Cleanup in sysdep KRT code, part 4.

Adding some files that was accidentally removed
(instead of moved) in cleanup part 2.

3 files changed, 1227 insertions, 0 deletions

diff --git a/sysdep/linux/krt-sys.h b/sysdep/linux/krt-sys.h
new file mode 100644
index 00000000..cdee7fe3
--- /dev/null
+++ b/sysdep/linux/krt-sys.h
@@ -0,0 +1,46 @@
+/*
+ *	BIRD -- Linux Kernel Netlink Route Syncer
+ *
+ *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#ifndef _BIRD_KRT_SYS_H_
+#define _BIRD_KRT_SYS_H_
+
+
+/* Kernel interfaces */
+
+struct kif_params {
+};
+
+struct kif_status {
+};
+
+
+static inline void kif_sys_init(struct kif_proto *p UNUSED) { }
+static inline int kif_sys_reconfigure(struct kif_proto *p UNUSED, struct kif_config *n UNUSED, struct kif_config *o UNUSED) { return 1; }
+
+static inline void kif_sys_preconfig(struct config *c UNUSED) { }
+static inline void kif_sys_postconfig(struct kif_config *c UNUSED) { }
+static inline void kif_sys_init_config(struct kif_config *c UNUSED) { }
+static inline void kif_sys_copy_config(struct kif_config *d UNUSED, struct kif_config *s UNUSED) { }
+
+
+/* Kernel routes */
+
+#define NL_NUM_TABLES 256
+
+struct krt_params {
+  int table_id;				/* Kernel table ID we sync with */
+};
+
+struct krt_status {
+};
+
+
+static inline void krt_sys_init(struct krt_proto *p UNUSED) { }
+
+
+#endif
diff --git a/sysdep/linux/netlink.Y b/sysdep/linux/netlink.Y
new file mode 100644
index 00000000..51689ff9
--- /dev/null
+++ b/sysdep/linux/netlink.Y
@@ -0,0 +1,32 @@
+/*
+ *	BIRD -- Linux Netlink Configuration
+ *
+ *	(c) 1999--2000 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+CF_HDR
+
+CF_DECLS
+
+CF_KEYWORDS(ASYNC, KERNEL, TABLE, KRT_PREFSRC, KRT_REALM)
+
+CF_GRAMMAR
+
+CF_ADDTO(kern_proto, kern_proto nl_item ';')
+
+nl_item:
+   KERNEL TABLE expr {
+	if ($3 <= 0 || $3 >= NL_NUM_TABLES)
+	  cf_error("Kernel routing table number out of range");
+	THIS_KRT->sys.table_id = $3;
+   }
+ ;
+
+CF_ADDTO(dynamic_attr, KRT_PREFSRC { $$ = f_new_dynamic_attr(EAF_TYPE_IP_ADDRESS, T_IP, EA_KRT_PREFSRC); })
+CF_ADDTO(dynamic_attr, KRT_REALM { $$ = f_new_dynamic_attr(EAF_TYPE_INT, T_INT, EA_KRT_REALM); })
+
+CF_CODE
+
+CF_END
diff --git a/sysdep/linux/netlink.c b/sysdep/linux/netlink.c
new file mode 100644
index 00000000..eaaf048e
--- /dev/null
+++ b/sysdep/linux/netlink.c
@@ -0,0 +1,1149 @@
+/*
+ *	BIRD -- Linux Netlink Interface
+ *
+ *	(c) 1999--2000 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <errno.h>
+
+#undef LOCAL_DEBUG
+
+#include "nest/bird.h"
+#include "nest/route.h"
+#include "nest/protocol.h"
+#include "nest/iface.h"
+#include "lib/alloca.h"
+#include "lib/timer.h"
+#include "lib/unix.h"
+#include "lib/krt.h"
+#include "lib/socket.h"
+#include "lib/string.h"
+#include "conf/conf.h"
+
+#include <asm/types.h>
+#include <linux/if.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+
+#ifndef MSG_TRUNC			/* Hack: Several versions of glibc miss this one :( */
+#define MSG_TRUNC 0x20
+#endif
+
+#ifndef IFF_LOWER_UP
+#define IFF_LOWER_UP 0x10000
+#endif
+
+/*
+ *	Synchronous Netlink interface
+ */
+
+struct nl_sock
+{
+  int fd;
+  u32 seq;
+  byte *rx_buffer;			/* Receive buffer */
+  struct nlmsghdr *last_hdr;		/* Recently received packet */
+  unsigned int last_size;
+};
+
+#define NL_RX_SIZE 8192
+
+static struct nl_sock nl_scan = {.fd = -1};	/* Netlink socket for synchronous scan */
+static struct nl_sock nl_req  = {.fd = -1};	/* Netlink socket for requests */
+
+static void
+nl_open_sock(struct nl_sock *nl)
+{
+  if (nl->fd < 0)
+    {
+      nl->fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+      if (nl->fd < 0)
+	die("Unable to open rtnetlink socket: %m");
+      nl->seq = now;
+      nl->rx_buffer = xmalloc(NL_RX_SIZE);
+      nl->last_hdr = NULL;
+      nl->last_size = 0;
+    }
+}
+
+static void
+nl_open(void)
+{
+  nl_open_sock(&nl_scan);
+  nl_open_sock(&nl_req);
+}
+
+static void
+nl_send(struct nl_sock *nl, struct nlmsghdr *nh)
+{
+  struct sockaddr_nl sa;
+
+  memset(&sa, 0, sizeof(sa));
+  sa.nl_family = AF_NETLINK;
+  nh->nlmsg_pid = 0;
+  nh->nlmsg_seq = ++(nl->seq);
+  if (sendto(nl->fd, nh, nh->nlmsg_len, 0, (struct sockaddr *)&sa, sizeof(sa)) < 0)
+    die("rtnetlink sendto: %m");
+  nl->last_hdr = NULL;
+}
+
+static void
+nl_request_dump(int cmd)
+{
+  struct {
+    struct nlmsghdr nh;
+    struct rtgenmsg g;
+  } req;
+  req.nh.nlmsg_type = cmd;
+  req.nh.nlmsg_len = sizeof(req);
+  req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+  /* Is it important which PF_* is used for link-level interface scan?
