Net::IMAP::Server - A single-threaded multiplexing IMAP server implementation, using Net::Server::Coro.

  use Net::IMAP::Server;
  Net::IMAP::Server->new(
      port        => 193,
      ssl_port    => 993,
      auth_class  => "Your::Auth::Class",
      model_class => "Your::Model::Class",
      user        => "nobody",
      group       => "nobody",
  )->run;

This model provides a complete implementation of the RFC 3501 specification, along with several IMAP4rev1 extensions. It provides separation of the mailbox and message store from the client interaction loop.

Note that, following RFC suggestions, login is not allowed except under a either SSL or TLS. Thus, you are required to have a certs/ directory under the current working directory, containing files server-cert.pem and server-key.pem. Failure to do so will cause the server to fail to start. Note that if the default paths suit your needs, you can specify different ones using the server_cert and server_key arguments to new.

The primary method of using this module is to supply your own model and auth classes, which inherit from Net::IMAP::Server::DefaultModel and Net::IMAP::Server::DefaultAuth. This allows you to back your messages from arbitrary data sources, or provide your own authorization backend. For the most part, the implementation of the IMAP components should be opaque.

Creates a new IMAP server object. This doesn't even bind to the sockets; it merely initializes the object. It will die if it cannot find the appropriate certificate files. Valid arguments to new include:

port

The port to bind to. Defaults to port 1430.

ssl_port

The port to open an SSL listener on; by default, this is disabled, and any true value enables it.

auth_class

The name of the class which implements authentication. This must be a subclass of Net::IMAP::Server::DefaultAuth.

model_class

The name of the class which implements the model backend. This must be a subclass of Net::IMAP::Server::DefaultModel.

connection_class

On rare occasions, you may wish to subclass the connection class; this class must be a subclass of Net::IMAP::Server::Connection.

poll_every

How often the current mailbox should be polled, in seconds; defaults to 0, which means it will be polled after every client command.

unauth_commands

The number of commands before unauthenticated users are disconnected. The default is 10; set to zero to disable.

unauth_idle

How long, in seconds, to wait before disconnecting idle connections which have not authenticated yet. The default is 5 minutes; set to zero to disable (which is not advised).

auth_idle

How long, in seconds, to wait before disconnecting authenticated connections. By RFC specification, this must be longer than 30 minutes. The default is an hour; set to zero to disable.

server_cert

Path to the SSL certificate that the server should use. This can be either a relative or absolute path.

server_key

Path to the SSL certificate key that the server should use. This can be either a relative or absolute path.

It also accepts the following Net::Server arguments -- see its documentation for details on their use.

log_level in Net::Server

log_file in Net::Server

syslog_logsock in Net::Server

syslog_ident in Net::Server

syslog_logopt in Net::Server

syslog_facility in Net::Server

pid_file in Net::Server

chroot in Net::Server

user in Net::Server

group in Net::Server

reverse_lookups in Net::Server

allow in Net::Server

deny in Net::Server

cidr_allow in Net::Server

cidr_deny in Net::Server

Starts the server; this method shouldn't be expected to return. Within this method, $Net::IMAP::Server::Server is set to the object that this was called on; thus, all IMAP objects have a way of referring to the server -- and though connection, whatever parts of the IMAP internals they need.

Any arguments are passed through to run in Net::Server.

Accepts a client connection; this method is needed for the Net::Server infrastructure.

On destruction, ensure that we close all client connections and listening sockets.

Returns an arrayref of Net::IMAP::Server::Connection objects which are currently connected to the server.

Returns the currently active Net::IMAP::Server::Connection object, if there is one. This is determined by examining the current coroutine.

This can be called as either a class method or an instance method; it returns the set of connections which are concurrently connected to the given mailbox object (which defaults to the current connection's selected mailbox)

This can be called as either a class method or an instance method; it returns the set of connections whose user in Net::IMAP::Server::DefaultAuth is the same as the given USER (which defaults to the current connection's user)

Returns the CAPABILITY string for the server. This string my be modified by the connection before being sent to the client (see capability in Net::IMAP::Server::Connection).

Returns a hash of properties to be conveyed to the client, should they ask the server's identity.

