# Copyright (C) 2018 by the Free Software Foundation, Inc.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
# USA.

"""This is a custom handler that will examine the size of a message and take
action based on various mm_cfg.py settings.  The settings are as follows

GLOBAL_MAX_MESSAGE_SIZE
    if set to a number > 0, that is the maximum number of KB for a message
    to be accepted
GLOBAL_MAX_MESSAGE_ACTION
    if GLOBAL_MAX_MESSAGE_SIZE > 0 and a message is larger than that size
    take action as follows:
    = 0, hold the message
    = 1, reject the message
    = any value other than 0 or 1, discard the message
    
This handler should be installed as Mailman/Handlers/GlobalTooBig.py and
added to the pipeline between Moderate and Hold by putting something like

GLOBAL_PIPELINE.insert(GLOBAL_PIPELINE.index('Hold'), 'GlobalTooBig')

in mm_cfg.py. You also must define GLOBAL_MAX_MESSAGE_SIZE in mm_cfg.py and if
it is > 0 you also must define GLOBAL_MAX_MESSAGE_ACTION.
"""

import email
from Mailman import mm_cfg
from Mailman import Errors
from Mailman.Handlers import Hold, Moderate


def process(mlist, msg, msgdata):
    # Are we doing anything?
    if mm_cfg.GLOBAL_MAX_MESSAGE_SIZE <= 0:
        return
    # Get the message size.
    bodylen = 0
    for line in email.Iterators.body_line_iterator(msg):
        bodylen += len(line)
    for part in msg.walk():
        if part.preamble:
            bodylen += len(part.preamble)
        if part.epilogue:
            bodylen += len(part.epilogue)
    if bodylen/1024.0 <= mm_cfg.GLOBAL_MAX_MESSAGE_SIZE:
        return
    if mm_cfg.GLOBAL_MAX_MESSAGE_ACTION == 0:
        # Hold the message
        Hold.hold_for_approval(mlist, msg, msgdata,
            Hold.MessageTooBig(bodylen, mm_cfg.GLOBAL_MAX_MESSAGE_SIZE))
        # No return
    elif mm_cfg.GLOBAL_MAX_MESSAGE_ACTION == 1:
        raise Errors.RejectMessage, Hold.MessageTooBig(bodylen,
            mm_cfg.GLOBAL_MAX_MESSAGE_SIZE).rejection_notice(mlist)
    else:
        # This will honor the list's forward_auto_discards setting.
        Moderate.do_discard(mlist, msg)
        # Doesn't return.