Module: Tep::Cache

Defined in:
lib/tep/cache.rb

Class Method Summary collapse

Class Method Details

.not_modified?(req, res) ⇒ Boolean

True iff ‘req`’s precondition says the client’s cached copy of ‘res` is still fresh (=> answer 304). Safe methods (GET/HEAD) only.

Returns:

  • (Boolean) 


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# File 'lib/tep/cache.rb', line 11

def self.not_modified?(req, res)
  v = req.verb
  if v != "GET" && v != "HEAD"
    return false
  end

  # ETag / If-None-Match. `*` matches anything; otherwise the quoted
  # tag is matched as a substring so a comma-separated list of tags
  # in If-None-Match works.
  etag = res.headers["ETag"]
  if etag.length > 0
    inm = req.headers["if-none-match"]
    if inm.length > 0
      if inm == "*"
        return true
      end
      if Tep.str_find(inm, etag, 0) >= 0
        return true
      end
    end
  end

  # Last-Modified / If-Modified-Since: fresh if our copy is no newer
  # than the client's cached date.
  lm = res.lastmod_epoch
  if lm > 0
    ims = req.headers["if-modified-since"]
    if ims.length > 0
      ims_epoch = Sock.sphttp_parse_http_date(ims)
      if ims_epoch >= 0 && lm <= ims_epoch
        return true
      end
    end
  end

  false
end