Adds the given command NAME to the server's list of known commands. PACKAGE should be the name of a class which inherits from Net::IMAP::Server::Command.

By default, defers to log in Net::Server, which outputs to syslog, a logfile, or STDERR, depending how it was configured. Net::Server's default is to print to STDERR. If you have custom logging needs, override this method, or write_to_log_hook in Net::Server.

An ASCII model of the relationship between objects is below. In it, single lines represent scalar values, and lines made of other characters denote array references or relations.

   +----------------------------------------------+
   |                                              |
   |                    Server                    |
   |                                              |
   +1-----2---------------------------------------+
    #     '      ^         ^            ^        ^
    #     '      |         |            |        |
    #     v      |         |            |        |
    #   +--------1-------+ |     +------1------+ |
    ###>|   Connection   |<------2   Command   | |
    #   +--4-----3------2+ |     +-------------+ |
  /-#------/     |      \--------------\         |
  | #            v         |           v         |
  | #   +----------------+ |     +-------------+ |
  | #   |     Model      2------>|    Auth     | |
  | #   +--------1-------+ |     +-------------+ |
  | #            \---------------------------------\
  | #                      |                     | |
  | #                  /---/                 /---/ |
  | #   +--------------1-+       +-----------1-+   |
  | ###>|   Connection   |<------2   Command   |   |
  |     +--4-5---3------2+       +-------------+   |
  | /------/ *   |      \--------------\           |
  | | ********   v                     v           |
  | | * +----------------+       +-------------+   |
  | | * |     Model      2------>|    Auth     |   |
  | | * +--------1-------+       +-------------+   |
  | | *          |                                 |
  | | *          |  /------------------------------/
  | | *          |  |           ^ SERVER
  |.|.*..........|..|................................
  | | *          |  |           v MODEL
  | | *          v  v
  | \-*---->+-------------+<------------\
  \---*---->|   Mailbox   |<----------\ |
      *     +-1------2-3--+<----\     | |
      *       @   ^  $ %        |     | |
      *       @   |  $$%$>+-----1---+ | |
      *       @   |  $ %%>| Message | | |
      ********@***|****%*>+---------+ | |
      *       @   |  $ %              | |
      *       @   |  $$%$>+---------+ | |
      *       @   |    %%>| Message 1-/ |
      ********@***|******>+---------+   |
      *       @   |                     |
      *       @   |       +---------+   |
      *       @   |       | Message 1---/
      ********@***|******>+---------+
              @   |
              @  +4----------+
              @@>|  Mailbox  |
                 +-----------+

The top half consists of the parts which implement the IMAP protocol itself; the bottom contains the models for the backing store. Note that, for the most part, the backing store is unaware of the framework of the server itself.

Each model has references to others, as follows:

Server

Contains references to the set of connections (1). It also has a sense of the current connection (2), based on the active Coro thread.

Connection

Connections hold a reference to their server (1). If the connection has authenticated, they hold a reference to the auth object (2), and to their model (3). If a mailbox is selected (4), they hold a pointer to that, as well. Infrequently, the connection will need to temporarily store references to the set of temporary_messages (5) which have been expunged in other connections, but we have been unable to notify this connection of.

Command

Commands store their server (1) and connection (2).

Model

Models store a reference to the root (1) of their mailbox tree, as well as to the auth (2) which gives them access to such.

Mailbox

Mailboxes store a list of children mailboxes (1), and messages (2) contained within them, which are stored in sequence order. They also contain a hash of uids (3) for fast UID retrieval of messages. If they are not the root mailbox, they also store a reference to their parent mailbox (4).

Message

Messages store the mailbox (1) in which they are contained.

Coro, Net::Server::Coro

No bugs have been reported.

Please report any bugs or feature requests to bug-net-imap-server@rt.cpan.org, or through the web interface at http://rt.cpan.org.

A low-traffic mailing list exists for discussion on how to (ab)use this module, at http://lists.bestpractical.com/cgi-bin/mailman/listinfo/net-imap-server.

Alex Vandiver <alexmv@bestpractical.com>

Copyright (c) 2010, Best Practical Solutions, LLC. All rights reserved.

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