/**
 * \addtogroup uip
 * @{
 */

/**
 * \file
 * The uIP TCP/IP stack code.
 * \author Adam Dunkels <adam@dunkels.com>
 */

/*
 * Copyright (c) 2001-2003, Adam Dunkels.
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 * 3. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior
 *    written permission.  
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  
 *
 * This file is part of the uIP TCP/IP stack.
 *
 * $Id: uip.c,v 1.62.2.10 2003/10/07 13:23:01 adam Exp $
 *
 */

/*
This is a small implementation of the IP and TCP protocols (as well as
some basic ICMP stuff). The implementation couples the IP, TCP and the
application layers very tightly. To keep the size of the compiled code
down, this code also features heavy usage of the goto statement.

The principle is that we have a small buffer, called the uip_buf, in
which the device driver puts an incoming packet. The TCP/IP stack
parses the headers in the packet, and calls upon the application. If
the remote host has sent data to the application, this data is present
in the uip_buf and the application read the data from there. It is up
to the application to put this data into a byte stream if needed. The
application will not be fed with data that is out of sequence.

If the application whishes to send data to the peer, it should put its
data into the uip_buf, 40 bytes from the start of the buffer. The
TCP/IP stack will calculate the checksums, and fill in the necessary
header fields and finally send the packet back to the peer.
*/

#include "uip.h"
#include "uipopt.h"
#include "uip_arch.h"

/*-----------------------------------------------------------------------------------*/
/* Variable definitions. */


/* The IP address of this host. If it is defined to be fixed (by setting UIP_FIXEDADDR to 1 in uipopt.h), the address is set here. Otherwise, the address */
#if UIP_FIXEDADDR > 0
const u16_t uip_hostaddr[2] =
  {HTONS((UIP_IPADDR0 << 8) | UIP_IPADDR1),
   HTONS((UIP_IPADDR2 << 8) | UIP_IPADDR3)};
const u16_t uip_arp_draddr[2] =
  {HTONS((UIP_DRIPADDR0 << 8) | UIP_DRIPADDR1),
   HTONS((UIP_DRIPADDR2 << 8) | UIP_DRIPADDR3)};
const u16_t uip_arp_netmask[2] =
  {HTONS((UIP_NETMASK0 << 8) | UIP_NETMASK1),
   HTONS((UIP_NETMASK2 << 8) | UIP_NETMASK3)};
#else
u16_t uip_hostaddr[2];       
u16_t uip_arp_draddr[2], uip_arp_netmask[2];
#endif /* UIP_FIXEDADDR */

u8_t uip_buf[UIP_BUFSIZE+2];   /* The packet buffer that contains
				incoming packets. */
volatile u8_t *uip_appdata;  /* The uip_appdata pointer points to
				application data. */
volatile u8_t *uip_sappdata;  /* The uip_appdata pointer points to the
				 application data which is to be sent. */
#if UIP_URGDATA > 0
volatile u8_t *uip_urgdata;  /* The uip_urgdata pointer points to
				urgent data (out-of-band data), if
				present. */
volatile u8_t uip_urglen, uip_surglen;
#endif /* UIP_URGDATA > 0 */

volatile u16_t uip_len, uip_slen;
                             /* The uip_len is either 8 or 16 bits,
				depending on the maximum packet
				size. */

volatile u8_t uip_flags;     /* The uip_flags variable is used for
				communication between the TCP/IP stack
				and the application program. */
struct uip_conn *uip_conn;   /* uip_conn always points to the current
				connection. */

struct uip_conn uip_conns[UIP_CONNS];
                             /* The uip_conns array holds all TCP
				connections. */
u16_t uip_listenports[UIP_LISTENPORTS];
                             /* The uip_listenports list all currently
				listning ports. */
#if UIP_UDP
struct uip_udp_conn *uip_udp_conn;
struct uip_udp_conn uip_udp_conns[UIP_UDP_CONNS];
#endif /* UIP_UDP */


static u16_t ipid;           /* Ths ipid variable is an increasing
				number that is used for the IP ID
				field. */

static u8_t iss[4];          /* The iss variable is used for the TCP
				initial sequence number. */

