Fix data corruption in channel\!

[fwd] / inet.c

/* -*-c-*-
 *
 * $Id: inet.c,v 1.4 2002/01/13 14:49:56 mdw Exp $
 *
 * Protocol specific definitions for IPv4 sockets
 *
 * (c) 1999 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of the `fw' port forwarder.
 *
 * `fw' is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * `fw' is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with `fw'; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: inet.c,v $
 * Revision 1.4  2002/01/13 14:49:56  mdw
 * Conditional compilation for @getnetbyname@, since Cygwin doesn't have
 * it.
 *
 * Revision 1.3  2000/08/01 17:59:56  mdw
 * Switch over to using `size_t' for socket address lengths.
 *
 * Revision 1.2  1999/07/27 18:30:53  mdw
 * Various minor portability fixes.
 *
 * Revision 1.1  1999/07/26 23:34:11  mdw
 * New socket address types.
 *
 */

/*----- Header files ------------------------------------------------------*/

#include "config.h"

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <unistd.h>

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#include <mLib/alloc.h>
#include <mLib/dstr.h>
#include <mLib/report.h>
#include <mLib/sub.h>

#include "acl.h"
#include "addr.h"
#include "conf.h"
#include "identify.h"
#include "inet.h"
#include "reffd.h"
#include "scan.h"

/*----- Data structures ---------------------------------------------------*/

typedef struct inet_addrx {
  addr a;
  struct sockaddr_in sin;
} inet_addrx;

typedef struct inet_opts {
  addr_opts ao;
  acl_entry *acl;
  acl_entry **acltail;
} inet_opts;

/*----- Protocol operations -----------------------------------------------*/

/* --- @read@ --- */

static addr *inet_read(scanner *sc, unsigned type)
{
  inet_addrx *ia = xmalloc(sizeof(*ia));

  ia->a.ops = &inet_ops;
  ia->a.sz = sizeof(struct sockaddr_in);
  memset(&ia->sin, 0, sizeof(ia->sin));
  ia->sin.sin_family = AF_INET;

  /* --- Read the host address part --- */

  switch (type) {
    case ADDR_SRC:
      if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "port") == 0)
	token(sc);
      ia->sin.sin_addr.s_addr = htonl(INADDR_ANY);
      break;
    case ADDR_DEST: {
      struct hostent *h;
      dstr d = DSTR_INIT;
      conf_name(sc, '.', &d);
      if ((h = gethostbyname(d.buf)) == 0)
	error(sc, "couldn't resolve Internet address `%s'", d.buf);
      memcpy(&ia->sin.sin_addr, h->h_addr, sizeof(struct in_addr));
      dstr_destroy(&d);
      if (sc->t == ':')
	token(sc);
    } break;
  }

  /* --- Read the port number --- */

  {
    struct servent *s;

    if (sc->t != CTOK_WORD)
      error(sc, "parse error, TCP port expected");
    if (isdigit((unsigned char)sc->d.buf[0]))
      ia->sin.sin_port = htons(atoi(sc->d.buf));
    else if ((s = getservbyname(sc->d.buf, "tcp")) == 0)
      error(sc, "unknown tcp service `%s'", sc->d.buf);
    else
      ia->sin.sin_port = s->s_port;
    token(sc);
  }

  return (&ia->a);
}

/* --- @destroy@ --- */

static void inet_destroy(addr *a)
{
  inet_addrx *ia = (inet_addrx *)a;
  DESTROY(ia);
}

/* --- @print@ --- */

static void inet_print(addr *a, unsigned type, dstr *d)
{
  inet_addrx *ia = (inet_addrx *)a;
  switch (type) {
    case ADDR_SRC:
      dstr_putf(d, "inet:%u", (unsigned)ntohs(ia->sin.sin_port));
      break;
    case ADDR_DEST:
      dstr_putf(d, "inet:%s:%u",
		inet_ntoa(ia->sin.sin_addr),
		(unsigned)ntohs(ia->sin.sin_port));
      break;
  }
}

