreAssemblies Install-Package Microsoft.CrmSdk.XrmTooling.CoreAssembly Connect to Dataverse Establish a connection to your Dataverse environment using a connection string: ...

Securing Your ASP.NET Core Web App: OWASP Top Ten Mitigations Building secure APIs and applications is crucial in today’s interconnected world. This post dives into the OWASP Top Ten vulnerabilities and how you can mitigate them in your ASP.NET Core Web API or application. 1. Injection (A01) Mitigation: Always use parameterized queries or ORM frameworks like Entity Framework. Explanation: Prevent untrusted data from being executed as code by treating it as data. Example: // BAD: vulnerable to SQL injection string sql = $"SELECT * FROM Users WHERE Name = '{userInput}'"; // GOOD: parameterized query string sql = "SELECT * FROM Users WHERE Name = @name"; command.Parameters.AddWithValue("@name", userInput); What can happen: An attacker could inject SQL to exfiltrate or delete sensitive data. 2. Broken Authentication (A02) Mitigation: Use ASP.NET Core Identity with robust password policies and MFA. Example: services.AddIdentity<ApplicationUser, IdentityRole>(options => { options.Password.RequiredLength = 8; options.Password.RequireNonAlphanumeric = true; }); What can happen: Attackers may gain unauthorized access and impersonate users. 3. Sensitive Data Exposure (A03) Mitigation: Use HTTPS and encrypt sensitive data at rest with ASP.NET Core Data Protection. Example: services.AddDataProtection().ProtectKeysWithDpapi(); app.UseHttpsRedirection(); What can happen: Sensitive information could be intercepted by attackers. 4. XML External Entities (XXE) (A04) Mitigation: Disable DTD processing in XML parsers. Example: var settings = new XmlReaderSettings { DtdProcessing = DtdProcessing.Prohibit }; What can happen: Attackers could exploit XXE to extract data or execute malicious actions. 5. Broken Access Control (A05) Mitigation: Use role-based access control. Example: [Authorize(Roles = "Admin")] public IActionResult AdminOnly() => View(); What can happen: Unauthorized users could access restricted resources. 6. Security Misconfiguration (A06) Mitigation: Use secure headers and disable unnecessary features. Example: services.AddHsts(options => { options.Preload = true; options.IncludeSubDomains = true; }); What can happen: Misconfigurations could lead to unauthorized access or system compromise. 7. Cross-Site Scripting (XSS) (A07) Mitigation: Sanitize user input with built-in libraries. Example: @Html.Encode(Model.UserInput) What can happen: Attackers could inject malicious scripts into your application. 8. Insecure Deserialization (A08) Mitigation: Avoid deserializing untrusted data. Example: var settings = new JsonSerializerSettings { TypeNameHandling = TypeNameHandling.None }; What can happen: Attackers may inject malicious payloads to execute arbitrary code. 9. Using Components with Known Vulnerabilities (A09) Mitigation: Regularly update dependencies and monitor vulnerabilities. Example: dotnet list package --outdated What can happen: Exploitable vulnerabilities in third-party components could compromise your application. 10. Insufficient Logging & Monitoring (A10) Mitigation: Implement robust logging and monitoring. Example: services.AddApplicationInsightsTelemetry(Configuration["InstrumentationKey"]); Log.Logger = new LoggerConfiguration().WriteTo.Console().CreateLogger(); What can happen: Without logs, attacks may go unnoticed, leading to prolonged damage. Conclusion By following these mitigation strategies, you can significantly improve the security posture of your ASP.NET Core Web API. For more resources, check out the OWASP DotNet Security Cheat Sheet. ...