How do you asynchronously resolve host names to IP addresses?

Question

How do you asynchronously resolve host names to IP addresses, preferably with overlapped I/O? GetAddrInfoEx does not support overlapped I/O in Windows 7 and earlier.

I am using native C++.

score 2 · Accepted Answer · answered Apr 22 '14 at 09:02

For the record, this can be done natively on Windows 7, like this:

DnsWriteQuestionToBuffer to compose DNS queries yourself for sending.
DnsExtractRecordsFromMessage to parse DNS responses yourself after receiving.
WSASendTo in conjunction with WSARecvFrom in a IOCP server for async sending and receiving of DNS queries.

The side effect of this technique is that it's by no means a feat for a novice to easily pull.

score 2 · Answer 2 · answered Mar 19 '12 at 16:59

2

libunbound has an asynchronous resolver in it.

answered Mar 19 '12 at 16:59

Alnitak

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Thanks, but I'd rather not use a whole external library for a small function. – Joshua Apr 08 '12 at 16:57
@Joshua if you believe that DNS resolution is a "small" function then you are seriously mistaken. – Alnitak Apr 08 '12 at 19:52
Sorry, I'm a novice programmer, I kind of assumed it's simple because I thought it's a simple lookup call to a DNS server. Nevertheless, it'd be awesome if I could keep this native, as I also want to learn more about Windows networking. – Joshua Apr 09 '12 at 04:44

How do you asynchronously resolve host names to IP addresses?

2 Answers2