/* oobinline.c: *  * OOB inline receiver : */#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <errno.h>#include <string.h>#include <signal.h>#include <fcntl.h>#include <sys/ioctl.h>#include <sys/types.h>#include <sys/socket.h>extern void bail(char *on_what);extern int BindAccept(char *addr);/* * SIGURG signal handler : */static voidsigurg(int signo) {    write(1,"[SIGURG]\n",9);    signal(SIGURG,sigurg);}/* * Emulate the IEEE Std 1003.1g * standard function sockatmark(3): */static intSockatmark(int s) {    int z;    int flag;    z = ioctl(s,SIOCATMARK,&flag);    if ( z == -1 )        return -1;    return flag ? 1 : 0;}intmain(int argc,char **argv) {    int z;               /* Status */    int s;               /* Socket */    int oobinline=1; /* OOB inline */    char buf[256];    /*     * Use a server address from the command     * line, if one has been provided.     * Otherwise, this program will default     * to using the arbitrary address     * 127.0.0.1 :     */    s = BindAccept(argc >= 2        ? argv[1]        : "127.0.0.1:9011");    /*     * Establish ownership :     */    z = fcntl(s,F_SETOWN,getpid());    if ( z == -1 )        bail("fcntl(2)");    /*     * Catch SIGURG :     */    signal(SIGURG,sigurg);    /*     * Receive the OOB data inline:     */    z = setsockopt(s,        SOL_SOCKET,        SO_OOBINLINE,        &oobinline,        sizeof oobinline);    if ( z == -1 )        bail("setsockopt(2)");    for (;;) {        printf("\n[%s]\n",            Sockatmark(s)                ? "AT MARK"                : "No Mark");        z = recv(s,buf,sizeof buf,0);        if ( z == -1 )            bail("recv(2)");        if ( z == 0 )            break;        buf[z] = 0;        printf("rcv '%s' (%d)\n",            buf, z);    }    close(s);    return 0;}