/* AS path management routines.
   Copyright (C) 1996, 97, 98, 99 Kunihiro Ishiguro
   Copyright (C) 2005 Sun Microsystems, Inc.

This file is part of GNU Zebra.

GNU Zebra is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.

GNU Zebra is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Zebra; see the file COPYING.  If not, write to the Free
Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

#include <zebra.h>

#include "hash.h"
#include "memory.h"
#include "vector.h"
#include "vty.h"
#include "str.h"
#include "log.h"
#include "stream.h"
#include "jhash.h"

#include "bgpd/bgpd.h"
#include "bgpd/bgp_aspath.h"
#include "bgpd/bgp_debug.h"
#include "bgpd/bgp_attr.h"

/* Attr. Flags and Attr. Type Code. */
#define AS_HEADER_SIZE        2	 

/* Now FOUR octets are used for AS value. */
#define AS_VALUE_SIZE         sizeof (as_t)
/* This is the old one */
#define AS16_VALUE_SIZE	      sizeof (as16_t)

/* Maximum protocol segment length value */
#define AS_SEGMENT_MAX		255

/* The following length and size macros relate specifically to Quagga's
 * internal representation of AS-Segments, not per se to the on-wire
 * sizes and lengths.  At present (200508) they sort of match, however
 * the ONLY functions which should now about the on-wire syntax are
 * aspath_put, assegment_put and assegment_parse.
 *
 * aspath_put returns bytes written, the only definitive record of
 * size of wire-format attribute..
 */

/* Calculated size in bytes of ASN segment data to hold N ASN's */
#define ASSEGMENT_DATA_SIZE(N,S) \
	((N) * ( (S) ? AS_VALUE_SIZE : AS16_VALUE_SIZE) )

/* Calculated size of segment struct to hold N ASN's */
#define ASSEGMENT_SIZE(N,S)  (AS_HEADER_SIZE + ASSEGMENT_DATA_SIZE (N,S))

/* AS segment octet length. */
#define ASSEGMENT_LEN(X,S) ASSEGMENT_SIZE((X)->length,S)

/* AS_SEQUENCE segments can be packed together */
/* Can the types of X and Y be considered for packing? */
#define ASSEGMENT_TYPES_PACKABLE(X,Y) \
  ( ((X)->type == (Y)->type) \
   && ((X)->type == AS_SEQUENCE))
/* Types and length of X,Y suitable for packing? */
#define ASSEGMENTS_PACKABLE(X,Y) \
  ( ASSEGMENT_TYPES_PACKABLE( (X), (Y)) \
   && ( ((X)->length + (Y)->length) <= AS_SEGMENT_MAX ) )

/* As segment header - the on-wire representation 
 * NOT the internal representation!
 */
struct assegment_header
{
  u_char type;
  u_char length;
};

/* Hash for aspath.  This is the top level structure of AS path. */
static struct hash *ashash;

/* Stream for SNMP. See aspath_snmp_pathseg */
static struct stream *snmp_stream;

static inline as_t *
assegment_data_new (int num)
{
  return (XCALLOC (MTYPE_AS_SEG_DATA, ASSEGMENT_DATA_SIZE (num, 1)));
}

static inline void
assegment_data_free (as_t *asdata)
{
  XFREE (MTYPE_AS_SEG_DATA,asdata);
}

/* Get a new segment. Note that 0 is an allowed length,
 * and will result in a segment with no allocated data segment.
 * the caller should immediately assign data to the segment, as the segment
 * otherwise is not generally valid
 */
static struct assegment *
assegment_new (u_char type, u_short length)
{
  struct assegment *new;
  
  new = XCALLOC (MTYPE_AS_SEG, sizeof (struct assegment));
  
  if (length)
    new->as = assegment_data_new (length);
  
  new->length = length;
  new->type = type;
  
  return new;
}

static void
assegment_free (struct assegment *seg)
{
  if (!seg)
    return;
  
  if (seg->as)
    XFREE (MTYPE_AS_SEG_DATA, seg->as);
  memset (seg, 0xfe, sizeof(struct assegment));
  XFREE (MTYPE_AS_SEG, seg);
  
  return;
}

/* free entire chain of segments */
static void
assegment_free_all (struct assegment *seg)
{
  struct assegment *prev;
  
  while (seg)
    {
      prev = seg;
      seg = seg->next;
      assegment_free (prev);
    }
}

/* Duplicate just the given assegment and its data */
static struct assegment *
assegment_dup (struct assegment *seg)
{
  struct assegment *new;
  
  new = assegment_new (seg->type, seg->length);
  memcpy (new->as, seg->as, ASSEGMENT_DATA_SIZE (new->length, 1) );
    
  return new;
}

/* Duplicate entire chain of assegments, return the head */
static struct assegment *
assegment_dup_all (struct assegment *seg)
{
  struct assegment *new = NULL;
  struct assegment *head = NULL;
  
  while (seg)
    {
      if (head)
        {
          new->next = assegment_dup (seg);
          new = new->next;
        }
      else
        head = new = assegment_dup (seg);
      
      seg = seg->next;
    }
  return head;
}

/* prepend the as number to given segment, given num of times */
static struct assegment *
assegment_prepend_asns (struct assegment *seg, as_t asnum, int num)
{
  as_t *newas;
  
  if (!num)
    return seg;
  
  if (num >= AS_SEGMENT_MAX)
    return seg; /* we don't do huge prepends */
  
  newas = assegment_data_new (seg->length + num);
  
  if (newas)
    {
      int i;
      for (i = 0; i < num; i++)
        newas[i] = asnum;
      
      memcpy (newas + num, seg->as, ASSEGMENT_DATA_SIZE (seg->length, 1));
      XFREE (MTYPE_AS_SEG_DATA, seg->as);
      seg->as = newas; 
      seg->length += num;
      return seg;
    }

  assegment_free_all (seg);
  return NULL;
}

/* append given array of as numbers to the segment */
static struct assegment *
assegment_append_asns (struct assegment *seg, as_t *asnos, int num)
{
  as_t *newas;
  
  newas = XREALLOC (MTYPE_AS_SEG_DATA, seg->as,
		      ASSEGMENT_DATA_SIZE (seg->length + num, 1));

  if (newas)
    {
      seg->as = newas;
      memcpy (seg->as + seg->length, asnos, ASSEGMENT_DATA_SIZE(num, 1));
      seg->length += num;
      return seg;
    }

  assegment_free_all (seg);
  return NULL;
}

static int
int_cmp (const void *p1, const void *p2)
{
  const as_t *as1 = p1;
  const as_t *as2 = p2;
  
  return (*as1 == *as2) 
          ? 0 : ( (*as1 > *as2) ? 1 : -1);
}

/* normalise the segment.
 * In particular, merge runs of AS_SEQUENCEs into one segment
 * Internally, we do not care about the wire segment length limit, and
 * we want each distinct AS_PATHs to have the exact same internal
 * representation - eg, so that our hashing actually works..
 */
static struct assegment *
assegment_normalise (struct assegment *head)
{
  struct assegment *seg = head, *pin;
  struct assegment *tmp;
  
  if (!head)
    return head;
  
  while (seg)
    {
      pin = seg;
      
