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 <linux/fib_rules.h>
  26
  27 #include "relayd.h"
  28
  29 static struct uloop_fd rtnl_sock;
  30 static unsigned int rtnl_seq, rtnl_dump_seq;
  31 int route_table = 16800;
  32
  33 static void rtnl_flush(void)
  34 {
  35         int fd;
  36
  37         fd = open("/proc/sys/net/ipv4/route/flush", O_WRONLY);
  38         if (fd < 0)
  39                 return;
  40
  41         write(fd, "-1", 2);
  42         close(fd);
  43 }
  44
  45 static void rtnl_route_request(struct relayd_interface *rif, struct relayd_host *host, bool add)
  46 {
  47         static struct {
  48                 struct nlmsghdr nl;
  49                 struct rtmsg rt;
  50                 struct {
  51                         struct rtattr rta;
  52                         uint8_t ipaddr[4];
  53                 } __packed dst;
  54                 struct {
  55                         struct rtattr rta;
  56                         int table;
  57                 } __packed table;
  58                 struct {
  59                         struct rtattr rta;
  60                         int ifindex;
  61                 } __packed dev;
  62         } __packed req = {
  63                 .nl = {
  64                         .nlmsg_len = sizeof(req),
  65                 },
  66                 .rt = {
  67                         .rtm_family = AF_INET,
  68                         .rtm_dst_len = 32,
  69                         .rtm_table = RT_TABLE_MAIN,
  70                 },
  71                 .table.rta = {
  72                         .rta_type = RTA_TABLE,
  73                         .rta_len = sizeof(req.table),
  74                 },
  75                 .dst.rta = {
  76                         .rta_type = RTA_DST,
  77                         .rta_len = sizeof(req.dst),
  78                 },
  79                 .dev.rta = {
  80                         .rta_type = RTA_OIF,
  81                         .rta_len = sizeof(req.dev),
  82                 },
  83         };
  84
  85         memcpy(req.dst.ipaddr, host->ipaddr, sizeof(req.dst.ipaddr));
  86         req.dev.ifindex = host->rif->sll.sll_ifindex;
  87         req.table.table = rif->rt_table;
  88
  89         req.nl.nlmsg_flags = NLM_F_REQUEST;
  90         if (add) {
  91                 req.nl.nlmsg_type = RTM_NEWROUTE;
  92                 req.nl.nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;
  93
  94                 req.rt.rtm_protocol = RTPROT_BOOT;
  95                 req.rt.rtm_scope = RT_SCOPE_LINK;
  96                 req.rt.rtm_type = RTN_UNICAST;
  97         } else {
  98                 req.nl.nlmsg_type = RTM_DELROUTE;
  99                 req.rt.rtm_scope = RT_SCOPE_NOWHERE;
 100         }
 101
 102         send(rtnl_sock.fd, &req, sizeof(req), 0);
 103         rtnl_flush();
 104 }
 105
 106 static void rtnl_rule_request(struct relayd_interface *rif, bool add)
 107 {
 108         static struct {
 109                 struct nlmsghdr nl;
 110                 struct rtmsg rt;
 111                 struct {
 112                         struct rtattr rta;
 113                         int table;
 114                 } __packed table;
 115                 struct {
 116                         struct rtattr rta;
 117                         char ifname[IFNAMSIZ + 1];
 118                 } __packed dev;
 119         } __packed req = {
 120                 .rt = {
 121                         .rtm_family = AF_INET,
 122                         .rtm_table = RT_TABLE_UNSPEC,
 123                         .rtm_scope = RT_SCOPE_UNIVERSE,
 124                         .rtm_protocol = RTPROT_BOOT,
 125                 },
 126                 .table.rta = {
 127                         .rta_type = FRA_TABLE,
 128                         .rta_len = sizeof(req.table),
 129                 },
 130                 .dev.rta = {
 131                         .rta_type = FRA_IFNAME,
 132                 },
 133         };
 134
 135         int padding = sizeof(req.dev.ifname);
 136         padding -= strlen(rif->ifname) + 1;
 137
 138         strcpy(req.dev.ifname, rif->ifname);
 139         req.dev.rta.rta_len = sizeof(req.dev.rta) + strlen(rif->ifname) + 1;
 140         req.table.table = rif->rt_table;
 141         req.nl.nlmsg_len = sizeof(req) - padding;
 142
 143         req.nl.nlmsg_flags = NLM_F_REQUEST;
 144         if (add) {
 145                 req.nl.nlmsg_type = RTM_NEWRULE;
 146                 req.nl.nlmsg_flags |= NLM_F_CREATE | NLM_F_EXCL;
 147
 148                 req.rt.rtm_type = RTN_UNICAST;
 149         } else {
 150                 req.nl.nlmsg_type = RTM_DELRULE;
 151                 req.rt.rtm_type = RTN_UNSPEC;
 152         }
 153
 154         send(rtnl_sock.fd, &req, req.nl.nlmsg_len, 0);
 155         rtnl_flush();
 156 }
 157
 158 void rtnl_route_set(struct relayd_host *host, bool add)
 159 {
 160         struct relayd_interface *rif;
 161
 162         list_for_each_entry(rif, &interfaces, list) {
 163                 if (rif == host->rif)
 164                         continue;
 165
 166                 rtnl_route_request(rif, host, add);
 167         }
 168 }
 169
