[erlang-questions] connect to existing unix socket

[Joe K]

tl;dr

How can I avoid:

```
1> gen_udp:open(0, [binary, {ip, {local, <<"/home/vagrant/janus.sock">>}}]).
{error,eaddrinuse}
```

---

I have a janus gateway (https://github.com/meetecho/janus-gateway) running on the same host as my Erlang app and I want to be able to make them talk via a unix socket. Janus creates a SOCK_SEQPACKET or SOCK_DGRAM unix socket on startup and I want to be able to connect to it from Erlang. The problem is, when I set Janus to use SOCK_DGRAM, I can't then open it from Erlang:

```
1> gen_udp:open(0, [binary, {ip, {local, <<"/home/vagrant/janus.sock">>}}]).
{error,eaddrinuse}
```

and if I set Janus to use SOCK_SEQPACKET, gen_tcp fails for me as well:

```
2> gen_tcp:connect({local, <<"/home/vagrant/janus.sock">>}, 0, [local]).
{error,eprototype}
```

What am I doing wrong?