Netlink: MPLS routes in kernel

Anyway, Bird is now capable to insert both MPLS routes and MPLS encap
routes into kernel.

It was (among others) needed to define platform-specific AF_MPLS to 28
as this constant has been assigned in the linux kernel.

No support for BSD now, it may be added in the future.

10 files changed, 274 insertions, 30 deletions

diff --git a/conf/confbase.Y b/conf/confbase.Y
index 11393fe2..00e78232 100644
--- a/conf/confbase.Y
+++ b/conf/confbase.Y
@@ -270,7 +270,7 @@ net_or_ipa:
 
 label_stack_start: NUM
 {
-  $$ = cfg_allocz(sizeof(u32) * (NEXTHOP_MAX_LABEL_STACK+1));
+  $$ = cfg_allocz(sizeof(u32) * (MPLS_MAX_LABEL_STACK+1));
   $$[0] = 1;
   $$[1] = $1;
 };
@@ -278,7 +278,7 @@ label_stack_start: NUM
 label_stack:
     label_stack_start
   | label_stack '/' NUM {
-    if ($1[0] >= NEXTHOP_MAX_LABEL_STACK)
+    if ($1[0] >= MPLS_MAX_LABEL_STACK)
       cf_error("Too many labels in stack.");
     $1[++$1[0]] = $3;
     $$ = $1;
diff --git a/lib/ip.h b/lib/ip.h
index 86750675..ab90bee7 100644
--- a/lib/ip.h
+++ b/lib/ip.h
@@ -325,6 +325,28 @@ static inline ip6_addr ip6_hton(ip6_addr a)
 static inline ip6_addr ip6_ntoh(ip6_addr a)
 { return _MI6(ntohl(_I0(a)), ntohl(_I1(a)), ntohl(_I2(a)), ntohl(_I3(a))); }
 
+#define MPLS_MAX_LABEL_STACK 8
+static inline int
+mpls_get(const char *buf, int buflen, u32 *stack)
+{
+  for (int i=0; (i<MPLS_MAX_LABEL_STACK) && (i*4+3 < buflen); i++)
+  {
+    u32 s = get_u32(buf + i*4);
+    stack[i] = s >> 12;
+    if (s & 0x100)
+      return i+1;
+  }
+  return -1;
+}
+
+static inline int
+mpls_put(char *buf, int len, u32 *stack)
+{
+  for (int i=0; i<len; i++)
+    put_u32(buf + i*4, stack[i] << 12 | (i+1 == len ? 0x100 : 0));
+
+  return len*4;
+}
 
 /*
  *	Unaligned data access (in network order)
diff --git a/lib/net.c b/lib/net.c
index 91a4474a..5a7e6fec 100644
--- a/lib/net.c
+++ b/lib/net.c
@@ -225,7 +225,8 @@ net_classify(const net_addr *N)
   case NET_FLOW6:
     return ip6_zero(n->ip6.prefix) ? (IADDR_HOST | SCOPE_UNIVERSE) : ip6_classify(&n->ip6.prefix);
 
-  /* classify probably not needed for NET_MPLS */
+  case NET_MPLS:
+    return IADDR_HOST | SCOPE_UNIVERSE;
   }
 
   return IADDR_INVALID;
diff --git a/lib/net.h b/lib/net.h
index 5fc4dab7..7c124fc0 100644
--- a/lib/net.h
+++ b/lib/net.h
@@ -259,6 +259,14 @@ static inline ip_addr net_prefix(const net_addr *a)
   }
 }
 
+static inline u32 net_mpls(const net_addr *a)
+{
+  if (a->type == NET_MPLS)
+    return ((net_addr_mpls *) a)->label;
+
+  bug("Can't call net_mpls on non-mpls net_addr");
+}
+
 static inline uint net4_pxlen(const net_addr *a)
 { return a->pxlen; }
 
diff --git a/nest/route.h b/nest/route.h
index c293fbb1..a2fadf62 100644
--- a/nest/route.h
+++ b/nest/route.h
@@ -512,8 +512,7 @@ uint ea_hash(ea_list *e);	/* Calculate 16-bit hash value */
 ea_list *ea_append(ea_list *to, ea_list *what);
 void ea_format_bitfield(struct eattr *a, byte *buf, int bufsize, const char **names, int min, int max);
 
