[tripe] / tun-slip.c

/* -*-c-*-
 *
 * $Id$
 *
 * Tunnel packets via SLIP
 *
 * (c) 2005 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Trivial IP Encryption (TrIPE).
 *
 * TrIPE 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.
 * 
 * TrIPE 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 TrIPE; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

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

#define TUN_INTERNALS

#include "tripe.h"

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

typedef struct slipif {
  struct slipif *next;			/* Next one in the list */
  int ifd, ofd;				/* File descriptors to talk on */
  char *name;				/* Interface name */
  pid_t kid;				/* Child process id */
  unsigned f;				/* Various flags */
#   define F_INUSE 1u			/*   Interface is in use */
#   define F_DYNAMIC 2u			/*   Interface found dynamically */
} slipif;

struct tunnel {
  const tunnel_ops *ops;		/* Pointer to operations */
  slipif *sl;				/* My interface record */
  sel_file f;				/* Selector for SLIP tty */
  struct peer *p;			/* Pointer to my peer */
  unsigned st;				/* Current parser state */
#   define ST_ESC 1u			/*   Last saw an escape character */
#   define ST_BAD 2u			/*   This packet is malformed */
#   define ST_EOF 4u			/*   File descriptor reported EOF */
  size_t n;				/* Number of bytes used in buffer */
  octet buf[PKBUFSZ];			/* Buffer for incoming data */
};  

/*----- Static variables --------------------------------------------------*/

static slipif *slipifs;			/* List of available interfaces */
static const char *slipcmd;		/* Script to make new interfaces */

/*----- Main code ---------------------------------------------------------*/

#define SL_END 0xc0
#define SL_ESC 0xdb
#define SL_ESCEND 0xdc
#define SL_ESCESC 0xdd

/* --- @t_read@ --- *
 *
 * Arguments:	@int fd@ = file descriptor to read
 *		@unsigned mode@ = what's happened
 *		@void *v@ = pointer to tunnel block
 *
 * Returns:	---
 *
 * Use:		Reads data from the tunnel.
 */

static void t_read(int fd, unsigned mode, void *v)
{
  tunnel *t = v;
  ssize_t n;
  const octet *p, *l, *ll;
  octet *q;
  unsigned st;
  octet o;
  buf b;

  /* --- Read the input data --- */

  n = read(fd, buf_t, sizeof(buf_t));
  if (n < 0) {
    if (errno == EINTR ||
#if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
	errno == EWOULDBLOCK ||
#endif
	errno == EAGAIN)
      return;
    a_warn("TUN %s read-error -- %s", t->sl->name, strerror(errno));
    return;
  }
  if (!n) {
    a_warn("TUN %s slip eof", t->sl->name);
    t->st = ST_EOF;
    sel_rmfile(&t->f);
    return;
  }
  IF_TRACING(T_TUNNEL, {
    trace_block(T_PACKET, "tun-slip: SLIP-encapsulated data",
		buf_t, n);
  })

  /* --- Decapsulate the packet --- */

  for (p = buf_t, l = p + n, st = t->st,
       q = t->buf + t->n, ll = t->buf + sizeof(t->buf);
       p < l;
       p++) {
    o = *p;
    switch (o) {
      case SL_END:
	if (st & ST_BAD)
	  ;
	else if (st & ST_ESC)
	  a_warn("TUN %s slip escape-end", t->sl->name);
	else if (q == t->buf) {
	  T( trace(T_TUNNEL, "tun-slip: empty packet"); )
	} else {
	  IF_TRACING(T_TUNNEL, {
	    trace(T_TUNNEL, "tun-slip: packet arrived");
	    trace_block(T_PACKET, "tun-slip: packet contents",
			t->buf, q - t->buf);
	  })
	  buf_init(&b, t->buf, q - t->buf);
	  p_tun(t->p, &b);
	}
	q = t->buf;
	st &= ~(ST_ESC | ST_BAD);
	break;
      case SL_ESC:
	if ((st & ST_ESC) && !(st & ST_BAD)) {
	  a_warn("TUN %s slip bad-escape", t->sl->name);
	  st |= ST_BAD;
	} else
	  st |= ST_ESC;
	break;
      case SL_ESCEND:
	if (st & ST_ESC)
	  o = SL_END;
	goto emit;
      case SL_ESCESC:
	if (st & ST_ESC)
	  o = SL_ESC;
	goto emit;
      default:
	if ((st & ST_ESC) && !(st & ST_BAD)) {
	  a_warn("TUN %s slip bad-escape", t->sl->name);
	  st |= ST_BAD;
	}
      emit:
	if (!(st & ST_BAD)) {
	  if (q < ll)
	    *q++ = o;
	  else {
	    a_warn("TUN %s slip overflow", t->sl->name);
	    st |= ST_BAD;
	  }
	}
	st &= ~ST_ESC;
	break;
    }
  }

