mdw@git.distorted.org.uk Git - fwd/blob - inet.c

   1 /* -*-c-*-
   2  *
   3  * Protocol specific definitions for IPv4 sockets
   4  *
   5  * (c) 1999 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the `fwd' port forwarder.
  11  *
  12  * `fwd' is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * `fwd' is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with `fwd'; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 #include "fwd.h"
  28
  29 /*----- Data structures ---------------------------------------------------*/
  30
  31 typedef struct inet_addrx {
  32   addr a;
  33   struct sockaddr_in sin;
  34 } inet_addrx;
  35
  36 typedef struct inet_opts {
  37   addr_opts ao;
  38   struct in_addr bind;
  39 } inet_opts;
  40
  41 typedef struct inet_srcopts {
  42   inet_opts io;
  43   acl_entry *acl;
  44   acl_entry **acltail;
  45 } inet_srcopts;
  46
  47 typedef struct inet_targopts {
  48   inet_opts io;
  49   int ipriv;
  50 } inet_targopts;
  51
  52 #define ADDRF_PRIVCONN 16u
  53
  54 static inet_srcopts inet_globalsrc =
  55   { { { 0 }, { INADDR_ANY } }, 0, &inet_globalsrc.acl };
  56 static inet_targopts inet_globaltarg =
  57   { { { 0 }, { INADDR_ANY } } };
  58
  59 /*----- Protocol operations -----------------------------------------------*/
  60
  61 /* --- @read@ --- */
  62
  63 static addr *inet_read(scanner *sc, unsigned type)
  64 {
  65   inet_addrx *ia = xmalloc(sizeof(*ia));
  66
  67   ia->a.ops = &inet_ops;
  68   ia->a.sz = sizeof(struct sockaddr_in);
  69   memset(&ia->sin, 0, sizeof(ia->sin));
  70   ia->sin.sin_family = AF_INET;
  71
  72   /* --- Read the host address part --- */
  73
  74   switch (type) {
  75     case ADDR_SRC:
  76       if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "port") == 0)
  77         token(sc);
  78       ia->sin.sin_addr.s_addr = htonl(INADDR_ANY);
  79       break;
  80     case ADDR_DEST: {
  81       struct hostent *h;
  82       dstr d = DSTR_INIT;
  83       conf_name(sc, '.', &d);
  84       if ((h = gethostbyname(d.buf)) == 0)
  85         error(sc, "couldn't resolve Internet address `%s'", d.buf);
  86       memcpy(&ia->sin.sin_addr, h->h_addr, sizeof(struct in_addr));
  87       dstr_destroy(&d);
  88       if (sc->t == ':')
  89         token(sc);
  90     } break;
  91   }
  92
  93   /* --- Read the port number --- */
  94
  95   {
  96     struct servent *s;
  97
  98     if (sc->t != CTOK_WORD)
  99       error(sc, "parse error, TCP port expected");
 100     if (isdigit((unsigned char)sc->d.buf[0]))
 101       ia->sin.sin_port = htons(atoi(sc->d.buf));
 102     else if ((s = getservbyname(sc->d.buf, "tcp")) == 0)
 103       error(sc, "unknown tcp service `%s'", sc->d.buf);
 104     else
 105       ia->sin.sin_port = s->s_port;
 106     token(sc);
 107   }
 108
 109   return (&ia->a);
 110 }
 111
 112 /* --- @destroy@ --- */
 113
 114 static void inet_destroy(addr *a)
 115 {
 116   inet_addrx *ia = (inet_addrx *)a;
 117   DESTROY(ia);
 118 }
 119
 120 /* --- @print@ --- */
 121
 122 static void inet_print(addr *a, unsigned type, dstr *d)
 123 {
 124   inet_addrx *ia = (inet_addrx *)a;
 125   switch (type) {
 126     case ADDR_SRC:
 127       dstr_putf(d, "inet:%u", (unsigned)ntohs(ia->sin.sin_port));
 128       break;
 129     case ADDR_DEST:
 130       dstr_putf(d, "inet:%s:%u",
 131                 inet_ntoa(ia->sin.sin_addr),
 132                 (unsigned)ntohs(ia->sin.sin_port));
 133       break;
 134   }
 135 }
 136
 137 /* --- @initopts@ --- */
 138
 139 static addr_opts *inet_initsrcopts(void)
 140 {
 141   inet_srcopts *io = CREATE(inet_srcopts);
 142   *io = inet_globalsrc;
 143   io->acl = 0;
 144   io->acltail = &io->acl;
 145   return (&io->io.ao);
 146 }
 147
 148 static addr_opts *inet_inittargopts(void)
 149 {
 150   inet_targopts *io = CREATE(inet_targopts);
 151   *io = inet_globaltarg;
 152   io->ipriv = -1;
 153   return (&io->io.ao);
 154 }
 155
 156 /* --- @option@ --- */
 157
 158 static void addropt(scanner *sc, inet_opts *io)
 159 {
 160   dstr d = DSTR_INIT;
 161   struct hostent *h;
 162
 163   token(sc);
 164   if (sc->t == '=')
 165     token(sc);
