Is it acceptable to have empty header in HTTP? By empty i mean ":" no header name and no header value. The same question is also relvant to HTTP2 (suppose it is the same answer but to be sure).
Thanks.
HTTP defines a header field as:
header-field = field-name ":" OWS field-value OWS
field-name = token
field-value = *( field-content / obs-fold )
field-content = field-vchar [ 1*( SP / HTAB ) field-vchar ]
field-vchar = VCHAR / obs-text
obs-fold = CRLF 1*( SP / HTAB )
; obsolete line folding
; see Section 3.2.4
The token part is later on defined as:
token = 1*tchar
tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*"
/ "+" / "-" / "." / "^" / "_" / "`" / "|" / "~"
/ DIGIT / ALPHA
; any VCHAR, except delimiters
The implication is that the header name must be at least 1 byte, and the value can be 0 or more characters.
HTTP/2 uses the same underlying data-model.