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 <errno.h>
   7 #include <unistd.h>
   8 #include <fcntl.h>
   9 #include <sys/ioctl.h>
  10 #include <sys/utsname.h>
  11 #include <sys/socket.h>
  12
  13 #ifdef HAVE_NET_IF_H
  14 #include <net/if.h>
  15 #ifdef HAVE_LINUX_IF_H
  16 #include <linux/if_tun.h>
  17 #define LINUX_TUN_SUPPORTED
  18 #endif
  19 #endif
  20
  21 #ifdef HAVE_NET_ROUTE_H
  22 #include <net/route.h>
  23 #endif
  24
  25 #if defined(HAVE_STROPTS_H) && defined(HAVE_SYS_SOCKIO_H) && \
  26 defined(HAVE_NET_IF_TUN_H)
  27 #define HAVE_TUN_STREAMS
  28 #endif
  29
  30 #ifdef HAVE_TUN_STREAMS
  31 #include <stropts.h>
  32 #include <sys/sockio.h>
  33 #include <net/if_tun.h>
  34 #endif
  35
  36 #define TUN_FLAVOUR_GUESS   0
  37 #define TUN_FLAVOUR_BSD     1
  38 #define TUN_FLAVOUR_LINUX   2
  39 #define TUN_FLAVOUR_STREAMS 3
  40
  41 static struct flagstr flavours[]={
  42     {"guess", TUN_FLAVOUR_GUESS},
  43     {"bsd", TUN_FLAVOUR_BSD},
  44     {"BSD", TUN_FLAVOUR_BSD},
  45     {"linux", TUN_FLAVOUR_LINUX},
  46     {"streams", TUN_FLAVOUR_STREAMS},
  47     {"STREAMS", TUN_FLAVOUR_STREAMS},
  48     {NULL, 0}
  49 };
  50
  51 #define TUN_CONFIG_GUESS      0
  52 #define TUN_CONFIG_IOCTL      1
  53 #define TUN_CONFIG_BSD        2
  54 #define TUN_CONFIG_LINUX      3
  55 #define TUN_CONFIG_SOLARIS25  4
  56
  57 static struct flagstr config_types[]={
  58     {"guess", TUN_CONFIG_GUESS},
  59     {"ioctl", TUN_CONFIG_IOCTL},
  60     {"bsd", TUN_CONFIG_BSD},
  61     {"BSD", TUN_CONFIG_BSD},
  62     {"linux", TUN_CONFIG_LINUX},
  63     {"solaris-2.5", TUN_CONFIG_SOLARIS25},
  64     {NULL, 0}
  65 };
  66
  67 /* Connection to the kernel through the universal TUN/TAP driver */
  68
  69 struct tun {
  70     struct netlink nl;
  71     int fd;
  72     cstring_t device_path;
  73     cstring_t ip_path;
  74     string_t interface_name;
  75     cstring_t ifconfig_path;
  76     uint32_t ifconfig_type;
  77     cstring_t route_path;
  78     uint32_t route_type;
  79     uint32_t tun_flavour;
  80     bool_t search_for_if; /* Applies to tun-BSD only */
  81     struct buffer_if *buff; /* We receive packets into here
  82                                and send them to the netlink code. */
  83     netlink_deliver_fn *netlink_to_tunnel;
  84     uint32_t local_address; /* host interface address */
  85 };
  86
  87 static cstring_t tun_flavour_str(uint32_t flavour)
  88 {
  89     switch (flavour) {
  90     case TUN_FLAVOUR_GUESS: return "guess";
  91     case TUN_FLAVOUR_BSD: return "BSD";
  92     case TUN_FLAVOUR_LINUX: return "linux";
  93     case TUN_FLAVOUR_STREAMS: return "STREAMS";
  94     default: return "unknown";
  95     }
  96 }
  97
  98 static int tun_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  99                           int *timeout_io)
 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 {
 110     struct tun *st=sst;
 111     int l;
 112
 113     if (nfds==0) return;
 114     if (fds[0].revents&POLLERR) {
 115         printf("tun_afterpoll: hup!\n");
 116     }
 117     if (fds[0].revents&POLLIN) {
 118         BUF_ALLOC(st->buff,"tun_afterpoll");
 119         buffer_init(st->buff,st->nl.max_start_pad);
 120         l=read(st->fd,st->buff->start,st->buff->len-st->nl.max_start_pad);
 121         if (l<0) {
 122             fatal_perror("tun_afterpoll: read()");
 123         }
 124         if (l==0) {
