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imap.rb
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# frozen_string_literal: true
#
# = net/imap.rb
#
# Copyright (C) 2000 Shugo Maeda <shugo@ruby-lang.org>
#
# This library is distributed under the terms of the Ruby license.
# You can freely distribute/modify this library.
#
# Documentation: Shugo Maeda, with RDoc conversion and overview by William
# Webber.
#
# See Net::IMAP for documentation.
#
require "socket"
require "monitor"
require 'net/protocol'
begin
require "openssl"
rescue LoadError
end
module Net
# Net::IMAP implements Internet Message Access Protocol (\IMAP) client
# functionality. The protocol is described in
# [IMAP4rev1[https://tools.ietf.org/html/rfc3501]].
#--
# TODO: and [IMAP4rev2[https://tools.ietf.org/html/rfc9051]].
#++
#
# == \IMAP Overview
#
# An \IMAP client connects to a server, and then authenticates
# itself using either #authenticate or #login. Having
# authenticated itself, there is a range of commands
# available to it. Most work with mailboxes, which may be
# arranged in an hierarchical namespace, and each of which
# contains zero or more messages. How this is implemented on
# the server is implementation-dependent; on a UNIX server, it
# will frequently be implemented as files in mailbox format
# within a hierarchy of directories.
#
# To work on the messages within a mailbox, the client must
# first select that mailbox, using either #select or #examine
# (for read-only access). Once the client has successfully
# selected a mailbox, they enter the "_selected_" state, and that
# mailbox becomes the _current_ mailbox, on which mail-item
# related commands implicitly operate.
#
# === Sequence numbers and UIDs
#
# Messages have two sorts of identifiers: message sequence
# numbers and UIDs.
#
# Message sequence numbers number messages within a mailbox
# from 1 up to the number of items in the mailbox. If a new
# message arrives during a session, it receives a sequence
# number equal to the new size of the mailbox. If messages
# are expunged from the mailbox, remaining messages have their
# sequence numbers "shuffled down" to fill the gaps.
#
# To avoid sequence number race conditions, servers must not expunge messages
# when no command is in progress, nor when responding to #fetch, #store, or
# #search. Expunges _may_ be sent during any other command, including
# #uid_fetch, #uid_store, and #uid_search. The #noop and #idle commands are
# both useful for this side-effect: they allow the server to send all mailbox
# updates, including expunges.
#
# UIDs, on the other hand, are permanently guaranteed not to
# identify another message within the same mailbox, even if
# the existing message is deleted. UIDs are required to
# be assigned in ascending (but not necessarily sequential)
# order within a mailbox; this means that if a non-IMAP client
# rearranges the order of mail items within a mailbox, the
# UIDs have to be reassigned. An \IMAP client thus cannot
# rearrange message orders.
#
# === Server capabilities and protocol extensions
#
# Net::IMAP <em>does not modify its behavior</em> according to server
# #capability. Users of the class must check for required capabilities before
# issuing commands. Special care should be taken to follow all #capability
# requirements for #starttls, #login, and #authenticate.
#
# See the #capability method for more information.
#
# == Examples of Usage
#
# === List sender and subject of all recent messages in the default mailbox
#
# imap = Net::IMAP.new('mail.example.com')
# imap.authenticate('LOGIN', 'joe_user', 'joes_password')
# imap.examine('INBOX')
# imap.search(["RECENT"]).each do |message_id|
# envelope = imap.fetch(message_id, "ENVELOPE")[0].attr["ENVELOPE"]
# puts "#{envelope.from[0].name}: \t#{envelope.subject}"
# end
#
# === Move all messages from April 2003 from "Mail/sent-mail" to "Mail/sent-apr03"
#
# imap = Net::IMAP.new('mail.example.com')
# imap.authenticate('LOGIN', 'joe_user', 'joes_password')
# imap.select('Mail/sent-mail')
# if not imap.list('Mail/', 'sent-apr03')
# imap.create('Mail/sent-apr03')
# end
# imap.search(["BEFORE", "30-Apr-2003", "SINCE", "1-Apr-2003"]).each do |message_id|
# imap.copy(message_id, "Mail/sent-apr03")
# imap.store(message_id, "+FLAGS", [:Deleted])
# end
# imap.expunge
#
# == Thread Safety
#
# Net::IMAP supports concurrent threads. For example,
#
# imap = Net::IMAP.new("imap.foo.net", "imap2")
# imap.authenticate("cram-md5", "bar", "password")
# imap.select("inbox")
# fetch_thread = Thread.start { imap.fetch(1..-1, "UID") }
# search_result = imap.search(["BODY", "hello"])
# fetch_result = fetch_thread.value
# imap.disconnect
#
# This script invokes the FETCH command and the SEARCH command concurrently.
#
# == Errors
#
# An \IMAP server can send three different types of responses to indicate
# failure:
#
# NO:: the attempted command could not be successfully completed. For
# instance, the username/password used for logging in are incorrect;
# the selected mailbox does not exist; etc.
