httplib: could not skip "ACCEPT-ENCODING" header

[song1st]

BPO	29479
Nosy	@vadmium, @iritkatriel

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-06-20.17:14:48.846>
created_at = <Date 2017-02-08.10:18:59.969>
labels = ['invalid', 'type-bug', 'library']
title = 'httplib: could not skip "ACCEPT-ENCODING" header'
updated_at = <Date 2021-06-20.17:14:48.845>
user = 'https://bugs.python.org/song1st'

bugs.python.org fields:

activity = <Date 2021-06-20.17:14:48.845>
actor = 'iritkatriel'
assignee = 'none'
closed = True
closed_date = <Date 2021-06-20.17:14:48.846>
closer = 'iritkatriel'
components = ['Library (Lib)']
creation = <Date 2017-02-08.10:18:59.969>
creator = 'song1st'
dependencies = []
files = []
hgrepos = []
issue_num = 29479
keywords = []
message_count = 4.0
messages = ['287295', '287296', '287298', '396181']
nosy_count = 3.0
nosy_names = ['martin.panter', 'song1st', 'iritkatriel']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29479'
versions = ['Python 2.7']

[song1st]

When I tried to skip "ACCEPT-ENCODING" of header, I found the behavior was not right.
I think the issue is the following two "if" in _send_request of httplib.

    def _send_request(self, method, url, body, headers):
        # Honor explicitly requested Host: and Accept-Encoding: headers.
        header_names = dict.fromkeys([k.lower() for k in headers])
        skips = {}
        if 'host' in header_names:
            skips['skip_host'] = 1
        if 'accept-encoding' in header_names:
            skips['skip_accept_encoding'] = 1

[vadmium]

Please explain what the wrong behaviour that you see is, and what you expect the right behaviour should be.

That code is intended to either keep any user-supplied Accept-Encoding header field, or send “Accept-Encoding: identity” if the field is not supplied.

If you are looking for a way to avoid adding this field entirely, see the lower level putrequest() and related methods. This is documented behaviour: <https://docs.python.org/2.7/library/httplib.html#httplib.HTTPConnection.putrequest\>.

[song1st]

Sorry, I thought I misunderstood the meaning.

I want no "ACCEPT-ENCODING" even "ACCEPT-ENCODING: identity".
I tried to modify the code from
if 'accept-encoding' in header_names:
to
if not 'accept-encoding' in header_names:

The http request will be no "ACCEPT-ENCODING".
This is what I want.

[iritkatriel]

As Martin has stated, this can be achieved with putrequest as explained in the doc:

https://docs.python.org/3.10/library/http.client.html#http.client.HTTPConnection.putrequest