def format_time(value: float) -> str:
if value is None:
return '<td>-</td>'
return '<td>%s</td>' % relative_time(value, 0, 0)
def checkCaching(response: HttpResponse, request: HttpRequest = None) -> None:
"Examine HTTP caching characteristics."
# get header values
lm_hdr = response.parsed_headers.get("last-modified", None)
date_hdr = response.parsed_headers.get("date", None)
expires_hdr = response.parsed_headers.get("expires", None)
etag_hdr = response.parsed_headers.get("etag", None)
age_hdr = response.parsed_headers.get("age", None)
cc_set = response.parsed_headers.get("cache-control", [])
cc_list = [k for (k, v) in cc_set]
cc_dict = dict(cc_set)
cc_keys = list(cc_dict.keys())
# Last-Modified
if lm_hdr:
serv_date = date_hdr or response.start_time
if lm_hdr > serv_date:
response.add_note("header-last-modified", LM_FUTURE)
else:
response.add_note(
"header-last-modified",
LM_PRESENT,
last_modified_string=relative_time(lm_hdr, serv_date),
)
# 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",
]
# 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():
response.add_note("header-cache-control",
CC_MISCAP,
cc_lower=cc.lower(),
cc=cc)
if cc in known_cc and cc_list.count(cc) > 1:
response.add_note("header-cache-control", CC_DUP, cc=cc)
# Who can store this?
if request and request.method not in cacheable_methods:
response.store_shared = response.store_private = False
request.add_note("method", METHOD_UNCACHEABLE, method=request.method)
return # bail; nothing else to see here
if "no-store" in cc_keys:
response.store_shared = response.store_private = False
response.add_note("header-cache-control", NO_STORE)
return # bail; nothing else to see here
if "private" in cc_keys:
response.store_shared = False
response.store_private = True
response.add_note("header-cache-control", PRIVATE_CC)
elif (request
and "authorization" in [k.lower() for k, v in request.headers]
and "public" not in cc_keys):
response.store_shared = False
response.store_private = True
response.add_note("header-cache-control", PRIVATE_AUTH)
else:
response.store_shared = response.store_private = True
response.add_note("header-cache-control", STOREABLE)
# no-cache?
if "no-cache" in cc_keys:
if lm_hdr is None and etag_hdr is None:
response.add_note("header-cache-control", NO_CACHE_NO_VALIDATOR)
else:
response.add_note("header-cache-control", 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:
response.add_note("header-cache-control", 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:
response.add_note("header-cache-control", CHECK_NOT_INTEGER)
if pre_check is not None and post_check is not None:
if pre_check == 0 and post_check == 0:
response.add_note("header-cache-control", CHECK_ALL_ZERO)
elif post_check > pre_check:
response.add_note("header-cache-control",
CHECK_POST_BIGGER)
post_check = pre_check
elif post_check == 0:
response.add_note("header-cache-control", CHECK_POST_ZERO)
else:
response.add_note(
"header-cache-control",
CHECK_POST_PRE,
pre_check=pre_check,
post_check=post_check,
)
# vary?
vary = response.parsed_headers.get("vary", set())
if "*" in vary:
response.add_note("header-vary", VARY_ASTERISK)
return # bail; nothing else to see here
if len(vary) > 3:
response.add_note("header-vary",
VARY_COMPLEX,
vary_count=f_num(len(vary)))
else:
if "user-agent" in vary:
response.add_note("header-vary", VARY_USER_AGENT)
if "host" in vary:
response.add_note("header-vary", VARY_HOST)
# calculate age
response.age = age_hdr or 0
age_str = relative_time(response.age, 0, 0)
if date_hdr and date_hdr > 0:
apparent_age = max(0, int(response.start_time - date_hdr))
else:
apparent_age = 0
current_age = max(apparent_age, response.age)
current_age_str = relative_time(current_age, 0, 0)
if response.age >= 1:
response.add_note("header-age header-date", CURRENT_AGE, age=age_str)
