ip/httpd/httpd doesn't dynamically create web pages indexing
directories the way some other httpd's can be configured to (apache is
an obvious example here).  This is probably to the good; it prevents
people from snooping around your directory structure unnecessarily.
However, it can also be annoying; for instance, if you want to expose
the contents of a directory hierarchy to the world.  A simple solution
there is to simply write a script that creates directory listings for
you, and then use it to generate static HTML pages, and create links
to those.  However, that's annoying because (a) you have to maintain
the pages, and (b) they clutter up your namespace with things you
ordinarily wouldn't have there.

But nothing is stopping us from implementing a tool to do that
automatically, so I did just that.  Here is webls, a server in the
same vein as man2html (indeed, I started with the man2html source when
building webls), to be run via the /magic, er, magic, and which
generates ls-like output for a directory on the fly.

So far, it seems to work rather well.  I've only tested it myself, I
guess, and rather lightly, but it's simple enough to not be a big
deal.  It also has support for specifying two files,
/sys/lib/webls.allowed and /sys/lib/webls.denied for restricting
access to what parts of the web space it will create listings for (the
two files fit together in a pretty obvious way, but the rules for them
are specified in the source).  In a nutshell, add lines to
webls.allowed with regular expressions for what you want to be
visible, and regular expressions in webls.denied for what you don't
want to be visible.  Webls.allowed overrides webls.denied.  If
webls.allowed exists and webls.denied does not, then access is only
granted for filenames match regular expressions explicitly listed in
webls.allowed.  If webls.denied exists and not webls.allowed, then
access is only denied for requests for directories explicitly listed
in webls.denied.  If neither exists, access is granted everywhere; the
rationale here is that only things in your publically viewable web
namespace are visible, anyhow..  A safe thing to do is simply, ``echo
'.*' > /sys/lib/webls.denied' and then explicitly list those things
you want to be listable.

Anyway, a patch to /sys/src/cmd/ip/httpd/mkfile follows, as well
as the default `turn everything off' webls.denied and webls.c itself.
This is, I think, useful enough to go in the base distribution.

	- Dan C.

brahma% ape/diff -c /n/sources/plan9/sys/src/cmd/ip/httpd/mkfile mkfile
*** /n/sources/plan9/sys/src/cmd/ip/httpd/mkfile	Wed Nov 27 19:23:25 2002
--- mkfile	Mon Sep 29 01:44:15 2003
***************
*** 10,15 ****
--- 10,16 ----
  	man2html\
  	save\
  	wikipost\
+ 	webls\

  LIB=libhttps.a.$O

brahma%