def format_time(self, value):
if value is None:
return u'<td>-</td>'
else:
return u'<td>%s</td>' % relative_time(value, 0, 0)
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=f_num(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
age_hdr = self.parsed_hdrs.get('age', 0)
date_hdr = self.parsed_hdrs.get('date', 0)
if date_hdr > 0:
apparent_age = max(0,
int(self.res_ts - date_hdr))
else:
apparent_age = 0
current_age = max(apparent_age, age_hdr)
current_age_str = relative_time(current_age, 0, 0)
age_str = relative_time(age_hdr, 0, 0)
self.age = age_hdr
if age_hdr >= 1:
self.setMessage('header-age header-date', rs.CURRENT_AGE,
age=age_str)
# Check for clock skew and dateless origin server.
skew = date_hdr - self.res_ts + age_hdr
if not date_hdr:
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)
elif age_hdr > max_clock_skew and current_age - skew < max_clock_skew:
self.setMessage('header-date header-age', rs.AGE_PENALTY)
elif 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)
# calculate freshness
freshness_lifetime = 0
has_explicit_freshness = False
has_cc_freshness = False
freshness_hdrs = ['header-date']
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
has_cc_freshness = True
elif 'max-age' in cc_keys:
freshness_lifetime = cc_dict['max-age']
freshness_hdrs.append('header-cache-control')
has_explicit_freshness = True
has_cc_freshness = True
elif self.parsed_hdrs.has_key('expires'):
has_explicit_freshness = True
freshness_hdrs.append('header-expires')
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.res_ts # ?
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
fresh = freshness_left > 0
if has_explicit_freshness:
if fresh:
self.setMessage(" ".join(freshness_hdrs), rs.FRESHNESS_FRESH,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age = current_age_str
)
elif has_cc_freshness and self.age > freshness_lifetime:
self.setMessage(" ".join(freshness_hdrs),
rs.FRESHNESS_STALE_CACHE,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age = current_age_str
)
else:
self.setMessage(" ".join(freshness_hdrs),
rs.FRESHNESS_STALE_ALREADY,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age = current_age_str
)
# can heuristic freshness be used?
elif self.res_status in heuristic_cacheable_status:
self.setMessage('header-last-modified', rs.FRESHNESS_HEURISTIC)
else:
self.setMessage('', rs.FRESHNESS_NONE)
# can stale responses be served?
if 'must-revalidate' in cc_keys:
if fresh:
self.setMessage('header-cache-control',
rs.FRESH_MUST_REVALIDATE
)
elif has_explicit_freshness:
self.setMessage('header-cache-control',
rs.STALE_MUST_REVALIDATE
)
elif 'proxy-revalidate' in cc_keys or 's-maxage' in cc_keys:
if fresh:
self.setMessage('header-cache-control',
rs.FRESH_PROXY_REVALIDATE
)
elif has_explicit_freshness:
self.setMessage('header-cache-control',
rs.STALE_PROXY_REVALIDATE
)
else:
if fresh:
self.setMessage('header-cache-control', rs.FRESH_SERVABLE)
elif has_explicit_freshness:
self.setMessage('header-cache-control', rs.STALE_SERVABLE)
# public?
if 'public' in cc_keys: # TODO: check for authentication in request
self.setMessage('header-cache-control', rs.PUBLIC)
