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# A header used to correlate requests and responses
state_header = b"content-language"
# Static ETag to use (and expect)
etag = b"abcdef"
def error(msg):
return (299, u"Client Error"), [
(b'content-type', b'text/plain'),
(b'access-control-allow-origin', b"*"),
(b'access-control-expose-headers', state_header),
(b'cache-control', b'no-store')
], msg
def main(request, response):
headers = []
inm = request.headers.get(b'if-none-match', None)
raw_req_num = request.headers.get(state_header, None)
if raw_req_num == None:
return error(u"no req_num header in request")
req_num = int(raw_req_num)
if req_num > 8:
return error(u"req_num %s out of range" % req_num)
headers.append((b"Access-Control-Expose-Headers", state_header))
headers.append((state_header, req_num))
headers.append((b"A", req_num))
headers.append((b"B", req_num))
if req_num % 2: # odd requests are the first in a test pair
if inm:
# what are you doing here? This should be a fresh request.
return error(u"If-None-Match on first request")
status = 200, b"OK"
headers.append((b"Access-Control-Allow-Origin", b"*"))
headers.append((b"Content-Type", b"text/plain"))
headers.append((b"Cache-Control", b"private, max-age=3, must-revalidate"))
headers.append((b"ETag", etag))
return status, headers, b"Success"
else: # even requests are the second in a pair, and should have a good INM.
if inm != etag:
# Bad browser.
if inm == None:
return error(u"If-None-Match missing")
return error(u"If-None-Match '%s' mismatches")
if req_num == 2:
pass # basic, vanilla check
elif req_num == 4:
headers.append((b"Access-Control-Expose-Headers", b"a, b"))
elif req_num == 6:
headers.append((b"Access-Control-Expose-Headers", b"a"))
elif req_num == 8:
headers.append((b"Access-Control-Allow-Origin", b"other.origin.example:80"))
status = 304, b"Not Modified"
return status, headers, b""