src/libsystemd-network/icmp6-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright (C) 2014 Intel Corporation. All rights reserved.
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <netinet/icmp6.h>
  22 #include <netinet/in.h>
  23 #include <netinet/ip6.h>
  24 #include <stdio.h>
  25 #include <string.h>
  26 #include <sys/socket.h>
  27 #include <sys/types.h>
  28 #include <unistd.h>
  29 #include <net/if.h>
  30 #include <linux/if_packet.h>
  31
  32 #include "fd-util.h"
  33 #include "icmp6-util.h"
  34 #include "socket-util.h"
  35
  36 #define IN6ADDR_ALL_ROUTERS_MULTICAST_INIT \
  37         { { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  38               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 } } }
  39
  40 #define IN6ADDR_ALL_NODES_MULTICAST_INIT \
  41         { { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  42               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 } } }
  43
  44 int icmp6_bind_router_solicitation(int index) {
  45         struct icmp6_filter filter = { };
  46         struct ipv6_mreq mreq = {
  47                 .ipv6mr_multiaddr = IN6ADDR_ALL_NODES_MULTICAST_INIT,
  48                 .ipv6mr_interface = index,
  49         };
  50         _cleanup_close_ int s = -1;
  51         char ifname[IF_NAMESIZE] = "";
  52         static const int zero = 0, one = 1, hops = 255;
  53         int r;
  54
  55         s = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK, IPPROTO_ICMPV6);
  56         if (s < 0)
  57                 return -errno;
  58
  59         ICMP6_FILTER_SETBLOCKALL(&filter);
  60         ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filter);
  61         r = setsockopt(s, IPPROTO_ICMPV6, ICMP6_FILTER, &filter, sizeof(filter));
  62         if (r < 0)
  63                 return -errno;
  64
  65         /* RFC 3315, section 6.7, bullet point 2 may indicate that an
  66            IPV6_PKTINFO socket option also applies for ICMPv6 multicast.
  67            Empirical experiments indicates otherwise and therefore an
  68            IPV6_MULTICAST_IF socket option is used here instead */
  69         r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_IF, &index, sizeof(index));
  70         if (r < 0)
  71                 return -errno;
  72
  73         r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &zero, sizeof(zero));
  74         if (r < 0)
  75                 return -errno;
  76
  77         r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, sizeof(hops));
  78         if (r < 0)
  79                 return -errno;
  80
  81         r = setsockopt(s, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
  82         if (r < 0)
  83                 return -errno;
  84
  85         r = setsockopt(s, SOL_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
  86         if (r < 0)
  87                 return -errno;
  88
  89         r = setsockopt(s, SOL_SOCKET, SO_TIMESTAMP, &one, sizeof(one));
  90         if (r < 0)
  91                 return -errno;
  92
  93         if (if_indextoname(index, ifname) == 0)
  94                 return -errno;
  95
  96         r = setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
  97         if (r < 0)
  98                 return -errno;
  99
 100         r = s;
 101         s = -1;
 102         return r;
 103 }
 104
 105 int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr) {
 106         struct sockaddr_in6 dst = {
 107                 .sin6_family = AF_INET6,
 108                 .sin6_addr = IN6ADDR_ALL_ROUTERS_MULTICAST_INIT,
 109         };
 110         struct {
 111                 struct nd_router_solicit rs;
 112                 struct nd_opt_hdr rs_opt;
 113                 struct ether_addr rs_opt_mac;
 114         } _packed_ rs = {
 115                 .rs.nd_rs_type = ND_ROUTER_SOLICIT,
 116                 .rs_opt.nd_opt_type = ND_OPT_SOURCE_LINKADDR,
 117                 .rs_opt.nd_opt_len = 1,
 118         };
 119         struct iovec iov = {
 120                 .iov_base = &rs,
 121                 .iov_len = sizeof(rs),
 122         };
 123         struct msghdr msg = {
 124                 .msg_name = &dst,
 125                 .msg_namelen = sizeof(dst),
 126                 .msg_iov = &iov,
 127                 .msg_iovlen = 1,
 128         };
 129         int r;
 130
 131         assert(s >= 0);
 132         assert(ether_addr);
 133
 134         rs.rs_opt_mac = *ether_addr;
 135
 136         r = sendmsg(s, &msg, 0);
 137         if (r < 0)
 138                 return -errno;
 139
 140         return 0;
 141 }