mdw@git.distorted.org.uk Git - secnet/blob - tun.c

   1 #include "secnet.h"
   2 #include "util.h"
   3 #include "netlink.h"
   4 #include <stdio.h>
   5 #include <string.h>
   6 #include <unistd.h>
   7 #include <fcntl.h>
   8 #include <sys/ioctl.h>
   9 #include <sys/utsname.h>
  10 #include <sys/socket.h>
  11
  12 #ifdef HAVE_NET_IF_H
  13 #include <net/if.h>
  14 #ifdef HAVE_LINUX_IF_H
  15 #include <linux/if_tun.h>
  16 #define LINUX_TUN_SUPPORTED
  17 #endif
  18 #endif
  19
  20 #ifdef HAVE_NET_ROUTE_H
  21 #include <net/route.h>
  22 #endif
  23
  24 #if defined(HAVE_STROPTS_H) && defined(HAVE_SYS_SOCKIO_H) && \
  25 defined(HAVE_NET_IF_TUN_H)
  26 #define HAVE_TUN_STREAMS
  27 #endif
  28
  29 #ifdef HAVE_TUN_STREAMS
  30 #include <stropts.h>
  31 #include <sys/sockio.h>
  32 #include <net/if_tun.h>
  33 #endif
  34
  35 #define TUN_FLAVOUR_GUESS   0
  36 #define TUN_FLAVOUR_BSD     1
  37 #define TUN_FLAVOUR_LINUX   2
  38 #define TUN_FLAVOUR_STREAMS 3
  39
  40 static struct flagstr flavours[]={
  41     {"guess", TUN_FLAVOUR_GUESS},
  42     {"bsd", TUN_FLAVOUR_BSD},
  43     {"BSD", TUN_FLAVOUR_BSD},
  44     {"linux", TUN_FLAVOUR_LINUX},
  45     {"streams", TUN_FLAVOUR_STREAMS},
  46     {"STREAMS", TUN_FLAVOUR_STREAMS},
  47     {NULL, 0}
  48 };
  49
  50 #define TUN_CONFIG_GUESS      0
  51 #define TUN_CONFIG_IOCTL      1
  52 #define TUN_CONFIG_BSD        2
  53 #define TUN_CONFIG_LINUX      3
  54 #define TUN_CONFIG_SOLARIS25  4
  55
  56 static struct flagstr config_types[]={
  57     {"guess", TUN_CONFIG_GUESS},
  58     {"ioctl", TUN_CONFIG_IOCTL},
  59     {"bsd", TUN_CONFIG_BSD},
  60     {"BSD", TUN_CONFIG_BSD},
  61     {"linux", TUN_CONFIG_LINUX},
  62     {"solaris-2.5", TUN_CONFIG_SOLARIS25},
  63     {NULL, 0}
  64 };
  65
  66 /* Connection to the kernel through the universal TUN/TAP driver */
  67
  68 struct tun {
  69     struct netlink nl;
  70     int fd;
  71     cstring_t device_path;
  72     cstring_t ip_path;
  73     string_t interface_name;
  74     cstring_t ifconfig_path;
  75     uint32_t ifconfig_type;
  76     cstring_t route_path;
  77     uint32_t route_type;
  78     uint32_t tun_flavour;
  79     bool_t search_for_if; /* Applies to tun-BSD only */
  80     struct buffer_if *buff; /* We receive packets into here
  81                                and send them to the netlink code. */
  82     netlink_deliver_fn *netlink_to_tunnel;
  83     uint32_t local_address; /* host interface address */
  84 };
  85
  86 static cstring_t tun_flavour_str(uint32_t flavour)
  87 {
  88     switch (flavour) {
  89     case TUN_FLAVOUR_GUESS: return "guess";
  90     case TUN_FLAVOUR_BSD: return "BSD";
  91     case TUN_FLAVOUR_LINUX: return "linux";
  92     case TUN_FLAVOUR_STREAMS: return "STREAMS";
  93     default: return "unknown";
  94     }
  95 }
  96
  97 static int tun_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  98                           int *timeout_io, const struct timeval *tv_now,
  99                           uint64_t *now)
 100 {
 101     struct tun *st=sst;
 102     *nfds_io=1;
 103     fds[0].fd=st->fd;
 104     fds[0].events=POLLIN;
 105     return 0;
 106 }
 107
 108 static void tun_afterpoll(void *sst, struct pollfd *fds, int nfds,
 109                           const struct timeval *tv_now, uint64_t *now)
 110 {
 111     struct tun *st=sst;
 112     int l;
 113
