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

   1 /* -*-c-*-
   2  *
   3  * $Id: inet.c,v 1.7 2004/04/08 01:36:25 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 /*----- Header files ------------------------------------------------------*/
  30
  31 #include "config.h"
  32
  33 #include <ctype.h>
  34 #include <errno.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 #include <sys/types.h>
  40 #include <unistd.h>
  41
  42 #include <sys/socket.h>
  43 #include <netinet/in.h>
  44 #include <arpa/inet.h>
  45 #include <netdb.h>
  46
  47 #include <mLib/alloc.h>
  48 #include <mLib/dstr.h>
  49 #include <mLib/fdflags.h>
  50 #include <mLib/report.h>
  51 #include <mLib/sub.h>
  52
  53 #include "acl.h"
  54 #include "addr.h"
  55 #include "conf.h"
  56 #include "fw.h"
  57 #include "identify.h"
  58 #include "inet.h"
  59 #include "privconn.h"
  60 #include "reffd.h"
  61 #include "scan.h"
  62 #include "socket.h"
  63
  64 /*----- Data structures ---------------------------------------------------*/
  65
  66 typedef struct inet_addrx {
  67   addr a;
  68   struct sockaddr_in sin;
  69 } inet_addrx;
  70
  71 typedef struct inet_opts {
  72   addr_opts ao;
  73   struct in_addr bind;
  74 } inet_opts;
  75
  76 typedef struct inet_srcopts {
  77   inet_opts io;
  78   acl_entry *acl;
  79   acl_entry **acltail;
  80 } inet_srcopts;
  81
  82 typedef struct inet_targopts {
  83   inet_opts io;
  84   int ipriv;
  85 } inet_targopts;
  86
  87 #define ADDRF_PRIVCONN 16u
  88
  89 static inet_srcopts inet_globalsrc =
  90   { { { 0 }, { INADDR_ANY } }, 0, &inet_globalsrc.acl };
  91 static inet_targopts inet_globaltarg =
  92   { { { 0 }, { INADDR_ANY } } };
  93
  94 /*----- Protocol operations -----------------------------------------------*/
  95
  96 /* --- @read@ --- */
  97
  98 static addr *inet_read(scanner *sc, unsigned type)
  99 {
 100   inet_addrx *ia = xmalloc(sizeof(*ia));
 101
 102   ia->a.ops = &inet_ops;
 103   ia->a.sz = sizeof(struct sockaddr_in);
 104   memset(&ia->sin, 0, sizeof(ia->sin));
 105   ia->sin.sin_family = AF_INET;
 106
 107   /* --- Read the host address part --- */
 108
 109   switch (type) {
 110     case ADDR_SRC:
 111       if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "port") == 0)
 112         token(sc);
 113       ia->sin.sin_addr.s_addr = htonl(INADDR_ANY);
 114       break;
 115     case ADDR_DEST: {
 116       struct hostent *h;
 117       dstr d = DSTR_INIT;
 118       conf_name(sc, '.', &d);
 119       if ((h = gethostbyname(d.buf)) == 0)
 120         error(sc, "couldn't resolve Internet address `%s'", d.buf);
 121       memcpy(&ia->sin.sin_addr, h->h_addr, sizeof(struct in_addr));
 122       dstr_destroy(&d);
 123       if (sc->t == ':')
 124         token(sc);
 125     } break;
 126   }
 127
 128   /* --- Read the port number --- */
 129
 130   {
 131     struct servent *s;
 132
 133     if (sc->t != CTOK_WORD)
 134       error(sc, "parse error, TCP port expected");
 135     if (isdigit((unsigned char)sc->d.buf[0]))
 136       ia->sin.sin_port = htons(atoi(sc->d.buf));
 137     else if ((s = getservbyname(sc->d.buf, "tcp")) == 0)
 138       error(sc, "unknown tcp service `%s'", sc->d.buf);
 139     else
