1 files changed, 491 insertions, 0 deletions

diff --git a/proto/l3vpn/l3vpn.c b/proto/l3vpn/l3vpn.c
new file mode 100644
index 00000000..8b56cd73
--- /dev/null
+++ b/proto/l3vpn/l3vpn.c
@@ -0,0 +1,491 @@
+/*
+ *	BIRD -- BGP/MPLS IP Virtual Private Networks (L3VPN)
+ *
+ *	(c) 2022 Ondrej Zajicek <santiago@crfreenet.org>
+ *	(c) 2022 CZ.NIC z.s.p.o.
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+/**
+ * DOC: L3VPN
+ *
+ * The L3VPN protocol implements RFC 4364 BGP/MPLS VPNs using MPLS backbone.
+ * It works similarly to pipe. It connects IP table (one per VRF) with (global)
+ * VPN table. Routes passed from VPN table to IP table are stripped of RD and
+ * filtered by import targets, routes passed in the other direction are extended
+ * with RD, MPLS labels and export targets in extended communities. Separate
+ * MPLS channel is used to announce MPLS routes for the labels.
+ *
+ * Note that in contrast to the pipe protocol, L3VPN protocol has both IPv4 and
+ * IPv6 channels in one instance, Also both IP and VPN channels are presented to
+ * users as separate channels, although that will change in the future.
+ *
+ * The L3VPN protocol has different default preferences on IP and VPN sides.
+ * The reason is that in import direction (VPN->IP) routes should have lower
+ * preferences that ones received from local CE (perhaps by EBGP), while in
+ * export direction (IP->VPN) routes should have higher preferences that ones
+ * received from remote PEs (by IBGP).
+ *
+ * Supported standards:
+ * RFC 4364 - BGP/MPLS IP Virtual Private Networks (L3VPN)
+ */
+
+#undef LOCAL_DEBUG
+
+#include "nest/bird.h"
+#include "nest/iface.h"
+#include "nest/protocol.h"
+#include "nest/route.h"
+#include "nest/mpls.h"
+#include "nest/cli.h"
+#include "conf/conf.h"
+#include "filter/filter.h"
+#include "filter/data.h"
+#include "lib/string.h"
+
+#include "l3vpn.h"
+
+#include "proto/bgp/bgp.h"
+
+/*
+ * TODO:
+ * - check for simple nodes in export route
+ * - replace pair of channels with shared channel for one address family
+ * - improve route comparisons in VRFs
+ * - optional import/export target all
+ * - optional support for route origins
+ * - optional automatic assignment of RDs
+ * - MPLS-in-IP encapsulation
+ */
+
+#define EA_BGP_NEXT_HOP		EA_CODE(PROTOCOL_BGP, BA_NEXT_HOP)
+#define EA_BGP_EXT_COMMUNITY	EA_CODE(PROTOCOL_BGP, BA_EXT_COMMUNITY)
+#define EA_BGP_MPLS_LABEL_STACK	EA_CODE(PROTOCOL_BGP, BA_MPLS_LABEL_STACK)
+
+static inline const struct adata * ea_get_adata(ea_list *e, uint id)
+{ eattr *a = ea_find(e, id); return a ? a->u.ptr : &null_adata; }
+
+static inline int
+mpls_valid_nexthop(const rta *a)
+{
+  /* MPLS does not support special blackhole targets */
+  if (a->dest != RTD_UNICAST)
+    return 0;
+
+  /* MPLS does not support ARP / neighbor discovery */
+  for (const struct nexthop *nh = &a->nh; nh ; nh = nh->next)
+    if (ipa_zero(nh->gw) && (nh->iface->flags & IF_MULTIACCESS))
+      return 0;
+
+  return 1;
+}
+
+static int
+l3vpn_import_targets(struct l3vpn_proto *p, const struct adata *list)
+{
+  return (p->import_target_one) ?
