requests 2.32.3 with IPv6 link local address fails with error: [Errno -2] Name or service not known

[pytech66]

When using an IPv6 link local address with requests > v2.31.0, seeing an error [Errno -2] Name or service not known. The same works with requests 2.31.0.
urllib3 2.2.1 also works successfully with IPv6 link local address .

urllib3 2.2.1 with IPv6 link local address

>>> import urllib3
>>> http = urllib3.PoolManager(cert_reqs='CERT_NONE')
>>> res = http.request("GET", "https://[fe80::5eed:8cff:fe00:0da4%ens192]/redfish/v1")
/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connectionpool.py:1103: InsecureRequestWarning: Unverified HTTPS request is being made to host 'fe80::5eed:8cff:fe00:0da4%ens192'. Adding certificate verification is strongly advised. See: https://urllib3.readthedocs.io/en/latest/advanced-usage.html#tls-warnings
  warnings.warn(
>>> res.status
200

requests 2.31.0 with IPv6 link local address

>>> import requests
>>> res = requests.get("https://[fe80::5eed:8cff:fe00:0da4%ens192]/redfish/v1", verify=False)
>>> res.status_code
200

Expected Result

Successful connection with versions 2.32.x

Actual Result

>>> import requests
>>> res = requests.get("https://[fe80::5eed:8cff:fe00:0da4%ens192]/redfish/v1", verify=False)
Traceback (most recent call last):
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connection.py", line 198, in _new_conn
    sock = connection.create_connection(
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/util/connection.py", line 60, in create_connection
    for res in socket.getaddrinfo(host, port, family, socket.SOCK_STREAM):
  File "/usr/lib/python3.10/socket.py", line 955, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -2] Name or service not known

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 793, in urlopen
    response = self._make_request(
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 491, in _make_request
    raise new_e
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 467, in _make_request
    self._validate_conn(conn)
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 1099, in _validate_conn
    conn.connect()
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connection.py", line 616, in connect
    self.sock = sock = self._new_conn()
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connection.py", line 205, in _new_conn
    raise NameResolutionError(self.host, self, e) from e
urllib3.exceptions.NameResolutionError: <urllib3.connection.HTTPSConnection object at 0x716b63d403d0>: Failed to resolve 'fe80::5eed:8cf00:0da4%25ens192' ([Errno -2] Name or service not known)

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/root/new-requests/venv/lib/python3.10/site-packages/requests/adapters.py", line 667, in send
    resp = conn.urlopen(
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 847, in urlopen
    retries = retries.increment(
  File "/root/new-requests/venv/lib/python3.10/site-packages/urllib3/util/retry.py", line 515, in increment
    raise MaxRetryError(_pool, url, reason) from reason  # type: ignore[arg-type]
urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host='fe80::5eed:8cff:fe00:0da4%25ens192', port=443): Max retries exceeded with urredfish/v1 (Caused by NameResolutionError("<urllib3.connection.HTTPSConnection object at 0x716b63d403d0>: Failed to resolve 'fe80::5eed::fe00:0da4%25ens192' ([Errno -2] Name or service not known)"))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/root/new-requests/venv/lib/python3.10/site-packages/requests/api.py", line 73, in get
    return request("get", url, params=params, **kwargs)
  File "/root/new-requests/venv/lib/python3.10/site-packages/requests/api.py", line 59, in request
    return session.request(method=method, url=url, **kwargs)
  File "/root/new-requests/venv/lib/python3.10/site-packages/requests/sessions.py", line 589, in request
    resp = self.send(prep, **send_kwargs)
  File "/root/new-requests/venv/lib/python3.10/site-packages/requests/sessions.py", line 703, in send
    r = adapter.send(request, **kwargs)
  File "/root/new-requests/venv/lib/python3.10/site-packages/requests/adapters.py", line 700, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='fe80::5eed:8cff:fe00:0da4%25ens192', port=443): Max retries exceeded with: /redfish/v1 (Caused by NameResolutionError("<urllib3.connection.HTTPSConnection object at 0x716b63d403d0>: Failed to resolve 'fe80::5ecff:fe00:0da4%25ens192' ([Errno -2] Name or service not known)"))

Reproduction Steps

import requests
res = requests.get("https://[fe80::5eed:8cff:fe00:0da4%ens192]/redfish/v1", verify=False)

System Information

$ python -m requests.help

{
  "chardet": {
    "version": null
  },
  "charset_normalizer": {
    "version": "3.3.2"
  },
  "cryptography": {
    "version": ""
  },
  "idna": {
    "version": "3.7"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.10.12"
  },
  "platform": {
    "release": "6.5.0-27-generic",
    "system": "Linux"
  },
  "pyOpenSSL": {
    "openssl_version": "",
    "version": null
  },
  "requests": {
    "version": "2.32.3"
  },
  "system_ssl": {
    "version": "30000020"
  },
  "urllib3": {
    "version": "2.2.1"
  },
  "using_charset_normalizer": true,
  "using_pyopenssl": false
}

[mattiaswal]

I worked around the bug with:

# Workaround for bug in requests 2.32.x: https://github.com/psf/requests/issues/6735
def requests_workaround(method, url, json, headers, auth, verify=False):
    # Create a session
        session=requests.Session()

        # Prepare the request
        request=requests.Request(method, url, json=json, headers=headers, auth=auth)
        prepared_request=session.prepare_request(request)
        prepared_request.url=prepared_request.url.replace('%25', '%')
        return session.send(prepared_request, verify=verify)

def requests_workaround_put(url, json, headers, auth, verify=False):
    return requests_workaround('PUT', url, json, headers, auth, verify=False)

def requests_workaround_delete(url, headers, auth, verify=False):
    return requests_workaround('DELETE', url, None, headers, auth, verify=False)

def requests_workaround_post(url, json, headers, auth, verify=False):
    return requests_workaround('POST', url, json, headers, auth, verify=False)

def requests_workaround_get(url, headers, auth, verify=False):
    return requests_workaround('GET', url, None, headers, auth, verify=False)