Motivation:
Commit 0d8ce23c83 failed to fix the Host header processing. Host is not a URI but is instead defined in https://tools.ietf.org/html/rfc3986#section-3.2.2 as host = IP-literal / IPv4address / reg-name
Modifications:
- Host should not be treated as a URI.
- We should be more explicit about required fields, and unexpected input by throwing exceptions.
Result:
Translation from HTTP/1.x to HTTP/2 is more correct.