path: root/03_exercise/cli/client.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define PORT 9000
#define HOST "127.0.0.1"

#define BUF_SIZE 2048

int cfd;

/* Signal Handler for SIGINT */
void sigintHandler(int sig_num) {
    errno = 0;
    if (fcntl(cfd, F_GETFD) != -1 || errno != EBADF) {
        write(cfd, "exit\n", 6);
        close(cfd);
    }
    printf("Terminating client\n");
    fflush(stdout);
    exit(-1);
}

static inline void die(const char *msg) {
    perror(msg);
    exit(-1);
}

int main() {
    struct sockaddr_in addr = {
            .sin_family = AF_INET,
            .sin_port = htons(PORT),
            .sin_addr.s_addr = inet_addr(HOST)
    };
    char               buf[BUF_SIZE];

    if ((cfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
        die("Could not open socket");

    if (connect(cfd, (struct sockaddr *) &addr, sizeof(addr)) < 0)
        die("Could not connect to socket");

    char      *line = NULL;
    size_t    cap   = 0;
    __ssize_t length;

    if (read(cfd, buf, BUF_SIZE) < 0)
        die("Could not receive message");

    printf("%s\n$> ", buf);
    memset(buf, 0, BUF_SIZE);

    while (1) {
        //printf("[C] awaiting command\n");
        if ((length = getline(&line, &cap, stdin)) < 0) {
            fprintf(stderr, "Failed to read from STDIN");
            fflush(stderr);
            exit(-1);
        }

        if (strspn(line, " \n\t") == strlen(line)) {
            // skip empty lines - empty being just spaces or tabs
            continue;
        }

        strncpy(buf, line, strlen(line) + 1);

        //printf("[C] pre send: \"%s\"\n", buf);

        if (write(cfd, buf, strlen(line)) < 0)
            die("Could not send message");

        if (strcmp(line, "exit\n") == 0) {
            free(line);
            line = NULL;
            break;
        }

        if (read(cfd, buf, BUF_SIZE) < 0)
            die("Could not receive message");

        printf("%s$> ", buf);
        memset(buf, 0, BUF_SIZE);
        free(line);
        line = NULL;
    }

    close(cfd);
    return 0;
}