  t->n = q - t->buf;
  t->st = st;
}

/* --- @t_init@ --- *
 *
 * Arguments:	---
 *
 * Returns:	---
 *
 * Use:		Initializes the tunneling system.  Maybe this will require
 *		opening file descriptors or something.
 */

static void t_init(void)
{
  char *p, *q;
  dstr d = DSTR_INIT;
  slipif *sl, **tail = &slipifs;
  unsigned long uli, ulo;
  size_t n;

  if ((p = getenv("TRIPE_SLIPIF")) == 0)
    return;

  /* --- Build the list of available interfaces --- */

  dstr_puts(&d, p);

  p = d.buf;
  for (;;) {
    if (*p == '/' || *p == '.') {
      slipcmd = p;
      T( trace(T_TUNNEL, "tun-slip: declared slip command `%s'", slipcmd); )
      break;
    }
    uli = strtoul(p, &q, 0);
    if (uli > INT_MAX || q == p)
      goto whine;
    if (*q != ',')
      ulo = uli;
    else {
      p = q + 1;
      ulo = strtoul(p, &q, 0);
      if (ulo > INT_MAX || q == p)
	goto whine;
    }
    if (*q != '=' || (n = strcspn(q + 1, ":")) == 0)
      goto whine;
    sl = CREATE(slipif);
    sl->next = 0;
    sl->ifd = uli;
    fdflags(sl->ifd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
    fdflags(sl->ofd, O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC);
    sl->ofd = ulo;
    sl->name = xmalloc(n + 1);
    sl->kid = -1;
    sl->f = 0;
    memcpy(sl->name, q + 1, n);
    sl->name[n] = 0;
    *tail = sl;
    tail = &sl->next;
    T( trace(T_TUNNEL, "tun-slip: declared slipif %d,%d=%s",
	     sl->ifd, sl->ofd, sl->name); )
    p = q + n + 1;
    if (!*p)
      break;
    p++;
  }
  return;

whine:
  moan("bad slip interface list");
}

/* --- @t_create@ --- *
 *
 * Arguments:	@peer *p@ = pointer to peer block
 *
 * Returns:	A tunnel block if it worked, or null on failure.
 *
 * Use:		Initializes a new tunnel.
 */

static tunnel *t_create(peer *p)
{
  slipif *sl = 0;
  int pin[2] = { -1, -1 }, pout[2] = { -1, -1 };
  pid_t kid = -1;
  dstr d = DSTR_INIT;
  unsigned char ch;
  tunnel *t;
  static const char end[] = { SL_END, SL_END };

  /* --- Try to find a spare static interface --- */

  for (sl = slipifs; sl; sl = sl->next) {
    if (!(sl->f & F_INUSE)) {
      T( trace(T_TUNNEL, "tun-slip: %s using static slipif %s",
	       p_name(p), sl->name); )
      goto found;
    }
  }

  /* --- If no dynamic interfaces are available, give up --- */

  if (!slipcmd) {
    a_warn("TUN - slip no-slip-interfaces");
    goto fail;
  }

  /* --- Fork off a child process to create a dynamic SLIP interface --- */

  if (pipe(pin) || pipe(pout)) {
    a_warn("TUN - slip pipe-error -- %s", strerror(errno));
    goto fail;
  }
  if ((kid = fork()) < 0) {
    a_warn("TUN - slip fork-error -- %s", strerror(errno));
    goto fail;
  }
  if (!kid) {
    close(pin[1]);
    close(pout[0]);
    dup2(pin[0], STDIN_FILENO);
    dup2(pout[1], STDOUT_FILENO);
    execlp(slipcmd, slipcmd, p_name(p), (char *)0);
    _exit(127);
  }