/* --- @initopts@ --- */

static addr_opts *inet_initopts(void)
{
  inet_opts *io = CREATE(inet_opts);
  io->acl = 0;
  io->acltail = &io->acl;
  return (&io->ao);
}

/* --- @option@ --- */

static int inet_option(scanner *sc, addr_opts *ao)
{
  inet_opts *io = (inet_opts *)ao;

  CONF_BEGIN(sc, "inet", "Internet socket")

  unsigned act;

  /* --- Access control limitations --- */

  if ((strcmp(sc->d.buf, "allow") == 0 && (act = ACL_ALLOW, 1)) ||
       (strcmp(sc->d.buf, "deny") == 0 && (act = ACL_DENY, 1))) {
    struct hostent *h;
    struct netent *n;
    struct in_addr a, m;
    dstr d = DSTR_INIT;

    /* --- Find the host or network address --- */

    token(sc);
    if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "from") == 0)
      token(sc);
    conf_name(sc, '.', &d);
#ifdef HAVE_GETNETBYNAME
    if ((n = getnetbyname(d.buf)) != 0)
      a.s_addr = htonl(n->n_net);
    else
#endif
    if ((h = gethostbyname(d.buf)) == 0)
      error(sc, "couldn't resolve address `%s'", d.buf);
    else
      memcpy(&a, h->h_addr, sizeof(struct in_addr));

    /* --- Find the netmask, if any --- */

    if (sc->t != '/')
      m.s_addr = ~0ul;
    else {
      token(sc);
      DRESET(&d);
      conf_name(sc, '.', &d);
      if (strchr(d.buf, '.') == 0) {
	int n = atoi(d.buf);
	if (n == 0)
	  m.s_addr = 0;
	else
	  m.s_addr = htonl((~0ul << (32 - n)) & 0xffffffff);
      } else {
#ifdef HAVE_INET_ATON
	if (!inet_aton(d.buf, &m))
	  error(sc, "bad netmask `%s'", d.buf);
#else
	m.s_addr = inet_addr(d.buf);
#endif
      }
    }
    dstr_destroy(&d);

    /* --- Add the access control entry --- */

    acl_add(io ? &io->acltail : 0, act, a, m);
    CONF_ACCEPT;
  }

  /* --- Anything unrecognized --- */

  CONF_END;
}

/* --- @accept@ --- */

static reffd *inet_accept(int fd, addr_opts *ao, const char *desc)
{
  inet_opts *io = (inet_opts *)ao;
  int nfd;
  id_req q;
  size_t lsinsz = sizeof(q.lsin), rsinsz = sizeof(q.rsin);

  /* --- Accept the new connection --- */

  if ((nfd = accept(fd, (struct sockaddr *)&q.rsin, &rsinsz)) < 0)
    return (0);
  if (getsockname(nfd, (struct sockaddr *)&q.lsin, &lsinsz)) {
    close(nfd);
    return (0);
  }
  q.desc = desc;
  q.r = reffd_init(nfd);

  /* --- Find out whether this connection is allowed --- */

  if (!acl_check(io->acl, q.rsin.sin_addr)) {
    q.act = "refused";
    if (!(io->ao.f & ADDRF_NOLOG))
      identify(&q);
    REFFD_DEC(q.r);
    return (0);
  }

  /* --- Everything seems to be OK --- */

  q.act = "accepted";
  if (!(io->ao.f & ADDRF_NOLOG))
    identify(&q);
  return (q.r);
}

/* --- @freeopts@ --- */

static void inet_freeopts(addr_opts *ao)
{
  inet_opts *io = (inet_opts *)ao;
  acl_free(io->acl);
  DESTROY(ao);
}

/* --- Ops table --- */

addr_ops inet_ops = {
  "inet", PF_INET,
  inet_read, inet_destroy, inet_print,
  inet_initopts, inet_option, inet_accept, inet_freeopts, 0, 0
};

/*----- That's all, folks -------------------------------------------------*/