socket timeout and remove O_NONBLOCK option

I implemented a socket timeout and retry but in order to do it I had to set the socket as a non-blocking socket. However, I need the socket to block. This was my attempt at a solution to these two problems. This is not working. Subsequent send calls block but never send any data. When I connect without the select and the timeout, subsequent send calls work normally.

References:

• C: socket connection timeout
• How to reset a socket back to blocking mode (after I set it to nonblocking mode)?

Code:

fd_set fdset;
struct timeval tv;
fcntl(dsock, F_SETFL, O_NONBLOCK);
tv.tv_sec = theDeviceTimeout;
tv.tv_usec = 0;
int retries=0;
logi(theLogOutput, LOG_INFO, "connecting to device socket num retrys: %i", theDeviceRetry);
for(retries=0;retries<theDeviceRetry;retries++) {
    connect(dsock, (struct sockaddr *)&daddr, sizeof daddr);


    FD_ZERO(&fdset);
    FD_SET(dsock, &fdset);
    if (select(dsock + 1, NULL, &fdset, NULL, &tv) == 1) {
        int so_error;
        socklen_t slen = sizeof so_error;
        getsockopt(dsock, SOL_SOCKET, SO_ERROR, &so_error, &slen);
        if (so_error == 0) {
            logi(theLogOutput, LOG_INFO, "connected to socket on port %i on %s", theDevicePort, theDeviceIP);
            break;
        } else {
            logi(theLogOutput, LOG_WARN, "connect to %i failed on ip %s because %s retries %i", theDevicePort, theDeviceIP, strerror(errno), retries);
            logi(theLogOutput, LOG_WARN, "failed to connect to device %s", strerror(errno));
            logi(theLogOutput, LOG_WARN, "error: %i %s", so_error, strerror(so_error));
            continue;
        }
    }
}

int opts;
opts = fcntl(dsock,F_GETFL);
logi(theLogOutput, LOG_DEBUG, "clearing nonblock option %i retries %i", opts, retries);
opts ^= O_NONBLOCK;
fcntl(dsock, F_SETFL, opts)开发者_StackOverflow中文版;

After you get the writeable event and no error you then need to call connect() again, as documented. This tells you whether the connection succeeded or failed.

Why not use SO_RCVTIMEO or SO_SNDTIMEO socket options? Or did I miss something in your question?