Programming Forums > Application Development > C++

LOI Kratong · Sep 28th, 2005, 3:51 PM

How is it possible to contact other computers over a small network? Can someone point me to a tutorial or a website where i can learn? Basically i want several computers in a network to contact a 'server' designated computer and for that server to respond with some information.

Anyone know how i can learn?

Ooble · Sep 28th, 2005, 3:58 PM

Beej's Guide is considered by many to be the tutorial for beginning networking.

nnxion · Sep 28th, 2005, 4:09 PM

That's where I began

Infinite Recursion · Sep 28th, 2005, 9:26 PM

Review sockets, tcp/ip, udp, etc...

Yep, that tutorial was one of many that I read when I first got started.

LOI Kratong · Oct 2nd, 2005, 7:01 AM

Thanks guys that really helped. I've read the whole lot and basically understood it, but i'm on a windows box and i'm not sure where to put the code that he suggests...

(Toggle Plain Text)

{
    WSADATA wsaData;   // if this doesn't work
    //WSAData wsaData; // then try this instead

    if (WSAStartup(MAKEWORD(1, 1), &wsaData) != 0) {
        fprintf(stderr, "WSAStartup failed.\n");
        exit(1);
    }

DaWei · Oct 2nd, 2005, 7:30 AM

Beej is good. Go to MSDN also, since you're on Windows. Their examples will show you. I would also suggest you use winsock2 instead of the older winsock. If you can't find things by googling or searching MSDN, post back. I have a couple samples, and I believe there are probably a couple posts on the forum.

LOI Kratong · Oct 2nd, 2005, 8:14 AM

I've had a look.

I got this half-tute on MSDN:
http://msdn.microsoft.com/library/de...th_winsock.asp
but it was more confusing than Beej so i'm not too keen on continuing with it.

I'm finding it hard to find examples. Do you have any working windows ones?

The whole subject area seems really interesting but a bit tricky to wet up...

DaWei · Oct 2nd, 2005, 8:25 AM

As you can see, the initialization occurs the very first thing. That shouldn't be too surprising, since it's initialization. I don't want to appear too abrupt, but the ability to research and investigate these things, rather than ask for working examples, is key to being a successful programer. I know that MSDN, particularly, can be hard to navigate, but difficult things must be done by SOMEONE, and self-reliance is a nice employee trait.

(Toggle Plain Text)

int main (void)
{
   // Initialize Winsock.
   WSADATA wsaData;
   SOCKADDR_IN clientService;
   SOCKET uipSocket;
   int i;
   int bytesSent; 
   int bytesRecv;
   char sendbuf[32];
   char recvbuf[32];

   unsigned us;
   us = -1;
   std::cout << hex << us << endl;

   if (WSAStartup (MAKEWORD (2, 2), &wsaData)) return opAdvisory ("Socket startup failed\n");
   uipSocket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
   if ( uipSocket == INVALID_SOCKET )
   {
      WSACleanup();
      return opAdvisory ("Socket error\n");
   }

LOI Kratong · Oct 2nd, 2005, 10:23 AM

Yeah i completely understand and agree with, but thanks for the help. I did find my own workin example aswell (you'll be glad to know) so i think that i have i cracked... Well sort of

Cheers!

LOI Kratong · Oct 2nd, 2005, 11:18 AM

Well i said i cracked it but i'm back!

I have it communicating over my local box, how would i extend it over a local wired network, for example the on at my school

Code for the 'server' part of the program:

(Toggle Plain Text)

#include <stdio.h>
#include <iostream>
#include "winsock2.h"

using namespace std;

int main() {

    // Initialize Winsock.
    WSADATA wsaData;
    int iResult = WSAStartup( MAKEWORD(2,2), &wsaData );
    if ( iResult != NO_ERROR )
       cout << "Error at WSAStartup()\n";

    // Create a socket.
    SOCKET m_socket;
    m_socket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );

    if ( m_socket == INVALID_SOCKET ) {
        cout << "Error at socket(): \n"; 
        cout << WSAGetLastError();
        WSACleanup();
        return 0;
    }