+     It seems that some information is available only when PF_INET is used. */
+  req.g.rtgen_family = (cmd == RTM_GETLINK) ? PF_INET : BIRD_PF;
+  nl_send(&nl_scan, &req.nh);
+}
+
+static struct nlmsghdr *
+nl_get_reply(struct nl_sock *nl)
+{
+  for(;;)
+    {
+      if (!nl->last_hdr)
+	{
+	  struct iovec iov = { nl->rx_buffer, NL_RX_SIZE };
+	  struct sockaddr_nl sa;
+	  struct msghdr m = { (struct sockaddr *) &sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
+	  int x = recvmsg(nl->fd, &m, 0);
+	  if (x < 0)
+	    die("nl_get_reply: %m");
+	  if (sa.nl_pid)		/* It isn't from the kernel */
+	    {
+	      DBG("Non-kernel packet\n");
+	      continue;
+	    }
+	  nl->last_size = x;
+	  nl->last_hdr = (void *) nl->rx_buffer;
+	  if (m.msg_flags & MSG_TRUNC)
+	    bug("nl_get_reply: got truncated reply which should be impossible");
+	}
+      if (NLMSG_OK(nl->last_hdr, nl->last_size))
+	{
+	  struct nlmsghdr *h = nl->last_hdr;
+	  nl->last_hdr = NLMSG_NEXT(h, nl->last_size);
+	  if (h->nlmsg_seq != nl->seq)
+	    {
+	      log(L_WARN "nl_get_reply: Ignoring out of sequence netlink packet (%x != %x)",
+		  h->nlmsg_seq, nl->seq);
+	      continue;
+	    }
+	  return h;
+	}
+      if (nl->last_size)
+	log(L_WARN "nl_get_reply: Found packet remnant of size %d", nl->last_size);
+      nl->last_hdr = NULL;
+    }
+}
+
+static struct rate_limit rl_netlink_err;
+
+static int
+nl_error(struct nlmsghdr *h)
+{
+  struct nlmsgerr *e;
+  int ec;
+
+  if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
+    {
+      log(L_WARN "Netlink: Truncated error message received");
+      return ENOBUFS;
+    }
+  e = (struct nlmsgerr *) NLMSG_DATA(h);
+  ec = -e->error;
+  if (ec)
+    log_rl(&rl_netlink_err, L_WARN "Netlink: %s", strerror(ec));
+  return ec;
+}
+
+static struct nlmsghdr *
+nl_get_scan(void)
+{
+  struct nlmsghdr *h = nl_get_reply(&nl_scan);
+
+  if (h->nlmsg_type == NLMSG_DONE)
+    return NULL;
+  if (h->nlmsg_type == NLMSG_ERROR)
+    {
+      nl_error(h);
+      return NULL;
+    }
+  return h;
+}
+
+static int
+nl_exchange(struct nlmsghdr *pkt)
+{
+  struct nlmsghdr *h;
+
+  nl_send(&nl_req, pkt);
+  for(;;)
+    {
+      h = nl_get_reply(&nl_req);
+      if (h->nlmsg_type == NLMSG_ERROR)
+	break;
+      log(L_WARN "nl_exchange: Unexpected reply received");
+    }
+  return nl_error(h) ? -1 : 0;
+}
+
+/*
+ *	Netlink attributes
+ */
+
+static int nl_attr_len;
+
+static void *
+nl_checkin(struct nlmsghdr *h, int lsize)
+{
+  nl_attr_len = h->nlmsg_len - NLMSG_LENGTH(lsize);
+  if (nl_attr_len < 0)
+    {
+      log(L_ERR "nl_checkin: underrun by %d bytes", -nl_attr_len);
+      return NULL;
+    }
+  return NLMSG_DATA(h);
+}
+
+static int
+nl_parse_attrs(struct rtattr *a, struct rtattr **k, int ksize)
+{
+  int max = ksize / sizeof(struct rtattr *);
+  bzero(k, ksize);
+  while (RTA_OK(a, nl_attr_len))
+    {
+      if (a->rta_type < max)
+	k[a->rta_type] = a;
+      a = RTA_NEXT(a, nl_attr_len);
+    }
+  if (nl_attr_len)
+    {
+      log(L_ERR "nl_parse_attrs: remnant of size %d", nl_attr_len);
+      return 0;
+    }
+  else
+    return 1;
+}
+
+void
+nl_add_attr(struct nlmsghdr *h, unsigned bufsize, unsigned code,
+	    void *data, unsigned dlen)
+{
+  unsigned len = RTA_LENGTH(dlen);
+  unsigned pos = NLMSG_ALIGN(h->nlmsg_len);
+  struct rtattr *a;
+
+  if (pos + len > bufsize)
+    bug("nl_add_attr: packet buffer overflow");
+  a = (struct rtattr *)((char *)h + pos);
+  a->rta_type = code;
+  a->rta_len = len;
+  h->nlmsg_len = pos + len;
+  memcpy(RTA_DATA(a), data, dlen);
+}
+
+static inline void
+nl_add_attr_u32(struct nlmsghdr *h, unsigned bufsize, int code, u32 data)
+{
+  nl_add_attr(h, bufsize, code, &data, 4);
+}
+
+static inline void
+nl_add_attr_ipa(struct nlmsghdr *h, unsigned bufsize, int code, ip_addr ipa)
+{
+  ipa_hton(ipa);