+    ec_set_contains(list, p->import_target->from.val.ec) :
+    eclist_match_set(list, p->import_target);
+}
+
+static struct adata *
+l3vpn_export_targets(struct l3vpn_proto *p, const struct adata *src)
+{
+  u32 *s = int_set_get_data(src);
+  int len = int_set_get_size(src);
+
+  struct adata *dst = lp_alloc(tmp_linpool, sizeof(struct adata) + (len + p->export_target_length) * sizeof(u32));
+  u32 *d = int_set_get_data(dst);
+  int end = 0;
+
+  for (int i = 0; i < len; i += 2)
+  {
+    /* Remove existing route targets */
+    uint type = s[i] >> 16;
+    if (ec_type_is_rt(type))
+      continue;
+
+    d[end++] = s[i];
+    d[end++] = s[i+1];
+  }
+
+  /* Add new route targets */
+  memcpy(d + end, p->export_target_data, p->export_target_length * sizeof(u32));
+  end += p->export_target_length;
+
+  /* Set length */
+  dst->length = end * sizeof(u32);
+
+  return dst;
+}
+
+static inline void
+l3vpn_prepare_import_targets(struct l3vpn_proto *p)
+{
+  const struct f_tree *t = p->import_target;
+  p->import_target_one = !t->left && !t->right && (t->from.val.ec == t->to.val.ec);
+}
+
+static void
+l3vpn_add_ec(const struct f_tree *t, void *P)
+{
+  struct l3vpn_proto *p = P;
+  ec_put(p->export_target_data, p->export_target_length, t->from.val.ec);
+  p->export_target_length += 2;
+}
+
+static void
+l3vpn_prepare_export_targets(struct l3vpn_proto *p)
+{
+  if (p->export_target_data)
+    mb_free(p->export_target_data);
+
+  uint len = 2 * tree_node_count(p->export_target);
+  p->export_target_data = mb_alloc(p->p.pool, len * sizeof(u32));
+  p->export_target_length = 0;
+  tree_walk(p->export_target, l3vpn_add_ec, p);
+  ASSERT(p->export_target_length == len);
+}
+
+static void
+l3vpn_rt_notify(struct proto *P, struct channel *c0, net *net, rte *new, rte *old UNUSED)
+{
+  struct l3vpn_proto *p = (void *) P;
+  struct rte_src *src = NULL;
+  struct channel *dst = NULL;
+  int export;
+
+  const net_addr *n0 = net->n.addr;
+  net_addr *n = alloca(sizeof(net_addr_vpn6));
+
+  switch (c0->net_type)
+  {
+  case NET_IP4:
+    net_fill_vpn4(n, net4_prefix(n0), net4_pxlen(n0), p->rd);
+    src = p->p.main_source;
+    dst = p->vpn4_channel;
+    export = 1;
+    break;
+
+  case NET_IP6:
+    net_fill_vpn6(n, net6_prefix(n0), net6_pxlen(n0), p->rd);
+    src = p->p.main_source;
+    dst = p->vpn6_channel;
+    export = 1;
+    break;
+
+  case NET_VPN4:
+    net_fill_ip4(n, net4_prefix(n0), net4_pxlen(n0));
+    src = rt_get_source(&p->p, ((const net_addr_vpn4 *) n0)->rd);
+    dst = p->ip4_channel;
+    export = 0;
+    break;
+
+  case NET_VPN6:
+    net_fill_ip6(n, net6_prefix(n0), net6_pxlen(n0));
+    src = rt_get_source(&p->p, ((const net_addr_vpn6 *) n0)->rd);
+    dst = p->ip6_channel;
+    export = 0;
+    break;
+
+  case NET_MPLS:
+    return;
+  }
+
+  if (new)
+  {
+    const rta *a0 = new->attrs;
+    rta *a = alloca(RTA_MAX_SIZE);
+    *a = (rta) {
+      .source = RTS_L3VPN,
+      .scope = SCOPE_UNIVERSE,
+      .dest = a0->dest,
+      .pref = dst->preference,
+      .eattrs = a0->eattrs
+    };
+
+    nexthop_link(a, &a0->nh);
+
+    /* Do not keep original labels, we may assign new ones */
+    ea_unset_attr(&a->eattrs, tmp_linpool, 0, EA_MPLS_LABEL);
+    ea_unset_attr(&a->eattrs, tmp_linpool, 0, EA_MPLS_POLICY);
+
+    /* We are crossing VRF boundary, NEXT_HOP is no longer valid */
+    ea_unset_attr(&a->eattrs, tmp_linpool, 0, EA_BGP_NEXT_HOP);
+    ea_unset_attr(&a->eattrs, tmp_linpool, 0, EA_BGP_MPLS_LABEL_STACK);
+
+    if (export)
+    {
+      struct mpls_channel *mc = (void *) p->p.mpls_channel;