 140       ia->sin.sin_port = s->s_port;
 141     token(sc);
 142   }
 143
 144   return (&ia->a);
 145 }
 146
 147 /* --- @destroy@ --- */
 148
 149 static void inet_destroy(addr *a)
 150 {
 151   inet_addrx *ia = (inet_addrx *)a;
 152   DESTROY(ia);
 153 }
 154
 155 /* --- @print@ --- */
 156
 157 static void inet_print(addr *a, unsigned type, dstr *d)
 158 {
 159   inet_addrx *ia = (inet_addrx *)a;
 160   switch (type) {
 161     case ADDR_SRC:
 162       dstr_putf(d, "inet:%u", (unsigned)ntohs(ia->sin.sin_port));
 163       break;
 164     case ADDR_DEST:
 165       dstr_putf(d, "inet:%s:%u",
 166                 inet_ntoa(ia->sin.sin_addr),
 167                 (unsigned)ntohs(ia->sin.sin_port));
 168       break;
 169   }
 170 }
 171
 172 /* --- @initopts@ --- */
 173
 174 static addr_opts *inet_initsrcopts(void)
 175 {
 176   inet_srcopts *io = CREATE(inet_srcopts);
 177   *io = inet_globalsrc;
 178   io->acl = 0;
 179   io->acltail = &io->acl;
 180   return (&io->io.ao);
 181 }
 182
 183 static addr_opts *inet_inittargopts(void)
 184 {
 185   inet_targopts *io = CREATE(inet_targopts);
 186   *io = inet_globaltarg;
 187   io->ipriv = -1;
 188   return (&io->io.ao);
 189 }
 190
 191 /* --- @option@ --- */
 192
 193 static void addropt(scanner *sc, inet_opts *io)
 194 {
 195   dstr d = DSTR_INIT;
 196   struct hostent *h;
 197
 198   token(sc);
 199   if (sc->t == '=')
 200     token(sc);
 201   if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "any") == 0)
 202     io->bind.s_addr = INADDR_ANY;
 203   else {
 204     conf_name(sc, '.', &d);
 205     if ((h = gethostbyname(d.buf)) == 0)
 206       error(sc, "couldn't resolve address `%s'", d.buf);
 207     memcpy(&io->bind, h->h_addr, sizeof(struct in_addr));
 208   }
 209 }
 210
 211 static int srcopt(scanner *sc, addr_opts *ao)
 212 {
 213   inet_srcopts *io = (inet_srcopts *)ao;
 214   unsigned act;
 215
 216   CONF_BEGIN(sc, "source", "Internet socket source")
 217
 218   /* --- Initialization --- */
 219
 220   if (!io) {
 221     if (!inet_globalsrc.acltail)
 222       inet_globalsrc.acltail = &inet_globalsrc.acl;
 223     io = &inet_globalsrc;
 224   }
 225
 226   /* --- Source address configuration --- */
 227
 228   if (strcmp(sc->d.buf, "addr") == 0) {
 229     addropt(sc, &io->io);
 230     CONF_ACCEPT;
 231   }
 232
 233   /* --- Access control limitations --- */
 234
 235   if ((strcmp(sc->d.buf, "allow") == 0 && (act = ACL_ALLOW, 1)) ||
 236        (strcmp(sc->d.buf, "deny") == 0 && (act = ACL_DENY, 1))) {
 237     struct hostent *h;
 238     struct netent *n;
 239     struct in_addr a, m;
 240     dstr d = DSTR_INIT;
 241
 242     /* --- Find out what's going on --- */
 243
 244     token(sc);
 245     if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "from") == 0)
 246       token(sc);
 247
 248     if (sc->t == CTOK_WORD && (strcmp(sc->d.buf, "priv") == 0 ||
 249                                strcmp(sc->d.buf, "priv-port") == 0)) {
 250       acl_addpriv(&io->acltail, act);
 251       token(sc);
 252     } else {
 253       if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "host") == 0)
 254         token(sc);
 255
 256       /* --- Find the host or network address --- */
 257
 258       conf_name(sc, '.', &d);