 125             fatal("tun_afterpoll: read()=0; device gone away?");
 126         }
 127         if (l>0) {
 128             st->buff->size=l;
 129             st->netlink_to_tunnel(&st->nl,st->buff);
 130             BUF_ASSERT_FREE(st->buff);
 131         }
 132     }
 133 }
 134
 135 static void tun_deliver_to_kernel(void *sst, struct buffer_if *buf)
 136 {
 137     struct tun *st=sst;
 138     ssize_t rc;
 139
 140     BUF_ASSERT_USED(buf);
 141
 142     /* Log errors, so we can tell what's going on, but only once a
 143        minute, so we don't flood the logs.  Short writes count as
 144        errors. */
 145     rc = write(st->fd,buf->start,buf->size);
 146     if(rc != buf->size) {
 147         static struct timeval last_report;
 148         if(tv_now_global.tv_sec >= last_report.tv_sec + 60) {
 149             if(rc < 0)
 150                 Message(M_WARNING,
 151                         "failed to deliver packet to tun device: %s\n",
 152                         strerror(errno));
 153             else
 154                 Message(M_WARNING,
 155                         "truncated packet delivered to tun device\n");
 156             last_report = tv_now_global;
 157         }
 158     }
 159     BUF_FREE(buf);
 160 }
 161
 162 static bool_t tun_set_route(void *sst, struct netlink_client *routes)
 163 {
 164     struct tun *st=sst;
 165     string_t network, mask, secnetaddr;
 166     struct subnet_list *nets;
 167     int32_t i;
 168     int fd=-1;
 169
 170     if (routes->up == routes->kup) return False;
 171     if (st->route_type==TUN_CONFIG_IOCTL) {
 172         if (st->tun_flavour==TUN_FLAVOUR_STREAMS) {
 173             fd=open(st->ip_path,O_RDWR);
 174             if (fd<0) {
 175                 fatal_perror("tun_set_route: can't open %s",st->ip_path);
 176             }
 177         } else {
 178             fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
 179             if (fd<0) {
 180                 fatal_perror("tun_set_route: socket()");
 181             }
 182         }
 183     }
 184     nets=routes->subnets;
 185     secnetaddr=ipaddr_to_string(st->nl.secnet_address);
 186     for (i=0; i<nets->entries; i++) {
 187         network=ipaddr_to_string(nets->list[i].prefix);
 188         mask=ipaddr_to_string(nets->list[i].mask);
 189         Message(M_INFO,"%s: %s route %s/%d %s kernel routing table\n",
 190                 st->nl.name,routes->up?"adding":"deleting",network,
 191                 nets->list[i].len,routes->up?"to":"from");
 192         switch (st->route_type) {
 193         case TUN_CONFIG_LINUX:
 194             sys_cmd(st->route_path,"route",routes->up?"add":"del",
 195                     "-net",network,"netmask",mask,
 196                     "gw",secnetaddr,(char *)0);
 197             break;
 198         case TUN_CONFIG_BSD:
 199             sys_cmd(st->route_path,"route",routes->up?"add":"del",
 200                     "-net",network,secnetaddr,mask,(char *)0);
 201             break;
 202         case TUN_CONFIG_SOLARIS25:
 203             sys_cmd(st->route_path,"route",routes->up?"add":"del",
 204                     network,secnetaddr,(char *)0);
 205             break;
 206         case TUN_CONFIG_IOCTL:
 207         {
 208           /* darwin rtentry has a different format, use /sbin/route instead */
 209 #if HAVE_NET_ROUTE_H && ! __APPLE__
 210             struct rtentry rt;
 211             struct sockaddr_in *sa;
