Function nanocoap_cache_request_lookup

pub unsafe extern "C" fn nanocoap_cache_request_lookup(
    req: *const coap_pkt_t,
) -> *mut nanocoap_cache_entry_t

@brief Performs a cache lookup based on the @p req.

@param[in] req The request to calculate the cache-key

@return An existing cache entry on cache hit @return NULL on cache miss