setsocketopt.c

//Set any socket option in C for tcp sockets


   /* setsndrcv

    *

    * Set SO_SNDBUF & SO_RCVBUF Options:

   */

  #include <stdio.h>

  #include <unistd.h>

   #include <stdlib.h>

   #include <errno.h>

   #include <string.h>

  #include <sys/types.h>

  #include <sys/socket.h>

  #include <assert.h>



  /*

  * This function reports the error and

   * exits back to the shell: <$nopage>

					

   */

  static void

 bail(const char *on_what) {

     if ( errno != 0 ) {

         fputs(strerror(errno),stderr);

         fputs(": ",stderr);

     }

     fputs(on_what,stderr);

     fputc('\n',stderr);

    exit(1);

  }



  int

 main(int argc,char **argv) {

      int z;

      int s = -1;                /* Socket */

   int sndbuf=0;   /* Send buffer size */

   int rcvbuf=0;/* Receive buffer size */

     socklen_t optlen;  /* Option length */

     /*

      * Create a TCP/IP socket to use:

       */

    s = socket(PF_INET,SOCK_STREAM,0);

     if ( s == -1 )

         bail("socket(2)");

    /*

     * Set the SO_SNDBUF Size:

     */

     sndbuf = 5000;  /* Send buffer size */

     z = setsockopt(s,SOL_SOCKET,SO_SNDBUF,

         &sndbuf,sizeof sndbuf);

     if ( z )

         bail("setsockopt(s,SOL_SOCKET,"

             "SO_SNDBUF)");



     /*

      * Set the SO_RCVBUF Size: <$nopage>

				 <$nopage>

				 <$nopage>

      */

     rcvbuf = 8192;  /* Send buffer size */

     z = setsockopt(s,SOL_SOCKET,SO_RCVBUF,

         &rcvbuf,sizeof rcvbuf);

     if ( z )

         bail("setsockopt(s,SOL_SOCKET,"

             "SO_RCVBUF)");



     /*

      * As a check on the above…

      * Get socket option SO_SNDBUF:

      */

     optlen = sizeof sndbuf;

     z = getsockopt(s,SOL_SOCKET,SO_SNDBUF,

         &sndbuf,&optlen);

     if ( z )

         bail("getsockopt(s,SOL_SOCKET,"

             "SO_SNDBUF)");



     assert(optlen == sizeof sndbuf);



     /*

      * Get socket option SO_SNDBUF:

      */

     optlen = sizeof rcvbuf;

     z = getsockopt(s,SOL_SOCKET,SO_RCVBUF,

         &rcvbuf,&optlen);

     if ( z )

         bail("getsockopt(s,SOL_SOCKET,"

             "SO_RCVBUF)");



     assert(optlen == sizeof rcvbuf);



     /*

      * Report the buffer sizes: <$nopage>

				 <$nopage>

      */

     printf("Socket s : %d\n",s);

     printf(" Send buf: %d bytes\n",

         sndbuf);

     printf(" Recv buf: %d bytes\n",

         rcvbuf);



     close(s);

     return 0;

 }