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
68 struct sockaddr_in cli_add;
70 char debug[MAXLINE], ipaddr[20];
72 * Input section: decode parameters passed in the calling
76 opterr = 0; /* don't want writing to stderr */
77 while ( (i = getopt(argc, argv, "hkdicw:")) != -1) {
83 printf("Wrong -h option use\n");
100 waiting = strtol(optarg, NULL, 10);
102 case '?': /* unrecognized options */
103 printf("Unrecognized options -%c\n",optopt);
105 default: /* should not reached */
109 /* ***********************************************************
111 * Options processing completed
113 * Main code beginning
115 * ***********************************************************/
116 /* Main code begin here */
117 if (compat) { /* install signal handler */
118 Signal(SIGCHLD, HandSigCHLD); /* non restarting handler */
120 SignalRestart(SIGCHLD, HandSigCHLD); /* restarting handler */
122 /* create and bind socket */
123 if ( (list_fd = sockbind(argv[optind], "echo", 6, SOCK_STREAM)) < 0) {
126 /* release privileges and go daemon */
127 if (setgid(65534) !=0) { /* first give away group privileges */
128 perror("cannot give away group privileges");
131 if (setuid(65534) !=0) { /* and only after user ... */
132 perror("cannot give away user privileges");
135 if (demonize) { /* go daemon */
136 openlog(argv[0], 0, LOG_DAEMON); /* open logging */
137 if (daemon(0, 0) != 0) {
138 perror("cannot start as daemon");
143 if (listen(list_fd, BACKLOG) < 0 ) {
144 PrintErr("listen error");
147 if (waiting) sleep(waiting);
148 /* handle echo to client */
150 /* accept connection */
151 len = sizeof(cli_add);
152 while (((conn_fd = accept(list_fd, (struct sockaddr *)&cli_add, &len))
153 < 0) && (errno == EINTR));
155 PrintErr("accept error");
159 inet_ntop(AF_INET, &cli_add.sin_addr, ipaddr, sizeof(ipaddr));
160 snprintf(debug, MAXLINE, "Accepted connection form %s\n", ipaddr);
162 syslog(LOG_DEBUG, debug);
167 /* fork to handle connection */
168 if ( (pid = fork()) < 0 ){
169 PrintErr("fork error");
172 if (pid == 0) { /* child */
173 close(list_fd); /* close listening socket */
174 if (keepalive) { /* enable keepalive ? */
175 setsockopt(conn_fd, SOL_SOCKET, SO_KEEPALIVE,
176 &keepalive, sizeof(keepalive));
178 ServEcho(conn_fd); /* handle echo */
180 snprintf(debug, MAXLINE, "Closed connection %s\n", ipaddr);
182 syslog(LOG_DEBUG, debug);
188 } else { /* parent */
189 close(conn_fd); /* close connected socket */
192 /* normal exit, never reached */
196 * routine to print usage info and exit
199 printf("Elementary echo server\n");
201 printf(" echod [-h] \n");
202 printf(" -h print this help\n");
203 printf(" -d write debug info\n");
204 printf(" -k enable keepalive on connection\n");
205 printf(" -i use interactively\n");
206 printf(" -c disable BSD semantics\n");
207 printf(" -w N wait N sec. before calling accept\n");
211 * routine to handle echo for connection
213 void ServEcho(int sockfd) {
214 char buffer[MAXLINE];
216 char debug[MAXLINE+20];
217 /* main loop, reading 0 char means client close connection */
218 while ( (nread = read(sockfd, buffer, MAXLINE)) != 0) {
220 PrintErr("Errore in lettura");
223 nwrite = FullWrite(sockfd, buffer, nread);
225 PrintErr("Errore in scrittura");
230 snprintf(debug, MAXLINE+20, "Letti %d byte, %s", nread, buffer);
231 if (demonize) { /* daemon mode */
232 syslog(LOG_DEBUG, debug);
241 * routine to print error on stout or syslog
243 void PrintErr(char * error) {
244 if (demonize) { /* daemon mode */
245 syslog(LOG_ERR, "%s: %m", error); /* log string and error message */