Postgres INET contains (<<) operator search using MetasploitDataModels::IPAddress::CIDR

where.rb

attribute = Mdm::Host.arel_table[:address]

value = MetasploitDataModels::IPAddress::V4::CIDR.new(value: '1.2.3.4/8')
formatted_value = "#{value.address}/#{value.prefix_length}"
cast_argument = Arel::Nodes::As.new(formatted_value, Arel::Nodes::SqlLiteral.new('INET'))
# @see https://gist.github.com/mrpunkin/1996454
value_as_inet = Arel::Nodes::NamedFunction.new('CAST', [cast_argument])

operation = Arel::Nodes::InfixOperation.new(
  '<<',
  attribute,
  value_as_inet
)

operation.to_sql # "\"hosts\".\"address\" << CAST('1.2.3.4/8' AS INET)"

I had to read AREL's source to figure out how to do AS on a literal string, but thanks to @mrpunkin for how to use CAST in AREL.