 114     if (nfds==0) return;
 115     if (fds[0].revents&POLLERR) {
 116         printf("tun_afterpoll: hup!\n");
 117     }
 118     if (fds[0].revents&POLLIN) {
 119         BUF_ALLOC(st->buff,"tun_afterpoll");
 120         buffer_init(st->buff,st->nl.max_start_pad);
 121         l=read(st->fd,st->buff->start,st->buff->len-st->nl.max_start_pad);
 122         if (l<0) {
 123             fatal_perror("tun_afterpoll: read()");
 124         }
 125         if (l==0) {
 126             fatal("tun_afterpoll: read()=0; device gone away?");
 127         }
 128         if (l>0) {
 129             st->buff->size=l;
 130             st->netlink_to_tunnel(&st->nl,st->buff);
 131             BUF_ASSERT_FREE(st->buff);
 132         }
 133     }
 134 }
 135
 136 static void tun_deliver_to_kernel(void *sst, struct buffer_if *buf)
 137 {
 138     struct tun *st=sst;
 139
 140     BUF_ASSERT_USED(buf);
 141     /* No error checking, because we'd just throw the packet away
 142        anyway if it didn't work. */
 143     write(st->fd,buf->start,buf->size);
 144     BUF_FREE(buf);
 145 }
 146
 147 static bool_t tun_set_route(void *sst, struct netlink_client *routes)
 148 {
 149     struct tun *st=sst;
 150     string_t network, mask, secnetaddr;
 151     struct subnet_list *nets;
 152     uint32_t i;
 153     int fd=-1;
 154
 155     if (routes->up == routes->kup) return False;
 156     if (st->route_type==TUN_CONFIG_IOCTL) {
 157         if (st->tun_flavour==TUN_FLAVOUR_STREAMS) {
 158             fd=open(st->ip_path,O_RDWR);
 159             if (fd<0) {
 160                 fatal_perror("tun_set_route: can't open %s",st->ip_path);
 161             }
 162         } else {
 163             fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
 164             if (fd<0) {
 165                 fatal_perror("tun_set_route: socket()");
 166             }
 167         }
 168     }
 169     nets=routes->subnets;
 170     secnetaddr=ipaddr_to_string(st->nl.secnet_address);
 171     for (i=0; i<nets->entries; i++) {
 172         network=ipaddr_to_string(nets->list[i].prefix);
 173         mask=ipaddr_to_string(nets->list[i].mask);
 174         Message(M_INFO,"%s: %s route %s/%d %s kernel routing table\n",
 175                 st->nl.name,routes->up?"adding":"deleting",network,
 176                 nets->list[i].len,routes->up?"to":"from");
 177         switch (st->route_type) {
 178         case TUN_CONFIG_LINUX:
 179             sys_cmd(st->route_path,"route",routes->up?"add":"del",
 180                     "-net",network,"netmask",mask,
 181                     "gw",secnetaddr,(char *)0);
 182             break;
 183         case TUN_CONFIG_BSD:
 184             sys_cmd(st->route_path,"route",routes->up?"add":"del",
 185                     "-net",network,secnetaddr,mask,(char *)0);
 186             break;
 187         case TUN_CONFIG_SOLARIS25:
 188             sys_cmd(st->route_path,"route",routes->up?"add":"del",
 189                     network,secnetaddr,(char *)0);
 190             break;
 191         case TUN_CONFIG_IOCTL:
 192         {
 193 #ifdef HAVE_NET_ROUTE_H
 194             struct rtentry rt;
 195             struct sockaddr_in *sa;
 196             int action;
 197
 198             memset(&rt,0,sizeof(rt));
 199             sa=(struct sockaddr_in *)&rt.rt_dst;
 200             sa->sin_family=AF_INET;
 201             sa->sin_addr.s_addr=htonl(nets->list[i].prefix);
