1 files changed, 126 insertions, 0 deletions
diff --git a/src/VBox/NetworkServices/NAT/rtmon_bsd.c b/src/VBox/NetworkServices/NAT/rtmon_bsd.c
new file mode 100644
index 00000000..05bec3da
--- /dev/null
+++ b/src/VBox/NetworkServices/NAT/rtmon_bsd.c
@@ -0,0 +1,126 @@
+/* $Id: rtmon_bsd.c $ */
+/** @file
+ * NAT Network - IPv6 default route monitor for BSD routing sockets.
+ */
+
+/*
+ * Copyright (C) 2013-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+
+#define LOG_GROUP LOG_GROUP_NAT_SERVICE
+
+#include "proxy.h"
+
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <net/if_dl.h>
+#include <net/route.h>
+
+#include <netinet/in.h>
+#include <netinet/ip6.h>
+
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+
+/**
+ * Query IPv6 routing table - BSD routing sockets version.
+ *
+ * We don't actually monitor the routing socket for updates, and
+ * instead query the kernel each time.
+ *
+ * We take a shortcut and don't read the reply to our RTM_GET - if
+ * there's no default IPv6 route, write(2) will fail with ESRCH
+ * synchronously.  In theory it may fail asynchronously and we should
+ * wait for the RTM_GET reply and check rt_msghdr::rtm_errno.
+ *
+ * KAME code in *BSD maintains internally a list of default routers
+ * that it learned from RAs, and installs only one of them into the
+ * routing table (actually, I'm not sure if BSD routing table can
+ * handle multiple routes to the same destination).  One side-effect
+ * of this is that when manually configured route (e.g. teredo) is
+ * deleted, the system will lose its default route even when KAME IPv6
+ * has default router(s) in its internal list.  Next RA will force the
+ * update, though.
+ *
+ * Solaris does expose multiple routes in the routing table and
+ * replies to RTM_GET with "default default".
+ */
+int
+rtmon_get_defaults(void)
+{
+    int rtsock;
+    struct req {
+        struct rt_msghdr rtm;
+        struct sockaddr_in6 dst;
+        struct sockaddr_in6 mask;
+        struct sockaddr_dl ifp;
+    } req;
+    ssize_t nsent;
+
+    rtsock = socket(PF_ROUTE, SOCK_RAW, AF_INET6);
+    if (rtsock < 0) {
+        DPRINTF0(("rtmon: failed to create routing socket\n"));
+        return -1;
+    }
+
+    memset(&req, 0, sizeof(req));
+
+    req.rtm.rtm_type = RTM_GET;
+    req.rtm.rtm_version = RTM_VERSION;
+    req.rtm.rtm_msglen = sizeof(req);
+    req.rtm.rtm_seq = 0x12345;
+
+    req.rtm.rtm_flags = RTF_UP;
+    req.rtm.rtm_addrs = RTA_DST | RTA_NETMASK | RTA_IFP;
+
+    req.dst.sin6_family = AF_INET6;
+#if HAVE_SA_LEN
+    req.dst.sin6_len = sizeof(req.dst);
+#endif
+
+    req.mask.sin6_family = AF_INET6;
+#if HAVE_SA_LEN
+    req.mask.sin6_len = sizeof(req.mask);
+#endif
+
+    req.ifp.sdl_family = AF_LINK;
+#if HAVE_SA_LEN
+    req.ifp.sdl_len = sizeof(req.ifp);
+#endif
+
+    nsent = write(rtsock, &req, req.rtm.rtm_msglen);
+    if (nsent < 0) {
+        if (errno == ESRCH) {
+            /* there's no default route */
+            return 0;
+        }
+        else {
+            DPRINTF0(("rtmon: failed to send RTM_GET\n"));
+            return -1;
+        }
+    }
+
+    return 1;
+}