# Rutster

A memory-safe, API-first, security-first telephony platform — a spiritual successor
to Asterisk for the WebRTC/microservices era, written in Rust.

> Not a port of Asterisk. A reimagining that keeps the *power* — era-bridging breadth,
> "wire anything to anything," a deep feature library — while dropping the legacy
> hardware/dead-protocol half and fixing Asterisk's two chronic wounds:
> memory-safety CVEs and toll fraud, at the design level.

## What it is / isn't

- **Is:** SIP (TLS-only) + WebRTC signaling, a real-time media plane (transcode / mix /
  DSP), a programmable call model exposed as a REST/gRPC API + event stream, a
  WASM-sandboxed plugin runtime, and a library of telephony features delivered as
  isolated services.
- **Isn't:** A TDM/PSTN-hardware PBX. No DAHDI, no Sangoma/Digium cards, no ISDN/SS7,
  no IAX2/H.323/SCCP/MGCP/Unistim. PSTN reach is via SIP trunks / SBC only.

## Core design pillars

1. **Memory-safe by construction** — Rust everywhere on the hot path; fuzzed, sans-IO
   protocol parsers. Eliminates the buffer-overflow/RCE CVE class.
2. **Isolation over in-process modules** — extensions run in a **WASM sandbox**, not as
   `.so` files in the daemon's address space. One bad plugin can't crash the box or
   read another tenant's media. (The Asterisk `core show locks` era ends here.)
3. **Secure & deny-by-default** — mandatory TLS/SRTP, deny-by-default routing,
   built-in toll-fraud controls, mTLS gRPC admin (no plaintext AMI), hard multi-tenancy.
4. **Three planes, scaled independently** — control / media / app. The media datapath
   stays tight; business logic is microservices and plugins around it.
5. **Observable & declarative** — OpenTelemetry call traces across services;
   config-as-data, not imperative `.conf` files edited on a box.

## Layout

- [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) — the three-plane model and pillars.
- [`docs/PORT_PLAN.md`](docs/PORT_PLAN.md) — **the spine**: every Asterisk subsystem mapped
  to a disposition (core / plugin / service / edge-FFI / dropped) with rationale.

## Status

Scoping. No code yet — the port plan defines the crate/service boundaries that the
workspace will be scaffolded from next.

## Open decisions

- **License** — undecided (Asterisk is GPLv2+commercial; rutster's model is TBD).
- **SIP stack** — FFI to pjproject vs. front with an SBC (Kamailio/drachtio) vs. a
  long-term pure-Rust stack. See port plan §1.
- **WASM runtime** — `wasmtime` is the presumptive default (component model).