-#define NEXTHOP_MAX_LABEL_STACK 8
-#define NEXTHOP_MAX_SIZE (sizeof(struct nexthop) + sizeof(u32)*NEXTHOP_MAX_LABEL_STACK)
+#define NEXTHOP_MAX_SIZE (sizeof(struct nexthop) + sizeof(u32)*MPLS_MAX_LABEL_STACK)
 
 static inline size_t nexthop_size(const struct nexthop *nh)
 { return sizeof(struct nexthop) + sizeof(u32)*nh->labels; }
@@ -528,7 +527,7 @@ int nexthop_is_sorted(struct nexthop *x);
 
 void rta_init(void);
 static inline size_t rta_size(const rta *a) { return sizeof(rta) + sizeof(u32)*a->nh.labels; }
-#define RTA_MAX_SIZE (sizeof(rta) + sizeof(u32)*NEXTHOP_MAX_LABEL_STACK)
+#define RTA_MAX_SIZE (sizeof(rta) + sizeof(u32)*MPLS_MAX_LABEL_STACK)
 rta *rta_lookup(rta *);			/* Get rta equivalent to this one, uc++ */
 static inline int rta_is_cached(rta *r) { return r->aflags & RTAF_CACHED; }
 static inline rta *rta_clone(rta *r) { r->uc++; return r; }
diff --git a/nest/rt-attr.c b/nest/rt-attr.c
index 22a5cb14..120a8e24 100644
--- a/nest/rt-attr.c
+++ b/nest/rt-attr.c
@@ -1279,12 +1279,12 @@ rta_init(void)
   rta_slab_[0] = sl_new(rta_pool, sizeof(rta));
   rta_slab_[1] = sl_new(rta_pool, sizeof(rta) + sizeof(u32));
   rta_slab_[2] = sl_new(rta_pool, sizeof(rta) + sizeof(u32)*2);
-  rta_slab_[3] = sl_new(rta_pool, sizeof(rta) + sizeof(u32)*NEXTHOP_MAX_LABEL_STACK);
+  rta_slab_[3] = sl_new(rta_pool, sizeof(rta) + sizeof(u32)*MPLS_MAX_LABEL_STACK);
 
   nexthop_slab_[0] = sl_new(rta_pool, sizeof(struct nexthop));
   nexthop_slab_[1] = sl_new(rta_pool, sizeof(struct nexthop) + sizeof(u32));
   nexthop_slab_[2] = sl_new(rta_pool, sizeof(struct nexthop) + sizeof(u32)*2);
-  nexthop_slab_[3] = sl_new(rta_pool, sizeof(struct nexthop) + sizeof(u32)*NEXTHOP_MAX_LABEL_STACK);
+  nexthop_slab_[3] = sl_new(rta_pool, sizeof(struct nexthop) + sizeof(u32)*MPLS_MAX_LABEL_STACK);
 
   rta_alloc_hash();
   rte_src_init();
diff --git a/nest/rt-table.c b/nest/rt-table.c
index 92542ea8..73b838be 100644
--- a/nest/rt-table.c
+++ b/nest/rt-table.c
@@ -2487,7 +2487,7 @@ rt_show_rte(struct cli *c, byte *ia, rte *e, struct rt_show_data *d, ea_list *tm
 	     tm, from, primary ? (sync_error ? " !" : " *") : "", info);
   for (nh = &(a->nh); nh; nh = nh->next)
     {
-      char ls[NEXTHOP_MAX_LABEL_STACK*8 + 5]; char *lsp = ls;
+      char ls[MPLS_MAX_LABEL_STACK*8 + 5]; char *lsp = ls;
       if (nh->labels)
 	{
 	  lsp += bsprintf(lsp, " mpls %d", nh->label[0]);
diff --git a/sysdep/cf/linux.h b/sysdep/cf/linux.h
index cec9499c..3a3a15da 100644
--- a/sysdep/cf/linux.h
+++ b/sysdep/cf/linux.h
@@ -21,6 +21,10 @@
 #define CONFIG_INCLUDE_SYSPRIV_H "sysdep/linux/syspriv.h"
 