 212             int action;
 213
 214             memset(&rt,0,sizeof(rt));
 215             sa=(struct sockaddr_in *)&rt.rt_dst;
 216             sa->sin_family=AF_INET;
 217             sa->sin_addr.s_addr=htonl(nets->list[i].prefix);
 218             sa=(struct sockaddr_in *)&rt.rt_genmask;
 219             sa->sin_family=AF_INET;
 220             sa->sin_addr.s_addr=htonl(nets->list[i].mask);
 221             sa=(struct sockaddr_in *)&rt.rt_gateway;
 222             sa->sin_family=AF_INET;
 223             sa->sin_addr.s_addr=htonl(st->nl.secnet_address);
 224             rt.rt_flags=RTF_UP|RTF_GATEWAY;
 225             action=routes->up?SIOCADDRT:SIOCDELRT;
 226             if (ioctl(fd,action,&rt)<0) {
 227                 fatal_perror("tun_set_route: ioctl()");
 228             }
 229 #else
 230             fatal("tun_set_route: ioctl method not supported");
 231 #endif
 232         }
 233         break;
 234         default:
 235             fatal("tun_set_route: unsupported route command type");
 236             break;
 237         }
 238         free(network); free(mask);
 239     }
 240     free(secnetaddr);
 241     if (st->route_type==TUN_CONFIG_IOCTL) {
 242         close(fd);
 243     }
 244     routes->kup=routes->up;
 245     return True;
 246 }
 247
 248 static void tun_phase_hook(void *sst, uint32_t newphase)
 249 {
 250     struct tun *st=sst;
 251     string_t hostaddr,secnetaddr;
 252     char mtu[6];
 253     struct netlink_client *r;
 254
 255     if (st->tun_flavour==TUN_FLAVOUR_BSD) {
 256         if (st->search_for_if) {
 257             string_t dname;
 258             int i;
 259
 260             dname=safe_malloc(strlen(st->device_path)+4,"tun_old_apply");
 261             st->interface_name=safe_malloc(8,"tun_phase_hook");
 262
 263             for (i=0; i<255; i++) {
 264                 sprintf(dname,"%s%d",st->device_path,i);
 265                 if ((st->fd=open(dname,O_RDWR))>0) {
 266                     sprintf(st->interface_name,"tun%d",i);
 267                     Message(M_INFO,"%s: allocated network interface %s "
 268                             "through %s\n",st->nl.name,st->interface_name,
 269                             dname);
 270                     break;
 271                 }
 272             }
 273             if (st->fd==-1) {
 274                 fatal("%s: unable to open any TUN device (%s...)",
 275                       st->nl.name,st->device_path);
 276             }
 277         } else {
 278             st->fd=open(st->device_path,O_RDWR);
 279             if (st->fd==-1) {
 280                 fatal_perror("%s: unable to open TUN device file %s",
 281                              st->nl.name,st->device_path);
 282             }
 283         }
 284     } else if (st->tun_flavour==TUN_FLAVOUR_LINUX) {
 285 #ifdef LINUX_TUN_SUPPORTED
 286         struct ifreq ifr;
 287
 288         /* New TUN interface: open the device, then do ioctl TUNSETIFF
 289            to set or find out the network interface name. */
 290         st->fd=open(st->device_path,O_RDWR);
 291         if (st->fd==-1) {
 292             fatal_perror("%s: can't open device file %s",st->nl.name,
 293                          st->device_path);
 294         }
 295         memset(&ifr,0,sizeof(ifr));
 296         ifr.ifr_flags = IFF_TUN | IFF_NO_PI; /* Just send/receive IP packets,
 297                                                 no extra headers */
