Implemented scanning of network interfaces. Mostly very ugly code due to

terrible kernel interface (SIOGIFCONF and friends).

1 files changed, 178 insertions, 0 deletions

diff --git a/sysdep/unix/sync-if.c b/sysdep/unix/sync-if.c
new file mode 100644
index 0000000..742421f
--- /dev/null
+++ b/sysdep/unix/sync-if.c
@@ -0,0 +1,178 @@
+/*
+ *	BIRD -- Unix Interface Scanning and Syncing
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#include <string.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <errno.h>
+
+#define LOCAL_DEBUG
+
+#include "nest/bird.h"
+#include "nest/iface.h"
+#include "lib/timer.h"
+
+#include "unix.h"
+
+int if_scan_sock;
+int if_scan_period = 60;
+
+static timer *if_scan_timer;
+
+static void
+scan_ifs(struct ifreq *r, int cnt)
+{
+  struct iface i;
+  struct ifa a;
+  char *err;
+  unsigned fl;
+  ip_addr netmask;
+  int l;
+
+  for (cnt /= sizeof(struct ifreq); cnt; cnt--, r++)
+    {
+      bzero(&i, sizeof(i));
+      bzero(&a, sizeof(a));
+      debug("%s\n", r->ifr_ifrn.ifrn_name);
+      strncpy(i.name, r->ifr_ifrn.ifrn_name, sizeof(i.name) - 1);
+      i.name[sizeof(i.name) - 1] = 0;
+      i.ifa = &a;
+      get_sockaddr((struct sockaddr_in *) &r->ifr_addr, &a.ip, NULL);
+      l = ipa_classify(a.ip);
+      if (l < 0 || !(l & IADDR_HOST))
+	{
+	  log(L_ERR "%s: Invalid interface address", i.name);
+	  goto bad;
+	}
+      if ((l & IADDR_SCOPE_MASK) == SCOPE_HOST)
+	i.flags |= IF_LOOPBACK | IF_IGNORE;
+
+      if (ioctl(if_scan_sock, SIOCGIFFLAGS, r) < 0)
+	{
+	  err = "SIOCGIFFLAGS";
+	faulty:
+	  log(L_ERR "%s(%s): %m", err, i.name);
+	bad:
+	  i.flags = (i.flags & ~IF_UP) | IF_ADMIN_DOWN;
+	  continue;
+	}
+      fl = r->ifr_flags;
+      if (fl & IFF_UP)
+	i.flags |= IF_UP;
+
+      if (ioctl(if_scan_sock, SIOCGIFNETMASK, r) < 0)
+	{ err = "SIOCGIFNETMASK"; goto faulty; }
+      get_sockaddr((struct sockaddr_in *) &r->ifr_addr, &netmask, NULL);
+      l = ipa_mklen(netmask);
+      if (l < 0 || l == 31)
+	{
+	  log(L_ERR "%s: Invalid netmask", i.name);
+	  goto bad;
+	}
+      a.pxlen = l;
+
+      if (fl & IFF_POINTOPOINT)
+	{
+	  i.flags |= IF_UNNUMBERED;
+	  a.pxlen = BITS_PER_IP_ADDRESS;
+	  if (ioctl(if_scan_sock, SIOCGIFDSTADDR, r) < 0)
+	    { err = "SIOCGIFDSTADDR"; goto faulty; }
+	  get_sockaddr((struct sockaddr_in *) &r->ifr_addr, &a.opposite, NULL);
+	}
+      if (fl & IFF_LOOPBACK)
+	i.flags |= IF_LOOPBACK | IF_IGNORE;
+#ifndef CONFIG_ALL_MULTICAST
+      if (fl & IFF_MULTICAST)
+#endif
+	i.flags |= IF_MULTICAST;
+
+      a.prefix = ipa_and(a.ip, ipa_mkmask(a.pxlen));
+      if (a.pxlen < 32)
+	{
+	  a.brd = ipa_or(a.prefix, ipa_not(ipa_mkmask(a.pxlen)));
+	  if (ipa_equal(a.ip, a.prefix) || ipa_equal(a.ip, a.brd))
+	    {
+	      log(L_ERR "%s: Using network or broadcast address for interface", i.name);
+	      goto bad;
+	    }
+	  if (fl & IFF_BROADCAST)
+	    i.flags |= IF_BROADCAST;
+	  if (a.pxlen < 30)
+	    i.flags |= IF_MULTIACCESS;
+	  else
+	    a.opposite = ipa_opposite(a.ip);
+	}
+      else
+	a.brd = a.opposite;
+
+      if (ioctl(if_scan_sock, SIOCGIFMTU, r) < 0)
+	{ err = "SIOCGIFMTU"; goto faulty; }
+      i.mtu = r->ifr_mtu;
+
+#ifdef SIOCGIFINDEX
+      if (ioctl(if_scan_sock, SIOCGIFINDEX, r) < 0)
+	{ err = "SIOCGIFINDEX"; goto faulty; }
+      i.index = r->ifr_ifindex;
+#endif
+
+      if_update(&i);
+    }
+}
+
+static void
+scan_if(timer *t)
+{
+  struct ifconf ic;
+  static int last_ifbuf_size;
+  int res;
+
+  DBG("Scanning interfaces...\n");
+  for(;;)
+    {
+      if (last_ifbuf_size)
+	{
+	  struct ifreq *r = alloca(last_ifbuf_size);
+	  ic.ifc_ifcu.ifcu_req = r;
+	  ic.ifc_len = last_ifbuf_size;
+	  res = ioctl(if_scan_sock, SIOCGIFCONF, &ic);
+	  if (res < 0 && errno != EFAULT)
+	    die("SIOCCGIFCONF: %m");
+	  if (res < last_ifbuf_size)
+	    {
+	      scan_ifs(r, ic.ifc_len);
+	      break;
+	    }
+	}
+      ic.ifc_ifcu.ifcu_req = NULL;
+      if (ioctl(if_scan_sock, SIOCGIFCONF, &ic) < 0)
+	die("SIOCIFCONF: %m");
+      ic.ifc_len += sizeof(struct ifreq);
+      if (last_ifbuf_size < ic.ifc_len)
+	{
+	  last_ifbuf_size = ic.ifc_len;
+	  DBG("Increased ifconf buffer size to %d\n", last_ifbuf_size);
+	}
+    }
+}
+
+void
+scan_if_init(void)
+{
+  if_scan_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+  DBG("Using socket %d for interface and route scanning\n", if_scan_sock);
+  if (if_scan_sock < 0)
+    die("Cannot create scanning socket: %m");
+  scan_if(NULL);
+  if_scan_timer = tm_new(&root_pool);
+  if_scan_timer->hook = scan_if;
+  if_scan_timer->recurrent = if_scan_period;
+  tm_start(if_scan_timer, if_scan_period);
+}
+