using AF_X25 and SOCK_SEQPACKET sample c code

/* af_x25.c:
 *
 * X.25 & SOCK_SEQPACKET Socket Address Example C Code:
 *
 */
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <errno.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <linux/x25.h>


/*
 * This function reports the error and
 * exits back to the shell:
 */
 static void displayError(const char *on_what) {
    perror(on_what);
    exit(1);
 }


 int main(int argc, char **argv, char **envp) {
    int z; /* Status return code */
    int sck_x25; /* Socket */
    struct sockaddr_x25 adr_x25;/* AF_X25 */
    int len_x25; /* length */
    const char x25_host[] /* X.121 addr */
    = "79400900";


 /* 
  * Create an AF_X25 socket 
  */
    sck_x25 = socket(AF_X25, SOCK_SEQPACKET, 0);


    if ( sck_x25 == -1 ) {
       displayError("socket()");
    }


 /* 
  * Form an AF_X25 Address 
  */
    adr_x25.sx25_family = AF_X25;
    strcpy(adr_x25.sx25_addr.x25_addr,x25_host);
    len_x25 = sizeof adr_x25;


 /* 
  * Bind the address to the socket 
  */
    z = bind(sck_x25, (struct sockaddr *)&adr_x25, len_x25);


    if ( z == -1 ) {
       displayError("bind()");
    }


    puts("X.25 SOCKETS :");
    system("cat /proc/net/x25");

    return 0;
 }
//output: 

$ ./af_x25

X.25 SOCKETS :

dest_addr src_addr dev lci st vs vr va t t2 t21 t22 t23 Snd-Q Rcv-Q inode

* 79400900    ???  000  0   0  0  0  0 3 200 180 180 0 0 104172

$

NOTE

Normally socket addresses with variable elements like the AF_UNIX address family require a computed length of the address. The Linux implementation of the AF_X25 socket address, however, simply requires the fixed length of sizeof (sockaddr_x25). The host number must be null terminated within the sockaddr_x25 structure.