On Sat, Feb 04 2023, Jeff King wrote:
On Fri, Feb 03, 2023 at 10:12:27PM +0100, Ævar Arnfjörð Bjarmason wrote:
[...]
quoted
I agree that "give this to the auth helper" might be useful in general,
but our current documentation says:
To use the tool, `imap.folder` and either `imap.tunnel` or `imap.host` must be set
to appropriate values.
And the docs for "imap.tunnel" say "Required when imap.host is not set",
and "imap.host" says "Ignored when imap.tunnel is set, but required
otherwise".
Perhaps we should bless this as an accidental feature instead of my
proposed patch, but that's why I made this change. It seemed like an
unintentional bug that nobody intended.
Yes, I agree that the scenario I'm giving is contrary to what the docs
say. But IMHO it is worth preferring what the code does now versus what
the docs say. The current behavior misbehaves if you configure things
badly (accidentally mix and match imap.host and imap.tunnel). Your new
behavior misbehaves if you have two correctly-configure imap stanzas
(both with a host/tunnel combo). Those are both fairly unlikely
scenarios, and the outcomes are similar (we mix up credentials), but:
1. In general, all things being equal, I'd rather trust the code as
the status quo. People will complain if you break their working
setup. They won't if you fix the documentation.
2. In the current behavior, if it's doing the wrong thing, your next
step is to fix your configuration (don't mix and match imap.host
and imap.tunnel). In your proposed behavior, there is no fix. You
are simply not allowed to use two different imap tunnels with
credential helpers, because the helpers don't receive enough
context to distinguish them.
And that is not even "two imap tunnels in the same config". It is
really per user. If I have two repositories, each with
"imap.tunnel" in their local config, they will still invoke the
same credential helpers, and both will just see host=tunnel. The
namespace for "host" really is global and should be unique (ideally
across the Internet, but at the very least among the hosts that the
user contacts).
One fix would be to pass the tunnel command as the hostname. But even
that has potential problems. Certainly you'd have to tweak it (it's a
shell command, and hostnames have syntactic restrictions, including
forbidding newlines). And you'd probably want to swap out protocol=imap
for something else. But I'm not sure if helpers may complain (e.g., I
seem to recall that the osxkeychain helper translates protocol strings
into integer constants that the keychain API understands).
quoted
Especially as you're focusing on the case where it contrary to the docs
would do what you mean, but consider (same as the doc examples, but the
domains are changed):
[imap]
folder = "INBOX.Drafts"
host = imap://imap.bar.com
user = bob
pass = p4ssw0rd
[imap]
folder = "INBOX.Drafts"
tunnel = "ssh -q -C user@foo.com /usr/bin/imapd ./Maildir 2> /dev/null"
I.e. I have a config for "bar.com" I tried earlier, but now I'm trying
to connect to "foo.com", because I read the docs and notice it prefers
"tunnel" to "host" I think it's going to ignore that "imap.host", but
it's going to provide the password for bar.com to foo.com if challenged.
Yes, that's a rather unfortunate effect of the way we do config parsing
(it looks to the user like stanzas, but we don't parse it that way; the
second stanza could even be in a different file!).
Though as I said above, I still think this case does not justify making
the code change, I do think it's the most compelling argument, and would
make sense to include in the commit message if we did want to do this.
quoted
So I think if we want to keep this it would be better to have a
imap.tunnel.credentialHost or something, to avoid conflating the two.
Yes, there are many config schemes that would avoid this problem. If you
are going to tie the two together, I think it would make sense to use
real subsections based on the host-name, like:
# hostname is the subsection key; it also becomes a label when
# necessary
[imap "example.com"]
# does not even need to mention a hostname. We'll assume example.com
# here.
tunnel = "any-command"
# assumes example.com as hostname; not needed if you are using a
# tunnel, of course
protocol = imaps
But I would not bother going to that work myself. IMHO imap-send is
somewhat of an abomination, and I'd actually be just as happy if it went
away. But what you are doing seems to go totally in the wrong direction
to me (keeping it, but breaking a rare but working use case to the
benefit of a rare but broken misconfiguration).
quoted
quoted
Of course if you don't set imap.host, then we don't have anything useful
to say. But as you saw, in that case imap-send will default the host
field to the word "tunnel".
Isn't that more of a suggestion that nobody cares about this? Presumably
if we had users trying to get this to work someone would have complained
that they wanted a custom string rather than "tunnel", as the auth
helper isn't very helpful in that case...
Not if they did:
[imap]
host = example.com
tunnel = some-command
Yes, but how would they have ended up doing that? By discarding the
documentation and throwing things at the wall & hoping they'd stick?
I take all your general points above, and generally agree with them. Re
#1 we should generally prefer current behavior over the docs, and re #2:
Yes, I agree this might be useful in princple, and hardcoding
"host=tunnel" doesn't leave a way to pass a custom "host to the auth
helper.
I also don't care enough to argue about it, so I'll leave the first hunk
here out of any re-roll. We'll continue to pass "host" down in that
case, i.e. I'll only adjust the error messages.
I just don't get how anyone could have come to rely on this so that we'd
care about supporting it.
Because mutt has a feature that looks similar, users might have
configured git-imap-send thinking it might do the same thing, and gotten
lucky?
I guess in principle that could be true, but I think it's more likely
that nobody's ever had reason to use it that way. I.e. if you use the
"tunnel" the way the docs suggest you won't hit the credential helper,
as you're authenticating with "ssh", and using "imapd" to directly
operate on a Maildir path.