bgpd: enhance reception of bgp ext. community default gateway

[mirror_frr.git] / bgpd / bgp_ecommunity.c

/* BGP Extended Communities Attribute
   Copyright (C) 2000 Kunihiro Ishiguro <kunihiro@zebra.org>

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 "prefix.h"
#include "command.h"
#include "queue.h"
#include "filter.h"

#include "bgpd/bgpd.h"
#include "bgpd/bgp_ecommunity.h"
#include "bgpd/bgp_lcommunity.h"
#include "bgpd/bgp_aspath.h"

/* Hash of community attribute. */
static struct hash *ecomhash;

/* Allocate a new ecommunities.  */
struct ecommunity *
ecommunity_new (void)
{
  return (struct ecommunity *) XCALLOC (MTYPE_ECOMMUNITY,
					sizeof (struct ecommunity));
}

/* Allocate ecommunities.  */
void
ecommunity_free (struct ecommunity **ecom)
{
  if ((*ecom)->val)
    XFREE (MTYPE_ECOMMUNITY_VAL, (*ecom)->val);
  if ((*ecom)->str)
    XFREE (MTYPE_ECOMMUNITY_STR, (*ecom)->str);
  XFREE (MTYPE_ECOMMUNITY, *ecom);
  ecom = NULL;
}

static void 
ecommunity_hash_free (struct ecommunity *ecom)
{
  ecommunity_free(&ecom);
}


/* Add a new Extended Communities value to Extended Communities
   Attribute structure.  When the value is already exists in the
   structure, we don't add the value.  Newly added value is sorted by
   numerical order.  When the value is added to the structure return 1
   else return 0.  */
int
ecommunity_add_val (struct ecommunity *ecom, struct ecommunity_val *eval)
{
  u_int8_t *p;
  int ret;
  int c;

  /* When this is fist value, just add it.  */
  if (ecom->val == NULL)
    {
      ecom->size++;
      ecom->val = XMALLOC (MTYPE_ECOMMUNITY_VAL, ecom_length (ecom));
      memcpy (ecom->val, eval->val, ECOMMUNITY_SIZE);
      return 1;
    }

  /* If the value already exists in the structure return 0.  */
  c = 0;
  for (p = ecom->val; c < ecom->size; p += ECOMMUNITY_SIZE, c++)
    {
      ret = memcmp (p, eval->val, ECOMMUNITY_SIZE);
      if (ret == 0)
        return 0;
      if (ret > 0)
        break;
    }

  /* Add the value to the structure with numerical sorting.  */
  ecom->size++;
  ecom->val = XREALLOC (MTYPE_ECOMMUNITY_VAL, ecom->val, ecom_length (ecom));

  memmove (ecom->val + (c + 1) * ECOMMUNITY_SIZE,
	   ecom->val + c * ECOMMUNITY_SIZE,
	   (ecom->size - 1 - c) * ECOMMUNITY_SIZE);
  memcpy (ecom->val + c * ECOMMUNITY_SIZE, eval->val, ECOMMUNITY_SIZE);

  return 1;
}

/* This function takes pointer to Extended Communites strucutre then
   create a new Extended Communities structure by uniq and sort each
   Extended Communities value.  */
struct ecommunity *
ecommunity_uniq_sort (struct ecommunity *ecom)
{
  int i;
  struct ecommunity *new;
  struct ecommunity_val *eval;
  
  if (! ecom)
    return NULL;
  
  new = ecommunity_new ();
  
  for (i = 0; i < ecom->size; i++)
    {
      eval = (struct ecommunity_val *) (ecom->val + (i * ECOMMUNITY_SIZE));
      ecommunity_add_val (new, eval);
    }
  return new;
}

/* Parse Extended Communites Attribute in BGP packet.  */
struct ecommunity *
ecommunity_parse (u_int8_t *pnt, u_short length)
{
  struct ecommunity tmp;
  struct ecommunity *new;

  /* Length check.  */
  if (length % ECOMMUNITY_SIZE)
    return NULL;

  /* Prepare tmporary structure for making a new Extended Communities
     Attribute.  */
  tmp.size = length / ECOMMUNITY_SIZE;
  tmp.val = pnt;