+  nl_add_attr(h, bufsize, code, &ipa, sizeof(ipa));
+}
+
+#define RTNH_SIZE (sizeof(struct rtnexthop) + sizeof(struct rtattr) + sizeof(ip_addr))
+
+static inline void
+add_mpnexthop(char *buf, ip_addr ipa, unsigned iface, unsigned char weight)
+{
+  struct rtnexthop *nh = (void *) buf;
+  struct rtattr *rt = (void *) (buf + sizeof(*nh));
+  nh->rtnh_len = RTNH_SIZE;
+  nh->rtnh_flags = 0;
+  nh->rtnh_hops = weight;
+  nh->rtnh_ifindex = iface;
+  rt->rta_len = sizeof(*rt) + sizeof(ipa);
+  rt->rta_type = RTA_GATEWAY;
+  ipa_hton(ipa);
+  memcpy(buf + sizeof(*nh) + sizeof(*rt), &ipa, sizeof(ipa));
+}
+
+
+static void
+nl_add_multipath(struct nlmsghdr *h, unsigned bufsize, struct mpnh *nh)
+{
+  unsigned len = sizeof(struct rtattr);
+  unsigned pos = NLMSG_ALIGN(h->nlmsg_len);
+  char *buf = (char *)h + pos;
+  struct rtattr *rt = (void *) buf;
+  buf += len;
+  
+  for (; nh; nh = nh->next)
+    {
+      len += RTNH_SIZE;
+      if (pos + len > bufsize)
+	bug("nl_add_multipath: packet buffer overflow");
+
+      add_mpnexthop(buf, nh->gw, nh->iface->index, nh->weight);
+      buf += RTNH_SIZE;
+    }
+
+  rt->rta_type = RTA_MULTIPATH;
+  rt->rta_len = len;
+  h->nlmsg_len = pos + len;
+}
+
+
+static struct mpnh *
+nl_parse_multipath(struct krt_proto *p, struct rtattr *ra)
+{
+  /* Temporary buffer for multicast nexthops */
+  static struct mpnh *nh_buffer;
+  static int nh_buf_size;	/* in number of structures */
+  static int nh_buf_used;
+
+  struct rtattr *a[RTA_CACHEINFO+1];
+  struct rtnexthop *nh = RTA_DATA(ra);
+  struct mpnh *rv, *first, **last;
+  int len = RTA_PAYLOAD(ra);
+
+  first = NULL;
+  last = &first;
+  nh_buf_used = 0;
+
+  while (len)
+    {
+      /* Use RTNH_OK(nh,len) ?? */
+      if ((len < sizeof(*nh)) || (len < nh->rtnh_len))
+	return NULL;
+
+      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 mpnh));
+      }
+      *last = rv = nh_buffer + nh_buf_used++;
+      rv->next = NULL;
+      last = &(rv->next);
+
+      rv->weight = nh->rtnh_hops;
+      rv->iface = if_find_by_index(nh->rtnh_ifindex);
+      if (!rv->iface)
+	return NULL;
+
+      /* Nonexistent RTNH_PAYLOAD ?? */
+      nl_attr_len = nh->rtnh_len - RTNH_LENGTH(0);
+      nl_parse_attrs(RTNH_DATA(nh), a, sizeof(a));
+      if (a[RTA_GATEWAY])
+	{
+	  if (RTA_PAYLOAD(a[RTA_GATEWAY]) != sizeof(ip_addr))
+	    return NULL;
+
+	  memcpy(&rv->gw, RTA_DATA(a[RTA_GATEWAY]), sizeof(ip_addr));
+	  ipa_ntoh(rv->gw);
+
+	  neighbor *ng = neigh_find2(&p->p, &rv->gw, rv->iface,
+				     (nh->rtnh_flags & RTNH_F_ONLINK) ? NEF_ONLINK : 0);
+	  if (!ng || (ng->scope == SCOPE_HOST))
+	    return NULL;
+	}
+      else
+	return NULL;
+
+      len -= NLMSG_ALIGN(nh->rtnh_len);
+      nh = RTNH_NEXT(nh);
+    }
+
+  return first;
+}
+
+
+/*
+ *	Scanning of interfaces
+ */
+
+static void
+nl_parse_link(struct nlmsghdr *h, int scan)
+{
+  struct ifinfomsg *i;
+  struct rtattr *a[IFLA_WIRELESS+1];
+  int new = h->nlmsg_type == RTM_NEWLINK;
+  struct iface f = {};
+  struct iface *ifi;
+  char *name;
+  u32 mtu;
+  unsigned int fl;
+
+  if (!(i = nl_checkin(h, sizeof(*i))) || !nl_parse_attrs(IFLA_RTA(i), a, sizeof(a)))
+    return;
+  if (!a[IFLA_IFNAME] || RTA_PAYLOAD(a[IFLA_IFNAME]) < 2 ||
+      !a[IFLA_MTU] || RTA_PAYLOAD(a[IFLA_MTU]) != 4)
+    {
+      if (scan || !a[IFLA_WIRELESS])
+        log(L_ERR "nl_parse_link: Malformed message received");
+      return;
+    }
+  name = RTA_DATA(a[IFLA_IFNAME]);
+  memcpy(&mtu, RTA_DATA(a[IFLA_MTU]), sizeof(u32));
+
+  ifi = if_find_by_index(i->ifi_index);
+  if (!new)
+    {
+      DBG("KIF: IF%d(%s) goes down\n", i->ifi_index, name);
+      if (!ifi)
+	return;
+
+      if_delete(ifi);
+    }
+  else
+    {
+      DBG("KIF: IF%d(%s) goes up (mtu=%d,flg=%x)\n", i->ifi_index, name, mtu, i->ifi_flags);
+      if (ifi && strncmp(ifi->name, name, sizeof(ifi->name)-1))
