#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <strings.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>



int happy = 0;

int valid_fn (unsigned char fn)
{
  switch (fn) {
  case 0x30:
  case 0x31:
  case 0x32:
  case 0x33:
  case 0x34:
  case 0x35:
  case 0x36:
  case 0x37:
  case 0x38:
  case 0x08:
  case 0x39:
  case 0x09:
  case 0x43:
  case 0x45:
  case 0x4E:
  case 0x4F:
  case 0x50:
  case 0x40:
  case 0x3F:
  case 0x23:
  case 0x26:
  case 0x41:
  case 0x58:
  case 0x4C:
  case 0x56:
  case 0x76:
  case 0x49:
    return 1;
  }

  return 0;
}

int ackable (unsigned char fn)
{
  switch (fn) {


  case 0x09:
  case 0x39:
  case 0x08:
  case 0x38:
  case 0x40:
  case 0x43:
  case 0x58:
    return 0;
  }

  return 1;
}


void ack (int fd)
{
  char buf[3];

  buf[0] = 0;
  buf[1] = 0x38;
  buf[2] = 0xff ^ buf[0] ^ buf[1];

  write (fd, buf, sizeof (buf));

}

int rx_pkt (int fd, unsigned char *pkt, unsigned len)
{
  unsigned char parity = 0xff;
  unsigned i;

  for (i = 0; i < len; ++i)
    parity ^= pkt[i];

  if (parity) return -1;

  happy++;

  for (i = 2; i < len - 1; ++i) {
    if ((pkt[i] > 31) && (pkt[i] < 127))
      putchar (pkt[i]);
    else
      printf ("\\x%02x", pkt[i]);
  }

  printf ("\n");

  if ((pkt[0] & 0x40) && ackable (pkt[1])) ack (fd);

  return 0;
}



int rx (int fd)
{
  static unsigned char pkt[67];
  static unsigned ptr;
  unsigned char byte;
  unsigned len;

  if (read (fd, &byte, 1) != 1) {
    ptr = 0;
    return -1;
  }

  pkt[ptr++] = byte;

  if (ptr > 2 && !valid_fn (pkt[1])) {
    ptr = 0;
    return 0;
  }

  len = pkt[0] & 0x3f;

  if (ptr == (len + 3)) {
    ptr = 0;
    return rx_pkt (fd, pkt, len + 3);
  }

  return 0;
}



int transact (int fd, int ack, unsigned char fn, void *data, unsigned len, int timeout)
{
  struct timeval tv = {0};
  int rc;
  fd_set rfds;
  unsigned char buf[67], parity;
  unsigned i;

  happy = 0;

  tv.tv_sec = timeout;

  buf[0] = len;

  if (ack) buf[0] |= 0x40;

  buf[1] = fn;

  memcpy (&buf[2], data, len);

  parity = 0xff;

  for (i = 0; i < (len + 2); ++i)
    parity ^= buf[i];

  buf[i] = parity;
  i++;


  write (fd, buf, i);

  fwrite (data, 1, len, stdout);

  printf (" => ");
  fflush (stdout);



  while (!happy) {

    FD_ZERO (&rfds);

    FD_SET (fd, &rfds);

    rc = select (fd + 1, &rfds, NULL, NULL, &tv);

    if (!rc) break;

    rx (fd);

  }

  return happy;
}



int main (int argc, char *argv[])
{
  struct sockaddr_in sin;
  int fd;

  unsigned char buf[128];

  fd = socket (PF_INET, SOCK_STREAM, 0);

  sin.sin_family = AF_INET;
  sin.sin_port = htons (10005);
  inet_aton ("10.32.52.66", &sin.sin_addr);

  connect (fd, (struct sockaddr *)&sin, sizeof (sin));



  transact (fd, 1, 0x3f, "543210", 6, 4);
  transact (fd, 1, 0x43, "SA", 2, 4);

  transact (fd, 1, 0x3f, "543210", 6, 4);
  transact (fd, 1, 0x43, "SA91", 4, 4);

  transact (fd, 1, 0x3f, "543210", 6, 4);
  transact (fd, 1, 0x43, "SA92", 4, 4);

  if (argc == 2) {
    sprintf (buf, "SA1*%s", argv[1]);
    transact (fd, 1, 0x3f, "543210", 6, 4);
    transact (fd, 1, 0x43, buf, strlen (buf), 4);
  }

  close (fd);
}