And a typo fix.

[fwd] / inet.c

/* -*-c-*-
 *
 * $Id: inet.c,v 1.6 2003/11/29 20:36:07 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 1.6  2003/11/29 20:36:07  mdw
 * Privileged outgoing connections.
 *
 * Revision 1.5  2003/11/25 14:08:23  mdw
 * Debianization.  Socket target options.  Internet binding.
 *
 * 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/fdflags.h>
#include <mLib/report.h>
#include <mLib/sub.h>

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

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

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

typedef struct inet_opts {
  addr_opts ao;
  struct in_addr bind;
} inet_opts;

typedef struct inet_srcopts {
  inet_opts io;
  acl_entry *acl;
  acl_entry **acltail;
} inet_srcopts;

typedef struct inet_targopts {
  inet_opts io;
  int ipriv;
} inet_targopts;

#define ADDRF_PRIVCONN 16u

static inet_srcopts inet_globalsrc =
  { { { 0 }, { INADDR_ANY } }, 0, &inet_globalsrc.acl };
static inet_targopts inet_globaltarg =
  { { { 0 }, { INADDR_ANY } } };

/*----- 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_initsrcopts(void)
{
  inet_srcopts *io = CREATE(inet_srcopts);
  *io = inet_globalsrc;
  io->acl = 0;
  io->acltail = &io->acl;
  return (&io->io.ao);
}

static addr_opts *inet_inittargopts(void)
{
  inet_targopts *io = CREATE(inet_targopts);
  *io = inet_globaltarg;
  io->ipriv = -1;
  return (&io->io.ao);
}

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

static void addropt(scanner *sc, inet_opts *io)
{
  dstr d = DSTR_INIT;
  struct hostent *h;

  token(sc);
  if (sc->t == '=')
    token(sc);
  if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "any") == 0)
    io->bind.s_addr = INADDR_ANY;
  else {
    conf_name(sc, '.', &d);
    if ((h = gethostbyname(d.buf)) == 0)
      error(sc, "couldn't resolve address `%s'", d.buf);
    memcpy(&io->bind, h->h_addr, sizeof(struct in_addr));
  }
}

static int srcopt(scanner *sc, addr_opts *ao)
{
  inet_srcopts *io = (inet_srcopts *)ao;
  unsigned act;

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

  /* --- Initialization --- */

  if (!io) {
    if (!inet_globalsrc.acltail)
      inet_globalsrc.acltail = &inet_globalsrc.acl;
    io = &inet_globalsrc;
  }

  /* --- Source address configuration --- */

  if (strcmp(sc->d.buf, "addr") == 0) {
    addropt(sc, &io->io);
    CONF_ACCEPT;
  }

  /* --- 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 out what's going on --- */

    token(sc);
    if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "from") == 0)
      token(sc);

    if (sc->t == CTOK_WORD && (strcmp(sc->d.buf, "priv") == 0 ||
			       strcmp(sc->d.buf, "priv-port") == 0)) {
      acl_addpriv(&io->acltail, act);
      token(sc);
    } else {
      if (sc->t == CTOK_WORD && strcmp(sc->d.buf, "host") == 0)
	token(sc);

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

      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_addhost(&io->acltail, act, a, m);
    }
    CONF_ACCEPT;
  }

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

  CONF_END;
}

static int targopt(scanner *sc, addr_opts *ao)
{
  inet_targopts *io = (inet_targopts *)ao;

  CONF_BEGIN(sc, "dest", "Internet socket target");
  if (strcmp(sc->d.buf, "addr") == 0) {
    addropt(sc, &io->io);
    CONF_ACCEPT;
  }
  if (strcmp(sc->d.buf, "priv") == 0 ||
      strcmp(sc->d.buf, "priv-port") == 0) {
    token(sc);
    if (sc->t == '=') token(sc);
    if (conf_enum(sc, "no,yes", ENUM_ABBREV, "privileged connection status"))
      io->io.ao.f |= ADDRF_PRIVCONN;
    else
      io->io.ao.f &= ~ADDRF_PRIVCONN;
    CONF_ACCEPT;
  }
  CONF_END;
}

static int inet_option(scanner *sc, addr_opts *ao, unsigned type)
{
  CONF_BEGIN(sc, "inet", "Internet socket");
  if (type != ADDR_DEST && srcopt(sc, ao))
    CONF_ACCEPT;
  if (type != ADDR_SRC && targopt(sc, ao))
    CONF_ACCEPT;
  CONF_END;
}

/* --- @confirm@ --- */

static void inet_confirm(addr *a, unsigned type, addr_opts *ao)
{
  inet_addrx *ia = (inet_addrx *)a;

  switch (type) {
    case ADDR_DEST: {
      inet_targopts *io = (inet_targopts *)ao;
      if ((io->io.ao.f & ADDRF_PRIVCONN) &&
	  (io->ipriv = privconn_adddest(ia->sin.sin_addr,
					ia->sin.sin_port)) < 0)
	die(1, "couldn't add privileged connection target (too late)");
    } break;
  }
}

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

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

static void inet_freetargopts(addr_opts *ao)
{
  inet_targopts *io = (inet_targopts *)ao;
  DESTROY(io);
}

/* --- @bind@ --- */

static int inet_bind(addr *a, addr_opts *ao)
{
  inet_addrx *ia = (inet_addrx *)a;
  inet_srcopts *io = (inet_srcopts *)ao;
  struct sockaddr_in sin;
  int opt = 1;
  int fd;

  if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
    goto fail_0;
  setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
  fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
  sin = ia->sin;
  sin.sin_addr = io->io.bind;
  if (bind(fd, (struct sockaddr *)&sin, sizeof(ia->sin)))
    goto fail_1;
  return (fd);

fail_1:
  close(fd);
fail_0:
  return (-1);
}

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

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

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

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

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

/* --- @connect@ --- */

static int inet_connect(addr *a, addr_opts *ao, conn *c, endpt *e)
{
  inet_addrx *ia = (inet_addrx *)a;
  inet_targopts *io = (inet_targopts *)ao;
  int fd;

  if (io->ipriv >= 0) {
    return (privconn_connect(c, sel, io->ipriv, io->io.bind,
			     starget_connected, e));
  }
  if ((fd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
    goto fail_0;
  if (io->io.bind.s_addr != INADDR_ANY) {
    struct sockaddr_in sin;
    memset(&sin, 0, sizeof(sin));
    sin.sin_family = AF_INET;
    sin.sin_addr = io->io.bind;
    sin.sin_port = 0;
    if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)))
      goto fail_1;
  }
  fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
  return (conn_init(c, sel, fd, (struct sockaddr *)&ia->sin, sizeof(ia->sin),
		    starget_connected, e));
fail_1:
  close(fd);
fail_0:
  return (-1);
}

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

addr_ops inet_ops = {
  "inet",
  inet_read, inet_destroy, inet_print,
  inet_initsrcopts, inet_option, inet_confirm, inet_freesrcopts,
  inet_bind, 0, inet_accept,
  inet_inittargopts, inet_freetargopts,
  inet_connect  
};

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