+	if_delete(ifi);
+
+      strncpy(f.name, name, sizeof(f.name)-1);
+      f.index = i->ifi_index;
+      f.mtu = mtu;
+
+      fl = i->ifi_flags;
+      if (fl & IFF_UP)
+	f.flags |= IF_ADMIN_UP;
+      if (fl & IFF_LOWER_UP)
+	f.flags |= IF_LINK_UP;
+      if (fl & IFF_LOOPBACK)		/* Loopback */
+	f.flags |= IF_MULTIACCESS | IF_LOOPBACK | IF_IGNORE;
+      else if (fl & IFF_POINTOPOINT)	/* PtP */
+	f.flags |= IF_MULTICAST;
+      else if (fl & IFF_BROADCAST)	/* Broadcast */
+	f.flags |= IF_MULTIACCESS | IF_BROADCAST | IF_MULTICAST;
+      else
+	f.flags |= IF_MULTIACCESS;	/* NBMA */
+      if_update(&f);
+    }
+}
+
+static void
+nl_parse_addr(struct nlmsghdr *h)
+{
+  struct ifaddrmsg *i;
+  struct rtattr *a[IFA_ANYCAST+1];
+  int new = h->nlmsg_type == RTM_NEWADDR;
+  struct ifa ifa;
+  struct iface *ifi;
+  int scope;
+
+  if (!(i = nl_checkin(h, sizeof(*i))) || !nl_parse_attrs(IFA_RTA(i), a, sizeof(a)))
+    return;
+  if (i->ifa_family != BIRD_AF)
+    return;
+  if (!a[IFA_ADDRESS] || RTA_PAYLOAD(a[IFA_ADDRESS]) != sizeof(ip_addr)
+#ifdef IPV6
+      || a[IFA_LOCAL] && RTA_PAYLOAD(a[IFA_LOCAL]) != sizeof(ip_addr)
+#else
+      || !a[IFA_LOCAL] || RTA_PAYLOAD(a[IFA_LOCAL]) != sizeof(ip_addr)
+      || (a[IFA_BROADCAST] && RTA_PAYLOAD(a[IFA_BROADCAST]) != sizeof(ip_addr))
+#endif
+      )
+    {
+      log(L_ERR "nl_parse_addr: Malformed message received");
+      return;
+    }
+
+  ifi = if_find_by_index(i->ifa_index);
+  if (!ifi)
+    {
+      log(L_ERR "KIF: Received address message for unknown interface %d", i->ifa_index);
+      return;
+    }
+
+  bzero(&ifa, sizeof(ifa));
+  ifa.iface = ifi;
+  if (i->ifa_flags & IFA_F_SECONDARY)
+    ifa.flags |= IA_SECONDARY;
+
+  /* IFA_LOCAL can be unset for IPv6 interfaces */
+  memcpy(&ifa.ip, RTA_DATA(a[IFA_LOCAL] ? : a[IFA_ADDRESS]), sizeof(ifa.ip));
+  ipa_ntoh(ifa.ip);
+  ifa.pxlen = i->ifa_prefixlen;
+  if (i->ifa_prefixlen > BITS_PER_IP_ADDRESS)
+    {
+      log(L_ERR "KIF: Invalid prefix length for interface %s: %d", ifi->name, i->ifa_prefixlen);
+      new = 0;
+    }
+  if (i->ifa_prefixlen == BITS_PER_IP_ADDRESS)
+    {
+      ip_addr addr;
+      memcpy(&addr, RTA_DATA(a[IFA_ADDRESS]), sizeof(addr));
+      ipa_ntoh(addr);
+      ifa.prefix = ifa.brd = addr;
+
+      /* It is either a host address or a peer address */
+      if (ipa_equal(ifa.ip, addr))
+	ifa.flags |= IA_HOST;
+      else
+	{
+	  ifa.flags |= IA_PEER;
+	  ifa.opposite = addr;
+	}
+    }
+  else
+    {
+      ip_addr netmask = ipa_mkmask(ifa.pxlen);
+      ifa.prefix = ipa_and(ifa.ip, netmask);
+      ifa.brd = ipa_or(ifa.ip, ipa_not(netmask));
+      if (i->ifa_prefixlen == BITS_PER_IP_ADDRESS - 1)
+	ifa.opposite = ipa_opposite_m1(ifa.ip);
+
+#ifndef IPV6
+      if (i->ifa_prefixlen == BITS_PER_IP_ADDRESS - 2)
+	ifa.opposite = ipa_opposite_m2(ifa.ip);
+
+      if ((ifi->flags & IF_BROADCAST) && a[IFA_BROADCAST])
+	{
+	  ip_addr xbrd;
+	  memcpy(&xbrd, RTA_DATA(a[IFA_BROADCAST]), sizeof(xbrd));
+	  ipa_ntoh(xbrd);
+	  if (ipa_equal(xbrd, ifa.prefix) || ipa_equal(xbrd, ifa.brd))
+	    ifa.brd = xbrd;
+	  else if (ifi->flags & IF_TMP_DOWN) /* Complain only during the first scan */
+	    log(L_ERR "KIF: Invalid broadcast address %I for %s", xbrd, ifi->name);
+	}
+#endif
+    }
+
+  scope = ipa_classify(ifa.ip);
+  if (scope < 0)
+    {
+      log(L_ERR "KIF: Invalid interface address %I for %s", ifa.ip, ifi->name);
+      return;
+    }
+  ifa.scope = scope & IADDR_SCOPE_MASK;
+
+  DBG("KIF: IF%d(%s): %s IPA %I, flg %x, net %I/%d, brd %I, opp %I\n",
+      ifi->index, ifi->name,
+      new ? "added" : "removed",
+      ifa.ip, ifa.flags, ifa.prefix, ifa.pxlen, ifa.brd, ifa.opposite);
+  if (new)
+    ifa_update(&ifa);
+  else
+    ifa_delete(&ifa);
+}
+
+void
+kif_do_scan(struct kif_proto *p UNUSED)
+{