 170 void relayd_add_interface_routes(struct relayd_interface *rif)
 171 {
 172         rif->rt_table = route_table++;
 173         rtnl_rule_request(rif, true);
 174 }
 175
 176 void relayd_del_interface_routes(struct relayd_interface *rif)
 177 {
 178         rtnl_rule_request(rif, false);
 179 }
 180
 181 #ifndef NDA_RTA
 182 #define NDA_RTA(r) \
 183     ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ndmsg))))
 184 #endif
 185
 186 static void rtnl_parse_newneigh(struct nlmsghdr *h)
 187 {
 188         struct relayd_interface *rif = NULL;
 189         struct ndmsg *r = NLMSG_DATA(h);
 190         const uint8_t *lladdr = NULL;
 191         const uint8_t *ipaddr = NULL;
 192         struct rtattr *rta;
 193         int len;
 194
 195         if (r->ndm_family != AF_INET)
 196                 return;
 197
 198         list_for_each_entry(rif, &interfaces, list) {
 199                 if (rif->sll.sll_ifindex == r->ndm_ifindex)
 200                         goto found_interface;
 201         }
 202         return;
 203
 204 found_interface:
 205         len = h->nlmsg_len - NLMSG_LENGTH(sizeof(*r));
 206         for (rta = NDA_RTA(r); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
 207                 switch(rta->rta_type) {
 208                 case NDA_LLADDR:
 209                         lladdr = RTA_DATA(rta);
 210                         break;
 211                 case NDA_DST:
 212                         ipaddr = RTA_DATA(rta);
 213                         break;
 214                 default:
 215                         break;
 216                 }
 217         }
 218
 219         if (!lladdr || !ipaddr || (r->ndm_state & (NUD_INCOMPLETE|NUD_FAILED)))
 220                 return;
 221
 222         if (!memcmp(lladdr, "\x00\x00\x00\x00\x00\x00", ETH_ALEN))
 223                 return;
 224
 225         DPRINTF(1, "%s: Found ARP cache entry for host "IP_FMT" ("MAC_FMT")\n",
 226                 rif->ifname, IP_BUF(ipaddr), MAC_BUF(lladdr));
 227         relayd_refresh_host(rif, lladdr, ipaddr);
 228 }
 229
 230 static void rtnl_parse_packet(void *data, int len)
 231 {
 232         struct nlmsghdr *h;
 233
 234         for (h = data; NLMSG_OK(h, len); h = NLMSG_NEXT(h, len)) {
 235                 if (h->nlmsg_type == NLMSG_DONE ||
 236                     h->nlmsg_type == NLMSG_ERROR)
 237                         return;
 238
 239                 if (h->nlmsg_seq != rtnl_dump_seq)
 240                         continue;
 241
 242                 if (h->nlmsg_type == RTM_NEWNEIGH)
 243                         rtnl_parse_newneigh(h);
 244         }
 245 }
 246
 247 static void rtnl_cb(struct uloop_fd *fd, unsigned int events)
 248 {
 249         struct sockaddr_nl nladdr;
 250         static uint8_t buf[16384];
 251         struct iovec iov = {
 252                 .iov_base = buf,
 253                 .iov_len = sizeof(buf),
 254         };
 255         struct msghdr msg = {
 256                 .msg_name = &nladdr,
 257                 .msg_namelen = sizeof(nladdr),
 258                 .msg_iov = &iov,
 259                 .msg_iovlen = 1,
 260         };
 261
 262         do {
 263                 int len;
 264
 265                 len = recvmsg(rtnl_sock.fd, &msg, 0);
 266                 if (len < 0) {
 267                         if (errno == EINTR)
 268                                 continue;
 269
 270                         return;
 271                 }
 272
 273                 if (!len)
 274                         break;
 275
 276                 if (nladdr.nl_pid != 0)
 277                         continue;
 278
 279                 rtnl_parse_packet(buf, len);
 280         } while (1);
 281 }
 282
 283 int relayd_rtnl_init(void)
 284 {
 285         struct sockaddr_nl snl_local;
 286         static struct {
 287                 struct nlmsghdr nlh;
 288                 struct rtgenmsg g;
 289         } req = {
 290                 .nlh = {
 291                         .nlmsg_len = sizeof(req),
 292                         .nlmsg_type = RTM_GETNEIGH,
 293                         .nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST,
 294                         .nlmsg_pid = 0,
 295                 },
 296                 .g.rtgen_family = AF_INET,
 297         };
 298
 299         rtnl_sock.fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 300         if (rtnl_sock.fd < 0) {
 301                 perror("socket(AF_NETLINK)");
 302                 return -1;
 303         }
 304
 305         snl_local.nl_family = AF_NETLINK;
 306
 307         if (bind(rtnl_sock.fd, (struct sockaddr *) &snl_local, sizeof(struct sockaddr_nl)) < 0) {
 308                 perror("bind");
 309                 close(rtnl_sock.fd);
 310                 return -1;
 311         }
 312
 313         rtnl_sock.cb = rtnl_cb;
 314         uloop_fd_add(&rtnl_sock, ULOOP_READ | ULOOP_EDGE_TRIGGER);
 315
 316         rtnl_seq = time(NULL);
 317         rtnl_dump_seq = rtnl_seq;
 318         req.nlh.nlmsg_seq = rtnl_seq;
 319         send(rtnl_sock.fd, &req, sizeof(req), 0);
 320
 321         return 0;
 322 }
 323
 324 void relayd_rtnl_done(void)
 325 {
 326         uloop_fd_delete(&rtnl_sock);
 327         close(rtnl_sock.fd);
 328 }