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

   1 /* -*-c-*-
   2  *
   3  * $Id: inet.c,v 1.5 2003/11/25 14:08:23 mdw Exp $
   4  *
   5  * Protocol specific definitions for IPv4 sockets
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `fw' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: inet.c,v $
  32  * Revision 1.5  2003/11/25 14:08:23  mdw
  33  * Debianization.  Socket target options.  Internet binding.
  34  *
  35  * Revision 1.4  2002/01/13 14:49:56  mdw
  36  * Conditional compilation for @getnetbyname@, since Cygwin doesn't have
  37  * it.
  38  *
  39  * Revision 1.3  2000/08/01 17:59:56  mdw
  40  * Switch over to using `size_t' for socket address lengths.
  41  *
  42  * Revision 1.2  1999/07/27 18:30:53  mdw
  43  * Various minor portability fixes.
  44  *
  45  * Revision 1.1  1999/07/26 23:34:11  mdw
  46  * New socket address types.
  47  *
  48  */
  49
  50 /*----- Header files ------------------------------------------------------*/
  51
  52 #include "config.h"
  53
  54 #include <ctype.h>
  55 #include <errno.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59
  60 #include <sys/types.h>
  61 #include <unistd.h>
  62
  63 #include <sys/socket.h>
  64 #include <netinet/in.h>
  65 #include <arpa/inet.h>
  66 #include <netdb.h>
  67
  68 #include <mLib/alloc.h>
  69 #include <mLib/dstr.h>
  70 #include <mLib/fdflags.h>
  71 #include <mLib/report.h>
  72 #include <mLib/sub.h>
  73
  74 #include "acl.h"
  75 #include "addr.h"
  76 #include "conf.h"
  77 #include "fw.h"
  78 #include "identify.h"
  79 #include "inet.h"
  80 #include "reffd.h"
  81 #include "scan.h"
  82 #include "socket.h"
  83
  84 /*----- Data structures ---------------------------------------------------*/
  85
  86 typedef struct inet_addrx {
  87   addr a;
  88   struct sockaddr_in sin;
  89 } inet_addrx;
  90
  91 typedef struct inet_opts {
  92   addr_opts ao;
  93   struct in_addr bind;
  94 } inet_opts;
  95
  96 typedef struct inet_srcopts {
  97   inet_opts io;
  98   acl_entry *acl;
  99   acl_entry **acltail;
 100 } inet_srcopts;
 101
 102 typedef struct inet_targopts {
 103   inet_opts io;
 104 } inet_targopts;
 105
 106 static inet_srcopts inet_globalsrc =
 107   { { { 0 }, { INADDR_ANY } }, 0, &inet_globalsrc.acl };
 108 static inet_targopts inet_globaltarg =
 109   { { { 0 }, { INADDR_ANY } } };
 110
 111 /*----- Protocol operations -----------------------------------------------*/
 112
 113 /* --- @read@ --- */
 114
 115 static addr *inet_read(scanner *sc, unsigned type)
 116 {
 117   inet_addrx *ia = xmalloc(sizeof(*ia));
 118
 119   ia->a.ops = &inet_ops;
 120   ia->a.sz = sizeof(struct sockaddr_in);
 121   memset(&ia->sin, 0, sizeof(ia->sin));
 122   ia->sin.sin_family = AF_INET;
 123
 124   /* --- Read the host address part --- */
 125
 126   switch (type) {
 127     case ADDR_SRC:
 128       if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "port") == 0)
 129         token(sc);
 130       ia->sin.sin_addr.s_addr = htonl(INADDR_ANY);
 131       break;
 132     case ADDR_DEST: {
 133       struct hostent *h;
 134       dstr d = DSTR_INIT;
 135       conf_name(sc, '.', &d);
 136       if ((h = gethostbyname(d.buf)) == 0)
 137         error(sc, "couldn't resolve Internet address `%s'", d.buf);
 138       memcpy(&ia->sin.sin_addr, h->h_addr, sizeof(struct in_addr));
 139       dstr_destroy(&d);
 140       if (sc->t == ':')
 141         token(sc);
 142     } break;
 143   }
 144
 145   /* --- Read the port number --- */
 146
 147   {
 148     struct servent *s;
 149
 150     if (sc->t != CTOK_WORD)
 151       error(sc, "parse error, TCP port expected");
 152     if (isdigit((unsigned char)sc->d.buf[0]))
 153       ia->sin.sin_port = htons(atoi(sc->d.buf));
 154     else if ((s = getservbyname(sc->d.buf, "tcp")) == 0)
 155       error(sc, "unknown tcp service `%s'", sc->d.buf);
 156     else
 157       ia->sin.sin_port = s->s_port;
 158     token(sc);
 159   }
 160
 161   return (&ia->a);
 162 }
 163
 164 /* --- @destroy@ --- */
 165
 166 static void inet_destroy(addr *a)
 167 {
 168   inet_addrx *ia = (inet_addrx *)a;
 169   DESTROY(ia);
 170 }
 171
