The resolve() function hangs if the list of hosts it is resolving contains duplicate entries

[balachandrannitish]

If the list of hosts you're resolving contains duplicate entries, the resolve() function hangs/freezes causing the ADNS script itself to hang.

Steps to Reproduce:

1. duplicate_host_list = ["google.com","oracle.com","google.com"]
2. ar = AsyncResolver(duplicate_host_list)
3. resolved_hosts = ar.resolve()

The script always hangs at step 3. If you get rid of the duplicate domain (i.e. google.com) and retry this, everything works perfectly.

I modified main() in asnc_dns.py slightly to test this. This is what it looks like,

if __name__ == "__main__":
    hosts = ["google.com","oracle.com","google.com"]
    ar = AsyncResolver(hosts, intensity=500)
    start = time()
    resolved_hosts = ar.resolve()
    end = time()
    print "It took %.2f seconds to resolve %d hosts." % (end-start, len(hosts)) 

[az-z]

@balachandrannitish : thank you!
your post just saved me another day of frustration.
the bug is in the C module it seems.

[mtarbit]

I think the bug is actually in the finished_resolving function. If there are duplicates then resolved_hosts will never have as many entries as self.hosts. A simple fix might be something like this:

def finished_resolving():
    return len(resolved_hosts) == len(set(self.hosts))

Though you'd probably want to pre-calculate the number of unique hosts instead.