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New IMAP filter/proxy release: guam 0.8, eimap 0.2


New IMAP filter/proxy release: guam 0.8, eimap 0.2

Over the last few months I have been poking away at a refactoring of the IMAP library that Kolab's IMAP filter/proxy uses behind the scenes, called eimap. It consolidated quite a bit of duplicated code between the various IMAP commands that are supported, and fixed a few bugs along the way. This refactoring dropped the code count, makes implementing new commands even easier, and has allowed for improvements that affect all commands (usually because they are related to the core IMAP protocol) to be made in one central place. This was rolled as eimap 0.2 the other week and has made its way through the packaging process for Kolab. This is a significant milestone for eimap on the path to being able to be considered "stable".

Guam 0.8 was tagged last week and takes full advantage of eimap 0.2. This has entered the packaging phase now, but you can grab guam 0.8 here:

Highlights of these two releases include:

  • EIMAP
    • several new IMAP commands supported
    • all core IMAP response handling is centralized, making the implementation for each command significantly simpler and more consistent
    • support for multi-line, single-line and binary response command types
    • support for literals continuation
    • improved TLS support
    • fixes for metadata fetching
    • support for automated interruption of passthrough state to send structured commands
    • commands receive server responses for commands they put into the queue
  • Guam
    • ported to eimap 0.2
    • limit processcommandqueue messages in the FSM's mailbox to one in the per-session state machine
    • be more expansive in what is supported in LIST commands for the groupware folder filter rule
    • init scripts for both sysv and systemd

One change that did not make it into 0.8 was the ability to define which port to bind guam listeners to by network interface. This is already merged for 0.9, however. I also received from interest in using Guam with other IMAP servers, so it looks likely that guam 0.8 will get testing with Dovecot in addition to Cyrus.

Caveats: If you are building by hand using the included rebar build, you may run into some issues with the lager dependencies, depending on what versions of lager and friends are installed globally (if any). If so, change the dependencies in rebar.config to match what is installed. This is largely down to rebar 2.x being a little limited in its ability to handle such things. We are moving to rebar3 for all the erlang packages, so eimap 0.3 and guam 0.9 will both use rebar3. I have guam already building with rebar3 in a 0.9 feature branch, and it was pretty painless and produces something even a little nicer already. As soon as I fix up the release generation, this will probably be the first feature branch to land in the develop branch of guam for 0.9!

It is also known that the test suite for Guam 0.8 is broken. I have this building and working again in the 0.9 branch, and will probably be doing some significant changes to how these tests are run for 0.9.

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