Retrieve client IP in :ranch

Question

I'm using :ranch to receive TCP packges in my Phoenix application.

First I created a listener in the server using:

:ranch.start_listener(tcp_echo, ranch_tcp, [{port, 5555}], echo_protocol, [] )

How could I print the client IP in the echo_protocol ?

Answer 1

Ranch includes a sample echo application .

In echo_protocol.erl , there's an init function that accepts the connection from the client:

init(Ref, Socket, Transport, _Opts = []) ->
    ok = ranch:accept_ack(Ref),
    loop(Socket, Transport).

You can display the client ip address there:

init(Ref, Socket, Transport, _Opts = []) ->
    ok = ranch:accept_ack(Ref),
    {ok, {IpAddress, _}} = inet:peername(Socket),
    io:format("Client ~p~n", [IpAddress]),
    loop(Socket, Transport).

It will appear in a format like:

Client {127,0,0,1}