 172 /* --- @print@ --- */
 173
 174 static void inet_print(addr *a, unsigned type, dstr *d)
 175 {
 176   inet_addrx *ia = (inet_addrx *)a;
 177   switch (type) {
 178     case ADDR_SRC:
 179       dstr_putf(d, "inet:%u", (unsigned)ntohs(ia->sin.sin_port));
 180       break;
 181     case ADDR_DEST:
 182       dstr_putf(d, "inet:%s:%u",
 183                 inet_ntoa(ia->sin.sin_addr),
 184                 (unsigned)ntohs(ia->sin.sin_port));
 185       break;
 186   }
 187 }
 188
 189 /* --- @initopts@ --- */
 190
 191 static addr_opts *inet_initsrcopts(void)
 192 {
 193   inet_srcopts *io = CREATE(inet_srcopts);
 194   *io = inet_globalsrc;
 195   io->acl = 0;
 196   io->acltail = &io->acl;
 197   return (&io->io.ao);
 198 }
 199
 200 static addr_opts *inet_inittargopts(void)
 201 {
 202   inet_targopts *io = CREATE(inet_targopts);
 203   *io = inet_globaltarg;
 204   return (&io->io.ao);
 205 }
 206
 207 /* --- @option@ --- */
 208
 209 static void addropt(scanner *sc, inet_opts *io)
 210 {
 211   dstr d = DSTR_INIT;
 212   struct hostent *h;
 213
 214   token(sc);
 215   if (sc->t == '=')
 216     token(sc);
 217   if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "any") == 0)
 218     io->bind.s_addr = INADDR_ANY;
 219   else {
 220     conf_name(sc, '.', &d);
 221     if ((h = gethostbyname(d.buf)) == 0)
 222       error(sc, "couldn't resolve address `%s'", d.buf);
 223     memcpy(&io->bind, h->h_addr, sizeof(struct in_addr));
 224   }
 225 }
 226
 227 static int srcopt(scanner *sc, addr_opts *ao)
 228 {
 229   inet_srcopts *io = (inet_srcopts *)ao;
 230   unsigned act;
 231
 232   CONF_BEGIN(sc, "source", "Internet socket source")
 233
 234   /* --- Initialization --- */
 235
 236   if (!io) {
 237     if (!inet_globalsrc.acltail)
 238       inet_globalsrc.acltail = &inet_globalsrc.acl;
 239     io = &inet_globalsrc;
 240   }
 241
 242   /* --- Source address configuration --- */
 243
 244   if (strcmp(sc->d.buf, "addr") == 0) {
 245     addropt(sc, &io->io);
 246     CONF_ACCEPT;
 247   }
 248
 249   /* --- Access control limitations --- */
 250
 251   if ((strcmp(sc->d.buf, "allow") == 0 && (act = ACL_ALLOW, 1)) ||
 252        (strcmp(sc->d.buf, "deny") == 0 && (act = ACL_DENY, 1))) {
 253     struct hostent *h;
 254     struct netent *n;
 255     struct in_addr a, m;
 256     dstr d = DSTR_INIT;
 257
 258     /* --- Find out what's going on --- */
 259
 260     token(sc);
 261     if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "from") == 0)
 262       token(sc);
 263
 264     if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "priv-port") == 0) {
 265       acl_addpriv(&io->acltail, act);
 266       token(sc);
 267     } else {
 268       if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "host") == 0)
 269         token(sc);
 270
 271       /* --- Find the host or network address --- */
 272
 273       conf_name(sc, '.', &d);
 274 #ifdef HAVE_GETNETBYNAME
 275       if ((n = getnetbyname(d.buf)) != 0)
 276         a.s_addr = htonl(n->n_net);
 277       else
 278 #endif
 279         if ((h = gethostbyname(d.buf)) == 0)
 280           error(sc, "couldn't resolve address `%s'", d.buf);
 281         else
 282           memcpy(&a, h->h_addr, sizeof(struct in_addr));
 283
 284       /* --- Find the netmask, if any --- */
 285
 286       if (sc->t != '/')
 287         m.s_addr = ~0ul;
 288       else {
 289         token(sc);
 290         DRESET(&d);
 291         conf_name(sc, '.', &d);
 292         if (strchr(d.buf, '.') == 0) {
 293           int n = atoi(d.buf);
 294           if (n == 0)
 295             m.s_addr = 0;
 296           else
 297             m.s_addr = htonl((~0ul << (32 - n)) & 0xffffffff);
 298         } else {
 299 #ifdef HAVE_INET_ATON
 300           if (!inet_aton(d.buf, &m))
 301             error(sc, "bad netmask `%s'", d.buf);
 302 #else
 303           m.s_addr = inet_addr(d.buf);
 304 #endif
 305         }
 306       }
 307       dstr_destroy(&d);
 308
 309       /* --- Add the access control entry --- */
 310
 311       acl_addhost(&io->acltail, act, a, m);
 312     }
 313     CONF_ACCEPT;
 314   }
 315
 316   /* --- Anything unrecognized --- */
