// https://systemprogrammingatntu.github.io/mp2/unix_socket.html

#define SOCKET_NAME "/tmp/resol.sock"
#define BUFFER_SIZE 12

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>

int main(int argc, char *argv[]) {
    struct sockaddr_un addr;
    int i;
    int ret;
    int data_socket;
    char buffer[BUFFER_SIZE];

    /* Create local socket. */
    data_socket = socket(AF_UNIX, SOCK_STREAM, 0);
    if (data_socket == -1) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    /*
     * For portability clear the whole structure, since some
     * implementations have additional (nonstandard) fields in
     * the structure.
     */
    memset(&addr, 0, sizeof(struct sockaddr_un));

    /* Connect socket to socket address */
    addr.sun_family = AF_UNIX;
    strncpy(addr.sun_path, SOCKET_NAME, sizeof(addr.sun_path) - 1);

    ret = connect (data_socket, (const struct sockaddr *) &addr,
                   sizeof(struct sockaddr_un));
    if (ret == -1) {
        fprintf(stderr, "The server is down.\n");
        exit(EXIT_FAILURE);
    }

    /* Send arguments. */
    for (i = 1; i < argc; ++i) {
        ret = write(data_socket, argv[i], strlen(argv[i]) + 1);
        if (ret == -1) {
            perror("write");
            break;
        }
    }

    /* Request result. */
    strcpy (buffer, "END");
    ret = write(data_socket, buffer, strlen(buffer) + 1);
    if (ret == -1) {
        perror("write");
        exit(EXIT_FAILURE);
    }

    /* Receive result. */
    ret = read(data_socket, buffer, BUFFER_SIZE);
    if (ret == -1) {
        perror("read");
        exit(EXIT_FAILURE);
    }

    /* Ensure buffer is 0-terminated. */
    buffer[BUFFER_SIZE - 1] = 0;

    printf("Result = %s\n", buffer);

    /* Close socket. */
    close(data_socket);

    exit(EXIT_SUCCESS);
}