+  struct nlmsghdr *h;
+
+  if_start_update();
+
+  nl_request_dump(RTM_GETLINK);
+  while (h = nl_get_scan())
+    if (h->nlmsg_type == RTM_NEWLINK || h->nlmsg_type == RTM_DELLINK)
+      nl_parse_link(h, 1);
+    else
+      log(L_DEBUG "nl_scan_ifaces: Unknown packet received (type=%d)", h->nlmsg_type);
+
+  nl_request_dump(RTM_GETADDR);
+  while (h = nl_get_scan())
+    if (h->nlmsg_type == RTM_NEWADDR || h->nlmsg_type == RTM_DELADDR)
+      nl_parse_addr(h);
+    else
+      log(L_DEBUG "nl_scan_ifaces: Unknown packet received (type=%d)", h->nlmsg_type);
+
+  if_end_update();
+}
+
+/*
+ *	Routes
+ */
+
+static struct krt_proto *nl_table_map[NL_NUM_TABLES];
+
+int
+krt_capable(rte *e)
+{
+  rta *a = e->attrs;
+
+  if (a->cast != RTC_UNICAST)
+    return 0;
+
+  switch (a->dest)
+    {
+    case RTD_ROUTER:
+    case RTD_DEVICE:
+      if (a->iface == NULL)
+	return 0;
+    case RTD_BLACKHOLE:
+    case RTD_UNREACHABLE:
+    case RTD_PROHIBIT:
+    case RTD_MULTIPATH:
+      break;
+    default:
+      return 0;
+    }
+  return 1;
+}
+
+static inline int
+nh_bufsize(struct mpnh *nh)
+{
+  int rv = 0;
+  for (; nh != NULL; nh = nh->next)
+    rv += RTNH_SIZE;
+  return rv;
+}
+
+static int
+nl_send_route(struct krt_proto *p, rte *e, struct ea_list *eattrs, int new)
+{
+  eattr *ea;
+  net *net = e->net;
+  rta *a = e->attrs;
+  struct {
+    struct nlmsghdr h;
+    struct rtmsg r;
+    char buf[128 + nh_bufsize(a->nexthops)];
+  } r;
+
+  DBG("nl_send_route(%I/%d,new=%d)\n", net->n.prefix, net->n.pxlen, new);
+
+  bzero(&r.h, sizeof(r.h));
+  bzero(&r.r, sizeof(r.r));
+  r.h.nlmsg_type = new ? RTM_NEWROUTE : RTM_DELROUTE;
+  r.h.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
+  r.h.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | (new ? NLM_F_CREATE|NLM_F_EXCL : 0);
+
+  r.r.rtm_family = BIRD_AF;
+  r.r.rtm_dst_len = net->n.pxlen;
+  r.r.rtm_tos = 0;
+  r.r.rtm_table = KRT_CF->sys.table_id;
+  r.r.rtm_protocol = RTPROT_BIRD;
+  r.r.rtm_scope = RT_SCOPE_UNIVERSE;
+  nl_add_attr_ipa(&r.h, sizeof(r), RTA_DST, net->n.prefix);
+
+  u32 metric = 0;
+  if (new && e->attrs->source == RTS_INHERIT)
+    metric = e->u.krt.metric;
+  if (ea = ea_find(eattrs, EA_KRT_METRIC))
+    metric = ea->u.data;
+  if (metric != 0)
+    nl_add_attr_u32(&r.h, sizeof(r), RTA_PRIORITY, metric);
+
+  if (ea = ea_find(eattrs, EA_KRT_PREFSRC))
+    nl_add_attr_ipa(&r.h, sizeof(r), RTA_PREFSRC, *(ip_addr *)ea->u.ptr->data);
+
+  if (ea = ea_find(eattrs, EA_KRT_REALM))
+    nl_add_attr_u32(&r.h, sizeof(r), RTA_FLOW, ea->u.data);
+
+  /* a->iface != NULL checked in krt_capable() for router and device routes */
+
+  switch (a->dest)
+    {
+    case RTD_ROUTER:
+      r.r.rtm_type = RTN_UNICAST;
+      nl_add_attr_u32(&r.h, sizeof(r), RTA_OIF, a->iface->index);
+      nl_add_attr_ipa(&r.h, sizeof(r), RTA_GATEWAY, a->gw);
+      break;
+    case RTD_DEVICE:
+      r.r.rtm_type = RTN_UNICAST;
+      nl_add_attr_u32(&r.h, sizeof(r), RTA_OIF, a->iface->index);
+      break;
+    case RTD_BLACKHOLE:
+      r.r.rtm_type = RTN_BLACKHOLE;
+      break;
+    case RTD_UNREACHABLE:
+      r.r.rtm_type = RTN_UNREACHABLE;
+      break;
+    case RTD_PROHIBIT:
+      r.r.rtm_type = RTN_PROHIBIT;
+      break;
+    case RTD_MULTIPATH:
+      r.r.rtm_type = RTN_UNICAST;
+      nl_add_multipath(&r.h, sizeof(r), a->nexthops);
+      break;
+    default:
+      bug("krt_capable inconsistent with nl_send_route");
+    }
+
+  return nl_exchange(&r.h);
+}
+
+void
+krt_replace_rte(struct krt_proto *p, net *n, rte *new, rte *old, struct ea_list *eattrs)
+{
+  int err = 0;
+
+  /*
+   * NULL for eattr of the old route is a little hack, but we don't
+   * get proper eattrs for old in rt_notify() anyway. NULL means no
+   * extended route attributes and therefore matches if the kernel
+   * route has any of them.
