API Validation & Error Handling Guide

Overview

This document describes the comprehensive validation and error handling system implemented for all API endpoints in the GXQ Studio platform.

Middleware Architecture

1. Validation Middleware (api/middleware/validation.ts)

Provides comprehensive input validation for all API endpoints.

Features:

• Type validation: string, number, boolean, array, object, email, url, solana-address
• Required field checking: Ensure mandatory fields are present
• Range validation: Min/max length for strings, min/max value for numbers
• Pattern matching: Regex validation for complex formats
• Enum validation: Restrict values to predefined set
• Custom validation: Custom validation functions
• Sanitization: Remove dangerous characters and HTML tags
• Rate limiting: In-memory rate limiting (use Redis in production)

Usage Example:

import { validateRequest, ValidationRule } from '../middleware/validation';

const rules: ValidationRule[] = [
  {
    field: 'username',
    type: 'string',
    required: true,
    min: 3,
    max: 50,
  },
  {
    field: 'walletAddress',
    type: 'solana-address',
    required: true,
  },
  {
    field: 'amount',
    type: 'number',
    required: true,
    min: 0,
    custom: (value) => value > 0 || 'Amount must be positive',
  },
];

// In your endpoint handler
const validation = validateRequest(req.body, rules);
if (!validation.valid) {
  return res.status(400).json({
    success: false,
    error: 'Validation failed',
    details: validation.errors,
  });
}

2. Error Handler Middleware (api/middleware/errorHandler.ts)

Provides centralized error handling with consistent error responses.

Error Types:

• ValidationError (400): Input validation failures
• AuthenticationError (401): Missing or invalid authentication
• AuthorizationError (403): Insufficient permissions
• NotFoundError (404): Resource not found
• RateLimitError (429): Rate limit exceeded
• ConfigurationError (500): Missing environment variables
• ExternalServiceError (503): External service failures

Usage Example:

import { withErrorHandler, ValidationError, checkRequiredEnv } from '../middleware/errorHandler';

export default withErrorHandler(async (req, res) => {
  // Check required environment variables
  checkRequiredEnv(['SOLANA_RPC_URL', 'WALLET_PRIVATE_KEY']);

  // Your endpoint logic
  if (!req.body.username) {
    throw new ValidationError('Username is required');
  }

  // Automatic error handling and consistent responses
  return res.status(200).json({ success: true, data: result });
});

3. CORS Middleware (api/middleware/cors.ts)

Handles Cross-Origin Resource Sharing for API endpoints.

Features:

• Origin validation: Whitelist allowed origins
• Credentials support: Enable/disable credentials
• Preflight handling: Automatic OPTIONS request handling
• Environment-aware: Different configs for dev/prod

Usage Example:

import { withCors, getCorsOptions } from '../middleware/cors';

export default withCors(async (req, res) => {
  // Your endpoint logic
  return res.status(200).json({ success: true });
}, getCorsOptions());

Endpoint Validation Standards

All Endpoints Must:

1. Validate Input

   • Check required fields
   • Validate data types
   • Sanitize user input
   • Validate Solana addresses

2. Handle Errors

   • Use consistent error format
   • Log errors with context
   • Return appropriate HTTP status codes
   • Never expose sensitive information

3. Implement Rate Limiting

   • Protect against abuse
   • Use appropriate limits per endpoint
   • Return 429 with reset time

4. Check Authentication (where required)

   • Verify JWT tokens
   • Check token expiration
   • Validate user permissions

5. Log Requests

   • Log important operations
   • Include request IDs
   • Log errors with full context

Error Response Format

All errors follow this standard format:

{
  "success": false,
  "error": "ERROR_CODE",
  "message": "Human-readable error message",
  "code": "ERROR_CODE",
  "details": {
    "field": "username",
    "reason": "Username must be at least 3 characters"
  },
  "timestamp": 1703001234567,
  "requestId": "req_abc123"
}

Validation Rules

Common Validation Patterns

Solana Address Validation

{
  field: 'walletAddress',
  type: 'solana-address',
  required: true,
}

Amount Validation

{
  field: 'amount',
  type: 'number',
  required: true,
  min: 0,
  custom: (value) => value <= 1000000 || 'Amount too large',
}

