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

   1 /* -*-c-*-
   2  *
   3  * $Id: inet.c,v 1.4 2002/01/13 14:49:56 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 1.4  2002/01/13 14:49:56  mdw
  33  * Conditional compilation for @getnetbyname@, since Cygwin doesn't have
  34  * it.
  35  *
  36  * Revision 1.3  2000/08/01 17:59:56  mdw
  37  * Switch over to using `size_t' for socket address lengths.
  38  *
  39  * Revision 1.2  1999/07/27 18:30:53  mdw
  40  * Various minor portability fixes.
  41  *
  42  * Revision 1.1  1999/07/26 23:34:11  mdw
  43  * New socket address types.
  44  *
  45  */
  46
  47 /*----- Header files ------------------------------------------------------*/
  48
  49 #include "config.h"
  50
  51 #include <ctype.h>
  52 #include <errno.h>
  53 #include <stdio.h>
  54 #include <stdlib.h>
  55 #include <string.h>
  56
  57 #include <sys/types.h>
  58 #include <unistd.h>
  59
  60 #include <sys/socket.h>
  61 #include <netinet/in.h>
  62 #include <arpa/inet.h>
  63 #include <netdb.h>
  64
  65 #include <mLib/alloc.h>
  66 #include <mLib/dstr.h>
  67 #include <mLib/report.h>
  68 #include <mLib/sub.h>
  69
  70 #include "acl.h"
  71 #include "addr.h"
  72 #include "conf.h"
  73 #include "identify.h"
  74 #include "inet.h"
  75 #include "reffd.h"
  76 #include "scan.h"
  77
  78 /*----- Data structures ---------------------------------------------------*/
  79
  80 typedef struct inet_addrx {
  81   addr a;
  82   struct sockaddr_in sin;
  83 } inet_addrx;
  84
  85 typedef struct inet_opts {
  86   addr_opts ao;
  87   acl_entry *acl;
  88   acl_entry **acltail;
  89 } inet_opts;
  90
  91 /*----- Protocol operations -----------------------------------------------*/
  92
  93 /* --- @read@ --- */
  94
  95 static addr *inet_read(scanner *sc, unsigned type)
  96 {
  97   inet_addrx *ia = xmalloc(sizeof(*ia));
  98
  99   ia->a.ops = &inet_ops;
 100   ia->a.sz = sizeof(struct sockaddr_in);
 101   memset(&ia->sin, 0, sizeof(ia->sin));
 102   ia->sin.sin_family = AF_INET;
 103
 104   /* --- Read the host address part --- */
 105
 106   switch (type) {
 107     case ADDR_SRC:
 108       if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "port") == 0)
 109         token(sc);
 110       ia->sin.sin_addr.s_addr = htonl(INADDR_ANY);
 111       break;
 112     case ADDR_DEST: {
 113       struct hostent *h;
 114       dstr d = DSTR_INIT;
 115       conf_name(sc, '.', &d);
 116       if ((h = gethostbyname(d.buf)) == 0)
 117         error(sc, "couldn't resolve Internet address `%s'", d.buf);
 118       memcpy(&ia->sin.sin_addr, h->h_addr, sizeof(struct in_addr));
 119       dstr_destroy(&d);
 120       if (sc->t == ':')
 121         token(sc);
 122     } break;
 123   }
 124
 125   /* --- Read the port number --- */
 126
 127   {
 128     struct servent *s;
 129
 130     if (sc->t != CTOK_WORD)
 131       error(sc, "parse error, TCP port expected");
 132     if (isdigit((unsigned char)sc->d.buf[0]))
 133       ia->sin.sin_port = htons(atoi(sc->d.buf));
 134     else if ((s = getservbyname(sc->d.buf, "tcp")) == 0)
 135       error(sc, "unknown tcp service `%s'", sc->d.buf);
 136     else
 137       ia->sin.sin_port = s->s_port;
 138     token(sc);
 139   }
 140
 141   return (&ia->a);
 142 }
 143
 144 /* --- @destroy@ --- */
 145
 146 static void inet_destroy(addr *a)
 147 {
 148   inet_addrx *ia = (inet_addrx *)a;
 149   DESTROY(ia);
 150 }
 151
 152 /* --- @print@ --- */
 153
 154 static void inet_print(addr *a, unsigned type, dstr *d)
 155 {
 156   inet_addrx *ia = (inet_addrx *)a;
 157   switch (type) {
 158     case ADDR_SRC:
 159       dstr_putf(d, "inet:%u", (unsigned)ntohs(ia->sin.sin_port));
 160       break;
 161     case ADDR_DEST:
 162       dstr_putf(d, "inet:%s:%u",
 163                 inet_ntoa(ia->sin.sin_addr),
