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module ActionDispatch
module Http
module Cache
module Request
HTTP_IF_MODIFIED_SINCE = 'HTTP_IF_MODIFIED_SINCE'.freeze
HTTP_IF_NONE_MATCH = 'HTTP_IF_NONE_MATCH'.freeze
def if_modified_since
if since = get_header(HTTP_IF_MODIFIED_SINCE)
Time.rfc2822(since) rescue nil
end
end
def if_none_match
get_header HTTP_IF_NONE_MATCH
end
def if_none_match_etags
(if_none_match ? if_none_match.split(/\s*,\s*/) : []).collect do |etag|
etag.gsub(/^\"|\"$/, "")
end
end
def not_modified?(modified_at)
if_modified_since && modified_at && if_modified_since >= modified_at
end
def etag_matches?(etag)
if etag
etag = etag.gsub(/^\"|\"$/, "")
if_none_match_etags.include?(etag)
end
end
# Check response freshness (Last-Modified and ETag) against request
# If-Modified-Since and If-None-Match conditions. If both headers are
# supplied, both must match, or the request is not considered fresh.
def fresh?(response)
last_modified = if_modified_since
etag = if_none_match
return false unless last_modified || etag
success = true
success &&= not_modified?(response.last_modified) if last_modified
success &&= etag_matches?(response.etag) if etag
success
end
end
module Response
attr_reader :cache_control
def last_modified
if last = get_header(LAST_MODIFIED)
Time.httpdate(last)
end
end
def last_modified?
has_header? LAST_MODIFIED
end
def last_modified=(utc_time)
set_header LAST_MODIFIED, utc_time.httpdate
end
def date
if date_header = get_header(DATE)
Time.httpdate(date_header)
end
end
def date?
has_header? DATE
end
def date=(utc_time)
set_header DATE, utc_time.httpdate
end
# This method allows you to set the ETag for cached content, which
# will be returned to the end user.
#
# By default, Action Dispatch sets all ETags to be weak.
# This ensures that if the content changes only semantically,
# the whole page doesn't have to be regenerated from scratch
# by the web server. With strong ETags, pages are compared
# byte by byte, and are regenerated only if they are not exactly equal.
def etag=(etag)
key = ActiveSupport::Cache.expand_cache_key(etag)
super %(W/"#{Digest::MD5.hexdigest(key)}")
end
def etag?; etag; end
private
DATE = 'Date'.freeze
LAST_MODIFIED = "Last-Modified".freeze
SPECIAL_KEYS = Set.new(%w[extras no-cache max-age public private must-revalidate])
def cache_control_segments
if cache_control = _cache_control
cache_control.delete(' ').split(',')
else
[]
end
end
def cache_control_headers
cache_control = {}
cache_control_segments.each do |segment|
directive, argument = segment.split('=', 2)
if SPECIAL_KEYS.include? directive
key = directive.tr('-', '_')
cache_control[key.to_sym] = argument || true
else
cache_control[:extras] ||= []
cache_control[:extras] << segment
end
end
cache_control
end
def prepare_cache_control!
@cache_control = cache_control_headers
end
def handle_conditional_get!
if etag? || last_modified? || !@cache_control.empty?
set_conditional_cache_control!(@cache_control)
end
end
DEFAULT_CACHE_CONTROL = "max-age=0, private, must-revalidate".freeze
NO_CACHE = "no-cache".freeze
PUBLIC = "public".freeze
PRIVATE = "private".freeze
MUST_REVALIDATE = "must-revalidate".freeze
def set_conditional_cache_control!(cache_control)
control = {}
cc_headers = cache_control_headers
if extras = cc_headers.delete(:extras)
cache_control[:extras] ||= []
cache_control[:extras] += extras
cache_control[:extras].uniq!
end
control.merge! cc_headers
control.merge! cache_control
if control.empty?
self._cache_control = DEFAULT_CACHE_CONTROL
elsif control[:no_cache]
self._cache_control = NO_CACHE
if control[:extras]
self._cache_control = _cache_control + ", #{control[:extras].join(', ')}"
end
else
extras = control[:extras]
max_age = control[:max_age]
options = []
options << "max-age=#{max_age.to_i}" if max_age
options << (control[:public] ? PUBLIC : PRIVATE)
options << MUST_REVALIDATE if control[:must_revalidate]
options.concat(extras) if extras
self._cache_control = options.join(", ")
end
end
end
end
end
end
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