  /* Create a new Extended Communities Attribute by uniq and sort each
     Extended Communities value  */
  new = ecommunity_uniq_sort (&tmp);

  return ecommunity_intern (new);
}

/* Duplicate the Extended Communities Attribute structure.  */
struct ecommunity *
ecommunity_dup (struct ecommunity *ecom)
{
  struct ecommunity *new;

  new = XCALLOC (MTYPE_ECOMMUNITY, sizeof (struct ecommunity));
  new->size = ecom->size;
  if (new->size)
    {
      new->val = XMALLOC (MTYPE_ECOMMUNITY_VAL, ecom->size * ECOMMUNITY_SIZE);
      memcpy (new->val, ecom->val, ecom->size * ECOMMUNITY_SIZE);
    }
  else
    new->val = NULL;
  return new;
}

/* Retrun string representation of communities attribute. */
char *
ecommunity_str (struct ecommunity *ecom)
{
  if (! ecom->str)
    ecom->str = ecommunity_ecom2str (ecom, ECOMMUNITY_FORMAT_DISPLAY);
  return ecom->str;
}

/* Merge two Extended Communities Attribute structure.  */
struct ecommunity *
ecommunity_merge (struct ecommunity *ecom1, struct ecommunity *ecom2)
{
  if (ecom1->val)
    ecom1->val = XREALLOC (MTYPE_ECOMMUNITY_VAL, ecom1->val, 
			   (ecom1->size + ecom2->size) * ECOMMUNITY_SIZE);
  else
    ecom1->val = XMALLOC (MTYPE_ECOMMUNITY_VAL,
			  (ecom1->size + ecom2->size) * ECOMMUNITY_SIZE);

  memcpy (ecom1->val + (ecom1->size * ECOMMUNITY_SIZE),
	  ecom2->val, ecom2->size * ECOMMUNITY_SIZE);
  ecom1->size += ecom2->size;

  return ecom1;
}

/* Intern Extended Communities Attribute.  */
struct ecommunity *
ecommunity_intern (struct ecommunity *ecom)
{
  struct ecommunity *find;

  assert (ecom->refcnt == 0);

  find = (struct ecommunity *) hash_get (ecomhash, ecom, hash_alloc_intern);

  if (find != ecom)
    ecommunity_free (&ecom);

  find->refcnt++;

  if (! find->str)
    find->str = ecommunity_ecom2str (find, ECOMMUNITY_FORMAT_DISPLAY);

  return find;
}

/* Unintern Extended Communities Attribute.  */
void
ecommunity_unintern (struct ecommunity **ecom)
{
  struct ecommunity *ret;

  if ((*ecom)->refcnt)
    (*ecom)->refcnt--;
    
  /* Pull off from hash.  */
  if ((*ecom)->refcnt == 0)
    {
      /* Extended community must be in the hash.  */
      ret = (struct ecommunity *) hash_release (ecomhash, *ecom);
      assert (ret != NULL);

      ecommunity_free (ecom);
    }
}

/* Utinity function to make hash key.  */
unsigned int
ecommunity_hash_make (void *arg)
{
  const struct ecommunity *ecom = arg;
  int size = ecom->size * ECOMMUNITY_SIZE;
  u_int8_t *pnt = ecom->val;
  unsigned int key = 0;
  int c;

  for (c = 0; c < size; c += ECOMMUNITY_SIZE)
    {
      key += pnt[c];
      key += pnt[c + 1];
      key += pnt[c + 2];
      key += pnt[c + 3];
      key += pnt[c + 4];
      key += pnt[c + 5];
      key += pnt[c + 6];
      key += pnt[c + 7];
    }

  return key;
}

/* Compare two Extended Communities Attribute structure.  */
int
ecommunity_cmp (const void *arg1, const void *arg2)
{
  const struct ecommunity *ecom1 = arg1;
  const struct ecommunity *ecom2 = arg2;

  if (ecom1 == NULL && ecom2 == NULL)
    return 1;

  if (ecom1 == NULL || ecom2 == NULL)
    return 0;
  
  return (ecom1->size == ecom2->size
	  && memcmp (ecom1->val, ecom2->val, ecom1->size * ECOMMUNITY_SIZE) == 0);
}

