Noxious server consists of a core crate, and a server crate.
The core crate contains the serializable data types, as well as the proxy runner, toxics and some state management. The server crate contains the REST API server and the Store which manages proxy and toxic CRUD operations.
The client library uses the types from core offers an async client to the Toxiproxy API interface.
For every client connection, an upstream and a downstream Link are created. Each link owns a read and write handle, as well as the toxics for its direction. When a link is established, the read and write handles are connected via toxics.
In Noxious, most toxics simply take an input Stream of Bytes, and write data to a Sink of Bytes. Data passes through a chain of toxics and each toxic can manipulate the data passed, i.e. add delay, split packets into smaller packets etc. Some toxics like SlowClose and LimitData need more information about the connection, so they also take a Stop signal.
Noxious has a few key differences from Toxiproxy in how it adds and executes toxics on proxy connections:
- It does not insert a
Nooptoxic as the first toxic in the chain. - When the toxics are updated for a proxy, it re-creates links with new toxic chains instead of mutating the existing toxic chain, without closing the proxy connection.
- When a proxy is updated, it drops the old proxy, causing old connection to disconnect. This is practically the same behavior as Toxicproxy, as if you update the listen address or upstream address, you must close the proxy connections.