Server Problem !! (I hate C++)

Hi everyone,

Sorry for my title, But This language make me cold to programming language.I was a succesful programmer but C++ uwww its horrible..

Anyway, I have a course that is Operational System.. My lecturer doesnt explain sso much and after He say, You must solve this problem, because u r a programmer.. I havent information about linux programmin and I cant.. I am good in c#,vb.neteven java ... anyway

I put my codes here, He wants, I must allow multi-client to server. It means, server must accept all clients that request..And also server can send value which clients connected And I must use fork. I tried some ways but no successful. And also he said, you must edit my server codes, you cant own code.

I attached server&client file here. Can u say where is my problem?

this is just main function

Code:

---

int main( int argn, char **arg )
{
  if ( argn <= 1 ) help( *arg );

  int port = 0;

  // zpracovani prikazoveho radku
  for ( int i = 1; i < argn; i++ )
  {
      if ( !strcmp( arg[ i ], "-d" ) )
          debug = 1;

      if ( !strcmp( arg[ i ], "-h" ) )
          help( *arg );

      if ( *arg[ i ] != '-' && !port )
      {
          port = atoi( arg[ i ] );
          break;
      }
  }

  if ( !port )
  {
      zprava( ZPR_INFO, "Chybejici nebo spatne cislo portu!" );
      help( *arg);
  }

  zprava( ZPR_INFO, "Server bude poslouchat na portu: %d.", port );

  // vytvoreni socketu
  int sock_listen = socket( AF_INET, SOCK_STREAM, 0 );
  if ( sock_listen == -1 )
  {
      zprava( ZPR_CHYBA, "Nelze vytvorit socket.");
      exit( 1 );
  }

  in_addr addr_any = { INADDR_ANY };
  sockaddr_in srv_addr;
  srv_addr.sin_family = AF_INET;
  srv_addr.sin_port = htons( port );
  srv_addr.sin_addr = addr_any;

  // socket smi znovu okamzite pouzit jiz drive pouzite cislo portu
  int opt = 1;
  if ( setsockopt( sock_listen, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof( opt ) ) < 0 )
      zprava( ZPR_CHYBA, "Nelze nastavit vlastnosti socketu." );

  // prirazeni adresy a portu socketu
  if ( bind( sock_listen, (const sockaddr * ) &srv_addr, sizeof( srv_addr ) ) < 0 )
  {
      zprava( ZPR_CHYBA, "Prirazeni adresy selhalo." );
      close( sock_listen );
      exit( 1 );
  }

  // aplikace bude naslouchat na zadanem portu
  if ( listen( sock_listen, 1 ) < 0 )
  {
      zprava( ZPR_CHYBA, "Nelze naslouchat na pozadovanem portu." );
      close( sock_listen );
      exit( 1 );
  }

  int sock_client = 0;

  // jedeme!

  while ( 1 )
  {



      char buf[ 100 ];

      // mnozina hadlu
      fd_set read_wait_set;
      // vynulovani mnoziny
      FD_ZERO( &read_wait_set );

      // pridani handlu stdin
      FD_SET( STDIN_FILENO, &read_wait_set );

      // vyber handlu - listen nebo spojeni se serverem?
      // cekame na spojeni, nebo na data od serveru?


      if ( sock_client )
          {
              FD_SET( sock_client, &read_wait_set );


          }


      else
      {

          FD_SET( sock_listen, &read_wait_set );

      //    fork();
      }

      // cekame na data u nektereho handlu
      if ( select( MAX( sock_client, sock_listen ) + 1,
                          &read_wait_set, 0, 0, 0 ) < 0 ) break;




      // data na stdin?
      if ( FD_ISSET( STDIN_FILENO, &read_wait_set ) )
      {
          // cteme data ze stdin



          int l = read( STDIN_FILENO, buf, sizeof( buf ) );
          if ( l < 0 )
              zprava( ZPR_CHYBA, "Nelze cist data ze stdin." );
          else
              zprava( ZPR_LADENI, "Nacteno %d bytu ze stdin.", l );