 298         if (st->interface_name)
 299             strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 300         if (ioctl(st->fd,TUNSETIFF,&ifr)<0) {
 301             fatal_perror("%s: ioctl(TUNSETIFF)",st->nl.name);
 302         }
 303         if (!st->interface_name) {
 304             st->interface_name=safe_malloc(strlen(ifr.ifr_name)+1,"tun_apply");
 305             strcpy(st->interface_name,ifr.ifr_name);
 306             Message(M_INFO,"%s: allocated network interface %s\n",st->nl.name,
 307                     st->interface_name);
 308         }
 309 #else
 310         fatal("tun_phase_hook: TUN_FLAVOUR_LINUX unexpected");
 311 #endif /* LINUX_TUN_SUPPORTED */
 312     } else if (st->tun_flavour==TUN_FLAVOUR_STREAMS) {
 313 #ifdef HAVE_TUN_STREAMS
 314         int tun_fd, if_fd, ppa=-1, ip_fd;
 315
 316         if ((ip_fd=open(st->ip_path, O_RDWR)) < 0) {
 317             fatal_perror("%s: can't open %s",st->nl.name,st->ip_path);
 318         }
 319         if ((tun_fd=open(st->device_path,O_RDWR)) < 0) {
 320             fatal_perror("%s: can't open %s",st->nl.name,st->device_path);
 321         }
 322         if ((ppa=ioctl(tun_fd,TUNNEWPPA,ppa)) < 0) {
 323             fatal_perror("%s: can't assign new interface");
 324         }
 325         if ((if_fd=open(st->device_path,O_RDWR)) < 0) {
 326             fatal_perror("%s: can't open %s (2)",st->nl.name,st->device_path);
 327         }
 328         if (ioctl(if_fd,I_PUSH,"ip") < 0) {
 329             fatal_perror("%s: can't push IP module",st->nl.name);
 330         }
 331         if (ioctl(if_fd,IF_UNITSEL,(char *)&ppa) < 0) {
 332             fatal_perror("%s: can't set ppa %d",st->nl.name,ppa);
 333         }
 334         if (ioctl(ip_fd, I_LINK, if_fd) < 0) {
 335             fatal_perror("%s: can't link TUN device to IP",st->nl.name);
 336         }
 337         st->interface_name=safe_malloc(10,"tun_apply");
 338         sprintf(st->interface_name,"tun%d",ppa);
 339         st->fd=tun_fd;
 340 #else
 341         fatal("tun_phase_hook: TUN_FLAVOUR_STREAMS unexpected");
 342 #endif /* HAVE_TUN_STREAMS */
 343     } else {
 344         fatal("tun_phase_hook: unknown flavour of TUN");
 345     }
 346     /* All the networks we'll be using have been registered. Invoke ifconfig
 347        to set the TUN device's address, and route to add routes to all
 348        our networks. */
 349
 350     hostaddr=ipaddr_to_string(st->local_address);
 351     secnetaddr=ipaddr_to_string(st->nl.secnet_address);
 352     snprintf(mtu,sizeof(mtu),"%d",st->nl.mtu);
 353     mtu[5]=0;
 354
 355     switch (st->ifconfig_type) {
 356     case TUN_CONFIG_LINUX:
 357         sys_cmd(st->ifconfig_path,"ifconfig",st->interface_name,
 358                 hostaddr,"netmask","255.255.255.255","-broadcast",
 359                 "-multicast",
 360                 "pointopoint",secnetaddr,"mtu",mtu,"up",(char *)0);
 361         break;
 362     case TUN_CONFIG_BSD:
 363         sys_cmd(st->ifconfig_path,"ifconfig",st->interface_name,
 364                 hostaddr,"netmask","255.255.255.255",
 365                 secnetaddr,"mtu",mtu,"up",(char *)0);
 366         break;
 367     case TUN_CONFIG_SOLARIS25:
 368         sys_cmd(st->ifconfig_path,"ifconfig",st->interface_name,
 369                 hostaddr,secnetaddr,"mtu",mtu,"up",(char *)0);
 370         break;
 371     case TUN_CONFIG_IOCTL:
 372 #if HAVE_NET_IF_H && ! __APPLE__