+      ea_set_attr_u32(&a->eattrs, tmp_linpool, EA_MPLS_POLICY, 0, EAF_TYPE_INT, mc->label_policy);
+
+      struct adata *ad = l3vpn_export_targets(p, ea_get_adata(a0->eattrs, EA_BGP_EXT_COMMUNITY));
+      ea_set_attr_ptr(&a->eattrs, tmp_linpool, EA_BGP_EXT_COMMUNITY, 0, EAF_TYPE_EC_SET, ad);
+
+      /* Replace MPLS-incompatible nexthop with lookup in VRF table */
+      if (!mpls_valid_nexthop(a) && p->p.vrf)
+      {
+	a->dest = RTD_UNICAST;
+	a->nh = (struct nexthop) { .iface = p->p.vrf };
+      }
+    }
+
+    /* Keep original IGP metric as a base for L3VPN metric */
+    if (!export)
+      a->igp_metric = a0->igp_metric;
+
+    rte *e = rte_get_temp(a, src);
+    rte_update2(dst, n, e, src);
+  }
+  else
+  {
+    rte_update2(dst, n, NULL, src);
+  }
+}
+
+
+static int
+l3vpn_preexport(struct channel *C, rte *e)
+{
+  struct l3vpn_proto *p = (void *) C->proto;
+  struct proto *pp = e->sender->proto;
+
+  if (pp == C->proto)
+    return -1;	/* Avoid local loops automatically */
+
+  switch (C->net_type)
+  {
+  case NET_IP4:
+  case NET_IP6:
+    return 0;
+
+  case NET_VPN4:
+  case NET_VPN6:
+    return l3vpn_import_targets(p, ea_get_adata(e->attrs->eattrs, EA_BGP_EXT_COMMUNITY)) ? 0 : -1;
+
+  case NET_MPLS:
+    return -1;
+
+  default:
+    bug("invalid type");
+  }
+}
+
+static void
+l3vpn_reload_routes(struct channel *C)
+{
+  struct l3vpn_proto *p = (void *) C->proto;
+
+  /* Route reload on one channel is just refeed on the other */
+  switch (C->net_type)
+  {
+  case NET_IP4:
+    channel_request_feeding(p->vpn4_channel);
+    break;
+
+  case NET_IP6:
+    channel_request_feeding(p->vpn6_channel);
+    break;
+
+  case NET_VPN4:
+    channel_request_feeding(p->ip4_channel);
+    break;
+
+  case NET_VPN6:
+    channel_request_feeding(p->ip6_channel);
+    break;
+
+  case NET_MPLS:
+    channel_request_feeding(p->ip4_channel);
+    channel_request_feeding(p->ip6_channel);
+    break;
+  }
+}
+
+static inline u32
+l3vpn_metric(rte *e)
+{
+  u32 metric = ea_get_int(e->attrs->eattrs, EA_GEN_IGP_METRIC, e->attrs->igp_metric);
+  return MIN(metric, IGP_METRIC_UNKNOWN);
+}
+
+static int
+l3vpn_rte_better(rte *new, rte *old)
+{
+  /* This is hack, we should have full BGP-style comparison */
+  return l3vpn_metric(new) < l3vpn_metric(old);
+}
+
+static void
+l3vpn_postconfig(struct proto_config *CF)
+{
+  struct l3vpn_config *cf = (void *) CF;
+
+  if (!!proto_cf_find_channel(CF, NET_IP4) != !!proto_cf_find_channel(CF, NET_VPN4))
+    cf_error("For IPv4 L3VPN, both IPv4 and VPNv4 channels must be specified");
+
+  if (!!proto_cf_find_channel(CF, NET_IP6) != !!proto_cf_find_channel(CF, NET_VPN6))
+    cf_error("For IPv6 L3VPN, both IPv6 and VPNv6 channels must be specified");
+
+  if (!proto_cf_find_channel(CF, NET_MPLS))
+    cf_error("MPLS channel not specified");
+
+  if (!cf->rd)
+    cf_error("Route distinguisher not specified");
+
+  if (!cf->import_target && !cf->export_target)
+    cf_error("Route target not specified");
+
+  if (!cf->import_target)
+    cf_error("Import target not specified");
+
+  if (!cf->export_target)
+    cf_error("Export target not specified");
+}
+
+static struct proto *
+l3vpn_init(struct proto_config *CF)
+{
+  struct proto *P = proto_new(CF);
+  struct l3vpn_proto *p = (void *) P;
+  // struct l3vpn_config *cf = (void *) CF;
+
+  proto_configure_channel(P, &p->ip4_channel, proto_cf_find_channel(CF, NET_IP4));
+  proto_configure_channel(P, &p->ip6_channel, proto_cf_find_channel(CF, NET_IP6));
+  proto_configure_channel(P, &p->vpn4_channel, proto_cf_find_channel(CF, NET_VPN4));
+  proto_configure_channel(P, &p->vpn6_channel, proto_cf_find_channel(CF, NET_VPN6));
