UdpBuilder.reuse_address does not work on OS X

[oyiptong]

UdpBuilder.reuse_address seems to work fine on Linux but not on OS X

[alexcrichton]

Maybe this option just isn't supported on OSX? What's the error you're seeing?

[oyiptong]

The only error i see on OS X is "address in use".

Digging further into this, I tried to use SO_REUSEPORT and that seems to work on OS X. Perhaps SO_REUSEADDR isn't supported by Darwin?

[alexcrichton]

Perhaps? I forget the specifics here of how cross platform this API is...

[DoumanAsh]

@oyiptong it depends on how to interpret you these options

SO_REUSEADDR

Indicates that the rules used in validating addresses supplied
in a bind(2) call should allow reuse of local addresses. For
AF_INET sockets this means that a socket may bind, except when
there is an active listening socket bound to the address.

In short: if you bind "192.168.0.1:21", and another socket attempts to bind to "0.0.0.0:21" it will fail without option

SO_REUSEPORT

Permits multiple AF_INET or AF_INET6 sockets to be bound to an
identical socket address. This option must be set on each
socket (including the first socket) prior to calling bind(2)
on the socket. To prevent port hijacking, all of the
processes binding to the same address must have the same
effective UID. This option can be employed with both TCP and
UDP sockets.

In short: you can bind to the SAME address as much sockets, as you want as long as they all have this option set.

P.s. see http://stackoverflow.com/questions/14388706/socket-options-so-reuseaddr-and-so-reuseport-how-do-they-differ-do-they-mean-t