isisd: fixes 6/7: wrong next-hops from SPF

The forwarding table was filled with wrong next-hops, and which is even
worse, it was done in a totally non-deterministic way.

The next-hop set for an IP prefix by isisd was the neighbor IS from which
the flooded LSP about the IP prefix was arrived. So, if an IS received all
the LSPs through its, say, eth0 interface, all entries in the forwarding
table contained the next IS reachable via eth0 as the next-hop.

The solution is to propagate the correct next-hop further from node to node
as the SPF algorithm traverses the graph and selects the next node to be
added to the set of already covered nodes.

Also, the construction of the tentative node list (the nodes where the
shortest path is not known yet) was buggy: if a node was already a member
of this list with a certain path cost, and an alternative path was found to
it with a lower cost while processing a pseudo-node LSP, it was not added
to the list. This way, the path selected by isisd for a certain prefix was
the first one it encountered during the LSDB processing.

Signed-off-by: Fritz Reichmann <fritz@reichmann.nl>

1 files changed, 28 insertions, 25 deletions

diff --git a/isisd/isis_spf.c b/isisd/isis_spf.c
index 5d7e9da4..b6178e3a 100644
--- a/isisd/isis_spf.c
+++ b/isisd/isis_spf.c
@@ -405,12 +405,13 @@ isis_spf_add2tent (struct isis_spftree *spftree, enum vertextype vtype,
 
   if (adj)
     listnode_add (vertex->Adj_N, adj);
+
 #ifdef EXTREME_DEBUG
   zlog_debug ("ISIS-Spf: add to TENT  %s %s depth %d dist %d",
 	      vtype2string (vertex->type), vid2string (vertex, buff),
 	      vertex->depth, vertex->d_N);
 #endif /* EXTREME_DEBUG */
-  listnode_add (spftree->tents, vertex);
+
   if (list_isempty (spftree->tents))
     {
       listnode_add (spftree->tents, vertex);
@@ -549,7 +550,8 @@ process_N (struct isis_spftree *spftree, enum vertextype vtype, void *id,
  */
 static int
 isis_spf_process_lsp (struct isis_spftree *spftree, struct isis_lsp *lsp,
-		      uint32_t cost, uint16_t depth, int family)
+		      uint32_t cost, uint16_t depth, int family,
+		      struct isis_adjacency *adj)
 {
   struct listnode *node, *fragnode = NULL;
   u_int16_t dist;
@@ -563,9 +565,6 @@ isis_spf_process_lsp (struct isis_spftree *spftree, struct isis_lsp *lsp,
   struct ipv6_reachability *ip6reach;
 #endif /* HAVE_IPV6 */
 
-
-  if (!lsp->adj)
-    return ISIS_WARNING;
   if (lsp->tlv_data.nlpids == NULL || !speaks (lsp->tlv_data.nlpids, family))
     return ISIS_OK;
 
@@ -591,7 +590,7 @@ lspfragloop:
 	      vtype = LSP_PSEUDO_ID (is_neigh->neigh_id) ? VTYPE_PSEUDO_IS
 		: VTYPE_NONPSEUDO_IS;
 	      process_N (spftree, vtype, (void *) is_neigh->neigh_id, dist,
-			 depth + 1, lsp->adj, family);
+			 depth + 1, adj, family);
 	    }
 	}
       if (lsp->tlv_data.te_is_neighs)
@@ -607,7 +606,7 @@ lspfragloop:
 	      vtype = LSP_PSEUDO_ID (te_is_neigh->neigh_id) ? VTYPE_PSEUDO_TE_IS
 		: VTYPE_NONPSEUDO_TE_IS;
 	      process_N (spftree, vtype, (void *) te_is_neigh->neigh_id, dist,
-			 depth + 1, lsp->adj, family);
+			 depth + 1, adj, family);
 	    }
 	}
       if (family == AF_INET && lsp->tlv_data.ipv4_int_reachs)
@@ -621,7 +620,7 @@ lspfragloop:
 	      prefix.u.prefix4 = ipreach->prefix;
 	      prefix.prefixlen = ip_masklen (ipreach->mask);
 	      process_N (spftree, vtype, (void *) &prefix, dist, depth + 1,
-			 lsp->adj, family);
+			 adj, family);
 	    }
 	}
 
