Make the handlers defined in bin/tests/system/resend_loop/ans3/ans.py
follow canonical naming conventions used in other system tests. Keep
all server initialization code in the main() function.
Since the _get_cookie() function is only used by the CookieHandler
class, make the former a method of the latter to keep related logic
close in the source code.
The "len(cookie.server) == 0" condition is superfluous for the
"resend_loop" system test, so remove it. Add a return type annotation
to the _get_cookie() function.
The "yield" keyword does not cause a function to return. By design,
get_responses() may yield multiple DNS responses in a single call. As
currently implemented, CookieHandler.get_responses() sends two responses
to each client query that does not contain a COOKIE option. Make the
logic in that method consistent with code comments by only sending one
response to every query - either SERVFAIL or BADCOOKIE, never both.
The ans3 custom server instance is created with default_aa=True. Do not
pass the authoritative=True keyword argument to the DnsResponseSend
constructor in CookieHandler.get_responses() as it is redundant.
The ans3 custom server does not have any zones defined, so the responses
passed to its handlers by core isctest.asyncserver code are guaranteed
to be empty. Remove a call to qctx.prepare_new_response() from
CookieHandler.get_responses() as it is redundant.
The RootNSHandler and ExampleNSHandler classes are only equipped to
respond to specific QNAME/QTYPE tuples, not all queries for a specific
QNAME. Turn them into subclasses of QnameQtypeHandler and make them
only respond to QTYPE=NS queries to prevent sending NS responses for
non-NS queries.
Update the resend_loop_badcookie system test to ensure there is no
attempt to resend the query using TCP when getting BADCOOKIE from an
upstream server using this transport already.
Run malicious server: resend_loop/ans3/ans.py
Start BIND: ns4
Send single query to test.example
The resolver will repeatedly resend queries until the fetch timeout
expires, resulting in resulting in thousands of qrysent while the quota
counter remains 0.