 202             sa=(struct sockaddr_in *)&rt.rt_genmask;
 203             sa->sin_family=AF_INET;
 204             sa->sin_addr.s_addr=htonl(nets->list[i].mask);
 205             sa=(struct sockaddr_in *)&rt.rt_gateway;
 206             sa->sin_family=AF_INET;
 207             sa->sin_addr.s_addr=htonl(st->nl.secnet_address);
 208             rt.rt_flags=RTF_UP|RTF_GATEWAY;
 209             action=routes->up?SIOCADDRT:SIOCDELRT;
 210             if (ioctl(fd,action,&rt)<0) {
 211                 fatal_perror("tun_set_route: ioctl()");
 212             }
 213 #else
 214             fatal("tun_set_route: ioctl method not supported");
 215 #endif
 216         }
 217         break;
 218         default:
 219             fatal("tun_set_route: unsupported route command type");
 220             break;
 221         }
 222         free(network); free(mask);
 223     }
 224     free(secnetaddr);
 225     if (st->route_type==TUN_CONFIG_IOCTL) {
 226         close(fd);
 227     }
 228     routes->kup=routes->up;
 229     return True;
 230 }
 231
 232 static void tun_phase_hook(void *sst, uint32_t newphase)
 233 {
 234     struct tun *st=sst;
 235     string_t hostaddr,secnetaddr;
 236     uint8_t mtu[6];
 237     struct netlink_client *r;
 238
 239     if (st->tun_flavour==TUN_FLAVOUR_BSD) {
 240         if (st->search_for_if) {
 241             string_t dname;
 242             int i;
 243
 244             dname=safe_malloc(strlen(st->device_path)+4,"tun_old_apply");
 245             st->interface_name=safe_malloc(8,"tun_phase_hook");
 246
 247             for (i=0; i<255; i++) {
 248                 sprintf(dname,"%s%d",st->device_path,i);
 249                 if ((st->fd=open(dname,O_RDWR))>0) {
 250                     sprintf(st->interface_name,"tun%d",i);
 251                     Message(M_INFO,"%s: allocated network interface %s "
 252                             "through %s\n",st->nl.name,st->interface_name,
 253                             dname);
 254                     break;
 255                 }
 256             }
 257             if (st->fd==-1) {
 258                 fatal("%s: unable to open any TUN device (%s...)",
 259                       st->nl.name,st->device_path);
 260             }
 261         } else {
 262             st->fd=open(st->device_path,O_RDWR);
 263             if (st->fd==-1) {
 264                 fatal_perror("%s: unable to open TUN device file %s",
 265                              st->nl.name,st->device_path);
 266             }
 267         }
 268     } else if (st->tun_flavour==TUN_FLAVOUR_LINUX) {
 269 #ifdef LINUX_TUN_SUPPORTED
 270         struct ifreq ifr;
 271
 272         /* New TUN interface: open the device, then do ioctl TUNSETIFF
 273            to set or find out the network interface name. */
 274         st->fd=open(st->device_path,O_RDWR);
 275         if (st->fd==-1) {
 276             fatal_perror("%s: can't open device file %s",st->nl.name,
 277                          st->device_path);
 278         }
 279         memset(&ifr,0,sizeof(ifr));
 280         ifr.ifr_flags = IFF_TUN | IFF_NO_PI; /* Just send/receive IP packets,
 281                                                 no extra headers */
 282         if (st->interface_name)
 283             strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 284         if (ioctl(st->fd,TUNSETIFF,&ifr)<0) {
