From 0d44a381b14f7375b9fea59cc78381cbb6b3424a Mon Sep 17 00:00:00 2001
From: dmiller <dmiller@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Tue, 26 Jan 2016 04:52:28 +0000
Subject: [PATCH] Fix netmask handling on FreeBSD. Fixes #284

---
 CHANGELOG                        |  4 ++++
 libdnet-stripped/src/addr.c      | 11 ++++++++++-
 libdnet-stripped/src/route-bsd.c |  5 +++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG b/CHANGELOG
index f7595a299..e23b12dc4 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,9 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [GH#284] Fix retrieval of route netmasks on FreeBSD. IPv6 routes were given
+  /32 netmasks regardless of actual netmask configured, resulting in failed
+  routing. Reported by Martin Gysi. [Daniel Miller]
+
 o Use the same ScanProgressMeter for FTP bounce scan (-b) as for the other scan
   types, allowing periodic status updates with --stats-every or keypress
   events.  [Daniel Miller]
diff --git a/libdnet-stripped/src/addr.c b/libdnet-stripped/src/addr.c
index 05a06924e..ee84af4c8 100644
--- a/libdnet-stripped/src/addr.c
+++ b/libdnet-stripped/src/addr.c
@@ -394,8 +394,17 @@ addr_stob(const struct sockaddr *sa, uint16_t *bits)
 
 #ifdef HAVE_SOCKADDR_IN6
 	if (sa->sa_family == AF_INET6) {
-		len = IP6_ADDR_LEN;
 		p = (u_char *)&so->sin6.sin6_addr;
+#ifdef HAVE_SOCKADDR_SA_LEN
+		len = sa->sa_len - ((void *) p - (void *) sa);
+		/* Handles the special case of sa->sa_len == 0. */
+		if (len < 0)
+			len = 0;
+		else if (len > IP6_ADDR_LEN)
+			len = IP6_ADDR_LEN;
+#else
+		len = IP6_ADDR_LEN;
+#endif
 	} else
 #endif
 	{
diff --git a/libdnet-stripped/src/route-bsd.c b/libdnet-stripped/src/route-bsd.c
index 9bc4bb092..7aa2eaf3e 100644
--- a/libdnet-stripped/src/route-bsd.c
+++ b/libdnet-stripped/src/route-bsd.c
@@ -335,8 +335,11 @@ route_loop(route_t *r, route_handler callback, void *arg)
 	 * p. 494, function get_rtaddrs. */
 	for (ret = 0; next < lim; next += rtm->rtm_msglen) {
 		char namebuf[IF_NAMESIZE];
+		sa_family_t sfam;
 		rtm = (struct rt_msghdr *)next;
 		sa = (struct sockaddr *)(rtm + 1);
+		/* peek at address family */
+		sfam = sa->sa_family;
 
 		if (if_indextoname(rtm->rtm_index, namebuf) == NULL)
 			continue;
@@ -362,6 +365,8 @@ route_loop(route_t *r, route_handler callback, void *arg)
 
 		if (rtm->rtm_addrs & RTA_NETMASK) {
 			sa = NEXTSA(sa);
+			/* FreeBSD for IPv6 uses a different AF for netmasks. Force the same one. */
+			sa->sa_family = sfam;
 			if (addr_stob(sa, &entry.route_dst.addr_bits) < 0)
 				continue;
 		}