client.cpp

#include "utils.h"

int main(int argc, char **argv) {
    
    DIE(argc != 4, "Client must have 3 arguments: CLIENT_ID, SERVER_IP and SERVER_PORT!");
    
    char *id = argv[1];
    char *server_ip = argv[2];
    char *server_port = argv[3];
    int ret;
    int flag = 1;
    bool is_running = true;

    setvbuf(stdout, NULL, _IONBF, BUFSIZ);

    DIE(strlen(id) > 10, "ID must be 10 characters long!\n");
    char buffer[sizeof(tcp_message_t) + 1];

    int fd_socket = socket(AF_INET, SOCK_STREAM, 0);
    DIE(fd_socket < 0, "Failed to open the socket.\n");

    setsockopt(fd_socket, IPPROTO_TCP, TCP_NODELAY, (char *)&flag, sizeof(int));
    
    sockaddr_in sock_addr;
    sock_addr.sin_family = AF_INET;
    sock_addr.sin_port = htons(atoi(server_port));
    ret = inet_aton(server_ip, &sock_addr.sin_addr);
    DIE(ret == 0, "Server IP is not correct.\n");

    ret = connect(fd_socket, (sockaddr *) &sock_addr, sizeof(sock_addr));
    DIE(ret < 0, "Connection has failed!\n");

    ret = send(fd_socket, id, strlen(id) + 1, 0);
    DIE(ret < 0, "send() failed\n");

    ret = recv(fd_socket, buffer, 1, 0);
    DIE(ret < 0, "connection recv() failed!\n");

    if (buffer[0] == 'f') {
        is_running = false;
    }

    pollfd stdin_pollfd;
    stdin_pollfd.fd = STDIN_FILENO;
    stdin_pollfd.events = POLLIN;

    pollfd socket_pollfd;
    socket_pollfd.fd = fd_socket;
    socket_pollfd.events = POLLIN | POLLOUT;

    std::vector<pollfd> pollfds;
    pollfds.push_back(stdin_pollfd);
    pollfds.push_back(socket_pollfd);

    while (is_running) {

        ret = poll(pollfds.data(), pollfds.size(), -1);
        DIE(ret < 0, "poll() failed\n");

        memset(buffer, 0, sizeof(buffer));

        for (unsigned long i = 0; i < pollfds.size(); i++) {
            
            if (pollfds[i].fd == STDIN_FILENO && pollfds[i].revents & POLLIN) {
                
                fgets(buffer, sizeof(buffer), stdin);
                
                if (strcmp(buffer, "exit\n") == 0) {
                    is_running = false;
                    break;
                }
                else if (strncmp(buffer, "subscribe ", 10) == 0) {
                    tcp_client_request request;
                    request.subscribe = true;
                    
                    char *topic = strchr(buffer + 10, '\n');

                    if (topic) {
                        *topic = '\0';
                    }

                    if (strlen(buffer + 10) > 51) {
                        fprintf(stderr, "Topic must have less than 50 characters\n");
                    } else {
                        strcpy(request.topic, buffer + 10);
                        ret = send(fd_socket, &request, sizeof(request), 0);
                        DIE(ret < 0, "subscribe has failed");
                        printf("Subscribed to topic %s\n", request.topic);
                    }
                }
                else if (strncmp(buffer, "unsubscribe ", 12) == 0) {
                    tcp_client_request request;
                    request.subscribe = false;

                    char *topic = strchr(buffer + 12, '\n');

                    if (topic) {
                        *topic = '\0';
                    }
                    
                    if (strlen(buffer + 12) > 51) {
                        fprintf(stderr, "Topic must have less than 50 characters\n");
                    } else {
                        strcpy(request.topic, buffer + 12);
                        ret = send(fd_socket, &request, sizeof(request), 0);
                        DIE(ret < 0, "subscribe has failed");
                        printf("Unsubscribed from topic %s\n", request.topic);
                    }
                }
            }
            else if (pollfds[i].fd == fd_socket && pollfds[i].revents & POLLIN) {
                
                ret = recv(fd_socket, buffer, sizeof(tcp_message_t), 0);
                DIE(ret < 0, "tcp recv() failed\n");

                if (ret == 0) {
                    is_running = false;
                    break;
                }

                tcp_message_t *result = (tcp_message_t *)buffer;

                printf("%s:%hu - %s - %s - %s\n", result->ip_addr, result->port, 
                    result->topic, result->type, result->payload);
            }
        }
    }
    close(fd_socket);
    return 0;
}