Push Notification Framework

Introduction

Dovecot’s Push Notification framework exposes RFC 5423 (Internet Message Store Events) events that occur in Dovecot to a system that can be used to report these events to external services.

These events are available within the notification framework, although a driver may not implement all:

  • FlagsClear
  • FlagsSet
  • MailboxCreate
  • MailboxDelete
  • MailboxRename
  • MailboxSubscribe
  • MailboxUnsubscribe
  • MessageAppend
  • MessageExpunge
  • MessageNew
  • MessageRead
  • MessageTrash

These events are not supported by the notification framework:

Usage

To use push notifications, both the notify and the push_notification plugins need to be activated. For LMTP delivery, this is required:

protocol lmtp {
  mail_plugins = $mail_plugins notify push_notification
}

If you also want push notifications to work for LDA-based delivery, you would need additional configuration:

protocol lda {
  mail_plugins = $mail_plugins notify push_notification
}

Drivers

DLOG (Debug log)

plugin {
  push_notification_driver = dlog
}

This will cause notifications to end up in your debug log.

OX (Open-Xchange) driver

The OX backend supports sending notifications on MessageNew events (i.e. mail deliveries, not IMAP APPENDs).

The HTTP end-point (URL + authentication information) to use is configured in the Dovecot configuration file. The appropriate configuration options will contain the HTTP URL denoting the end-point to connect to as well as the authentication information for Basic Authentication as configured by properties com.openexchange.rest.services.basic-auth.login and com.openexchange.rest.services.basic-auth.password. The URL to configure in Dovecot configuration follows this pattern.

<http|https> + "://" + <login> + ":" + <password> + "@" + <host> + ":" + <port> + "/preliminary/http-notify/v1/notify"

E.g.

plugin {
  push_notification_driver = ox:url=http://login:pass@node1.domain.tld:8009/preliminary/http-notify/v1/notify
}

For HTTPS endpoints, system CAs are trusted by default, but internal CAs might need further configuration.

Furthermore, it is also possible to specify more than one HTTP end-point to connect to if a new message delivery occurs. Thus the configuration section mentioned above may be extended by additional push_notification_driver entries; e.g. push_notification_driver2, push_notification_driver3, etc.

Please note that the path /preliminary/http-notify/v1/notify denotes the internal REST API of the Open-Xchange Middleware, which is not publicly accessible. The administrator can decide whether to add that path to the Apache configuration (see also AppSuite:Apache_Configuration and AppSuite:Grizzly) through a Location/ProxyPass directive:

<Location /preliminary>
  Order Deny,Allow
  Deny from all
  # Only allow access from servers within the network. Do not expose this
  # location outside of your network. In case you use a load balancing service in front
  # of your Apache infrastructure you should make sure that access to /preliminary will
  # be blocked from the internet / outside clients. Examples:
  # Allow from 192.168.0.1
  # Allow from 192.168.1.1 192.168.1.2
  # Allow from 192.168.0.
  ProxyPass /preliminary balancer://oxcluster/preliminary
</Location>

In case the user= sent by OX in the push_notification_driver url data does not match the IMAP login of a user, Dovecot ignores it. This can be overridden by defining user_from_metadata in the push_notification_driver url, e.g.

push_notification_driver = ox:url=http://example.com/ user_from_metadata

Metadata

The push notifications are enabled separately for each user using METADATA. Normally AppSuite does this internally, but for e.g. testing purposes you can do this yourself:

doveadm mailbox metadata set -u user@example.com -s "" /private/vendor/vendor.dovecot/http-notify user=11@3

Example Payload

See https://github.com/dovecot/core/blob/master/src/plugins/push-notification/push-notification-driver-ox.c.

Push notification sent in JSON format with the following fields:

  • user: User identifier (string)
  • event: RFC 5423 event type (string; currently only “MessageNew”)
  • folder: Mailbox name (string)
  • imap-uidvalidity: RFC 3501 UIDVALIDITY value of the mailbox (integer)
  • imap-uid: UID of the message, if applicable (integer)
  • from: RFC 2822 address of the message sender, if applicable (string)
  • subject: Subject of the message, if applicable (string)
  • snippet: Snippet of the message body, if applicable (string)
  • unseen: RFC 3501 UNSEEN value of the mailbox (integer)
Content-Type: application/json; charset=utf-8

{
  "user": "4@464646669",
  "imap-uidvalidity": 123412341,
  "imap-uid": 2345,
  "folder": "INBOX",
  "event": "MessageNew",
  "from": "alice@barfoo.org",
  "subject": "Test",
  "snippet": "Hey guys\nThis is only a test...",
  "unseen": 2
}

Lua

New in version v2.3.4.