      /* Sort values SET segments, for determinism in paths to aid
       * creation of hash values / path comparisons
       * and because it helps other lesser implementations ;)
       */
      if (seg->type == AS_SET || seg->type == AS_CONFED_SET)
      	{
	  int tail = 0;
	  int i;
	  
	  qsort (seg->as, seg->length, sizeof(as_t), int_cmp);
	  
	  /* weed out dupes */
	  for (i=1; i < seg->length; i++)
	    {
	      if (seg->as[tail] == seg->as[i])
	      	continue;
	      
	      tail++;
	      if (tail < i)
	      	seg->as[tail] = seg->as[i];
	    }
	  /* seg->length can be 0.. */
	  if (seg->length)
	    seg->length = tail + 1;
	}

      /* read ahead from the current, pinned segment while the segments
       * are packable/mergeable. Append all following packable segments
       * to the segment we have pinned and remove these appended
       * segments.
       */      
      while (pin->next && ASSEGMENT_TYPES_PACKABLE(pin, pin->next))
        {
          tmp = pin->next;
          seg = pin->next;
          
          /* append the next sequence to the pinned sequence */
          pin = assegment_append_asns (pin, seg->as, seg->length);
          
          /* bypass the next sequence */
          pin->next = seg->next;
          
          /* get rid of the now referenceless segment */
          assegment_free (tmp);
          
        }

      seg = pin->next;
    }
  return head;
}

static struct aspath *
aspath_new (void)
{
  return XCALLOC (MTYPE_AS_PATH, sizeof (struct aspath));
}

/* Free AS path structure. */
void
aspath_free (struct aspath *aspath)
{
  if (!aspath)
    return;
  if (aspath->segments)
    assegment_free_all (aspath->segments);
  if (aspath->str)
    XFREE (MTYPE_AS_STR, aspath->str);
  XFREE (MTYPE_AS_PATH, aspath);
}

/* Unintern aspath from AS path bucket. */
void
aspath_unintern (struct aspath *aspath)
{
  struct aspath *ret;

  if (aspath->refcnt)
    aspath->refcnt--;

  if (aspath->refcnt == 0)
    {
      /* This aspath must exist in aspath hash table. */
      ret = hash_release (ashash, aspath);
      assert (ret != NULL);
      aspath_free (aspath);
    }
}

/* Return the start or end delimiters for a particular Segment type */
#define AS_SEG_START 0
#define AS_SEG_END 1
static char
aspath_delimiter_char (u_char type, u_char which)
{
  int i;
  struct
  {
    int type;
    char start;
    char end;
  } aspath_delim_char [] =
    {
      { AS_SET,             '{', '}' },
      { AS_CONFED_SET,      '[', ']' },
      { AS_CONFED_SEQUENCE, '(', ')' },
      { 0 }
    };

  for (i = 0; aspath_delim_char[i].type != 0; i++)
    {
      if (aspath_delim_char[i].type == type)
	{
	  if (which == AS_SEG_START)
	    return aspath_delim_char[i].start;
	  else if (which == AS_SEG_END)
	    return aspath_delim_char[i].end;
	}
    }
  return ' ';
}

/* countup asns from this segment and index onward */
static int
assegment_count_asns (struct assegment *seg, int from)
{
  int count = 0;
  while (seg)
    {
      if (!from)
        count += seg->length;
      else
        {
          count += (seg->length - from);
          from = 0;
        }
      seg = seg->next;
    }
  return count;
}

unsigned int
aspath_count_confeds (struct aspath *aspath)
{
  int count = 0;
  struct assegment *seg = aspath->segments;
  
  while (seg)
    {
      if (seg->type == AS_CONFED_SEQUENCE)
        count += seg->length;
      else if (seg->type == AS_CONFED_SET)
        count++;
      
      seg = seg->next;
    }
  return count;
}

unsigned int
aspath_count_hops (struct aspath *aspath)
{
  int count = 0;
  struct assegment *seg = aspath->segments;
  
  while (seg)
    {
      if (seg->type == AS_SEQUENCE)
        count += seg->length;
      else if (seg->type == AS_SET)
        count++;
      
      seg = seg->next;
    }
  return count;
}

/* Estimate size aspath /might/ take if encoded into an
 * ASPATH attribute.
 *
 * This is a quick estimate, not definitive! aspath_put()
 * may return a different number!!
 */
unsigned int
aspath_size (struct aspath *aspath)
{
  int size = 0;
  struct assegment *seg = aspath->segments;
  
  while (seg)
    {
      size += ASSEGMENT_SIZE(seg->length, 1);
      seg = seg->next;
    }
  return size;
}

/* Return highest public ASN in path */
as_t
aspath_highest (struct aspath *aspath)
{
  struct assegment *seg = aspath->segments;
  as_t highest = 0;
  unsigned int i;
  
  while (seg)
    {
      for (i = 0; i < seg->length; i++)
        if (seg->as[i] > highest
            && (seg->as[i] < BGP_PRIVATE_AS_MIN
                || seg->as[i] > BGP_PRIVATE_AS_MAX))
	  highest = seg->as[i];
      seg = seg->next;
    }
  return highest;
}

/* Return 1 if there are any 4-byte ASes in the path */
unsigned int
aspath_has_as4 (struct aspath *aspath)
{
  struct assegment *seg = aspath->segments;
  unsigned int i;
  
  while (seg)
    {
      for (i = 0; i < seg->length; i++)
        if (seg->as[i] > BGP_AS_MAX)
	  return 1;
      seg = seg->next;
    }
  return 0;
}

/* Convert aspath structure to string expression. */
static char *
aspath_make_str_count (struct aspath *as)
{
  struct assegment *seg;
  int str_size;
  int len = 0;
  char *str_buf;