 
+#ifndef AF_MPLS
+#define AF_MPLS 28
+#endif
+
 /*
 Link: sysdep/linux
 Link: sysdep/unix
diff --git a/sysdep/linux/netlink.c b/sysdep/linux/netlink.c
index c9a30719..23431172 100644
--- a/sysdep/linux/netlink.c
+++ b/sysdep/linux/netlink.c
@@ -31,6 +31,7 @@
 
 #include <asm/types.h>
 #include <linux/if.h>
+#include <linux/lwtunnel.h>
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
 
@@ -51,6 +52,21 @@
 #define RTA_TABLE  15
 #endif
 
+#ifndef RTA_VIA
+#define RTA_VIA	 18
+#endif
+
+#ifndef RTA_NEWDST
+#define RTA_NEWDST  19
+#endif
+
+#ifndef RTA_ENCAP_TYPE
+#define RTA_ENCAP_TYPE	21
+#endif
+
+#ifndef RTA_ENCAP
+#define RTA_ENCAP  22
+#endif
 
 #define krt_ecmp6(p) ((p)->af == AF_INET6)
 
@@ -313,10 +329,16 @@ static struct nl_want_attrs ifa_attr_want6[BIRD_IFA_MAX] = {
 };
 
 
-#define BIRD_RTA_MAX  (RTA_TABLE+1)
+#define BIRD_RTA_MAX  (RTA_ENCAP+1)
 
 static struct nl_want_attrs nexthop_attr_want4[BIRD_RTA_MAX] = {
   [RTA_GATEWAY]	  = { 1, 1, sizeof(ip4_addr) },
+  [RTA_ENCAP_TYPE]= { 1, 1, sizeof(u16) },
+  [RTA_ENCAP]	  = { 1, 0, 0 },
+};
+
+static struct nl_want_attrs encap_mpls_want[BIRD_RTA_MAX] = {
+  [RTA_DST]       = { 1, 0, 0 },
 };
 
 static struct nl_want_attrs rtm_attr_want4[BIRD_RTA_MAX] = {
@@ -329,6 +351,8 @@ static struct nl_want_attrs rtm_attr_want4[BIRD_RTA_MAX] = {
   [RTA_MULTIPATH] = { 1, 0, 0 },
   [RTA_FLOW]	  = { 1, 1, sizeof(u32) },
   [RTA_TABLE]	  = { 1, 1, sizeof(u32) },
+  [RTA_ENCAP_TYPE]= { 1, 1, sizeof(u16) },
+  [RTA_ENCAP]	  = { 1, 0, 0 },
 };
 
 static struct nl_want_attrs rtm_attr_want6[BIRD_RTA_MAX] = {
@@ -341,6 +365,20 @@ static struct nl_want_attrs rtm_attr_want6[BIRD_RTA_MAX] = {
   [RTA_METRICS]	  = { 1, 0, 0 },
   [RTA_FLOW]	  = { 1, 1, sizeof(u32) },
   [RTA_TABLE]	  = { 1, 1, sizeof(u32) },
+  [RTA_ENCAP_TYPE]= { 1, 1, sizeof(u16) },
+  [RTA_ENCAP]	  = { 1, 0, 0 },
+};
+
+static struct nl_want_attrs rtm_attr_want_mpls[BIRD_RTA_MAX] = {
+  [RTA_DST]	  = { 1, 1, sizeof(u32) },
+  [RTA_IIF]	  = { 1, 1, sizeof(u32) },
+  [RTA_OIF]	  = { 1, 1, sizeof(u32) },
+  [RTA_PRIORITY]  = { 1, 1, sizeof(u32) },
+  [RTA_METRICS]	  = { 1, 0, 0 },
+  [RTA_FLOW]	  = { 1, 1, sizeof(u32) },
+  [RTA_TABLE]	  = { 1, 1, sizeof(u32) },
+  [RTA_VIA]	  = { 1, 0, 0 },
+  [RTA_NEWDST]	  = { 1, 0, 0 },
 };
 
 
@@ -373,6 +411,9 @@ nl_parse_attrs(struct rtattr *a, struct nl_want_attrs *want, struct rtattr **k,
   return 1;
 }
 