Command Validation

{
  field: 'command',
  type: 'string',
  required: true,
  enum: ['start', 'stop', 'pause', 'resume'],
}

Rate Limiting

Default Rate Limits

Endpoint	Limit	Window
/api/health	60 requests	1 minute
/api/admin/auth	5 requests	15 minutes
/api/monitor	10 requests	1 minute
/api/execute	5 requests	1 minute
/api/admin/*	30 requests	1 minute

Rate Limit Headers

X-RateLimit-Limit: 60
X-RateLimit-Remaining: 45
X-RateLimit-Reset: 1703001294567

Testing Endpoints

Automated Validation

Run the endpoint validation script:

npm run validate-endpoints http://localhost:3000

Manual Testing

Test Health Endpoint

curl http://localhost:3000/api/health

Test Auth Endpoint

curl -X POST http://localhost:3000/api/admin/auth \
  -H "Content-Type: application/json" \
  -d '{"username":"admin","password":"password"}'

Test Protected Endpoint

curl http://localhost:3000/api/admin/metrics \
  -H "Authorization: Bearer YOUR_JWT_TOKEN"

Security Best Practices

Input Validation

1. ✅ Always validate user input
2. ✅ Use type-safe validation
3. ✅ Sanitize HTML and scripts
4. ✅ Validate Solana addresses before use
5. ✅ Check array/object sizes

Error Handling

1. ✅ Never expose stack traces in production
2. ✅ Log errors with full context
3. ✅ Use appropriate HTTP status codes
4. ✅ Return generic error messages to users
5. ✅ Log sensitive operations

Authentication

1. ✅ Use JWT with expiration
2. ✅ Implement rate limiting on auth endpoints
3. ✅ Never log passwords or tokens
4. ✅ Use HTTPS in production
5. ✅ Rotate secrets regularly

Rate Limiting

1. ✅ Implement per-IP rate limiting
2. ✅ Use stricter limits for auth endpoints
3. ✅ Return clear error messages
4. ✅ Consider using Redis for distributed systems
5. ✅ Monitor for abuse patterns

Environment Configuration

Required Variables

# Required for all endpoints
SOLANA_RPC_URL=https://api.mainnet-beta.solana.com
WALLET_PRIVATE_KEY=your_base58_private_key

# Required for admin endpoints
ADMIN_USERNAME=admin
ADMIN_PASSWORD=strong_password
JWT_SECRET=your_32_character_secret

# Optional: Enhanced security
CRON_SECRET=your_cron_secret

Validation on Startup

import { checkRequiredEnv } from './middleware/errorHandler';

// Check at startup
checkRequiredEnv([
  'SOLANA_RPC_URL',
  'WALLET_PRIVATE_KEY',
  'ADMIN_USERNAME',
  'ADMIN_PASSWORD',
  'JWT_SECRET',
]);

Monitoring & Debugging

Request Logging

console.log(`[${new Date().toISOString()}] ${req.method} ${req.url}`);
console.log('Headers:', req.headers);
console.log('Body:', req.body);

Error Logging

import { logError } from './middleware/errorHandler';

logError(error, {
  endpoint: req.url,
  method: req.method,
  ip: getClientIp(req),
  userId: req.user?.id,
});

Health Monitoring

Monitor these metrics:

• Response times
• Error rates
• Rate limit hits
• Authentication failures
• RPC latency

Common Issues & Solutions

Issue: Validation Errors Not Showing

Solution: Ensure you're checking the details field in error responses.

Issue: CORS Errors in Browser

Solution: Check that your domain is in the allowed origins list.

Issue: Rate Limit Too Restrictive

Solution: Adjust rate limit parameters or implement user-based limits.

Issue: Slow Endpoint Responses

Solution:

1. Check RPC connection
2. Review database queries
3. Implement caching
4. Use connection pooling

Next Steps

1. ✅ Implement validation for all endpoints
2. ✅ Add comprehensive error handling
3. ✅ Set up rate limiting
4. ✅ Configure CORS properly
5. ✅ Test all endpoints
6. ✅ Monitor errors in production
7. ✅ Document API changes

Resources

• TypeScript Type Guards
• JWT Best Practices
• OWASP API Security
• Solana Web3.js Docs