You can use Lua to write custom push notification handlers. See Design/Lua for general information about Lua in Dovecot. If you have mail_lua_script (a global script for storage) it will be used if no script is specified.

Configuration

mail_plugins = $mail_plugins mail_lua notify push_notification push_notification_lua

plugin {
  push_notification_driver = lua:file=/path/to/lua/script
  # you can omit the script name if you want to use mail_lua_script script instead
  #mail_lua_script=/path/to/common/script.lua
}

Example script

Simple example

1  -- To use
2  --
3  -- plugin {
4  --  push_notification_driver = lua:file=/home/cmouse/empty.lua
5  --  push_lua_url = http://push.notification.server/handler
6  -- }
7  --
8  -- server is sent a POST message to given url with parameters
9  --
10
11 local http = require("socket.http")
12 local url = require("socket.url")
13
14 function table_get(t, k, d)
15   return t[k] or d
16 end
17
18 function dovecot_lua_notify_begin_txn(user)
19   return {messages={}, ep=user:plugin_getenv("push_lua_url"), username=user.username}
20 end
21
22 function dovecot_lua_notify_end_txn(ctx, success)
23   local i, msg = next(ctx["messages"], nil)
24   while i do
25     local r, c = http.request(ctx["ep"], "from=" .. url.escape(table_get(msg, "from", "")) .. "&to=" .. url.escape(table_get(msg, "to", "")) .. "&subject=" .. url.escape(table_get(msg, "subject", "")) .. "&snippet=" .. url.escape(table_get(msg, "snippet", "")) .. "&user=" .. url.escape(ctx["username"]))
26     if r and c/100 ~= 2 then
27       dovecot.i_error("lua-push: Remote error " .. tostring(c) .. " handling push notication")
28     end
29     if r == nil then
30       dovecot.i_error("lua-push: " .. c)
31     end
32     i, msg = next(ctx["messages"], i)
33   end
34 end
35
36 function dovecot_lua_notify_event_message_append(ctx, event)
37   table.insert(ctx["messages"], event)
38 end
39
40 function dovecot_lua_notify_event_message_new(ctx, event)
41   table.insert(ctx["messages"], event)
42 end

New in version v2.3.4.

Example with event code

1  -- To use
2  --
3  -- plugin {
4  --  push_notification_driver = lua:file=/home/cmouse/empty.lua
5  --  push_lua_url = http://push.notification.server/handler
6  -- }
7  --
8  -- server is sent a POST message to given url with parameters
9  --
10
11 local http = require "socket.http"
12 local ltn12 = require "ltn12"
13 local url = require "socket.url"
14
15 function table_get(t, k, d)
16   return t[k] or d
17 end
18
19 function script_init()
20   return 0
21 end
22
23 function dovecot_lua_notify_begin_txn(user)
24   return {user=user, event=dovecot.event(), ep=user:plugin_getenv("push_lua_url"), states={}, messages={}}
25 end
26
27 function dovecot_lua_notify_event_message_new(ctx, event)
28   -- get mailbox status
29   local mbox = ctx.user:mailbox(event.mailbox)
30   mbox:sync()
31   local status = mbox:status(dovecot.storage.STATUS_RECENT, dovecot.storage.STATUS_UNSEEN, dovecot.storage.STATUS_MESSAGES)
32   mbox:free()
33   ctx.states[event.mailbox] = status
34   table.insert(ctx.messages, {from=event.from,subject=event.subject,mailbox=event.mailbox})
35 end
36
37 function dovecot_lua_notify_event_message_append(ctx, event, user)
38   dovecot_lua_notify_event_message_new(ctx, event, user)
39 end
40
41 function dovecot_lua_notify_end_txn(ctx)
42   -- report all states
43   for i,msg in ipairs(ctx.messages) do
44     local e = dovecot.event(ctx.event)
45     e:set_name("lua_notify_mail_finished")
46     reqbody = "mailbox=" .. url.escape(msg.mailbox) .. "&from=" .. url.escape(table_get(msg, "from", "")) .. "&subject=" .. url.escape(table_get(msg, "subject", ""))
47     e:log_debug(ctx.ep .. " - sending " .. reqbody)
48     res, code = http.request({method="POST",
49                   url=ctx.ep,
50                   source=ltn12.source.string(reqbody),
51                   headers={
52                     ["content-type"] = "application/x-www-form-url.escaped",
53                     ["content-length"] = tostring(#reqbody)
54                   }
55                  })
56     e:add_int("result_code", code)
57     e:log_info("Mail notify status " .. tostring(code))
58   end
59   for box,state in pairs(ctx.states) do
60     local e = dovecot.event()
61     e:set_name("lua_notify_mailbox_finished")
62     reqbody = "mailbox=" .. url.escape(state.mailbox) .. "&recent=" .. tostring(state.recent) .. "&unseen=" .. tostring(state.unseen) .. "&messages=" .. tostring(state.messages)
63     e:log_debug(ctx.ep .. " - sending " .. reqbody)
64     res, code = http.request({method="POST",
65                   url=ctx.ep,
66                   source=ltn12.source.string(reqbody),
67                   headers={
68                     ["content-type"] = "application/x-www-form-url.escaped",
69                     ["content-length"] = tostring(#reqbody)
70                   }
71                  })
72     e:add_int("result_code", code)
73     e:log_info("Mailbox notify status " .. tostring(code))
74   end
75 end