 259 #ifdef HAVE_GETNETBYNAME
 260       if ((n = getnetbyname(d.buf)) != 0)
 261         a.s_addr = htonl(n->n_net);
 262       else
 263 #endif
 264         if ((h = gethostbyname(d.buf)) == 0)
 265           error(sc, "couldn't resolve address `%s'", d.buf);
 266         else
 267           memcpy(&a, h->h_addr, sizeof(struct in_addr));
 268
 269       /* --- Find the netmask, if any --- */
 270
 271       if (sc->t != '/')
 272         m.s_addr = ~0ul;
 273       else {
 274         token(sc);
 275         DRESET(&d);
 276         conf_name(sc, '.', &d);
 277         if (strchr(d.buf, '.') == 0) {
 278           int n = atoi(d.buf);
 279           if (n == 0)
 280             m.s_addr = 0;
 281           else
 282             m.s_addr = htonl((~0ul << (32 - n)) & 0xffffffff);
 283         } else {
 284 #ifdef HAVE_INET_ATON
 285           if (!inet_aton(d.buf, &m))
 286             error(sc, "bad netmask `%s'", d.buf);
 287 #else
 288           m.s_addr = inet_addr(d.buf);
 289 #endif
 290         }
 291       }
 292       dstr_destroy(&d);
 293
 294       /* --- Add the access control entry --- */
 295
 296       acl_addhost(&io->acltail, act, a, m);
 297     }
 298     CONF_ACCEPT;
 299   }
 300
 301   /* --- Anything unrecognized --- */
 302
 303   CONF_END;
 304 }
 305
 306 static int targopt(scanner *sc, addr_opts *ao)
 307 {
 308   inet_targopts *io = (inet_targopts *)ao;
 309
 310   CONF_BEGIN(sc, "dest", "Internet socket target");
 311   if (strcmp(sc->d.buf, "addr") == 0) {
 312     addropt(sc, &io->io);
 313     CONF_ACCEPT;
 314   }
 315   if (strcmp(sc->d.buf, "priv") == 0 ||
 316       strcmp(sc->d.buf, "priv-port") == 0) {
 317     token(sc);
 318     if (sc->t == '=') token(sc);
 319     if (conf_enum(sc, "no,yes", ENUM_ABBREV, "privileged connection status"))
 320       io->io.ao.f |= ADDRF_PRIVCONN;
 321     else
 322       io->io.ao.f &= ~ADDRF_PRIVCONN;
 323     CONF_ACCEPT;
 324   }
 325   CONF_END;
 326 }
 327
 328 static int inet_option(scanner *sc, addr_opts *ao, unsigned type)
 329 {
 330   CONF_BEGIN(sc, "inet", "Internet socket");
 331   if (type != ADDR_DEST && srcopt(sc, ao))
 332     CONF_ACCEPT;
 333   if (type != ADDR_SRC && targopt(sc, ao))
 334     CONF_ACCEPT;
 335   CONF_END;
 336 }
 337
 338 /* --- @confirm@ --- */
 339
 340 static void inet_confirm(addr *a, unsigned type, addr_opts *ao)
 341 {
 342   inet_addrx *ia = (inet_addrx *)a;
 343
 344   switch (type) {
 345     case ADDR_DEST: {
 346       inet_targopts *io = (inet_targopts *)ao;
 347       if ((io->io.ao.f & ADDRF_PRIVCONN) &&
 348           (io->ipriv = privconn_adddest(ia->sin.sin_addr,
 349                                         ia->sin.sin_port)) < 0)
 350         die(1, "couldn't add privileged connection target (too late)");
 351     } break;
 352   }
 353 }
 354
 355 /* --- @freeopts@ --- */
 356
 357 static void inet_freesrcopts(addr_opts *ao)
 358 {
 359   inet_srcopts *io = (inet_srcopts *)ao;
 360   acl_free(io->acl);
 361   DESTROY(io);
 362 }
 363
 364 static void inet_freetargopts(addr_opts *ao)
 365 {
 366   inet_targopts *io = (inet_targopts *)ao;
 367   DESTROY(io);
 368 }
 369
 370 /* --- @bind@ --- */
 371
 372 static int inet_bind(addr *a, addr_opts *ao)
 373 {
 374   inet_addrx *ia = (inet_addrx *)a;