 317
 318   CONF_END;
 319 }
 320
 321 static int targopt(scanner *sc, addr_opts *ao)
 322 {
 323   inet_targopts *io = (inet_targopts *)ao;
 324
 325   CONF_BEGIN(sc, "dest", "Internet socket target");
 326   if (strcmp(sc->d.buf, "addr") == 0) {
 327     addropt(sc, &io->io);
 328     CONF_ACCEPT;
 329   }
 330   CONF_END;
 331 }
 332
 333 static int inet_option(scanner *sc, addr_opts *ao, unsigned type)
 334 {
 335   CONF_BEGIN(sc, "inet", "Internet socket");
 336   if (type != ADDR_DEST && srcopt(sc, ao))
 337     CONF_ACCEPT;
 338   if (type != ADDR_SRC && targopt(sc, ao))
 339     CONF_ACCEPT;
 340   CONF_END;
 341 }
 342
 343 /* --- @freeopts@ --- */
 344
 345 static void inet_freesrcopts(addr_opts *ao)
 346 {
 347   inet_srcopts *io = (inet_srcopts *)ao;
 348   acl_free(io->acl);
 349   DESTROY(io);
 350 }
 351
 352 static void inet_freetargopts(addr_opts *ao)
 353 {
 354   inet_targopts *io = (inet_targopts *)ao;
 355   DESTROY(io);
 356 }
 357
 358 /* --- @bind@ --- */
 359
 360 static int inet_bind(addr *a, addr_opts *ao)
 361 {
 362   inet_addrx *ia = (inet_addrx *)a;
 363   inet_srcopts *io = (inet_srcopts *)ao;
 364   struct sockaddr_in sin;
 365   int opt = 1;
 366   int fd;
 367
 368   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
 369     goto fail_0;
 370   setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
 371   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 372   sin = ia->sin;
 373   sin.sin_addr = io->io.bind;
 374   if (bind(fd, (struct sockaddr *)&sin, sizeof(ia->sin)))
 375     goto fail_1;
 376   return (fd);
 377
 378 fail_1:
 379   close(fd);
 380 fail_0:
 381   return (-1);
 382 }
 383
 384 /* --- @accept@ --- */
 385
 386 static reffd *inet_accept(int fd, addr_opts *ao, const char *desc)
 387 {
 388   inet_srcopts *io = (inet_srcopts *)ao;
 389   int nfd;
 390   id_req q;
 391   size_t lsinsz = sizeof(q.lsin), rsinsz = sizeof(q.rsin);
 392   int act = ACL_ALLOW;
 393
 394   /* --- Accept the new connection --- */
 395
 396   if ((nfd = accept(fd, (struct sockaddr *)&q.rsin, &rsinsz)) < 0)
 397     return (0);
 398   if (getsockname(nfd, (struct sockaddr *)&q.lsin, &lsinsz)) {
 399     close(nfd);
 400     return (0);
 401   }
 402   q.desc = desc;
 403   q.r = reffd_init(nfd);
 404
 405   /* --- Find out whether this connection is allowed --- */
 406
 407   if (!acl_check(io->acl, q.rsin.sin_addr, ntohs(q.rsin.sin_port), &act))
 408     acl_check(inet_globalsrc.acl, q.rsin.sin_addr,
 409               ntohs(q.rsin.sin_port), &act);
 410   if (act != ACL_ALLOW) {
 411     q.act = "refused";
 412     if (!(io->io.ao.f & ADDRF_NOLOG))
 413       identify(&q);
 414     REFFD_DEC(q.r);
 415     return (0);
 416   }
 417
 418   /* --- Everything seems to be OK --- */
 419
 420   q.act = "accepted";
 421   if (!(io->io.ao.f & ADDRF_NOLOG))
 422     identify(&q);
 423   return (q.r);
 424 }
 425
 426 /* --- @connect@ --- */
 427
 428 static int inet_connect(addr *a, addr_opts *ao, conn *c, endpt *e)
 429 {
 430   inet_addrx *ia = (inet_addrx *)a;
 431   inet_targopts *io = (inet_targopts *)ao;
 432   int fd;
 433
 434   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
 435     goto fail_0;
 436   if (io->io.bind.s_addr != INADDR_ANY) {
 437     struct sockaddr_in sin;
 438     memset(&sin, 0, sizeof(sin));
 439     sin.sin_family = AF_INET;
 440     sin.sin_addr = io->io.bind;
 441     sin.sin_port = 0;
 442     if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)))
 443       goto fail_1;
 444   }
 445   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 446   return (conn_init(c, sel, fd, (struct sockaddr *)&ia->sin, sizeof(ia->sin),
 447                     starget_connected, e));
 448 fail_1:
 449   close(fd);
 450 fail_0:
 451   return (-1);
 452 }
 453
 454 /* --- Ops table --- */
 455
 456 addr_ops inet_ops = {
 457   "inet",
 458   inet_read, inet_destroy, inet_print,
 459   inet_initsrcopts, inet_option, inet_freesrcopts,
 460   inet_bind, 0, inet_accept,
 461   inet_inittargopts, inet_freetargopts,
 462   inet_connect
 463 };
 464
 465 /*----- That's all, folks -------------------------------------------------*/