route.c

   1 /*
   2  *   Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
   3  *
   4  *   This program is free software; you can redistribute it and/or modify
   5  *   it under the terms of the GNU General Public License v2 as published by
   6  *   the Free Software Foundation.
   7  *
   8  *   This program is distributed in the hope that it will be useful,
   9  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  *   GNU General Public License for more details.
  12  *
  13  *   You should have received a copy of the GNU General Public License
  14  *   along with this program; if not, write to the Free Software
  15  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  16  */
  17
  18 #include <sys/socket.h>
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <errno.h>
  22 #include <unistd.h>
  23 #include <fcntl.h>
  24
  25 #include "relayd.h"
  26
  27 static struct uloop_fd rtnl_sock;
  28 static unsigned int rtnl_seq, rtnl_dump_seq;
  29
  30 static void rtnl_flush(void)
  31 {
  32         int fd;
  33
  34         fd = open("/proc/sys/net/ipv4/route/flush", O_WRONLY);
  35         if (fd < 0)
  36                 return;
  37
  38         write(fd, "-1", 2);
  39         close(fd);
  40 }
  41
  42 static void rtnl_route_set(struct relayd_host *host, bool add)
  43 {
  44         static struct {
  45                 struct nlmsghdr nl;
  46                 struct rtmsg rt;
  47                 struct {
  48                         struct rtattr rta;
  49                         uint8_t ipaddr[4];
  50                 } __packed dst;
  51                 struct {
  52                         struct rtattr rta;
  53                         int ifindex;
  54                 } __packed dev;
  55         } __packed req;
  56
  57         memset(&req, 0, sizeof(req));
  58
  59         req.nl.nlmsg_len = sizeof(req);
  60         req.rt.rtm_family = AF_INET;
  61         req.rt.rtm_dst_len = 32;
  62
  63         req.dst.rta.rta_type = RTA_DST;
  64         req.dst.rta.rta_len = sizeof(req.dst);
  65         memcpy(req.dst.ipaddr, host->ipaddr, sizeof(req.dst.ipaddr));
  66
  67         req.dev.rta.rta_type = RTA_OIF;
  68         req.dev.rta.rta_len = sizeof(req.dev);
  69         req.dev.ifindex = host->rif->sll.sll_ifindex;
  70
  71         req.nl.nlmsg_flags = NLM_F_REQUEST;
  72         req.rt.rtm_table = RT_TABLE_MAIN;
  73         if (add) {
  74                 req.nl.nlmsg_type = RTM_NEWROUTE;
  75                 req.nl.nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
  76
  77                 req.rt.rtm_protocol = RTPROT_BOOT;
  78                 req.rt.rtm_scope = RT_SCOPE_LINK;
  79                 req.rt.rtm_type = RTN_UNICAST;
  80         } else {
  81                 req.nl.nlmsg_type = RTM_DELROUTE;
  82                 req.rt.rtm_scope = RT_SCOPE_NOWHERE;
  83         }
  84
  85         send(rtnl_sock.fd, &req, sizeof(req), 0);
  86         rtnl_flush();
  87 }
  88
  89 void relayd_add_route(struct relayd_host *host)
  90 {
  91         rtnl_route_set(host, true);
  92 }
  93
  94 void relayd_del_route(struct relayd_host *host)
  95 {
  96         rtnl_route_set(host, false);
  97 }
  98
  99 #ifndef NDA_RTA
 100 #define NDA_RTA(r) \
 101     ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ndmsg))))
 102 #endif
 103
 104 static void rtnl_parse_newneigh(struct nlmsghdr *h)
 105 {
 106         struct relayd_interface *rif = NULL;
 107         struct ndmsg *r = NLMSG_DATA(h);
 108         const uint8_t *lladdr = NULL;
 109         const uint8_t *ipaddr = NULL;
 110         struct rtattr *rta;
 111         int len;
 112
 113         if (r->ndm_family != AF_INET)
 114                 return;
 115
 116         list_for_each_entry(rif, &interfaces, list) {
 117                 if (rif->sll.sll_ifindex == r->ndm_ifindex)
 118                         goto found_interface;
 119         }
 120         return;
 121
 122 found_interface:
 123         len = h->nlmsg_len - NLMSG_LENGTH(sizeof(*r));
 124         for (rta = NDA_RTA(r); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
