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)
23 * Third version, use sockbind
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 */
119 /* create and bind socket */
120 if ( (list_fd = sockbind(argv[optind], "echo", 6, SOCK_STREAM)) < 0) {
121 if (errno) perror("Socket creation error");
124 /* release privileges and go daemon */
125 if (setgid(65534) !=0) { /* first give away group privileges */
126 perror("cannot give away group privileges");
129 if (setuid(65534) !=0) { /* and only after user ... */
130 perror("cannot give away user privileges");
133 if (demonize) { /* go daemon */
134 openlog(argv[0], 0, LOG_DAEMON); /* open logging */
135 if (daemon(0, 0) != 0) {
136 perror("cannot start as daemon");
141 if (listen(list_fd, BACKLOG) < 0 ) {
142 PrintErr("listen error");
145 if (waiting) sleep(waiting);
146 /* handle echo to client */
148 /* accept connection */
149 len = sizeof(cli_add);
150 while (((conn_fd = accept(list_fd, (struct sockaddr *)&cli_add, &len))
151 < 0) && (errno == EINTR));
153 PrintErr("accept error");
157 inet_ntop(AF_INET, &cli_add.sin_addr, ipaddr, sizeof(ipaddr));
158 snprintf(debug, MAXLINE, "Accepted connection form %s\n", ipaddr);
160 syslog(LOG_DEBUG, debug);
165 /* fork to handle connection */
166 if ( (pid = fork()) < 0 ){
167 PrintErr("fork error");
170 if (pid == 0) { /* child */
171 close(list_fd); /* close listening socket */
172 ServEcho(conn_fd); /* handle echo */
174 snprintf(debug, MAXLINE, "Closed connection %s\n", ipaddr);
176 syslog(LOG_DEBUG, debug);
182 } else { /* parent */
183 close(conn_fd); /* close connected socket */
186 /* normal exit, never reached */
190 * routine to print usage info and exit
193 printf("Elementary echo server\n");
195 printf(" echod [-h] \n");
196 printf(" -h print this help\n");
197 printf(" -d write debug info\n");
198 printf(" -i use interactively\n");
199 printf(" -c disable BSD semantics\n");
200 printf(" -w N wait N sec. before calling accept\n");
204 * routine to handle echo for connection
206 void ServEcho(int sockfd) {
207 char buffer[MAXLINE];
209 char debug[MAXLINE+20];
210 /* main loop, reading 0 char means client close connection */
211 while ( (nread = read(sockfd, buffer, MAXLINE)) != 0) {
213 PrintErr("Errore in lettura");
216 nwrite = FullWrite(sockfd, buffer, nread);
218 PrintErr("Errore in scrittura");
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, "%s: %m", error); /* log string and error message */