sd-icmp6-nd: Add Router Solicitation and Advertisement support

Provide functions to bind the ICMPv6 socket to the approriate interface
and set multicast sending and receiving according to RFC 3493, section
5.2. and RFC 3542, sections 3. and 3.3. Filter out all ICMPv6 messages
except Router Advertisements for the socket in question according to
RFC 3542, section 3.2.

Send Router Solicitations to the all routers multicast group as
described in RFC 4861, section 6. and act on the received Router
Advertisments according to section 6.3.7.

Implement a similar API for ICMPv6 handling as is done for DHCPv4 and
DHCPv6.

1 files changed, 131 insertions, 0 deletions

diff --git a/src/libsystemd-network/dhcp6-network.c b/src/libsystemd-network/dhcp6-network.c
new file mode 100644
index 0000000000..53ce23d16c
--- /dev/null
+++ b/src/libsystemd-network/dhcp6-network.c
@@ -0,0 +1,131 @@
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2014 Intel Corporation. All rights reserved.
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <string.h>
+#include <linux/if_packet.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <netinet/ip6.h>
+#include <netinet/icmp6.h>
+#include <netinet/in.h>
+
+#include "socket-util.h"
+
+#include "dhcp6-internal.h"
+
+#define IN6ADDR_ALL_ROUTERS_MULTICAST_INIT \
+        { { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
+              0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 } } }
+
+#define IN6ADDR_ALL_NODES_MULTICAST_INIT \
+        { { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
+              0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 } } }
+
+int dhcp_network_icmp6_bind_router_solicitation(int index)
+{
+        struct icmp6_filter filter = { };
+        struct ipv6_mreq mreq = {
+                .ipv6mr_multiaddr = IN6ADDR_ALL_NODES_MULTICAST_INIT,
+                .ipv6mr_interface = index,
+        };
+        _cleanup_close_ int s = -1;
+        int r, zero = 0, hops = 255;
+
+        s = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK,
+                   IPPROTO_ICMPV6);
+        if (s < 0)
+                return -errno;
+
+        ICMP6_FILTER_SETBLOCKALL(&filter);
+        ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filter);
+        r = setsockopt(s, IPPROTO_ICMPV6, ICMP6_FILTER, &filter,
+                       sizeof(filter));
+        if (r < 0)
+                return -errno;
+
+        /* RFC 3315, section 6.7, bullet point 2 may indicate that an
+           IPV6_PKTINFO socket option also applies for ICMPv6 multicast.
+           Empirical experiments indicates otherwise and therefore an
+           IPV6_MULTICAST_IF socket option is used here instead */
+        r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_IF, &index,
+                       sizeof(index));
+        if (r < 0)
+                return -errno;
+
+        r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &zero,
+                       sizeof(zero));
+        if (r < 0)
+                return -errno;
+
+        r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops,
+                       sizeof(hops));
+        if (r < 0)
+                return -errno;
+
+        r = setsockopt(s, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq,
+                       sizeof(mreq));
+        if (r < 0)
+                return -errno;
+
+        r = s;
+        s = -1;
+        return r;
+}
+
+int dhcp_network_icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr)
+{
+        struct sockaddr_in6 dst = {
+                .sin6_family = AF_INET6,
+                .sin6_addr = IN6ADDR_ALL_ROUTERS_MULTICAST_INIT,
+        };
+        struct {
+                struct nd_router_solicit rs;
+                struct nd_opt_hdr rs_opt;
+                struct ether_addr rs_opt_mac;
+        } _packed_ rs = {
+                .rs.nd_rs_type = ND_ROUTER_SOLICIT,
+        };
+        struct iovec iov[1] = {
+                { &rs, },
+        };
+        struct msghdr msg = {
+                .msg_name = &dst,
+                .msg_namelen = sizeof(dst),
+                .msg_iov = iov,
+                .msg_iovlen = 1,
+        };
+        int r;
+
+        if (ether_addr) {
+                memcpy(&rs.rs_opt_mac, ether_addr, ETH_ALEN);
+                rs.rs_opt.nd_opt_type = ND_OPT_SOURCE_LINKADDR;
+                rs.rs_opt.nd_opt_len = 1;
+                iov[0].iov_len = sizeof(rs);
+        } else
+                iov[0].iov_len = sizeof(rs.rs);
+
+        r = sendmsg(s, &msg, 0);
+        if (r < 0)
+                return -errno;
+
+        return 0;
+}