 285             fatal_perror("%s: ioctl(TUNSETIFF)",st->nl.name);
 286         }
 287         if (!st->interface_name) {
 288             st->interface_name=safe_malloc(strlen(ifr.ifr_name)+1,"tun_apply");
 289             strcpy(st->interface_name,ifr.ifr_name);
 290             Message(M_INFO,"%s: allocated network interface %s\n",st->nl.name,
 291                     st->interface_name);
 292         }
 293 #else
 294         fatal("tun_phase_hook: TUN_FLAVOUR_LINUX unexpected");
 295 #endif /* LINUX_TUN_SUPPORTED */
 296     } else if (st->tun_flavour==TUN_FLAVOUR_STREAMS) {
 297 #ifdef HAVE_TUN_STREAMS
 298         int tun_fd, if_fd, ppa=-1, ip_fd;
 299
 300         if ((ip_fd=open(st->ip_path, O_RDWR)) < 0) {
 301             fatal_perror("%s: can't open %s",st->nl.name,st->ip_path);
 302         }
 303         if ((tun_fd=open(st->device_path,O_RDWR)) < 0) {
 304             fatal_perror("%s: can't open %s",st->nl.name,st->device_path);
 305         }
 306         if ((ppa=ioctl(tun_fd,TUNNEWPPA,ppa)) < 0) {
 307             fatal_perror("%s: can't assign new interface");
 308         }
 309         if ((if_fd=open(st->device_path,O_RDWR)) < 0) {
 310             fatal_perror("%s: can't open %s (2)",st->nl.name,st->device_path);
 311         }
 312         if (ioctl(if_fd,I_PUSH,"ip") < 0) {
 313             fatal_perror("%s: can't push IP module",st->nl.name);
 314         }
 315         if (ioctl(if_fd,IF_UNITSEL,(char *)&ppa) < 0) {
 316             fatal_perror("%s: can't set ppa %d",st->nl.name,ppa);
 317         }
 318         if (ioctl(ip_fd, I_LINK, if_fd) < 0) {
 319             fatal_perror("%s: can't link TUN device to IP",st->nl.name);
 320         }
 321         st->interface_name=safe_malloc(10,"tun_apply");
 322         sprintf(st->interface_name,"tun%d",ppa);
 323         st->fd=tun_fd;
 324 #else
 325         fatal("tun_phase_hook: TUN_FLAVOUR_STREAMS unexpected");
 326 #endif /* HAVE_TUN_STREAMS */
 327     } else {
 328         fatal("tun_phase_hook: unknown flavour of TUN");
 329     }
 330     /* All the networks we'll be using have been registered. Invoke ifconfig
 331        to set the TUN device's address, and route to add routes to all
 332        our networks. */
 333
 334     hostaddr=ipaddr_to_string(st->local_address);
 335     secnetaddr=ipaddr_to_string(st->nl.secnet_address);
 336     snprintf(mtu,6,"%d",st->nl.mtu);
 337     mtu[5]=0;
 338
 339     switch (st->ifconfig_type) {
 340     case TUN_CONFIG_LINUX:
 341         sys_cmd(st->ifconfig_path,"ifconfig",st->interface_name,
 342                 hostaddr,"netmask","255.255.255.255","-broadcast",
 343                 "-multicast",
 344                 "pointopoint",secnetaddr,"mtu",mtu,"up",(char *)0);
 345         break;
 346     case TUN_CONFIG_BSD:
 347         sys_cmd(st->ifconfig_path,"ifconfig",st->interface_name,
 348                 hostaddr,"netmask","255.255.255.255",
 349                 secnetaddr,"mtu",mtu,"up",(char *)0);
 350         break;
 351     case TUN_CONFIG_SOLARIS25:
 352         sys_cmd(st->ifconfig_path,"ifconfig",st->interface_name,
 353                 hostaddr,secnetaddr,"mtu",mtu,"up",(char *)0);
 354         break;
 355     case TUN_CONFIG_IOCTL:
 356 #ifdef HAVE_NET_IF_H
 357     {
 358         int fd;
 359         struct ifreq ifr;
 360         struct sockaddr_in *sa;
 361         fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
 362