 373     {
 374         int fd;
 375         struct ifreq ifr;
 376         struct sockaddr_in *sa;
 377         fd=socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
 378
 379         /* Interface address */
 380         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 381         sa=(struct sockaddr_in *)&ifr.ifr_addr;
 382         memset(sa,0,sizeof(*sa));
 383         sa->sin_family=AF_INET;
 384         sa->sin_addr.s_addr=htonl(st->local_address);
 385         if (ioctl(fd,SIOCSIFADDR, &ifr)!=0) {
 386             fatal_perror("tun_apply: SIOCSIFADDR");
 387         }
 388 #ifdef SIOCSIFNETMASK
 389         /* Netmask */
 390         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 391         sa=(struct sockaddr_in *)&ifr.ifr_netmask;
 392         memset(sa,0,sizeof(*sa));
 393         sa->sin_family=AF_INET;
 394         sa->sin_addr.s_addr=htonl(0xffffffff);
 395         if (ioctl(fd,SIOCSIFNETMASK, &ifr)!=0) {
 396             fatal_perror("tun_apply: SIOCSIFNETMASK");
 397         }
 398 #endif
 399         /* Destination address (point-to-point) */
 400         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 401         sa=(struct sockaddr_in *)&ifr.ifr_dstaddr;
 402         memset(sa,0,sizeof(*sa));
 403         sa->sin_family=AF_INET;
 404         sa->sin_addr.s_addr=htonl(st->nl.secnet_address);
 405         if (ioctl(fd,SIOCSIFDSTADDR, &ifr)!=0) {
 406             fatal_perror("tun_apply: SIOCSIFDSTADDR");
 407         }
 408         /* MTU */
 409         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 410         ifr.ifr_mtu=st->nl.mtu;
 411         if (ioctl(fd,SIOCSIFMTU, &ifr)!=0) {
 412             fatal_perror("tun_apply: SIOCSIFMTU");
 413         }
 414         /* Flags */
 415         strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 416         ifr.ifr_flags=IFF_UP|IFF_POINTOPOINT|IFF_RUNNING|IFF_NOARP;
 417         if (ioctl(fd,SIOCSIFFLAGS, &ifr)!=0) {
 418             fatal_perror("tun_apply: SIOCSIFFLAGS");
 419         }
 420
 421         close(fd);
 422     }
 423 #else
 424     fatal("tun_apply: ifconfig by ioctl() not supported");
 425 #endif /* HAVE_NET_IF_H */
 426     break;
 427     default:
 428         fatal("tun_apply: unsupported ifconfig method");
 429         break;
 430     }
 431
 432     for (r=st->nl.clients; r; r=r->next) {
 433         tun_set_route(st,r);
 434     }
 435
 436     /* Register for poll() */
 437     register_for_poll(st, tun_beforepoll, tun_afterpoll, 1, st->nl.name);
 438 }
 439
 440 static list_t *tun_create(closure_t *self, struct cloc loc, dict_t *context,
 441                           list_t *args,uint32_t default_flavour)
 442 {
 443     struct tun *st;
 444     item_t *item;
 445     dict_t *dict;
 446     string_t flavour,type;
 447
 448     st=safe_malloc(sizeof(*st),"tun_apply");
 449
 450     /* First parameter must be a dict */
 451     item=list_elem(args,0);
 452     if (!item || item->type!=t_dict)
 453         cfgfatal(loc,"tun","parameter must be a dictionary\n");
 454
 455     dict=item->data.dict;
 456
 457     st->netlink_to_tunnel=
 458         netlink_init(&st->nl,st,loc,dict,
 459                      "netlink-tun",tun_set_route,tun_deliver_to_kernel);
 460
 461     flavour=dict_read_string(dict,"flavour",False,"tun-netlink",loc);
 462     if (flavour)
 463         st->tun_flavour=string_to_word(flavour,loc,flavours,"tun-flavour");
 464     else