  /* Empty aspath. */
  if (!as->segments)
    {
      str_buf = XMALLOC (MTYPE_AS_STR, 1);
      str_buf[0] = '\0';
      return str_buf;
    }
  
  seg = as->segments;
  
  /* ASN takes 5 to 10 chars plus seperator, see below.
   * If there is one differing segment type, we need an additional
   * 2 chars for segment delimiters, and the final '\0'.
   * Hopefully this is large enough to avoid hitting the realloc
   * code below for most common sequences.
   *
   * This was changed to 10 after the well-known BGP assertion, which
   * had hit some parts of the Internet in May of 2009.
   */
#define ASN_STR_LEN (10 + 1)
  str_size = MAX (assegment_count_asns (seg, 0) * ASN_STR_LEN + 2 + 1,
                  ASPATH_STR_DEFAULT_LEN);
  str_buf = XMALLOC (MTYPE_AS_STR, str_size);

  while (seg)
    {
      int i;
      char seperator;
      
      /* Check AS type validity. Set seperator for segment */
      switch (seg->type)
        {
          case AS_SET:
          case AS_CONFED_SET:
            seperator = ',';
            break;
          case AS_SEQUENCE:
          case AS_CONFED_SEQUENCE:
            seperator = ' ';
            break;
          default:
            XFREE (MTYPE_AS_STR, str_buf);
            return NULL;
        }
      
      /* We might need to increase str_buf, particularly if path has
       * differing segments types, our initial guesstimate above will
       * have been wrong. Need 10 chars for ASN, a seperator each and
       * potentially two segment delimiters, plus a space between each
       * segment and trailing zero.
       *
       * This definitely didn't work with the value of 5 bytes and
       * 32-bit ASNs.
       */
#define SEGMENT_STR_LEN(X) (((X)->length * ASN_STR_LEN) + 2 + 1 + 1)
      if ( (len + SEGMENT_STR_LEN(seg)) > str_size)
        {
          str_size = len + SEGMENT_STR_LEN(seg);
          str_buf = XREALLOC (MTYPE_AS_STR, str_buf, str_size);
        }
#undef ASN_STR_LEN
#undef SEGMENT_STR_LEN
      
      if (seg->type != AS_SEQUENCE)
        len += snprintf (str_buf + len, str_size - len, 
			 "%c", 
                         aspath_delimiter_char (seg->type, AS_SEG_START));
      
      /* write out the ASNs, with their seperators, bar the last one*/
      for (i = 0; i < seg->length; i++)
        {
          len += snprintf (str_buf + len, str_size - len, "%u", seg->as[i]);
          
          if (i < (seg->length - 1))
            len += snprintf (str_buf + len, str_size - len, "%c", seperator);
        }
      
      if (seg->type != AS_SEQUENCE)
        len += snprintf (str_buf + len, str_size - len, "%c", 
                        aspath_delimiter_char (seg->type, AS_SEG_END));
      if (seg->next)
        len += snprintf (str_buf + len, str_size - len, " ");
      
      seg = seg->next;
    }
  
  assert (len < str_size);
  
  str_buf[len] = '\0';

  return str_buf;
}

static void
aspath_str_update (struct aspath *as)
{
  if (as->str)
    XFREE (MTYPE_AS_STR, as->str);
  as->str = aspath_make_str_count (as);
}

/* Intern allocated AS path. */
struct aspath *
aspath_intern (struct aspath *aspath)
{
  struct aspath *find;
  
  /* Assert this AS path structure is not interned. */
  assert (aspath->refcnt == 0);

  /* Check AS path hash. */
  find = hash_get (ashash, aspath, hash_alloc_intern);

  if (find != aspath)
    aspath_free (aspath);

  find->refcnt++;

  if (! find->str)
    find->str = aspath_make_str_count (find);

  return find;
}

/* Duplicate aspath structure.  Created same aspath structure but
   reference count and AS path string is cleared. */
struct aspath *
aspath_dup (struct aspath *aspath)
{
  struct aspath *new;

  new = XCALLOC (MTYPE_AS_PATH, sizeof (struct aspath));

  if (aspath->segments)
    new->segments = assegment_dup_all (aspath->segments);
  else
    new->segments = NULL;

  new->str = aspath_make_str_count (aspath);

  return new;
}

static void *
aspath_hash_alloc (void *arg)
{
  struct aspath *aspath;

  /* New aspath structure is needed. */
  aspath = aspath_dup (arg);
  
  /* Malformed AS path value. */
  if (! aspath->str)
    {
      aspath_free (aspath);
      return NULL;
    }

  return aspath;
}

/* parse as-segment byte stream in struct assegment
 *
 * Returns NULL if the AS_PATH or AS4_PATH is not valid.
 */
static struct assegment *
assegments_parse (struct stream *s, size_t length, int use32bit, int as4_path)
{
  struct assegment_header segh;
  struct assegment *seg, *prev = NULL, *head = NULL;
  
  assert (length > 0);  /* does not expect empty AS_PATH or AS4_PATH    */
  
  if (BGP_DEBUG (as4, AS4_SEGMENT))
    zlog_debug ("[AS4SEG] Parse aspath segment: got total byte length %lu",
		(unsigned long) length);

  /* double check that length does not exceed stream    */
  if (STREAM_READABLE(s) < length)
    return NULL;
  
  /* deal with each segment in turn                             */
  while (length > 0)
    {
      int i;
      size_t seg_size;
      
      /* softly softly, get the header first on its own */
      if (length < AS_HEADER_SIZE)
        {
          assegment_free_all (head);
          return NULL;
        }
      
      segh.type = stream_getc (s);
      segh.length = stream_getc (s);
      
      seg_size = ASSEGMENT_SIZE(segh.length, use32bit);
                                      /* includes the header bytes */

      if (BGP_DEBUG (as4, AS4_SEGMENT))
	zlog_debug ("[AS4SEG] Parse aspath segment: got type %d, length %d",
                    segh.type, segh.length);
      
      switch (segh.type)
        {
          case AS_SEQUENCE:
          case AS_SET:
            break ;

          case AS_CONFED_SEQUENCE:
          case AS_CONFED_SET:
            if (!as4_path)
              break ;
              /* RFC4893 3: "invalid for the AS4_PATH attribute"            */
              /* fall through */

          default:    /* reject unknown or invalid AS_PATH segment types  */
            seg_size = 0 ;
        }
     