          // posleme data klientovi
          l = write( sock_client, buf, l );
          if ( l < 0 )
              zprava( ZPR_CHYBA, "Nelze zaslat data klientovi." );
          else
              zprava( ZPR_LADENI, "Odeslano %d bytu klientovi.", l );
      }


      else if ( FD_ISSET( sock_listen, &read_wait_set ) )
      {
          sockaddr_in rsa;

          int rsa_size = sizeof( rsa );

          // prijmeme nove spojeni
          sock_client = accept( sock_listen, ( sockaddr * ) &rsa, ( socklen_t * ) &rsa_size );

          if ( sock_client == -1 )
          {
              zprava( ZPR_CHYBA, "Spojeni se nezdarilo." );
              close( sock_listen );
              exit( 1 );
          }


        if (fork() !=0)
        {
        close (sock_client);
        continue;
        }

        else {

        if (fork() == 0)
        {


          uint lsa = sizeof( srv_addr );

          // ziskani vlastni IP
          getsockname( sock_client, ( sockaddr * ) &srv_addr, &lsa );

          zprava( ZPR_INFO, "Moje IP: '%s'  port: %d",
                  inet_ntoa( srv_addr.sin_addr ), ntohs( srv_addr.sin_port ) );

          // ziskani IP klienta
          getpeername( sock_client, ( sockaddr * ) &srv_addr, &lsa );

          zprava( ZPR_INFO, "Klient IP: '%s'  port: %d",
                  inet_ntoa( srv_addr.sin_addr ), ntohs( srv_addr.sin_port ) );

          zprava( ZPR_INFO, "Zadejte 'quit' pro ukonceni procesu serveru." );
        }

 

        }
          }
    }




      // data od klienta?
      else if ( FD_ISSET( sock_client, &read_wait_set ) )
      {

          // precteme data od klienta
          int l = read( sock_client, buf, sizeof( buf ) );
          if ( !l )
          {
              zprava( ZPR_LADENI, "Klient uzavrel spojeni." );
              close( sock_client );
              sock_client = 0;
              break;
          }
          else if ( l < 0 )
              zprava( ZPR_LADENI, "Nelze precist data od klienta." );
          else
              zprava( ZPR_LADENI, "Precteno %d bytu od klienta.", l );

          // vsechna data na stdout
          l = write( STDOUT_FILENO, buf, l );
          if ( l < 0 )
              zprava( ZPR_CHYBA, "Nelze zapsat na stdout." );

          // konrola, zda klient nezada o ukonceni spojeni
          if ( !strncasecmp( buf, "close", 5 ) )
          {
              zprava( ZPR_INFO, "Klient zaslal 'close' pozadavek, ukoncujeme spojeni." );
              zprava( ZPR_INFO, "Cekame na pripojeni noveho klienta." );
              close( sock_client );
              sock_client = 0;
          }

      }


      // byl pozadavek na ukonceni prace serveru?
      if ( !strncasecmp( buf, "quit", 4 ) )
      {
          close( sock_client );
          zprava( ZPR_INFO, "Byl zadan pozadavek 'quit'. Server konci svou cinnost.\n" );
          break;
      }


  }

  close( sock_listen );

  return 0;
}

---

Please help me, I dont want to fail this course.. I'm an erasmus student also...

Quote:

---

Originally Posted by ertan2002

I must allow multi-client to server. It means, server must accept all clients that request..And also server can send value which clients connected And I must use fork. I tried some ways but no successful.

I attached server&client file here. Can u say where is my problem?

---

Which problem? Perhaps you should think about them one at a time.

How To Ask Questions The Smart Way

Code:

---

        if (fork() !=0)
        {
        close (sock_client);
        continue;
        }

        else {

        if (fork() == 0)

---

Well the first problem is you're calling fork() twice, so you're getting more child processes than you think.

It should be

Code:

---

pid = fork();
if ( pid == 0 ) {
  // child, close listener socket, deal with client socket
} else if ( pid > 0 ) {
  // parent, close client socket, do whatever
} else {
  // panic
}

---

Also, it seems that both parent and child seem to make use of sock_client, and I can see that leading to confusion.
For one thing, the server will only deal with the last connected client.

The problem isn't as much C++ as your teacher's code. C++ is not a bad language, albeit network programming can be a pain.
In short, blame your teacher, not the language.