Code review: terminal TLS MITM proxy in Rust (ratatui, tokio, rcgen, rustls)

code review
1

I've been building Cogitator, a terminal-based TLS MITM intercepting
proxy in Rust, primarily as a learning project for both network security
and the language itself. Would appreciate any feedback on architecture
and Rust-specific decisions.

Core stack:

  • tokio 1 (full) — async runtime for the proxy core
  • ratatui 0.26 + crossterm — TUI with 6 screens
  • rcgen 0.13 — on-the-fly per-domain leaf certificate signing
  • rustls 0.23 + tokio-rustls 0.26 + webpki-roots — TLS stack
  • hyper 1.0 + hyper-util + http-body-util — HTTP layer
  • reqwest 0.12 — outbound requests (brotli/gzip/deflate)
  • libloading + inventory — external .so plugin system
  • tracing + tracing-subscriber (json) — structured logging
  • hickory-client — DNS queries

Decisions I'm unsure about and would love feedback on:

  • Coexisting the async proxy core with the synchronous ratatui event
    loop via block_in_place / spawn_blocking — is there a cleaner
    pattern for this?
  • Per-domain TlsAcceptor cache behind Arc<Mutex<HashMap>> —
    worth switching to DashMap?
  • Using hyper 1.0 directly alongside reqwest 0.12 (which uses
    hyper internally) — is there redundancy here worth cleaning up?
  • SiteAnalyzer trait for DI in the proxy pipeline — does this feel
    idiomatic or over-engineered for this scale?

What it does:

  • TLS MITM with ALPN/HTTP2, WebSocket interception (RFC 6455)
  • Frozen mode — pause live requests, edit headers/body, forward/drop
  • Active scanner: SQLi (error-based), XSS (reflected/stored),
    Path Traversal
  • Repeater, Intruder (Sniper/BatteringRam/Pitchfork/ClusterBomb),
    BFS Spider
  • Plugin system with versioned ABI via cogitator-plugin-api crate

GitHub: GitHub - LeechoShoop/cogitator: Terminal TLS MITM intercepting proxy and web security toolkit written in Rust · GitHub

2

I'll be honest, I don't know what those acronyms mean and I can't comment on the stack. I'd done a lot of work on mitm proxies a while back and the biggest feature gap between MITM Proxy (in Python) and building in Rust is the scripting.

It's a problem that the Proxelar crate ran into and decided to solve by bringing in Lua scripts. So my advice would be to build the well-covered territory until you get to that point, then decide what you want to do about scripting. Have fun!

3

Thanks for taking a look at my project, seantiz! It's more of a
research exploration into what Rust can do for this kind of tooling
than a finished product.

Scripting and plugins are actually already on my roadmap — Cogitator
has a plugin system via a separate cogitator-plugin-api crate with
a versioned ABI and dynamic .so loading. Not as frictionless as
Python scripts yet, but the foundation is there.

The Lua idea is interesting — a much lighter path for quick request
manipulation without writing a full Rust plugin. I'll definitely keep
it in mind for a future release. Appreciate the insight!