Getting Invalid argument as a failure reason while enabling TCP keep alive option?

Question

I have tried to implement TCP client to send TCP keep alive request but all the option were failed with invalid argument. My code looks like as below:

    #define SERVER_ADDRESS "94.23.3.169" /* Server address */
    #define PORT 1010/* the port client will be connecting to */
    
    
    static int16_t i16Sockfd;
    
    void vEnablekeepalive(int16_t i16Sockfd;)
    {
        int16_t i16Enable;
        socklen_t optlen = sizeof(i16Enable);
    
        /* Check the status for the keepalive option */
        if(getsockopt(i16Sockfd, SOL_SOCKET, SO_KEEPALIVE, &i16Enable, &optlen) < 0) {
            perror("getsockopt");
        }
        MSG("Before KEEP_ALIVE OPTION:%d\n",i16Enable);
    
        i16Enable = 1;
        if(setsockopt(i16Sockfd, SOL_SOCKET, SO_KEEPALIVE, &i16Enable, sizeof(i16Enable)) == -1){
            perror("setsockopt");
        }
    
        /* Check the status for the keepalive option */
        if(getsockopt(i16Sockfd, SOL_SOCKET, SO_KEEPALIVE, &i16Enable, &optlen) < 0) {
            perror("getsockopt);
        }
        MSG("After KEEP_ALIVE OPTION:%d\n",i16Enable);
    
        int16_t i16Idle = 600;
        if(setsockopt(i16Sockfd, IPPROTO_TCP, TCP_KEEPIDLE, &i16Idle, sizeof(i16Idle)) == -1){
            perror("Idle");
        }
    
        int16_t i16Interval = 60;
        if(setsockopt(i16Sockfd, IPPROTO_TCP, TCP_KEEPINTVL, &i16Interval, sizeof(i16Interval)) == -1){
            perror("Interval");
        }
    
        int16_t i16Maxcount = 5;
        if(setsockopt(i16Sockfd, IPPROTO_TCP, TCP_KEEPCNT, &i16Maxcount, sizeof(i16Maxcount)) == -1){
            perror("Maxcount");
        }
    }
    
    int main()
    {
        struct sockaddr_in their_addr;
        
        if ((i16Sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1) {
            perror("socket");
        }
              
        Enablekeepalive(i16Sockfd);
    
        their_addr.sin_family = AF_INET; /* host byte order */
        their_addr.sin_port = htons(PORT); /* short, network byte order */
        their_addr.sin_addr.s_addr = inet_addr(SERVER_ADDRESS);
        zero(&(their_addr.sin_zero), 8); /* zero the rest of the struct */
        if (connect(i16Sockfd, (struct sockaddr*) &their_addr,sizeof(struct sockaddr)) == -1) {
            perror("connect");
            close(i16Sockfd);
        }
              
    }

I can't get why it is giving invalid argument for all setsockopt API. Is there anything wrong to set keep alive option using setsockopt?

Why are you using `int16_t` for all the places that require an `int`? They are likely not the same size on your system. — kaylum, Sep 30 '20 at 04:41

score 0 · Answer 1 · answered Sep 30 '20 at 04:58

0

SO_KEEPALIVE is for a connection oriented socket. So please connect your socket first and set SO_KEEPALIVE after that.

answered Sep 30 '20 at 04:58

Steffen Ullrich

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I have one more query: If i have enable keep alive and set all option for keep alive using above code then do i need to change below setting? **# echo 600 > /proc/sys/net/ipv4/tcp_keepalive_time # echo 60 > /proc/sys/net/ipv4/tcp_keepalive_intvl # echo 20 > /proc/sys/net/ipv4/tcp_keepalive_probes** – Abhishek Lakhara Oct 01 '20 at 07:01
@AbhishekLakhara: You don't need to change the settings if you can live with the current settings. Note that you can also apply socket specific settings for the keep alive timings - see https://tldp.org/HOWTO/html_single/TCP-Keepalive-HOWTO/#setsockopt – Steffen Ullrich Oct 01 '20 at 15:15

Shawn · Answer 2 · 2020-09-30T05:14:23.903

From the socket(7) documentation, which covers SO_XXX socket options:

The socket options listed below can be set by using setsockopt(2) and read with getsockopt(2) with the socket level set to SOL_SOCKET for all sockets. Unless otherwise noted, optval is a pointer to an int.

and

SO_KEEPALIVE Enable sending of keep-alive messages on connection-oriented sockets. Expects an integer boolean flag.

The Linux-specific TCP_KEEPIDLE etc. options also expect an int argument.

An int16_t like you're using as the option type is unlikely to be the same size as an int on typical systems these days, hence the errors. Use int instead.

Getting Invalid argument as a failure reason while enabling TCP keep alive option?

2 Answers2