fix ospf segfault introduced in 0.99.19, backported from 0.99.20

net/quagga/Makefile

@@ -1,8 +1,9 @@
-# $OpenBSD: Makefile,v 1.21 2011/09/27 09:45:53 sthen Exp $
+# $OpenBSD: Makefile,v 1.22 2011/10/02 02:01:07 sthen Exp $
 
 COMMENT=	multi-threaded routing daemon
 
 DISTNAME=	quagga-0.99.19
+REVISION=	0
 SHARED_LIBS=	ospf		0.0 \
 		ospfapiclient	0.0 \
 		zebra		0.0

net/quagga/patches/patch-ospfd_ospf_packet_c

@@ -0,0 +1,46 @@
+$OpenBSD: patch-ospfd_ospf_packet_c,v 1.3 2011/10/02 02:01:07 sthen Exp $
+
+from 0.99.20 upstream
+
+--- ospfd/ospf_packet.c.orig	Sun Oct  2 02:44:04 2011
++++ ospfd/ospf_packet.c	Sun Oct  2 02:50:36 2011
+@@ -2455,16 +2455,10 @@ ospf_read (struct thread *thread)
+   /* associate packet with ospf interface */
+   oi = ospf_if_lookup_recv_if (ospf, iph->ip_src, ifp);
+
+-  /* Verify header fields before any further processing. */
+-  ret = ospf_verify_header (ibuf, oi, iph, ospfh);
+-  if (ret < 0)
+-  {
+-    if (IS_DEBUG_OSPF_PACKET (0, RECV))
+-      zlog_debug ("ospf_read[%s]: Header check failed, "
+-                  "dropping.",
+-                  inet_ntoa (iph->ip_src));
+-    return ret;
+-  }
++  /* ospf_verify_header() relies on a valid "oi" and thus can be called only
++     after the passive/backbone/other checks below are passed. These checks
++     in turn access the fields of unverified "ospfh" structure for their own
++     purposes and must remain very accurate in doing this. */
+
+   /* If incoming interface is passive one, ignore it. */
+   if (oi && OSPF_IF_PASSIVE_STATUS (oi) == OSPF_IF_PASSIVE)
+@@ -2555,6 +2549,18 @@ ospf_read (struct thread *thread)
+       ospf_if_set_multicast(oi);
+       return 0;
+     }
++
++  /* Verify more OSPF header fields. */
++  ret = ospf_verify_header (ibuf, oi, iph, ospfh);
++  if (ret < 0)
++  {
++    if (IS_DEBUG_OSPF_PACKET (0, RECV))
++      zlog_debug ("ospf_read[%s]: Header check failed, "
++                  "dropping.",
++                  inet_ntoa (iph->ip_src));
++    return ret;
++  }
++
+
+   /* Show debug receiving packet. */
+   if (IS_DEBUG_OSPF_PACKET (ospfh->type - 1, RECV))