fix(fetch): Correctly decode multipart/form-data names and filenames
#19145
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Currently the `multipart/form-data` parser in `Request.prototype.formData` and `Response.prototype.formData` decodes non-ASCII filenames incorrectly, instead decoding them as if they were Latin-1. This happens because the header section of each `multipart/form-data` entry is decoded as Latin-1 in order to be parsed with `Headers`, which only allows `ByteString`s, but the names and filenames are never decoded correctly. This PR fixes this as a post-processing step. Note that the `multipart/form-data` parsing for this APIs is very much underspecified, and it does not specify that names and filenames must be decoded as UTF-8. However, it does require that the bodies of non-`File` entries are decoded as UTF-8, and in browsers, names and filenames will be encoded with the same encoding as the body. Closes denoland#19142.
levex
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May 18, 2023
#19145) Currently the `multipart/form-data` parser in `Request.prototype.formData` and `Response.prototype.formData` decodes non-ASCII filenames incorrectly, as if they were encoded in Latin-1 rather than UTF-8. This happens because the header section of each `multipart/form-data` entry is decoded as Latin-1 in order to be parsed with `Headers`, which only allows `ByteString`s, but the names and filenames are never decoded correctly. This PR fixes this as a post-processing step. Note that the `multipart/form-data` parsing for this APIs in the Fetch spec is very much underspecified, and it does not specify that names and filenames must be decoded as UTF-8. However, it does require that the bodies of non-`File` entries are decoded as UTF-8, and in browsers, names and filenames always use the same encoding as the body. Closes #19142.
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Currently the
multipart/form-dataparser inRequest.prototype.formDataandResponse.prototype.formDatadecodes non-ASCII filenames incorrectly, as if they were encoded in Latin-1 rather than UTF-8. This happens because the header section of eachmultipart/form-dataentry is decoded as Latin-1 in order to be parsed withHeaders, which only allowsByteStrings, but the names and filenames are never decoded correctly. This PR fixes this as a post-processing step.Note that the
multipart/form-dataparsing for this APIs in the Fetch spec is very much underspecified, and it does not specify that names and filenames must be decoded as UTF-8. However, it does require that the bodies of non-Fileentries are decoded as UTF-8, and in browsers, names and filenames always use the same encoding as the body.Closes #19142.