#
# BAD:: the request from the client does not follow the server's
# understanding of the \IMAP protocol. This includes attempting
# commands from the wrong client state; for instance, attempting
# to perform a SEARCH command without having SELECTed a current
# mailbox. It can also signal an internal server
# failure (such as a disk crash) has occurred.
#
# BYE:: the server is saying goodbye. This can be part of a normal
# logout sequence, and can be used as part of a login sequence
# to indicate that the server is (for some reason) unwilling
# to accept your connection. As a response to any other command,
# it indicates either that the server is shutting down, or that
# the server is timing out the client connection due to inactivity.
#
# These three error response are represented by the errors
# Net::IMAP::NoResponseError, Net::IMAP::BadResponseError, and
# Net::IMAP::ByeResponseError, all of which are subclasses of
# Net::IMAP::ResponseError. Essentially, all methods that involve
# sending a request to the server can generate one of these errors.
# Only the most pertinent instances have been documented below.
#
# Because the IMAP class uses Sockets for communication, its methods
# are also susceptible to the various errors that can occur when
# working with sockets. These are generally represented as
# Errno errors. For instance, any method that involves sending a
# request to the server and/or receiving a response from it could
# raise an Errno::EPIPE error if the network connection unexpectedly
# goes down. See the socket(7), ip(7), tcp(7), socket(2), connect(2),
# and associated man pages.
#
# Finally, a Net::IMAP::DataFormatError is thrown if low-level data
# is found to be in an incorrect format (for instance, when converting
# between UTF-8 and UTF-16), and Net::IMAP::ResponseParseError is
# thrown if a server response is non-parseable.
#
# == What's here?
#
# * {Connection control}[rdoc-ref:Net::IMAP@Connection+control+methods]
# * {Core IMAP commands}[rdoc-ref:Net::IMAP@Core+IMAP+commands]
# * {...for any state}[rdoc-ref:Net::IMAP@IMAP+commands+for+any+state]
# * {...for the "not authenticated" state}[rdoc-ref:Net::IMAP@IMAP+commands+for+the+-22Not+Authenticated-22+state]
# * {...for the "authenticated" state}[rdoc-ref:Net::IMAP@IMAP+commands+for+the+-22Authenticated-22+state]
# * {...for the "selected" state}[rdoc-ref:Net::IMAP@IMAP+commands+for+the+-22Selected-22+state]
# * {...for the "logout" state}[rdoc-ref:Net::IMAP@IMAP+commands+for+the+-22Logout-22+state]
# * {Supported IMAP extensions}[rdoc-ref:Net::IMAP@Supported+IMAP+extensions]
# * {Handling server responses}[rdoc-ref:Net::IMAP@Handling+server+responses]
#
# === Connection control methods
#
# - Net::IMAP.new: A new client connects immediately and waits for a
# successful server greeting before returning the new client object.
# - #starttls: Asks the server to upgrade a clear-text connection to use TLS.
# - #logout: Tells the server to end the session. Enters the "_logout_" state.
# - #disconnect: Disconnects the connection (without sending #logout first).
# - #disconnected?: True if the connection has been closed.
#
# === Core \IMAP commands
#
# The following commands are defined either by
# the [IMAP4rev1[https://tools.ietf.org/html/rfc3501]] base specification, or
# by one of the following extensions:
# [IDLE[https://tools.ietf.org/html/rfc2177]],
# [NAMESPACE[https://tools.ietf.org/html/rfc2342]],
# [UNSELECT[https://tools.ietf.org/html/rfc3691]],
#--
# TODO: [ENABLE[https://tools.ietf.org/html/rfc5161]],
# TODO: [LIST-EXTENDED[https://tools.ietf.org/html/rfc5258]],
# TODO: [LIST-STATUS[https://tools.ietf.org/html/rfc5819]],
#++
# [MOVE[https://tools.ietf.org/html/rfc6851]].
# These extensions are widely supported by modern IMAP4rev1 servers and have
# all been integrated into [IMAP4rev2[https://tools.ietf.org/html/rfc9051]].
# <em>Note: Net::IMAP doesn't fully support IMAP4rev2 yet.</em>
#
#--
# TODO: When IMAP4rev2 is supported, add the following to the each of the
# appropriate commands below.
# Note:: CHECK has been removed from IMAP4rev2.
# Note:: LSUB is obsoleted by +LIST-EXTENDED and has been removed from IMAP4rev2.
# <em>Some arguments require the +LIST-EXTENDED+ or +IMAP4rev2+ capability.</em>
# <em>Requires either the +ENABLE+ or +IMAP4rev2+ capability.</em>
# <em>Requires either the +NAMESPACE+ or +IMAP4rev2+ capability.</em>
# <em>Requires either the +IDLE+ or +IMAP4rev2+ capability.</em>
# <em>Requires either the +UNSELECT+ or +IMAP4rev2+ capability.</em>
# <em>Requires either the +UIDPLUS+ or +IMAP4rev2+ capability.</em>
# <em>Requires either the +MOVE+ or +IMAP4rev2+ capability.</em>
#++
