"Michael H. Warfield" <mhw(_at_)wittsend(_dot_)com> writes:
Problem 1:
When Trying to reference IPv6 only host names (no DNS "A" record,
only DNS "AAAA" records), fetchmail does not work at all. It refuses
because it can not resolve the host canonical name using gethostbyname.
For hosts with both A records and AAAA records, fetchmail works, but
for the wrong reason. It resolves the host canonical name using the
IPv4 address and then uses IPv6 to contact the host.
My vote, although not IPv6 user, but maintainer of a package that has to
do IPv6: Go for the OpenSSH approach, with a stub IPv4-only getaddrinfo,
to streamline the program, using getaddrinfo everywhere. Let auto/conf/igure's
AC_REPLACE_FUNCS deal with this, not a collection of runaway #ifdefs.
Problem 2 (this one is ugly):
The code in checkaliases compares addresses to see when to
names refer to the same system.
It's not only ugly, but also plain wrong, which has been lingering
around for too long.
1. Mail routing is done via DNS MX RRs. gethostbyname looks at DNS A
RRs, these do not convey any information relevant to mail. IP
resolution is unrelated to mail domain aliasing, and will only lead
to false positives.
2. DNS MX RRs do not carry any information suitable to figure if a
domain is an alias for another. The same MX server can well host
several *distinct* virtual domains. MX lookups would yield false
positives for sure. While this should not bite the fetchmail user
because it's the server's task to sort the mail into the right
multidrop box, it's evil when fetchmail is pulling for several
domains.
3. Only sendmail needs this functionality, because only sendmail offers
the brain-dead "one global namespace" virtual domains, that expose
each account in all virtual domains (effectively, sendmail virtual
domains are just aliases for the localhost). Other software, Postfix,
qmail, probably Courier, Exim as well, has a separate name space for
each virtual domain. I believe the sendmail-style virtual domains are
not in widespread use nowadays because of the inevitable collisions.
=> The user should list all domain aliases in her configuration file.
My vote: drop this IP comparison stuff and get rid of the IPv6 head
aches in the same go.
--
Matthias Andree