/*
 * Copyright (c) 2005, Swedish Institute of Computer Science.
 * 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. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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 Contiki operating system.
 *
 */

/**
 * \file
 *         Micro implementation of the AODV ad hoc routing protocol
 * \author
 *         Adam Dunkels <adam@sics.se>
 */

#include <stdio.h>
#include <stdarg.h>
#include <string.h>

#include "contiki.h"
#include "net/ipv4/uaodv-def.h"
#include "net/ipv4/uaodv-rt.h"

#define NDEBUG
#include "lib/assert.h"

#ifdef CC2420_RADIO
#include "cc2420.h"
#define RSSI_THRESHOLD -39	/* accept -39 ... xx */
#endif

/* This implementation never expires routes!!! */
#define MY_ROUTE_TIMEOUT 0x7fffffff /* Should be 0xffffffff! */
#define MY_NET_DIAMETER  20

PROCESS(uaodv_process, "uAODV");

static struct uip_udp_conn *bcastconn, *unicastconn;

/* Compare sequence numbers as per RFC 3561. */
#define SCMP32(a, b) ((int32_t)((a) - (b)))

static CC_INLINE uint32_t
last_known_seqno(uip_ipaddr_t *host)
{
  struct uaodv_rt_entry *route = uaodv_rt_lookup_any(host);

  if(route != NULL)
    return uip_htonl(route->hseqno);

  return 0;
}


static uint32_t rreq_id, my_hseqno;	/* In host byte order! */

#define NFWCACHE 16

static struct {
  uip_ipaddr_t orig;
  uint32_t id;
} fwcache[NFWCACHE];

static CC_INLINE int
fwc_lookup(const uip_ipaddr_t *orig, const uint32_t *id)
{
  unsigned n = (orig->u8[2] + orig->u8[3]) % NFWCACHE;
  return fwcache[n].id == *id && uip_ipaddr_cmp(&fwcache[n].orig, orig);
}

static CC_INLINE void
fwc_add(const uip_ipaddr_t *orig, const uint32_t *id)
{
  unsigned n = (orig->u8[2] + orig->u8[3]) % NFWCACHE;
  fwcache[n].id = *id;
  uip_ipaddr_copy(&fwcache[n].orig, orig);
}

#ifdef NDEBUG
#define PRINTF(...) do {} while (0)
#define print_debug(...) do{}while(0)
#else
#define PRINTF(...) printf(__VA_ARGS__)
#ifdef __GNUC__
static void
print_debug(const char *fmt, ...) __attribute__((format(printf, 1, 2)));
#endif /* __GNUC__ */
static void
print_debug(const char *fmt, ...)
{
  va_list ap;

  va_start(ap, fmt);
  printf("%d.%d.%d.%d: ", uip_ipaddr_to_quad(&uip_hostaddr));
  vprintf(fmt, ap);
  va_end(ap);
  return;
}
#endif

#define BUF ((struct uip_udpip_hdr *)&uip_buf[UIP_LLH_LEN])
#define uip_udp_sender() (&BUF->srcipaddr)

/*---------------------------------------------------------------------------*/
static void
sendto(const uip_ipaddr_t *dest, const void *buf, int len)
{
  /* XXX: this is a HACK! We're updating the uIP UDP connection
     "unicastconn" so that the destination address is the next-hop,
     and we're patching the "uip_udp_conn" variable so that it points
     the this connection instead. THIS IS NOT A NICE WAY TO DO THIS,
     but it is currently nicer than the alternative (requesting a new
     poll, and remembering the state, etc.). */
  
  uip_ipaddr_copy(&unicastconn->ripaddr, dest);
  uip_udp_conn = unicastconn;
  uip_udp_packet_send(unicastconn, buf, len);
}
/*---------------------------------------------------------------------------*/
#ifdef AODV_BAD_HOP_EXTENSION
static unsigned
add_rreq_extensions(void *_p)
{
  struct uaodv_bad_hop_ext *p = _p;
  uip_ipaddr_t *a = p->addrs;
  unsigned i, n;