@@ -636,7 +635,7 @@ lspfragloop:
 	      prefix.u.prefix4 = ipreach->prefix;
 	      prefix.prefixlen = ip_masklen (ipreach->mask);
 	      process_N (spftree, vtype, (void *) &prefix, dist, depth + 1,
-			 lsp->adj, family);
+			 adj, family);
 	    }
 	}
       if (family == AF_INET && lsp->tlv_data.te_ipv4_reachs)
@@ -651,7 +650,7 @@ lspfragloop:
 						   te_ipv4_reach->control);
 	      prefix.prefixlen = (te_ipv4_reach->control & 0x3F);
 	      process_N (spftree, vtype, (void *) &prefix, dist, depth + 1,
-			 lsp->adj, family);
+			 adj, family);
 	    }
 	}
 #ifdef HAVE_IPV6
@@ -668,7 +667,7 @@ lspfragloop:
 	      memcpy (&prefix.u.prefix6.s6_addr, ip6reach->prefix,
 		      PSIZE (ip6reach->prefix_len));
 	      process_N (spftree, vtype, (void *) &prefix, dist, depth + 1,
-			 lsp->adj, family);
+			 adj, family);
 	    }
 	}
 #endif /* HAVE_IPV6 */
@@ -691,7 +690,8 @@ lspfragloop:
 static int
 isis_spf_process_pseudo_lsp (struct isis_spftree *spftree,
 			     struct isis_lsp *lsp, uint16_t cost,
-			     uint16_t depth, int family)
+			     uint16_t depth, int family,
+			     struct isis_adjacency *adj)
 {
   struct listnode *node, *fragnode = NULL;
   struct is_neigh *is_neigh;
@@ -715,13 +715,13 @@ pseudofragloop:
 	/* Two way connectivity */
 	if (!memcmp (is_neigh->neigh_id, isis->sysid, ISIS_SYS_ID_LEN))
 	  continue;
-	if (isis_find_vertex
-	    (spftree->tents, (void *) is_neigh->neigh_id, vtype) == NULL
+	if ((depth > 0 || isis_find_vertex
+	    (spftree->tents, (void *) is_neigh->neigh_id, vtype) == NULL)
 	    && isis_find_vertex (spftree->paths, (void *) is_neigh->neigh_id,
 			       vtype) == NULL)
 	  {
 	    /* C.2.5 i) */
-	    isis_spf_add2tent (spftree, vtype, is_neigh->neigh_id, lsp->adj,
+	    isis_spf_add2tent (spftree, vtype, is_neigh->neigh_id, adj,
 			     cost, depth, family);
 	  }
       }
@@ -733,13 +733,13 @@ pseudofragloop:
 	/* Two way connectivity */
 	if (!memcmp (te_is_neigh->neigh_id, isis->sysid, ISIS_SYS_ID_LEN))
 	  continue;
-	if (isis_find_vertex
-	    (spftree->tents, (void *) te_is_neigh->neigh_id, vtype) == NULL
+	if ((depth > 0 || isis_find_vertex
+	     (spftree->tents, (void *) te_is_neigh->neigh_id, vtype) == NULL)
 	    && isis_find_vertex (spftree->paths, (void *) te_is_neigh->neigh_id,
 				 vtype) == NULL)
 	  {
 	    /* C.2.5 i) */
-	    isis_spf_add2tent (spftree, vtype, te_is_neigh->neigh_id, lsp->adj,
+	    isis_spf_add2tent (spftree, vtype, te_is_neigh->neigh_id, adj,
 			       cost, depth, family);
 	  }
       }
@@ -860,9 +860,6 @@ isis_spf_preload_tent (struct isis_spftree *spftree,
 		  lsp = lsp_search (lsp_id, area->lspdb[level - 1]);
 		  if (!lsp)
 		    zlog_warn ("No lsp found for IS adjacency");
-		  /*          else {
-		     isis_spf_process_lsp (spftree, lsp, vertex->d_N, 1, family);
-		     } */
 		  break;
 		case ISIS_SYSTYPE_UNKNOWN:
 		default:
@@ -885,14 +882,14 @@ isis_spf_preload_tent (struct isis_spftree *spftree,
 	    {
 	      zlog_warn ("ISIS-Spf: No adjacency found for DR");
 	    }
-	  if (lsp == NULL || lsp->lsp_header->rem_lifetime == 0)
+	  else if (lsp == NULL || lsp->lsp_header->rem_lifetime == 0)
 	    {
 	      zlog_warn ("ISIS-Spf: No lsp found for DR");
 	    }
 	  else
 	    {
 	      isis_spf_process_pseudo_lsp (spftree, lsp,
-				  circuit->te_metric[level - 1], 0, family);
+                                           circuit->te_metric[level - 1], 0, family, adj);
 
 	    }
 	}
@@ -982,6 +979,7 @@ isis_run_spf (struct isis_area *area, int level, int family)
   struct isis_spftree *spftree = NULL;
   u_char lsp_id[ISIS_SYS_ID_LEN + 2];
   struct isis_lsp *lsp;
+  struct isis_adjacency *adj = NULL;
   struct route_table *table = NULL;
   struct route_node *rode;
   struct isis_route_info *rinfo;
@@ -1042,6 +1040,11 @@ isis_run_spf (struct isis_area *area, int level, int family)
       if (vertex->type == VTYPE_PSEUDO_IS ||
 	  vertex->type == VTYPE_NONPSEUDO_IS)
 	{
+	  if (listcount(vertex->Adj_N) == 0) {
+	    continue;
+	  }
+	  adj = listgetdata(vertex->Adj_N->head);
+
 	  memcpy (lsp_id, vertex->N.id, ISIS_SYS_ID_LEN + 1);
 	  LSP_FRAGMENT (lsp_id) = 0;
 	  lsp = lsp_search (lsp_id, area->lspdb[level - 1]);
@@ -1050,13 +1053,13 @@ isis_run_spf (struct isis_area *area, int level, int family)
 	      if (LSP_PSEUDO_ID (lsp_id))
 		{
 		  isis_spf_process_pseudo_lsp (spftree, lsp, vertex->d_N,
-					       vertex->depth, family);
+					       vertex->depth, family, adj);
 
 		}
 	      else
 		{
 		  isis_spf_process_lsp (spftree, lsp, vertex->d_N,
-					vertex->depth, family);
+					vertex->depth, family, adj);
 		}
 	    }
 	  else