| Normally, we should use getsockopt(fd, SOL_SOCKET, SO_ERROR) on a pending |
| connect() to detect whether the connection correctly established or not. |
| |
| Unfortunately, getsockopt() does not report the status of a pending connection, |
| which means that it returns 0 if the connection is still pending. This has to |
| be expected, because as the name implies it, it only returns errors. |
| |
| With the speculative I/O, a new problem was introduced : if we pretend the |
| socket was indicated as ready and we go to the socket's write() function, |
| a pending connection will then inevitably be identified as established. |
| |
| In fact, there are solutions to this issue : |
| |
| - send() returns -EAGAIN if it cannot write, so that as long as there are |
| pending data in the buffer, we'll be informed about the status of the |
| connection |
| |
| - connect() on an already pending connection will return -1 with errno set to |
| one of the following values : |
| - EALREADY : connection already in progress |
| - EISCONN : connection already established |
| - anything else will indicate an error. |
| |
| => So instead of using getsockopt() on a pending connection with no data, we |
| will switch to connect(). This implies that the connection address must be |
| known within the socket's write() function. |
| |
| |