    // Bind the socket.
    sockaddr_in service;

    service.sin_family = AF_INET;
    service.sin_addr.s_addr = inet_addr( "127.0.0.1" );
    service.sin_port = htons( 27015 );

    if ( bind( m_socket, (SOCKADDR*) &service, sizeof(service) ) == SOCKET_ERROR ) {
        cout << "bind() failed.\n";
        closesocket(m_socket);
        return 0;
    }
    
    // Listen on the socket.
    if ( listen( m_socket, 1 ) == SOCKET_ERROR )
        cout << "Error listening on socket.\n";

    // Accept connections.
    SOCKET AcceptSocket;

    cout << "Waiting for a client to connect...\n";
    while (1) {
        AcceptSocket = SOCKET_ERROR;
        while ( AcceptSocket == SOCKET_ERROR ) {
            AcceptSocket = accept( m_socket, NULL, NULL );
        }
        cout << "Client Connected.\n";
        m_socket = AcceptSocket; 
        break;
    }
    
    // Send and receive data.
    int bytesSent;
    int bytesRecv = SOCKET_ERROR;
    char sendbuf[32];
    char recvbuf[32] = "";
    
    bytesRecv = recv( m_socket, recvbuf, 32, 0 );
    cout << "Bytes Recv: " << bytesRecv << "\n" ;
    
    for (int i = 0; i <= 32; i++)
    {
        sendbuf[i] = recvbuf[i];
    }
    
    bytesSent = send( m_socket, sendbuf, strlen(sendbuf), 0 );
    cout << "Bytes Sent: " << bytesSent << "\n\n\n";
    cout << recvbuf << "\n\n" ;
    system ("PAUSE");
    return 0;
}

Code for the actual 'messenger' part:

(Toggle Plain Text)

#include <stdio.h>
#include <iostream>
#include "winsock2.h"

using namespace std;

int main() {

    // Initialize Winsock.
    WSADATA wsaData;
    int iResult = WSAStartup( MAKEWORD(2,2), &wsaData );
    if ( iResult != NO_ERROR )
        cout << "Error at WSAStartup()\n";

    // Create a socket.
    SOCKET m_socket;
    m_socket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );

    if ( m_socket == INVALID_SOCKET ) {
        cout << "Error at socket(): \n" << WSAGetLastError();
        WSACleanup();
        return 0;
    }

    // Connect to a server.
    sockaddr_in clientService;

    clientService.sin_family = AF_INET;
    clientService.sin_addr.s_addr = inet_addr( "127.0.0.1" );
    clientService.sin_port = htons( 27015 );

    if ( connect( m_socket, (SOCKADDR*) &clientService, sizeof(clientService) ) == SOCKET_ERROR) {
        cout << "Failed to connect.\n";
        WSACleanup();
        return 0;
    }

    // Send and receive data.
    int bytesSent;
    int bytesRecv = SOCKET_ERROR;
    char sendbuf[32] = "";
    char recvbuf[32] = "";

    //cin.sync;
    cout << " Enter what you want to appear on the server\n>";
    //getline(cin,sendbuf); 
    cin >> sendbuf;
    bytesSent = send( m_socket, sendbuf, strlen(sendbuf), 0 );
    cout << "Bytes Sent:" << bytesSent ;

    while( bytesRecv == SOCKET_ERROR ) {
       bytesRecv = recv( m_socket, recvbuf, 32, 0 );
       if ( bytesRecv == 0 || bytesRecv == WSAECONNRESET ) {
           cout << "Connection Closed.\n";
           break;
        }
        if (bytesRecv < 0)
            return 0;
        cout << "Bytes Recv: " << bytesRecv << "\n\n";
    }
    system ("PAUSE");
    return 0;
}

Basically i'm always logged onto the same box at school, so the ip address of the server would stay the same, but i want other people to open the messenger bit, type something and it appear on my screen.

I know i have to change the ip addresses but doesn't anyone know which one corresponds to which box?

Sorry to keep posting but i'm really interested in this stuff...

