The mail-auth crate doesn't support 1024 bit RSA keys, which are
currently the dominant size of key used by senders at scale.
It is not possible to even configure a 2048 bit RSA key in some DNS
providers, which blocks widespread adoption of larger key sizes.
This commit pulls in the cfdkim crate as an alternative implementation.
I'm not happy with this implementation because the API of the crate
defeats some caching optimizations, doesn't support certain signing
attributes that are supported by mail-auth and the generated header isn't
nicely wrapped.
We'll likely "do something" to resolve this in a future commit.
For now, this implementation is enabled by setting `use_cf = true`
in the signing parameters.
I couldn't find definitive evidence that rsa-1024 has been broken,
but I did find some cases where eg: GPG had a side-channel attack
that could break PGP keys of that size, so it's easy to imagine
that other similar approaches might work for other software.
Regardless, the actual limitation comes from the Rust ring crate:
https://docs.rs/ring/latest/ring/signature/struct.RsaKeyPair.html#method.from_pkcs8
> Only two-prime (not multi-prime) keys are supported. The public modulus
> (n) must be at least 2047 bits. The public modulus must be no larger
> than 4096 bits. It is recommended that the public modulus be exactly
> 2048 or 3072 bits. The public exponent must be at least 65537.
Refine the error message to be more factual.
In the future I want to add separate packages for just the proxy
server, but for now this is the most expedient way to deliver
the binary.
refs: https://github.com/KumoCorp/kumomta/issues/45
```console
$ kcli --help
KumoMTA CLI.
Full docs available at: <https://docs.kumomta.com>
Usage: kcli --endpoint <ENDPOINT> <COMMAND>
Commands:
bounce
Administratively bounce messages in matching queues
set-log-filter
Changes the diagnostic log filter
help
Print this message or the help of the given subcommand(s)
Options:
--endpoint <ENDPOINT>
URL to reach the KumoMTA HTTP API
-h, --help
Print help (see a summary with '-h')
-V, --version
Print version
```
```console
$ kcli bounce --help
Administratively bounce messages in matching queues.
Each individual message that is bounced will generate a log record capturing the event and then be removed from the spool.
Make sure that you mean it, as there is no going back!
The bounce will be applied immediately to queued messages, and the directive will remain in effect for the duration specified, causing newly received messages or messages that were in a transient state at the time the directive was received, to also be bounced as they are placed back into the matching queue(s).
Usage: kcli --endpoint <ENDPOINT> bounce [OPTIONS] --reason <REASON>
Options:
--domain <DOMAIN>
The domain name to match. If omitted, any domains will match!
--campaign <CAMPAIGN>
The campaign name to match. If omitted, any campaigns will match!
--tenant <TENANT>
The tenant name to match. If omitted, any tenant will match!
--reason <REASON>
The reason to log in the delivery logs
--everything
Purge all queues
--duration <DURATION>
The duration over which matching messages will continue to bounce. The default is '5m'
-h, --help
Print help (see a summary with '-h')
```
```console
$ kcli set-log-filter --help
Changes the diagnostic log filter
See <https://docs.kumomta.com/reference/kumo/set_diagnostic_log_filter/> for more information about the log filter syntax.
Usage: kcli --endpoint <ENDPOINT> set-log-filter <FILTER>
Arguments:
<FILTER>
Options:
-h, --help Print help
```
refs: https://github.com/KumoCorp/kumomta/issues/55
Systemd doesn't terminate processes using SIGINT, so we didn't
get a chance to flush logs or messages to spool.
This should address that.
refs: https://github.com/KumoCorp/kumomta/issues/46
This commit also includes a policy helper
`policy_extras.listener_domains` to make it convenient to define
listener domains in toml and/or json files.
To facilitate this, the DomainMap rust structure has been exposed
to lua code via the new `kumo.domain_map.new` function.
Switch the configuration plumbing for pools and sources to be pull-based
rather than push based.
In other words, rather than defining them in the `init` event,
you now need to supply them to the new `get_egress_pool` and
`get_egress_source` events.
Data is cached by default for 1 minute. This allows for new sources
to come into being on-demand, and for data to age out and change
over time, without requiring that the server be restarted.
This commit updates the reference section, but there is some content
in the user guide that refers to the old style of configuration that
will need to be updated.
refs: https://github.com/KumoCorp/kumomta/issues/13
Produces an error like:
```
; KUMOD_LOG=kumod=info ./target/debug/kumod --policy simple_policy.lua
2023-05-16T18:16:02.112017Z INFO main kumod::memory: using limits: soft=Some("101.22 GB"), hard=Some("134.96 GB")
Error: callback error
stack traceback:
[C]: in function 'kumo.on'
[string "simple_policy.lua"]:232: in main chunk
caused by: smtp_server_auth_plain event already has a handler defined at simple_policy.lua:226
```
This is a pretty tight, lightweight implementation of SOCKS5
intended to be used to facilitate an MTA asking it to bind and
connect.
It uses the splice(2) syscall to avoid kernel/userspace copies
when passing data through, so it should be quite efficient.
refs: https://github.com/KumoCorp/kumomta/issues/45
Wez Furlong
Tom Mairs
Mike Hillyer