+static inline u16 rta_get_u16(struct rtattr *a)
+{ return *(u16 *) RTA_DATA(a); }
+
 static inline u32 rta_get_u32(struct rtattr *a)
 { return *(u32 *) RTA_DATA(a); }
 
@@ -390,6 +431,25 @@ static inline ip_addr rta_get_ipa(struct rtattr *a)
     return ipa_from_ip6(rta_get_ip6(a));
 }
 
+static inline ip_addr rta_get_via(struct rtattr *a)
+{
+  struct rtvia *v = RTA_DATA(a);
+  switch(v->rtvia_family) {
+    case AF_INET:  return ipa_from_ip4(ip4_ntoh(*(ip4_addr *) v->rtvia_addr));
+    case AF_INET6: return ipa_from_ip6(ip6_ntoh(*(ip6_addr *) v->rtvia_addr));
+  }
+  return IPA_NONE;
+}
+
+static u32 rta_mpls_stack[MPLS_MAX_LABEL_STACK];
+static inline int rta_get_mpls(struct rtattr *a, u32 *stack)
+{
+  if (RTA_PAYLOAD(a) % 4)
+    log(L_WARN "KRT: Strange length of received MPLS stack: %u", RTA_PAYLOAD(a));
+
+  return mpls_get(RTA_DATA(a), RTA_PAYLOAD(a) & ~0x3, stack);
+}
+
 struct rtattr *
 nl_add_attr(struct nlmsghdr *h, uint bufsize, uint code, const void *data, uint dlen)
 {
@@ -410,6 +470,24 @@ nl_add_attr(struct nlmsghdr *h, uint bufsize, uint code, const void *data, uint
   return a;
 }
 
+static inline struct rtattr *
+nl_open_attr(struct nlmsghdr *h, uint bufsize, uint code)
+{
+  return nl_add_attr(h, bufsize, code, NULL, 0);
+}
+
+static inline void
+nl_close_attr(struct nlmsghdr *h, struct rtattr *a)
+{
+  a->rta_len = (void *)h + NLMSG_ALIGN(h->nlmsg_len) - (void *)a;
+}
+
+static inline void
+nl_add_attr_u16(struct nlmsghdr *h, uint bufsize, int code, u16 data)
+{
+  nl_add_attr(h, bufsize, code, &data, 2);
+}
+
 static inline void
 nl_add_attr_u32(struct nlmsghdr *h, uint bufsize, int code, u32 data)
 {
@@ -439,16 +517,47 @@ nl_add_attr_ipa(struct nlmsghdr *h, uint bufsize, int code, ip_addr ipa)
     nl_add_attr_ip6(h, bufsize, code, ipa_to_ip6(ipa));
 }
 
-static inline struct rtattr *
-nl_open_attr(struct nlmsghdr *h, uint bufsize, uint code)
+static inline void
+nl_add_attr_mpls(struct nlmsghdr *h, uint bufsize, int code, int len, u32 *stack)
 {
-  return nl_add_attr(h, bufsize, code, NULL, 0);
+  char buf[len*4];
+  mpls_put(buf, len, stack);
+  nl_add_attr(h, bufsize, code, buf, len*4);
 }
 
 static inline void
-nl_close_attr(struct nlmsghdr *h, struct rtattr *a)
+nl_add_attr_mpls_encap(struct nlmsghdr *h, uint bufsize, int len, u32 *stack)
 {
-  a->rta_len = (void *)h + NLMSG_ALIGN(h->nlmsg_len) - (void *)a;
+  nl_add_attr_u16(h, bufsize, RTA_ENCAP_TYPE, LWTUNNEL_ENCAP_MPLS);
+
+  struct rtattr *nest = nl_open_attr(h, bufsize, RTA_ENCAP);
+  nl_add_attr_mpls(h, bufsize, RTA_DST, len, stack);
+  nl_close_attr(h, nest);
+}
+
+static inline void
+nl_add_attr_via(struct nlmsghdr *h, uint bufsize, ip_addr ipa)
+{
+  struct rtattr *nest = nl_open_attr(h, bufsize, RTA_VIA);
+  struct rtvia *via = RTA_DATA(nest);
+
+  h->nlmsg_len += sizeof(*via);
+
+  if (ipa_is_ip4(ipa)) {
+    ip4_addr ip4 = ipa_to_ip4(ipa);
+    ip4 = ip4_hton(ip4);
+    via->rtvia_family = AF_INET;
+    memcpy(via->rtvia_addr, &ip4, sizeof(ip4));
+    h->nlmsg_len += sizeof(ip4);
+  } else {
+    ip6_addr ip6 = ipa_to_ip6(ipa);
+    ip6 = ip6_hton(ip6);
+    via->rtvia_family = AF_INET6;
+    memcpy(via->rtvia_addr, &ip6, sizeof(ip6));
+    h->nlmsg_len += sizeof(ip6);
+  }
+
+  nl_close_attr(h, nest);
 }
 