#
# ==== \IMAP commands for any state
#
# - #capability: Returns the server's capabilities as an array of strings.
#
# <em>Capabilities may change after</em> #starttls, #authenticate, or #login
# <em>and cached capabilities must be reloaded.</em>
# - #noop: Allows the server to send unsolicited untagged #responses.
# - #logout: Tells the server to end the session. Enters the "_logout_" state.
#
# ==== \IMAP commands for the "Not Authenticated" state
#
# In addition to the universal commands, the following commands are valid in
# the "<em>not authenticated</em>" state:
#
# - #starttls: Upgrades a clear-text connection to use TLS.
#
# <em>Requires the +STARTTLS+ capability.</em>
# - #authenticate: Identifies the client to the server using a {SASL
# mechanism}[https://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml].
# Enters the "_authenticated_" state.
#
# <em>Requires the <tt>AUTH=#{mechanism}</tt> capability for the chosen
# mechanism.</em>
# - #login: Identifies the client to the server using a plain text password.
# Using #authenticate is generally preferred. Enters the "_authenticated_"
# state.
#
# <em>The +LOGINDISABLED+ capability</em> <b>must NOT</b> <em>be listed.</em>
#
# ==== \IMAP commands for the "Authenticated" state
#
# In addition to the universal commands, the following commands are valid in
# the "_authenticated_" state:
#
#--
# - #enable: <em>Not implemented by Net::IMAP, yet.</em>
#
# <em>Requires the +ENABLE+ capability.</em>
#++
# - #select: Open a mailbox and enter the "_selected_" state.
# - #examine: Open a mailbox read-only, and enter the "_selected_" state.
# - #create: Creates a new mailbox.
# - #delete: Permanently remove a mailbox.
# - #rename: Change the name of a mailbox.
# - #subscribe: Adds a mailbox to the "subscribed" set.
# - #unsubscribe: Removes a mailbox from the "subscribed" set.
# - #list: Returns names and attributes of mailboxes matching a given pattern.
# - #namespace: Returns mailbox namespaces, with path prefixes and delimiters.
#
# <em>Requires the +NAMESPACE+ capability.</em>
# - #status: Returns mailbox information, e.g. message count, unseen message
# count, +UIDVALIDITY+ and +UIDNEXT+.
# - #append: Appends a message to the end of a mailbox.
# - #idle: Allows the server to send updates to the client, without the client
# needing to poll using #noop.
#
# <em>Requires the +IDLE+ capability.</em>
# - #lsub: Lists mailboxes the user has declared "active" or "subscribed".
#--
# <em>Replaced by</em> <tt>LIST-EXTENDED</tt> <em>and removed from</em>
# +IMAP4rev2+. <em>However, Net::IMAP hasn't implemented</em>
# <tt>LIST-EXTENDED</tt> _yet_.
#++
#
# ==== \IMAP commands for the "Selected" state
#
# In addition to the universal commands and the "authenticated" commands, the
# following commands are valid in the "_selected_" state:
#
# - #close: Closes the mailbox and returns to the "_authenticated_" state,
# expunging deleted messages, unless the mailbox was opened as read-only.
# - #unselect: Closes the mailbox and returns to the "_authenticated_" state,
# without expunging any messages.
#
# <em>Requires the +UNSELECT+ capability.</em>
# - #expunge: Permanently removes messages which have the Deleted flag set.
# - #uid_expunge: Restricts #expunge to only remove the specified UIDs.
#
# <em>Requires the +UIDPLUS+ capability.</em>
# - #search, #uid_search: Returns sequence numbers or UIDs of messages that
# match the given searching criteria.
# - #fetch, #uid_fetch: Returns data associated with a set of messages,
# specified by sequence number or UID.
# - #store, #uid_store: Alters a message's flags.
# - #copy, #uid_copy: Copies the specified messages to the end of the
# specified destination mailbox.
# - #move, #uid_move: Moves the specified messages to the end of the
# specified destination mailbox, expunging them from the current mailbox.
#
# <em>Requires the +MOVE+ capability.</em>
# - #check: Mostly obsolete. Can be replaced with #noop or #idle.
#--
# <em>Removed from IMAP4rev2.</em>
#++
#
# ==== \IMAP commands for the "Logout" state
#
# No \IMAP commands are valid in the +logout+ state. If the socket is still
# open, Net::IMAP will close it after receiving server confirmation.
# Exceptions will be raised by \IMAP commands that have already started and
# are waiting for a response, as well as any that are called after logout.
#
# === Supported \IMAP extensions
#
# ==== RFC9051: +IMAP4rev2+
#
# Although IMAP4rev2[https://tools.ietf.org/html/rfc9051] is <em>not supported
# yet</em>, Net::IMAP supports several extensions that have been folded into
# it: +IDLE+, +MOVE+, +NAMESPACE+, +UIDPLUS+, and +UNSELECT+.
#--
# TODO: RFC4466, ABNF extensions (automatic support for other extensions)
# TODO: +ESEARCH+, ExtendedSearchData
# TODO: +SEARCHRES+,
# TODO: +ENABLE+,
# TODO: +SASL-IR+,
# TODO: +LIST-EXTENDED+,
# TODO: +LIST-STATUS+,
# TODO: +LITERAL-+,
# TODO: +BINARY+ (only the FETCH side)
# TODO: +SPECIAL-USE+
# implicitly supported, but we can do better: Response codes: RFC5530, etc
# implicitly supported, but we can do better: <tt>STATUS=SIZE</tt>
# implicitly supported, but we can do better: <tt>STATUS DELETED</tt>
#++
