tree cd820dadf75138e2f98f4d8fa709a436db5844b8
parent 4e49ba9a9603d457e8556063a8a6dda475d37288
author David Crawshaw <crawshaw@google.com> 1495219933 -0400
committer David Crawshaw <crawshaw@google.com> 1495223221 -0400

dns: close endpoint when no longer needed

Keeping the old endpoint open on a UDP connection meant that a future
endpoint would not pick up new configuration from a DHCP change. This
meant an existing getaddrinfo would wait for its timeout if a DHCP IP
address appeared in the middle of its attempts.

Closing the endpoint after each attempt means the next one will try
the new, better path and actually succeed.

In practice, this means if `wget http://www.google.com` is stuck on
getaddrinfo before a DHCP IP has been picked up, it will now wait the
3 second timeout and on the next attempt succeed, instead of blocking
for a long time.

NET-77 # done

Change-Id: Ie945685b12d24862ba6ac562830ca9a72d39d513