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
31 ****************************************************************/
33 * Include needed headers
35 #include <sys/types.h> /* predefined types */
36 #include <unistd.h> /* include unix standard library */
37 #include <arpa/inet.h> /* IP addresses conversion utiliites */
38 #include <sys/socket.h> /* socket library */
39 #include <stdio.h> /* include standard I/O library */
41 #include <syslog.h> /* syslog system functions */
42 #include <signal.h> /* signal functions */
43 #include <errno.h> /* error code */
44 #include <string.h> /* error strings */
51 int demonize = 1; /* daemon use option: default is daemon */
52 int debugging = 0; /* debug info printing option: default is no debug */
53 /* Subroutines declaration */
55 void ServEcho(int sockfd);
56 void PrintErr(char * error);
57 /* Program beginning */
58 int main(int argc, char *argv[])
61 * 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, "hdicw:")) != -1) {
82 printf("Wrong -h option use\n");
96 waiting = strtol(optarg, NULL, 10);
98 case '?': /* unrecognized options */
99 printf("Unrecognized options -%c\n",optopt);
101 default: /* should not reached */
105 /* ***********************************************************
107 * Options processing completed
109 * Main code beginning
111 * ***********************************************************/
112 /* Main code begin here */
113 if (compat) { /* install signal handler */
114 Signal(SIGCHLD, HandSigCHLD); /* non restarting handler */
116 SignalRestart(SIGCHLD, HandSigCHLD); /* restarting handler */
118 /* create and bind socket */
119 if ( (list_fd = sockbind(argv[optind], "echo", 6, SOCK_STREAM)) < 0) {
122 /* release privileges and go daemon */
123 if (setgid(65534) !=0) { /* first give away group privileges */
124 perror("cannot give away group privileges");
127 if (setuid(65534) !=0) { /* and only after user ... */
128 perror("cannot give away user privileges");
131 if (demonize) { /* go daemon */
132 openlog(argv[0], 0, LOG_DAEMON); /* open logging */
133 if (daemon(0, 0) != 0) {
134 perror("cannot start as daemon");
139 if (listen(list_fd, BACKLOG) < 0 ) {
140 PrintErr("listen error");
143 if (waiting) sleep(waiting);
144 /* handle echo to client */
146 /* accept connection */
147 len = sizeof(cli_add);
148 while (((conn_fd = accept(list_fd, (struct sockaddr *)&cli_add, &len))
149 < 0) && (errno == EINTR));
151 PrintErr("accept error");
155 inet_ntop(AF_INET, &cli_add.sin_addr, ipaddr, sizeof(ipaddr));
156 snprintf(debug, MAXLINE, "Accepted connection form %s\n", ipaddr);
158 syslog(LOG_DEBUG, debug);
163 /* fork to handle connection */
164 if ( (pid = fork()) < 0 ){
165 PrintErr("fork error");
168 if (pid == 0) { /* child */
169 close(list_fd); /* close listening socket */
170 ServEcho(conn_fd); /* handle echo */
172 snprintf(debug, MAXLINE, "Closed connection %s\n", ipaddr);
174 syslog(LOG_DEBUG, debug);
180 } else { /* parent */
181 close(conn_fd); /* close connected socket */
184 /* normal exit, never reached */
188 * routine to print usage info and exit
191 printf("Elementary echo server\n");
193 printf(" echod [-h] \n");
194 printf(" -h print this help\n");
195 printf(" -d write debug info\n");
196 printf(" -i use interactively\n");
197 printf(" -c disable BSD semantics\n");
198 printf(" -w N wait N sec. before calling accept\n");
202 * routine to handle echo for connection
204 void ServEcho(int sockfd) {
205 char buffer[MAXLINE];
207 char debug[MAXLINE+20];
208 /* main loop, reading 0 char means client close connection */
209 while ( (nread = read(sockfd, buffer, MAXLINE)) != 0) {
211 PrintErr("Errore in lettura");
214 nwrite = FullWrite(sockfd, buffer, nread);
216 PrintErr("Errore in scrittura");
221 snprintf(debug, MAXLINE+20, "Letti %d byte, %s", nread, buffer);
222 if (demonize) { /* daemon mode */
223 syslog(LOG_DEBUG, debug);
232 * routine to print error on stout or syslog
234 void PrintErr(char * error) {
235 if (demonize) { /* daemon mode */
236 syslog(LOG_ERR, "%s: %m", error); /* log string and error message */