     /* Stop now if segment is not valid (discarding anything collected to date)
      *
      * RFC4271 4.3, Path Attributes, b) AS_PATH:
      *
      *   "path segment value field contains one or more AS numbers"
           */
      if ((seg_size == 0) || (seg_size > length) || (segh.length == 0))
        {
          assegment_free_all (head);
          return NULL;
        }
      
      length -= seg_size ;
      
      /* now its safe to trust lengths */
      seg = assegment_new (segh.type, segh.length);
      
      if (head)
        prev->next = seg;
      else /* it's the first segment */
        head = prev = seg;
      
      for (i = 0; i < segh.length; i++)
	seg->as[i] = (use32bit) ? stream_getl (s) : stream_getw (s);

      if (BGP_DEBUG (as4, AS4_SEGMENT))
	zlog_debug ("[AS4SEG] Parse aspath segment: length left: %lu",
	            (unsigned long) length);
      
      prev = seg;
    }
 
  return assegment_normalise (head);
}

/* AS path parse function -- parses AS_PATH and AS4_PATH attributes
 *
 * Requires: s        -- stream, currently positioned before first segment
 *                       of AS_PATH or AS4_PATH (ie after attribute header)
 *           length   -- length of the value of the AS_PATH or AS4_PATH
 *           use32bit -- true <=> 4Byte ASN, otherwise 2Byte ASN
 *           as4_path -- true <=> AS4_PATH, otherwise AS_PATH
 *
 * Returns: if valid: address of struct aspath in the hash of known aspaths,
 *                    with reference count incremented.
 *              else: NULL
 *
 * NB: empty AS path (length == 0) is valid.  The returned struct aspath will
 *     have segments == NULL and str == zero length string (unique).
 */
struct aspath *
aspath_parse (struct stream *s, size_t length, int use32bit, int as4_path)
{
  struct aspath as;
  struct aspath *find;

  /* Parse each segment and construct normalised list of struct assegment */
  memset (&as, 0, sizeof (struct aspath));
  if (length != 0)
    {
      as.segments = assegments_parse (s, length, use32bit, as4_path);

      if (as.segments == NULL)
        return NULL ;   /* Invalid AS_PATH or AS4_PATH  */
    } ;
  
  /* If already same aspath exist then return it. */
  find = hash_get (ashash, &as, aspath_hash_alloc);
  
  assert(find) ;        /* valid aspath, so must find or create */
  
  /* aspath_hash_alloc dupes segments too. that probably could be
   * optimised out.
   */
  assegment_free_all (as.segments);
  if (as.str)
    XFREE (MTYPE_AS_STR, as.str);
  
  find->refcnt++;

  return find;
}

static inline void
assegment_data_put (struct stream *s, as_t *as, int num, int use32bit)
{
  int i;
  assert (num <= AS_SEGMENT_MAX);
  
  for (i = 0; i < num; i++)
    if ( use32bit )
      stream_putl (s, as[i]);
    else
      {
        if ( as[i] <= BGP_AS_MAX )
	  stream_putw(s, as[i]);
	else
	  stream_putw(s, BGP_AS_TRANS);
      }
}

static inline size_t
assegment_header_put (struct stream *s, u_char type, int length)
{
  size_t lenp;
  assert (length <= AS_SEGMENT_MAX);
  stream_putc (s, type);
  lenp = stream_get_endp (s);
  stream_putc (s, length);
  return lenp;
}

/* write aspath data to stream */
size_t
aspath_put (struct stream *s, struct aspath *as, int use32bit )
{
  struct assegment *seg = as->segments;
  size_t bytes = 0;
  
  if (!seg || seg->length == 0)
    return 0;
  
  if (seg)
    {
      /*
       * Hey, what do we do when we have > STREAM_WRITABLE(s) here?
       * At the moment, we would write out a partial aspath, and our peer
       * will complain and drop the session :-/
       *
       * The general assumption here is that many things tested will
       * never happen.  And, in real live, up to now, they have not.
       */
      while (seg && (ASSEGMENT_LEN(seg, use32bit) <= STREAM_WRITEABLE(s)))
        {
          struct assegment *next = seg->next;
          int written = 0;
          int asns_packed = 0;
          size_t lenp;
          
          /* Overlength segments have to be split up */
          while ( (seg->length - written) > AS_SEGMENT_MAX)
            {
              assegment_header_put (s, seg->type, AS_SEGMENT_MAX);
              assegment_data_put (s, seg->as, AS_SEGMENT_MAX, use32bit);
              written += AS_SEGMENT_MAX;
              bytes += ASSEGMENT_SIZE (written, use32bit);
            }
          
          /* write the final segment, probably is also the first */
          lenp = assegment_header_put (s, seg->type, seg->length - written);
          assegment_data_put (s, (seg->as + written), seg->length - written, 
                              use32bit);
          
          /* Sequence-type segments can be 'packed' together
           * Case of a segment which was overlength and split up
           * will be missed here, but that doesn't matter.
           */
          while (next && ASSEGMENTS_PACKABLE (seg, next))
            {
              /* NB: We should never normally get here given we
               * normalise aspath data when parse them. However, better
               * safe than sorry. We potentially could call
               * assegment_normalise here instead, but it's cheaper and
               * easier to do it on the fly here rather than go through
               * the segment list twice every time we write out
               * aspath's.
               */
              
              /* Next segment's data can fit in this one */
              assegment_data_put (s, next->as, next->length, use32bit);
              
              /* update the length of the segment header */
	      stream_putc_at (s, lenp, seg->length - written + next->length);
              asns_packed += next->length;
               
	      next = next->next;
	    }
          
          bytes += ASSEGMENT_SIZE (seg->length - written + asns_packed, 
				   use32bit);
          seg = next;
        }
    }
  return bytes;
}

/* This is for SNMP BGP4PATHATTRASPATHSEGMENT
 * We have no way to manage the storage, so we use a static stream
 * wrapper around aspath_put.
 */
u_char *
aspath_snmp_pathseg (struct aspath *as, size_t *varlen)
{
#define SNMP_PATHSEG_MAX 1024

  if (!snmp_stream)
    snmp_stream = stream_new (SNMP_PATHSEG_MAX);
  else
    stream_reset (snmp_stream);
  
  if (!as)
    {
      *varlen = 0;
      return NULL;
    }
  aspath_put (snmp_stream, as, 0); /* use 16 bit for now here */
  
  *varlen = stream_get_endp (snmp_stream);
  return stream_pnt(snmp_stream);
}
      
#define min(A,B) ((A) < (B) ? (A) : (B))

static struct assegment *
aspath_aggregate_as_set_add (struct aspath *aspath, struct assegment *asset,
			     as_t as)
{
  int i;

