mailu/optional/fetchmail/fetchmail.py

#!/usr/bin/python3

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


FETCHMAIL = """
fetchmail -N \
    --idfile /data/fetchids --uidl \
    --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 "".join("\\x%2x" % ord(char) for char in arg)


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):
    try:
        fetches = requests.get("http://" + os.environ.get("HOST_ADMIN", "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 += " ssl" 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://" + os.environ.get("HOST_ADMIN", "admin") + "/internal/fetch/{}".format(fetch["id"]),
                    json=error_message.split("\n")[0]
                )
    except Exception:
        traceback.print_exc()


if __name__ == "__main__":
    while True:
        time.sleep(int(os.environ.get("FETCHMAIL_DELAY", 60)))

        if not os.environ.get("FETCHMAIL_ENABLED", 'True') in ('True', 'true'):
            continue

        run(os.environ.get("DEBUG", None) == "True")
        sys.stdout.flush()