Hi all,

A network server program I'm writing suddenly developed a requirement to
act as a minimal Web server. No problem, sez I, I'll just add the
necessary functionality. The world abounds with 100-line demo Web servers
touting the virtues of various languages/class libraries, so it can't be
that hard.

Well, to do it *right*, it's not quite that simple, at least if "right"
includes honoring the various cache control headers. Here's the problem:
RFC 2616 says that the If-Modified-Since header value must be just a
timestamp. But both Netscape 4.x and MSIE 4.x/5.x send something like:

   If-Modified-Since: Wed, 08 Mar 2000 16:47:02 GMT; length=5328

What the heck is this "length" stuff? It's always the length of the file
the last time it was fetched, but how am I supposed to interpret it?
Obviously, if 95% of the world's web browsers send it, I can't regard the
header as invalid (which is what I was doing), but does anyone know how
this should be used? It's certainly not part of the RFC.

-- Bruce


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