how to accept multiple clients with a simple winsock tcp server? - c++

Question

I can't figure out how to accept multiple connections for a simple tcp server using winsock.
I've tried a couple different ways and I can't figure out how to get another connection to work. The first call to accept() seems to be the only one that works. Can someone provide a simple example of how to do this or explain what's going on with listen() and accept() here?
#include <string>
#include <Winsock2.h>
WSADATA WsaData;
unsigned char packet_in[64];
unsigned short port = 29992;
unsigned int max_packet_size = sizeof(packet_in);
sockaddr_in xaddress;
SOCKET sock;
SOCKET sock1 = INVALID_SOCKET;
SOCKET sock2 = INVALID_SOCKET;
int main()
{
int r = WSAStartup( MAKEWORD(2,2), &WsaData );
xaddress.sin_family = AF_INET;
xaddress.sin_port = htons(port);
DWORD nonBlocking = 1;
sockaddr_in from;
int fromLength = sizeof( from );
int count = 0;
sock = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
r = bind(sock, (const sockaddr*) &xaddress, sizeof(sockaddr_in));
if (r != 0) printf("%d\n", WSAGetLastError());
r = listen(sock, SOMAXCONN);
if (r == SOCKET_ERROR)
printf("%d\n",WSAGetLastError());
ioctlsocket(sock, FIONBIO, &nonBlocking);
while(true)
{
if(count == 0)
{
sock1 = accept(sock, NULL, NULL);
}
else if (count == 1)
{
sock2 = accept(sock, NULL, NULL);
}
if(sock1 != INVALID_SOCKET)
count = 1;
if(sock2 != INVALID_SOCKET)
count = 2;
printf("%i\n",count);
}
return 0;
}

Answer 1

I don't know how to network programming on Windows, but it basically looks like on Linux, so this is small example for Linux.
struct sockaddr_in server_addr
socklen_t len = sizeof(server_addr);
...
while(1)
{
struct sockaddr_in client_addr;
int client_fd;
if((client_fd = accept(server_sock, (struct sockaddr*)& client_addr, &len)) < 0)
{
cerr<<"accept() error"<<endl;
continue;
}
...
}
There is full example written in Polish, but you should understand:
full example (find //server.c)
Main differences between network programming on Windows and Linux are structures and classes, so it should give you some knowledge: Beej's guide to network programming

Answer 2

I think from this simple program, You will get better idea :)
// Multi-Client - Server chat application
#include"header.h"
void isr(int n)
{
printf("Client is Disconnected ..\n");
kill(getpid(),9);
return;
}
main()
{
int sockfd,nsfd,len,pid,size;
char buffer[500],buffer1[500];
struct sockaddr_in server;
///////////////////////////////////////////////////////////////////////
sockfd=socket(AF_INET,SOCK_STREAM,0);
if(sockfd==0)
{
printf("Socket file is not created socket is fail...\n");
return;
}
////////////////////////////////////////////////////////////////////////
server.sin_family=AF_INET;
server.sin_port=htons(9898);
len = sizeof(server);
/////////////////////////////////////////////////////////////////////
bind(sockfd,(struct sockaddr*)&server,len);
perror("bind");
/////////////////////////////////////////////////////////////
listen(sockfd,5);
perror("listen");
/////////////////////////////////////////////////////////////////
bzero(buffer,sizeof(buffer));
zero(buffer1,sizeof(buffer1));
//////////////////////////////////////////////////////////////////////
while(1)
{
nsfd=accept(sockfd,(struct sockaddr *)&server,&len);
if(nsfd<0)
{
perror("accept");
return;
}
if(fork()==0)
{
while(1)
{
size=recv(nsfd,buffer,sizeof(buffer),0);
if(size==0)
{
printf("Server is Disconnected...\n");
return;
}
printf("Data:%s\n",buffer);
bzero(buffer,sizeof(buffer));
}
}
else
{
printf("Enter the massage:\n");
signal(17,isr);
while(1)
{
gets(buffer);
send(nsfd,buffer,strlen(buffer)+1,0);
bzero(buffer,sizeof(buffer));
}
}
}
}