Commit 775a5a81 authored by Ondrej Zajicek (work)'s avatar Ondrej Zajicek (work)
Browse files

BGP: Skip empty path segments in received AS_PATH 

Although RFC 4271 does not forbid empty path segments, they are useless
and some implementations consider them invalid. It is clarified in RFC 7606,
specifying that AS_PATH with empty segment is considered malformed.
parent 8f01879c

proto/bgp/attrs.c

+13 −11
Original line number Diff line number Diff line
@@ -118,7 +118,7 @@ validate_path(struct bgp_proto *p, int as_path, int bs, byte *idata, uint *ileng 
{

  int res = 0;

  u8 *a, *dst;

  int len, plen, copy;

  int len, plen;



  dst = a = idata;

  len = *ilength;
@@ -132,15 +132,20 @@ validate_path(struct bgp_proto *p, int as_path, int bs, byte *idata, uint *ileng 
      if (len < plen)

	return -1;



      if (a[1] == 0)

        {

	  log(L_WARN "%s: %s_PATH attribute contains empty segment, skipping it",

	      p->p.name, as_path ? "AS" : "AS4");

	  goto skip;

	}



      switch (a[0])

	{

	case AS_PATH_SET:

	  copy = 1;

	  res++;

	  break;



	case AS_PATH_SEQUENCE:

	  copy = 1;

	  res += a[1];

	  break;
@@ -154,20 +159,17 @@ validate_path(struct bgp_proto *p, int as_path, int bs, byte *idata, uint *ileng 


	  log(L_WARN "%s: %s_PATH attribute contains AS_CONFED_* segment, skipping segment",

	      p->p.name, as_path ? "AS" : "AS4");

	  copy = 0;

	  break;

	  goto skip;



	default:

	  return -1;

	}



      if (copy)

	{

      if (dst != a)

	memmove(dst, a, plen);

      dst += plen;

	}



    skip:

      len -= plen;

      a += plen;

    }

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