#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netdb.h>
#include <netinet/in.h>

#define PORT 79

void
die(char *msg)
{
    fprintf(stderr, "%s\n", msg);
    exit(1);
}

void
read_server_response(int sockfd)
{
    char c;
    while (read(sockfd, &c, 1)) {
        putchar(c);
    }
}

void
finger_serverinfo(int sockfd)
{
    write(sockfd, "\r\n", 2);

    read_server_response(sockfd);
}

void
finger_user(int sockfd, char *username)
{
    write(sockfd, username, strlen(username));
    write(sockfd, "\r\n", 2);

    read_server_response(sockfd);
}

int
main(int argc, char *argv[])
{
    /* argument handling */
    if (argc < 2 || argc > 3)
        die("usage: finger [user] server");

    char *servername, *user = NULL;
    if (argc == 2) {
        servername = argv[1];
    }
    else {
        servername = argv[2];
        user = argv[1];
    }

    /* setting up sockets and stuff */
    struct sockaddr_in servaddr;

    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1)
        die("Couldn't create socket.");

    struct hostent *he = gethostbyname(servername);
    if (he == NULL)
        die("Couldn't get host.");

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr = *((struct in_addr *) he->h_addr_list[0]);
    servaddr.sin_port = htons(PORT);

    if (connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) != 0)
        die("Couldn't connect to server.");

    if (user)
        finger_user(sockfd, user);
    else
        finger_serverinfo(sockfd);

    close(sockfd);
}