/* Initialize Extended Comminities related hash. */
void
ecommunity_init (void)
{
  ecomhash = hash_create (ecommunity_hash_make, ecommunity_cmp);
}

void
ecommunity_finish (void)
{
  hash_clean (ecomhash, (void (*)(void *))ecommunity_hash_free);
  hash_free (ecomhash);
  ecomhash = NULL;
}

/* Extended Communities token enum. */
enum ecommunity_token
{
  ecommunity_token_unknown = 0,
  ecommunity_token_rt,
  ecommunity_token_soo,
  ecommunity_token_val,
};

/* Get next Extended Communities token from the string. */
static const char *
ecommunity_gettoken (const char *str, struct ecommunity_val *eval,
		     enum ecommunity_token *token)
{
  int ret;
  int dot = 0;
  int digit = 0;
  int separator = 0;
  const char *p = str;
  char *endptr;
  struct in_addr ip;
  as_t as = 0;
  u_int32_t val = 0;
  char buf[INET_ADDRSTRLEN + 1];

  /* Skip white space. */
  while (isspace ((int) *p))
    {
      p++;
      str++;
    }

  /* Check the end of the line. */
  if (*p == '\0')
    return NULL;

  /* "rt" and "soo" keyword parse. */
  if (! isdigit ((int) *p)) 
    {
      /* "rt" match check.  */
      if (tolower ((int) *p) == 'r')
	{
	  p++;
 	  if (tolower ((int) *p) == 't')
	    {
	      p++;
	      *token = ecommunity_token_rt;
	      return p;
	    }
	  if (isspace ((int) *p) || *p == '\0')
	    {
	      *token = ecommunity_token_rt;
	      return p;
	    }
	  goto error;
	}
      /* "soo" match check.  */
      else if (tolower ((int) *p) == 's')
	{
	  p++;
 	  if (tolower ((int) *p) == 'o')
	    {
	      p++;
	      if (tolower ((int) *p) == 'o')
		{
		  p++;
		  *token = ecommunity_token_soo;
		  return p;
		}
	      if (isspace ((int) *p) || *p == '\0')
		{
		  *token = ecommunity_token_soo;
		  return p;
		}
	      goto error;
	    }
	  if (isspace ((int) *p) || *p == '\0')
	    {
	      *token = ecommunity_token_soo;
	      return p;
	    }
	  goto error;
	}
      goto error;
    }
  
  /* What a mess, there are several possibilities:
   *
   * a) A.B.C.D:MN
   * b) EF:OPQR
   * c) GHJK:MN
   *
   * A.B.C.D: Four Byte IP
   * EF:      Two byte ASN
   * GHJK:    Four-byte ASN
   * MN:      Two byte value
   * OPQR:    Four byte value
   *
   */
  while (isdigit ((int) *p) || *p == ':' || *p == '.') 
    {
      if (*p == ':')
	{
	  if (separator)
	    goto error;

	  separator = 1;
	  digit = 0;
	  
	  if ((p - str) > INET_ADDRSTRLEN)
	    goto error;
          memset (buf, 0, INET_ADDRSTRLEN + 1);
          memcpy (buf, str, p - str);
          
	  if (dot)
	    {
	      /* Parsing A.B.C.D in:
               * A.B.C.D:MN
               */
	      ret = inet_aton (buf, &ip);
	      if (ret == 0)
	        goto error;
	    }
          else
            {
              /* ASN */
              as = strtoul (buf, &endptr, 10);
              if (*endptr != '\0' || as == BGP_AS4_MAX)
                goto error;
            }
	}
      else if (*p == '.')
	{
	  if (separator)
	    goto error;
	  dot++;
	  if (dot > 4)
	    goto error;
	}
      else
	{
	  digit = 1;
	  
	  /* We're past the IP/ASN part */
	  if (separator)
	    {
	      val *= 10;
	      val += (*p - '0');
            }
	}
      p++;
    }

  /* Low digit part must be there. */
  if (!digit || !separator)
    goto error;