# Check for clock skew and dateless origin server.
if not date_hdr:
response.add_note("", DATE_CLOCKLESS)
if expires_hdr or lm_hdr:
response.add_note("header-expires header-last-modified",
DATE_CLOCKLESS_BAD_HDR)
else:
skew = date_hdr - response.start_time + (response.age)
if response.age > max_clock_skew and (current_age -
skew) < max_clock_skew:
response.add_note("header-date header-age", AGE_PENALTY)
elif abs(skew) > max_clock_skew:
response.add_note(
"header-date",
DATE_INCORRECT,
clock_skew_string=relative_time(skew, 0, 2),
)
else:
response.add_note("header-date", 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:
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 "expires" in response.parsed_headers:
# An invalid Expires header means it's automatically stale
has_explicit_freshness = True
freshness_hdrs.append("header-expires")
freshness_lifetime = (expires_hdr or 0) - (date_hdr
or int(response.start_time))
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)
response.freshness_lifetime = freshness_lifetime
fresh = freshness_left > 0
if has_explicit_freshness:
if fresh:
response.add_note(
" ".join(freshness_hdrs),
FRESHNESS_FRESH,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age=current_age_str,
)
elif has_cc_freshness and response.age > freshness_lifetime:
response.add_note(
" ".join(freshness_hdrs),
FRESHNESS_STALE_CACHE,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age=current_age_str,
)
else:
response.add_note(
" ".join(freshness_hdrs),
FRESHNESS_STALE_ALREADY,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age=current_age_str,
)
# can heuristic freshness be used?
elif response.status_code in heuristic_cacheable_status:
response.add_note("header-last-modified", FRESHNESS_HEURISTIC)
else:
response.add_note("", FRESHNESS_NONE)
# can stale responses be served?
if "must-revalidate" in cc_keys:
if fresh:
response.add_note("header-cache-control", FRESH_MUST_REVALIDATE)
elif has_explicit_freshness:
response.add_note("header-cache-control", STALE_MUST_REVALIDATE)
elif "proxy-revalidate" in cc_keys or "s-maxage" in cc_keys:
if fresh:
response.add_note("header-cache-control", FRESH_PROXY_REVALIDATE)
elif has_explicit_freshness:
response.add_note("header-cache-control", STALE_PROXY_REVALIDATE)
else:
if fresh:
response.add_note("header-cache-control", FRESH_SERVABLE)
elif has_explicit_freshness:
response.add_note("header-cache-control", STALE_SERVABLE)
# public?
if "public" in cc_keys: # TODO: check for authentication in request
response.add_note("header-cache-control", PUBLIC)
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(response: HttpResponse, request: HttpRequest=None) -> None:
"Examine HTTP caching characteristics."
# get header values
lm_hdr = response.parsed_headers.get('last-modified', None)
date_hdr = response.parsed_headers.get('date', None)
expires_hdr = response.parsed_headers.get('expires', None)
etag_hdr = response.parsed_headers.get('etag', None)
age_hdr = response.parsed_headers.get('age', None)
cc_set = response.parsed_headers.get('cache-control', [])
cc_list = [k for (k, v) in cc_set]
cc_dict = dict(cc_set)
cc_keys = list(cc_dict.keys())
# Last-Modified
if lm_hdr:
serv_date = date_hdr or response.start_time
if lm_hdr > serv_date:
response.add_note('header-last-modified', LM_FUTURE)
else:
response.add_note('header-last-modified', LM_PRESENT,
last_modified_string=relative_time(lm_hdr, serv_date))
# 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"]
# 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():
response.add_note('header-cache-control', CC_MISCAP,
cc_lower=cc.lower(), cc=cc)
if cc in known_cc and cc_list.count(cc) > 1:
response.add_note('header-cache-control', CC_DUP, cc=cc)
# Who can store this?
if request and request.method not in cacheable_methods:
response.store_shared = response.store_private = False
request.add_note('method', METHOD_UNCACHEABLE, method=request.method)
return # bail; nothing else to see here
elif 'no-store' in cc_keys:
response.store_shared = response.store_private = False
response.add_note('header-cache-control', NO_STORE)
return # bail; nothing else to see here
elif 'private' in cc_keys:
response.store_shared = False
response.store_private = True
response.add_note('header-cache-control', PRIVATE_CC)
elif request and 'authorization' in [k.lower() for k, v in request.headers] \
and 'public' not in cc_keys:
response.store_shared = False
response.store_private = True
response.add_note('header-cache-control', PRIVATE_AUTH)
else:
response.store_shared = response.store_private = True
response.add_note('header-cache-control', STOREABLE)