#define SCALE_RETRANS_THRESHOLD (3*4)

  cc2420_check_remote(0xffff); /* Age table. */
  n = 0;
  for (i = 0; i < NNEIGBOURS; i++) {
    if (neigbours[i].nretrans >= SCALE_RETRANS_THRESHOLD
	&& neigbours[i].mac != 0xffff) {
      a->u16[0] = uip_hostaddr.u16[0];
      a->u16[1] = neigbours[i].mac;
      n++;
      if(n == 15)
	break;			/* Avoid buffer overrun */
      print_debug("BAD HOP %d.%d.%d.%d\t%d\n",
		  uip_ipaddr_to_quad(a), neigbours[i].nretrans);
    }
  }

  if(n == 0)
    return 0;

  p->type = RREQ_BAD_HOP_EXT;
  p->length = 2 + 4*n;		/* Two unused bytes + addresses */
  return 2 + p->length;		/* Type + len + extension data */
}
#else
#define add_rreq_extensions(p) 0 /* Don't add anything */
#endif

static void
send_rreq(uip_ipaddr_t *addr)
{
  struct uaodv_msg_rreq *rm = (struct uaodv_msg_rreq *)uip_appdata;
  int len;

  print_debug("send RREQ for %d.%d.%d.%d\n", uip_ipaddr_to_quad(addr));

  rm->type = UAODV_RREQ_TYPE;
  rm->dest_seqno = last_known_seqno(addr);
  if(rm->dest_seqno == 0)
    rm->flags = UAODV_RREQ_UNKSEQNO;
  else
    rm->flags = 0;
  rm->reserved = 0;
  rm->hop_count = 0;
  rm->rreq_id = uip_htonl(rreq_id++);
  uip_ipaddr_copy(&rm->dest_addr, addr);
  uip_gethostaddr(&rm->orig_addr);
  my_hseqno++;			/* Always */
  rm->orig_seqno = uip_htonl(my_hseqno);
  bcastconn->ttl = MY_NET_DIAMETER;
  len = sizeof(struct uaodv_msg_rreq);
  len += add_rreq_extensions(rm + 1);
  uip_udp_packet_send(bcastconn, rm, len);
}
/*---------------------------------------------------------------------------*/
static void
send_rrep(uip_ipaddr_t *dest, uip_ipaddr_t *nexthop, uip_ipaddr_t *orig,
	  uint32_t *seqno, unsigned hop_count)
{
  struct uaodv_msg_rrep *rm = (struct uaodv_msg_rrep *)uip_appdata;
  
  print_debug("send RREP orig=%d.%d.%d.%d hops=%d\n",
	      uip_ipaddr_to_quad(orig), hop_count);

  rm->type = UAODV_RREP_TYPE;
  rm->flags = 0;
  rm->prefix_sz = 0;		/* I.e a /32 route. */
  rm->hop_count = hop_count;
  uip_ipaddr_copy(&rm->orig_addr, orig);
  rm->dest_seqno = *seqno;
  uip_ipaddr_copy(&rm->dest_addr, dest);
  rm->lifetime = UIP_HTONL(MY_ROUTE_TIMEOUT);
  sendto(nexthop, rm, sizeof(struct uaodv_msg_rrep));
}
/*---------------------------------------------------------------------------*/
static void
send_rerr(uip_ipaddr_t *addr, uint32_t *seqno)
{
  struct uaodv_msg_rerr *rm = (struct uaodv_msg_rerr *)uip_appdata;
  
  print_debug("send RERR for %d.%d.%d.%d\n", uip_ipaddr_to_quad(addr));

  rm->type = UAODV_RERR_TYPE;
  rm->reserved = 0;
  rm->dest_count = 1;
  uip_ipaddr_copy(&rm->unreach[0].addr, addr);
  rm->unreach[0].seqno = *seqno;
  if(*seqno == 0)
    rm->flags = UAODV_RERR_UNKNOWN;
  else
    rm->flags = 0;

  uip_udp_packet_send(bcastconn, rm, sizeof(struct uaodv_msg_rerr));
}
/*---------------------------------------------------------------------------*/
static void
handle_incoming_rreq(void)
{
  struct uaodv_msg_rreq *rm = (struct uaodv_msg_rreq *)uip_appdata;
  uip_ipaddr_t dest_addr, orig_addr;
  struct uaodv_rt_entry *rt, *fw = NULL;
  
  print_debug("RREQ %d.%d.%d.%d -> %d.%d.%d.%d ttl=%u"
	      " orig=%d.%d.%d.%d seq=%lu hops=%u dest=%d.%d.%d.%d seq=%lu\n",
	      uip_ipaddr_to_quad(&BUF->srcipaddr),
	      uip_ipaddr_to_quad(&BUF->destipaddr),
	      BUF->ttl,
	      uip_ipaddr_to_quad(&rm->orig_addr), uip_ntohl(rm->orig_seqno),
	      rm->hop_count,
	      uip_ipaddr_to_quad(&rm->dest_addr), uip_ntohl(rm->dest_seqno));

  if(uip_ipaddr_cmp(&rm->orig_addr, &uip_hostaddr)) {
    return;			/* RREQ looped back! */
  }

