Rewrote the kernel syncer. The old layering was horrible.

The new kernel syncer is cleanly split between generic UNIX module
and OS dependent submodules:

  -  krt.c (the generic part)
  -  krt-iface (low-level functions for interface handling)
  -  krt-scan (low-level functions for routing table scanning)
  -  krt-set (low-level functions for setting of kernel routes)

krt-set and krt-iface are common for all BSD-like Unices, krt-scan is heavily
system dependent (most Unices require /dev/kmem parsing, Linux uses /proc),
Netlink substitues all three modules.

We expect each UNIX port supports kernel routing table scanning, kernel
interface table scanning, kernel route manipulation and possibly also
asynchronous event notifications (new route, interface state change;
not implemented yet) and build the KRT protocol on the top of these
primitive operations.

1 files changed, 291 insertions, 0 deletions

diff --git a/sysdep/unix/krt.c b/sysdep/unix/krt.c
new file mode 100644
index 00000000..d44a57d8
--- /dev/null
+++ b/sysdep/unix/krt.c
@@ -0,0 +1,291 @@
+/*
+ *	BIRD -- UNIX Kernel Synchronization
+ *
+ *	(c) 1998--1999 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#define LOCAL_DEBUG
+
+#include "nest/bird.h"
+#include "nest/iface.h"
+#include "nest/route.h"
+#include "nest/protocol.h"
+#include "lib/timer.h"
+
+#include "unix.h"
+#include "krt.h"
+
+struct proto_config *cf_krt;
+
+/*
+ *	Routes
+ */
+
+static void
+krt_flush_routes(struct krt_proto *p)
+{
+  struct rtable *t = &master_table;
+
+  DBG("Flushing kernel routes...\n");
+  while (t && t->tos)
+    t = t->sibling;
+  if (!t)
+    return;
+  FIB_WALK(&t->fib, f)
+    {
+      net *n = (net *) f;
+      rte *e = n->routes;
+      if (e)
+	{
+	  rta *a = e->attrs;
+	  if (a->source != RTS_DEVICE && a->source != RTS_INHERIT)
+	    krt_set_notify(&p->p, e->net, e, NULL);
+	}
+    }
+  FIB_WALK_END;
+}
+
+/* FIXME: Inbound/outbound route filtering? */
+/* FIXME: Synchronization of multiple routing tables? */
+
+static int
+krt_uptodate(rte *k, rte *e)
+{
+  rta *ka = k->attrs, *ea = e->attrs;
+
+  if (ka->dest != ea->dest)
+    return 0;
+  switch (ka->dest)
+    {
+    case RTD_ROUTER:
+      return ipa_equal(ka->gw, ea->gw);
+    case RTD_DEVICE:
+      return !strcmp(ka->iface->name, ea->iface->name);
+    default:
+      return 1;
+    }
+}
+
+/*
+ *  This gets called back when the low-level scanning code discovers a route.
+ *  We expect that the route is a temporary rte and its attributes are uncached.
+ */
+
+void
+krt_got_route(struct krt_proto *p, rte *e)
+{
+  rte *old;
+  net *net = e->net;
+  int verdict;
+
+  if (net->n.flags)
+    {
+      /* Route to this destination was already seen. Strange, but it happens... */
+      DBG("Already seen.\n");
+      return;
+    }
+
+  old = net->routes;
+  if (old && !krt_capable(old))
+    old = NULL;
+  if (old)
+    {
+      if (krt_uptodate(e, net->routes))
+	verdict = KRF_SEEN;
+      else
+	verdict = KRF_UPDATE;
+    }
+  else if (KRT_CF->learn && !net->routes)
+    verdict = KRF_LEARN;
+  else
+    verdict = KRF_DELETE;
+
+  DBG("krt_parse_entry: verdict=%s\n", ((char *[]) { "CREATE", "SEEN", "UPDATE", "DELETE", "LEARN" }) [verdict]);
+
+  net->n.flags = verdict;
+  if (verdict != KRF_SEEN)
+    {
+      /* Get a cached copy of attributes and link the route */
+      rta *a = e->attrs;
+      a->source = RTS_DUMMY;
+      e->attrs = rta_lookup(a);
+      e->next = net->routes;
+      net->routes = e;
+    }
+  else
+    rte_free(e);
+}
+
+static void
