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)
25 * Author: Simone Piccardi
28 * Usage: echod -h give all info
32 ****************************************************************/
34 * Include needed headers
36 #include <sys/types.h> /* predefined types */
37 #include <unistd.h> /* include unix standard library */
38 #include <arpa/inet.h> /* IP addresses conversion utiliites */
39 #include <sys/socket.h> /* socket library */
40 #include <stdio.h> /* include standard I/O library */
42 #include <syslog.h> /* syslog system functions */
43 #include <signal.h> /* signal functions */
44 #include <errno.h> /* error code */
45 #include <string.h> /* error strings */
52 int demonize = 1; /* daemon use option: default is daemon */
53 int debugging = 0; /* debug info printing option: default is no debug */
54 /* Subroutines declaration */
56 void ServEcho(int sockfd);
57 void PrintErr(char * error);
58 /* Program beginning */
59 int main(int argc, char *argv[])
62 * Variables definition
68 struct sockaddr_in serv_add, 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, "hdicw:")) != -1) {
83 printf("Wrong -h option use\n");
97 waiting = strtol(optarg, NULL, 10);
99 case '?': /* unrecognized options */
100 printf("Unrecognized options -%c\n",optopt);
102 default: /* should not reached */
106 /* ***********************************************************
108 * Options processing completed
110 * Main code beginning
112 * ***********************************************************/
113 /* Main code begin here */
114 if (compat) { /* install signal handler */
115 Signal(SIGCHLD, HandSigCHLD); /* non restarting handler */
117 SignalRestart(SIGCHLD, HandSigCHLD); /* restarting handler */
120 if ( (list_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
121 perror("Socket creation error");
124 /* initialize address */
125 memset((void *)&serv_add, 0, sizeof(serv_add)); /* clear server address */
126 serv_add.sin_family = AF_INET; /* address type is INET */
127 serv_add.sin_port = htons(7); /* echo port is 7 */
128 serv_add.sin_addr.s_addr = htonl(INADDR_ANY); /* connect from anywhere */
130 if (bind(list_fd, (struct sockaddr *)&serv_add, sizeof(serv_add)) < 0) {
131 perror("bind error");
134 /* release privileges and go daemon */
135 if (setgid(65534) !=0) { /* first give away group privileges */
136 perror("cannot give away group privileges");
139 if (setuid(65534) !=0) { /* and only after user ... */
140 perror("cannot give away user privileges");
143 if (demonize) { /* go daemon */
144 openlog(argv[0], 0, LOG_DAEMON); /* open logging */
145 if (daemon(0, 0) != 0) {
146 perror("cannot start as daemon");
151 if (listen(list_fd, BACKLOG) < 0 ) {
152 PrintErr("listen error");
155 if (waiting) sleep(waiting);
156 /* handle echo to client */
158 /* accept connection */
159 len = sizeof(cli_add);
160 while (((conn_fd = accept(list_fd, (struct sockaddr *)&cli_add, &len))
161 < 0) && (errno == EINTR));
163 PrintErr("accept error");
167 inet_ntop(AF_INET, &cli_add.sin_addr, ipaddr, sizeof(ipaddr));
168 snprintf(debug, MAXLINE, "Accepted connection form %s\n", ipaddr);
170 syslog(LOG_DEBUG, debug);
175 /* fork to handle connection */
176 if ( (pid = fork()) < 0 ){
177 PrintErr("fork error");
180 if (pid == 0) { /* child */
181 close(list_fd); /* close listening socket */
182 ServEcho(conn_fd); /* handle echo */
184 snprintf(debug, MAXLINE, "Closed connection %s\n", ipaddr);
186 syslog(LOG_DEBUG, debug);
192 } else { /* parent */
193 close(conn_fd); /* close connected socket */
196 /* normal exit, never reached */
200 * routine to print usage info and exit
203 printf("Elementary echo server\n");
205 printf(" echod [-h] \n");
206 printf(" -h print this help\n");
207 printf(" -d write debug info\n");
208 printf(" -i use interactively\n");
209 printf(" -c disable BSD semantics\n");
210 printf(" -w N wait N sec. before calling accept\n");
214 * routine to handle echo for connection
216 void ServEcho(int sockfd) {
217 char buffer[MAXLINE];
219 char debug[MAXLINE+20];
220 /* main loop, reading 0 char means client close connection */
221 while ( (nread = read(sockfd, buffer, MAXLINE)) != 0) {
223 PrintErr("Errore in lettura");
226 nwrite = FullWrite(sockfd, buffer, nread);
228 PrintErr("Errore in scrittura");
233 snprintf(debug, MAXLINE+20, "Letti %d byte, %s", nread, buffer);
234 if (demonize) { /* daemon mode */
235 syslog(LOG_DEBUG, debug);
244 * routine to print error on stout or syslog
246 void PrintErr(char * error) {
247 if (demonize) { /* daemon mode */
248 syslog(LOG_ERR, "%s: %m", error); /* log string and error message */