 465         st->tun_flavour=default_flavour;
 466
 467     st->device_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
 468     st->ip_path=dict_read_string(dict,"ip-path",False,"tun-netlink",loc);
 469     st->interface_name=dict_read_string(dict,"interface",False,
 470                                         "tun-netlink",loc);
 471     st->search_for_if=dict_read_bool(dict,"interface-search",False,
 472                                      "tun-netlink",loc,st->device_path==NULL);
 473
 474     type=dict_read_string(dict,"ifconfig-type",False,"tun-netlink",loc);
 475     if (type) st->ifconfig_type=string_to_word(type,loc,config_types,
 476                                                "ifconfig-type");
 477     else st->ifconfig_type=TUN_CONFIG_GUESS;
 478     st->ifconfig_path=dict_read_string(dict,"ifconfig-path",False,
 479                                        "tun-netlink",loc);
 480
 481     type=dict_read_string(dict,"route-type",False,"tun-netlink",loc);
 482     if (type) st->route_type=string_to_word(type,loc,config_types,
 483                                             "route-type");
 484     else st->route_type=TUN_CONFIG_GUESS;
 485     st->route_path=dict_read_string(dict,"route-path",False,"tun-netlink",loc);
 486
 487     st->buff=find_cl_if(dict,"buffer",CL_BUFFER,True,"tun-netlink",loc);
 488     st->local_address=string_item_to_ipaddr(
 489         dict_find_item(dict,"local-address", True, "netlink", loc),"netlink");
 490
 491     if (st->tun_flavour==TUN_FLAVOUR_GUESS) {
 492         /* If we haven't been told what type of TUN we're using, take
 493            a guess based on the system details. */
 494         struct utsname u;
 495         if (uname(&u)<0) {
 496             fatal_perror("tun_create: uname");
 497         }
 498         if (strcmp(u.sysname,"Linux")==0) {
 499             st->tun_flavour=TUN_FLAVOUR_LINUX;
 500         } else if (strcmp(u.sysname,"SunOS")==0) {
 501             st->tun_flavour=TUN_FLAVOUR_STREAMS;
 502         } else if (strcmp(u.sysname,"FreeBSD")==0
 503                    || strcmp(u.sysname,"Darwin")==0) {
 504             st->tun_flavour=TUN_FLAVOUR_BSD;
 505         }
 506     }
 507     if (st->tun_flavour==TUN_FLAVOUR_GUESS) {
 508         cfgfatal(loc,"tun","cannot guess which type of TUN is in use; "
 509                  "specify the flavour explicitly\n");
 510     }
 511
 512     if (st->ifconfig_type==TUN_CONFIG_GUESS) {
 513         switch (st->tun_flavour) {
 514         case TUN_FLAVOUR_LINUX:
 515             st->ifconfig_type=TUN_CONFIG_IOCTL;
 516             break;
 517         case TUN_FLAVOUR_BSD:
 518 #if __linux__
 519             /* XXX on Linux we still want TUN_CONFIG_IOCTL.  Perhaps we can
 520                use this on BSD too. */
 521             st->ifconfig_type=TUN_CONFIG_IOCTL;
 522 #else
 523             st->ifconfig_type=TUN_CONFIG_BSD;
 524 #endif
 525             break;
 526         case TUN_FLAVOUR_STREAMS:
 527             st->ifconfig_type=TUN_CONFIG_BSD;
 528             break;
 529         }
 530     }
 531     if (st->route_type==TUN_CONFIG_GUESS)
 532         st->route_type=st->ifconfig_type;
 533
 534     if (st->ifconfig_type==TUN_CONFIG_GUESS) {
 535         cfgfatal(loc,"tun","cannot guess which ifconfig method to use\n");
 536     }
 537     if (st->route_type==TUN_CONFIG_GUESS) {
 538         cfgfatal(loc,"tun","cannot guess which route method to use\n");