# Commands for these extensions are included with the {Core IMAP
# commands}[rdoc-ref:Net::IMAP@Core+IMAP+commands], above. Other supported
# extensons are listed below.
#
# ==== RFC2087: +QUOTA+
# - #getquota: returns the resource usage and limits for a quota root
# - #getquotaroot: returns the list of quota roots for a mailbox, as well as
# their resource usage and limits.
# - #setquota: sets the resource limits for a given quota root.
#
# ==== RFC2177: +IDLE+
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051], so it is also
# listed with {Core IMAP commands}[rdoc-ref:Net::IMAP@Core+IMAP+commands].
# - #idle: Allows the server to send updates to the client, without the client
# needing to poll using #noop.
#
# ==== RFC2342: +NAMESPACE+
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051], so it is also
# listed with {Core IMAP commands}[rdoc-ref:Net::IMAP@Core+IMAP+commands].
# - #namespace: Returns mailbox namespaces, with path prefixes and delimiters.
#
# ==== RFC2971: +ID+
# - #id: exchanges client and server implementation information.
#
#--
# ==== RFC3502: +MULTIAPPEND+
# TODO...
#++
#
#--
# ==== RFC3516: +BINARY+
# TODO...
#++
#
# ==== RFC3691: +UNSELECT+
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051], so it is also
# listed with {Core IMAP commands}[rdoc-ref:Net::IMAP@Core+IMAP+commands].
# - #unselect: Closes the mailbox and returns to the "_authenticated_" state,
# without expunging any messages.
#
# ==== RFC4314: +ACL+
# - #getacl: lists the authenticated user's access rights to a mailbox.
# - #setacl: sets the access rights for a user on a mailbox
#--
# TODO: #deleteacl, #listrights, #myrights
#++
# - *_Note:_* +DELETEACL+, +LISTRIGHTS+, and +MYRIGHTS+ are not supported yet.
#
# ==== RFC4315: +UIDPLUS+
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051], so it is also
# listed with {Core IMAP commands}[rdoc-ref:Net::IMAP@Core+IMAP+commands].
# - #uid_expunge: Restricts #expunge to only remove the specified UIDs.
# - Updates #select, #examine with the +UIDNOTSTICKY+ ResponseCode
# - Updates #append with the +APPENDUID+ ResponseCode
# - Updates #copy, #move with the +COPYUID+ ResponseCode
#
#--
# ==== RFC4466: Collected Extensions to IMAP4 ABNF
# TODO...
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051], this RFC updates
# the protocol to enable new optional parameters to many commands: #select,
# #examine, #create, #rename, #fetch, #uid_fetch, #store, #uid_store, #search,
# #uid_search, and #append. However, specific parameters are not defined.
# Extensions to these commands use this syntax whenever possible. Net::IMAP
# may be partially compatible with extensions to these commands, even without
# any explicit support.
#++
#
#--
# ==== RFC4731 +ESEARCH+
# TODO...
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051].
# - Updates #search, #uid_search to accept result options: +MIN+, +MAX+,
# +ALL+, +COUNT+, and to return ExtendedSearchData.
#++
#
#--
# ==== RFC4959: +SASL-IR+
# TODO...
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051].
# - Updates #authenticate to reduce round-trips for supporting mechanisms.
#++
#
#--
# ==== RFC4978: COMPRESS=DEFLATE
# TODO...
#++
#
#--
# ==== RFC5182 +SEARCHRES+
# TODO...
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051].
# - Updates #search, #uid_search with the +SAVE+ result option.
# - Updates #copy, #uid_copy, #fetch, #uid_fetch, #move, #uid_move, #search,
# #uid_search, #store, #uid_store, and #uid_expunge with ability to
# reference the saved result of a previous #search or #uid_search command.
#++
#
# ==== RFC5256: +SORT+
# - #sort, #uid_sort: An alternate version of #search or #uid_search which
# sorts the results by specified keys.
# ==== RFC5256: +THREAD+
# - #thread, #uid_thread: An alternate version of #search or #uid_search,
# which arranges the results into ordered groups or threads according to a
# chosen algorithm.
#
#--
# ==== RFC5258 +LIST-EXTENDED+
# TODO...
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051], this updates the
# protocol with new optional parameters to the #list command, adding a few of
# its own. Net::IMAP may be forward-compatible with future #list extensions,
# even without any explicit support.
# - Updates #list to accept selection options: +SUBSCRIBED+, +REMOTE+, and
# +RECURSIVEMATCH+, and return options: +SUBSCRIBED+ and +CHILDREN+.
#++
#
#--
# ==== RFC5819 +LIST-STATUS+
# TODO...
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051].
# - Updates #list with +STATUS+ return option.
#++
#
# ==== +XLIST+ (non-standard, deprecated)
# - #xlist: replaced by +SPECIAL-USE+ attributes in #list responses.
#
#--
# ==== RFC6154 +SPECIAL-USE+
# TODO...
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051].
