Allow EA type to be set to 'undefined' which overrides all further definitons

of that EA in the same list and causes ea_find() to fail unless you add
EA_ALLOW_UNDEF to the second argument.

ea_sort (resp. ea_do_prune()) removes all undef'd attributes from the list.

I hope this works :)

2 files changed, 33 insertions, 11 deletions

diff --git a/nest/route.h b/nest/route.h
index 799e0a2..e79affb 100644
--- a/nest/route.h
+++ b/nest/route.h
@@ -265,12 +265,16 @@ typedef struct eattr {
 #define EA_PROTO(ea) ((ea) >> 8)
 #define EA_ID(ea) ((ea) & 0xff)
 
+#define EA_CODE_MASK 0xffff
+#define EA_ALLOW_UNDEF 0x10000		/* ea_find: allow EAF_TYPE_UNDEF */
+
 #define EAF_TYPE_MASK 0x0f		/* Mask with this to get type */
 #define EAF_TYPE_INT 0x01		/* 32-bit signed integer number */
 #define EAF_TYPE_OPAQUE 0x02		/* Opaque byte string (not filterable) */
 #define EAF_TYPE_IP_ADDRESS 0x04	/* IP address [FIXME: embed at least for IPv4?] */
 #define EAF_TYPE_AS_PATH 0x06		/* BGP AS path [FIXME: define storage layout] */
 #define EAF_TYPE_INT_SET 0x0a		/* Set of integers (e.g., a community list) */
+#define EAF_TYPE_UNDEF 0x0f		/* `force undefined' entry */
 #define EAF_EMBEDDED 0x01		/* Data stored in eattr.u.data (part of type spec) */
 #define EAF_VAR_LENGTH 0x02		/* Attribute length is variable */
 #define EAF_INLINE 0x80			/* Copy of an attribute inlined in rte (temporary ea_lists only) */
diff --git a/nest/rt-attr.c b/nest/rt-attr.c
index ca6cb10..2c50f4d 100644
--- a/nest/rt-attr.c
+++ b/nest/rt-attr.c
@@ -27,8 +27,8 @@ static pool *rta_pool;
  *	Extended Attributes
  */
 
-eattr *
-ea_find(ea_list *e, unsigned id)
+static inline eattr *
+ea__find(ea_list *e, unsigned id)
 {
   eattr *a;
   int l, r, m;
@@ -60,6 +60,17 @@ ea_find(ea_list *e, unsigned id)
   return NULL;
 }
 
+eattr *
+ea_find(ea_list *e, unsigned id)
+{
+  eattr *a = ea__find(e, id & EA_CODE_MASK);
+
+  if (a && (a->type & EAF_TYPE_MASK) == EAF_TYPE_UNDEF &&
+      !(id & EA_ALLOW_UNDEF))
+    return NULL;
+  return a;
+}
+
 static inline void
 ea_do_sort(ea_list *e)
 {
@@ -107,17 +118,24 @@ ea_do_sort(ea_list *e)
 static inline void
 ea_do_prune(ea_list *e)
 {
-  eattr *s, *d;
-  int i;
+  eattr *s, *d, *l;
+  int i = 0;
 
-  /* Discard duplicates. Do you remember sorting was stable? */
-  s = d = e->attrs + 1;
-  for(i=1; i<e->count; i++)
-    if (s->id != d[-1].id)
-      *d++ = *s++;
-    else
+  /* Discard duplicates and undefs. Do you remember sorting was stable? */
+  s = d = e->attrs;
+  l = e->attrs + e->count;
+  while (s < l)
+    {
+      if ((s->type & EAF_TYPE_MASK) != EAF_TYPE_UNDEF)
+	{
+	  *d++ = *s;
+	  i++;
+	}
       s++;
-  e->count = d - e->attrs;
+      while (s < l && s->id == s[-1].id)
+	s++;
+    }
+  e->count = i;
 }
 
 void