3 * Copyright (C) 2001-2003 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 * $Id: TCP_echod.c,v 1.12 2003/08/03 18:12:47 piccardi Exp $
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 */
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
65 struct sockaddr_in serv_add, cli_add;
67 char debug[MAXLINE], ipaddr[20];
69 * Input section: decode parameters passed in the calling
73 opterr = 0; /* don't want writing to stderr */
74 while ( (i = getopt(argc, argv, "hdicw:")) != -1) {
80 printf("Wrong -h option use\n");
94 waiting = strtol(optarg, NULL, 10);
96 case '?': /* unrecognized options */
97 printf("Unrecognized options -%c\n",optopt);
99 default: /* should not reached */
103 /* ***********************************************************
105 * Options processing completed
107 * Main code beginning
109 * ***********************************************************/
110 /* Main code begin here */
111 if (compat) { /* install signal handler */
112 Signal(SIGCHLD, HandSigCHLD); /* non restarting handler */
114 SignalRestart(SIGCHLD, HandSigCHLD); /* restarting handler */
117 if ( (list_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
118 perror("Socket creation error");
121 /* initialize address */
122 memset((void *)&serv_add, 0, sizeof(serv_add)); /* clear server address */
123 serv_add.sin_family = AF_INET; /* address type is INET */
124 serv_add.sin_port = htons(7); /* echo port is 7 */
125 serv_add.sin_addr.s_addr = htonl(INADDR_ANY); /* connect from anywhere */
127 if (bind(list_fd, (struct sockaddr *)&serv_add, sizeof(serv_add)) < 0) {
128 perror("bind error");
131 /* release privileges and go daemon */
132 if (setgid(65534) !=0) { /* first give away group privileges */
133 perror("cannot give away group privileges");
136 if (setuid(65534) !=0) { /* and only after user ... */
137 perror("cannot give away user privileges");
140 if (demonize) { /* go daemon */
141 openlog(argv[0], 0, LOG_DAEMON); /* open logging */
142 if (daemon(0, 0) != 0) {
143 perror("cannot start as daemon");
148 if (listen(list_fd, BACKLOG) < 0 ) {
149 PrintErr("listen error");
152 if (waiting) sleep(waiting);
153 /* handle echo to client */
155 /* accept connection */
156 while (((conn_fd = accept(list_fd, (struct sockaddr *)&cli_add, &len))
157 < 0) && (errno == EINTR));
159 PrintErr("accept error");
163 inet_ntop(AF_INET, &cli_add.sin_addr, ipaddr, sizeof(ipaddr));
164 snprintf(debug, MAXLINE, "Accepted connection form %s\n", ipaddr);
166 syslog(LOG_DEBUG, debug);
171 /* fork to handle connection */
172 if ( (pid = fork()) < 0 ){
173 PrintErr("fork error");
176 if (pid == 0) { /* child */
177 close(list_fd); /* close listening socket */
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(" -i use interactively\n");
205 printf(" -c disable BSD semantics\n");
206 printf(" -w N wait N sec. before calling accept\n");
210 * routine to handle echo for connection
212 void ServEcho(int sockfd) {
213 char buffer[MAXLINE];
215 char debug[MAXLINE+20];
216 /* main loop, reading 0 char means client close connection */
217 while ( (nread = read(sockfd, buffer, MAXLINE)) != 0) {
219 PrintErr("Errore in lettura");
222 nwrite = FullWrite(sockfd, buffer, nread);
224 PrintErr("Errore in scrittura");
229 snprintf(debug, MAXLINE+20, "Letti %d byte, %s", nread, buffer);
230 if (demonize) { /* daemon mode */
231 syslog(LOG_DEBUG, debug);
240 * routine to print error on stout or syslog
242 void PrintErr(char * error) {
243 if (demonize) { /* daemon mode */
244 syslog(LOG_ERR, "%s: %m", error); /* log string and error message */