  /* Encode result into routing distinguisher.  */
  if (dot)
    {
      if (val > UINT16_MAX)
        goto error;
      
      eval->val[0] = ECOMMUNITY_ENCODE_IP;
      eval->val[1] = 0;
      memcpy (&eval->val[2], &ip, sizeof (struct in_addr));
      eval->val[6] = (val >> 8) & 0xff;
      eval->val[7] = val & 0xff;
    }
  else if (as > BGP_AS_MAX)
    {
      if (val > UINT16_MAX)
        goto error;
      
      eval->val[0] = ECOMMUNITY_ENCODE_AS4;
      eval->val[1] = 0;
      eval->val[2] = (as >>24) & 0xff;
      eval->val[3] = (as >>16) & 0xff;
      eval->val[4] = (as >>8) & 0xff;
      eval->val[5] =  as & 0xff;
      eval->val[6] = (val >> 8) & 0xff;
      eval->val[7] = val & 0xff;
    }
  else
    {
      eval->val[0] = ECOMMUNITY_ENCODE_AS;
      eval->val[1] = 0;
      
      eval->val[2] = (as >>8) & 0xff;
      eval->val[3] = as & 0xff;
      eval->val[4] = (val >>24) & 0xff;
      eval->val[5] = (val >>16) & 0xff;
      eval->val[6] = (val >>8) & 0xff;
      eval->val[7] = val & 0xff;
    }
  *token = ecommunity_token_val;
  return p;

 error:
  *token = ecommunity_token_unknown;
  return p;
}

/* Convert string to extended community attribute. 

   When type is already known, please specify both str and type.  str
   should not include keyword such as "rt" and "soo".  Type is
   ECOMMUNITY_ROUTE_TARGET or ECOMMUNITY_SITE_ORIGIN.
   keyword_included should be zero.

   For example route-map's "set extcommunity" command case:

   "rt 100:1 100:2 100:3"        -> str = "100:1 100:2 100:3"
                                    type = ECOMMUNITY_ROUTE_TARGET
                                    keyword_included = 0

   "soo 100:1"                   -> str = "100:1"
                                    type = ECOMMUNITY_SITE_ORIGIN
                                    keyword_included = 0

   When string includes keyword for each extended community value.
   Please specify keyword_included as non-zero value.

   For example standard extcommunity-list case:

   "rt 100:1 rt 100:2 soo 100:1" -> str = "rt 100:1 rt 100:2 soo 100:1"
                                    type = 0
                                    keyword_include = 1
*/
struct ecommunity *
ecommunity_str2com (const char *str, int type, int keyword_included)
{
  struct ecommunity *ecom = NULL;
  enum ecommunity_token token = ecommunity_token_unknown;
  struct ecommunity_val eval;
  int keyword = 0;

  while ((str = ecommunity_gettoken (str, &eval, &token)))
    {
      switch (token)
	{
	case ecommunity_token_rt:
	case ecommunity_token_soo:
	  if (! keyword_included || keyword)
	    {
	      if (ecom)
		ecommunity_free (&ecom);
	      return NULL;
	    }
	  keyword = 1;

	  if (token == ecommunity_token_rt)
	    {
	      type = ECOMMUNITY_ROUTE_TARGET;
	    }
	  if (token == ecommunity_token_soo)
	    {
	      type = ECOMMUNITY_SITE_ORIGIN;
	    }
	  break;
	case ecommunity_token_val:
	  if (keyword_included)
	    {
	      if (! keyword)
		{
		  if (ecom)
		    ecommunity_free (&ecom);
		  return NULL;
		}
	      keyword = 0;
	    }
	  if (ecom == NULL)
	    ecom = ecommunity_new ();
	  eval.val[1] = type;
	  ecommunity_add_val (ecom, &eval);
	  break;
	case ecommunity_token_unknown:
	default:
	  if (ecom)
	    ecommunity_free (&ecom);
	  return NULL;
	}
    }
  return ecom;
}

/* Convert extended community attribute to string.  