+   */
+
+  if (old)
+    nl_send_route(p, old, NULL, 0);
+
+  if (new)
+    err = nl_send_route(p, new, eattrs, 1);
+
+  if (err < 0)
+    n->n.flags |= KRF_SYNC_ERROR;
+  else
+    n->n.flags &= ~KRF_SYNC_ERROR;
+}
+
+
+#define SKIP(ARG...) do { DBG("KRT: Ignoring route - " ARG); return; } while(0)
+
+static void
+nl_parse_route(struct nlmsghdr *h, int scan)
+{
+  struct krt_proto *p;
+  struct rtmsg *i;
+  struct rtattr *a[RTA_CACHEINFO+1];
+  int new = h->nlmsg_type == RTM_NEWROUTE;
+
+  ip_addr dst = IPA_NONE;
+  u32 oif = ~0;
+  int src;
+
+  if (!(i = nl_checkin(h, sizeof(*i))) || !nl_parse_attrs(RTM_RTA(i), a, sizeof(a)))
+    return;
+  if (i->rtm_family != BIRD_AF)
+    return;
+  if ((a[RTA_DST] && RTA_PAYLOAD(a[RTA_DST]) != sizeof(ip_addr)) ||
+#ifdef IPV6
+      (a[RTA_IIF] && RTA_PAYLOAD(a[RTA_IIF]) != 4) ||
+#endif
+      (a[RTA_OIF] && RTA_PAYLOAD(a[RTA_OIF]) != 4) ||
+      (a[RTA_GATEWAY] && RTA_PAYLOAD(a[RTA_GATEWAY]) != sizeof(ip_addr)) ||
+      (a[RTA_PRIORITY] && RTA_PAYLOAD(a[RTA_PRIORITY]) != 4) ||
+      (a[RTA_PREFSRC] && RTA_PAYLOAD(a[RTA_PREFSRC]) != sizeof(ip_addr)) ||
+      (a[RTA_FLOW] && RTA_PAYLOAD(a[RTA_OIF]) != 4))
+    {
+      log(L_ERR "KRT: Malformed message received");
+      return;
+    }
+
+  if (a[RTA_DST])
+    {
+      memcpy(&dst, RTA_DATA(a[RTA_DST]), sizeof(dst));
+      ipa_ntoh(dst);
+    }
+
+  if (a[RTA_OIF])
+    memcpy(&oif, RTA_DATA(a[RTA_OIF]), sizeof(oif));
+
+  p = nl_table_map[i->rtm_table];	/* Do we know this table? */
+  DBG("KRT: Got %I/%d, type=%d, oif=%d, table=%d, prid=%d, proto=%s\n", dst, i->rtm_dst_len, i->rtm_type, oif, i->rtm_table, i->rtm_protocol, p ? p->p.name : "(none)");
+  if (!p)
+    SKIP("unknown table %d\n", i->rtm_table);
+
+
+#ifdef IPV6
+  if (a[RTA_IIF])
+    SKIP("IIF set\n");
+#else
+  if (i->rtm_tos != 0)			/* We don't support TOS */
+    SKIP("TOS %02x\n", i->rtm_tos);
+#endif
+
+  if (scan && !new)
+    SKIP("RTM_DELROUTE in scan\n");
+
+  int c = ipa_classify_net(dst);
+  if ((c < 0) || !(c & IADDR_HOST) || ((c & IADDR_SCOPE_MASK) <= SCOPE_LINK))
+    SKIP("strange class/scope\n");
+
+  // ignore rtm_scope, it is not a real scope
+  // if (i->rtm_scope != RT_SCOPE_UNIVERSE)
+  //   SKIP("scope %u\n", i->rtm_scope);
+
+  switch (i->rtm_protocol)
+    {
+    case RTPROT_UNSPEC:
+      SKIP("proto unspec\n");
+
+    case RTPROT_REDIRECT:
+      src = KRT_SRC_REDIRECT;
+      break;
+
+    case RTPROT_KERNEL:
+      src = KRT_SRC_KERNEL;
+      return;
+
+    case RTPROT_BIRD:
+      if (!scan)
+	SKIP("echo\n");
+      src = KRT_SRC_BIRD;
+      break;
+
+    case RTPROT_BOOT:
+    default:
+      src = KRT_SRC_ALIEN;
+    }
+
+  net *net = net_get(p->p.table, dst, i->rtm_dst_len);
+
+  rta ra = {
+    .proto = &p->p,
+    .source = RTS_INHERIT,
+    .scope = SCOPE_UNIVERSE,
+    .cast = RTC_UNICAST
+  };
+
+  switch (i->rtm_type)
+    {
+    case RTN_UNICAST:
+
+      if (a[RTA_MULTIPATH])
+	{
+	  ra.dest = RTD_MULTIPATH;
+	  ra.nexthops = nl_parse_multipath(p, a[RTA_MULTIPATH]);
+	  if (!ra.nexthops)
+	    {
+	      log(L_ERR "KRT: Received strange multipath route %I/%d",
+		  net->n.prefix, net->n.pxlen);
+	      return;
+	    }
+	    
+	  break;
+	}
+
+      ra.iface = if_find_by_index(oif);
+      if (!ra.iface)
+	{
+	  log(L_ERR "KRT: Received route %I/%d with unknown ifindex %u",
+	      net->n.prefix, net->n.pxlen, oif);
+	  return;
+	}
+
+      if (a[RTA_GATEWAY])
+	{
+	  neighbor *ng;
+	  ra.dest = RTD_ROUTER;
+	  memcpy(&ra.gw, RTA_DATA(a[RTA_GATEWAY]), sizeof(ra.gw));
+	  ipa_ntoh(ra.gw);
+
+	  /* Silently skip strange 6to4 routes */
+	  if (ipa_in_net(ra.gw, IPA_NONE, 96))
+	    return;
+
+	  ng = neigh_find2(&p->p, &ra.gw, ra.iface,
+			   (i->rtm_flags & RTNH_F_ONLINK) ? NEF_ONLINK : 0);
+	  if (!ng || (ng->scope == SCOPE_HOST))
+	    {
+	      log(L_ERR "KRT: Received route %I/%d with strange next-hop %I",
+		  net->n.prefix, net->n.pxlen, ra.gw);
+	      return;