Sep 28th, 2005, 3:51 PM	#1
LOI Kratong Professional Programmer Join Date: May 2005 Location: Woo - Boot Sector! Posts: 294 Rep Power: 4	contacting computers over a network How is it possible to contact other computers over a small network? Can someone point me to a tutorial or a website where i can learn? Basically i want several computers in a network to contact a 'server' designated computer and for that server to respond with some information. Anyone know how i can learn? __________________ www.heldtogether.co.uk

Sep 28th, 2005, 3:58 PM	#2
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	Beej's Guide is considered by many to be the tutorial for beginning networking. __________________ Me :: You :: Them

Sep 28th, 2005, 4:09 PM	#3
nnxion Programming Guru Join Date: Jun 2005 Location: elemental plane Posts: 1,429 Rep Power: 5	That's where I began __________________ "Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for." -- Socrates

Sep 28th, 2005, 9:26 PM	#4
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,467 Rep Power: 8	Review sockets, tcp/ip, udp, etc... Yep, that tutorial was one of many that I read when I first got started. __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

Oct 2nd, 2005, 7:01 AM	#5
LOI Kratong Professional Programmer Join Date: May 2005 Location: Woo - Boot Sector! Posts: 294 Rep Power: 4	Thanks guys that really helped. I've read the whole lot and basically understood it, but i'm on a windows box and i'm not sure where to put the code that he suggests... (Toggle Plain Text) { WSADATA wsaData; // if this doesn't work //WSAData wsaData; // then try this instead if (WSAStartup(MAKEWORD(1, 1), &wsaData) != 0) { fprintf(stderr, "WSAStartup failed.\n"); exit(1); } { WSADATA wsaData; // if this doesn't work //WSAData wsaData; // then try this instead if (WSAStartup(MAKEWORD(1, 1), &wsaData) != 0) { fprintf(stderr, "WSAStartup failed.\n"); exit(1); } __________________ www.heldtogether.co.uk

Oct 2nd, 2005, 7:30 AM	#6
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Beej is good. Go to MSDN also, since you're on Windows. Their examples will show you. I would also suggest you use winsock2 instead of the older winsock. If you can't find things by googling or searching MSDN, post back. I have a couple samples, and I believe there are probably a couple posts on the forum. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Oct 2nd, 2005, 8:14 AM	#7
LOI Kratong Professional Programmer Join Date: May 2005 Location: Woo - Boot Sector! Posts: 294 Rep Power: 4	I've had a look. I got this half-tute on MSDN: http://msdn.microsoft.com/library/de...th_winsock.asp but it was more confusing than Beej so i'm not too keen on continuing with it. I'm finding it hard to find examples. Do you have any working windows ones? The whole subject area seems really interesting but a bit tricky to wet up... __________________ www.heldtogether.co.uk

Oct 2nd, 2005, 8:25 AM	#8
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	As you can see, the initialization occurs the very first thing. That shouldn't be too surprising, since it's initialization. I don't want to appear too abrupt, but the ability to research and investigate these things, rather than ask for working examples, is key to being a successful programer. I know that MSDN, particularly, can be hard to navigate, but difficult things must be done by SOMEONE, and self-reliance is a nice employee trait. (Toggle Plain Text) int main (void) { // Initialize Winsock. WSADATA wsaData; SOCKADDR_IN clientService; SOCKET uipSocket; int i; int bytesSent; int bytesRecv; char sendbuf[32]; char recvbuf[32]; unsigned us; us = -1; std::cout << hex << us << endl; if (WSAStartup (MAKEWORD (2, 2), &wsaData)) return opAdvisory ("Socket startup failed\n"); uipSocket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP ); if ( uipSocket == INVALID_SOCKET ) { WSACleanup(); return opAdvisory ("Socket error\n"); } int main (void) { // Initialize Winsock. WSADATA wsaData; SOCKADDR_IN clientService; SOCKET uipSocket; int i; int bytesSent; int bytesRecv; char sendbuf[32]; char recvbuf[32]; unsigned us; us = -1; std::cout << hex << us << endl; if (WSAStartup (MAKEWORD (2, 2), &wsaData)) return opAdvisory ("Socket startup failed\n"); uipSocket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP ); if ( uipSocket == INVALID_SOCKET ) { WSACleanup(); return opAdvisory ("Socket error\n"); } __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Oct 2nd, 2005, 10:23 AM	#9
LOI Kratong Professional Programmer Join Date: May 2005 Location: Woo - Boot Sector! Posts: 294 Rep Power: 4	Yeah i completely understand and agree with, but thanks for the help. I did find my own workin example aswell (you'll be glad to know) so i think that i have i cracked... Well sort of Cheers! __________________ www.heldtogether.co.uk

