gag - Gateway alias generator

gag [ -a ] [ -bbbn_file ] [ -ccnews_file ] [ -iinnnews_file ] [ -nbnews_file ] [ -dmmdf_dir ] [ -ssendmail_file ] [ -tPP_shell ] [ -uPP_user ] [ -b ] [ -p ] [ file ]

Gag reads a control file and builds entries for sendmail(8), BBN, MMDF(8), and PP(8) alias files, as well as Netnews(1) sys file entries. It is an auxiliary program for helping to maintain a mail/news gateway operation. A typical gag file sets up default values for all the parameters, then contains a list of newsgroup-mailing list pairs. Group-specific values can override the defaults.

Gag input is fairly free-form. It ignores C-style comments, and whitespace is allowed anywhere. There are a couple of dozen keywords, and case is significant; most of the keywords are parameters used to control the gatewaying. Quoted strings are written as they are in C, except they may not span lines.

Using the parameters enumerated below, gag can write six different sets of alias files:

BBN	if the ``-b'' flag is used
MMDF	if the ``-m'' flag is used
B News	if the ``-n'' flag is used
C News	if the ``-c'' flag is used
InterNetNews	if the ``-i'' flag is used
Sendmail	if the ``-s'' flag is used
PP shell	If the ``-t'' flag is used
PP user	if the ``-u'' flag is used

    sed '/--START-OF-GATEWAY-OUTPUT-/,/--END-OF-GATEWAY-OUTPUT-/d' \
	</var/lib/news/sys >/tmp/sys
    gag -n - <gag.data >>/tmp/sys
    mv /tmp/sys /var/lib/news/sys

Gag normally complains about attempts to gateway groups that are not in the news active file; use the ``-a'' suppresses this check, assuming that all named groups are valid.

BBN-style aliases can't pipe into a command with parameters. For example, sendmail can have an entry like this in /etc/aliases(5):

post-bboard:	"|/usr/bin/mail2news -n bbn.bboard \
	-o 'BBN News/Mail Gateway' \
	-d bbn"

bboard-gate:	@mailer.bbn.com { "news|/usr/lib/news/.admin/gate-bboard" }
	bboard-gate@mailer.bbn.com

#! /bin/sh
##  This script is on the "bboard" mailing list.
exec /usr/bin/mail2news -n bbn.bboard \
	-o "BBN News/Mail Gateway" \
	-d bbn

MMDF aliases are similar to sendmail's, except that the the scripts are run under a specified user id (see below).

PP uses two files, a shell and user file, whose format is not described here.

Some sites want to create mail aliases that forward into each newsgroup; that is, mail sent to ``comp-foo-bar'' should get posted to the ``comp.foo.bar'' newsgroup. If the ``-p'' flag is used, then each gatewayed group will get such an alias created. The mkmailpost(1L) command can be used to create gag ``mailpost'' commands for all entries in the news active file. Note that using mkmailpost and the ``-p'' flag will almost certainly result in the creation of duplicate aliases.

The parameters that control the gatewaying are:

directory

The directory where the BBN alias scripts are kept. (In the above example, the directory is /usr/lib/news/.admin.)

distributions

A space-separated list of distributions to forward from news to mail. In most cases, this will be the full set of distributions received, but it can be convenient, for example, to not forward regional articles out to a world-wide mailing list. With distributions set to ``world usa na'' then the news sys entry for ``comp.foo'' will have this in the second field:

<site>:\
  world,!world.all,usa,!usa.all,na,!na.all,comp.foo,!comp.foo.all\
  <rest of entry>

inews flags

These are flags to pass on to inews(8) when gatewaying a mail message into netnews. They are put on the news2mail (1) command line, which will pass them along. A common use is to set a default distribution or organization.

mail2news

The full pathname of the mail2news program.

mailcontact

This is the name of the person listed in the ``For more information, contact'' part of the header generated by news2mail.

mailhost

When remote mailing lists are gatewayed into local newsgroups, it can often be convenient to provide a local alias that forwards on to the remote host. For example, if the list ``info-foo'' is maintained at ``vax.host.edu'' then it is possible to create a local alias that just forwards to ``info-foo@vax.host.edu.''

mailinglist

If set to ``true,'' then gag will write aliases that forward on to the list at the current mailhost; if set to ``false'' than no such aliases will be written.

moderator

If set, then the value is put on the mail2news command line with the ``-a'' flag. This is useful for making a semi-moderated one-way gateway.

news2mail

The full pathname of the news2mail program.

organization

If set, then the value is put on the mail2news command line with the ``-o'' flag.

owner

If set, then all sendmail aliases also have an ``owner-'' version, with this value as the recipient, to receive trouble reports.

request_address

Most mailing lists have a ``-request'' address to handle list administration. When gatewaying the list ``info-foo'' if the maintenance address isn't ``info-foo-request'' set this parameter to the proper address.

site

This is the name of the site to use in the news sys file; ``gateway'' is a common choice.

user

When running scripts under MMDF (either normal or with the BBN style) a userid to setuid to must be given.

Note that there is some overlap in these parameters. In particular the ``moderator'' and ``organization'' parameters can really be subsumed by the ``inews flags'' parameter. They are explicitly called out, however, for convenience in specifying the types of gatewaying. For example, while all gatewayed groups might go out with the same distribution, only some might need an Approved: header line.

A gag file is composed of intermixed parts of three different constructs: defaults, mail/news posting entries, mail/news gateway entries.

Individual groups can override the default parameters. The defaults can be changed at any time, and retain the new value for the rest of the file or until changed again. For example, most mail aliases will be ``owned'' by postmaster, but it might be convenient to set the forwarding address on specific aliases to someone else. For example:

/* Send gateway complaints to postmaster */
default owner = "postmaster";

/* The "animals" list is privately maintained. */ gateway bbn.animals animal-rights owner = "canus-major"; The syntax is explained in more detail, below.

A default parameter assignment looks like one of the following:

default <parameter> = true ;
default <parameter> = false ;
default <parameter> = "string value" ;
default <parameter> = dotify ( "value" ) ;

A gateway declaration looks like this:

gateway <newsgroup> <mailinglist>
	[ parameter settings ] ;

To set up a simple unidirectional newsgroup/mailing list gateway, use a ``mailpost'' declaration:

mailpost <newsgroup> ;

Gag doesn't free most of the memory that it allocates; in essence, the entire input must fit into the process space.

In generating news sys file entries, remember that the command is a sprintf(3) format string, and any percent signs (%) must be doubled or they will be taken as a formatting control.

mail2news(1), mkmailpost(1), news2mail(1).

Rich $alz <rsalz@bbn.com>, replacing some m4 scripts that

Erik E. Fair <fair@apple.com> wrote.

Piete Brooks <pb@computer-lab.cambridge.ac.uk> provided the PP support.