#ifdef CC2420_RADIO
 {
   int ret = cc2420_check_remote(uip_udp_sender()->u16[1]);

   if(ret == REMOTE_YES) {
     print_debug("RREQ drop is remote\n");
     return;
   } else if (ret == REMOTE_NO) {
     /* Is neigbour, accept it. */
   } else if(cc2420_last_rssi < RSSI_THRESHOLD) {
     print_debug("RREQ drop %d %d\n", cc2420_last_rssi,
		 cc2420_last_correlation);
     return;
   }
 }
#endif

#ifdef AODV_BAD_HOP_EXTENSION
  if(uip_len > (sizeof(*rm) + 2)) {
    struct uaodv_bad_hop_ext *ext = (void *)(uip_appdata + sizeof(*rm));
    uint8_t *end = uip_appdata + uip_len;
    for(;
	(uint8_t *)ext < end;
	ext = (void *)((uint8_t *)ext + ext->length + 2)) {
      uint8_t *eend = (uint8_t *)ext + ext->length;
      if(eend > end)
	eend = end;

      if(ext->type == RREQ_BAD_HOP_EXT) {
	uip_ipaddr_t *a;
	for(a = ext->addrs; (uint8_t *)a < eend; a++) {
	  if(uip_ipaddr_cmp(a, &uip_hostaddr)) {
	    print_debug("BAD_HOP drop\n");
	    return;
	  }
	}
      }
    }
  }
#endif /* AODV_BAD_HOP_EXTENSION */

  /* New reverse route? */
  rt = uaodv_rt_lookup(&rm->orig_addr);
  if(rt == NULL
     || (SCMP32(uip_ntohl(rm->orig_seqno), rt->hseqno) > 0) /* New route. */
     || (SCMP32(uip_ntohl(rm->orig_seqno), rt->hseqno) == 0
	 && rm->hop_count < rt->hop_count)) { /* Better route. */
    print_debug("Inserting1\n");
    rt = uaodv_rt_add(&rm->orig_addr, uip_udp_sender(),
		      rm->hop_count, &rm->orig_seqno);
  }
    
  /* Check if it is for our address or a fresh route. */
  if(uip_ipaddr_cmp(&rm->dest_addr, &uip_hostaddr)
     || rm->flags & UAODV_RREQ_DESTONLY) {
    fw = NULL;
  } else {
    fw = uaodv_rt_lookup(&rm->dest_addr);
    if(!(rm->flags & UAODV_RREQ_UNKSEQNO)
       && fw != NULL
       && SCMP32(fw->hseqno, uip_ntohl(rm->dest_seqno)) <= 0) {
      fw = NULL;
    }
  }

  if (fw != NULL) {
    uint32_t net_seqno;

    print_debug("RREQ for known route\n");
    uip_ipaddr_copy(&dest_addr, &rm->dest_addr);
    uip_ipaddr_copy(&orig_addr, &rm->orig_addr);
    net_seqno = uip_htonl(fw->hseqno);
    send_rrep(&dest_addr, &rt->nexthop, &orig_addr, &net_seqno,
	      fw->hop_count + 1);
  } else if(uip_ipaddr_cmp(&rm->dest_addr, &uip_hostaddr)) {
    uint32_t net_seqno;

    print_debug("RREQ for our address\n");
    uip_ipaddr_copy(&dest_addr, &rm->dest_addr);
    uip_ipaddr_copy(&orig_addr, &rm->orig_addr);

    my_hseqno++;
    if(!(rm->flags & UAODV_RREQ_UNKSEQNO)
       && SCMP32(my_hseqno, uip_ntohl(rm->dest_seqno)) < 0) {
      print_debug("New my_hseqno %lu\n", my_hseqno); /* We have rebooted. */
      my_hseqno = uip_ntohl(rm->dest_seqno) + 1;
    }
    net_seqno = uip_htonl(my_hseqno);
    send_rrep(&dest_addr, &rt->nexthop, &orig_addr, &net_seqno, 0);
  } else if(BUF->ttl > 1) {
    int len;

    /* Have we seen this RREQ before? */
    if(fwc_lookup(&rm->orig_addr, &rm->rreq_id)) {
      print_debug("RREQ cached, not fwd\n");
      return;
    }
    fwc_add(&rm->orig_addr, &rm->rreq_id);

    print_debug("RREQ fwd\n");
    rm->hop_count++;
    bcastconn->ttl = BUF->ttl - 1;
    len = sizeof(struct uaodv_msg_rreq);
    len += add_rreq_extensions(rm + 1);
    uip_udp_packet_send(bcastconn, rm, len);
  }
}
/*---------------------------------------------------------------------------*/
static void
handle_incoming_rrep(void)
{
  struct uaodv_msg_rrep *rm = (struct uaodv_msg_rrep *)uip_appdata;
  struct uaodv_rt_entry *rt;

