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 1.8 2003/07/27 14:28:19 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 code */
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
64 struct sockaddr_in serv_add, cli_add;
66 char debug[MAXLINE], ipaddr[20];
68 * Input section: decode parameters passed in the calling
72 opterr = 0; /* don't want writing to stderr */
73 while ( (i = getopt(argc, argv, "hdiw:")) != -1) {
79 printf("Wrong -h option use\n");
90 waiting = strtol(optarg, NULL, 10);
92 case '?': /* unrecognized options */
93 printf("Unrecognized options -%c\n",optopt);
95 default: /* should not reached */
99 /* ***********************************************************
101 * Options processing completed
103 * Main code beginning
105 * ***********************************************************/
106 /* install SIGCHLD handler */
107 Signal(SIGCHLD, HandSigCHLD); /* establish handler */
109 if ( (list_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
110 perror("Socket creation error");
113 /* initialize address */
114 memset((void *)&serv_add, 0, sizeof(serv_add)); /* clear server address */
115 serv_add.sin_family = AF_INET; /* address type is INET */
116 serv_add.sin_port = htons(7); /* echo port is 7 */
117 serv_add.sin_addr.s_addr = htonl(INADDR_ANY); /* connect from anywhere */
119 if (bind(list_fd, (struct sockaddr *)&serv_add, sizeof(serv_add)) < 0) {
120 perror("bind error");
123 /* release privileges and go daemon */
124 if (setgid(65534) !=0) { /* first give away group privileges */
125 perror("cannot give away group privileges");
128 if (setuid(65534) !=0) { /* and only after user ... */
129 perror("cannot give away user privileges");
132 if (demonize) { /* go daemon */
133 openlog(argv[0], 0, LOG_DAEMON); /* open logging */
134 if (daemon(0, 0) != 0) {
135 perror("cannot start as daemon");
140 if (listen(list_fd, BACKLOG) < 0 ) {
141 PrintErr("listen error");
144 if (waiting) sleep(waiting);
145 /* handle echo to client */
147 /* accept connection */
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 } else { /* parent */
173 close(conn_fd); /* close connected socket */
176 /* normal exit, never reached */
180 * routine to print usage info and exit
183 printf("Elementary echo server\n");
185 printf(" echod [-h] \n");
186 printf(" -h print this help\n");
187 printf(" -d write debug info\n");
188 printf(" -i use interactively\n");
189 printf(" -w N wait N sec. before calling accept\n");
193 * routine to handle echo for connection
195 void ServEcho(int sockfd) {
196 char buffer[MAXLINE];
198 char debug[MAXLINE+20];
200 /* main loop, reading 0 char means client close connection */
201 while ( (nread = read(sockfd, buffer, MAXLINE)) != 0) {
203 snprintf(debug, MAXLINE+20, "Errore in lettura: %s \n",
205 if (demonize) { /* daemon mode */
206 syslog(LOG_DEBUG, debug);
211 nwrite = FullWrite(sockfd, buffer, nread);
213 snprintf(debug, MAXLINE+20, "Errore in scrittura: %s \n",
215 if (demonize) { /* daemon mode */
216 syslog(LOG_DEBUG, debug);
223 snprintf(debug, MAXLINE+20, "Letti %d byte, %s", nread, buffer);
224 if (demonize) { /* daemon mode */
225 syslog(LOG_DEBUG, debug);
234 * routine to print error on stout or syslog
236 void PrintErr(char * error) {
237 if (demonize) { /* daemon mode */
238 syslog(LOG_ERR, error);