 166   if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "any") == 0)
 167     io->bind.s_addr = INADDR_ANY;
 168   else {
 169     conf_name(sc, '.', &d);
 170     if ((h = gethostbyname(d.buf)) == 0)
 171       error(sc, "couldn't resolve address `%s'", d.buf);
 172     memcpy(&io->bind, h->h_addr, sizeof(struct in_addr));
 173   }
 174 }
 175
 176 static int srcopt(scanner *sc, addr_opts *ao)
 177 {
 178   inet_srcopts *io = (inet_srcopts *)ao;
 179   unsigned act;
 180
 181   CONF_BEGIN(sc, "source", "Internet socket source")
 182
 183   /* --- Initialization --- */
 184
 185   if (!io) {
 186     if (!inet_globalsrc.acltail)
 187       inet_globalsrc.acltail = &inet_globalsrc.acl;
 188     io = &inet_globalsrc;
 189   }
 190
 191   /* --- Source address configuration --- */
 192
 193   if (strcmp(sc->d.buf, "addr") == 0) {
 194     addropt(sc, &io->io);
 195     CONF_ACCEPT;
 196   }
 197
 198   /* --- Access control limitations --- */
 199
 200   if ((strcmp(sc->d.buf, "allow") == 0 && (act = ACL_ALLOW, 1)) ||
 201        (strcmp(sc->d.buf, "deny") == 0 && (act = ACL_DENY, 1))) {
 202     struct hostent *h;
 203     struct netent *n;
 204     struct in_addr a, m;
 205     dstr d = DSTR_INIT;
 206
 207     /* --- Find out what's going on --- */
 208
 209     token(sc);
 210     if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "from") == 0)
 211       token(sc);
 212
 213     if (sc->t == CTOK_WORD && (strcmp(sc->d.buf, "priv") == 0 ||
 214                                strcmp(sc->d.buf, "priv-port") == 0)) {
 215       acl_addpriv(&io->acltail, act);
 216       token(sc);
 217     } else {
 218       if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "host") == 0)
 219         token(sc);
 220
 221       /* --- Find the host or network address --- */
 222
 223       conf_name(sc, '.', &d);
 224 #ifdef HAVE_GETNETBYNAME
 225       if ((n = getnetbyname(d.buf)) != 0)
 226         a.s_addr = htonl(n->n_net);
 227       else
 228 #endif
 229         if ((h = gethostbyname(d.buf)) == 0)
 230           error(sc, "couldn't resolve address `%s'", d.buf);
 231         else
 232           memcpy(&a, h->h_addr, sizeof(struct in_addr));
 233
 234       /* --- Find the netmask, if any --- */
 235
 236       if (sc->t != '/')
 237         m.s_addr = ~0ul;
 238       else {
 239         token(sc);
 240         DRESET(&d);
 241         conf_name(sc, '.', &d);
 242         if (strchr(d.buf, '.') == 0) {
 243           int n = atoi(d.buf);
 244           if (n == 0)
 245             m.s_addr = 0;
 246           else
 247             m.s_addr = htonl((~0ul << (32 - n)) & 0xffffffff);
 248         } else {
 249 #ifdef HAVE_INET_ATON
 250           if (!inet_aton(d.buf, &m))
 251             error(sc, "bad netmask `%s'", d.buf);
 252 #else
 253           m.s_addr = inet_addr(d.buf);
 254 #endif
 255         }
 256       }
 257       dstr_destroy(&d);
 258
 259       /* --- Add the access control entry --- */
 260
 261       acl_addhost(&io->acltail, act, a, m);
 262     }
 263     CONF_ACCEPT;
 264   }
 265
 266   /* --- Anything unrecognized --- */
 267
 268   CONF_END;
 269 }
 270
 271 static int targopt(scanner *sc, addr_opts *ao)
 272 {
 273   inet_targopts *io = (inet_targopts *)ao;
 274
 275   CONF_BEGIN(sc, "dest", "Internet socket target");
 276   if (strcmp(sc->d.buf, "addr") == 0) {
 277     addropt(sc, &io->io);
 278     CONF_ACCEPT;
 279   }
 280   if (strcmp(sc->d.buf, "priv") == 0 ||
 281       strcmp(sc->d.buf, "priv-port") == 0) {
 282     token(sc);
 283     if (sc->t == '=') token(sc);
 284     if (conf_enum(sc, "no,yes", ENUM_ABBREV, "privileged connection status"))
 285       io->io.ao.f |= ADDRF_PRIVCONN;
 286     else
 287       io->io.ao.f &= ~ADDRF_PRIVCONN;
 288     CONF_ACCEPT;
 289   }
 290   CONF_END;
 291 }
 292
 293 static int inet_option(scanner *sc, addr_opts *ao, unsigned type)
 294 {
 295   CONF_BEGIN(sc, "inet", "Internet socket");
 296   if (type != ADDR_DEST && srcopt(sc, ao))
 297     CONF_ACCEPT;
 298   if (type != ADDR_SRC && targopt(sc, ao))
 299     CONF_ACCEPT;
 300   CONF_END;
 301 }
 302
 303 /* --- @confirm@ --- */
 304
 305 static void inet_confirm(addr *a, unsigned type, addr_opts *ao)
