Trait EnvelopePolicy 

pub trait EnvelopePolicy:
    Send
    + Sync
    + 'static {
    // Required method
    fn mode(&self, request: &PolicyRequest<'_>) -> EnvelopeMode;

    // Provided method
    fn unresolved_mode(&self) -> EnvelopeMode { ... }
}

Picks the EnvelopeMode for a request, from the op it addresses.

EnvelopeMode implements it (one mode for every op), and so does any Fn(&PolicyRequest<'_>) -> EnvelopeMode, so a per-op policy is a closure:

use cratestack_axum::envelope_layer::{EnvelopeMode, PolicyRequest};

let policy = |request: &PolicyRequest<'_>| {
    if request.is_subscription() { EnvelopeMode::Optional } else { EnvelopeMode::Required }
};

There is no default: the layer’s builder refuses to build without one (decision D9). A policy sees no header (PolicyRequest), so no request can talk it into a weaker mode.

What the layer enforces whatever this returns: a request with a COSE body is opened (or, under Off, refused) regardless; under Required no unsigned request reaches the router and no response leaves unsealed; a /rpc/batch call runs under the strictest mode of batch and every frame’s op (decision B1). A policy can only choose how strict to be for plain traffic, never make the layer accept an unverified envelope.

Required Methods

fn mode(&self, request: &PolicyRequest<'_>) -> EnvelopeMode

The mode for this op.

Provided Methods

fn unresolved_mode(&self) -> EnvelopeMode

The mode for traffic the layer cannot attribute to one op: a route the router matched but the resolver cannot bind (a wrong mount prefix, a hand-written route; decision S2), or a /rpc/batch body whose frames it cannot read (B1). Under Required the first fails closed with a 500 unless the route is allow-listed (super::EnvelopeLayerBuilder::allow_unresolved), and the second is refused. Under a non-Required answer, both pass through, and so does a method the schema does not generate on a generated path (otherwise the layer’s 405), unsigned.

The default is Required, which fails closed: a per-op closure cannot say what it would have answered for an op nobody can name. An EnvelopeMode used as the policy answers itself. For a closure, super::EnvelopeLayerBuilder::unresolved_mode replaces it explicitly, without writing a type.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl EnvelopePolicy for EnvelopeMode

impl<F> EnvelopePolicy for F

where F: Fn(&PolicyRequest<'_>) -> EnvelopeMode + Send + Sync + 'static,