# - Updates #list with the +SPECIAL-USE+ selection and return options.
#++
#
# ==== RFC6851: +MOVE+
# Folded into IMAP4rev2[https://tools.ietf.org/html/rfc9051], so it is also
# listed with {Core IMAP commands}[rdoc-ref:Net::IMAP@Core+IMAP+commands].
# - #move, #uid_move: Moves the specified messages to the end of the
# specified destination mailbox, expunging them from the current mailbox.
#
#--
# ==== RFC6855: UTF8=ACCEPT
# TODO...
# ==== RFC6855: UTF8=ONLY
# TODO...
#++
#
#--
# ==== RFC7888: <tt>LITERAL+</tt>, +LITERAL-+
# TODO...
# ==== RFC7162: +QRESYNC+
# TODO...
# ==== RFC7162: +CONDSTORE+
# TODO...
# ==== RFC8474: +OBJECTID+
# TODO...
# ==== RFC9208: +QUOTA+
# TODO...
#++
#
# === Handling server responses
#
# - #greeting: The server's initial untagged response, which can indicate a
# pre-authenticated connection.
# - #responses: The untagged responses, as a hash. Keys are the untagged
# response type (e.g. "OK", "FETCH", "FLAGS") and response code (e.g.
# "ALERT", "UIDVALIDITY", "UIDNEXT", "TRYCREATE", etc). Values are arrays
# of UntaggedResponse or ResponseCode.
# - #add_response_handler: Add a block to be called inside the receiver thread
# with every server response.
# - #remove_response_handler: Remove a previously added response handler.
#
#
# == References
#--
# TODO: Consider moving references list to REFERENCES.md or REFERENCES.rdoc.
#++
#
# [{IMAP4rev1}[https://www.rfc-editor.org/rfc/rfc3501.html]]::
# Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - \VERSION 4rev1",
# RFC 3501, DOI 10.17487/RFC3501, March 2003,
# <https://www.rfc-editor.org/info/rfc3501>.
#
# [IMAP-ABNF-EXT[https://www.rfc-editor.org/rfc/rfc4466.html]]::
# Melnikov, A. and C. Daboo, "Collected Extensions to IMAP4 ABNF",
# RFC 4466, DOI 10.17487/RFC4466, April 2006,
# <https://www.rfc-editor.org/info/rfc4466>.
#
# <em>Note: Net::IMAP cannot parse the entire RFC4466 grammar yet.</em>
#
# [{IMAP4rev2}[https://www.rfc-editor.org/rfc/rfc9051.html]]::
# Melnikov, A., Ed., and B. Leiba, Ed., "Internet Message Access Protocol
# (\IMAP) - Version 4rev2", RFC 9051, DOI 10.17487/RFC9051, August 2021,
# <https://www.rfc-editor.org/info/rfc9051>.
#
# <em>Note: Net::IMAP is not fully compatible with IMAP4rev2 yet.</em>
#
# [IMAP-IMPLEMENTATION[https://www.rfc-editor.org/info/rfc2683]]::
# Leiba, B., "IMAP4 Implementation Recommendations",
# RFC 2683, DOI 10.17487/RFC2683, September 1999,
# <https://www.rfc-editor.org/info/rfc2683>.
#
# [IMAP-MULTIACCESS[https://www.rfc-editor.org/info/rfc2180]]::
# Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", RFC 2180, DOI
# 10.17487/RFC2180, July 1997, <https://www.rfc-editor.org/info/rfc2180>.
#
# [UTF7[https://tools.ietf.org/html/rfc2152]]::
# Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe Transformation Format of
# Unicode", RFC 2152, DOI 10.17487/RFC2152, May 1997,
# <https://www.rfc-editor.org/info/rfc2152>.
#
# === Message envelope and body structure
#
# [RFC5322[https://tools.ietf.org/html/rfc5322]]::
# Resnick, P., Ed., "Internet Message Format",
# RFC 5322, DOI 10.17487/RFC5322, October 2008,
# <https://www.rfc-editor.org/info/rfc5322>.
#
# <em>Note: obsoletes</em>
# RFC-2822[https://tools.ietf.org/html/rfc2822]<em> (April 2001) and</em>
# RFC-822[https://tools.ietf.org/html/rfc822]<em> (August 1982).</em>
#
# [CHARSET[https://tools.ietf.org/html/rfc2978]]::
# Freed, N. and J. Postel, "IANA Charset Registration Procedures", BCP 19,
# RFC 2978, DOI 10.17487/RFC2978, October 2000,
# <https://www.rfc-editor.org/info/rfc2978>.
#
# [DISPOSITION[https://tools.ietf.org/html/rfc2183]]::
# Troost, R., Dorner, S., and K. Moore, Ed., "Communicating Presentation
# Information in Internet Messages: The Content-Disposition Header
# Field", RFC 2183, DOI 10.17487/RFC2183, August 1997,
# <https://www.rfc-editor.org/info/rfc2183>.
#
# [MIME-IMB[https://tools.ietf.org/html/rfc2045]]::
# Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions
