3 * Copyright (C) 2004 Simone Piccardi
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or (at
8 * your option) any later version.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 /****************************************************************
22 * Elementary UDP client for daytime service (port 13)
24 * Author: Simone Piccardi
27 * Usage: daytime -h give all info's
29 ****************************************************************/
31 * Include needed headers
33 #include <sys/types.h> /* primitive system data types */
34 #include <unistd.h> /* unix standard library */
35 #include <arpa/inet.h> /* IP addresses conversion utilities */
36 #include <sys/socket.h> /* socket constants, types and functions */
37 #include <stdio.h> /* standard I/O library */
38 #include <stdlib.h> /* standard library */
43 int main(int argc, char *argv[])
46 * Variables definition
50 struct sockaddr_in addr;
53 * Input section: decode parameters passed in the calling
56 opterr = 0; /* don't want writing to stderr */
57 while ( (i = getopt(argc, argv, "h")) != -1) {
63 printf("Wrong -h option use\n");
67 case '?': /* unrecognized options */
68 printf("Unrecognized options -%c\n",optopt);
70 default: /* should not reached */
74 /* ***********************************************************
76 * Options processing completed
80 * ***********************************************************/
82 if ( (sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
83 perror("Socket creation error");
86 /* initialize address */
87 memset((void *) &addr, 0, sizeof(addr)); /* clear server address */
88 addr.sin_family = AF_INET; /* address type is INET */
89 addr.sin_port = htons(13); /* daytime port is 13 */
90 /* build address using inet_pton */
91 if ( (inet_pton(AF_INET, argv[optind], &addr.sin_addr)) <= 0) {
92 perror("Address creation error");
95 /* send request packet */
96 nread = sendto(sock, NULL, 0, 0, (struct sockaddr *)&addr, sizeof(addr));
98 perror("Request error");
101 nread = recvfrom(sock, buffer, MAXLINE, 0, NULL, NULL);
103 perror("Read error");
109 if (fputs(buffer, stdout) == EOF) { /* write daytime */
110 perror("fputs error");
118 * routine to print usage info and exit
121 printf("Take daytime from a remote host \n");
123 printf(" daytime [-h] [-v] [host in dotted decimal form] \n");
124 // printf(" -v set verbosity on\n");
125 printf(" -h print this help\n");