 static inline struct rtnexthop *
@@ -471,8 +580,24 @@ nl_close_nexthop(struct nlmsghdr *h, struct rtnexthop *nh)
   nh->rtnh_len = (void *)h + NLMSG_ALIGN(h->nlmsg_len) - (void *)nh;
 }
 
+static inline void
+nl_add_nexthop(struct nlmsghdr *h, uint bufsize, struct nexthop *nh, int af)
+{
+  if (nh->labels > 0)
+    if (af == AF_MPLS)
+      nl_add_attr_mpls(h, bufsize, RTA_NEWDST, nh->labels, nh->label);
+    else
+      nl_add_attr_mpls_encap(h, bufsize, nh->labels, nh->label);
+
+  if (ipa_nonzero(nh->gw))
+    if (af == AF_MPLS)
+      nl_add_attr_via(h, bufsize, nh->gw);
+    else
+      nl_add_attr_ipa(h, bufsize, RTA_GATEWAY, nh->gw);
+}
+
 static void
-nl_add_multipath(struct nlmsghdr *h, uint bufsize, struct nexthop *nh)
+nl_add_multipath(struct nlmsghdr *h, uint bufsize, struct nexthop *nh, int af)
 {
   struct rtattr *a = nl_open_attr(h, bufsize, RTA_MULTIPATH);
 
@@ -484,7 +609,7 @@ nl_add_multipath(struct nlmsghdr *h, uint bufsize, struct nexthop *nh)
     rtnh->rtnh_hops = nh->weight;
     rtnh->rtnh_ifindex = nh->iface->index;
 
-    nl_add_attr_ipa(h, bufsize, RTA_GATEWAY, nh->gw);
+    nl_add_nexthop(h, bufsize, nh, af);
 
     nl_close_nexthop(h, rtnh);
   }
@@ -518,7 +643,7 @@ nl_parse_multipath(struct krt_proto *p, struct rtattr *ra)
       if (nh_buf_used == nh_buf_size)
       {
 	nh_buf_size = nh_buf_size ? (nh_buf_size * 2) : 4;
-	nh_buffer = xrealloc(nh_buffer, nh_buf_size * sizeof(struct nexthop));
+	nh_buffer = xrealloc(nh_buffer, nh_buf_size * NEXTHOP_MAX_SIZE);
       }
       *last = rv = nh_buffer + nh_buf_used++;
       rv->next = NULL;
@@ -543,7 +668,21 @@ nl_parse_multipath(struct krt_proto *p, struct rtattr *ra)
 	    return NULL;
 	}
       else
-	return NULL;
+	rv->gw = IPA_NONE;
+      if (a[RTA_ENCAP_TYPE])
+	{
+	  if (rta_get_u16(a[RTA_ENCAP_TYPE]) != LWTUNNEL_ENCAP_MPLS) {
+	    log(L_WARN "KRT: Unknown encapsulation method %d in multipath", rta_get_u16(a[RTA_ENCAP_TYPE]));
+	    return NULL;
+	  }
+
+	  struct rtattr *enca[BIRD_RTA_MAX];
+	  nl_attr_len = RTA_PAYLOAD(a[RTA_ENCAP]);
+	  nl_parse_attrs(RTA_DATA(a[RTA_ENCAP]), encap_mpls_want, enca, sizeof(enca));
+	  rv->labels = rta_get_mpls(enca[RTA_DST], rv->label);
+	  break;
+	}
+
 