  /* Useless HELLO message? */
  if(uip_ipaddr_cmp(&BUF->destipaddr, &uip_broadcast_addr)) {
#ifdef AODV_RESPOND_TO_HELLOS
    uint32_t net_seqno;
#ifdef CC2420_RADIO
    int ret = cc2420_check_remote(uip_udp_sender()->u16[1]);

    if(ret == REMOTE_YES) {
      print_debug("HELLO drop is remote\n");
      return;
    } else if (ret == REMOTE_NO) {
      /* Is neigbour, accept it. */
    } else if(cc2420_last_rssi < RSSI_THRESHOLD) {
      print_debug("HELLO drop %d %d\n", cc2420_last_rssi, cc2420_last_correlation);
      return;
    }
#endif
    /* Sometimes it helps to send a non-requested RREP in response! */
    net_seqno = uip_htonl(my_hseqno);
    send_rrep(&uip_hostaddr, &BUF->srcipaddr, &BUF->srcipaddr, &net_seqno, 0);
#endif
    return;
  }

  print_debug("RREP %d.%d.%d.%d -> %d.%d.%d.%d"
	      " dest=%d.%d.%d.%d seq=%lu hops=%u orig=%d.%d.%d.%d\n",
	      uip_ipaddr_to_quad(&BUF->srcipaddr),
	      uip_ipaddr_to_quad(&BUF->destipaddr),
	      uip_ipaddr_to_quad(&rm->dest_addr), uip_ntohl(rm->dest_seqno),
	      rm->hop_count,
	      uip_ipaddr_to_quad(&rm->orig_addr));

  rt = uaodv_rt_lookup(&rm->dest_addr);

  /* New forward route? */
  if(rt == NULL || (SCMP32(uip_ntohl(rm->dest_seqno), rt->hseqno) > 0)) {
    print_debug("Inserting3\n");
    rt = uaodv_rt_add(&rm->dest_addr, uip_udp_sender(),
		      rm->hop_count, &rm->dest_seqno);
#ifdef CC2420_RADIO
    /* This link is ok since he is unicasting back to us! */
    cc2420_recv_ok(uip_udp_sender());
    print_debug("RREP recv ok %d %d\n",
		cc2420_last_rssi, cc2420_last_correlation);
#endif
  } else {
    print_debug("Not inserting\n");
  }

  /* Forward RREP towards originator? */
  if(uip_ipaddr_cmp(&rm->orig_addr, &uip_hostaddr)) {
    print_debug("ROUTE FOUND\n");
    if(rm->flags & UAODV_RREP_ACK) {
      struct uaodv_msg_rrep_ack *ack = (void *)uip_appdata;
      ack->type = UAODV_RREP_ACK_TYPE;
      ack->reserved = 0;
      sendto(uip_udp_sender(), ack, sizeof(*ack));
    }
  } else {
    rt = uaodv_rt_lookup(&rm->orig_addr);

    if(rt == NULL) {
      print_debug("RREP received, but no route back to originator... :-( \n");
      return;
    }

    if(rm->flags & UAODV_RREP_ACK) {
      print_debug("RREP with ACK request (ignored)!\n");
      /* Don't want any RREP-ACKs in return! */
      rm->flags &= ~UAODV_RREP_ACK;
    }

    rm->hop_count++;

    print_debug("Fwd RREP to %d.%d.%d.%d\n", uip_ipaddr_to_quad(&rt->nexthop));

    sendto(&rt->nexthop, rm, sizeof(struct uaodv_msg_rrep));
  }
}
/*---------------------------------------------------------------------------*/
static void
handle_incoming_rerr(void)
{
  struct uaodv_msg_rerr *rm = (struct uaodv_msg_rerr *)uip_appdata;
  struct uaodv_rt_entry *rt;

  print_debug("RERR %d.%d.%d.%d -> %d.%d.%d.%d"
	      " unreach=%d.%d.%d.%d seq=%lu\n",
	      uip_ipaddr_to_quad(&BUF->srcipaddr),
	      uip_ipaddr_to_quad(&BUF->destipaddr),
	      uip_ipaddr_to_quad((uip_ipaddr_t *)&rm->unreach[0]),
	      uip_ntohl(rm->unreach[0].seqno));

  if(uip_ipaddr_cmp(&rm->unreach[0].addr, &uip_hostaddr))
    return;

