Bad filename when having non ASCII characters

[jackdeguest]

Checklist

• I've searched for similar issues.
• I'm using the latest version of HTTPie.

---

Minimal reproduction code and steps

1. save a dummy image as 天狗.png
2. issue a multipart/form-data, such as: https --offline --multipart https://example.org name='John Doe' file_field@/home/john/天狗.png > /tmp/httpie_result.txt

Current result

The Content-Disposition header generated will be something like: Content-Disposition: form-data; name="file_field"; filename="天狗.png"
…

Expected result

The Content-Disposition header should conform to rfc2231. So this should rather be: Content-Disposition: form-data; name="file_field"; filename*=UTF-8''%E5%A4%A9%E7%8B%97.png

You can generate the proper encoded filename in accordance with rfc2231 using the perl command line perl -MEncode -MURI::Escape::XS -lE 'say URI::Escape::XS::uri_escape( Encode::decode_utf8("天狗.png") )'
…

---

Debug output

Please re-run the command with --debug, then copy the entire command & output and paste both below:

$ http --debug <COMPLETE ARGUMENT LIST THAT TRIGGERS THE ERROR>
<COMPLETE OUTPUT>

Additional information, screenshots, or code examples

…

[isidentical]

Thanks @jackdeguest, we will be looking for this one!

[arabcoders]

This is problem for downloaded content as well

[vermaxik]

@isidentical any progress here? 🙏