 164                 (unsigned)ntohs(ia->sin.sin_port));
 165       break;
 166   }
 167 }
 168
 169 /* --- @initopts@ --- */
 170
 171 static addr_opts *inet_initopts(void)
 172 {
 173   inet_opts *io = CREATE(inet_opts);
 174   io->acl = 0;
 175   io->acltail = &io->acl;
 176   return (&io->ao);
 177 }
 178
 179 /* --- @option@ --- */
 180
 181 static int inet_option(scanner *sc, addr_opts *ao)
 182 {
 183   inet_opts *io = (inet_opts *)ao;
 184
 185   CONF_BEGIN(sc, "inet", "Internet socket")
 186
 187   unsigned act;
 188
 189   /* --- Access control limitations --- */
 190
 191   if ((strcmp(sc->d.buf, "allow") == 0 && (act = ACL_ALLOW, 1)) ||
 192        (strcmp(sc->d.buf, "deny") == 0 && (act = ACL_DENY, 1))) {
 193     struct hostent *h;
 194     struct netent *n;
 195     struct in_addr a, m;
 196     dstr d = DSTR_INIT;
 197
 198     /* --- Find the host or network address --- */
 199
 200     token(sc);
 201     if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "from") == 0)
 202       token(sc);
 203     conf_name(sc, '.', &d);
 204 #ifdef HAVE_GETNETBYNAME
 205     if ((n = getnetbyname(d.buf)) != 0)
 206       a.s_addr = htonl(n->n_net);
 207     else
 208 #endif
 209     if ((h = gethostbyname(d.buf)) == 0)
 210       error(sc, "couldn't resolve address `%s'", d.buf);
 211     else
 212       memcpy(&a, h->h_addr, sizeof(struct in_addr));
 213
 214     /* --- Find the netmask, if any --- */
 215
 216     if (sc->t != '/')
 217       m.s_addr = ~0ul;
 218     else {
 219       token(sc);
 220       DRESET(&d);
 221       conf_name(sc, '.', &d);
 222       if (strchr(d.buf, '.') == 0) {
 223         int n = atoi(d.buf);
 224         if (n == 0)
 225           m.s_addr = 0;
 226         else
 227           m.s_addr = htonl((~0ul << (32 - n)) & 0xffffffff);
 228       } else {
 229 #ifdef HAVE_INET_ATON
 230         if (!inet_aton(d.buf, &m))
 231           error(sc, "bad netmask `%s'", d.buf);
 232 #else
 233         m.s_addr = inet_addr(d.buf);
 234 #endif
 235       }
 236     }
 237     dstr_destroy(&d);
 238
 239     /* --- Add the access control entry --- */
 240
 241     acl_add(io ? &io->acltail : 0, act, a, m);
 242     CONF_ACCEPT;
 243   }
 244
 245   /* --- Anything unrecognized --- */
 246
 247   CONF_END;
 248 }
 249
 250 /* --- @accept@ --- */
 251
 252 static reffd *inet_accept(int fd, addr_opts *ao, const char *desc)
 253 {
 254   inet_opts *io = (inet_opts *)ao;
 255   int nfd;
 256   id_req q;
 257   size_t lsinsz = sizeof(q.lsin), rsinsz = sizeof(q.rsin);
 258
 259   /* --- Accept the new connection --- */
 260
 261   if ((nfd = accept(fd, (struct sockaddr *)&q.rsin, &rsinsz)) < 0)
 262     return (0);
 263   if (getsockname(nfd, (struct sockaddr *)&q.lsin, &lsinsz)) {
 264     close(nfd);
 265     return (0);
 266   }
 267   q.desc = desc;
 268   q.r = reffd_init(nfd);
 269
 270   /* --- Find out whether this connection is allowed --- */
 271
 272   if (!acl_check(io->acl, q.rsin.sin_addr)) {
 273     q.act = "refused";
 274     if (!(io->ao.f & ADDRF_NOLOG))
 275       identify(&q);
 276     REFFD_DEC(q.r);
 277     return (0);
 278   }
 279
 280   /* --- Everything seems to be OK --- */
 281
 282   q.act = "accepted";
 283   if (!(io->ao.f & ADDRF_NOLOG))
 284     identify(&q);
 285   return (q.r);
 286 }
 287
 288 /* --- @freeopts@ --- */
 289
 290 static void inet_freeopts(addr_opts *ao)
 291 {
 292   inet_opts *io = (inet_opts *)ao;
 293   acl_free(io->acl);
 294   DESTROY(ao);
 295 }
 296
 297 /* --- Ops table --- */
 298
 299 addr_ops inet_ops = {
 300   "inet", PF_INET,
 301   inet_read, inet_destroy, inet_print,
 302   inet_initopts, inet_option, inet_accept, inet_freeopts, 0, 0
 303 };
 304
 305 /*----- That's all, folks -------------------------------------------------*/