Function extract_request_x_forwarded_for 

pub fn extract_request_x_forwarded_for<B>(
    request: &Request<B>,
) -> Result<Option<Vec<IpAddr>>, Error>

Extract the untrusted X-Forwarded-For chain from a complete request.

This reads request.headers() and delegates to extract_header_x_forwarded_for, preserving its missing, repeated-line, and malformed-value behavior. The returned assertions remain untrusted.