#if UIP_ACTIVE_OPEN
static u16_t lastport;       /* Keeps track of the last port used for
				a new connection. */
#endif /* UIP_ACTIVE_OPEN */

/* Temporary variables. */
volatile u8_t uip_acc32[4];
static u8_t c, opt;
static u16_t tmp16;

/* Structures and definitions. */
#define TCP_FIN 0x01
#define TCP_SYN 0x02
#define TCP_RST 0x04
#define TCP_PSH 0x08
#define TCP_ACK 0x10
#define TCP_URG 0x20
#define TCP_CTL 0x3f

#define ICMP_ECHO_REPLY 0
#define ICMP_ECHO       8     

/* Macros. */
#define BUF ((uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
#define FBUF ((uip_tcpip_hdr *)&uip_reassbuf[0])
#define ICMPBUF ((uip_icmpip_hdr *)&uip_buf[UIP_LLH_LEN])
#define UDPBUF ((uip_udpip_hdr *)&uip_buf[UIP_LLH_LEN])

#if UIP_STATISTICS == 1
struct uip_stats uip_stat;
#define UIP_STAT(s) s
#else
#define UIP_STAT(s)
#endif /* UIP_STATISTICS == 1 */

#if UIP_LOGGING == 1
#include <stdio.h>
void uip_log(char *msg);
#define UIP_LOG(m) uip_log(m)
#else
#define UIP_LOG(m)
#endif /* UIP_LOGGING == 1 */

/*-----------------------------------------------------------------------------------*/
void
uip_init(void)
{
  for(c = 0; c < UIP_LISTENPORTS; ++c) {
    uip_listenports[c] = 0;
  }
  for(c = 0; c < UIP_CONNS; ++c) {
    uip_conns[c].tcpstateflags = CLOSED;
  }
#if UIP_ACTIVE_OPEN
  lastport = 1024;
#endif /* UIP_ACTIVE_OPEN */

#if UIP_UDP
  for(c = 0; c < UIP_UDP_CONNS; ++c) {
    uip_udp_conns[c].lport = 0;
  }
#endif /* UIP_UDP */
  

  /* IPv4 initialization. */
#if UIP_FIXEDADDR == 0
  uip_hostaddr[0] = uip_hostaddr[1] = 0;
#endif /* UIP_FIXEDADDR */

}
/*-----------------------------------------------------------------------------------*/
#if UIP_ACTIVE_OPEN
struct uip_conn *
uip_connect(u16_t *ripaddr, u16_t rport)
{
  register struct uip_conn *conn, *cconn;
  
  /* Find an unused local port. */
 again:
  ++lastport;

  if(lastport >= 32000) {
    lastport = 4096;
  }

  /* Check if this port is already in use, and if so try to find
     another one. */
  for(c = 0; c < UIP_CONNS; ++c) {
    conn = &uip_conns[c];
    if(conn->tcpstateflags != CLOSED &&
       conn->lport == htons(lastport)) {
      goto again;
    }
  }


  conn = 0;
  for(c = 0; c < UIP_CONNS; ++c) {
    cconn = &uip_conns[c]; 
    if(cconn->tcpstateflags == CLOSED) {
      conn = cconn;
      break;
    }
    if(cconn->tcpstateflags == TIME_WAIT) {
      if(conn == 0 ||
	 cconn->timer > uip_conn->timer) {
	conn = cconn;
      }
    }
  }

  if(conn == 0) {
    return 0;
  }
  
  conn->tcpstateflags = SYN_SENT;

  conn->snd_nxt[0] = iss[0];
  conn->snd_nxt[1] = iss[1];
  conn->snd_nxt[2] = iss[2];
  conn->snd_nxt[3] = iss[3];

  conn->initialmss = conn->mss = UIP_TCP_MSS;
  
  conn->len = 1;   /* TCP length of the SYN is one. */
  conn->nrtx = 0;
  conn->timer = 1; /* Send the SYN next time around. */
  conn->rto = UIP_RTO;
  conn->sa = 0;
  conn->sv = 16;
  conn->lport = htons(lastport);
  conn->rport = rport;
  conn->ripaddr[0] = ripaddr[0];
  conn->ripaddr[1] = ripaddr[1];
  
  return conn;
}
#endif /* UIP_ACTIVE_OPEN */
/*-----------------------------------------------------------------------------------*/
#if UIP_UDP
struct uip_udp_conn *
uip_udp_new(u16_t *ripaddr, u16_t rport)
{
  register struct uip_udp_conn *conn;
  
