Fix to declare missing MAXLOGNAME properly

[obache]

Use LOGIN_NAME_MAX if it is available for the condition.

[elliefm]

Sorry this took so long to look at. It looks good, thanks. I've identified one other change you might want to make while you're in there.

[elliefm]

I went looking for the significance of this being LOGIN_NAME_MAX - 1 and not just LOGIN_NAME_MAX. Apparently LOGIN_NAME_MAX includes the terminating nil character. It's not immediately clear to me whether MAXLOGNAME does too, or not. But it doesn't matter anyway, because the only place this is used is here:

    char buf[MAXLOGNAME + MAXDOMNAME + MAX_MAILBOX_BUFFER];

which is MAXLOGNAME + 20 + 1024. But a few lines later:

        r = recvfrom(soc, buf, 511, 0, sfrom, &sfromsiz);

We only ever use 511 bytes of this buffer! Which is more than accommodated by the 1024 from MAX_MAILBOX_BUFFER, so unless MAXLOGNAME is negative its value is irrelevant.

Perhaps we should amend the recvfrom line to actually use the whole buffer, something like:

        r = recvfrom(soc, buf, sizeof(buf) - 1, 0, sfrom, &sfromsiz);

Do you want to do this too while you're in there? I'm not familiar with the fud protocol, so I don't know whether this would be a useful improvement in practice, but it's better code.

[obache]

I thought, but I'm not familiar too, so stay as it is.

To begin with, max length of user name (and domain name) should probably rely on Cyrus implementation (or email related RFC), not OS limitation....? mailbox and domain name are in full mailbox name, so just MAX_MAILBOX_BUFFER is sufficient...?