+/* TCP_echod.c
+ *
+ * Copyright (C) 2001-2003 Simone Piccardi
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+/****************************************************************
+ *
+ * Program echod
+ * Elementary TCP server for echo service (port 7)
+ *
+ * Author: Simone Piccardi
+ * Jun. 2001
+ *
+ * Usage: echod -h give all info
+ *
+ * $Id: TCP_echod_second.c,v 1.1 2003/08/03 18:12:47 piccardi Exp $
+ *
+ ****************************************************************/
+/*
+ * Include needed headers
+ */
+#include <sys/types.h> /* predefined types */
+#include <unistd.h> /* include unix standard library */
+#include <arpa/inet.h> /* IP addresses conversion utiliites */
+#include <sys/socket.h> /* socket library */
+#include <stdio.h> /* include standard I/O library */
+#include <time.h>
+#include <syslog.h> /* syslog system functions */
+#include <signal.h> /* signal functions */
+#include <errno.h> /* error code */
+#include <string.h> /* error strings */
+#include "Gapil.h"
+
+#define BACKLOG 10
+#define MAXLINE 256
+int demonize = 1; /* daemon use option: default is daemon */
+int debugging = 0; /* debug info printing option: default is no debug */
+/* Subroutines declaration */
+void usage(void);
+void ServEcho(int sockfd);
+void PrintErr(char * error);
+/* Program beginning */
+int main(int argc, char *argv[])
+{
+/*
+ * Variables definition
+ */
+ int list_fd, conn_fd;
+ int waiting = 0;
+ int compat = 0;
+ pid_t pid;
+ struct sockaddr_in serv_add, cli_add;
+ socklen_t len;
+ char debug[MAXLINE], ipaddr[20];
+ /*
+ * Input section: decode parameters passed in the calling
+ * Use getopt function
+ */
+ int i;
+ opterr = 0; /* don't want writing to stderr */
+ while ( (i = getopt(argc, argv, "hdicw:")) != -1) {
+ switch (i) {
+ /*
+ * Handling options
+ */
+ case 'h':
+ printf("Wrong -h option use\n");
+ usage();
+ return(0);
+ break;
+ case 'i':
+ demonize = 0;
+ break;
+ case 'c':
+ compat = 1;
+ break;
+ case 'd':
+ debugging = 1;
+ break;
+ case 'w':
+ waiting = strtol(optarg, NULL, 10);
+ break;
+ case '?': /* unrecognized options */
+ printf("Unrecognized options -%c\n",optopt);
+ usage();
+ default: /* should not reached */
+ usage();
+ }
+ }
+ /* ***********************************************************
+ *
+ * Options processing completed
+ *
+ * Main code beginning
+ *
+ * ***********************************************************/
+ /* Main code begin here */
+ if (compat) { /* install signal handler */
+ Signal(SIGCHLD, HandSigCHLD); /* non restarting handler */
+ } else {
+ SignalRestart(SIGCHLD, HandSigCHLD); /* restarting handler */
+ }
+ /* create socket */
+ if ( (list_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
+ perror("Socket creation error");
+ exit(1);
+ }
+ /* initialize address */
+ memset((void *)&serv_add, 0, sizeof(serv_add)); /* clear server address */
+ serv_add.sin_family = AF_INET; /* address type is INET */
+ serv_add.sin_port = htons(7); /* echo port is 7 */
+ serv_add.sin_addr.s_addr = htonl(INADDR_ANY); /* connect from anywhere */
+ /* bind socket */
+ if (bind(list_fd, (struct sockaddr *)&serv_add, sizeof(serv_add)) < 0) {
+ perror("bind error");
+ exit(1);
+ }
+ /* release privileges and go daemon */
+ if (setgid(65534) !=0) { /* first give away group privileges */
+ perror("cannot give away group privileges");
+ exit(1);
+ }
+ if (setuid(65534) !=0) { /* and only after user ... */
+ perror("cannot give away user privileges");
+ exit(1);
+ }
+ if (demonize) { /* go daemon */
+ openlog(argv[0], 0, LOG_DAEMON); /* open logging */
+ if (daemon(0, 0) != 0) {
+ perror("cannot start as daemon");
+ exit(1);
+ }
+ }
+ /* main body */
+ if (listen(list_fd, BACKLOG) < 0 ) {
+ PrintErr("listen error");
+ exit(1);
+ }
+ if (waiting) sleep(waiting);
+ /* handle echo to client */
+ while (1) {
+ /* accept connection */
+ while (((conn_fd = accept(list_fd, (struct sockaddr *)&cli_add, &len))
+ < 0) && (errno == EINTR));
+ if ( conn_fd < 0) {
+ PrintErr("accept error");
+ exit(1);
+ }
+ if (debugging) {
+ inet_ntop(AF_INET, &cli_add.sin_addr, ipaddr, sizeof(ipaddr));
+ snprintf(debug, MAXLINE, "Accepted connection form %s\n", ipaddr);
+ if (demonize) {
+ syslog(LOG_DEBUG, debug);
+ } else {
+ printf("%s", debug);
+ }
+ }
+ /* fork to handle connection */
+ if ( (pid = fork()) < 0 ){
+ PrintErr("fork error");
+ exit(1);
+ }
+ if (pid == 0) { /* child */
+ close(list_fd); /* close listening socket */
+ ServEcho(conn_fd); /* handle echo */
+ if (debugging) {
+ snprintf(debug, MAXLINE, "Closed connection %s\n", ipaddr);
+ if (demonize) {
+ syslog(LOG_DEBUG, debug);
+ } else {
+ printf("%s", debug);
+ }
+ }
+ exit(0);
+ } else { /* parent */
+ close(conn_fd); /* close connected socket */
+ }
+ }
+ /* normal exit, never reached */
+ exit(0);
+}
+/*
+ * routine to print usage info and exit
+ */
+void usage(void) {
+ printf("Elementary echo server\n");
+ printf("Usage:\n");
+ printf(" echod [-h] \n");
+ printf(" -h print this help\n");
+ printf(" -d write debug info\n");
+ printf(" -i use interactively\n");
+ printf(" -c disable BSD semantics\n");
+ printf(" -w N wait N sec. before calling accept\n");
+ exit(1);
+}
+/*
+ * routine to handle echo for connection
+ */
+void ServEcho(int sockfd) {
+ char buffer[MAXLINE];
+ int nread, nwrite;
+ char debug[MAXLINE+20];
+ /* main loop, reading 0 char means client close connection */
+ while ( (nread = read(sockfd, buffer, MAXLINE)) != 0) {
+ if (nread < 0) {
+ PrintErr("Errore in lettura");
+ return;
+ }
+ nwrite = FullWrite(sockfd, buffer, nread);
+ if (nwrite) {
+ PrintErr("Errore in scrittura");
+ return;
+ }
+ if (debugging) {
+ buffer[nread] = 0;
+ snprintf(debug, MAXLINE+20, "Letti %d byte, %s", nread, buffer);
+ if (demonize) { /* daemon mode */
+ syslog(LOG_DEBUG, debug);
+ } else {
+ printf("%s", debug);
+ }
+ }
+ }
+ return;
+}
+/*
+ * routine to print error on stout or syslog
+ */
+void PrintErr(char * error) {
+ if (demonize) { /* daemon mode */
+ syslog(LOG_ERR, "%s: %m", error); /* log string and error message */
+ } else {
+ perror(error);
+ }
+ return;
+}
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