+krt_prune(struct krt_proto *p)
+{
+  struct proto *pp = &p->p;
+  struct rtable *t = &master_table;
+  struct fib_node *f;
+
+  DBG("Pruning routes...\n");
+  while (t && t->tos)
+    t = t->sibling;
+  if (!t)
+    return;
+  FIB_WALK(&t->fib, f)
+    {
+      net *n = (net *) f;
+      int verdict = f->flags;
+      rte *new, *old;
+
+      if (verdict != KRF_CREATE && verdict != KRF_SEEN)
+	{
+	  old = n->routes;
+	  n->routes = old->next;
+	}
+      else
+	old = NULL;
+      new = n->routes;
+
+      switch (verdict)
+	{
+	case KRF_CREATE:
+	  if (new)
+	    {
+	      if (new->attrs->source == RTS_INHERIT)
+		{
+		  DBG("krt_prune: removing inherited %I/%d\n", n->n.prefix, n->n.pxlen);
+		  rte_update(n, pp, NULL);
+		}
+	      else
+		{
+		  DBG("krt_prune: reinstalling %I/%d\n", n->n.prefix, n->n.pxlen);
+		  krt_set_notify(pp, n, new, NULL);
+		}
+	    }
+	  break;
+	case KRF_SEEN:
+	  /* Nothing happens */
+	  break;
+	case KRF_UPDATE:
+	  DBG("krt_prune: updating %I/%d\n", n->n.prefix, n->n.pxlen);
+	  krt_set_notify(pp, n, new, old);
+	  break;
+	case KRF_DELETE:
+	  DBG("krt_prune: deleting %I/%d\n", n->n.prefix, n->n.pxlen);
+	  krt_set_notify(pp, n, NULL, old);
+	  break;
+	case KRF_LEARN:
+	  DBG("krt_prune: learning %I/%d\n", n->n.prefix, n->n.pxlen);
+	  rte_update(n, pp, new);
+	  break;
+	default:
+	  bug("krt_prune: invalid route status");
+	}
+
+      if (old)
+	rte_free(old);
+      f->flags = 0;
+    }
+  FIB_WALK_END;
+}
+
+/*
+ *	Periodic scanning
+ */
+
+static timer *krt_scan_timer;
+
+static void
+krt_scan(timer *t)
+{
+  struct krt_proto *p = t->data;
+
+  DBG("KRT: It's scan time...\n");
+  krt_if_scan(p);
+
+  p->accum_time += KRT_CF->scan_time;
+  if (KRT_CF->route_scan_time && p->accum_time >= KRT_CF->route_scan_time)
+    {
+      p->accum_time %= KRT_CF->route_scan_time;
+      DBG("Scanning kernel routing table...\n");
+      krt_scan_fire(p);
+      krt_prune(p);
+    }
+}
+
+/*
+ *	Protocol glue
+ */
+
+static int
+krt_start(struct proto *P)
+{
+  struct krt_proto *p = (struct krt_proto *) P;
+
+  p->accum_time = 0;
+
+  krt_if_start(p);
+  krt_scan_start(p);
+  krt_set_start(p);
+
+  /* Start periodic interface scanning */
+  krt_scan_timer = tm_new(P->pool);
+  krt_scan_timer->hook = krt_scan;
+  krt_scan_timer->data = p;
+  krt_scan_timer->recurrent = KRT_CF->scan_time;
+  krt_scan(krt_scan_timer);
+  tm_start(krt_scan_timer, KRT_CF->scan_time);
+
+  return PS_UP;
+}
+
+int
+krt_shutdown(struct proto *P)
+{
+  struct krt_proto *p = (struct krt_proto *) P;
+
+  if (!KRT_CF->persist)
+    krt_flush_routes(p);
+
+  krt_set_shutdown(p);
+  krt_scan_shutdown(p);
+
+  /* Stop periodic interface scans */
+  tm_stop(krt_scan_timer);
+  krt_if_shutdown(p);
+  /* FIXME: What should we do with interfaces? */
+
+  return PS_DOWN;
+}
+
+static void
+krt_preconfig(struct protocol *x, struct config *c)
+{
+  struct krt_config *z = proto_config_new(&proto_unix_kernel, sizeof(struct krt_config));
+
+  cf_krt = &z->c;
+  z->c.preference = DEF_PREF_UKR;
+  z->scan_time = z->route_scan_time = 60;
+  z->learn = z->persist = 0;
+
+  krt_scan_preconfig(z);
+  krt_set_preconfig(z);
+  krt_if_preconfig(z);
+}
+
+static struct proto *
+krt_init(struct proto_config *c)
+{
+  struct krt_proto *p = proto_new(c, sizeof(struct krt_proto));
+
+  p->p.rt_notify = krt_set_notify;
+  return &p->p;
+}
+
+struct protocol proto_unix_kernel = {
+  name:		"Kernel",
+  priority:	90,
+  preconfig:	krt_preconfig,
+  init:		krt_init,
+  start:	krt_start,
+  shutdown:	krt_shutdown,
+};