  /* Find an unused local port. */
 again:
  ++lastport;

  if(lastport >= 32000) {
    lastport = 4096;
  }
  
  for(c = 0; c < UIP_UDP_CONNS; ++c) {
    if(uip_udp_conns[c].lport == lastport) {
      goto again;
    }
  }


  conn = 0;
  for(c = 0; c < UIP_UDP_CONNS; ++c) {
    if(uip_udp_conns[c].lport == 0) {
      conn = &uip_udp_conns[c]; 
      break;
    }
  }

  if(conn == 0) {
    return 0;
  }
  
  conn->lport = HTONS(lastport);
  conn->rport = HTONS(rport);
  conn->ripaddr[0] = ripaddr[0];
  conn->ripaddr[1] = ripaddr[1];
  
  return conn;
}
#endif /* UIP_UDP */
/*-----------------------------------------------------------------------------------*/
void
uip_unlisten(u16_t port)
{
  for(c = 0; c < UIP_LISTENPORTS; ++c) {
    if(uip_listenports[c] == port) {
      uip_listenports[c] = 0;
      return;
    }
  }
}
/*-----------------------------------------------------------------------------------*/
void
uip_listen(u16_t port)
{
  for(c = 0; c < UIP_LISTENPORTS; ++c) {
    if(uip_listenports[c] == 0) {
      uip_listenports[c] = port;
      return;
    }
  }
}
/*-----------------------------------------------------------------------------------*/
/* XXX: IP fragment reassembly: not well-tested. */

#if UIP_REASSEMBLY
#define UIP_REASS_BUFSIZE (UIP_BUFSIZE - UIP_LLH_LEN)
static u8_t uip_reassbuf[UIP_REASS_BUFSIZE];
static u8_t uip_reassbitmap[UIP_REASS_BUFSIZE / (8 * 8)];
static const u8_t bitmap_bits[8] = {0xff, 0x7f, 0x3f, 0x1f,
				    0x0f, 0x07, 0x03, 0x01};
static u16_t uip_reasslen;
static u8_t uip_reassflags;
#define UIP_REASS_FLAG_LASTFRAG 0x01
static u8_t uip_reasstmr;

#define IP_HLEN 20
#define IP_MF   0x20

static u8_t
uip_reass(void)
{
  u16_t offset, len;
  u16_t i;

  /* If ip_reasstmr is zero, no packet is present in the buffer, so we
     write the IP header of the fragment into the reassembly
     buffer. The timer is updated with the maximum age. */
  if(uip_reasstmr == 0) {
    memcpy(uip_reassbuf, &BUF->vhl, IP_HLEN);
    uip_reasstmr = UIP_REASS_MAXAGE;
    uip_reassflags = 0;
    /* Clear the bitmap. */
    memset(uip_reassbitmap, sizeof(uip_reassbitmap), 0);
  }

  /* Check if the incoming fragment matches the one currently present
     in the reasembly buffer. If so, we proceed with copying the
     fragment into the buffer. */
  if(BUF->srcipaddr[0] == FBUF->srcipaddr[0] &&
     BUF->srcipaddr[1] == FBUF->srcipaddr[1] &&
     BUF->destipaddr[0] == FBUF->destipaddr[0] &&
     BUF->destipaddr[1] == FBUF->destipaddr[1] &&
     BUF->ipid[0] == FBUF->ipid[0] &&
     BUF->ipid[1] == FBUF->ipid[1]) {