 306 {
 307   inet_addrx *ia = (inet_addrx *)a;
 308
 309   switch (type) {
 310     case ADDR_DEST: {
 311       inet_targopts *io = (inet_targopts *)ao;
 312       if ((io->io.ao.f & ADDRF_PRIVCONN) &&
 313           (io->ipriv = privconn_adddest(ia->sin.sin_addr,
 314                                         ia->sin.sin_port)) < 0)
 315         die(1, "couldn't add privileged connection target (too late)");
 316     } break;
 317   }
 318 }
 319
 320 /* --- @freeopts@ --- */
 321
 322 static void inet_freesrcopts(addr_opts *ao)
 323 {
 324   inet_srcopts *io = (inet_srcopts *)ao;
 325   acl_free(io->acl);
 326   DESTROY(io);
 327 }
 328
 329 static void inet_freetargopts(addr_opts *ao)
 330 {
 331   inet_targopts *io = (inet_targopts *)ao;
 332   DESTROY(io);
 333 }
 334
 335 /* --- @bind@ --- */
 336
 337 static int inet_bind(addr *a, addr_opts *ao)
 338 {
 339   inet_addrx *ia = (inet_addrx *)a;
 340   inet_srcopts *io = (inet_srcopts *)ao;
 341   struct sockaddr_in sin;
 342   int opt = 1;
 343   int fd;
 344
 345   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
 346     goto fail_0;
 347   setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
 348   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 349   sin = ia->sin;
 350   sin.sin_addr = io->io.bind;
 351   if (bind(fd, (struct sockaddr *)&sin, sizeof(ia->sin)))
 352     goto fail_1;
 353   return (fd);
 354
 355 fail_1:
 356   close(fd);
 357 fail_0:
 358   return (-1);
 359 }
 360
 361 /* --- @accept@ --- */
 362
 363 static reffd *inet_accept(int fd, addr_opts *ao, const char *desc)
 364 {
 365   inet_srcopts *io = (inet_srcopts *)ao;
 366   int nfd;
 367   id_req q;
 368   size_t lsinsz = sizeof(q.lsin), rsinsz = sizeof(q.rsin);
 369   int act = ACL_ALLOW;
 370
 371   /* --- Accept the new connection --- */
 372
 373   if ((nfd = accept(fd, (struct sockaddr *)&q.rsin, &rsinsz)) < 0)
 374     return (0);
 375   if (getsockname(nfd, (struct sockaddr *)&q.lsin, &lsinsz)) {
 376     close(nfd);
 377     return (0);
 378   }
 379   q.desc = desc;
 380   q.r = reffd_init(nfd);
 381
 382   /* --- Find out whether this connection is allowed --- */
 383
 384   if (!acl_check(io->acl, q.rsin.sin_addr, ntohs(q.rsin.sin_port), &act))
 385     acl_check(inet_globalsrc.acl, q.rsin.sin_addr,
 386               ntohs(q.rsin.sin_port), &act);
 387   if (act != ACL_ALLOW) {
 388     q.act = "refused";
 389     if (!(io->io.ao.f & ADDRF_NOLOG))
 390       identify(&q);
 391     REFFD_DEC(q.r);
 392     return (0);
 393   }
 394
 395   /* --- Everything seems to be OK --- */
 396
 397   q.act = "accepted";
 398   if (!(io->io.ao.f & ADDRF_NOLOG))
 399     identify(&q);
 400   return (q.r);
 401 }
 402
 403 /* --- @connect@ --- */
 404
 405 static int inet_connect(addr *a, addr_opts *ao, conn *c, endpt *e)
 406 {
 407   inet_addrx *ia = (inet_addrx *)a;
 408   inet_targopts *io = (inet_targopts *)ao;
 409   int fd;
 410
 411   if (io->ipriv >= 0) {
 412     return (privconn_connect(c, sel, io->ipriv, io->io.bind,
 413                              starget_connected, e));
 414   }
 415   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
 416     goto fail_0;
 417   if (io->io.bind.s_addr != INADDR_ANY) {
 418     struct sockaddr_in sin;
 419     memset(&sin, 0, sizeof(sin));
 420     sin.sin_family = AF_INET;
 421     sin.sin_addr = io->io.bind;
 422     sin.sin_port = 0;
 423     if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)))
 424       goto fail_1;
 425   }
 426   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 427   return (conn_init(c, sel, fd, (struct sockaddr *)&ia->sin, sizeof(ia->sin),
 428                     starget_connected, e));
 429 fail_1:
 430   close(fd);
 431 fail_0:
 432   return (-1);
 433 }
 434
 435 /* --- Ops table --- */
 436
 437 addr_ops inet_ops = {
 438   "inet",
 439   inet_read, inet_destroy, inet_print,
 440   inet_initsrcopts, inet_option, inet_confirm, inet_freesrcopts,
 441   inet_bind, 0, inet_accept,
 442   inet_inittargopts, inet_freetargopts,
 443   inet_connect
 444 };
 445
 446 /*----- That's all, folks -------------------------------------------------*/