• Werner Koch's avatar
    dirmngr: Implement experimental SRV record lookup for WKD. · 88dc3af3
    Werner Koch authored
    * dirmngr/server.c (cmd_wkd_get): Support SRV records.
    This patch changes the way a WKD query is done.  Now we first look for
    a SRV record for service "openpgpkey" and port "tcp" under the
    to-be-queried domain.  If such a record was found and the target host
    matches the to-be-queried domain or is a suffix to that domain, that
    target host is used instead of the domain name.  The SRV record also
    allows to change the port and obviously can be used for
    For example a query for the submission address of example.org with the
    SRV record specification
    _openpgpkey._tcp        IN     SRV   0 0  0    wkd.foo.org.
                            IN     SRV   0 0  0    wkd.example.net.
                            IN     SRV   0 0  4711 wkd.example.org.
    (queried using the name "_openpgpkey._tcp.example.org") would fetch
    from this URL:
    Note that the first two SRV records won't be used because foo.org and
    example.net do not match example.org.  We require that the target host
    is identical to the domain or be a subdomain of it.  This is so that
    an attacker modifying the SRV records needs to setup a server in a
    sub-domain of the actual domain and can't use an arbitrary domain.
    Whether this is a sufficient requirement is not clear and needs
    further discussion.
    Signed-off-by: 's avatarWerner Koch <wk@gnupg.org>
server.c 72.3 KB