WN provides some features by auxiliary modules. These are separate C programs called by the server to provide some function like authorization (authentication) or indexed searches or database access. The current release of WN has a module for authorization using the HTTP/1.1 Basic Authentication scheme supported by most clients and future releases will have a module to do index searches.
The current version also has the support infrastructure or "hooks" for several services which maintainers may wish to create.
The index.cache in each directory is in fact a small flat
database containing characteristics of that directory and the files
contained in it. This can be replaced on a per directory basis by a user
supplied module to provide the same information. In the index.wn file for such a
directory you should create a directory
directive entry like:
Cache-Module=/full/path/to/foo
The program "foo" should be an interface to your
database. It is permissible to follow "foo" in this line
with any desired arguments to be passed to it. The program
"foo" should read the environment variable WN_KEY which will
contain everything after the final '/' in the URL being
served. Based on this key it should return a single line in the format of an index.cache file. Any
"File=" directives in
an index.wn file which
contains a "Cache-Module="
directive will be ignored.
You may wish the cache module function to have access to more information
about the request. If you put the directive "Default-attributes=cgi"
before the "Cache-Module="
directive then all the CGI environment
variables will be set.
If the file cache module encounters an error, such as no entry corresponding to the supplied key, it should return nothing and exit with a negative status. This signals the server to return an appropriate error message.
It is perhaps more useful to have the files being returned reside in a
database. To use such a database interface called "bar", in
the index.wn file for its
directory you should create a directory
directive entry like:
File-Module=/full/path/to/bar
The program "bar" should be an interface to your database.
It should read the environment variable WN_KEY which will
contain everything after the final '/' in the URL being
served. Based on this key it should return a document to be served
(perhaps after processing with wrappers or includes). When a file module
is used it is also necessary to either use a "Cache-Module=" or have
an actual index.cache file with the name of all documents
which might be returned by the database or to have an
index.cache file created from an index.wn file containing the
directory directive "Attributes=serveall".
If the file module encounters an error, such as no document corresponding
to the supplied key, it should return an appropriate error message of the
same content-type as the requested document.
As with cache modules, you may wish the file module
function to have access to more information about the request. If you
put the directive "Default-attributes=cgi"
before the "File-Module=" directive
in your index.wn file then
all the CGI environment variables will be
set.
Authorization requests in WN are normally handled by an authorization module. The current release contains a Basic Authentication module and a prototype implementation of Digest Authentication, but users are invited to provide their own.
Warning: I would strongly advise against using basic authentication described here to protect sensitive information on a server which runs on system on which untrusted users have accounts.
The contents the Authorization: request header is passed to
the module on the UNIX stdin(3)
stream (as of version 1.10).
The server expects this module to exit with a status indicating that
access is granted, denied, or that an error occurred. Anyone writing an
authorization module should consult the file
/wnauth/wnauth.h. The "#defines" listed there
specify the error status to use for granting, denying or indicating
certain errors.
To use a user supplied authorization module named authmod
the index.wn file of each
directory requiring authorization should contain lines like:
Authorization-realm=myrealm
Authorization-module=/full/path/to/authmod
Authorization-type=basic
The program authmod should indicate the granting or denial
of authorization by its exit status as described above. The "Authorization-realm="
is a designation which is sent to the client with the authorization
request allowing the client to decide whether the user has already
supplied a password which can be reused (if the realm is the same as when
the password was supplied) or if a new password needs to be entered.
Indexed searches can be supported in WN by auxiliary modules.
Two such modules are provided as examples and maintainers may wish to
create others. To use such a module you should have an HTML <form>
action be something like:
http://host/dir/search=index
Then in the index.wn file
in the directory record you should have a line like:
Search-Module=/full/path/to/searchmod
The program searchmod should read the CGI environment
variable QUERY_STRING and
return a partial HTML document. The typical case would be the program
returns an unordered list of anchors to documents containing a match to
the query string. This list can be wrapped by including a "Searchwrapper="
directory directive. If it is not, a default wrapper with text like
"Here are the matches for your search." is supplied.
Two simple examples of a search-module (written in perl) are included in the distribution in
the files bin/wnseven_m and bin/wnsectsearch.