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

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