Are the HTTP Connection header values case sensitive?

http, http-headers

Solution

I can’t find any explicit specification of the case-sensitivity of the Connection’s field values. But as Connection may contain the name of header fields:

[…] for each connection-token in this field, remove any header field(s) from the message with the same name as the connection-token.

and as those header field names are case-insensitive, I conclude that the Connection’s field value is also considered case-insensitive.

Problem

Are values such as `keep-alive`, `Close`, and `Upgrade` of the `Connection:` header case sensitive? I'm writing a simple web server and wondering whether I should be transforming the values to lower case before checking them.

Original source