Oct 2nd, 2005, 11:18 AM	#10
LOI Kratong Professional Programmer Join Date: May 2005 Location: Woo - Boot Sector! Posts: 294 Rep Power: 4	Well i said i cracked it but i'm back! I have it communicating over my local box, how would i extend it over a local wired network, for example the on at my school Code for the 'server' part of the program: (Toggle Plain Text) #include <stdio.h> #include <iostream> #include "winsock2.h" using namespace std; int main() { // Initialize Winsock. WSADATA wsaData; int iResult = WSAStartup( MAKEWORD(2,2), &wsaData ); if ( iResult != NO_ERROR ) cout << "Error at WSAStartup()\n"; // Create a socket. SOCKET m_socket; m_socket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP ); if ( m_socket == INVALID_SOCKET ) { cout << "Error at socket(): \n"; cout << WSAGetLastError(); WSACleanup(); return 0; } // Bind the socket. sockaddr_in service; service.sin_family = AF_INET; service.sin_addr.s_addr = inet_addr( "127.0.0.1" ); service.sin_port = htons( 27015 ); if ( bind( m_socket, (SOCKADDR) &service, sizeof(service) ) == SOCKET_ERROR ) { cout << "bind() failed.\n"; closesocket(m_socket); return 0; } // Listen on the socket. if ( listen( m_socket, 1 ) == SOCKET_ERROR ) cout << "Error listening on socket.\n"; // Accept connections. SOCKET AcceptSocket; cout << "Waiting for a client to connect...\n"; while (1) { AcceptSocket = SOCKET_ERROR; while ( AcceptSocket == SOCKET_ERROR ) { AcceptSocket = accept( m_socket, NULL, NULL ); } cout << "Client Connected.\n"; m_socket = AcceptSocket; break; } // Send and receive data. int bytesSent; int bytesRecv = SOCKET_ERROR; char sendbuf[32]; char recvbuf[32] = ""; bytesRecv = recv( m_socket, recvbuf, 32, 0 ); cout << "Bytes Recv: " << bytesRecv << "\n" ; for (int i = 0; i <= 32; i++) { sendbuf[i] = recvbuf[i]; } bytesSent = send( m_socket, sendbuf, strlen(sendbuf), 0 ); cout << "Bytes Sent: " << bytesSent << "\n\n\n"; cout << recvbuf << "\n\n" ; system ("PAUSE"); return 0; } #include <stdio.h> #include <iostream> #include "winsock2.h" using namespace std; int main() { // Initialize Winsock. WSADATA wsaData; int iResult = WSAStartup( MAKEWORD(2,2), &wsaData ); if ( iResult != NO_ERROR ) cout << "Error at WSAStartup()\n"; // Create a socket. SOCKET m_socket; m_socket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP ); if ( m_socket == INVALID_SOCKET ) { cout << "Error at socket(): \n"; cout << WSAGetLastError(); WSACleanup(); return 0; } // Bind the socket. sockaddr_in service; service.sin_family = AF_INET; service.sin_addr.s_addr = inet_addr( "127.0.0.1" ); service.sin_port = htons( 27015 ); if ( bind( m_socket, (SOCKADDR) &service, sizeof(service) ) == SOCKET_ERROR ) { cout << "bind() failed.\n"; closesocket(m_socket); return 0; } // Listen on the socket. if ( listen( m_socket, 1 ) == SOCKET_ERROR ) cout << "Error listening on socket.\n"; // Accept connections. SOCKET AcceptSocket; cout << "Waiting for a client to connect...\n"; while (1) { AcceptSocket = SOCKET_ERROR; while ( AcceptSocket == SOCKET_ERROR ) { AcceptSocket = accept( m_socket, NULL, NULL ); } cout << "Client Connected.