TCP-IP CODES WRITTEN BY ME

THIS IS THE TCP-IP CODE THAT I HAVE WRITTEN FOR THE DOS MODE IN "C" LANGUAGE:

COPYRIGHT: GAIRIK BHATTACHARYA

THE FIRST PART:

/*
#      receives numbered UDP datagrams from a remote host.
#
#      Usage:
#          udp-recv source_adr [-p<port_number>][-t<timeout>]
#
#          <port_number> defaults to 9870.
#   Use source_adr of 255.255.255.255 to accept packets from anyone.
#
# Renaud Waldura # on Sep 18 16:51:24 1995
# converted from Perl to trumpet abi by Dan Kegel and Chris Thomas 6/7/1996
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <conio.h>
#include <ctype.h>

#include <tcpabi/tcpabi.h>
#include <tcpabi/tdprint.h>

#define TRUE (1)
#define FALSE (0)

#define BUFLEN 512
static char inbuf[BUFLEN];

int port = 9870;
int timeout_interval = 20; // anything less than 18 seems to be treated as 0

void print_usage( char *progname )
{
printf("     Usage: %s <ip_adr> [-p <port_number>][-t <timeout_interval>]\n", progname);
}

void get_stat(unsigned h)
{
int i;
unsigned size = 65535;

tcpabi_session_info_t __fAr *info;
i = tcpabi_udp_status(h, 0, &size, &info);
if (_tcpabi_errno != 0)
  printf("bad status! errno %d\n", _tcpabi_errno);
else
  printf("status: errno %d, return %d, size %d, ip_src %lx %d.%d.%d.%d port_loc %d, ip_dst %lx %d.%d.%d.%d port_rem %d, active %d\n",
   _tcpabi_errno, i, size,
   info->ip_src,
   ((unsigned char *)&info->ip_src)[0],
   ((unsigned char *)&info->ip_src)[1],
   ((unsigned char *)&info->ip_src)[2],
   ((unsigned char *)&info->ip_src)[3],
   info->port_loc,
   info->ip_dst,
   ((unsigned char *)&info->ip_dst)[0],
   ((unsigned char *)&info->ip_dst)[1],
   ((unsigned char *)&info->ip_dst)[2],
   ((unsigned char *)&info->ip_dst)[3],
   info->port_rem,
   info->active);
}

int receive_test(char *hostname)
{
unsigned int receive_handle;
unsigned long dst_ip;
unsigned dst_port;
unsigned src_port;

int n;
int err;

printf("resolving address for host %s\n", hostname);
if (isdigit(hostname[0])) {
  dst_ip = htonl(aton(hostname));
} else if ((dst_ip = resolve(hostname)) == 0L) {
  printf("receive_test: Can't resolve '%s' to IP address\n", hostname);
  return FALSE;
}

// open a handle to receive packets on specified port
dst_port = 0;
src_port = port;

receive_handle = tcpabi_udp_open(dst_ip, dst_port, src_port, UDP_OPEN_NORMAL, NULL);
if (receive_handle == NULL_HANDLE) {
  printf("error opening receive_handle!\n");
  return FALSE;
}
printf("ip %d.%d.%d.%d, dst_port %d, src_port %d, handle %d, timeout %d\n",
  ((unsigned char *)&dst_ip)[0],
  ((unsigned char *)&dst_ip)[1],
  ((unsigned char *)&dst_ip)[2],
  ((unsigned char *)&dst_ip)[3],
  dst_port, src_port, receive_handle, timeout_interval);

#if 0
// test behavior of info call. Does it apply to the head or the tail of
// the queue?
while (!kbhit()) {
  get_stat(receive_handle);
  sleep(1);
}
getch();
#endif
for (n = 1; !kbhit(); n++) {
  int i;
  i = tcpabi_udp_recv(receive_handle, inbuf, BUFLEN, timeout_interval, UDP_SEND_NORMAL, NULL, NULL);
  if (i == -1) {
  } else {
   printf("test_udprecv: got %d bytes: '", i);
   fwrite(inbuf, sizeof(char), i, stdout);
   printf("'\n");
   get_stat(receive_handle);
  }
}

tcpabi_udp_close(receive_handle, UDP_CLOSE_NORMAL);
return TRUE;

}

#ifdef __386__
#include <dos.h>
#define DPMI_INT 0x31
/*-------------------------------------------------------------------------
Get a block of DOS memory.
Return flat pointer to it, or NULL on failure.
Also place segmented real mode pointer in *seg, *off, and protected mode
selector in *sel. (The selector is only needed to free the memory,
thanks to the flat memory model of DOS4G.)
-------------------------------------------------------------------------*/
void *my_dos_malloc(size_t len, short *seg, short *off, short *sel)
{
union REGS regs;

// Note: The DPMI service expects the number of paragraphs not bytes.
regs.w.ax = (short) 0x0100;
regs.w.bx = (len + 0xf) >> 4;
int386(DPMI_INT, &regs, &regs);
if (regs.w.cflag) {
  // Abort!   Out of DOS memory!
  return NULL;
}

// Result is in AX:DX (seg:sel)
*seg = regs.w.ax;
*off = 0;
*sel = regs.w.dx;
DPRINT(("allocated selector %x\n", regs.w.dx));
return (void *) (regs.w.ax << 4);
}

/*-------------------------------------------------------------------------
Free a block of DOS memory allocated with my_dos_alloc.
-------------------------------------------------------------------------*/
void my_dos_free(short sel)
{
union REGS regs;

// Note: The DPMI service expects the number of paragraphs not bytes.
regs.w.ax = (short) 0x0101;
regs.w.dx = sel;
int386(DPMI_INT, &regs, &regs);
if (regs.w.cflag) {
  DPRINT(("my_dos_free: Can't free DOS memory at selector %x, error %d!\n",
   sel, regs.w.ax));
}
}
#endif

void main( int argc, char *argv[] )
{
   int i;
   short selector;

   puts("udprecv test (for UDP ABI) -- Copyright (C) 1994, Michael S. Durkin");

   if((argc == 1) || (argv[1][0] == '-')) {
      print_usage( argv[0] );
      exit(1);
   }
   for (i = 2; i<argc; i++) {
    if (argv[i][0] == '-') {
     switch (argv[i][1]) {
     case 'p': port = atoi(argv[i]+2); break;
     case 't': timeout_interval = atoi(argv[i]+2); break;
     default:  print_usage(argv[0]); exit(1);
     }
    }
   }

#ifdef __386__
scratch_flat = my_dos_malloc(BUFLEN, &scratch_seg, &scratch_off, &selector);
if (!scratch_flat) {
  printf("couldn't allocate DOS memory!\n");
  exit(3);
}
#endif
   if( !tcpabi_installed() ) {
      printf("\n   UDP ABI not found\n");
      exit(2);
   }

   receive_test(argv[1]);
   exit(0);
}

THE SECOND PART OF THE TCP-IP CODE: