bugs: Web proxies

This is a list of bugs and non-optimal behaviours by Web proxy/caches. It isn't complete; please send me any more that you find.

Because many vendors stipulate in their licenses that some information about their products can't be published, the list is amalgamated. Bugs shown here are exhibited in at least one commercial Web proxy/cache product, and some are in several.

You can also see a similar listing for Web servers.

Interpretation of Cache-Control headers. Most if not all current caches do not properly handle. CC response headers. Although this is understandable, as they're new and have been in flux, it's critical that this be done right. [ more info]
Generation of Date headers. Date strings in the HTTP are case-sensitive; they should not be all caps. Also, a proxy should not modify a Date header in transit.
Caching of stale objects. An object coming into the cache that is stale (has a LM header equivalent to the Date header) is still cacheable; it can be validated. Some caches will not keep a copy.
HTTP specification used. Many cache vendors are still referring to RFC2068 for protocol information; the correct document to reference is RFC2616.