[WIP] Analyze codebase for potential bugs and security vulnerabilities

[Copilot]

Security and Bug Fixes for epson-proxy

Phase 1: Analysis ✅

• Analyze codebase for security vulnerabilities
• Identify coding logic bugs
• Prioritize issues by severity

Phase 2: Critical Security Fixes

• Add request body size limit (DoS protection)
• Fix private key file permissions
• Add input validation for width/height (prevent division by zero)
• Add integer overflow checks
• Add proper error handling for integer parsing

Phase 3: High Priority Fixes

• Configure XML parser to prevent XXE attacks
• Add validation for image dimensions
• Add bounds checking for image slicing
• Handle partial writes in TCP/USB connections

Phase 4: Medium Priority Fixes

• Improve SSL certificate generation (random serial)
• Fix CORS whitelist logic
• Add context/timeout for infinite retry loop
• Add check for HTTP response write errors
• Document centering algorithm

Phase 5: Testing and Validation

• Run existing tests
• Request code review
• Run CodeQL security scan
• Verify all fixes

Original prompt

Analyze the codebase of the 'epson-proxy' repository for potential bugs and security vulnerabilities. Include potential issues in coding logic and security practices.

This pull request was created from Copilot chat.

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