+	    }
+	}
+      else
+	{
+	  ra.dest = RTD_DEVICE;
+
+	  /*
+	   * In Linux IPv6, 'native' device routes have proto
+	   * RTPROT_BOOT and not RTPROT_KERNEL (which they have in
+	   * IPv4 and which is expected). We cannot distinguish
+	   * 'native' and user defined device routes, so we ignore all
+	   * such device routes and for consistency, we have the same
+	   * behavior in IPv4. Anyway, users should use RTPROT_STATIC
+	   * for their 'alien' routes.
+	   */
+
+	  if (i->rtm_protocol == RTPROT_BOOT)
+	    src = KRT_SRC_KERNEL;
+	}
+
+      break;
+    case RTN_BLACKHOLE:
+      ra.dest = RTD_BLACKHOLE;
+      break;
+    case RTN_UNREACHABLE:
+      ra.dest = RTD_UNREACHABLE;
+      break;
+    case RTN_PROHIBIT:
+      ra.dest = RTD_PROHIBIT;
+      break;
+    /* FIXME: What about RTN_THROW? */
+    default:
+      SKIP("type %d\n", i->rtm_type);
+      return;
+    }
+
+  rte *e = rte_get_temp(&ra);
+  e->net = net;
+  e->u.krt.src = src;
+  e->u.krt.proto = i->rtm_protocol;
+  e->u.krt.type = i->rtm_type;
+
+  if (a[RTA_PRIORITY])
+    memcpy(&e->u.krt.metric, RTA_DATA(a[RTA_PRIORITY]), sizeof(e->u.krt.metric)); 
+  else
+    e->u.krt.metric = 0;
+
+  if (a[RTA_PREFSRC])
+    {
+      ip_addr ps;
+      memcpy(&ps, RTA_DATA(a[RTA_PREFSRC]), sizeof(ps));
+      ipa_ntoh(ps);
+
+      ea_list *ea = alloca(sizeof(ea_list) + sizeof(eattr));
+      ea->next = ra.eattrs;
+      ra.eattrs = ea;
+      ea->flags = EALF_SORTED;
+      ea->count = 1;
+      ea->attrs[0].id = EA_KRT_PREFSRC;
+      ea->attrs[0].flags = 0;
+      ea->attrs[0].type = EAF_TYPE_IP_ADDRESS;
+      ea->attrs[0].u.ptr = alloca(sizeof(struct adata) + sizeof(ps));
+      ea->attrs[0].u.ptr->length = sizeof(ps);
+      memcpy(ea->attrs[0].u.ptr->data, &ps, sizeof(ps));
+    }
+
+  if (a[RTA_FLOW])
+    {
+      ea_list *ea = alloca(sizeof(ea_list) + sizeof(eattr));
+      ea->next = ra.eattrs;
+      ra.eattrs = ea;
+      ea->flags = EALF_SORTED;
+      ea->count = 1;
+      ea->attrs[0].id = EA_KRT_REALM;
+      ea->attrs[0].flags = 0;
+      ea->attrs[0].type = EAF_TYPE_INT;
+      memcpy(&ea->attrs[0].u.data, RTA_DATA(a[RTA_FLOW]), 4);
+    }
+
+  if (scan)
+    krt_got_route(p, e);
+  else
+    krt_got_route_async(p, e, new);
+}
+
+void
+krt_do_scan(struct krt_proto *p UNUSED)	/* CONFIG_ALL_TABLES_AT_ONCE => p is NULL */
+{
+  struct nlmsghdr *h;
+
+  nl_request_dump(RTM_GETROUTE);
+  while (h = nl_get_scan())
+    if (h->nlmsg_type == RTM_NEWROUTE || h->nlmsg_type == RTM_DELROUTE)
+      nl_parse_route(h, 1);
+    else
+      log(L_DEBUG "nl_scan_fire: Unknown packet received (type=%d)", h->nlmsg_type);
+}
+
+/*
+ *	Asynchronous Netlink interface
+ */
+
+static sock *nl_async_sk;		/* BIRD socket for asynchronous notifications */
+static byte *nl_async_rx_buffer;	/* Receive buffer */
+
+static void
+nl_async_msg(struct nlmsghdr *h)
+{
+  switch (h->nlmsg_type)
+    {
+    case RTM_NEWROUTE:
+    case RTM_DELROUTE:
+      DBG("KRT: Received async route notification (%d)\n", h->nlmsg_type);
+      nl_parse_route(h, 0);
+      break;
+    case RTM_NEWLINK:
+    case RTM_DELLINK:
+      DBG("KRT: Received async link notification (%d)\n", h->nlmsg_type);
+      nl_parse_link(h, 0);
+      break;
+    case RTM_NEWADDR:
+    case RTM_DELADDR:
+      DBG("KRT: Received async address notification (%d)\n", h->nlmsg_type);
+      nl_parse_addr(h);
+      break;
+    default:
+      DBG("KRT: Received unknown async notification (%d)\n", h->nlmsg_type);
+    }
+}
+
+static int
+nl_async_hook(sock *sk, int size UNUSED)
+{
+  struct iovec iov = { nl_async_rx_buffer, NL_RX_SIZE };
+  struct sockaddr_nl sa;
+  struct msghdr m = { (struct sockaddr *) &sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
+  struct nlmsghdr *h;
+  int x;
+  unsigned int len;
+
+  x = recvmsg(sk->fd, &m, 0);
+  if (x < 0)
+    {
+      if (errno == ENOBUFS)
+	{
+	  /*
+	   *  Netlink reports some packets have been thrown away.
