Bug #13926
Updated by petehamilton (Pete Hamilton) over 6 years ago
When setting headers using `Net::HTTPHeader#add_field` `Net::HTTPHeader#add_header` or `Net::HTTPHeader#[]=` in v2.4.2, an `ArgumentError (invalid byte sequence in UTF-8)` is raised. In 2.4.1, this behaviour didn't exist and it looks like it was introduced in one of the revisions associated with https://bugs.ruby-lang.org/issues/13852, where the header value is matched against a regular expression to prevent newlines. Previously, `Net::HTTP` would accept non-UTF8 header values and just return them as invalid UTF8 strings. It was then on the user of `Net::HTTP` to handle this. With this change, there's now no way for the user to handle the case where they receive non-UTF8 header values as `Net::HTTP` raises an error. [RFC2616](https://tools.ietf.org/html/rfc2616#section-4.2) allowed an HTTP header field content to be made up of any non-whitespace octets. Because of this [RFC7230](https://tools.ietf.org/html/rfc7230#section-3.2.4) makes an allowance for all characters in the ISO-8859-1 charset (both lower and extended ASCII characters). Specifically, this section of RFC7230 suggests that although ideally response header values would be compatible with UTF-8, we can't assume this to be the case. > Historically, HTTP has allowed field content with text in the > ISO-8859-1 charset [ISO-8859-1], supporting other charsets only > through use of [RFC2047] encoding. In practice, most HTTP header > field values use only a subset of the US-ASCII charset [USASCII]. > Newly defined header fields SHOULD limit their field values to > US-ASCII octets. A recipient SHOULD treat other octets in field > content (obs-text) as opaque data. Not entirely sure where to go from here or what the fix is but given this is a behaviour change, it'd be great to hear your thoughts.