t.n.common.extractRecord ineffectually checks for socket.inet_ntop

	@twm reported
Trac ID	trac#9753
Type	defect
Created	2020-01-08 04:39:47Z

From twisted.names.common.extractRecord():

    if hasattr(socket, 'inet_ntop'):
        for r in answers:
            if r.name == name and r.type == dns.A6:
                return socket.inet_ntop(socket.AF_INET6, r.payload.address)
        for r in answers:
            if r.name == name and r.type == dns.AAAA:
                return socket.inet_ntop(socket.AF_INET6, r.payload.address)
    for r in answers:
        if r.name == name and r.type == dns.A:
            return socket.inet_ntop(socket.AF_INET, r.payload.address)

The hasattr() check is ineffectual for two reasons:

1. twisted.python.compat monkeypatches this method, so it is always present.
2. The processing of A records uses this function outside the block protected by the check.

Remove the check.

trac-id__9753 9753
type__defect defect
reporter__twm twm
priority__low low
milestone__None None
branch__ 
branch_author__ 
status__new new
resolution__None None
component__names names
keywords__None None
time__1578458387989425 1578458387989425
changetime__1578458387989425 1578458387989425
version__None None
owner__None None

Start at twisted.names.common.extractRecord(), where the issue identifies the ineffective socket.inet_ntop check. Remove that check, then inspect the existing tests covering A, A6, and AAAA records to verify the lookup behavior remains correct.