  /* If this is first AS set member, create new as-set segment. */
  if (asset == NULL)
    {
      asset = assegment_new (AS_SET, 1);
      if (! aspath->segments)
	aspath->segments = asset;
      else
        {
          struct assegment *seg = aspath->segments;
          while (seg->next)
            seg = seg->next;
          seg->next = asset;
        }
      asset->type = AS_SET;
      asset->length = 1;
      asset->as[0] = as;
    }
  else
    {
      /* Check this AS value already exists or not. */
      for (i = 0; i < asset->length; i++)
	if (asset->as[i] == as)
	  return asset;
      
      asset->length++;
      asset->as = XREALLOC (MTYPE_AS_SEG_DATA, asset->as, 
                            asset->length * AS_VALUE_SIZE);
      asset->as[asset->length - 1] = as;
    }
  

  return asset;
}

/* Modify as1 using as2 for aggregation. */
struct aspath *
aspath_aggregate (struct aspath *as1, struct aspath *as2)
{
  int i;
  int minlen;
  int match;
  int from;
  struct assegment *seg1 = as1->segments;
  struct assegment *seg2 = as2->segments;
  struct aspath *aspath = NULL;
  struct assegment *asset;
  struct assegment *prevseg = NULL;

  match = 0;
  minlen = 0;
  aspath = NULL;
  asset = NULL;

  /* First of all check common leading sequence. */
  while (seg1 && seg2)
    {      
      /* Check segment type. */
      if (seg1->type != seg2->type)
	break;

      /* Minimum segment length. */
      minlen = min (seg1->length, seg2->length);

      for (match = 0; match < minlen; match++)
	if (seg1->as[match] != seg2->as[match])
	  break;

      if (match)
	{
	  struct assegment *seg = assegment_new (seg1->type, 0);
	  
	  seg = assegment_append_asns (seg, seg1->as, match);

	  if (! aspath)
	    {
	      aspath = aspath_new ();
	      aspath->segments = seg;
	     }
	  else
	    prevseg->next = seg;
	  
	  prevseg = seg;
	}

      if (match != minlen || match != seg1->length 
	  || seg1->length != seg2->length)
	break;
      
      seg1 = seg1->next;
      seg2 = seg2->next;
    }

  if (! aspath)
    aspath = aspath_new();

  /* Make as-set using rest of all information. */
  from = match;
  while (seg1)
    {
      for (i = from; i < seg1->length; i++)
	asset = aspath_aggregate_as_set_add (aspath, asset, seg1->as[i]);
      
      from = 0;
      seg1 = seg1->next;
    }

  from = match;
  while (seg2)
    {
      for (i = from; i < seg2->length; i++)
	asset = aspath_aggregate_as_set_add (aspath, asset, seg2->as[i]);

      from = 0;
      seg2 = seg2->next;
    }
  
  assegment_normalise (aspath->segments);
  aspath_str_update (aspath);
  return aspath;
}

/* When a BGP router receives an UPDATE with an MP_REACH_NLRI
   attribute, check the leftmost AS number in the AS_PATH attribute is
   or not the peer's AS number. */ 
int
aspath_firstas_check (struct aspath *aspath, as_t asno)
{
  if ( (aspath == NULL) || (aspath->segments == NULL) )
    return 0;
  
  if (aspath->segments
      && (aspath->segments->type == AS_SEQUENCE)
      && (aspath->segments->as[0] == asno ))
    return 1;

  return 0;
}

/* AS path loop check.  If aspath contains asno then return >= 1. */
int
aspath_loop_check (struct aspath *aspath, as_t asno)
{
  struct assegment *seg;
  int count = 0;

  if ( (aspath == NULL) || (aspath->segments == NULL) )
    return 0;
  
  seg = aspath->segments;
  
  while (seg)
    {
      int i;
      
      for (i = 0; i < seg->length; i++)
	if (seg->as[i] == asno)
	  count++;
      
      seg = seg->next;
    }
  return count;
}

/* When all of AS path is private AS return 1.  */
int
aspath_private_as_check (struct aspath *aspath)
{
  struct assegment *seg;
  
  if ( !(aspath && aspath->segments) )
    return 0;
    
  seg = aspath->segments;

  while (seg)
    {
      int i;
      
      for (i = 0; i < seg->length; i++)
	{
	  if ( (seg->as[i] < BGP_PRIVATE_AS_MIN)
	      || (seg->as[i] > BGP_PRIVATE_AS_MAX) )
	    return 0;
	}
      seg = seg->next;
    }
  return 1;
}

/* AS path confed check.  If aspath contains confed set or sequence then return 1. */
int
aspath_confed_check (struct aspath *aspath)
{
  struct assegment *seg;

  if ( !(aspath && aspath->segments) )
    return 0;

  seg = aspath->segments;

  while (seg)
    {
      if (seg->type == AS_CONFED_SET || seg->type == AS_CONFED_SEQUENCE)
	  return 1;
      seg = seg->next;
    }
  return 0;
}

/* Leftmost AS path segment confed check.  If leftmost AS segment is of type
  AS_CONFED_SEQUENCE or AS_CONFED_SET then return 1.  */
int
aspath_left_confed_check (struct aspath *aspath)
{

  if ( !(aspath && aspath->segments) )
    return 0;

  if ( (aspath->segments->type == AS_CONFED_SEQUENCE)
      || (aspath->segments->type == AS_CONFED_SET) )
    return 1;

  return 0;
}

/* Merge as1 to as2.  as2 should be uninterned aspath. */
static struct aspath *
aspath_merge (struct aspath *as1, struct aspath *as2)
{
  struct assegment *last, *new;

  if (! as1 || ! as2)
    return NULL;

  last = new = assegment_dup_all (as1->segments);
  
  /* find the last valid segment */
  while (last && last->next)
    last = last->next;
  
  last->next = as2->segments;
  as2->segments = new;
  aspath_str_update (as2);
  return as2;
}

/* Prepend as1 to as2.  as2 should be uninterned aspath. */
struct aspath *
aspath_prepend (struct aspath *as1, struct aspath *as2)
{
  struct assegment *seg1;
  struct assegment *seg2;

  if (! as1 || ! as2)
    return NULL;
  
  seg1 = as1->segments;
  seg2 = as2->segments;
  