 363         /* Interface address */
 364         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 365         sa=(struct sockaddr_in *)&ifr.ifr_addr;
 366         memset(sa,0,sizeof(*sa));
 367         sa->sin_family=AF_INET;
 368         sa->sin_addr.s_addr=htonl(st->local_address);
 369         if (ioctl(fd,SIOCSIFADDR, &ifr)!=0) {
 370             fatal_perror("tun_apply: SIOCSIFADDR");
 371         }
 372 #ifdef SIOCSIFNETMASK
 373         /* Netmask */
 374         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 375         sa=(struct sockaddr_in *)&ifr.ifr_netmask;
 376         memset(sa,0,sizeof(*sa));
 377         sa->sin_family=AF_INET;
 378         sa->sin_addr.s_addr=htonl(0xffffffff);
 379         if (ioctl(fd,SIOCSIFNETMASK, &ifr)!=0) {
 380             fatal_perror("tun_apply: SIOCSIFNETMASK");
 381         }
 382 #endif
 383         /* Destination address (point-to-point) */
 384         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 385         sa=(struct sockaddr_in *)&ifr.ifr_dstaddr;
 386         memset(sa,0,sizeof(*sa));
 387         sa->sin_family=AF_INET;
 388         sa->sin_addr.s_addr=htonl(st->nl.secnet_address);
 389         if (ioctl(fd,SIOCSIFDSTADDR, &ifr)!=0) {
 390             fatal_perror("tun_apply: SIOCSIFDSTADDR");
 391         }
 392         /* MTU */
 393         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 394         ifr.ifr_mtu=st->nl.mtu;
 395         if (ioctl(fd,SIOCSIFMTU, &ifr)!=0) {
 396             fatal_perror("tun_apply: SIOCSIFMTU");
 397         }
 398         /* Flags */
 399         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 400         ifr.ifr_flags=IFF_UP|IFF_POINTOPOINT|IFF_RUNNING|IFF_NOARP;
 401         if (ioctl(fd,SIOCSIFFLAGS, &ifr)!=0) {
 402             fatal_perror("tun_apply: SIOCSIFFLAGS");
 403         }
 404
 405         close(fd);
 406     }
 407 #else
 408     fatal("tun_apply: ifconfig by ioctl() not supported");
 409 #endif /* HAVE_NET_IF_H */
 410     break;
 411     default:
 412         fatal("tun_apply: unsupported ifconfig method");
 413         break;
 414     }
 415
 416     for (r=st->nl.clients; r; r=r->next) {
 417         tun_set_route(st,r);
 418     }
 419
 420     /* Register for poll() */
 421     register_for_poll(st, tun_beforepoll, tun_afterpoll, 1, st->nl.name);
 422 }
 423
 424 static list_t *tun_create(closure_t *self, struct cloc loc, dict_t *context,
 425                           list_t *args,uint32_t default_flavour)
 426 {
 427     struct tun *st;
 428     item_t *item;
 429     dict_t *dict;
 430     string_t flavour,type;
 431
 432     st=safe_malloc(sizeof(*st),"tun_apply");
 433
 434     /* First parameter must be a dict */
 435     item=list_elem(args,0);
 436     if (!item || item->type!=t_dict)
 437         cfgfatal(loc,"tun","parameter must be a dictionary\n");
 438
 439     dict=item->data.dict;
 440
 441     st->netlink_to_tunnel=
 442         netlink_init(&st->nl,st,loc,dict,
 443                      "netlink-tun",tun_set_route,tun_deliver_to_kernel);
 444
 445     flavour=dict_read_string(dict,"flavour",False,"tun-netlink",loc);
 446     if (flavour)
 447         st->tun_flavour=string_to_word(flavour,loc,flavours,"tun-flavour");
 448     else
 449         st->tun_flavour=default_flavour;
 450
 451     st->device_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
