e/* tcp_connect.c 
Connects to [char *hostname] on port [int port] and returns
a socket descriptor. */

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>

int tcp_connect(char *hostname, int port){
  int sockfd;
  struct sockaddr_in target;
  struct hostent *h;

  if((h = (struct hostent *) gethostbyname(hostname)) == 0){
       perror("gethostbyname()");
       return -1;
  }

  target.sin_family   = AF_INET;
  target.sin_port     = htons(port);
  target.sin_addr     = *((struct in_addr *)h->h_addr);

  if((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1){
    perror("socket");
    return -1;
  }

  if(connect(sockfd, (struct sockaddr *)&target, sizeof(struct sockaddr)) == -1){
    perror("connect");
    return -1;
  }

  return sockfd;
}


/*
A Simple Programming Exercise
Your goal is to connect to port 5842 on vortex.labs.pulltheplug.org and read in 4 unsigned integers. Add these integers together and send back the results to get a username and password for level 1. Note that vortex is on an x86 machine (meaning, a little endian architecture). 
*/
#include <stdio.h>
#include <stdlib.h>

#define BUFSIZE 256

int main(int argc, char **argv){
  int sockfd, i, recv_n, sent_n;
  unsigned int ui[4] = {0,0,0,0};
  unsigned long sum = 0;
  char answer[BUFSIZE];
  
  if((sockfd = tcp_connect("vortex.labs.pulltheplug.org", 5842)) == -1){
    exit(-1);
  }
  
  for(i = 0; i < 4; i++){
    if((recv_n = recv(sockfd, ui[i], sizeof(unsigned int), 0)) == -1){
      fprintf(stderr, "Error in receiving unsigned ints.\n");
      exit(-1);
    }
  }

  
  for(i = 0; i < 4; i++){
    sum += ui[i];
    fprintf(stdout, "Adding %u to sum: %u\n", ui[i], sum);
  }
  
  if((sent_n = send(sockfd, sum, sizeof(unsigned long), 0)) == -1){
    perror("send");
    exit(-1);
  }
  
  if((recv_n = recv(sockfd, answer, BUFSIZE, 0)) == -1){
    perror("recv");
    exit(-1);
  }
  
  fprintf(stdout, "%s\n", answer);
}