nx_cache_control.nx

cache_control.nx -- parse HTTP Cache-Control header. RFC 7234 §5.2. Controls caching behaviour at every level (browser, proxy, CDN, reverse-proxy). Getting it right is the difference between a fast site and a stampeded origin. Format: comma-separated directives, some with arguments. Cache-Control: max-age=3600, public Cache-Control: no-store Cache-Control: private, max-age=0, must-revalidate Cache-Control: public, max-age=31536000, immutable Cache-Control: no-cache, s-maxage=600 We parse into a typed CacheControl struct with flag bits for the named directives + integer values for max-age / s-maxage / max-stale / min-fresh / stale-while-revalidate. Invariants: CC1 Empty input yields default CacheControl (all flags 0, ages = -1 meaning \"not specified\"). CC2 Unknown directives silently ignored per RFC 7234 §5.2 tolerance rule. CC3 Directive names are case-insensitive (we lowercase on match). Argument values are case-sensitive integers.