#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <errno.h>
#include <signal.h>

#define MAXLINE 10240
#define defaultURL "/"


struct sockaddr_in server_addr; /* server's address */

char *programName;

void usage()
{
  fprintf(stderr, "usage: %s host URL\n", programName);
  exit(-1);
}


main(argc, argv)
int argc;
char **argv;
{

  struct hostent *hostentry;

  char *url;
  char recvline[MAXLINE + 1];
  char GetCMD[MAXLINE + 1];

  int n;
  int client_socket_fd;			/* Socket to client, server */
  int sz;
  int optval;			/* the socket option value */
  int optlen;			/* length of the option value */

  long inaddr;

  programName = argv[0];

  if ((argc < 2) || (argc > 3))	/* Check the arguments first. */
    usage();

  /* initialize the server address structure */
  memset( (char*)&server_addr, 0, sizeof(server_addr));

  server_addr.sin_family=PF_INET;
  server_addr.sin_port=htons(80); /* 80 is the TCP port number for HTTP */

/* Assume if the first character is a digit that it is an decimal dot
   notation IP address */

  if (isdigit(argv[1][0]) > 0) {
    server_addr.sin_addr.s_addr = inet_addr(argv[1]);
  }
  else {
    hostentry=gethostbyname(argv[1]);
    if ( hostentry == NULL)
      {
	fprintf(stderr, "invalid host name for server: %s", argv[1]);
	exit(1);
      }

    /* Note that below we use only the first address, if the
       host has several possible address; the better thing to do
       would be to try each of the addresses in the list */

    server_addr.sin_addr.s_addr = inet_addr(inet_ntoa(hostentry->h_addr_list[0]));
    };

    if (server_addr.sin_addr.s_addr == -1)
      {
	fprintf(stderr, "could not get an address for: %s", argv[1]);
	exit(1);
      }

  client_socket_fd = socket(PF_INET, SOCK_STREAM, 0);  /* create a socket */

  if (client_socket_fd < 0)
    {
      perror("Unable to open socket");
      exit(1);
    };

  /* the code below allows you to very the sizeof your received buffer */

  optval = 512;			/* to be set as size of receive buffer */
				/* note that it must be passed via a char* */
  optlen = 4;			/* size of the option in bytes */

  if (setsockopt(client_socket_fd, SOL_SOCKET, SO_RCVBUF, (char*)&optval, optlen) == -1) {
	  fprintf( stderr, "%s error in setting receive buffer size:", argv[0]);
	  perror( "setsockopt");
 	  close(client_socket_fd);
	  exit(1);
     }

  if (connect(client_socket_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0)
    {
      perror("Unable to connect with socket");
      close(client_socket_fd);
      exit(1);
    };


  if (argc > 2)
    sprintf(GetCMD, "GET %s HTTP/1.0\r\n\r\n", argv[2]);
  else {
    sprintf(GetCMD, "GET %s HTTP/1.0\r\n\r\n", defaultURL);
  };

  /* fprintf(stderr, "GetCMD: %s\n", GetCMD); */

  if (write(client_socket_fd, GetCMD, strlen(GetCMD)) < 0) {
      perror("socket write error");
  };

  while ( (n = read(client_socket_fd, recvline, MAXLINE)) > 0) {
    recvline[n] = 0;	/* null terminate */
    if (fputs(recvline, stdout) == EOF)
      perror("fputs error");
  }

  if (n < 0)
    perror("read error");

  close(client_socket_fd);	/* close the socket */

  exit(0);
}