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MTProto Proxy Zig Gotchas

Testing & Quality
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Practical Zig/runtime pitfalls and invariants for this codebase after epoll rewrite.

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Zig Gotchas (Current)

This is the short list of things that matter in this repository now.

1) Do not re-introduce thread-per-connection behavior

  • The proxy core is event-loop based.
  • Any reintroduction of per-connection threads/stacks will explode memory under high connection counts.

2) Keep I/O path non-blocking

  • Socket reads/writes/connect must remain non-blocking in runtime path.
  • If adding new protocol phases, model them as explicit state transitions.

3) Keep handshake checks strict

  • TLS-auth validation is not enough by itself.
  • SNI must match configured tls_domain in runtime path.

4) Replay protection keying

  • Replay cache should key on canonical HMAC output, not mutable wire representation.
  • This avoids shape-based bypasses on timestamp-masked bytes.

5) Avoid hidden O(N) queue drains in hot path

  • For message queues, avoid repeated front-removal copies.
  • Use head index/ring style progression and periodic compaction.

6) Allocation policy

  • Keep large per-connection buffers on-demand.
  • Idle connections should hold minimal state.

7) Logging policy

  • Keep hot path logs minimal.
  • Avoid debug-level flood in production traffic path.

8) Security fetch policy

  • No insecure TLS fallback for Telegram metadata fetches.
  • If refresh fails, keep last known-good state and warn.

9) Linux assumptions

  • Runtime behavior is Linux-specific (epoll, socket options, /proc-style benchmarking assumptions).

10) Keep docs and probe modes in sync

  • If probe traffic modes or semantics change, update:
    • test/README.md
    • main README.md benchmark references