How to get Ephemeral port for UDP in Erlang?

Question

I'm trying to find a way to open an ephemeral port ( https://en.wikipedia.org/wiki/Ephemeral_port basic one without having to provide a specific port number, and from the ephemeral range of ports). This is for client requests via UDP protocol. I know how to open a specific port for UDP communications via:

{ok,Socket} = gen_udp:open(8000).

But prefer not to have to know an available port number ahead of time and just have the system provide one if this is even possible. Any suggestion or thought of how best to do this in Erlang?

Answer 1

Do it the same way you would in C: specify port 0.

1> {ok, S1} = gen_udp:open(0).
{ok,#Port<0.541>}
2> {ok, S2} = gen_udp:open(0).
{ok,#Port<0.547>}
3> {ok, S3} = gen_udp:open(0).
{ok,#Port<0.548>}
4> inet:port(S1).
{ok,55398}
5> inet:port(S2).
{ok,44963}
6> inet:port(S3).
{ok,58993}