Protocol names can only be on the left hand side of filter expressions.
Commit ac0b1d42f3 (merge !4214) caused
unquoted strings that could be interpreted as either protocol names or
byte arrays to be parsed as the latter when on the RHS. Further
relax by allowing unquoted strings on the RHS that can be interpreted as
protocol names to be treated as any generic unquoted string. (The
semantic checker will still prefer interpreting the string as a byte
array, if possible, to a generic string.)
This is useful for filter expressions of the sort "frame contains data",
where data should be interpreted as "data", i.e. "\x64\x61\x74\x61".
Long run this ideally should be fixed earlier, at the lex parser or
grammar checker.
a2120e823c