HP Rp7410 BSD Sockets Interface Programmer's Guide - Page 106

Using Internet Datagram Sockets Example Using Datagram Sockets struct in_addr reqaddr; /* for returned internet address */ #define ADDRNOTFOUND 0xffffffff /* value returned for unknown host */ #define RETRIES 5 /* # of times to retry before giving up */ /* * H A N D L E R * * This routine is the signal handler for the alarm signal. * It simply re-installs itself as the handler and returns. */ handler() { signal(SIGALRM, handler); } /* * M A I N * * This routine is the client which requests service from * the remote "example server". It will send a message to the * remote nameserver requesting the internet address corresponding * to a given hostname. The server will look up the name, and * return its internet address. The returned address will be * written to stdout. * * The name of the system to which the requests will be sent is * given as the first parameter to the command. The second * parameter should be the name of the target host for which the * internet address is sought. */ main(argc, argv) int argc; char *argv[]; { int i; int retry = RETRIES; /* holds the retry count */ char *inet_ntoa(); if (argc != 3) { fprintf(stderr, "Usage: argv[0]); exit(1); } %s \n", /* clear out address structures */ memset ((char *)&myaddr_in, 0, sizeof(struct sockaddr_in)); memset ((char *)&servaddr_in, 0, sizeof(struct sockaddr_in)); /* Set up the server address. */ servaddr_in.sin_family = AF_INET; /* Get the host info for the server's hostname that the * user passed in. */ hp = gethostbyname (argv[1]); if (hp == NULL) { fprintf(stderr, "%s: %s not found in /etc/hosts\n", argv[0], argv[1]); 106 Chapter 4