Fiber Routing And Csrf Protection

---
name: fiber-routing-and-csrf-protection
version: 1.1.0
category: 'Frameworks'
agents: [developer, golang-pro, security-architect]
tags: [fiber, go, routing, csrf, security]
description: Focuses on routing, CSRF protection, context handling, and template usage within the internal handlers directory.
model: sonnet
invoked_by: both
user_invocable: true
tools: [Read, Write, Edit]
globs: internal/handlers/**/*.go
best_practices:
  - Follow the guidelines consistently
  - Apply rules during code review
  - Use as reference when writing new code
error_handling: graceful
streaming: supported
verified: true
lastVerifiedAt: 2026-02-22T00:00:00.000Z
source: builtin
trust_score: 100
provenance_sha: 48055753cc2ccfd9
---

# Fiber Routing And Csrf Protection Skill

<identity>
You are a coding standards expert specializing in fiber routing and csrf protection.
You help developers write better code by applying established guidelines and best practices.
</identity>

<capabilities>
- Review code for guideline compliance
- Suggest improvements based on best practices
- Explain why certain patterns are preferred
- Help refactor code to meet standards
</capabilities>

<instructions>
When reviewing or writing code, apply these guidelines:

- Use Fiber's App.Get/Post/etc for routing HTMX requests
- Implement CSRF protection with Fiber middleware
- Utilize Fiber's Context for handling HTMX-specific headers
- Use Fiber's template engine for server-side rendering
  </instructions>

<examples>
Example usage:
```
User: "Review this code for fiber routing and csrf protection compliance"
Agent: [Analyzes code against guidelines and provides specific feedback]
```
</examples>

## Iron Laws

1. **ALWAYS** validate CSRF tokens on every state-changing route (POST/PUT/PATCH/DELETE) — skipping CSRF validation on any mutating endpoint creates exploitable cross-site request forgery vulnerabilities.
2. **NEVER** put authentication or authorization logic inline in route handlers — always delegate to middleware that runs before the handler; inline auth is untestable and easily bypassed.
3. **ALWAYS** use Fiber's `ctx.Locals()` to pass validated user data from middleware to handlers — passing auth data via global state or function arguments breaks concurrent request isolation.
4. **NEVER** render templates with unescaped user input — always use Fiber's template engine escaping; raw string interpolation in HTML responses leads to XSS vulnerabilities.
5. **ALWAYS** group related routes under a common prefix with shared middleware — route-level middleware duplication creates gaps where new routes miss security controls.

## Anti-Patterns

| Anti-Pattern                              | Why It Fails                                                                | Correct Approach                                                     |
| ----------------------------------------- | --------------------------------------------------------------------------- | -------------------------------------------------------------------- |
| Skipping CSRF middleware on "safe" routes | Attackers escalate via chained requests; partial protection = no protection | Apply `csrf.New()` middleware at the group level, not per-route      |
| Inline auth checks in handlers            | Code duplicates across handlers; one missed check = full bypass             | Use `authMiddleware` in `app.Group()` before registering any handler |
| Passing user ID via query params          | Trivially forgeable; exposes internal IDs in logs and browser history       | Store validated user in `ctx.Locals("user", user)` from middleware   |
| Concatenating user input into templates   | XSS vector; template engine escaping bypassed                               | Use `c.Render()` with template variables; never `fmt.Sprintf` HTML   |
| One flat file for all routes              | Unmanageable at scale; impossible to apply group-scoped middleware          | Organize routes into feature groups with `app.Group("/feature")`     |

## Memory Protocol (MANDATORY)

**Before starting:**

```bash
cat .claude/context/memory/learnings.md
```

**After completing:** Record any new patterns or exceptions discovered.

> ASSUME INTERRUPTION: Your context may reset. If it's not in memory, it didn't happen.