Overview

The Lua driver hooks into all events, and calls matching functions when found in Lua script.

Currently it supports

  • mailbox create, delete, rename, subscribe and unsubscribe
  • message new, append, expunge, read and trash, flags set, flags clear

All events are called within a transaction. The event is called with context and an event table, which contains the event parameters. All events contain at least

  • name - name of the event
  • user - current mail user

Events are always called after the fact.

There has to be at least one event handler, or the transaction begin and end functions are never called. This is optimization to avoid roundtrip to Lua when it’s not needed.

Transactions

  • dovecot_lua_notify_begin_txn(user)

Start transaction. Return value is used as transaction context and is treated as opaque value by Lua driver. The user parameter is mail_user object.

  • dovecot_lua_notify_end_txn(context, success)

End transaction, context is unreferenced.

Mailbox events

All mailbox events contain mailbox parameter, which is the name of the affected mailbox.

  • dovecot_lua_notify_event_mailbox_create(context, {name, mailbox})

Called when mailbox has been created.

  • dovecot_lua_notify_event_mailbox_delete(context, {name, mailbox})

Called when mailbox has been deleted.

  • dovecot_lua_notify_event_mailbox_rename(context, {name, mailbox, mailbox_old})

Called when mailbox has been renamed, old name is retained in mailbox_old attribute.

  • dovecot_lua_notify_event_mailbox_subscribe(context, {name, mailbox})

Called when mailbox has been subscribed to. The mailbox does not necessarily exist.

  • dovecot_lua_notify_event_mailbox_unsubscribe(context, {name, mailbox})

Called when mailbox has been unsubscribed from. The mailbox does not necessarily exist.

Message events

All message events contain following parameters

mailbox Mailbox name
uid Message UID
uid_validity Mailbox UID validity
  • dovecot_lua_notify_event_message_new(context, {name, mailbox, uid, uid_validity, date, tz, from, to, subject, snippet})

Called when message is delivered.

  • dovecot_lua_notify_event_message_append(context, {name, mailbox, uid, uid_validity, from, to, subject, snippet})

Called when message is APPENDed to a mailbox.

  • dovecot_lua_notify_event_message_read(context, {name, mailbox, uid, uid_validity})

Called when message is marked as Seen.

  • dovecot_lua_notify_event_message_trash(context, {name, mailbox, uid, uid_validity})

Called when message is marked Deleted.

  • dovecot_lua_notify_event_message_expunge(context, {name, mailbox, uid, uid_validity})

Called when message is EXPUNGEd.

  • dovecot_lua_notify_event_flags_set(context, {name, mailbox, uid, uid_validity, flags, keywords_set})

Called when message flags or keywords are set. flags is a bitmask. keywords_set is a table of strings of the keywords set by the event.

  • dovecot_lua_notify_event_flags_clear(context, {name, mailbox, uid, uid_validity, flags, keywords_clear, keywords_old})

Called when message flags or keywords are removed. flags is a bitmask. keywords_clear contains the keywords cleared, keywords_old is the table of keywords that were set before the event.