# no-cache?
if 'no-cache' in cc_keys:
if lm_hdr is None and etag_hdr is None:
response.add_note('header-cache-control', NO_CACHE_NO_VALIDATOR)
else:
response.add_note('header-cache-control', 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:
response.add_note('header-cache-control', 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:
response.add_note('header-cache-control', CHECK_NOT_INTEGER)
if pre_check is not None and post_check is not None:
if pre_check == 0 and post_check == 0:
response.add_note('header-cache-control', CHECK_ALL_ZERO)
elif post_check > pre_check:
response.add_note('header-cache-control', CHECK_POST_BIGGER)
post_check = pre_check
elif post_check == 0:
response.add_note('header-cache-control', CHECK_POST_ZERO)
else:
response.add_note('header-cache-control', CHECK_POST_PRE,
pre_check=pre_check, post_check=post_check)
# vary?
vary = response.parsed_headers.get('vary', set())
if "*" in vary:
response.add_note('header-vary', VARY_ASTERISK)
return # bail; nothing else to see here
elif len(vary) > 3:
response.add_note('header-vary', VARY_COMPLEX, vary_count=f_num(len(vary)))
else:
if "user-agent" in vary:
response.add_note('header-vary', VARY_USER_AGENT)
if "host" in vary:
response.add_note('header-vary', VARY_HOST)
# TODO: enumerate the axes in a message
# calculate age
response.age = age_hdr or 0
age_str = relative_time(response.age, 0, 0)
if date_hdr and date_hdr > 0:
apparent_age = max(0, int(response.start_time - date_hdr))
else:
apparent_age = 0
current_age = max(apparent_age, response.age)
current_age_str = relative_time(current_age, 0, 0)
if response.age >= 1:
response.add_note('header-age header-date', CURRENT_AGE, age=age_str)
# Check for clock skew and dateless origin server.
if not date_hdr:
response.add_note('', DATE_CLOCKLESS)
if expires_hdr or lm_hdr:
response.add_note('header-expires header-last-modified', DATE_CLOCKLESS_BAD_HDR)
else:
skew = date_hdr - response.start_time + (response.age)
if response.age > max_clock_skew and (current_age - skew) < max_clock_skew:
response.add_note('header-date header-age', AGE_PENALTY)
elif abs(skew) > max_clock_skew:
response.add_note('header-date', DATE_INCORRECT,
clock_skew_string=relative_time(skew, 0, 2))
else:
response.add_note('header-date', 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:
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 'expires' in response.parsed_headers:
# An invalid Expires header means it's automatically stale
has_explicit_freshness = True
freshness_hdrs.append('header-expires')
freshness_lifetime = (expires_hdr or 0) - (date_hdr or response.start_time)
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)
response.freshness_lifetime = freshness_lifetime
fresh = freshness_left > 0
if has_explicit_freshness:
if fresh:
response.add_note(" ".join(freshness_hdrs), FRESHNESS_FRESH,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age=current_age_str)
# FIXME: response.age = None
elif has_cc_freshness and response.age > freshness_lifetime:
response.add_note(" ".join(freshness_hdrs), FRESHNESS_STALE_CACHE,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age=current_age_str)
else:
response.add_note(" ".join(freshness_hdrs), FRESHNESS_STALE_ALREADY,
freshness_lifetime=freshness_lifetime_str,
freshness_left=freshness_left_str,
current_age=current_age_str)
# can heuristic freshness be used?
elif response.status_code in heuristic_cacheable_status:
response.add_note('header-last-modified', FRESHNESS_HEURISTIC)
else:
response.add_note('', FRESHNESS_NONE)
# can stale responses be served?
if 'must-revalidate' in cc_keys:
if fresh:
response.add_note('header-cache-control', FRESH_MUST_REVALIDATE)
elif has_explicit_freshness:
response.add_note('header-cache-control', STALE_MUST_REVALIDATE)
elif 'proxy-revalidate' in cc_keys or 's-maxage' in cc_keys:
if fresh:
response.add_note('header-cache-control', FRESH_PROXY_REVALIDATE)
elif has_explicit_freshness:
response.add_note('header-cache-control', STALE_PROXY_REVALIDATE)
else:
if fresh:
response.add_note('header-cache-control', FRESH_SERVABLE)
elif has_explicit_freshness:
response.add_note('header-cache-control', STALE_SERVABLE)
# public?
if 'public' in cc_keys: # TODO: check for authentication in request
response.add_note('header-cache-control', PUBLIC)
def format_time(value: float) -> str:
if value is None:
return '<td>-</td>'
else:
return '<td>%s</td>' % relative_time(value, 0, 0)
def format_time(value: float) -> str:
if value is None:
return "<td>-</td>"
return "<td>%s</td>" % relative_time(value, 0, 0)