 125                 switch(rta->rta_type) {
 126                 case NDA_LLADDR:
 127                         lladdr = RTA_DATA(rta);
 128                         break;
 129                 case NDA_DST:
 130                         ipaddr = RTA_DATA(rta);
 131                         break;
 132                 default:
 133                         break;
 134                 }
 135         }
 136
 137         if (!lladdr || !ipaddr || (r->ndm_state & (NUD_INCOMPLETE|NUD_FAILED)))
 138                 return;
 139
 140         if (!memcmp(lladdr, "\x00\x00\x00\x00\x00\x00", ETH_ALEN))
 141                 return;
 142
 143         DPRINTF(1, "%s: Found ARP cache entry for host "IP_FMT" ("MAC_FMT")\n",
 144                 rif->ifname, IP_BUF(ipaddr), MAC_BUF(lladdr));
 145         relayd_refresh_host(rif, lladdr, ipaddr);
 146 }
 147
 148 static void rtnl_parse_packet(void *data, int len)
 149 {
 150         struct nlmsghdr *h;
 151
 152         for (h = data; NLMSG_OK(h, len); h = NLMSG_NEXT(h, len)) {
 153                 if (h->nlmsg_type == NLMSG_DONE ||
 154                     h->nlmsg_type == NLMSG_ERROR)
 155                         return;
 156
 157                 if (h->nlmsg_seq != rtnl_dump_seq)
 158                         continue;
 159
 160                 if (h->nlmsg_type == RTM_NEWNEIGH)
 161                         rtnl_parse_newneigh(h);
 162         }
 163 }
 164
 165 static void rtnl_cb(struct uloop_fd *fd, unsigned int events)
 166 {
 167         struct sockaddr_nl nladdr;
 168         static uint8_t buf[16384];
 169         struct iovec iov = {
 170                 .iov_base = buf,
 171                 .iov_len = sizeof(buf),
 172         };
 173         struct msghdr msg = {
 174                 .msg_name = &nladdr,
 175                 .msg_namelen = sizeof(nladdr),
 176                 .msg_iov = &iov,
 177                 .msg_iovlen = 1,
 178         };
 179
 180         do {
 181                 int len;
 182
 183                 len = recvmsg(rtnl_sock.fd, &msg, 0);
 184                 if (len < 0) {
 185                         if (errno == EINTR)
 186                                 continue;
 187
 188                         return;
 189                 }
 190
 191                 if (!len)
 192                         break;
 193
 194                 if (nladdr.nl_pid != 0)
 195                         continue;
 196
 197                 rtnl_parse_packet(buf, len);
 198         } while (1);
 199 }
 200
 201 int relayd_rtnl_init(void)
 202 {
 203         struct sockaddr_nl snl_local;
 204         static struct {
 205                 struct nlmsghdr nlh;
 206                 struct rtgenmsg g;
 207         } req = {
 208                 .nlh = {
 209                         .nlmsg_len = sizeof(req),
 210                         .nlmsg_type = RTM_GETNEIGH,
 211                         .nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST,
 212                         .nlmsg_pid = 0,
 213                 },
 214                 .g.rtgen_family = AF_INET,
 215         };
 216
 217         rtnl_sock.fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 218         if (rtnl_sock.fd < 0) {
 219                 perror("socket(AF_NETLINK)");
 220                 return -1;
 221         }
 222
 223         snl_local.nl_family = AF_NETLINK;
 224
 225         if (bind(rtnl_sock.fd, (struct sockaddr *) &snl_local, sizeof(struct sockaddr_nl)) < 0) {
 226                 perror("bind");
 227                 close(rtnl_sock.fd);
 228                 return -1;
 229         }
 230
 231         rtnl_sock.cb = rtnl_cb;
 232         uloop_fd_add(&rtnl_sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 233
 234         rtnl_seq = time(NULL);
 235         rtnl_dump_seq = rtnl_seq;
 236         req.nlh.nlmsg_seq = rtnl_seq;
 237         send(rtnl_sock.fd, &req, sizeof(req), 0);
 238
 239         return 0;
 240 }
 241
 242 void relayd_rtnl_done(void)
 243 {
 244         uloop_fd_delete(&rtnl_sock);
 245         close(rtnl_sock.fd);
 246 }