+	   *  One day we might react to it by asking for route table
+	   *  scan in near future.
+	   */
+	  return 1;	/* More data are likely to be ready */
+	}
+      else if (errno != EWOULDBLOCK)
+	log(L_ERR "Netlink recvmsg: %m");
+      return 0;
+    }
+  if (sa.nl_pid)		/* It isn't from the kernel */
+    {
+      DBG("Non-kernel packet\n");
+      return 1;
+    }
+  h = (void *) nl_async_rx_buffer;
+  len = x;
+  if (m.msg_flags & MSG_TRUNC)
+    {
+      log(L_WARN "Netlink got truncated asynchronous message");
+      return 1;
+    }
+  while (NLMSG_OK(h, len))
+    {
+      nl_async_msg(h);
+      h = NLMSG_NEXT(h, len);
+    }
+  if (len)
+    log(L_WARN "nl_async_hook: Found packet remnant of size %d", len);
+  return 1;
+}
+
+static void
+nl_open_async(void)
+{
+  sock *sk;
+  struct sockaddr_nl sa;
+  int fd;
+  static int nl_open_tried = 0;
+
+  if (nl_open_tried)
+    return;
+  nl_open_tried = 1;
+
+  DBG("KRT: Opening async netlink socket\n");
+
+  fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+  if (fd < 0)
+    {
+      log(L_ERR "Unable to open asynchronous rtnetlink socket: %m");
+      return;
+    }
+
+  bzero(&sa, sizeof(sa));
+  sa.nl_family = AF_NETLINK;
+#ifdef IPV6
+  sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV6_IFADDR | RTMGRP_IPV6_ROUTE;
+#else
+  sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV4_ROUTE;
+#endif
+  if (bind(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
+    {
+      log(L_ERR "Unable to bind asynchronous rtnetlink socket: %m");
+      return;
+    }
+
+  sk = nl_async_sk = sk_new(krt_pool);
+  sk->type = SK_MAGIC;
+  sk->rx_hook = nl_async_hook;
+  sk->fd = fd;
+  if (sk_open(sk))
+    bug("Netlink: sk_open failed");
+
+  if (!nl_async_rx_buffer)
+    nl_async_rx_buffer = xmalloc(NL_RX_SIZE);
+}
+
+/*
+ *	Interface to the UNIX krt module
+ */
+
+static u8 nl_cf_table[(NL_NUM_TABLES+7) / 8];
+
+void
+krt_sys_start(struct krt_proto *p, int first)
+{
+  nl_table_map[KRT_CF->sys.table_id] = p;
+  if (first)
+    {
+      nl_open();
+      nl_open_async();
+    }
+}
+
+void
+krt_sys_shutdown(struct krt_proto *p UNUSED, int last UNUSED)
+{
+}
+
+int
+krt_sys_reconfigure(struct krt_proto *p UNUSED, struct krt_config *n, struct krt_config *o)
+{
+  return n->sys.table_id == o->sys.table_id;
+}
+
+
+void
+krt_sys_preconfig(struct config *c UNUSED)
+{
+  bzero(&nl_cf_table, sizeof(nl_cf_table));
+}
+
+void
+krt_sys_postconfig(struct krt_config *x)
+{
+  int id = x->sys.table_id;
+
+  if (nl_cf_table[id/8] & (1 << (id%8)))
+    cf_error("Multiple kernel syncers defined for table #%d", id);
+  nl_cf_table[id/8] |= (1 << (id%8));
+}
+
+void
+krt_sys_init_config(struct krt_config *cf)
+{
+  cf->sys.table_id = RT_TABLE_MAIN;
+}
+
+void
+krt_sys_copy_config(struct krt_config *d, struct krt_config *s)
+{
+  d->sys.table_id = s->sys.table_id;
+}
+
+
+
+void
+kif_sys_start(struct kif_proto *p UNUSED)
+{
+  nl_open();
+  nl_open_async();
+}
+
+void
+kif_sys_shutdown(struct kif_proto *p UNUSED)
+{
+}