how do I know if a server (on the box) is running?

Hi again,

Lately I'm doing socket programming, as far I can tell it works fine.
the problem is that how do I know if a server (on the box) is running.
The gethostbyname() will only detect if a IP address exist or is currently running.

The only idea that I have is, after gethostbyname() and a successful connect() my program will send some sort of message, then the (workspace)server will then send a valid response. If no valid response is recieve then the process will start all over again.

is this the way to go, just to know if a (workspace)server is running or there is another way ?

regards,
jaro

here is the code that I've done so far.

Code:

---

#include <stdio.h>
#include <winsock.h>

#define STRSIZE 16536

void handle_error(void);
void receiveMessage(void);
void connectToWorkSpace();


char recvbuf[60000] = "";
SOCKET ConnectSocket;
struct sockaddr_in clientService;

int bytesSent;
int bytesRecv = 0;
char sendbuf[500] = "";
 
struct hostent *h;
char HOSTNME[20]="";
char hostname[20] = "localhost";                        // for testing purposes
char hostnamebackup[20] = "local-blahblah";        // for testing purposes

int chker=0;

int main()
{
        connectToWorkSpace();               
               
                while(1){
                        receiveMessage();
                }

}


void receiveMessage()
{
        int bytesRecv = 0;


        bytesRecv = recv( ConnectSocket, recvbuf, 60000, 0 );

        // check if server is still up
        if (bytesRecv == 0 || 
                bytesRecv == SOCKET_ERROR ||
                WSAGetLastError() == WSAEINTR ||                /*(has been closed)*/
                WSAGetLastError() == WSAENOTCONN ||                /*(not connected)*/
                WSAGetLastError() == WSAENETRESET ||        /*(kepp-alive service failed and broke connection)*/
                WSAGetLastError() == WSAESHUTDOWN ||        /*(the socket was shutdown() peacefully)*/
                WSAGetLastError() == WSAECONNABORTED ||        /*(something died and the connection was broken)*/
                WSAGetLastError() == WSAETIMEDOUT ||        /*(the network died or the other computer stopped responding)*/
                WSAGetLastError() == WSAECONNRESET                /*(something died on the remote computer and broke the connection)*/
                ){
                        printf("Reconnect!\n");
                        connectToWorkSpace();
        }else{
                recvbuf[bytesRecv]='\0';
                        if(strlen(recvbuf)>0){
                                printf("received message: %s \n", recvbuf);
                        }
        }

}



void connectToWorkSpace()
{

int chkHost=0;
int loopHost=0;
int conn = 1;

        WSADATA wsaData;
        WORD wVersionRequested;             
        wVersionRequested = MAKEWORD( 1, 1 );


        if ( WSAStartup( wVersionRequested, &wsaData ) != 0 ){
                fprintf(stderr,"WSAStartup Error...");
                handle_error();
        }

        // will loop until connect() is successful
        while(conn != 0){

                chkHost =chker%2;

                if(chkHost == 0){
                        printf("Connect Using Primary Host\n");
                        strcpy(HOSTNME,hostname);
                }
                else {
                        printf("Connect Using Backup Host\n");
                        strcpy(HOSTNME,hostnamebackup);
                }

                // will loop until HOSTNME is reachable
                while(loopHost==0){
                        chkHost =chker%2;
                        if((h=gethostbyname(HOSTNME))==NULL)
                        {
                                        printf("%s not reachable\n",HOSTNME);
                                       
                                        if(chkHost == 1){
                                                printf("Connect Using Primary Host\n");
                                                strcpy(HOSTNME,hostname);
                                        }
                                        else {
                                                printf("Connect Using Backup Host\n");
                                                strcpy(HOSTNME,hostnamebackup);
                                        }
                                       
                        }else{
                                loopHost=1;
                        }
                        Sleep(1000);
                        chker++;
                }

                       

                clientService.sin_addr=*((struct in_addr*)h->h_addr);
                clientService.sin_port = htons(8770);
                clientService.sin_family = AF_INET;


                       
                // Create a SOCKET for connecting to server
                ConnectSocket = socket(AF_INET, SOCK_STREAM, 0);
                if (ConnectSocket == -1) {
                        handle_error();
                        printf("Error at socket(): \n");
                        //return -1;
                }

