Certain domains cannot be scanned

Hi

During my test, I receive the following error Message:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 704, in urlopen
httplib_response = self._make_request(
File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 450, in _make_request
six.raise_from(e, None)
File "", line 3, in raise_from
File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 445, in _make_request
httplib_response = conn.getresponse()
File "/usr/lib/python3.10/http/client.py", line 1374, in getresponse
response.begin()
File "/usr/lib/python3.10/http/client.py", line 318, in begin
version, status, reason = self._read_status()
File "/usr/lib/python3.10/http/client.py", line 287, in _read_status
raise RemoteDisconnected("Remote end closed connection without"
http.client.RemoteDisconnected: Remote end closed connection without response

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/requests/adapters.py", line 440, in send
resp = conn.urlopen(
File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 786, in urlopen
retries = retries.increment(
File "/usr/lib/python3/dist-packages/urllib3/util/retry.py", line 550, in increment
raise six.reraise(type(error), error, _stacktrace)
File "/usr/lib/python3/dist-packages/six.py", line 718, in reraise
raise value.with_traceback(tb)
File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 704, in urlopen
httplib_response = self._make_request(
File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 450, in _make_request
six.raise_from(e, None)
File "", line 3, in raise_from
File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 445, in _make_request
httplib_response = conn.getresponse()
File "/usr/lib/python3.10/http/client.py", line 1374, in getresponse
response.begin()
File "/usr/lib/python3.10/http/client.py", line 318, in begin
version, status, reason = self._read_status()
File "/usr/lib/python3.10/http/client.py", line 287, in _read_status
raise RemoteDisconnected("Remote end closed connection without"
urllib3.exceptions.ProtocolError: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/home/parallels/ExchangeFinder/exchangefinder.py", line 100, in
exchange_finder_domain(domains)
File "/home/parallels/ExchangeFinder/exchangefinder.py", line 70, in exchange_finder_domain
check_exchange_header(domain_to_check, useragent, output_file)
File "/home/parallels/ExchangeFinder/core/functions.py", line 70, in check_exchange_header
req = requests.get(domain, verify=False, headers=request_headers)
File "/usr/lib/python3/dist-packages/requests/api.py", line 75, in get
return request('get', url, params=params, **kwargs)
File "/usr/lib/python3/dist-packages/requests/api.py", line 61, in request
return session.request(method=method, url=url, **kwargs)
File "/usr/lib/python3/dist-packages/requests/sessions.py", line 529, in request
resp = self.send(prep, **send_kwargs)
File "/usr/lib/python3/dist-packages/requests/sessions.py", line 645, in send
r = adapter.send(request, **kwargs)
File "/usr/lib/python3/dist-packages/requests/adapters.py", line 501, in send
raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: ('Connection aborted.', RemoteDisconnected('Remote end closed connection without response'))

for my test I use to run it on the Domain microsoft.com. Domains like google.com works fine.
Do you have a hint for me what the problem could be?

Thanks

Start with exchangefinder.py at exchange_finder_domain and core/functions.py at check_exchange_header, using the traceback locations as entry points. Reproduce the scan against microsoft.com and compare it with google.com, then inspect how the connection error is handled. Done means the behavior for domains that close the connection is defined and covered by an appropriate test.

Written by the indexing model from the issue text.