Question

My terminal keep create and forking . I think i did something wrong in my code, i actually want fork when client connect, but when i launch the server, its sort of keep forking as i check with linux command “ps” ,how do i change my code to make it work properly.

#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/un.h>
#include <sys/types.h>
#include <sys/socket.h>


using namespace std;

int main()
{

int serverFd;
int clientFd;
int serverLen;
int clientLen;
string message;
string serverSockAddrPtr;
struct sockaddr* serverSockAddressPnt;
struct sockaddr* clientSockAddressPnt;
struct sockaddr_un serverAddress;
struct sockaddr_un clientAddress;


// SOCKET CREATION PART - SERVER
serverFd = socket (AF_LOCAL, SOCK_STREAM, 0);

/* Set domain type */
serverAddress.sun_family = AF_LOCAL; 

/* Set name */ 
strcpy (serverAddress.sun_path, "CountryServer"); 


/* GET SIZE OF Server Addres */
serverLen = sizeof serverAddress;
/* GET SIZE OF Client Addres */
clientLen = sizeof clientAddress;

/* Get Server Sock Address Pointer*/
serverSockAddressPnt = (struct sockaddr *) &serverAddress; 
/* Get Client Sock Address Pointer*/
clientSockAddressPnt = (struct sockaddr *) &clientAddress; 

/* Create file */
bind (serverFd, serverSockAddressPnt , serverLen);

/* listen for connection */
listen (serverFd,5);

// SOCKET CREATION END - SERVER


while(1)
{
//accept client connection
clientFd = accept(serverFd, clientSockAddressPnt, (socklen_t*)&clientLen);

if(fork()==0)
{
message="Successfully connected to the server";
write(clientFd,message.c_str(),strlen(message.c_str())+1);
close(clientFd);
exit(0);
}
else
close(clientFd);

}

return 0;
}

My question is:
How do i make the server to fork a process to handle client query when they connect.

I don’t want it keep forking for no reasons.
Thanks for all help, this my first C coding to learn more about programming.

My client and server communicate through localhost, sockaddr_un and not internet.

Answer 1

What you should have for your loop is:

while (1) {
    clientFd = accept(serverFd, clientSockAddressPnt, (socklen_t*)&clientlen);
    if (clientFd >= 0) {
        if(fork() == 0) {
            message="Successfully connected to the server";
            write(clientFd,message.c_str(),strlen(message.c_str())+1);
            close(clientFd);
            exit(0);
        }
        else
            close(clientFd);
    }
}

That way, you only ever fork when accept returns a nonnegative value (which means it completed successfully.