                // Connect
                if( connect( ConnectSocket, (struct sockaddr*) &clientService, sizeof(struct sockaddr) ) == -1) {
                        printf("Failed to connect. Workspaceserver is down.\n" );
                        printf("Reconnecting........\n" );                                                                               
                        loopHost=0;
                        Sleep(5000);       
                        conn = 1;
                }
                else {
                        conn = 0;
                        printf("Connection Success!\n");
                }

        }

        strcpy(sendbuf,"jaro");
        strcat(sendbuf, " :username");
        strcat(sendbuf, "\n");

        /* Send */
        bytesSent = send( ConnectSocket, sendbuf, strlen(sendbuf), 0 );
        printf( "\n messages Sent: %s\n", sendbuf );                               
}


void handle_error(void)
{
  /*
  * Errors are handled by calling the WSAGetLastError routine which
  * will return the last error as one of the following. As we develop
  * this tutorial, we will go into much more detail on what they mean
  * and what caused them.
  */
        int x;
        x= WSAGetLastError();

  switch ( x )
  {
    case WSANOTINITIALISED :
      printf("Unable to initialise socket.\n");
    break;
    case WSAEAFNOSUPPORT :
      printf("The specified address family is not supported.\n");
    break;
    case WSAEADDRNOTAVAIL :
      printf("Specified address is not available from the local machine.\n");
    break;
    case WSAECONNREFUSED :
      printf("The attempt to connect was forcefully rejected.\n");
      break;
    case WSAEDESTADDRREQ :
      printf("address destination address is required.\n");
    break;
    case WSAEFAULT :
      printf("The namelen argument is incorrect.\n");
    break;
    case WSAEINVAL :
      printf("The socket is not already bound to an address.\n");
    break;
    case WSAEISCONN :
      printf("The socket is already connected.\n");
    break;
    case WSAEADDRINUSE :
      printf("The specified address is already in use.\n");
    break;
    case WSAEMFILE :
      printf("No more file descriptors are available.\n");
    break;
    case WSAENOBUFS :
      printf("No buffer space available. The socket cannot be created.\n");
    break;
    case WSAEPROTONOSUPPORT :
      printf("The specified protocol is not supported.\n");
      break;
    case WSAEPROTOTYPE :
      printf("The specified protocol is the wrong type for this socket.\n");
    break;
    case WSAENETUNREACH :
      printf("The network can't be reached from this host at this time.\n");
    break;
    case WSAENOTSOCK :
      printf("The descriptor is not a socket.\n");
    break;
    case WSAETIMEDOUT :
      printf("Attempt timed out without establishing a connection.\n");
    break;
    case WSAESOCKTNOSUPPORT :
      printf("Socket type is not supported in this address family.\n");
    break;
    case WSAENETDOWN :
      printf("Network subsystem failure.\n");
    break;
    case WSAHOST_NOT_FOUND :
      printf("Authoritative Answer Host not found.\n");
    break;
    case WSATRY_AGAIN :
      printf("Non-Authoritative Host not found or SERVERFAIL.\n");
    break;
    case WSANO_RECOVERY :
      printf("Non recoverable errors, FORMERR, REFUSED, NOTIMP.\n");
    break;
    case WSANO_DATA :
      printf("Valid name, no data record of requested type.\n");
    break;
      case WSAEINPROGRESS :
      printf("address blocking Windows Sockets operation is in progress.\n");
    break;
    case WSAEINTR :
      printf("The (blocking) call was canceled via WSACancelBlockingCall().\n");
    break;
    default :
      printf("Unknown error.\n");
    break;
  }

}

---

Just need some comment (good or bad) on the program that I've written. Just need to know if I'm on the right track.

regards,
jaro

Let me understand, you have some kind of a remote server, running some sort of protocol on a defined port; And you want to check if the server application is really running and not just the computer pluged in? Am I right?

Then yeah, sure the best way is to attempt to connect the server.
Connect the server's port just to see if it allows you to establish a connection, I think this should be enough.


----------
please move the topic to Network Programming


thank you.