From: Maria Matejka <mq@ucw.cz>
Date: Mon, 29 Jan 2024 12:58:23 +0000 (+0100)
Subject: BGP: fixed MPLS setting in nexthops
X-Git-Tag: v3.0.0~273
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=058984bc861e938bd274262b939013ae428b38eb;p=thirdparty%2Fbird.git

BGP: fixed MPLS setting in nexthops

bug introduced somewhere during conversion of nexthops to eattrs
---

diff --git a/lib/route.h b/lib/route.h
index f97029319..61f7f3428 100644
--- a/lib/route.h
+++ b/lib/route.h
@@ -162,6 +162,12 @@ struct nexthop_adata {
   };
 };
 
+/* For MPLS label stack generation */
+struct nexthop_adata_mpls {
+  struct nexthop_adata nhad;
+  u32 label_space[MPLS_MAX_LABEL_STACK];
+};
+
 #define NEXTHOP_DEST_SIZE	(OFFSETOF(struct nexthop_adata, dest) + sizeof(uint) - OFFSETOF(struct adata, data))
 #define NEXTHOP_DEST_LITERAL(x)	((struct nexthop_adata) { \
       .ad.length = NEXTHOP_DEST_SIZE, .dest = (x), })
diff --git a/proto/bgp/packets.c b/proto/bgp/packets.c
index 180c0b730..ce7226454 100644
--- a/proto/bgp/packets.c
+++ b/proto/bgp/packets.c
@@ -1104,16 +1104,18 @@ bgp_apply_next_hop(struct bgp_parse_state *s, ea_list **to, ip_addr gw, ip_addr
 
     ea_set_attr_u32(to, &ea_gen_igp_metric, 0, c->cf->cost);
 
-    struct nexthop_adata nhad = {
-      .nh = {
-	.gw = nbr->addr,
-	.iface = nbr->iface,
-      },
-      .ad = {
-	.length = sizeof nhad - sizeof nhad.ad,
+    struct nexthop_adata_mpls nam = {
+      .nhad = {
+	.nh = {
+	  .gw = nbr->addr,
+	  .iface = nbr->iface,
+	},
+	.ad = {
+	  .length = NEXTHOP_NEXT(&nam.nhad.nh) - (void *) nam.nhad.ad.data,
+	},
       },
     };
-    ea_set_attr_data(to, &ea_gen_nexthop, 0, nhad.ad.data, nhad.ad.length);
+    ea_set_attr_data(to, &ea_gen_nexthop, 0, nam.nhad.ad.data, nam.nhad.ad.length);
   }
   else /* GW_RECURSIVE */
   {
@@ -1153,23 +1155,20 @@ bgp_apply_mpls_labels(struct bgp_parse_state *s, ea_list **to, u32 lnum, u32 lab
   if (s->channel->cf->gw_mode == GW_DIRECT)
   {
     eattr *e = ea_find(*to, &ea_gen_nexthop);
-    struct {
-      struct nexthop_adata nhad;
-      u32 labels[MPLS_MAX_LABEL_STACK];
-    } nh;
-    
-    memcpy(&nh.nhad, e->u.ptr, sizeof(struct adata) + e->u.ptr->length);
-    nh.nhad.nh.labels = lnum;
-    memcpy(nh.labels, labels, lnum * sizeof(u32));
-    nh.nhad.ad.length = sizeof nh.nhad + lnum * sizeof(u32);
+    struct nexthop_adata_mpls *namp = SKIP_BACK(struct nexthop_adata_mpls, nhad.ad, e->u.ptr);
+
+    namp->nhad.nh.labels = lnum;
+    memcpy(namp->nhad.nh.label, labels, lnum * sizeof(u32));
+    namp->nhad.ad.length = NEXTHOP_NEXT(&namp->nhad.nh) - (void *) namp->nhad.ad.data;
   }
   else /* GW_RECURSIVE */
   {
     eattr *e = ea_find(*to, &ea_gen_hostentry);
     ASSERT_DIE(e);
     struct hostentry_adata *head = (void *) e->u.ptr;
-    memcpy(&head->labels, labels, lnum * sizeof(u32));
+    memcpy(head->labels, labels, lnum * sizeof(u32));
     head->ad.length = (void *)(&head->labels[lnum]) - (void *) head->ad.data;
+    debug("he %p apply mpls labels (%u): %u\n", head->he, lnum, labels[0]);
   }
 }
 
@@ -1527,9 +1526,6 @@ bgp_rte_update(struct bgp_parse_state *s, const net_addr *n, u32 path_id, ea_lis
 
     s->last_src = rt_get_source(&s->proto->p, path_id);
     s->last_id = path_id;
-
-    ea_free(s->cached_ea);
-    s->cached_ea = NULL;
   }
 
   if (!a0)
@@ -1544,11 +1540,11 @@ bgp_rte_update(struct bgp_parse_state *s, const net_addr *n, u32 path_id, ea_lis
   }
 
   /* Prepare cached route attributes */
-  if (s->cached_ea == NULL)
-    s->cached_ea = ea_lookup(a0, 0);
+  if (!s->mpls && (s->cached_ea == NULL))
+    a0 = s->cached_ea = ea_lookup(a0, 0);
 
   rte e0 = {
-    .attrs = s->cached_ea,
+    .attrs = a0,
     .src = s->last_src,
   };