 539     }
 540
 541     if (st->ifconfig_type==TUN_CONFIG_IOCTL && st->ifconfig_path) {
 542         cfgfatal(loc,"tun","ifconfig-type \"ioctl\" is incompatible with "
 543                  "ifconfig-path\n");
 544     }
 545     if (st->route_type==TUN_CONFIG_IOCTL && st->route_path) {
 546         cfgfatal(loc,"tun","route-type \"ioctl\" is incompatible with "
 547                  "route-path\n");
 548     }
 549
 550     Message(M_DEBUG_CONFIG,"%s: tun flavour %s\n",st->nl.name,
 551             tun_flavour_str(st->tun_flavour));
 552     switch (st->tun_flavour) {
 553     case TUN_FLAVOUR_BSD:
 554         if (!st->device_path) st->device_path="/dev/tun";
 555         break;
 556     case TUN_FLAVOUR_LINUX:
 557         if (!st->device_path) st->device_path="/dev/net/tun";
 558         break;
 559     case TUN_FLAVOUR_STREAMS:
 560         if (!st->device_path) st->device_path="/dev/tun";
 561         if (st->interface_name) cfgfatal(loc,"tun","interface name cannot "
 562                                          "be specified with STREAMS TUN\n");
 563         break;
 564     }
 565
 566     if (!st->ip_path) st->ip_path="/dev/ip";
 567     if (!st->ifconfig_path) st->ifconfig_path="ifconfig";
 568     if (!st->route_path) st->route_path="route";
 569
 570 #ifndef HAVE_TUN_STREAMS
 571     if (st->tun_flavour==TUN_FLAVOUR_STREAMS) {
 572         cfgfatal(loc,"tun","TUN flavour STREAMS unsupported in this build "
 573                  "of secnet\n");
 574     }
 575 #endif
 576 #ifndef LINUX_TUN_SUPPORTED
 577     if (st->tun_flavour==TUN_FLAVOUR_LINUX) {
 578         cfgfatal(loc,"tun","TUN flavour LINUX unsupported in this build "
 579                  "of secnet\n");
 580     }
 581 #endif
 582
 583     /* Old TUN interface: the network interface name depends on which
 584        /dev/tunX file we open. If 'interface-search' is set to true, treat
 585        'device' as the prefix and try numbers from 0--255. If it's set
 586        to false, treat 'device' as the whole name, and require than an
 587        appropriate interface name be specified. */
 588     if (st->tun_flavour==TUN_FLAVOUR_BSD) {
 589         if (st->search_for_if && st->interface_name) {
 590             cfgfatal(loc,"tun","you may not specify an interface name "
 591                      "in interface-search mode\n");
 592         }
 593         if (!st->search_for_if && !st->interface_name) {
 594             cfgfatal(loc,"tun","you must specify an interface name "
 595                      "when you explicitly specify a TUN device file\n");
 596         }
 597     }
 598
 599     add_hook(PHASE_GETRESOURCES,tun_phase_hook,st);
 600
 601     return new_closure(&st->nl.cl);
 602 }
 603
 604 static list_t *tun_apply(closure_t *self, struct cloc loc, dict_t *context,
 605                          list_t *args)
 606 {
 607     return tun_create(self,loc,context,args,TUN_FLAVOUR_GUESS);
 608 }
 609
 610 static list_t *tun_bsd_apply(closure_t *self, struct cloc loc, dict_t *context,
 611                              list_t *args)
 612 {
 613     Message(M_WARNING,"(%s,%d): obsolete use of tun-old; replace with tun "
 614             "and specify flavour \"bsd\".\n",loc.file,loc.line);
 615     return tun_create(self,loc,context,args,TUN_FLAVOUR_BSD);
 616 }
 617
 618 void tun_module(dict_t *dict)
 619 {
 620     add_closure(dict,"tun",tun_apply);
 621     add_closure(dict,"tun-old",tun_bsd_apply);
 622 }