Fix badly encoded charset crashing instead of falling back to detector

[PLPeeters]

What do these changes do?

They fix a crash that occurs when processing a Content-Type header that is itself badly encoded.

Example I saw in the wild was:

HTTP/1.1 200 OK
Date: Tue, 17 Sep 2024 08:02:39 GMT
Server: Apache
Vary: Accept-Encoding
Connection: close
Content-Type: text/html; charset=�gUTF-8��

where I got:

  File "/usr/local/lib/python3.12/site-packages/aiohttp/client_reqrep.py", line 1179, in text
    encoding = self.get_encoding()
               ^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/aiohttp/client_reqrep.py", line 1157, in get_encoding
    return codecs.lookup(encoding).name
           ^^^^^^^^^^^^^^^^^^^^^^^
UnicodeEncodeError: 'utf-8' codec can't encode character '\udc81' in position 0: surrogates not allowed

Yet to me, this falls under the "not understood by Python" case of the documentation:

Retrieve content encoding using charset info in Content-Type HTTP header.
If no charset is present or the charset is not understood by Python, the
fallback_charset_resolver function associated with the ClientSession is called.

Are there changes in behavior for the user?

Such websites no longer cause a UnicodeEncodeError that crashes ClientResponse.get_encoding() (and ultimately ClientResponse.text()) and will instead fallback as if it was a LookupError on the encoding. This is the behaviour I expected to see, hence the PR.

Is it a substantial burden for the maintainers to support this?

I don't think so, it might even lead to issues not being raised when they would have.

Related issue number

Sort of related to #207 and #3279.

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
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    Fixed issue with non-ascii contents in doctest text files
    -- by :user:`contributor-gh-handle`.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.31%. Comparing base (fa98921) to head (38e20f8).
Report is 1052 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #9160   +/-   ##
=======================================
  Coverage   98.31%   98.31%           
=======================================
  Files         107      107           
  Lines       34461    34475   +14     
  Branches     4089     4090    +1     
=======================================
+ Hits        33879    33893   +14     
  Misses        411      411           
  Partials      171      171           

Flag	Coverage Δ
CI-GHA	98.20% <100.00%> (+<0.01%)	⬆️
OS-Linux	97.87% <100.00%> (+<0.01%)	⬆️
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Py-3.9.20	?
Py-pypy7.3.16	97.08% <100.00%> (-0.01%)	⬇️
VM-macos	97.55% <100.00%> (+<0.01%)	⬆️
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[Dreamsorcerer]

Weird that the documentation doesn't mention these exceptions, but I think the change is correct.

[patchback]

Backport to 3.10: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 8ad118b on top of patchback/backports/3.10/8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae/pr-9160

Backporting merged PR #9160 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.10/8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae/pr-9160 upstream/3.10

4. Now, cherry-pick PR Fix badly encoded charset crashing instead of falling back to detector #9160 contents into that branch:

   $ git cherry-pick -x 8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae

   If it'll yell at you with something like fatal: Commit 8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Fix badly encoded charset crashing instead of falling back to detector #9160 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.10/8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae/pr-9160

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.11: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 8ad118b on top of patchback/backports/3.11/8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae/pr-9160

Backporting merged PR #9160 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.11/8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae/pr-9160 upstream/3.11

4. Now, cherry-pick PR Fix badly encoded charset crashing instead of falling back to detector #9160 contents into that branch:

   $ git cherry-pick -x 8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae

   If it'll yell at you with something like fatal: Commit 8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Fix badly encoded charset crashing instead of falling back to detector #9160 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.11/8ad118b1d8b83ce0c0b61ae0cf8019c9a2fcd5ae/pr-9160

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[Dreamsorcerer]

Could you follow the above instructions for backports please?