Linux, sockets, non-blocking connect

Question

I want to create a non-blocking connect. Like this:

socket.connect(); // returns immediately

For this, I use another thread, an infinite lo

Answer 1

There are a few ways to test if a nonblocking connect succeeds.

1. call getpeername() first, if it failed with error ENOTCONN, the connection failed. then call getsockopt with SO_ERROR to get the pending error on the socket
2. call read with a length of 0. if the read failed, the connection failed, and the errno for read indicates why the connection failed; read returns 0 if connection succeeds
3. call connect again; if the errno is EISCONN, the connection is already connected and the first connect succeeded.

Ref: UNIX Network Programming V1