Struct UserAgentLayer 

pub struct UserAgentLayer { /* private fields */ }

Tower layer that sanitizes the inbound User-Agent header in place.

Reads the request’s User-Agent once, applies a small set of normalization rules (length cap on a UTF-8 char boundary, ASCII control stripping, whitespace collapsing, trimming), and rewrites the header value before delegating to the inner service. If the sanitized result is empty the header is removed entirely so downstream consumers see the same “missing” state they handle today.

Because the layer mutates the request header itself, every downstream reader — ClientInfo, the cookie session middleware, audit logging, fingerprint hashing — observes the cleaned value with no further plumbing.

Layer ordering

Install UserAgentLayer before any layer or handler that reads User-Agent. In axum that means it must be added with a .layer(...) call that comes after (i.e. wraps) the consumer:

use axum::{Router, routing::get};
use modo::middleware::UserAgentLayer;

let app: Router = Router::new()
    .route("/", get(|| async { "ok" }))
    .layer(UserAgentLayer::new());

Implementations

impl UserAgentLayer

pub fn new() -> Self

Create a layer with the default 512-byte sanitization cap.

pub fn with_max_length(max_len: usize) -> Self

Create a layer with a custom byte-length cap.

Trait Implementations

impl Clone for UserAgentLayer

fn clone(&self) -> UserAgentLayer

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for UserAgentLayer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for UserAgentLayer

fn default() -> Self

Returns the “default value” for a type.

impl<S> Layer<S> for UserAgentLayer

type Service = UserAgentMiddleware<S>

The wrapped service

fn layer(&self, inner: S) -> Self::Service

Wrap the given service with the middleware, returning a new service that has been decorated with the middleware.

impl Copy for UserAgentLayer