 375   inet_srcopts *io = (inet_srcopts *)ao;
 376   struct sockaddr_in sin;
 377   int opt = 1;
 378   int fd;
 379
 380   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
 381     goto fail_0;
 382   setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
 383   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 384   sin = ia->sin;
 385   sin.sin_addr = io->io.bind;
 386   if (bind(fd, (struct sockaddr *)&sin, sizeof(ia->sin)))
 387     goto fail_1;
 388   return (fd);
 389
 390 fail_1:
 391   close(fd);
 392 fail_0:
 393   return (-1);
 394 }
 395
 396 /* --- @accept@ --- */
 397
 398 static reffd *inet_accept(int fd, addr_opts *ao, const char *desc)
 399 {
 400   inet_srcopts *io = (inet_srcopts *)ao;
 401   int nfd;
 402   id_req q;
 403   size_t lsinsz = sizeof(q.lsin), rsinsz = sizeof(q.rsin);
 404   int act = ACL_ALLOW;
 405
 406   /* --- Accept the new connection --- */
 407
 408   if ((nfd = accept(fd, (struct sockaddr *)&q.rsin, &rsinsz)) < 0)
 409     return (0);
 410   if (getsockname(nfd, (struct sockaddr *)&q.lsin, &lsinsz)) {
 411     close(nfd);
 412     return (0);
 413   }
 414   q.desc = desc;
 415   q.r = reffd_init(nfd);
 416
 417   /* --- Find out whether this connection is allowed --- */
 418
 419   if (!acl_check(io->acl, q.rsin.sin_addr, ntohs(q.rsin.sin_port), &act))
 420     acl_check(inet_globalsrc.acl, q.rsin.sin_addr,
 421               ntohs(q.rsin.sin_port), &act);
 422   if (act != ACL_ALLOW) {
 423     q.act = "refused";
 424     if (!(io->io.ao.f & ADDRF_NOLOG))
 425       identify(&q);
 426     REFFD_DEC(q.r);
 427     return (0);
 428   }
 429
 430   /* --- Everything seems to be OK --- */
 431
 432   q.act = "accepted";
 433   if (!(io->io.ao.f & ADDRF_NOLOG))
 434     identify(&q);
 435   return (q.r);
 436 }
 437
 438 /* --- @connect@ --- */
 439
 440 static int inet_connect(addr *a, addr_opts *ao, conn *c, endpt *e)
 441 {
 442   inet_addrx *ia = (inet_addrx *)a;
 443   inet_targopts *io = (inet_targopts *)ao;
 444   int fd;
 445
 446   if (io->ipriv >= 0) {
 447     return (privconn_connect(c, sel, io->ipriv, io->io.bind,
 448                              starget_connected, e));
 449   }
 450   if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
 451     goto fail_0;
 452   if (io->io.bind.s_addr != INADDR_ANY) {
 453     struct sockaddr_in sin;
 454     memset(&sin, 0, sizeof(sin));
 455     sin.sin_family = AF_INET;
 456     sin.sin_addr = io->io.bind;
 457     sin.sin_port = 0;
 458     if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)))
 459       goto fail_1;
 460   }
 461   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 462   return (conn_init(c, sel, fd, (struct sockaddr *)&ia->sin, sizeof(ia->sin),
 463                     starget_connected, e));
 464 fail_1:
 465   close(fd);
 466 fail_0:
 467   return (-1);
 468 }
 469
 470 /* --- Ops table --- */
 471
 472 addr_ops inet_ops = {
 473   "inet",
 474   inet_read, inet_destroy, inet_print,
 475   inet_initsrcopts, inet_option, inet_confirm, inet_freesrcopts,
 476   inet_bind, 0, inet_accept,
 477   inet_inittargopts, inet_freetargopts,
 478   inet_connect
 479 };
 480
 481 /*----- That's all, folks -------------------------------------------------*/