LinuxQuestions.org - connect() timeout change

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- - connect() timeout change (https://www.linuxquestions.org/questions/programming-9/connect-timeout-change-145433/)

connect() timeout change

Can the connect() function have its timeout changed? on redhat its about 3 minutes and I want to change that to about 10 seconds.

the solution is using nonblocking i/o and select. here is the function i use:

Code:

//do a nonblocking connect 

//  return -1 on a system call error, 0 on success

//  sa - host to connect to, filled by caller

//  sock - the socket to connect

//  timeout - how long to wait to connect

inline int 

conn_nonb(struct sockaddr_in sa, int sock, int timeout)

{  

    int flags = 0, error = 0, ret = 0;

    fd_set  rset, wset;

    socklen_t  len = sizeof(error);

    struct timeval  ts;

    

    ts.tv_sec = timeout;

    

    //clear out descriptor sets for select

    //add socket to the descriptor sets

    FD_ZERO(&rset);

    FD_SET(sock, &rset);

    wset = rset;    //structure assignment ok

    

    //set socket nonblocking flag

    if( (flags = fcntl(sock, F_GETFL, 0)) < 0)

        return -1;

    

    if(fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0)

        return -1;

    

    //initiate non-blocking connect

    if( (ret = connect(sock, (struct sockaddr *)&sa, 16)) < 0 )

        if (errno != EINPROGRESS)

            return -1;



    if(ret == 0)    //then connect succeeded right away

        goto done;

    

    //we are waiting for connect to complete now

    if( (ret = select(sock + 1, &rset, &wset, NULL, (timeout) ? &ts : NULL)) < 0)

        return -1;

    if(ret == 0){  //we had a timeout

        errno = ETIMEDOUT;

        return -1;

    }



    //we had a positivite return so a descriptor is ready

    if (FD_ISSET(sock, &rset) || FD_ISSET(sock, &wset)){

        if(getsockopt(sock, SOL_SOCKET, SO_ERROR, &error, &len) < 0)

            return -1;

    }else

        return -1;



    if(error){  //check if we had a socket error

        errno = error;

        return -1;

    }



done:

    //put socket back in blocking mode

    if(fcntl(sock, F_SETFL, flags) < 0)

        return -1;



    return 0;

}

HTH

ill give that a try, Thanks.

im afraid that didnt work ,infamous41md. it compiled alright, but given a 10 second timeout it still waited < 1 second and didnt connect to a valid host im not sure whats wrong

well i use it everyday, so im pretty sure it works :D could i see how u used it? u say it returned right away? you should be checking the errror return for -1 and calling perror() if it is.

connect() will return an immediate failure if it is able to determine that it can't establish the connection. This is often the case when you are trying to connect to a socket on the same machine.

The function given above will wait _up to_ timeout seconds. In theory, you could change it to retry every now and then until your timeout value is exhausted.

well, I did try your code infamous41md , and it compiles OK, but when I use it, the timeout comes after 333 sec, while when I used usuall connect, timeout came after 189 sec....

Code:

 

    s_in.sin_family = PF_INET;

    s_in.sin_port = htons(21);

    sprintf(ip,"147.232.153.5");  //just for testing purposes, it's NOT my IP

    s_in.sin_addr.s_addr=inet_addr(ip);

    con = conn_nonb(s_in,s,10);

    if(con==-1)

    {

            printf("%d - IP = %s - Connection failed\n",getpid(),ip);

            perror();

    }

What am I doing wrong? Thx for help.
J.

oh, I forgot:

Code:

    int s;

    s = socket(PF_INET, SOCK_STREAM, 0);

    if(s<0)

    {

        perror("socket");

    }

I believe you can use setsockopt() with the SO_RCVTIMEO or SO_SNDTIMEO options. I'm not sure if those settings have any effect on connect(), but it should give you a place to look ;)

well, I want to do that under Linux...

add this:
ts.tv_usec = 0;

right below
ts.tv_sec = timeout

:D thx, now it works fine
J.