       len -= NLMSG_ALIGN(nh->rtnh_len);
       nh = RTNH_NEXT(nh);
@@ -1008,7 +1147,13 @@ nl_send_route(struct krt_proto *p, rte *e, struct ea_list *eattrs, int op, int d
   r->r.rtm_dst_len = net_pxlen(net->n.addr);
   r->r.rtm_protocol = RTPROT_BIRD;
   r->r.rtm_scope = RT_SCOPE_UNIVERSE;
-  nl_add_attr_ipa(&r->h, rsize, RTA_DST, net_prefix(net->n.addr));
+  if (p->af == AF_MPLS)
+  {
+    u32 label = net_mpls(net->n.addr);
+    nl_add_attr_mpls(&r->h, rsize, RTA_DST, 1, &label);
+  }
+  else
+    nl_add_attr_ipa(&r->h, rsize, RTA_DST, net_prefix(net->n.addr));
 
   /*
    * Strange behavior for RTM_DELROUTE:
@@ -1071,13 +1216,11 @@ dest:
     case RTD_UNICAST:
       r->r.rtm_type = RTN_UNICAST;
       if (nh->next && !krt_ecmp6(p))
-	nl_add_multipath(&r->h, rsize, nh);
+	nl_add_multipath(&r->h, rsize, nh, p->af);
       else
       {
 	nl_add_attr_u32(&r->h, rsize, RTA_OIF, nh->iface->index);
-
-	if (ipa_nonzero(nh->gw))
-	  nl_add_attr_ipa(&r->h, rsize, RTA_GATEWAY, nh->gw);
+	nl_add_nexthop(&r->h, rsize, nh, p->af);
       }
       break;
     case RTD_BLACKHOLE:
@@ -1276,6 +1419,19 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
 	net_fill_ip6(&dst, IP6_NONE, 0);
       break;
 
+    case AF_MPLS:
+      if (!nl_parse_attrs(RTM_RTA(i), rtm_attr_want_mpls, a, sizeof(a)))
+	return;
+
+      if (a[RTA_DST])
+	if (rta_get_mpls(a[RTA_DST], rta_mpls_stack) == 1)
+	  net_fill_mpls(&dst, rta_mpls_stack[0]);
+	else
+	  log(L_WARN "KRT: Got multi-label MPLS RTA_DST");
+      else
+	return; /* No support for MPLS routes without RTA_DST */
+      break;
+
     default:
       return;
     }
@@ -1338,7 +1494,7 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
   if (s->net && !nl_mergable_route(s, net, p, priority, i->rtm_type))
     nl_announce_route(s);
 
-  rta *ra = lp_allocz(s->pool, sizeof(rta)); // TODO: fix alloc
+  rta *ra = lp_allocz(s->pool, RTA_MAX_SIZE);
   ra->src = p->p.main_source;
   ra->source = RTS_INHERIT;
   ra->scope = SCOPE_UNIVERSE;
@@ -1367,9 +1523,12 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
 	  return;
 	}
 
-      if (a[RTA_GATEWAY])
+      if ((i->rtm_family != AF_MPLS) && a[RTA_GATEWAY] || (i->rtm_family == AF_MPLS) && a[RTA_VIA])
 	{
-	  ra->nh.gw = rta_get_ipa(a[RTA_GATEWAY]);
+	  if (i->rtm_family == AF_MPLS)
+	    ra->nh.gw = rta_get_via(a[RTA_VIA]);
+	  else
+	    ra->nh.gw = rta_get_ipa(a[RTA_GATEWAY]);
 
 	  /* Silently skip strange 6to4 routes */
 	  const net_addr_ip6 sit = NET_ADDR_IP6(IP6_NONE, 96);
@@ -1377,7 +1536,7 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
 	    return;
 
 	  neighbor *nbr;
-	  nbr = neigh_find2(&p->p, &ra->nh.gw, ra->nh.iface,
+	  nbr = neigh_find2(&p->p, &(ra->nh.gw), ra->nh.iface,
 			    (i->rtm_flags & RTNH_F_ONLINK) ? NEF_ONLINK : 0);
 	  if (!nbr || (nbr->scope == SCOPE_HOST))
 	    {
@@ -1403,6 +1562,44 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
       return;
     }
 