  rt = uaodv_rt_lookup_any(&rm->unreach[0].addr);
  if(rt != NULL && uip_ipaddr_cmp(&rt->nexthop, uip_udp_sender())) {
    if((rm->flags & UAODV_RERR_UNKNOWN) || rm->unreach[0].seqno == 0
       || SCMP32(rt->hseqno, uip_ntohl(rm->unreach[0].seqno)) <= 0) {
      rt->is_bad = 1;
      if(rm->flags & UAODV_RERR_UNKNOWN) {
	rm->flags &= ~UAODV_RERR_UNKNOWN;
	rm->unreach[0].seqno = uip_htonl(rt->hseqno);
      }
      print_debug("RERR rebroadcast\n");
      uip_udp_packet_send(bcastconn, rm, sizeof(struct uaodv_msg_rerr));
    }
  }
}
/*---------------------------------------------------------------------------*/
static void
handle_incoming_packet(void)
{
  struct uaodv_msg *m = (struct uaodv_msg *)uip_appdata;

  /*  print_debug("New UDP data, AODV packet type %d\n", m->type);*/
  switch(m->type) {
  case UAODV_RREQ_TYPE:
    handle_incoming_rreq();
    break;

  case UAODV_RREP_TYPE:
    handle_incoming_rrep();
    break;

  case UAODV_RERR_TYPE:
    handle_incoming_rerr();
    break;
  }

}
/*---------------------------------------------------------------------------*/
static enum {
  COMMAND_NONE,
  COMMAND_SEND_RREQ,
  COMMAND_SEND_RERR,
} command;

static uip_ipaddr_t bad_dest;
static uint32_t bad_seqno;		/* In network byte order! */

void
uaodv_bad_dest(uip_ipaddr_t *dest)
{
  struct uaodv_rt_entry *rt = uaodv_rt_lookup_any(dest);

  if(rt == NULL)
    bad_seqno = 0;		/* Or flag this in RERR? */
  else {
    rt->is_bad = 1;
    bad_seqno = uip_htonl(rt->hseqno);
  }

  uip_ipaddr_copy(&bad_dest, dest);
  command = COMMAND_SEND_RERR;
  process_post(&uaodv_process, PROCESS_EVENT_MSG, NULL);
}

static uip_ipaddr_t rreq_addr;
static struct timer next_time;

struct uaodv_rt_entry *
uaodv_request_route_to(uip_ipaddr_t *host)
{
  struct uaodv_rt_entry *route = uaodv_rt_lookup(host);

  if(route != NULL) {
    uaodv_rt_lru(route);
    return route;
  }

  /*
   * Broadcast protocols must be rate-limited!
   */
  if(!timer_expired(&next_time)) {
    return NULL;
  }

  if(command != COMMAND_NONE) {
    return NULL;
  }

  uip_ipaddr_copy(&rreq_addr, host);
  command = COMMAND_SEND_RREQ;
  process_post(&uaodv_process, PROCESS_EVENT_MSG, NULL);
  timer_set(&next_time, CLOCK_SECOND/8); /* Max 10/s per RFC3561. */
  return NULL;
}

PROCESS_THREAD(uaodv_process, ev, data)
{
  PROCESS_EXITHANDLER(goto exit);

  PROCESS_BEGIN();

  printf("uaodv_process starting %lu\n", (unsigned long) my_hseqno);

  bcastconn = udp_broadcast_new(UIP_HTONS(UAODV_UDPPORT), NULL);
  unicastconn = udp_broadcast_new(UIP_HTONS(UAODV_UDPPORT), NULL);
  
  while(1) {
    PROCESS_WAIT_EVENT();

    if(ev == tcpip_event) {
      if(uip_newdata()) {
	handle_incoming_packet();
	continue;
      }
      if(uip_poll()) {
	if(command == COMMAND_SEND_RREQ) {
	  if(uaodv_rt_lookup(&rreq_addr) == NULL)
	    send_rreq(&rreq_addr);
	} else if (command == COMMAND_SEND_RERR) {
	  send_rerr(&bad_dest, &bad_seqno);
	}
	command = COMMAND_NONE;
	continue;
      }
    }

    if(ev == PROCESS_EVENT_MSG) {
      tcpip_poll_udp(bcastconn);
    }
  }

 exit:
  command = COMMAND_NONE;
  uaodv_rt_flush_all();
  uip_udp_remove(bcastconn);
  bcastconn = NULL;
  uip_udp_remove(unicastconn);
  unicastconn = NULL;
  printf("uaodv_process exiting\n");
  PROCESS_END();
}
/*---------------------------------------------------------------------------*/