Attaching Rocket fairings
In real life, a rocket fairing is a nose cone used to protect the rocket payload. In the Rocket framework, a fairing is not used to protect the payload but is instead used to hook in to any part of the request life cycle and rewrite the payload. Fairings are analogous to middleware in other web frameworks but with few differences.
Other framework middleware may be able to inject any arbitrary data. In Rocket, the fairing can be used to modify the request but cannot be used to add information that is not part of the request. For example, we can use fairings to add a new HTTP header in the requests or responses.
Some web frameworks might be able to terminate and directly respond to incoming requests, but in Rocket, the fairings cannot stop the incoming requests directly; the request must go through the route handling function, and then the route can create the proper response.
We can create a fairing by implementing rocket::fairing::Fairing for a type...