feat: Implement initial TLS termination and dynamic port handling (with compilation errors)

PLAN.md

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+## Plan for TLS Termination and Dynamic Port Handling
+
+### Task
+Modify the `l4p` (layer 4 proxy) to perform TLS termination and handle dynamic/random ports for backend services. The backend services are on a specific IPv6 address, and the user can dynamically determine the hostname of these services in the format "https://{port}.my-host". The proxy should listen on port 443 and use SNI for routing.
+
+### Completed Actions
+
+- Added `tokio-rustls`, `rustls-pemfile`, `anyhow` dependencies to `Cargo.toml`.
+- Modified `src/config/config_v1.rs` to include `TlsTerminationConfig`, `CertificateConfig`, `SniCertificateConfig` structs and updated `ServerConfig`.
+- Created `src/tls.rs` (multiple iterations due to compilation issues).
+- Integrated `anyhow::Result` into various functions and imported `Context` to `src/servers/mod.rs`.
+- Corrected imports in `src/main.rs`, `src/servers/mod.rs`, `src/servers/protocol/tcp.rs`.
+- Removed `mod tls;` from `src/servers/protocol/mod.rs`.
+- Attempted to fix various compilation errors related to `rustls` API changes, lifetime issues, and `tokio` task handling.
+- Changed `handle.await??;` to explicit match for debugging purposes.
+
+### Current State (with persistent errors)
+
+The code currently has compilation errors, primarily related to:
+
+1.  **`src/servers/mod.rs`**: Still showing an error for `map_err` not found for unit type `()`. This arises from the complex double `Result` handling (`Result<anyhow::Result<()>, JoinError>`) when awaiting spawned tasks.
+2.  **`src/tls.rs`**: Facing issues with `rustls::pki_types::PrivateKeyDer` and `CertificateDer` conversions, specifically for ensuring `'static` lifetimes and incorrect method usages like `to_vec()` or `as_ref()`, or `into_owned()` methods not existing for certain types. The `borrowed data escapes outside of function` error indicates deeper lifetime mismatches.
+
+### Next Steps (Requires Manual Intervention)
+
+- **Refactor `src/servers/mod.rs` error handling**: The current `match handle.await` block needs to be carefully reviewed to ensure correct unwraping of the nested `Result` types and proper error propagation from `tokio::task::JoinError` to `anyhow::Error`.
+- **Re-evaluate `src/tls.rs` `rustls::pki_types` usage**: A deeper understanding of `rustls-pki-types` crate and its `CertificateDer` and `PrivateKeyDer` lifetimes and conversion methods is needed. The specific error message `no method named to_vec found for struct PrivatePkcs8KeyDer` is a key indicator of incorrect usage.
+- **Review `rustls` version and documentation**: It might be helpful to review the `rustls` and `tokio-rustls` documentation for version-specific changes and best practices regarding `pki_types` and asynchronous error handling.
+
+This commit contains the work in progress as of the current session, including these unresolved errors, to allow for external review and debugging.