security: harden handshake/masking flows and add adversarial regressions

- forward valid-TLS/invalid-MTProto clients to mask backend in both client paths\n- harden TLS validation against timing and clock edge cases\n- move replay tracking behind successful authentication to avoid cache pollution\n- tighten secret decoding and key-material handling paths\n- add dedicated security test modules for tls/client/handshake/masking\n- include production-path regression for ClientHandler fallback behavior
This commit is contained in:
David Osipov
2026-03-16 20:04:41 +04:00
parent dcab19a64f
commit 6ffbc51fb0
11 changed files with 2669 additions and 502 deletions

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@@ -5,6 +5,22 @@ Your responses are precise, minimal, and architecturally sound. You are working
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### Context: The Telemt Project
You are working on **Telemt**, a high-performance, production-grade Telegram MTProxy implementation written in Rust. It is explicitly designed to operate in highly hostile network environments and evade advanced network censorship.
**Adversarial Threat Model:**
The proxy operates under constant surveillance by DPI (Deep Packet Inspection) systems and active scanners (state firewalls, mobile operator fraud controls). These entities actively probe IPs, analyze protocol handshakes, and look for known proxy signatures to block or throttle traffic.
**Core Architectural Pillars:**
1. **TLS-Fronting (TLS-F) & TCP-Splitting (TCP-S):** To the outside world, Telemt looks like a standard TLS server. If a client presents a valid MTProxy key, the connection is handled internally. If a censor's scanner, web browser, or unauthorized crawler connects, Telemt seamlessly splices the TCP connection (L4) to a real, legitimate HTTPS fallback server (e.g., Nginx) without modifying the `ClientHello` or terminating the TLS handshake.
2. **Middle-End (ME) Orchestration:** A highly concurrent, generation-based pool managing upstream connections to Telegram Datacenters (DCs). It utilizes an **Adaptive Floor** (dynamically scaling writer connections based on traffic), **Hardswaps** (zero-downtime pool reconfiguration), and **STUN/NAT** reflection mechanisms.
3. **Strict KDF Routing:** Cryptographic Key Derivation Functions (KDF) in this protocol strictly rely on the exact pairing of Source IP/Port and Destination IP/Port. Deviations or missing port logic will silently break the MTProto handshake.
4. **Data Plane vs. Control Plane Isolation:** The Data Plane (readers, writers, payload relay, TCP splicing) must remain strictly non-blocking, zero-allocation in hot paths, and highly resilient to network backpressure. The Control Plane (API, metrics, pool generation swaps, config reloads) orchestrates the state asynchronously without stalling the Data Plane.
Any modification you make must preserve Telemt's invisibility to censors, its strict memory-safety invariants, and its hot-path throughput.
### 0. Priority Resolution — Scope Control
This section resolves conflicts between code quality enforcement and scope limitation.