SimpleEventBuilder/event_builder.cxx

#include <arpa/inet.h>
#include <csignal>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <netinet/in.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

#include <sys/time.h>
#include <errno.h>

#include <queue>
#include <vector>


int makeSocket() {
    int sockfd;
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }
    return sockfd;
}

void bindSocketPort(int server_fd, int port) {
    struct sockaddr_in localAddr;
    localAddr.sin_family = AF_INET;
    localAddr.sin_addr.s_addr = INADDR_ANY;
    localAddr.sin_port = htons(port);

    if (bind(server_fd, (struct sockaddr *)&localAddr, sizeof(localAddr)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }
    printf("FD %d bound to port %d\n", server_fd, port);
}

void startListening(int server_fd) {
    if (listen(server_fd, 3) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }
    printf("FD %d listening to new connections\n", server_fd);
}

int acceptConnection(int server_fd) {
    int client_fd;
    struct sockaddr_in remoteAddr;

    size_t addrlen = sizeof(remoteAddr);
    if ((client_fd = accept(server_fd, (struct sockaddr *)&remoteAddr, (socklen_t *)&addrlen)) < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    }
    printf("Connection from host %s, port %d, FD %d\n", inet_ntoa(remoteAddr.sin_addr), ntohs(remoteAddr.sin_port), client_fd);
    return client_fd;
}

void term_handler(int signal) {
    printf("Terminated, received SIGNAL %d", signal);
    exit(EXIT_SUCCESS);
}

/*
int main(int argc, char const *argv[]) {
    signal(SIGTERM, term_handler);

    if (argc != 2) {
        printf("Usage: %s portNumber \n", argv[0]);
        exit(EXIT_FAILURE);
    }
    int port = atoi(argv[1]);
    printf("Start socket port %d\n", port);

    int server_fd = makeSocket();
    bindSocketPort(server_fd, port);
    startListening(server_fd);
    int client_fd = acceptConnection(server_fd);

    while (true) {
        uint32_t word;
        ssize_t bytes = read(client_fd, &word, 4);
        if (bytes != 4) {
            perror("Receive failed");
            exit(EXIT_FAILURE);
        }
        printf("[RICEVUTO]\t0x%x\n", word);
    }


    return 0;
}*/

#define TRUE   1 
#define FALSE  0 

int main(int argc, char const *argv[]) {
    signal(SIGTERM, term_handler);

    if (argc != 2) {
        printf("Usage: %s portNumber \n", argv[0]);
        exit(EXIT_FAILURE);
    }
    int port = atoi(argv[1]);
    printf("Start socket port %d\n", port);

    int opt = TRUE;  
    int master_socket , addrlen , new_socket , client_socket[30] , 
          max_clients = 30 , activity, i , valread , sd;  
    int max_sd;

    //set of socket descriptors 
    fd_set readfds;  

    //initialise all client_socket[] to 0 so not checked 
    for (i = 0; i < max_clients; i++)  
    {  
        client_socket[i] = 0;  
    }  

    master_socket = makeSocket();

    //set master socket to allow multiple connections , 
    //this is just a good habit, it will work without this 
    if( setsockopt(master_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, 
          sizeof(opt)) < 0 )  
    {  
        perror("setsockopt");  
        exit(EXIT_FAILURE);  
    }

    bindSocketPort(master_socket, port);
    startListening(master_socket);

    while (true) {
        //clear the socket set 
        FD_ZERO(&readfds);  
     
        //add master socket to set 
        FD_SET(master_socket, &readfds);  
        max_sd = master_socket;

        //add child sockets to set 
        for ( i = 0 ; i < max_clients ; i++)  
        {  
            //socket descriptor 
            sd = client_socket[i];  
                 
            //if valid socket descriptor then add to read list 
            if(sd > 0)  
                FD_SET( sd , &readfds);  
                 
            //highest file descriptor number, need it for the select function 
            if(sd > max_sd)  
                max_sd = sd;  
        }

        //wait for an activity on one of the sockets , timeout is NULL , 
        //so wait indefinitely 
        activity = select( max_sd + 1 , &readfds , NULL , NULL , NULL);

        if ((activity < 0) && (errno!=EINTR))  
        {  
            printf("select error");  
        } 

        //If something happened on the master socket , 
        //then its an incoming connection 
        if (FD_ISSET(master_socket, &readfds))  
        {  
            new_socket = acceptConnection(master_socket);
                 
            //add new socket to array of sockets 
            for (i = 0; i < max_clients; i++)  
            {  
                //if position is empty 
                if( client_socket[i] == 0 )  
                {  
                    client_socket[i] = new_socket;  
                    printf("Adding to list of sockets as %d\n" , i);  
                         
                    break;  
                }  
            }  
        }

        //else its some IO operation on some other socket
        for (i = 0; i < max_clients; i++)
        {
            sd = client_socket[i];  
            
            if (FD_ISSET( sd , &readfds))
            {
                //Check if it was for closing , and also read the 
                //incoming message
                uint32_t word;
                if ((valread = recv( sd , &word, 4, 0)) == 0)  
                {
                    struct sockaddr_in address;
                    int addrlen;
                    //Somebody disconnected , get his details and print 
                    getpeername(sd , (struct sockaddr*)&address , \
                        (socklen_t*)&addrlen);  
                    printf("Host disconnected , ip %s , port %d \n" , 
                          inet_ntoa(address.sin_addr) , ntohs(address.sin_port)); 

                    printf("Disconnected fd %d", sd);
                    
                    //Close the socket and mark as 0 in list for reuse
                    close( sd );
                    client_socket[i] = 0;
                }
                
                //Echo back the message that came in 
                else 
                {  
                    printf("[RICEVUTO]\t0x%x FROM %d\n", word, sd);
                }  
            }  
        }


    }

    /*

    int client_fd = acceptConnection(server_fd);

    while (true) {
        uint32_t word;
        ssize_t bytes = read(client_fd, &word, 4);
        if (bytes != 4) {
            perror("Receive failed");
            exit(EXIT_FAILURE);
        }
        printf("[RICEVUTO]\t0x%x\n", word);
    }*/


    return 0;
}