# (MIME) Part One: Format of Internet Message Bodies",
# RFC 2045, DOI 10.17487/RFC2045, November 1996,
# <https://www.rfc-editor.org/info/rfc2045>.
#
# [MIME-IMT[https://tools.ietf.org/html/rfc2046]]::
# Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions
# (MIME) Part Two: Media Types", RFC 2046, DOI 10.17487/RFC2046,
# November 1996, <https://www.rfc-editor.org/info/rfc2046>.
#
# [MIME-HDRS[https://tools.ietf.org/html/rfc2047]]::
# Moore, K., "MIME (Multipurpose Internet Mail Extensions) Part Three:
# Message Header Extensions for Non-ASCII Text",
# RFC 2047, DOI 10.17487/RFC2047, November 1996,
# <https://www.rfc-editor.org/info/rfc2047>.
#
# [RFC2231[https://tools.ietf.org/html/rfc2231]]::
# Freed, N. and K. Moore, "MIME Parameter Value and Encoded Word
# Extensions: Character Sets, Languages, and Continuations",
# RFC 2231, DOI 10.17487/RFC2231, November 1997,
# <https://www.rfc-editor.org/info/rfc2231>.
#
# [I18n-HDRS[https://tools.ietf.org/html/rfc6532]]::
# Yang, A., Steele, S., and N. Freed, "Internationalized Email Headers",
# RFC 6532, DOI 10.17487/RFC6532, February 2012,
# <https://www.rfc-editor.org/info/rfc6532>.
#
# [LANGUAGE-TAGS[https://www.rfc-editor.org/info/rfc3282]]::
# Alvestrand, H., "Content Language Headers",
# RFC 3282, DOI 10.17487/RFC3282, May 2002,
# <https://www.rfc-editor.org/info/rfc3282>.
#
# [LOCATION[https://www.rfc-editor.org/info/rfc2557]]::
# Palme, J., Hopmann, A., and N. Shelness, "MIME Encapsulation of
# Aggregate Documents, such as HTML (MHTML)",
# RFC 2557, DOI 10.17487/RFC2557, March 1999,
# <https://www.rfc-editor.org/info/rfc2557>.
#
# [MD5[https://tools.ietf.org/html/rfc1864]]::
# Myers, J. and M. Rose, "The Content-MD5 Header Field",
# RFC 1864, DOI 10.17487/RFC1864, October 1995,
# <https://www.rfc-editor.org/info/rfc1864>.
#
#--
# TODO: Document IMAP keywords.
#
# [RFC3503[https://tools.ietf.org/html/rfc3503]]
# Melnikov, A., "Message Disposition Notification (MDN)
# profile for Internet Message Access Protocol (IMAP)",
# RFC 3503, DOI 10.17487/RFC3503, March 2003,
# <https://www.rfc-editor.org/info/rfc3503>.
#++
#
# === Supported \IMAP Extensions
#
# [QUOTA[https://tools.ietf.org/html/rfc2087]]::
# Myers, J., "IMAP4 QUOTA extension", RFC 2087, DOI 10.17487/RFC2087,
# January 1997, <https://www.rfc-editor.org/info/rfc2087>.
#--
# TODO: test compatibility with updated QUOTA extension:
# [QUOTA[https://tools.ietf.org/html/rfc9208]]::
# Melnikov, A., "IMAP QUOTA Extension", RFC 9208, DOI 10.17487/RFC9208,
# March 2022, <https://www.rfc-editor.org/info/rfc9208>.
#++
# [IDLE[https://tools.ietf.org/html/rfc2177]]::
# Leiba, B., "IMAP4 IDLE command", RFC 2177, DOI 10.17487/RFC2177,
# June 1997, <https://www.rfc-editor.org/info/rfc2177>.
# [NAMESPACE[https://tools.ietf.org/html/rfc2342]]::
# Gahrns, M. and C. Newman, "IMAP4 Namespace", RFC 2342,
# DOI 10.17487/RFC2342, May 1998, <https://www.rfc-editor.org/info/rfc2342>.
# [ID[https://tools.ietf.org/html/rfc2971]]::
# Showalter, T., "IMAP4 ID extension", RFC 2971, DOI 10.17487/RFC2971,
# October 2000, <https://www.rfc-editor.org/info/rfc2971>.
# [ACL[https://tools.ietf.org/html/rfc4314]]::
# Melnikov, A., "IMAP4 Access Control List (ACL) Extension", RFC 4314,
# DOI 10.17487/RFC4314, December 2005,
# <https://www.rfc-editor.org/info/rfc4314>.
# [UIDPLUS[https://www.rfc-editor.org/rfc/rfc4315.html]]::
# Crispin, M., "Internet Message Access Protocol (\IMAP) - UIDPLUS
# extension", RFC 4315, DOI 10.17487/RFC4315, December 2005,
# <https://www.rfc-editor.org/info/rfc4315>.
# [SORT[https://tools.ietf.org/html/rfc5256]]::
# Crispin, M. and K. Murchison, "Internet Message Access Protocol - SORT and
# THREAD Extensions", RFC 5256, DOI 10.17487/RFC5256, June 2008,
# <https://www.rfc-editor.org/info/rfc5256>.
# [THREAD[https://tools.ietf.org/html/rfc5256]]::
# Crispin, M. and K. Murchison, "Internet Message Access Protocol - SORT and
# THREAD Extensions", RFC 5256, DOI 10.17487/RFC5256, June 2008,
# <https://www.rfc-editor.org/info/rfc5256>.
# [RFC5530[https://www.rfc-editor.org/rfc/rfc5530.html]]::
# Gulbrandsen, A., "IMAP Response Codes", RFC 5530, DOI 10.17487/RFC5530,
# May 2009, <https://www.rfc-editor.org/info/rfc5530>.
