Function check_route_limits 

pub fn check_route_limits(
    limits: &RequestLimits,
    headers: &HeaderMap,
    content_length: Option<u64>,
) -> Option<RouteLimitViolation>

Check a request against a route’s crate::config::RequestLimits (DW-027), right after route resolution. content_length is the request body’s exact size when declared (size_hint().exact() — Content-Length for h1, the content-length pseudo-header for h2), None when the length is unknown (streaming). Header checks are header-count first (cheapest to report), then header bytes, then the declared body size.