  /* --- Read the interface name --- */

  sl = CREATE(slipif);
  close(pin[0]); pin[0] = -1;
  close(pout[1]); pout[1] = -1;
  for (;;) {
    errno = EIO;
    if (read(pout[0], &ch, 1) != 1 || ch == SL_END) {
      a_warn("TUN - slip read-ifname-failed -- %s", strerror(errno));
      goto fail;
    }
    if (ch == '\n')
      break;
    DPUTC(&d, (char)ch);
  }
  DPUTZ(&d);
  sl->name = xstrdup(d.buf);
  sl->ifd = pout[0];
  sl->ofd = pin[1];
  sl->kid = kid;
  sl->next = 0;
  sl->f = F_DYNAMIC;
  T( trace(T_TUNNEL, "tun-slip: %s using dynamic slipif %s",
	   p_name(p), sl->name); )
  fdflags(pout[0], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
  fdflags(pin[1], O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC);

  /* --- Set up the new tunnel --- */

found:
  t = CREATE(tunnel);
  t->ops = &tun_slip;
  t->p = p;
  t->sl = sl;
  t->st = 0;
  t->n = 0;
  sl->f |= F_INUSE;
  sel_initfile(&sel, &t->f, sl->ifd, SEL_READ, t_read, t);
  sel_addfile(&t->f);
  write(sl->ofd, end, sizeof(end));
  dstr_destroy(&d);
  return (t);

  /* --- Tidy up after a failure --- */

fail:
#define CLOSE(fd) do if (fd != -1) close(fd); while (0)
  CLOSE(pin[0]); CLOSE(pout[0]);
  CLOSE(pin[1]); CLOSE(pout[1]);
#undef CLOSE
  if (kid != -1) kill(kid, SIGTERM);
  if (sl && (sl->f & F_DYNAMIC)) DESTROY(sl);
  dstr_destroy(&d);
  return (0);
}

/* --- @t_ifname@ --- *
 *
 * Arguments:	@tunnel *t@ = pointer to tunnel block
 *
 * Returns:	A pointer to the tunnel's interface name.
 */

static const char *t_ifname(tunnel *t) { return (t->sl->name); }

/* --- @t_inject@ --- *
 *
 * Arguments:	@tunnel *t@ = pointer to tunnel block
 *		@buf *b@ = buffer to send
 *
 * Returns:	---
 *
 * Use:		Injects a packet into the local network stack.
 */

static void t_inject(tunnel *t, buf *b)
{
  octet buf[PKBUFSZ * 2 + 2];
  const octet *p, *l;
  octet *q;

  IF_TRACING(T_TUNNEL, {
    trace(T_TUNNEL, "tun-slip: inject decrypted packet");
    trace_block(T_PACKET, "tun-slip: packet contents", BBASE(b), BLEN(b));
  })

  q = buf;
  *q++ = SL_END;
  for (p = BBASE(b), l = BCUR(b); p < l; p++) {
    switch (*p) {
      case SL_END: *q++ = SL_ESC; *q++ = SL_ESCEND; break;
      case SL_ESC: *q++ = SL_ESC; *q++ = SL_ESCESC; break;
      default: *q++ = *p; break;
    }
  }
  *q++ = SL_END;
  IF_TRACING(T_TUNNEL, {
    trace_block(T_PACKET, "tun-slip: SLIP-encapsulated contents",
		buf, q - buf);
  })
  write(t->sl->ofd, buf, q - buf);
}

/* --- @t_destroy@ --- *
 *
 * Arguments:	@tunnel *t@ = pointer to tunnel block
 *
 * Returns:	---
 *
 * Use:		Destroys a tunnel.
 */

static void t_destroy(tunnel *t)
{
  slipif *sl = t->sl;

  /* --- If it reported EOF, leave it out-of-action --- */

  if (!(t->st & ST_EOF)) {
    sel_rmfile(&t->f);
    sl->f &= ~F_INUSE;
  }
  if (sl && (sl->f & F_DYNAMIC)) {
    T( trace(T_TUNNEL, "tun-slip: releasing dynamic slipif %s", sl->name); )
    close(sl->ofd);
    close(sl->ifd);
    kill(sl->kid, SIGTERM);
    xfree(sl->name);
    DESTROY(sl);
  }
  DESTROY(t);
}

const tunnel_ops tun_slip = {
  "slip",
  t_init,
  t_create,
  t_ifname,
  t_inject,
  t_destroy
};

