int nn_device (int s1, int s2);
Starts a device to forward messages between two sockets. If both sockets are valid, nn_device function loops and sends any messages received from s1 to s2 and vice versa. If only one socket is valid and the other is negative, nn_device works in a "loopback" mode — it loops and sends any messages received from the socket back to itself.
To break the loop and make nn_device function exit use the nn_term(3) function.
The function loops until it hits an error. In such a case it returns -1 and sets errno to one of the values defined below.
One of the provided sockets is invalid.
Either one of the socket is not an AF_SP_RAW socket; or the two sockets don’t belong to the same protocol; or the directionality of the sockets doesn’t fit (e.g. attempt to join two SINK sockets to form a device).
The operation was interrupted by delivery of a signal.
The library is terminating.
int s1 = nn_socket (AF_SP_RAW, NN_REQ); nn_bind (s1, "tcp://127.0.0.1:5555"); int s2 = nn_socket (AF_SP_RAW, NN_REP); nn_bind (s2, "tcp://127.0.0.1:5556"); nn_device (s1, s2);