def checkClock(self):
"Check for clock skew and dateless origin server."
if not self.parsed_hdrs.has_key('date'):
self.setMessage('', rs.DATE_CLOCKLESS)
if self.parsed_hdrs.has_key('expires') or \
self.parsed_hdrs.has_key('last-modified'):
self.setMessage('header-expires header-last-modified', rs.DATE_CLOCKLESS_BAD_HDR)
return
skew = self.parsed_hdrs['date'] - \
self.timestamp + self.parsed_hdrs.get('age', 0)
if abs(skew) > max_clock_skew:
self.setMessage('header-date', rs.DATE_INCORRECT,
clock_skew_string=relative_time(skew, 0, 2)
)
else:
self.setMessage('header-date', rs.DATE_CORRECT)
def checkCaching(self):
"Examine HTTP caching characteristics."
# TODO: check URI for query string, message about HTTP/1.0 if so
# known Cache-Control directives that don't allow duplicates
known_cc = ["max-age", "no-store", "s-maxage", "public", "private"
"pre-check", "post-check", "stale-while-revalidate", "stale-if-error",
]
cc_set = self.parsed_hdrs.get('cache-control', [])
cc_list = [k for (k,v) in cc_set]
cc_dict = dict(cc_set)
cc_keys = cc_dict.keys()
# check for mis-capitalised directives /
# assure there aren't any dup directives with different values
for cc in cc_keys:
if cc.lower() in known_cc and cc != cc.lower():
self.setMessage('header-cache-control', rs.CC_MISCAP,
cc_lower = cc.lower(), cc=cc
)
if cc in known_cc and cc_list.count(cc) > 1:
self.setMessage('header-cache-control', rs.CC_DUP,
cc=cc
)
# Who can store this?
if self.method not in cacheable_methods:
self.store_shared = self.store_private = False
self.setMessage('method', rs.METHOD_UNCACHEABLE, method=self.method)
return # bail; nothing else to see here
elif 'no-store' in cc_keys:
self.store_shared = self.store_private = False
self.setMessage('header-cache-control', rs.NO_STORE)
return # bail; nothing else to see here
elif 'private' in cc_keys:
self.store_shared = False
self.store_private = True
self.setMessage('header-cache-control', rs.PRIVATE_CC)
elif 'authorization' in [k.lower() for k, v in self.req_hdrs] and \
not 'public' in cc_keys:
self.store_shared = False
self.store_private = True
self.setMessage('header-cache-control', rs.PRIVATE_AUTH)
else:
self.store_shared = self.store_private = True
self.setMessage('header-cache-control', rs.STOREABLE)
# no-cache?
if 'no-cache' in cc_keys:
if "last-modified" not in self.parsed_hdrs.keys() and \
"etag" not in self.parsed_hdrs.keys():
self.setMessage('header-cache-control', rs.NO_CACHE_NO_VALIDATOR)
else:
self.setMessage('header-cache-control', rs.NO_CACHE)
return
# pre-check / post-check
if 'pre-check' in cc_keys or 'post-check' in cc_keys:
if 'pre-check' not in cc_keys or 'post_check' not in cc_keys:
self.setMessage('header-cache-control', rs.CHECK_SINGLE)
else:
pre_check = post_check = None
try:
pre_check = int(cc_dict['pre-check'])
post_check = int(cc_dict['post-check'])
except ValueError:
self.setMessage('header-cache-control', rs.CHECK_NOT_INTEGER)
if pre_check is not None and post_check is not None:
if pre_check == 0 and post_check == 0:
self.setMessage('header-cache-control', rs.CHECK_ALL_ZERO)
elif post_check > pre_check:
self.setMessage('header-cache-control', rs.CHECK_POST_BIGGER)
post_check = pre_check
elif post_check == 0:
self.setMessage('header-cache-control', rs.CHECK_POST_ZERO)
else:
self.setMessage('header-cache-control', rs.CHECK_POST_PRE,
pre_check=pre_check, post_check=post_check)
# vary?
vary = self.parsed_hdrs.get('vary', set())
if "*" in vary:
self.setMessage('header-vary', rs.VARY_ASTERISK)
return # bail; nothing else to see here
elif len(vary) > 3:
self.setMessage('header-vary', rs.VARY_COMPLEX, vary_count=len(vary))
else:
if "user-agent" in vary:
self.setMessage('header-vary', rs.VARY_USER_AGENT)
if "host" in vary:
self.setMessage('header-vary', rs.VARY_HOST)
# TODO: enumerate the axes in a message
# calculate age
if self.parsed_hdrs.has_key('date'):
apparent_age = max(0,
int(self.timestamp - self.parsed_hdrs['date']))
else:
apparent_age = 0
age = self.parsed_hdrs.get('age', 0)
current_age = max(apparent_age, self.parsed_hdrs.get('age', 0))
current_age_str = relative_time(current_age, 0, 0)
self.age = age
if age >= 1:
self.setMessage('header-age header-date', rs.CURRENT_AGE,
current_age=current_age_str)
# calculate freshness
freshness_lifetime = 0
has_explicit_freshness = False
freshness_hdrs = ['header-date', 'header-expires']
if 's-maxage' in cc_keys: # TODO: differentiate message for s-maxage
freshness_lifetime = cc_dict['s-maxage']
freshness_hdrs.append('header-cache-control')
has_explicit_freshness = True
elif 'max-age' in cc_keys:
freshness_lifetime = cc_dict['max-age']
freshness_hdrs.append('header-cache-control')
has_explicit_freshness = True
elif self.parsed_hdrs.has_key('expires'):
has_explicit_freshness = True
if self.parsed_hdrs.has_key('date'):
freshness_lifetime = self.parsed_hdrs['expires'] - \
self.parsed_hdrs['date']
else:
freshness_lifetime = self.parsed_hdrs['expires'] - \
self.timestamp # ?
freshness_left = freshness_lifetime - current_age
freshness_left_str = relative_time(abs(int(freshness_left)), 0, 0)
freshness_lifetime_str = relative_time(int(freshness_lifetime), 0, 0)
self.freshness_lifetime = freshness_lifetime
if freshness_left > 0:
self.setMessage(" ".join(freshness_hdrs), rs.FRESHNESS_FRESH,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age = current_age_str
)
else:
self.setMessage(" ".join(freshness_hdrs), rs.FRESHNESS_STALE,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age = current_age_str
)
# can heuristic freshness be used?
if self.res_status in heuristic_cacheable_status and \
not has_explicit_freshness:
self.setMessage('header-last-modified', rs.HEURISTIC_FRESHNESS)
# can stale responses be served?
if 'must-revalidate' in cc_keys:
self.stale_serveable = False
self.setMessage('header-cache-control', rs.STALE_MUST_REVALIDATE)
elif 'proxy-revalidate' in cc_keys or 's-maxage' in cc_keys:
self.stale_serveable = False
self.setMessage('header-cache-control', rs.STALE_PROXY_REVALIDATE)
else:
self.stale_serveable = True
self.setMessage('header-cache-control', rs.STALE_SERVABLE)
# public?
if 'public' in cc_keys:
self.setMessage('header-cache-control', rs.PUBLIC)