+  proto_configure_channel(P, &P->mpls_channel, proto_cf_find_channel(CF, NET_MPLS));
+
+  P->rt_notify = l3vpn_rt_notify;
+  P->preexport = l3vpn_preexport;
+  P->reload_routes = l3vpn_reload_routes;
+  P->rte_better = l3vpn_rte_better;
+
+  return P;
+}
+
+static int
+l3vpn_start(struct proto *P)
+{
+  struct l3vpn_proto *p = (void *) P;
+  struct l3vpn_config *cf = (void *) P->cf;
+
+  p->rd = cf->rd;
+  p->import_target = cf->import_target;
+  p->export_target = cf->export_target;
+  p->export_target_data = NULL;
+
+  l3vpn_prepare_import_targets(p);
+  l3vpn_prepare_export_targets(p);
+
+  proto_setup_mpls_map(P, RTS_L3VPN, 1);
+
+  if (P->vrf_set)
+    P->mpls_map->vrf_iface = P->vrf;
+
+  return PS_UP;
+}
+
+static int
+l3vpn_shutdown(struct proto *P)
+{
+  // struct l3vpn_proto *p = (void *) P;
+
+  proto_shutdown_mpls_map(P, 1);
+
+  return PS_DOWN;
+}
+
+static int
+l3vpn_reconfigure(struct proto *P, struct proto_config *CF)
+{
+  struct l3vpn_proto *p = (void *) P;
+  struct l3vpn_config *cf = (void *) CF;
+
+  if (!proto_configure_channel(P, &p->ip4_channel, proto_cf_find_channel(CF, NET_IP4)) ||
+      !proto_configure_channel(P, &p->ip6_channel, proto_cf_find_channel(CF, NET_IP6)) ||
+      !proto_configure_channel(P, &p->vpn4_channel, proto_cf_find_channel(CF, NET_VPN4)) ||
+      !proto_configure_channel(P, &p->vpn6_channel, proto_cf_find_channel(CF, NET_VPN6)) ||
+      !proto_configure_channel(P, &P->mpls_channel, proto_cf_find_channel(CF, NET_MPLS)))
+    return 0;
+
+  if (p->rd != cf->rd)
+    return 0;
+
+  int import_changed = !same_tree(p->import_target, cf->import_target);
+  int export_changed = !same_tree(p->export_target, cf->export_target);
+
+  /* Update pointers to config structures */
+  p->import_target = cf->import_target;
+  p->export_target = cf->export_target;
+
+  proto_setup_mpls_map(P, RTS_L3VPN, 1);
+
+  if (import_changed)
+  {
+    TRACE(D_EVENTS, "Import target changed");
+
+    l3vpn_prepare_import_targets(p);
+
+    if (p->vpn4_channel && (p->vpn4_channel->channel_state == CS_UP))
+      channel_request_feeding(p->vpn4_channel);
+
+    if (p->vpn6_channel && (p->vpn6_channel->channel_state == CS_UP))
+      channel_request_feeding(p->vpn6_channel);
+  }
+
+  if (export_changed)
+  {
+    TRACE(D_EVENTS, "Export target changed");
+
+    l3vpn_prepare_export_targets(p);
+
+    if (p->ip4_channel && (p->ip4_channel->channel_state == CS_UP))
+      channel_request_feeding(p->ip4_channel);
+
+    if (p->ip6_channel && (p->ip6_channel->channel_state == CS_UP))
+      channel_request_feeding(p->ip6_channel);
+  }
+
+  return 1;
+}
+
+static void
+l3vpn_copy_config(struct proto_config *dest UNUSED, struct proto_config *src UNUSED)
+{
+  /* Just a shallow copy, not many items here */
+}
+
+static void
+l3vpn_get_route_info(rte *rte, byte *buf)
+{
+  u32 metric = l3vpn_metric(rte);
+  if (metric < IGP_METRIC_UNKNOWN)
+    bsprintf(buf, " (%u/%u)", rte->attrs->pref, metric);
+  else
+    bsprintf(buf, " (%u/?)", rte->attrs->pref);
+}
+
+
+struct protocol proto_l3vpn = {
+  .name =		"L3VPN",
+  .template =		"l3vpn%d",
+  .class =		PROTOCOL_L3VPN,
+  .channel_mask =	NB_IP | NB_VPN | NB_MPLS,
+  .proto_size =		sizeof(struct l3vpn_proto),
+  .config_size =	sizeof(struct l3vpn_config),
+  .postconfig =		l3vpn_postconfig,
+  .init =		l3vpn_init,
+  .start =		l3vpn_start,
+  .shutdown =		l3vpn_shutdown,
+  .reconfigure =	l3vpn_reconfigure,
+  .copy_config = 	l3vpn_copy_config,
+  .get_route_info =	l3vpn_get_route_info
+};
+
+void
+l3vpn_build(void)
+{
+  proto_build(&proto_l3vpn);
+}