3 * Copyright (C) 2001-2004 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 TCP server for echo service (port 7)
24 * Author: Simone Piccardi
27 * Usage: echod -h give all info
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 <time.h> /* date and time constants, types and functions */
39 #include <syslog.h> /* syslog system functions */
40 #include <signal.h> /* signal constants, types and functions */
41 #include <errno.h> /* error definitions and routines */
42 #include <string.h> /* C strings library */
43 #include <stdlib.h> /* C standard library */
49 int demonize = 1; /* daemon use option: default is daemon */
50 int debugging = 0; /* debug info printing option: default is no debug */
51 /* Subroutines declaration */
53 void ServEcho(int sockfd);
54 void PrintErr(char * error);
55 /* Program beginning */
56 int main(int argc, char *argv[])
59 * Variables definition
67 struct sockaddr_in cli_add;
69 char debug[MAXLINE], ipaddr[20];
71 * Input section: decode parameters passed in the calling
75 opterr = 0; /* don't want writing to stderr */
76 while ( (i = getopt(argc, argv, "hkrdicw:")) != -1) {
82 printf("Wrong -h option use\n");
102 waiting = strtol(optarg, NULL, 10);
104 case '?': /* unrecognized options */
105 printf("Unrecognized options -%c\n",optopt);
107 default: /* should not reached */
111 /* ***********************************************************
113 * Options processing completed
115 * Main code beginning
117 * ***********************************************************/
118 /* Main code begin here */
119 if (compat) { /* install signal handler */
120 Signal(SIGCHLD, HandSigCHLD); /* non restarting handler */
122 SignalRestart(SIGCHLD, HandSigCHLD); /* restarting handler */
124 /* create and bind socket */
125 if ( (list_fd = sockbindopt(argv[optind], "echo", 6,
126 SOCK_STREAM, reuse)) < 0) {
129 /* release privileges and go daemon */
130 if (setgid(65534) !=0) { /* first give away group privileges */
131 perror("cannot give away group privileges");
134 if (setuid(65534) !=0) { /* and only after user ... */
135 perror("cannot give away user privileges");
138 if (demonize) { /* go daemon */
139 openlog(argv[0], 0, LOG_DAEMON); /* open logging */
140 if (daemon(0, 0) != 0) {
141 perror("cannot start as daemon");
146 if (listen(list_fd, BACKLOG) < 0 ) {
147 PrintErr("listen error");
150 if (waiting) sleep(waiting);
151 /* handle echo to client */
153 /* accept connection */
154 len = sizeof(cli_add);
155 while (((conn_fd = accept(list_fd, (struct sockaddr *)&cli_add, &len))
156 < 0) && (errno == EINTR));
158 PrintErr("accept error");
162 inet_ntop(AF_INET, &cli_add.sin_addr, ipaddr, sizeof(ipaddr));
163 snprintf(debug, MAXLINE, "Accepted connection form %s\n", ipaddr);
165 syslog(LOG_DEBUG, debug);
170 /* fork to handle connection */
171 if ( (pid = fork()) < 0 ){
172 PrintErr("fork error");
175 if (pid == 0) { /* child */
176 close(list_fd); /* close listening socket */
177 if (keepalive) { /* enable keepalive ? */
178 setsockopt(conn_fd, SOL_SOCKET, SO_KEEPALIVE,
179 &keepalive, sizeof(keepalive));
181 ServEcho(conn_fd); /* handle echo */
183 snprintf(debug, MAXLINE, "Closed connection %s\n", ipaddr);
185 syslog(LOG_DEBUG, debug);
191 } else { /* parent */
192 close(conn_fd); /* close connected socket */
195 /* normal exit, never reached */
199 * routine to print usage info and exit
202 printf("Elementary echo server\n");
204 printf(" echod [-h] \n");
205 printf(" -h print this help\n");
206 printf(" -d write debug info\n");
207 printf(" -k enable SO_KEEPALIVE\n");
208 printf(" -r enable SO_REUSEADDR\n");
209 printf(" -i use interactively\n");
210 printf(" -c disable BSD semantics\n");
211 printf(" -w N wait N sec. before calling accept\n");
215 * routine to handle echo for connection
217 void ServEcho(int sockfd) {
218 char buffer[MAXLINE];
220 char debug[MAXLINE+20];
221 /* main loop, reading 0 char means client close connection */
222 while ( (nread = read(sockfd, buffer, MAXLINE)) != 0) {
224 PrintErr("Errore in lettura");
227 nwrite = FullWrite(sockfd, buffer, nread);
229 PrintErr("Errore in scrittura");
234 snprintf(debug, MAXLINE+20, "Letti %d byte, %s", nread, buffer);
235 if (demonize) { /* daemon mode */
236 syslog(LOG_DEBUG, debug);
245 * routine to print error on stout or syslog
247 void PrintErr(char * error) {
248 if (demonize) { /* daemon mode */
249 syslog(LOG_ERR, "%s: %m", error); /* log string and error message */