   Due to historical reason of industry standard implementation, there
   are three types of format.

   route-map set extcommunity format
        "rt 100:1 100:2"
        "soo 100:3"

   extcommunity-list
        "rt 100:1 rt 100:2 soo 100:3"

   "show [ip] bgp" and extcommunity-list regular expression matching
        "RT:100:1 RT:100:2 SoO:100:3"

   For each formath please use below definition for format:

   ECOMMUNITY_FORMAT_ROUTE_MAP
   ECOMMUNITY_FORMAT_COMMUNITY_LIST
   ECOMMUNITY_FORMAT_DISPLAY
*/
char *
ecommunity_ecom2str (struct ecommunity *ecom, int format)
{
  int i;
  u_int8_t *pnt;
  int encode = 0;
  int type = 0;
#define ECOMMUNITY_STR_DEFAULT_LEN  27
  int str_size;
  int str_pnt;
  char *str_buf;
  const char *prefix;
  int len = 0;
  int first = 1;

  /* For parse Extended Community attribute tupple. */
  struct ecommunity_as
  {
    as_t as;
    u_int32_t val;
  } eas;

  struct ecommunity_ip
  {
    struct in_addr ip;
    u_int16_t val;
  } eip;

  if (ecom->size == 0)
    {
      str_buf = XMALLOC (MTYPE_ECOMMUNITY_STR, 1);
      str_buf[0] = '\0';
      return str_buf;
    }

  /* Prepare buffer.  */
  str_buf = XMALLOC (MTYPE_ECOMMUNITY_STR, ECOMMUNITY_STR_DEFAULT_LEN + 1);
  str_size = ECOMMUNITY_STR_DEFAULT_LEN + 1;
  str_pnt = 0;

  for (i = 0; i < ecom->size; i++)
    {
      /* Make it sure size is enough.  */
      while (str_pnt + ECOMMUNITY_STR_DEFAULT_LEN >= str_size)
	{
	  str_size *= 2;
	  str_buf = XREALLOC (MTYPE_ECOMMUNITY_STR, str_buf, str_size);
	}

      /* Space between each value.  */
      if (! first)
	str_buf[str_pnt++] = ' ';

      pnt = ecom->val + (i * 8);

      /* High-order octet of type. */
      encode = *pnt++;

      switch (encode)
        {
        case ECOMMUNITY_ENCODE_AS:
        case ECOMMUNITY_ENCODE_IP:
        case ECOMMUNITY_ENCODE_AS4:
          break;

        case ECOMMUNITY_ENCODE_OPAQUE:
          if (*pnt == ECOMMUNITY_OPAQUE_SUBTYPE_ENCAP)
            {
              uint16_t tunneltype;
              memcpy (&tunneltype, pnt + 5, 2);
              tunneltype = ntohs(tunneltype);
              len = sprintf (str_buf + str_pnt, "ET:%d", tunneltype);
              str_pnt += len;
              first = 0;
              continue;
            }
            /* fall through */

        default:
          len = sprintf (str_buf + str_pnt, "?");
          str_pnt += len;
          first = 0;
          continue;
        }

      /* Low-order octet of type. */
      type = *pnt++;
      if (type !=  ECOMMUNITY_ROUTE_TARGET && type != ECOMMUNITY_SITE_ORIGIN)
	{
	  len = sprintf (str_buf + str_pnt, "?");
	  str_pnt += len;
	  first = 0;
	  continue;
	}

      switch (format)
	{
	case ECOMMUNITY_FORMAT_COMMUNITY_LIST:
	  prefix = (type == ECOMMUNITY_ROUTE_TARGET ? "rt " : "soo ");
	  break;
	case ECOMMUNITY_FORMAT_DISPLAY:
	  prefix = (type == ECOMMUNITY_ROUTE_TARGET ? "RT:" : "SoO:");
	  break;
	case ECOMMUNITY_FORMAT_ROUTE_MAP:
	  prefix = "";
	  break;
	default:
	  prefix = "";
	  break;
	}

