mailu/optional/fetchmail/fetchmail.py

#!/usr/bin/python3

import time
import os
import tempfile
import shlex
import subprocess
import re
import requests


FETCHMAIL = """
fetchmail -N \
    --sslcertck --sslcertpath /etc/ssl/certs \
    -f {}
"""


RC_LINE = """
poll "{host}" proto {protocol}  port {port}
    user "{username}" password "{password}"
    is "{user_email}"
    smtphost "{smtphost}"
    {options}
"""


def extract_host_port(host_and_port, default_port):
    host, _, port = re.match('^(.*)(:([0-9]*))?$', host_and_port).groups()
    return host, int(port) if port else default_port


def escape_rc_string(arg):
    return arg.replace("\\", "\\\\").replace('"', '\\"')


def fetchmail(fetchmailrc):
    with tempfile.NamedTemporaryFile() as handler:
        handler.write(fetchmailrc.encode("utf8"))
        handler.flush()
        command = FETCHMAIL.format(shlex.quote(handler.name))
        output = subprocess.check_output(command, shell=True)
        return output


def run(debug):
    fetches = requests.get("http://admin/internal/fetch").json()
    smtphost, smtpport = extract_host_port(os.environ.get("HOST_SMTP", "smtp"), None)
    if smtpport is None:
        smtphostport = smtphost
    else:
        smtphostport = "%s/%d" % (smtphost, smtpport)
    for fetch in fetches:
        fetchmailrc = ""
        options = "options antispam 501, 504, 550, 553, 554"
        options += " sslmode wrapped" if fetch["tls"] else ""
        options += " keep" if fetch["keep"] else " fetchall"
        fetchmailrc += RC_LINE.format(
            user_email=escape_rc_string(fetch["user_email"]),
            protocol=fetch["protocol"],
            host=escape_rc_string(fetch["host"]),
            port=fetch["port"],
            smtphost=smtphostport,
            username=escape_rc_string(fetch["username"]),
            password=escape_rc_string(fetch["password"]),
            options=options
        )
        if debug:
            print(fetchmailrc)
        try:
            print(fetchmail(fetchmailrc))
            error_message = ""
        except subprocess.CalledProcessError as error:
            error_message = error.output.decode("utf8")
            # No mail is not an error
            if not error_message.startswith("fetchmail: No mail"):
                print(error_message)
            user_info = "for %s at %s" % (fetch["user_email"], fetch["host"])
            # Number of messages seen is not a error as well
            if ("messages" in error_message and
                    "(seen " in error_message and
                    user_info in error_message):
                print(error_message)
        finally:
            requests.post("http://admin/internal/fetch/{}".format(fetch["id"]),
                json=error_message.split("\n")[0]
            )


if __name__ == "__main__":
    while True:
        time.sleep(int(os.environ.get("FETCHMAIL_DELAY", 60)))
        run(os.environ.get("DEBUG", None) == "True")