# rs-soroban-env > **Warning**: this fork of the soroban host environment is not SDF-maintained, hasn't been audited, doesn't enforce correct resources metering and should not be used to execute contracts in a Soroban production environment. This is a fork that enables Soroban to be hardwired into [Zephyr](https://mercurydata.app/zephyr-vm). Rust contract-environment interface and (optional) host implementation for Soroban. The `soroban-env-common` crate contains elements of the shared environment-interface between smart contract guest and host: the `Env` trait that defines the set of available environment functions as well as the `Val` type that can pass back and forth through the WASM calling convention. Additionally small wrappers around subtypes of `Val` are included: `Object`, `Symbol`, `Error`, etc. The `soroban-env-guest` crate contains the guest-side _stub implementation_ of the environment interface called `Guest` dependent on extern fns provided by the host implementation. This can be used in a WASM runtime that provides the extern fns. The `soroban-env-host` crate contains the host-side _full implementation_ of the environment interface called `Host`. This can be used either in the real blockchain host, or for local testing in the SDK.