strictmain.cpp

查看局域网的信息,类似网上邻居的功能,例如查看哪台计算机在线等

/*    strictmain.cpp
 *
 *    Copyright (c) 1998-2000 Alexander Neundorf
 *    [e-mail]
 *
 *    You may distribute under the terms of the GNU General Public
 *    License as specified in the COPYING file.
 *
 *    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.
 *
 */

#include "lisadefines.h"
#include "netmanager.h"

#include "getdebug.h"

#include <iostream.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>

// detect linux/glibc for the gnu style --args
#if defined(__linux__) || defined(__linux) || defined(linux)
#  include <features.h>
#  ifdef __GLIBC__
// only gnu libc has getopt.h... getopt(3) is defined to be in unistd.h
// by POSIX.2
#    define _GNU_SOURCE
#    include <getopt.h>
#  endif // __GLIBC__
#  define GNU_GETOPT
#endif // linux


void printVersion()
{
   const char * versionInfo=\
   "\nThis is the restricted LAN Information Server resLISa "MYVERSION"\n"\
   "It is free software according the GNU General Public License\n"\
   "Copyright (c) 2000 by Alexander Neundorf\n"\
   "email: [e-mail]\n";
   cout<<versionInfo<<endl;
};

void usage()
{
   printVersion();
   const char * usageInfo=\
      "-v, --version      prints out a short version info\n"\
      "-u, --unix         search at first for $HOME/.reslisarc, then\n"\
      "                   for /etc/reslisarc, this is the default behaviour\n"\
      "-k, --kde1         search at first for $HOME/.kde/share/config/reslisarc,\n"\
      "                   then for $KDEDIR/share/config/reslisarc\n"\
      "-K, --kde2         looks for the file reslisarc in every directory\n"\
      "                   returned by running \"kde-config --path config\"\n"\
      "-c, --config=FILE  read this and no other configuration file\n"\
      "-h, --help         you are currently reading it ;-)\n";
      cout<<usageInfo<<endl;
//I thought this would be the way to check wether long options are supported...
//#ifndef _GNU_SOURCE
//      cout<<"Please note that the long options are not supported on this system"<<endl;
//#endif
};

void destruct(int sigNumber)
{
   signal(sigNumber,SIG_IGN);
   cout<<"signal caught: "<<sigNumber<<", exiting"<<endl;
   //signal(sigNumber,&destruct);
   exit(0);
};

NetManager *manager(0);

void readConfig(int sigNumber)
{
   cout<<"readConfig(): signal caught: "<<sigNumber<<endl;
   signal(SIGHUP,SIG_IGN);
   if (manager!=0)
      manager->readConfig();
   signal(SIGHUP,&readConfig);
};

void printState(int sigNumber)
{
   cout<<"printState(): signal caught: "<<sigNumber<<endl;
   signal(SIGUSR1,SIG_IGN);
   if (manager!=0)
      manager->printState();
   signal(SIGUSR1,&printState);
};

void setSignalHandler()
{
   signal(SIGHUP,&readConfig);
	signal(SIGUSR1,&printState);

   signal(SIGINT,&destruct);
	signal(SIGQUIT,&destruct);
	signal(SIGILL,&destruct);
	signal(SIGTRAP,&destruct);
	signal(SIGABRT,&destruct);
	signal(SIGBUS,&destruct);
	signal(SIGSEGV,&destruct);
	signal(SIGUSR2,&destruct);
	signal(SIGPIPE,&destruct);
	signal(SIGALRM,&destruct);
	signal(SIGTERM,&destruct);
	signal(SIGFPE,&destruct);
#ifdef SIGPOLL
   signal(SIGPOLL, &destruct);
#endif
#ifdef SIGSYS
   signal(SIGSYS, &destruct);
#endif
#ifdef SIGVTALRM
   signal(SIGVTALRM, &destruct);
#endif
#ifdef SIGXCPU
   signal(SIGXCPU, &destruct);
#endif
#ifdef SIGXFSZ
   signal(SIGXFSZ, &destruct);
#endif
};

#ifdef GNU_GETOPT
static struct option const long_opts[] =
{
  {"version", no_argument, 0, 'v'},
  {"unix", no_argument, 0, 'u'},
  {"kde1", no_argument, 0, 'k'},
  {"kde2", no_argument, 0, 'K'},
  {"config", required_argument, 0, 'c'},
  {"help", no_argument, 0, 'h'},
  {0, 0, 0, 0}
};
#endif

int main(int argc, char** argv)
{
   int c(0);
   int configStyle(UNIXCONFIGSTYLE);
   MyString configFile;
   int portToUse(MYPORT);

//I thought this would be the way to check wether long options are supported...
#ifdef GNU_GETOPT
   while ((c=getopt_long(argc, argv, "vukKc:h", long_opts, 0))!=-1)
#else
   while ((c=getopt(argc, argv, "vukKc:h"))!=-1)
#endif
   {
      char **endp(0);
      switch (c)
      {
      case 0:
         break;
      case 'v':
         printVersion();
         exit(0);
         break;

      case 'u':
         configStyle = UNIXCONFIGSTYLE;
         break;

      case 'k':
         configStyle = KDE1CONFIGSTYLE;
         break;

      case 'K':
         configStyle = KDE2CONFIGSTYLE;
         break;

      case 'c':
         configFile = optarg;
         configStyle = EXTRACONFIGSTYLE;
         break;

      case 'h':
      default:
         usage();
         exit(0);
         break;
      }
   }

   //fork and let the parent exit
   pid_t pid=fork();
   if (pid>0)
   {
      //this is the parent
      exit(0);
   }
   else if (pid<0)
   {
      getDebug()<<"could not fork()"<<endl;
      exit(0);
   };
   //we will only read/write to/from this socket in the child process
   int rawSocket=socket(AF_INET,SOCK_RAW,IPPROTO_ICMP);
   if (rawSocket==-1)
   {
      cout<<"could not create raw socket, root privileges required"<<endl;
      cout<<"take a look at the README for more information"<<endl;
      exit(0);
   };
   int bufferSize(60*1024);
   int on(1);
   setsockopt(rawSocket,SOL_SOCKET,SO_RCVBUF,&bufferSize,sizeof(bufferSize));
   int result=setsockopt(rawSocket, SOL_SOCKET, SO_BROADCAST,&on, sizeof(on));
   getDebug()<<"main(): setsockopt returns "<<result<<endl;
   //dropping root privileges
   //they will be regained once in the child process
   //for creating a raw socket

   //now dropping root privileges once and ever
   //seteuid(getuid());
   setuid(getuid());
   
   //according to R. Stevens the following three lines 
   //make daemons feel good :)
   setsid();
   chdir("/");
   umask(0);
   
   getDebug()<<"main starting, dropped root privileges"<<endl;
   getDebug()<<"main(): port: "<<portToUse<<" file: "<<configFile<<endl;
   NetManager netmanager(rawSocket,portToUse,configFile,configStyle,1);
   manager=&netmanager;
   getDebug()<<"main: NetKnife created"<<endl;
   setSignalHandler();

   netmanager.readConfig();
   if (netmanager.prepare())
   {
      printVersion();
      netmanager.run();
   };
   getDebug()<<"main: server finished"<<endl;
}