  /* If as2 is empty, only need to dupe as1's chain onto as2 */
  if (seg2 == NULL)
    {
      as2->segments = assegment_dup_all (as1->segments);
      aspath_str_update (as2);
      return as2;
    }
  
  /* If as1 is empty AS, no prepending to do. */
  if (seg1 == NULL)
    return as2;
  
  /* find the tail as1's segment chain. */
  while (seg1 && seg1->next)
    seg1 = seg1->next;

  /* Delete any AS_CONFED_SEQUENCE segment from as2. */
  if (seg1->type == AS_SEQUENCE && seg2->type == AS_CONFED_SEQUENCE)
    as2 = aspath_delete_confed_seq (as2);

  /* Compare last segment type of as1 and first segment type of as2. */
  if (seg1->type != seg2->type)
    return aspath_merge (as1, as2);

  if (seg1->type == AS_SEQUENCE)
    {
      /* We have two chains of segments, as1->segments and seg2, 
       * and we have to attach them together, merging the attaching
       * segments together into one.
       * 
       * 1. dupe as1->segments onto head of as2
       * 2. merge seg2's asns onto last segment of this new chain
       * 3. attach chain after seg2
       */
      
      /* dupe as1 onto as2's head */
      seg1 = as2->segments = assegment_dup_all (as1->segments);
      
      /* refind the tail of as2, reusing seg1 */
      while (seg1 && seg1->next)
        seg1 = seg1->next;
      
      /* merge the old head, seg2, into tail, seg1 */
      seg1 = assegment_append_asns (seg1, seg2->as, seg2->length);
      
      /* bypass the merged seg2, and attach any chain after it to
       * chain descending from as2's head
       */
      seg1->next = seg2->next;
      
      /* seg2 is now referenceless and useless*/
      assegment_free (seg2);
      
      /* we've now prepended as1's segment chain to as2, merging
       * the inbetween AS_SEQUENCE of seg2 in the process 
       */
      aspath_str_update (as2);
      return as2;
    }
  else
    {
      /* AS_SET merge code is needed at here. */
      return aspath_merge (as1, as2);
    }
  /* XXX: Ermmm, what if as1 has multiple segments?? */
  
  /* Not reached */
}

/* Iterate over AS_PATH segments and wipe all occurences of the
 * listed AS numbers. Hence some segments may lose some or even
 * all data on the way, the operation is implemented as a smarter
 * version of aspath_dup(), which allocates memory to hold the new
 * data, not the original. The new AS path is returned.
 */
struct aspath *
aspath_filter_exclude (struct aspath * source, struct aspath * exclude_list)
{
  struct assegment * srcseg, * exclseg, * lastseg;
  struct aspath * newpath;

  newpath = aspath_new();
  lastseg = NULL;

  for (srcseg = source->segments; srcseg; srcseg = srcseg->next)
  {
    unsigned i, y, newlen = 0, done = 0, skip_as;
    struct assegment * newseg;

    /* Find out, how much ASns are we going to pick from this segment.
     * We can't perform filtering right inline, because the size of
     * the new segment isn't known at the moment yet.
     */
    for (i = 0; i < srcseg->length; i++)
    {
      skip_as = 0;
      for (exclseg = exclude_list->segments; exclseg && !skip_as; exclseg = exclseg->next)
        for (y = 0; y < exclseg->length; y++)
          if (srcseg->as[i] == exclseg->as[y])
          {
            skip_as = 1;
            // There's no sense in testing the rest of exclusion list, bail out.
            break;
          }
      if (!skip_as)
        newlen++;
    }
    /* newlen is now the number of ASns to copy */
    if (!newlen)
      continue;

    /* Actual copying. Allocate memory and iterate once more, performing filtering. */
    newseg = assegment_new (srcseg->type, newlen);
    for (i = 0; i < srcseg->length; i++)
    {
      skip_as = 0;
      for (exclseg = exclude_list->segments; exclseg && !skip_as; exclseg = exclseg->next)
        for (y = 0; y < exclseg->length; y++)
          if (srcseg->as[i] == exclseg->as[y])
          {
            skip_as = 1;
            break;
          }
      if (skip_as)
        continue;
      newseg->as[done++] = srcseg->as[i];
    }
    /* At his point newlen must be equal to done, and both must be positive. Append
     * the filtered segment to the gross result. */
    if (!lastseg)
      newpath->segments = newseg;
    else
      lastseg->next = newseg;
    lastseg = newseg;
  }
  aspath_str_update (newpath);
  /* We are happy returning even an empty AS_PATH, because the administrator
   * might expect this very behaviour. There's a mean to avoid this, if necessary,
   * by having a match rule against certain AS_PATH regexps in the route-map index.
   */
  aspath_free (source);
  return newpath;
}

/* Add specified AS to the leftmost of aspath. */
static struct aspath *
aspath_add_one_as (struct aspath *aspath, as_t asno, u_char type)
{
  struct assegment *assegment = aspath->segments;

  /* In case of empty aspath. */
  if (assegment == NULL || assegment->length == 0)
    {
      aspath->segments = assegment_new (type, 1);
      aspath->segments->as[0] = asno;
      
      if (assegment)
	assegment_free (assegment);

      return aspath;
    }

  if (assegment->type == type)
    aspath->segments = assegment_prepend_asns (aspath->segments, asno, 1);
  else 
    {
      /* create new segment
       * push it onto head of aspath's segment chain 
       */
      struct assegment *newsegment;
      
      newsegment = assegment_new (type, 1);
      newsegment->as[0] = asno;
      
      newsegment->next = assegment;
      aspath->segments = newsegment;
    }

  return aspath;
}

/* Add specified AS to the leftmost of aspath. */
struct aspath *
aspath_add_seq (struct aspath *aspath, as_t asno)
{
  return aspath_add_one_as (aspath, asno, AS_SEQUENCE);
}

/* Compare leftmost AS value for MED check.  If as1's leftmost AS and
   as2's leftmost AS is same return 1. */
int
aspath_cmp_left (const struct aspath *aspath1, const struct aspath *aspath2)
{
  const struct assegment *seg1 = NULL;
  const struct assegment *seg2 = NULL;

  if (!(aspath1 && aspath2))
    return 0;

  seg1 = aspath1->segments;
  seg2 = aspath2->segments;

  /* find first non-confed segments for each */
  while (seg1 && ((seg1->type == AS_CONFED_SEQUENCE)
		  || (seg1->type == AS_CONFED_SET)))
    seg1 = seg1->next;

  while (seg2 && ((seg2->type == AS_CONFED_SEQUENCE)
		  || (seg2->type == AS_CONFED_SET)))
    seg2 = seg2->next;