+  int labels = 0;
+  if ((i->rtm_family == AF_MPLS) && a[RTA_NEWDST] && !ra->nh.next)
+    labels = rta_get_mpls(a[RTA_NEWDST], ra->nh.label);
+
+  if (a[RTA_ENCAP] && a[RTA_ENCAP_TYPE] && !ra->nh.next)
+    {
+      switch (rta_get_u16(a[RTA_ENCAP_TYPE]))
+	{
+	  case LWTUNNEL_ENCAP_MPLS:
+	    {
+	      struct rtattr *enca[BIRD_RTA_MAX];
+	      nl_attr_len = RTA_PAYLOAD(a[RTA_ENCAP]);
+	      nl_parse_attrs(RTA_DATA(a[RTA_ENCAP]), encap_mpls_want, enca, sizeof(enca));
+	      labels = rta_get_mpls(enca[RTA_DST], ra->nh.label);
+	      break;
+	    }
+	  default:
+	    SKIP("unknown encapsulation method %d\n", rta_get_u16(a[RTA_ENCAP_TYPE]));
+	    break;
+	}
+    }
+
+  if (labels < 0)
+  {
+    log(L_WARN "KRT: Too long MPLS stack received, ignoring.");
+    ra->nh.labels = 0;
+  }
+  else
+    ra->nh.labels = labels;
+
+  rte *e = rte_get_temp(ra);
+  e->net = net;
+  e->u.krt.src = src;
+  e->u.krt.proto = i->rtm_protocol;
+  e->u.krt.seen = 0;
+  e->u.krt.best = 0;
+  e->u.krt.metric = 0;
+
   if (i->rtm_scope != def_scope)
     {
       ea_list *ea = lp_alloc(s->pool, sizeof(ea_list) + sizeof(eattr));
@@ -1416,6 +1613,9 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
       ea->attrs[0].u.data = i->rtm_scope;
     }
 
+  if (a[RTA_PRIORITY])
+    e->u.krt.metric = rta_get_u32(a[RTA_PRIORITY]);
+
   if (a[RTA_PREFSRC])
     {
       ip_addr ps = rta_get_ipa(a[RTA_PREFSRC]);
@@ -1527,6 +1727,15 @@ krt_do_scan(struct krt_proto *p UNUSED)	/* CONFIG_ALL_TABLES_AT_ONCE => p is NUL
     else
       log(L_DEBUG "nl_scan_fire: Unknown packet received (type=%d)", h->nlmsg_type);
   nl_parse_end(&s);
+
+  nl_parse_begin(&s, 1, 1);
+  nl_request_dump(AF_MPLS, RTM_GETROUTE);
+  while (h = nl_get_scan())
+    if (h->nlmsg_type == RTM_NEWROUTE || h->nlmsg_type == RTM_DELROUTE)
+      nl_parse_route(&s, h);
+    else
+      log(L_DEBUG "nl_scan_fire: Unknown packet received (type=%d)", h->nlmsg_type);
+  nl_parse_end(&s);
 }
 
 /*
diff --git a/sysdep/unix/krt.c b/sysdep/unix/krt.c
index 9f66d2f4..c273cb10 100644
--- a/sysdep/unix/krt.c
+++ b/sysdep/unix/krt.c
@@ -1153,7 +1153,8 @@ krt_start(struct proto *P)
   {
   case NET_IP4:	p->af = AF_INET; break;
   case NET_IP6:	p->af = AF_INET6; break;
-  default:	ASSERT(0);
+  case NET_MPLS: p->af = AF_MPLS; break;
+  default: log(L_ERR "KRT: Tried to start with strange net type: %d", p->p.net_type); return PS_START; break;
   }
 
   add_tail(&krt_proto_list, &p->krt_node);
@@ -1264,7 +1265,7 @@ struct protocol proto_unix_kernel = {
   .template =		"kernel%d",
   .attr_class =		EAP_KRT,
   .preference =		DEF_PREF_INHERITED,
-  .channel_mask =	NB_IP,
+  .channel_mask =	NB_IP | NB_MPLS,
   .proto_size =		sizeof(struct krt_proto),
   .config_size =	sizeof(struct krt_config),
   .preconfig =		krt_preconfig,