Programming

int main(int argc, char **argv) {
    
    // Set Up
    int socket_fd, new_socket_fd, num; // file descriptors, and port number
    socklen_t client_length; // size of client address 
    struct sockaddr_in serv_addr, cli_addr;
    char buffer[MAXDATASIZE]; // input gets put here

    // Set Up Socket
    for(num=0;num<CONSIGNMENT;num++) client_names[num]=NULL;   // set all to Null 
    bzero(buffer,MAXDATASIZE); // Set all to zero
    socket_fd = socket(AF_INET, SOCK_STREAM, 0); // create a listening socket to the internet
    if (socket_fd < 0) error("ERROR opening socket"); // check the socket
    bzero((char *) &serv_addr, sizeof(serv_addr)); // sets all values in the serv_addr to 0
    serv_addr.sin_family = AF_INET; // set up the information for the server
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(PORT);
    if (bind(socket_fd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) error("ERROR on binding"); // check the bind
    listen(socket_fd,5); // sets it up for listening, max of 5 waiting connections while one is being handled             
    client_length = sizeof(cli_addr);
    
    while(1) {
        new_socket_fd = accept(socket_fd, (struct sockaddr *) &cli_addr, &client_length); // pause process until client connects
        if (new_socket_fd < 0) error("ERROR on accept"); // check new file descriptor

     // server and client talks....


        close(new_socket_fd); 
    }
    
    close(socket_fd); // close connections with client
    return(0); 
}

int maxproc=5; // Max # of simultaneous connections

{
        int newfd=accept(sock);

        // Handle children without blocking
        while(waitpid(-1, NULL, WNOHANG) >= 0)
        {
                maxproc++;
        }

        // If you've exceeded the maximum, actually wait
        if(maxproc <= 0) waitpid(-1, NULL, 0);

        switch(fork())
        {
        case -1: // Error
                perror("Couldn't fork");
                close(newfd);
                break;
        default: // Parent
                maxproc--;
                close(newfd);
                break;
        case 0: // child
                do_stuff();
                exit(0);
                break;        
        }
}

void send_message(int *client_socket_fd, char *message, int length) {
    if (write(*client_socket_fd, message, length) < 0) error("ERROR writing to socket");
}

void read_message(int *socket_fd, char *buffer, int display) {
    size_t bytes; 
    if((bytes = read(*socket_fd, buffer, MAXDATASIZE)) < 0) error("ERROR reading from socket");    
    if (display) write(1,buffer,bytes);    
}

#include "header.h"
int main(int argc, char **argv) {
    char buffer[MAXDATASIZE]; 
    bzero(buffer, sizeof(buffer)); 
    client *client_list=NULL; item *item_list=NULL;
    item_list = add_item("bike", "8", "70", "5", "False", item_list);
    int socket_fd, client_socket_fd; 
    socklen_t client_length; 
    struct sockaddr_in serv_addr, cli_addr;
    client_length = sizeof(cli_addr);
    bzero((char *) &serv_addr, sizeof(serv_addr)); 
    socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (socket_fd < 0) error("ERROR opening socket");
    serv_addr.sin_family = AF_INET; 
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(PORT);
    if (bind(socket_fd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) error("ERROR on binding"); 
    listen(socket_fd,5);          
    client_socket_fd = accept(socket_fd, (struct sockaddr *) &cli_addr, &client_length);
    if (client_socket_fd < 0) error("ERROR on accept"); 
    read_message(client_socket_fd, buffer, 0); 
    if (already_there(client_list, buffer)==0) {      
        client_list = add_client(buffer, client_list, client_socket_fd); 
        send_message(client_socket_fd, "Enter", 5); 
        write(1, buffer, str_len(buffer)); write(1, " connected!\n", 12); 
        read_message(client_socket_fd, buffer, 0); 
        send_items(item_list, client_socket_fd); 
    }
    else {                                       
        send_message(client_socket_fd, "Leave", 5); 
        write(1, "Rejected incoming client - ", 27); write(1, buffer, str_len(buffer)); write(1, "! (User with same name already connected)\n", 42); 
        read_message(client_socket_fd, buffer, 0); 
    }
    close(client_socket_fd); close(socket_fd); 
    return(0); 
}