# [MOVE[https://tools.ietf.org/html/rfc6851]]::
# Gulbrandsen, A. and N. Freed, Ed., "Internet Message Access Protocol
# (\IMAP) - MOVE Extension", RFC 6851, DOI 10.17487/RFC6851, January 2013,
# <https://www.rfc-editor.org/info/rfc6851>.
#
# === IANA registries
#
# * {IMAP Capabilities}[http://www.iana.org/assignments/imap4-capabilities]
# * {IMAP Response Codes}[https://www.iana.org/assignments/imap-response-codes/imap-response-codes.xhtml]
# * {IMAP Mailbox Name Attributes}[https://www.iana.org/assignments/imap-mailbox-name-attributes/imap-mailbox-name-attributes.xhtml]
# * {IMAP and JMAP Keywords}[https://www.iana.org/assignments/imap-jmap-keywords/imap-jmap-keywords.xhtml]
# * {IMAP Threading Algorithms}[https://www.iana.org/assignments/imap-threading-algorithms/imap-threading-algorithms.xhtml]
#--
# * {IMAP Quota Resource Types}[http://www.iana.org/assignments/imap4-capabilities#imap-capabilities-2]
# * [{LIST-EXTENDED options and responses}[https://www.iana.org/assignments/imap-list-extended/imap-list-extended.xhtml]
# * {IMAP METADATA Server Entry and Mailbox Entry Registries}[https://www.iana.org/assignments/imap-metadata/imap-metadata.xhtml]
# * {IMAP ANNOTATE Extension Entries and Attributes}[https://www.iana.org/assignments/imap-annotate-extension/imap-annotate-extension.xhtml]
# * {IMAP URLAUTH Access Identifiers and Prefixes}[https://www.iana.org/assignments/urlauth-access-ids/urlauth-access-ids.xhtml]
# * {IMAP URLAUTH Authorization Mechanism Registry}[https://www.iana.org/assignments/urlauth-authorization-mechanism-registry/urlauth-authorization-mechanism-registry.xhtml]
#++
# * {SASL Mechanisms and SASL SCRAM Family Mechanisms}[https://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml]
# * {Service Name and Transport Protocol Port Number Registry}[https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml]:
# +imap+: tcp/143, +imaps+: tcp/993
# * {GSSAPI/Kerberos/SASL Service Names}[https://www.iana.org/assignments/gssapi-service-names/gssapi-service-names.xhtml]:
# +imap+
# * {Character sets}[https://www.iana.org/assignments/character-sets/character-sets.xhtml]
#
class IMAP < Protocol
VERSION = "0.3.4.1"
include MonitorMixin
if defined?(OpenSSL::SSL)
include OpenSSL
include SSL
end
# Returns the initial greeting the server, an UntaggedResponse.
attr_reader :greeting
# Returns recorded untagged responses.
#
# For example:
#
# imap.select("inbox")
# p imap.responses["EXISTS"][-1]
# #=> 2
# p imap.responses["UIDVALIDITY"][-1]
# #=> 968263756
attr_reader :responses
# Returns all response handlers.
attr_reader :response_handlers
# Seconds to wait until a connection is opened.
# If the IMAP object cannot open a connection within this time,
# it raises a Net::OpenTimeout exception. The default value is 30 seconds.
attr_reader :open_timeout
# Seconds to wait until an IDLE response is received.
attr_reader :idle_response_timeout
attr_accessor :client_thread # :nodoc:
# Returns the debug mode.
def self.debug
return @@debug
end
# Sets the debug mode.
def self.debug=(val)
return @@debug = val
end
# The default port for IMAP connections, port 143
def self.default_port
return PORT
end
# The default port for IMAPS connections, port 993
def self.default_tls_port
return SSL_PORT
end
class << self
alias default_imap_port default_port
alias default_imaps_port default_tls_port
alias default_ssl_port default_tls_port
end
# Disconnects from the server.
#
# Related: #logout
def disconnect
return if disconnected?
begin
begin
# try to call SSL::SSLSocket#io.
@sock.io.shutdown
rescue NoMethodError
# @sock is not an SSL::SSLSocket.
@sock.shutdown
end
rescue Errno::ENOTCONN
# ignore `Errno::ENOTCONN: Socket is not connected' on some platforms.
rescue Exception => e
@receiver_thread.raise(e)
end
@receiver_thread.join
synchronize do
@sock.close
end
raise e if e
end
# Returns true if disconnected from the server.
#
# Related: #logout, #disconnect
def disconnected?
return @sock.closed?
