=head1 NAME

crlpublish - CRL publisher configuration syntax

=head1 DESCRIPTION

crlpublish is a utility for pushing CRL updates to one or more target servers
where other applications and processes pick them up. These are commonly
referred to as Issuing Distribution Points and should ideally be encoded
into the CRLs and CA certificates themselves.

Often, there is not enough information encoded in the CRL and in the operating
environment to deduce how this publishing should be accomplished. In those
cases, details must be provided through configuration files. Their format,
syntax, and usage are documented here.

=head1 CONFIG FILE LOCATIONS

Configuration files should be placed in one of these directories:

=over 

=item *

/etc/crlpublish/*.cfg

=item *

$HOME/.crlpublish/*.cfg

=back

Additionally, as in-situ compatibility with the older crlpublisher.sh script
is supported, the following directories are scanned for legacy config files:

=over

=item *

/etc/crlpublisher/*.conf

=item *

$HOME/.crlpublisher/*.conf

=back

There is no particular naming convention required, nor even a need to use more
than one file. Any file with the proper extension will be imported, in
directory order.

=head1 CONFIG FILE FORMAT

Although there is a notion of an old and a new file format, they are read in
by the same parser. Using "newness" in an old-style .conf file will generate
a runtime error.

Both file formats use a namedAttribute="value" basic syntax.

There the similarity ends. The old version was parsed by the shell, and so was
intolerant of whitespace and liberal about quoting and content. Backticks and
other shell language were legal, although it is not known if anyone ever used
such. crlpublish does not support this usage.

The new format is parsed by Perl, and so backticks are not permitted. Quotes
are optional, and whitespace is tolerated at the beginning and end of any line,
and between the variable, equals, and value. Extra space is dropped; if you
need control, use single or double quotes around the value.

Also, the new format supports sections using the ini style [sectionName] syntax.
The brackets are treated as quotes, and whitespace within is not dropped.

=head1 CONFIG FILE EXAMPLES

An example of the old syntax follows:

 publisher=scp
 remoteUser=crlowner
 remoteHost=my.target.server.com
 remoteLocation=crl/thisca.crl
 privateKey=/path/to/ssh/privateKeyFile
 issuerDn="CN=My CA,O=Example Inc.,C=ME"

A roughly equivalent example of the new syntax follows:

 [defaults]
 publishMethod=scp
 remoteUser=crlowner

 [CN=My CA,O=Example Inc.,C=ME]
 remotePath=crl
 remoteFile=thisca.crl
 remoteHost=crl.target.server.com

 [crl.target.server.com]
 remoteHost=crl-1.target.server.com,crl-2.target.server.com

Note that such verbosity is not generally required, as will be explained
below, and there is some redundancy to illustrate capabilities. The section
for my.target.server.com needn't exist; the comma-separated list could have
been specified above in the defaults, or in the issuerDn section.

=head1 RUNTIME CONFIG RESOLVING ORDER

In point of fact, any of those variables could have appeared in any of those
sections, and the configuration parser would happily import and supply them
at the appropriate point in the resolution order; see below.

Cascaded defaults are supported by creating a container object and copying
the configuration name-value pairs into that container in a particular order,
allowing attributes of the same name to overwrite earlier values.

First, fixed defaults are applied. At present, this is only publishMethod=scp.
Next, the parsed parts of the Issuing Distribution Point URL, if any, are
copied in, followed by all values in the [defaults] section. Then, the values
from the issuerDn section are copied the Issuer Distribution Point URL.
Finally, values from the remoteHost section are copied in.

In this way, it is often unnecessary to supply any configuration at all, if
the Issuing Distribution Point is supplied in the CRL. See below for defaults.

It is also worth noting that attributes can be named anything and will be
passed into the container object. No core code changes will be required to
support new attributes for new publishing methods. It is up to the
publishMethod implementation to make meaning of them.

=head1 ATTRIBUTE NAMES AND AND MEANINGS

Additional publishMethods may require their own attributes.

=head2 publishMethod

Specify the publishing method to use. Currently, only scp is supported.

=head2 publisher

Equivalent to publishMethod; kept for legacy compatibility.

=head2 issuerDn

Only meaningful in a legacy style config file; specifies the issuerDn
to which that config file refers. The new config syntax specifies this
in a section name.

=head2 remoteUser

Specify the remote username to connect as. If not specified, none will
be specified on the command line, and scp will default to the current
user on the originating host.

=head2 remoteHost

Specify the remote host to connect to. It can be a hostname, short or
long, or an address, IPv4 or IPv6. It will be passed verbatim to scp.
If not specified, it will be parsed from the CRL if available.

Multiple targets are supported by supplying a comma-separated list.
Whitespace around the commas is tolerated.

=head2 remoteFile

Specify the filename to publish the CRL as, since crlpublish was probably
invoked using a temporary file with a randomized name. If not specified,
it will be parsed from the CRL if available.

=head2 remotePath

Specify the subdirectory to place the remoteFile in. Relative paths are
relative to the remoteUser's home directory on the remoteHost. It must
exist. If not specified, it will be parsed from the CRL if available.

=head2 remoteLocation

Combines remotePath and remoteFile into a single directive. Kept for
legacy compatibility; stored internally as remotePath and remoteFile.

=head1 AUTHOR

Kevin Cody-Little <kcody@cpan.org>