#include <many-header-files.h>

int main(int argc, char *argv[])
{
//  LOCATE INFORMATION ABOUT THE REQUIRED SERVICE (PROTOCOL AND PORT)
    struct servent     *sp = getservbyname("login", "tcp");

    if(sp == NULL) {
        fprintf(stderr,"rlogin: tcp/login: unknown service\n");
        exit(1);
    }

//  LOCATE INFORMATION ABOUT THE REQUIRED HOST (ITS IP ADDRESS)
    struct hostent     *hp = gethostbyname(argv[1]);

    if(hp == NULL) {
        fprintf(stderr,"rlogin: %s: unknown host\n",argv[1]);
        exit(2);
    }

//  ASK OUR OS KERNEL TO ALLOCATE RESOURCES FOR A SOCKET
    int  sd  = socket(AF_INET, SOCK_STREAM, 0);
    if(sd < 0) {
        perror("rlogin: socket");
        exit(3);
    }

//  INITIALIZE FILEDS OF A STRUCTURE USED TO CONTACT SERVER
    struct sockaddr_in server;

    memset(&server, 0, sizeof(server));
    memcpy(&server.sin_addr, hp->h_addr, hp->h_length);
    server.sin_family  = hp->h_addrtype;
    server.sin_port    = sp->s_port;

//  CONNECT TO SERVER
    if(connect(sd, &server, sizeof(server)) < 0) {
        perror("rlogin: connect");
        exit(4);
    }
    
    communicate_with_rlogin_server(sd);
    shutdown(sd, SHUT_RDWR);
    close(sd);
    exit(EXIT_SUCCESS);
}