 452     st->ip_path=dict_read_string(dict,"ip-path",False,"tun-netlink",loc);
 453     st->interface_name=dict_read_string(dict,"interface",False,
 454                                         "tun-netlink",loc);
 455     st->search_for_if=dict_read_bool(dict,"interface-search",False,
 456                                      "tun-netlink",loc,st->device_path==NULL);
 457
 458     type=dict_read_string(dict,"ifconfig-type",False,"tun-netlink",loc);
 459     if (type) st->ifconfig_type=string_to_word(type,loc,config_types,
 460                                                "ifconfig-type");
 461     else st->ifconfig_type=TUN_CONFIG_GUESS;
 462     st->ifconfig_path=dict_read_string(dict,"ifconfig-path",False,
 463                                        "tun-netlink",loc);
 464
 465     type=dict_read_string(dict,"route-type",False,"tun-netlink",loc);
 466     if (type) st->route_type=string_to_word(type,loc,config_types,
 467                                             "route-type");
 468     else st->route_type=TUN_CONFIG_GUESS;
 469     st->route_path=dict_read_string(dict,"route-path",False,"tun-netlink",loc);
 470
 471     st->buff=find_cl_if(dict,"buffer",CL_BUFFER,True,"tun-netlink",loc);
 472     st->local_address=string_item_to_ipaddr(
 473         dict_find_item(dict,"local-address", True, "netlink", loc),"netlink");
 474
 475     if (st->tun_flavour==TUN_FLAVOUR_GUESS) {
 476         /* If we haven't been told what type of TUN we're using, take
 477            a guess based on the system details. */
 478         struct utsname u;
 479         if (uname(&u)<0) {
 480             fatal_perror("tun_create: uname");
 481         }
 482         if (strcmp(u.sysname,"Linux")==0) {
 483             if (u.release[0]=='2' && u.release[1]=='.' && u.release[3]=='.') {
 484                 if (u.release[2]=='2') st->tun_flavour=TUN_FLAVOUR_BSD;
 485                 else if (u.release[2]=='4') st->tun_flavour=TUN_FLAVOUR_LINUX;
 486             }
 487         } else if (strcmp(u.sysname,"SunOS")==0) {
 488             st->tun_flavour=TUN_FLAVOUR_STREAMS;
 489         } else if (strcmp(u.sysname,"FreeBSD")==0) {
 490             st->tun_flavour=TUN_FLAVOUR_BSD;
 491         }
 492     }
 493     if (st->tun_flavour==TUN_FLAVOUR_GUESS) {
 494         cfgfatal(loc,"tun","cannot guess which type of TUN is in use; "
 495                  "specify the flavour explicitly\n");
 496     }
 497
 498     if (st->ifconfig_type==TUN_CONFIG_GUESS) {
 499         switch (st->tun_flavour) {
 500         case TUN_FLAVOUR_LINUX:
 501             st->ifconfig_type=TUN_CONFIG_IOCTL;
 502             break;
 503         case TUN_FLAVOUR_BSD:
 504             /* XXX on Linux we still want TUN_CONFIG_IOCTL.  Perhaps we can
 505                use this on BSD too. */
 506             st->ifconfig_type=TUN_CONFIG_IOCTL;
 507             break;
 508         case TUN_FLAVOUR_STREAMS:
 509             st->ifconfig_type=TUN_CONFIG_BSD;
 510             break;
 511         }
 512     }
 513     if (st->route_type==TUN_CONFIG_GUESS)
 514         st->route_type=st->ifconfig_type;
 515
 516     if (st->ifconfig_type==TUN_CONFIG_GUESS) {
 517         cfgfatal(loc,"tun","cannot guess which ifconfig method to use\n");
 518     }
 519     if (st->route_type==TUN_CONFIG_GUESS) {
 520         cfgfatal(loc,"tun","cannot guess which route method to use\n");
 521     }
 522
 523     if (st->ifconfig_type==TUN_CONFIG_IOCTL && st->ifconfig_path) {
