email_attachment_parser.py

import re
import logging
from logging import handlers as logging_handlers
import email
from email.parser import Parser
from email.header import decode_header
from email.utils import parseaddr
from StringIO import StringIO

logger = logging.getLogger(__name__)
handler = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s - %(levelname)s: %(message)s')
handler.setFormatter(formatter)
logger.addHandler(handler)
logger.setLevel(logging.INFO)


def decode_str(s):
    if not s:
        return s
    value, charset = decode_header(s)[0]
    if charset:
        value = value.decode(charset)
    return value

def decode_addr(s):
    if not s:
        return s
    header, addr = parseaddr(s)
    name = decode_str(header)
    value = '%s <%s>' % (name, addr)
    return value

def parse_payload(message):
    from_ = decode_addr(message.get('From'))
    to_ = decode_addr(message.get('To'))
    subject = decode_str(message.get('Subject'))
    if message.is_multipart():
        content = None
        attachment = None
        content_type = message.get_content_type()
        payloads = message.get_payload()
        payloads = [parse_payload(payload) for payload in payloads]
    else:
        payloads = []
        content_type = message.get_content_type()
        if content_type in ['text/plain', 'text/html']:
            content = message.get_payload(decode=True)
            attachment = None
        else:
            content = None
            file_data = message.get_payload(decode=True)
            attachment = StringIO(file_data)
            attachment.content_type = content_type
            attachment.size = len(file_data)
            attachment.name = None
            attachment.create_date = None
            attachment.modify_date = None
            attachment.read_date = None
            disp = message.get('Content-Disposition', '')
            disps = disp.strip().split(';')
            if disps[0].lower() == 'attachment':
                for param in disps[1:]:
                    param = param.strip()
                    name = param.split('=')[0]
                    rex = re.compile('"(.*)"')
                    if rex.search(param):
                        value = rex.search(param).groups()[0]
                        value = decode_str(value)
                    else:
                        logger.error('parse disposition value error')
                        value = None
                    if name == 'filename':
                        attachment.name = value
                    elif name == 'create-date':
                        attachment.create_date = value
                    elif name == 'modification-date':
                        attachment.modify_date = value
                    elif name == 'read-date':
                        attachment.read_date = value
    payload = {
            'from': from_,
            'to': to_,
            'subject': subject,
            'content_type': content_type,
            'content': content,
            'payloads': payloads,
            'attachment': attachment if attachment and attachment.name else None,
            }
    return payload

def parse_message_str(content):
    message = Parser().parsestr(content)
    payload = parse_payload(message)
    return payload


def filter_attachment(payload):
    attachments = []
    def _parse_attachment_from_payload(_payload):
        if _payload['attachment']:
            attachment = _payload['attachment']
            attachments.append(attachment)
        for __payload in _payload['payloads']:
            _parse_attachment_from_payload(__payload)
    _parse_attachment_from_payload(payload)
    return attachments


def save_attachment(attachment, name):
    with file(name, 'w') as f:
        f.write(attachment.read())
    return name

if __name__ == '__main__':
    content = file('email_content').read()
    payload = parse_message_str(content)
    attachments = filter_attachment(payload)
    for atta in attachments:
        save_attachment(atta)