end
# Sends a {CAPABILITY command [IMAP4rev1 §6.1.1]}[https://www.rfc-editor.org/rfc/rfc3501#section-6.1.1]
# and returns an array of capabilities that the server supports. Each
# capability is a string.
#
# See the {IANA IMAP4 capabilities
# registry}[http://www.iana.org/assignments/imap4-capabilities] for a list
# of all standard capabilities, and their reference RFCs.
#
# >>>
# <em>*Note* that Net::IMAP does not currently modify its
# behaviour according to the capabilities of the server;
# it is up to the user of the class to ensure that
# a certain capability is supported by a server before
# using it.</em>
#
# Capability requirements—other than +IMAP4rev1+—are listed in the
# documentation for each command method.
#
# ===== Basic IMAP4rev1 capabilities
#
# All IMAP4rev1 servers must include +IMAP4rev1+ in their capabilities list.
# All IMAP4rev1 servers must _implement_ the +STARTTLS+,
# <tt>AUTH=PLAIN</tt>, and +LOGINDISABLED+ capabilities, and clients must
# respect their presence or absence. See the capabilites requirements on
# #starttls, #login, and #authenticate.
#
# ===== Using IMAP4rev1 extensions
#
# IMAP4rev1 servers must not activate incompatible behavior until an
# explicit client action invokes a capability, e.g. sending a command or
# command argument specific to that capability. Extensions with backward
# compatible behavior, such as response codes or mailbox attributes, may
# be sent at any time.
#
# Invoking capabilities which are unknown to Net::IMAP may cause unexpected
# behavior and errors, for example ResponseParseError is raised when unknown
# response syntax is received. Invoking commands or command parameters that
# are unsupported by the server may raise NoResponseError, BadResponseError,
# or cause other unexpected behavior.
#
# ===== Caching +CAPABILITY+ responses
#
# Servers may send their capability list, unsolicited, using the
# +CAPABILITY+ response code or an untagged +CAPABILITY+ response. These
# responses can be retrieved and cached using #responses or
# #add_response_handler.
#
# But cached capabilities _must_ be discarded after #starttls, #login, or
# #authenticate. The OK TaggedResponse to #login and #authenticate may
# include +CAPABILITY+ response code data, but the TaggedResponse for
# #starttls is sent clear-text and cannot be trusted.
#
def capability
synchronize do
send_command("CAPABILITY")
return @responses.delete("CAPABILITY")[-1]
end
end
# Sends an {ID command [RFC2971 §3.1]}[https://www.rfc-editor.org/rfc/rfc2971#section-3.1]
# and returns a hash of the server's response, or nil if the server does not
# identify itself.
#
# Note that the user should first check if the server supports the ID
# capability. For example:
#
# capabilities = imap.capability
# if capabilities.include?("ID")
# id = imap.id(
# name: "my IMAP client (ruby)",
# version: MyIMAP::VERSION,
# "support-url": "mailto:bugs@example.com",
# os: RbConfig::CONFIG["host_os"],
# )
# end
#
# See [ID[https://tools.ietf.org/html/rfc2971]] for field definitions.
#
# ===== Capabilities
#
# The server's capabilities must include +ID+
# [RFC2971[https://tools.ietf.org/html/rfc2971]]
def id(client_id=nil)
synchronize do
send_command("ID", ClientID.new(client_id))
@responses.delete("ID")&.last
end
end
# Sends a {NOOP command [IMAP4rev1 §6.1.2]}[https://www.rfc-editor.org/rfc/rfc3501#section-6.1.2]
# to the server.
#
# This allows the server to send unsolicited untagged EXPUNGE #responses,
# but does not execute any client request. \IMAP servers are permitted to
# send unsolicited untagged responses at any time, except for `EXPUNGE`.
#
# * +EXPUNGE+ can only be sent while a command is in progress.
# * +EXPUNGE+ must _not_ be sent during #fetch, #store, or #search.
# * +EXPUNGE+ may be sent during #uid_fetch, #uid_store, or #uid_search.
#
# Related: #idle, #check
def noop
send_command("NOOP")
end
# Sends a {LOGOUT command [IMAP4rev1 §6.1.3]}[https://www.rfc-editor.org/rfc/rfc3501#section-6.1.3]
# to inform the command to inform the server that the client is done with
# the connection.
#
# Related: #disconnect
def logout
send_command("LOGOUT")
end
# Sends a {STARTTLS command [IMAP4rev1 §6.2.1]}[https://www.rfc-editor.org/rfc/rfc3501#section-6.2.1]
# to start a TLS session.
#
# Any +options+ are forwarded to OpenSSL::SSL::SSLContext#set_params.
#
# This method returns after TLS negotiation and hostname verification are
# both successful. Any error indicates that the connection has not been
# secured.
#
# *Note:*
# >>>
# Any #response_handlers added before STARTTLS should be aware that the
# TaggedResponse to STARTTLS is sent clear-text, _before_ TLS negotiation.
# TLS negotiation starts immediately after that response.
#
# Related: Net::IMAP.new, #login, #authenticate
#
# ===== Capability
#
# The server's capabilities must include +STARTTLS+.
#
# Server capabilities may change after #starttls, #login, and #authenticate.
# Cached capabilities _must_ be invalidated after this method completes.
#
# The TaggedResponse to #starttls is sent clear-text, so the server <em>must
# *not*</em> send capabilities in the #starttls response and clients <em>must
# not</em> use them if they are sent. Servers will generally send an
# unsolicited untagged response immeditely _after_ #starttls completes.
#
def starttls(options = {}, verify = true)
send_command("STARTTLS") do |resp|
if resp.kind_of?(TaggedResponse) && resp.name == "OK"
begin
# for backward compatibility
certs = options.to_str
options = create_ssl_params(certs, verify)
rescue NoMethodError
end
start_tls_session(options)
end
end
end
# :call-seq:
# authenticate(mechanism, ...) -> ok_resp
# authenticate(mech, *creds, **props) {|prop, auth| val } -> ok_resp
# authenticate(mechanism, authnid, credentials, authzid=nil) -> ok_resp
# authenticate(mechanism, **properties) -> ok_resp
# authenticate(mechanism) {|propname, authctx| prop_value } -> ok_resp
#
# Sends an {AUTHENTICATE command [IMAP4rev1 §6.2.2]}[https://www.rfc-editor.org/rfc/rfc3501#section-6.2.2]
# to authenticate the client. If successful, the connection enters the
# "_authenticated_" state.
#
# +mechanism+ is the name of the \SASL authentication mechanism to be used.
# All other arguments are forwarded to the authenticator for the requested
# mechanism. The listed call signatures are suggestions. <em>The
# documentation for each individual mechanism must be consulted for its
# specific parameters.</em>
#
# An exception Net::IMAP::NoResponseError is raised if authentication fails.
#
# Related: #login, #starttls
#
# ==== Supported SASL Mechanisms
#
# +PLAIN+:: See PlainAuthenticator.
# Login using clear-text username and password.
#
# +XOAUTH2+:: See XOauth2Authenticator.
# Login using a username and OAuth2 access token.
# Non-standard and obsoleted by +OAUTHBEARER+, but widely
# supported.
#
# >>>
# *Deprecated:* <em>Obsolete mechanisms are available for backwards
# compatibility.</em>
#
# For +DIGEST-MD5+ see DigestMD5Authenticator.
#
# For +LOGIN+, see LoginAuthenticator.
#
# For +CRAM-MD5+, see CramMD5Authenticator.
#
# <em>Using a deprecated mechanism will print a warning.</em>
#
# See Net::IMAP::Authenticators for information on plugging in
# authenticators for other mechanisms. See the {SASL mechanism
# registry}[https://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml]
# for information on these and other SASL mechanisms.