\n"; m_socket = AcceptSocket; break; } // Send and receive data. int bytesSent; int bytesRecv = SOCKET_ERROR; char sendbuf[32]; char recvbuf[32] = ""; bytesRecv = recv( m_socket, recvbuf, 32, 0 ); cout << "Bytes Recv: " << bytesRecv << "\n" ; for (int i = 0; i <= 32; i++) { sendbuf[i] = recvbuf[i]; } bytesSent = send( m_socket, sendbuf, strlen(sendbuf), 0 ); cout << "Bytes Sent: " << bytesSent << "\n\n\n"; cout << recvbuf << "\n\n" ; system ("PAUSE"); return 0; } Code for the actual 'messenger' part: (Toggle Plain Text) #include <stdio.h> #include <iostream> #include "winsock2.h" using namespace std; int main() { // Initialize Winsock. WSADATA wsaData; int iResult = WSAStartup( MAKEWORD(2,2), &wsaData ); if ( iResult != NO_ERROR ) cout << "Error at WSAStartup()\n"; // Create a socket. SOCKET m_socket; m_socket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP ); if ( m_socket == INVALID_SOCKET ) { cout << "Error at socket(): \n" << WSAGetLastError(); WSACleanup(); return 0; } // Connect to a server. sockaddr_in clientService; clientService.sin_family = AF_INET; clientService.sin_addr.s_addr = inet_addr( "127.0.0.1" ); clientService.sin_port = htons( 27015 ); if ( connect( m_socket, (SOCKADDR) &clientService, sizeof(clientService) ) == SOCKET_ERROR) { cout << "Failed to connect.\n"; WSACleanup(); return 0; } // Send and receive data. int bytesSent; int bytesRecv = SOCKET_ERROR; char sendbuf[32] = ""; char recvbuf[32] = ""; //cin.sync; cout << " Enter what you want to appear on the server\n>"; //getline(cin,sendbuf); cin >> sendbuf; bytesSent = send( m_socket, sendbuf, strlen(sendbuf), 0 ); cout << "Bytes Sent:" << bytesSent ; while( bytesRecv == SOCKET_ERROR ) { bytesRecv = recv( m_socket, recvbuf, 32, 0 ); if ( bytesRecv == 0 \|\| bytesRecv == WSAECONNRESET ) { cout << "Connection Closed.\n"; break; } if (bytesRecv < 0) return 0; cout << "Bytes Recv: " << bytesRecv << "\n\n"; } system ("PAUSE"); return 0; } #include <stdio.h> #include <iostream> #include "winsock2.h" using namespace std; int main() { // Initialize Winsock. WSADATA wsaData; int iResult = WSAStartup( MAKEWORD(2,2), &wsaData ); if ( iResult != NO_ERROR ) cout << "Error at WSAStartup()\n"; // Create a socket. SOCKET m_socket; m_socket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP ); if ( m_socket == INVALID_SOCKET ) { cout << "Error at socket(): \n" << WSAGetLastError(); WSACleanup(); return 0; } // Connect to a server. sockaddr_in clientService; clientService.sin_family = AF_INET; clientService.sin_addr.s_addr = inet_addr( "127.0.0.1" ); clientService.sin_port = htons( 27015 ); if ( connect( m_socket, (SOCKADDR) &clientService, sizeof(clientService) ) == SOCKET_ERROR) { cout << "Failed to connect.\n"; WSACleanup(); return 0; } // Send and receive data. int bytesSent; int bytesRecv = SOCKET_ERROR; char sendbuf[32] = ""; char recvbuf[32] = ""; //cin.sync; cout << " Enter what you want to appear on the server\n>"; //getline(cin,sendbuf); cin >> sendbuf; bytesSent = send( m_socket, sendbuf, strlen(sendbuf), 0 ); cout << "Bytes Sent:" << bytesSent ; while( bytesRecv == SOCKET_ERROR ) { bytesRecv = recv( m_socket, recvbuf, 32, 0 ); if ( bytesRecv == 0 \|\| bytesRecv == WSAECONNRESET ) { cout << "Connection Closed.\n"; break; } if (bytesRecv < 0) return 0; cout << "Bytes Recv: " << bytesRecv << "\n\n"; } system ("PAUSE"); return 0; } Basically i'm always logged onto the same box at school, so the ip address of the server would stay the same, but i want other people to open the messenger bit, type something and it appear on my screen. I know i have to change the ip addresses but doesn't anyone know which one corresponds to which box? Sorry to keep posting but i'm really interested in this stuff... __________________ www.heldtogether.co.uk

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Programming Forums > Application Development > C++

contacting computers over a network