  /* Check as1's */
  if (!(seg1 && seg2
	&& (seg1->type == AS_SEQUENCE) && (seg2->type == AS_SEQUENCE)))
    return 0;
  
  if (seg1->as[0] == seg2->as[0])
    return 1;

  return 0;
}

/* Truncate an aspath after a number of hops, and put the hops remaining
 * at the front of another aspath.  Needed for AS4 compat.
 *
 * Returned aspath is a /new/ aspath, which should either by free'd or
 * interned by the caller, as desired.
 */
struct aspath *
aspath_reconcile_as4 ( struct aspath *aspath, struct aspath *as4path)
{
  struct assegment *seg, *newseg, *prevseg = NULL;
  struct aspath *newpath = NULL, *mergedpath;
  int hops, cpasns = 0;
  
  if (!aspath)
    return NULL;
  
  seg = aspath->segments;
  
  /* CONFEDs should get reconciled too.. */
  hops = (aspath_count_hops (aspath) + aspath_count_confeds (aspath))
         - aspath_count_hops (as4path);
  
  if (hops < 0)
    {
      if (BGP_DEBUG (as4, AS4))
        zlog_warn ("[AS4] Fewer hops in AS_PATH than NEW_AS_PATH");
      /* Something's gone wrong. The RFC says we should now ignore AS4_PATH,
       * which is daft behaviour - it contains vital loop-detection
       * information which must have been removed from AS_PATH.
       */
       hops = aspath_count_hops (aspath);
    }
  
  if (!hops)
   return aspath_dup (as4path);
  
  if ( BGP_DEBUG(as4, AS4))
    zlog_debug("[AS4] got AS_PATH %s and AS4_PATH %s synthesizing now",
               aspath->str, as4path->str);

  while (seg && hops > 0)
    {
      switch (seg->type)
        {
          case AS_SET:
          case AS_CONFED_SET:
            hops--;
            cpasns = seg->length;
            break;
          case AS_CONFED_SEQUENCE:
	    /* Should never split a confed-sequence, if hop-count
	     * suggests we must then something's gone wrong somewhere.
	     *
	     * Most important goal is to preserve AS_PATHs prime function
	     * as loop-detector, so we fudge the numbers so that the entire
	     * confed-sequence is merged in.
	     */
	    if (hops < seg->length)
	      {
	        if (BGP_DEBUG (as4, AS4))
	          zlog_debug ("[AS4] AS4PATHmangle: AS_CONFED_SEQUENCE falls"
	                      " across 2/4 ASN boundary somewhere, broken..");
	        hops = seg->length;
	      }
	  case AS_SEQUENCE:
	    cpasns = MIN(seg->length, hops);
	    hops -= seg->length;
	}
      
      assert (cpasns <= seg->length);
      
      newseg = assegment_new (seg->type, 0);
      newseg = assegment_append_asns (newseg, seg->as, cpasns);

      if (!newpath)
        {
          newpath = aspath_new ();
          newpath->segments = newseg;
        }
      else
        prevseg->next = newseg;

      prevseg = newseg;
      seg = seg->next;
    }
    
  /* We may be able to join some segments here, and we must
   * do this because... we want normalised aspaths in out hash
   * and we do not want to stumble in aspath_put.
   */
  mergedpath = aspath_merge (newpath, aspath_dup(as4path));
  aspath_free (newpath);
  mergedpath->segments = assegment_normalise (mergedpath->segments);
  aspath_str_update (mergedpath);
  
  if ( BGP_DEBUG(as4, AS4))
    zlog_debug ("[AS4] result of synthesizing is %s",
                mergedpath->str);
  
  return mergedpath;
}

/* Compare leftmost AS value for MED check.  If as1's leftmost AS and
   as2's leftmost AS is same return 1. (confederation as-path
   only).  */
int
aspath_cmp_left_confed (const struct aspath *aspath1, const struct aspath *aspath2)
{
  if (! (aspath1 && aspath2) )
    return 0;
  
  if ( !(aspath1->segments && aspath2->segments) )
    return 0;
  
  if ( (aspath1->segments->type != AS_CONFED_SEQUENCE)
      || (aspath2->segments->type != AS_CONFED_SEQUENCE) )
    return 0;
  
  if (aspath1->segments->as[0] == aspath2->segments->as[0])
    return 1;

  return 0;
}

/* Delete all leading AS_CONFED_SEQUENCE/SET segments from aspath.
 * See RFC3065, 6.1 c1 */
struct aspath *
aspath_delete_confed_seq (struct aspath *aspath)
{
  struct assegment *seg;

  if (!(aspath && aspath->segments))
    return aspath;

  seg = aspath->segments;
  
  /* "if the first path segment of the AS_PATH is 
   *  of type AS_CONFED_SEQUENCE,"
   */
  if (aspath->segments->type != AS_CONFED_SEQUENCE)
    return aspath;

  /* "... that segment and any immediately following segments 
   *  of the type AS_CONFED_SET or AS_CONFED_SEQUENCE are removed 
   *  from the AS_PATH attribute,"
   */
  while (seg && 
         (seg->type == AS_CONFED_SEQUENCE || seg->type == AS_CONFED_SET))
    {
      aspath->segments = seg->next;
      assegment_free (seg);
      seg = aspath->segments;
    }
  aspath_str_update (aspath);
  return aspath;
}

/* Add new AS number to the leftmost part of the aspath as
   AS_CONFED_SEQUENCE.  */
struct aspath*
aspath_add_confed_seq (struct aspath *aspath, as_t asno)
{
  return aspath_add_one_as (aspath, asno, AS_CONFED_SEQUENCE);
}

/* Add new as value to as path structure. */
static void
aspath_as_add (struct aspath *as, as_t asno)
{
  struct assegment *seg = as->segments;

  if (!seg)
    return;
  
  /* Last segment search procedure. */
  while (seg->next)
    seg = seg->next;

  assegment_append_asns (seg, &asno, 1);
}

/* Add new as segment to the as path. */
static void
aspath_segment_add (struct aspath *as, int type)
{
  struct assegment *seg = as->segments;
  struct assegment *new = assegment_new (type, 0);

  if (seg)
    {
      while (seg->next)
	seg = seg->next;
      seg->next = new;
    }
  else
    as->segments = new;
}

struct aspath *
aspath_empty (void)
{
  return aspath_parse (NULL, 0, 1, 0); /* 32Bit ;-) not AS4_PATH */
}

struct aspath *
aspath_empty_get (void)
{
  struct aspath *aspath;

  aspath = aspath_new ();
  aspath->str = aspath_make_str_count (aspath);
  return aspath;
}

unsigned long
aspath_count (void)
{
  return ashash->count;
}     

/* 
   Theoretically, one as path can have:

