Limiting Clients From Connecting - c

Question

Trying to limit the amount of client connections in my client-server c application. This is what I have, however it doesn't work. (Doesn't even recognise when max_connections is reached. How can I fix this?
int main(int argc, char *argv[])
{
//fill db
if (obtainDb() == false) {
printf("Database obtain error.\n");
exit(true);
}
//initialise variables
total_connections = 0;
/* generate the socket */
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(true);
}
/* generate the end point */
my_addr.sin_family = AF_INET; // host byte order
my_addr.sin_port = htons(MYPORT); // short, network byte order
my_addr.sin_addr.s_addr = INADDR_ANY; // auto-fill with my IP
/* bind the socket to the end point */
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) \
== -1) {
perror("bind");
exit(true);
}
/* start listnening */
if (listen(sockfd, BACKLOG) == -1) {
perror("listen");
exit(true);
}
printf("server starts listnening ...\n");
while(true){
sin_size = sizeof(struct sockaddr_in);
if (total_connections == max_connections) {
printf("Max Number of clients connected!\n");
while(total_connections == max_connections);
}
if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, \
&sin_size)) == -1) {
perror("accept");
continue;
}
total_connections++;
printf("server: got connection from %s\n", \
inet_ntoa(their_addr.sin_addr));
userInput();
while(waitpid(-1,NULL,WNOHANG)>0);
}
return false;
}
Thanks
Edit: UserInput():
void userInput(void) {
if (!fork()) { // this is the child process
while(true){
char buffer[MAXDATASIZE];
char res[MAXDATASIZE];
memset(buffer, '\0', MAXDATASIZE);
memset(res, '\0', sizeof(res));
if ((numbytes=recv(new_fd, buffer, sizeof(buffer), 0)) == -1) {
perror("recv");
exit(true);
}
if (numbytes == 0) {
printf("client left");
close(new_fd);
total_connections--;
exit(false);
}
buffer[numbytes] = '\0'; // add null terminator
printf("Request: %s\n",buffer);
search(buffer,res);
}
close(new_fd); // parent doesn't need this
exit(false);
}
close(new_fd);
}

Answer 1

When you fork all variables are copied to the new process. That means that the children have their own copy of total_connections.
Instead of using a variable, you should use wait to find out whether any children have exited.

Answer 2

Forking creates a new instance of your proces, which also means that each variable is copied to the new process. Your initial total_connections will actually never get increased beyond 1.
C fork dealing with global variable
A relatively simple option would be to use threads instead of processes for handling multiple clients simultaneously.