Mitmproxy as a windows service fails to SSL

Problem Description

Mitmproxy works fine if run directly but fails to intercept SSL requests when run as a windows service. I run the code as Administrator.

Steps to reproduce the behavior:

This code works fine:

class AddHeader:
    def __init__(self):
        self.num = 0

    def response(self, flow):
        self.num = self.num + 1
        flow.response.headers["count"] = str(self.num)

if __name__ == '__main__':
    options = Options(listen_host='127.0.0.1', listen_port=8081)
    config = ProxyConfig(options)
    master = ProxyMaster(options, with_termlog=DEBUG, with_dumper=DEBUG)
    master.server = ProxyServer(config)
    master.addons.add(AddHeader())
    master.run()

But this code that uses mitmproxy within a service does not work and produces an error:

import socket

import win32serviceutil

import servicemanager
import win32event
import win32service

from mitmproxy.options import Options
from mitmproxy.proxy.config import ProxyConfig
from mitmproxy.proxy.server import ProxyServer
from mitmproxy.tools.dump import DumpMaster

class SMWinservice(win32serviceutil.ServiceFramework):
    '''Base class to create winservice in Python'''

    _svc_name_ = 'pythonService'
    _svc_display_name_ = 'Python Service'
    _svc_description_ = 'Python Service Description'

    @classmethod
    def parse_command_line(cls):
        '''
        ClassMethod to parse the command line
        '''
        win32serviceutil.HandleCommandLine(cls)

    def __init__(self, args):
        '''
        Constructor of the winservice
        '''
        win32serviceutil.ServiceFramework.__init__(self, args)
        self.hWaitStop = win32event.CreateEvent(None, 0, 0, None)
        socket.setdefaulttimeout(60)

    def SvcStop(self):
        '''
        Called when the service is asked to stop
        '''
        self.stop()
        self.ReportServiceStatus(win32service.SERVICE_STOP_PENDING)
        win32event.SetEvent(self.hWaitStop)

    def SvcDoRun(self):
        '''
        Called when the service is asked to start
        '''
        #self.ReportServiceStatus(win32service.SERVICE_RUNNING)
        self.start()
        servicemanager.LogMsg(servicemanager.EVENTLOG_INFORMATION_TYPE,
                              servicemanager.PYS_SERVICE_STARTED,
                              (self._svc_name_, ''))
        self.main()

    def start(self):
        '''
        Override to add logic before the start
        eg. running condition
        '''
        pass

    def stop(self):
        '''
        Override to add logic before the stop
        eg. invalidating running condition
        '''
        pass

    def main(self):
        '''
        Main class to be overridden to add logic
        '''
        pass

class AddHeader:
    def __init__(self):
        self.num = 0

    def response(self, flow):
        self.num = self.num + 1
        flow.response.headers["count"] = str(self.num)

class PythonCornerExample(SMWinservice):
    _svc_name_ = "service"
    _svc_display_name_ = "just a service"
    _svc_description_ = "doesn't do much"

    def start(self):
        self._install()
        self.isrunning = True

    def stop(self):
        self.isrunning = False
        self.master.shutdown()

    def main(self):
        options = Options(listen_host='127.0.0.1', listen_port=8081, confdir=r"C:\Users\username\.mitmproxy")
        config = ProxyConfig(options)
        self.master = ProxyMaster(options, with_termlog=True, with_dumper=True)
        self.master.server = ProxyServer(config)
        self.master.addons.add(AddHeader())

        try:
            self.master.run()
        except Exception as e:
            servicemanager.LogErrorMsg("Some error happened running MitmProxy. Is port 8080 free?\n{}".format(e))

if __name__ == '__main__':
    PythonCornerExample.parse_command_line()

The error happens when an SSL packet gets to mitmproxy: << Cannot establish TLS with example.com:443 (sni: example.com): TlsException('SSL handshake error: WantReadError()')

And can be run with:

python script.py debug

I set confdir=r"C:\Users\username\.mitmproxy" just in case since it runs as Administrator it is not looking for the certs in the folder where I have them but still fails. What am I missing? Thank you in advance

System Information

Mitmproxy: 5.3.0
Python:    3.7.1
OpenSSL:   OpenSSL 1.1.1h  22 Sep 2020
Platform:  Windows-10-10.0.20241-SP0

[illera88]

It’s fixed in 7.0

[mhils]

FYI, everything in mitmproxy.proxy is about to be swapped out with a new sans-io implementation in a few days/weeks. You may want to take a look at the sans-io branch, which could also give you a better error message here. See #1775 and https://github.com/mitmproxy/mitmproxy/projects/4. I think we’re unlikely to merge nontrivial changes to mitmproxy.proxy until then.