   One BGP packet size should be less than 4096.
   One BGP attribute size should be less than 4096 - BGP header size.
   One BGP aspath size should be less than 4096 - BGP header size -
       BGP mandantry attribute size.
*/

/* AS path string lexical token enum. */
enum as_token
{
  as_token_asval,
  as_token_set_start,
  as_token_set_end,
  as_token_confed_seq_start,
  as_token_confed_seq_end,
  as_token_confed_set_start,
  as_token_confed_set_end,
  as_token_unknown
};

/* Return next token and point for string parse. */
static const char *
aspath_gettoken (const char *buf, enum as_token *token, u_long *asno)
{
  const char *p = buf;

  /* Skip seperators (space for sequences, ',' for sets). */
  while (isspace ((int) *p) || *p == ',')
    p++;

  /* Check the end of the string and type specify characters
     (e.g. {}()). */
  switch (*p)
    {
    case '\0':
      return NULL;
    case '{':
      *token = as_token_set_start;
      p++;
      return p;
    case '}':
      *token = as_token_set_end;
      p++;
      return p;
    case '(':
      *token = as_token_confed_seq_start;
      p++;
      return p;
    case ')':
      *token = as_token_confed_seq_end;
      p++;
      return p;
    case '[':
      *token = as_token_confed_set_start;
      p++;
      return p;
    case ']':
      *token = as_token_confed_set_end;
      p++;
      return p;
    }

  /* Check actual AS value. */
  if (isdigit ((int) *p)) 
    {
      as_t asval;
      
      *token = as_token_asval;
      asval = (*p - '0');
      p++;
      
      while (isdigit ((int) *p)) 
        {
          asval *= 10;
          asval += (*p - '0');
          p++;
        }
      *asno = asval;
      return p;
    }
  
  /* There is no match then return unknown token. */
  *token = as_token_unknown;
  return  p++;
}

struct aspath *
aspath_str2aspath (const char *str)
{
  enum as_token token = as_token_unknown;
  u_short as_type;
  u_long asno = 0;
  struct aspath *aspath;
  int needtype;

  aspath = aspath_new ();

  /* We start default type as AS_SEQUENCE. */
  as_type = AS_SEQUENCE;
  needtype = 1;

  while ((str = aspath_gettoken (str, &token, &asno)) != NULL)
    {
      switch (token)
	{
	case as_token_asval:
	  if (needtype)
	    {
	      aspath_segment_add (aspath, as_type);
	      needtype = 0;
	    }
	  aspath_as_add (aspath, asno);
	  break;
	case as_token_set_start:
	  as_type = AS_SET;
	  aspath_segment_add (aspath, as_type);
	  needtype = 0;
	  break;
	case as_token_set_end:
	  as_type = AS_SEQUENCE;
	  needtype = 1;
	  break;
	case as_token_confed_seq_start:
	  as_type = AS_CONFED_SEQUENCE;
	  aspath_segment_add (aspath, as_type);
	  needtype = 0;
	  break;
	case as_token_confed_seq_end:
	  as_type = AS_SEQUENCE;
	  needtype = 1;
	  break;
	case as_token_confed_set_start:
	  as_type = AS_CONFED_SET;
	  aspath_segment_add (aspath, as_type);
	  needtype = 0;
	  break;
	case as_token_confed_set_end:
	  as_type = AS_SEQUENCE;
	  needtype = 1;
	  break;
	case as_token_unknown:
	default:
	  aspath_free (aspath);
	  return NULL;
	}
    }

  aspath->str = aspath_make_str_count (aspath);

  return aspath;
}

/* Make hash value by raw aspath data. */
unsigned int
aspath_key_make (void *p)
{
  struct aspath * aspath = (struct aspath *) p;
  unsigned int key = 0;

  if (!aspath->str)
    aspath_str_update (aspath);
  
  key = jhash (aspath->str, strlen(aspath->str), 2334325);

  return key;
}

/* If two aspath have same value then return 1 else return 0 */
static int
aspath_cmp (const void *arg1, const void *arg2)
{
  const struct assegment *seg1 = ((const struct aspath *)arg1)->segments;
  const struct assegment *seg2 = ((const struct aspath *)arg2)->segments;
  
  while (seg1 || seg2)
    {
      int i;
      if ((!seg1 && seg2) || (seg1 && !seg2))
	return 0;
      if (seg1->type != seg2->type)
        return 0;      
      if (seg1->length != seg2->length)
        return 0;
      for (i = 0; i < seg1->length; i++)
        if (seg1->as[i] != seg2->as[i])
          return 0;
      seg1 = seg1->next;
      seg2 = seg2->next;
    }
  return 1;
}

/* AS path hash initialize. */
void
aspath_init (void)
{
  ashash = hash_create_size (32767, aspath_key_make, aspath_cmp);
}

void
aspath_finish (void)
{
  hash_free (ashash);
  ashash = NULL;
  
  if (snmp_stream)
    stream_free (snmp_stream);
}

/* return and as path value */
const char *
aspath_print (struct aspath *as)
{
  return (as ? as->str : NULL);
}

/* Printing functions */
/* Feed the AS_PATH to the vty; the suffix string follows it only in case
 * AS_PATH wasn't empty.
 */
void
aspath_print_vty (struct vty *vty, const char *format, struct aspath *as, const char * suffix)
{
  assert (format);
  vty_out (vty, format, as->str);
  if (strlen (as->str) && strlen (suffix))
    vty_out (vty, "%s", suffix);
}

static void
aspath_show_all_iterator (struct hash_backet *backet, struct vty *vty)
{
  struct aspath *as;

  as = (struct aspath *) backet->data;

  vty_out (vty, "[%p:%u] (%ld) ", backet, backet->key, as->refcnt);
  vty_out (vty, "%s%s", as->str, VTY_NEWLINE);
}

/* Print all aspath and hash information.  This function is used from
   `show ip bgp paths' command. */
void
aspath_print_all_vty (struct vty *vty)
{
  hash_iterate (ashash, 
		(void (*) (struct hash_backet *, void *))
		aspath_show_all_iterator,
		vty);
}