      /* Put string into buffer.  */
      if (encode == ECOMMUNITY_ENCODE_AS4)
	{
	  eas.as = (*pnt++ << 24);
	  eas.as |= (*pnt++ << 16);
	  eas.as |= (*pnt++ << 8);
	  eas.as |= (*pnt++);

	  eas.val = (*pnt++ << 8);
	  eas.val |= (*pnt++);

	  len = sprintf( str_buf + str_pnt, "%s%u:%u", prefix,
                        eas.as, eas.val );
	  str_pnt += len;
	  first = 0;
	}
      if (encode == ECOMMUNITY_ENCODE_AS)
	{
	  eas.as = (*pnt++ << 8);
	  eas.as |= (*pnt++);

	  eas.val = (*pnt++ << 24);
	  eas.val |= (*pnt++ << 16);
	  eas.val |= (*pnt++ << 8);
	  eas.val |= (*pnt++);

	  len = sprintf (str_buf + str_pnt, "%s%u:%u", prefix,
			 eas.as, eas.val);
	  str_pnt += len;
	  first = 0;
	}
      else if (encode == ECOMMUNITY_ENCODE_IP)
	{
	  memcpy (&eip.ip, pnt, 4);
	  pnt += 4;
	  eip.val = (*pnt++ << 8);
	  eip.val |= (*pnt++);

	  len = sprintf (str_buf + str_pnt, "%s%s:%u", prefix,
			 inet_ntoa (eip.ip), eip.val);
	  str_pnt += len;
	  first = 0;
	}
    }
  return str_buf;
}

int
ecommunity_match (const struct ecommunity *ecom1, 
                  const struct ecommunity *ecom2)
{
  int i = 0;
  int j = 0;

  if (ecom1 == NULL && ecom2 == NULL)
    return 1;

  if (ecom1 == NULL || ecom2 == NULL)
    return 0;

  if (ecom1->size < ecom2->size)
    return 0;

  /* Every community on com2 needs to be on com1 for this to match */
  while (i < ecom1->size && j < ecom2->size)
    {
      if (memcmp (ecom1->val + i * ECOMMUNITY_SIZE,
                  ecom2->val + j * ECOMMUNITY_SIZE,
                  ECOMMUNITY_SIZE) == 0)
        j++;
      i++;
    }

  if (j == ecom2->size)
    return 1;
  else
    return 0;
}

/* return first occurence of type */
extern struct ecommunity_val *ecommunity_lookup (const struct ecommunity *ecom, uint8_t type, uint8_t subtype)
{
  u_int8_t *p;
  int c;
  struct ecommunity_val *ecom_val;

  /* If the value already exists in the structure return 0.  */
  c = 0;
  for (p = ecom->val; c < ecom->size; p += ECOMMUNITY_SIZE, c++)
    {
      if(p == NULL)
        {
          continue;
        }
      if(p[0] == type && p[1] == subtype)
        return (struct ecommunity_val *)p;
    }
  return NULL;
}

/* remove ext. community matching type and subtype
 * return 1 on success ( removed ), 0 otherwise (not present)
 */
extern int ecommunity_strip (struct ecommunity *ecom, uint8_t type, uint8_t subtype)
{
  u_int8_t *p;
  int c, found = 0;
  /* When this is fist value, just add it.  */
  if (ecom == NULL || ecom->val == NULL)
    {
      return 0;
    }

  /* If the value already exists in the structure return 0.  */
  c = 0;
  for (p = ecom->val; c < ecom->size; p += ECOMMUNITY_SIZE, c++)
    {
      if (p[0] == type && p[1] == subtype)
        {
          found = 1;
          break;
        }
    }
  if (found == 0)
    return 0;
  /* Strip The selected value */
  ecom->size--;
  /* size is reduced. no memmove to do */
  p = XMALLOC (MTYPE_ECOMMUNITY_VAL, ecom->size * ECOMMUNITY_SIZE);
  if (c != 0)
    memcpy(p, ecom->val, c * ECOMMUNITY_SIZE);
  if( (ecom->size - c) != 0)
    memcpy(p + (c) * ECOMMUNITY_SIZE,
           ecom->val + (c +1)* ECOMMUNITY_SIZE,
           (ecom->size - c) * ECOMMUNITY_SIZE);
  /* shift last ecommunities */
  XFREE (MTYPE_ECOMMUNITY, ecom->val);
  ecom->val = p;
  return 1;
}