 524         cfgfatal(loc,"tun","ifconfig-type \"ioctl\" is incompatible with "
 525                  "ifconfig-path\n");
 526     }
 527     if (st->route_type==TUN_CONFIG_IOCTL && st->route_path) {
 528         cfgfatal(loc,"tun","route-type \"ioctl\" is incompatible with "
 529                  "route-path\n");
 530     }
 531
 532     Message(M_DEBUG_CONFIG,"%s: tun flavour %s\n",st->nl.name,
 533             tun_flavour_str(st->tun_flavour));
 534     switch (st->tun_flavour) {
 535     case TUN_FLAVOUR_BSD:
 536         if (!st->device_path) st->device_path="/dev/tun";
 537         break;
 538     case TUN_FLAVOUR_LINUX:
 539         if (!st->device_path) st->device_path="/dev/net/tun";
 540         break;
 541     case TUN_FLAVOUR_STREAMS:
 542         if (!st->device_path) st->device_path="/dev/tun";
 543         if (st->interface_name) cfgfatal(loc,"tun","interface name cannot "
 544                                          "be specified with STREAMS TUN\n");
 545         break;
 546     }
 547
 548     if (!st->ip_path) st->ip_path="/dev/ip";
 549     if (!st->ifconfig_path) st->ifconfig_path="ifconfig";
 550     if (!st->route_path) st->route_path="route";
 551
 552 #ifndef HAVE_TUN_STREAMS
 553     if (st->tun_flavour==TUN_FLAVOUR_STREAMS) {
 554         cfgfatal(loc,"tun","TUN flavour STREAMS unsupported in this build "
 555                  "of secnet\n");
 556     }
 557 #endif
 558 #ifndef LINUX_TUN_SUPPORTED
 559     if (st->tun_flavour==TUN_FLAVOUR_LINUX) {
 560         cfgfatal(loc,"tun","TUN flavour LINUX unsupported in this build "
 561                  "of secnet\n");
 562     }
 563 #endif
 564
 565     /* Old TUN interface: the network interface name depends on which
 566        /dev/tunX file we open. If 'interface-search' is set to true, treat
 567        'device' as the prefix and try numbers from 0--255. If it's set
 568        to false, treat 'device' as the whole name, and require than an
 569        appropriate interface name be specified. */
 570     if (st->tun_flavour==TUN_FLAVOUR_BSD) {
 571         if (st->search_for_if && st->interface_name) {
 572             cfgfatal(loc,"tun","you may not specify an interface name "
 573                      "in interface-search mode\n");
 574         }
 575         if (!st->search_for_if && !st->interface_name) {
 576             cfgfatal(loc,"tun","you must specify an interface name "
 577                      "when you explicitly specify a TUN device file\n");
 578         }
 579     }
 580
 581     add_hook(PHASE_GETRESOURCES,tun_phase_hook,st);
 582
 583     return new_closure(&st->nl.cl);
 584 }
 585
 586 static list_t *tun_apply(closure_t *self, struct cloc loc, dict_t *context,
 587                          list_t *args)
 588 {
 589     return tun_create(self,loc,context,args,TUN_FLAVOUR_GUESS);
 590 }
 591
 592 static list_t *tun_bsd_apply(closure_t *self, struct cloc loc, dict_t *context,
 593                              list_t *args)
 594 {
 595     Message(M_WARNING,"(%s,%d): obsolete use of tun-old; replace with tun "
 596             "and specify flavour \"bsd\".\n",loc.file,loc.line);
 597     return tun_create(self,loc,context,args,TUN_FLAVOUR_BSD);
 598 }
 599
 600 init_module tun_module;
 601 void tun_module(dict_t *dict)
 602 {
 603     add_closure(dict,"tun",tun_apply);
 604     add_closure(dict,"tun-old",tun_bsd_apply);
 605 }