/*----- That's all, folks -------------------------------------------------*/
Commit	Line	Data
b9066fbb	1	/* --c--
	2	*
	3	* $Id$
	4	*
	5	* Tunnel packets via SLIP
	6	*
	7	* (c) 2005 Straylight/Edgeware
	8	*/
	9
	10	/----- Licensing notice --------------------------------------------------
	11	*
	12	* This file is part of Trivial IP Encryption (TrIPE).
	13	*
	14	* TrIPE 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	* TrIPE 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 TrIPE; 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
42da2a58	31	#define TUN_INTERNALS
42da2a58	32
b9066fbb	33	#include "tripe.h"
b9066fbb	34
42da2a58	35	/----- Data structures ---------------------------------------------------/
	36
	37	typedef struct slipif {
	38	struct slipif next; / Next one in the list */
	39	int ifd, ofd; /* File descriptors to talk on */
	40	char name; / Interface name */
	41	pid_t kid; /* Child process id */
	42	unsigned f; /* Various flags */
	43	# define F_INUSE 1u /* Interface is in use */
	44	# define F_DYNAMIC 2u /* Interface found dynamically */
	45	} slipif;
	46
	47	struct tunnel {
	48	const tunnel_ops ops; / Pointer to operations */
	49	slipif sl; / My interface record */
	50	sel_file f; /* Selector for SLIP tty */
	51	struct peer p; / Pointer to my peer */
	52	unsigned st; /* Current parser state */
	53	# define ST_ESC 1u /* Last saw an escape character */
	54	# define ST_BAD 2u /* This packet is malformed */
	55	# define ST_EOF 4u /* File descriptor reported EOF */
	56	size_t n; /* Number of bytes used in buffer */
	57	octet buf[PKBUFSZ]; /* Buffer for incoming data */
	58	};
	59
b9066fbb	60	/----- Static variables --------------------------------------------------/
	61
	62	static slipif slipifs; / List of available interfaces */
98fdb08d	63	static const char slipcmd; / Script to make new interfaces */
b9066fbb	64
	65	/----- Main code ---------------------------------------------------------/
	66
b9066fbb	67	#define SL_END 0xc0
	68	#define SL_ESC 0xdb
	69	#define SL_ESCEND 0xdc
	70	#define SL_ESCESC 0xdd
	71
	72	/* --- @t_read@ --- *
	73	*
	74	* Arguments: @int fd@ = file descriptor to read
	75	* @unsigned mode@ = what's happened
	76	* @void *v@ = pointer to tunnel block
	77	*
	78	* Returns: ---
	79	*
	80	* Use: Reads data from the tunnel.
	81	*/
	82
	83	static void t_read(int fd, unsigned mode, void *v)
	84	{
	85	tunnel *t = v;
	86	ssize_t n;
	87	const octet p, l, *ll;
	88	octet *q;
	89	unsigned st;
	90	octet o;
	91	buf b;
	92
	93	/* --- Read the input data --- */
	94
	95	n = read(fd, buf_t, sizeof(buf_t));
	96	if (n < 0) {
	97	if (errno == EINTR \|\|
98fdb08d	98	#if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
b9066fbb	99	errno == EWOULDBLOCK \|\|
	100	#endif
	101	errno == EAGAIN)
	102	return;
	103	a_warn("TUN %s read-error -- %s", t->sl->name, strerror(errno));
	104	return;
	105	}
	106	if (!n) {
	107	a_warn("TUN %s slip eof", t->sl->name);
42da2a58	108	t->st = ST_EOF;
b9066fbb	109	sel_rmfile(&t->f);
	110	return;
	111	}
	112	IF_TRACING(T_TUNNEL, {
060ca767	113	trace_block(T_PACKET, "tun-slip: SLIP-encapsulated data",
b9066fbb	114	buf_t, n);
	115	})
	116
	117	/* --- Decapsulate the packet --- */
	118
	119	for (p = buf_t, l = p + n, st = t->st,
	120	q = t->buf + t->n, ll = t->buf + sizeof(t->buf);
	121	p < l;
	122	p++) {
	123	o = *p;
	124	switch (o) {
	125	case SL_END:
42da2a58	126	if (st & ST_BAD)
b9066fbb	127	;
42da2a58	128	else if (st & ST_ESC)
b9066fbb	129	a_warn("TUN %s slip escape-end", t->sl->name);
b9066fbb	130	else if (q == t->buf) {
060ca767	131	T( trace(T_TUNNEL, "tun-slip: empty packet"); )
b9066fbb	132	} else {
b9066fbb	133	IF_TRACING(T_TUNNEL, {
060ca767	134	trace(T_TUNNEL, "tun-slip: packet arrived");
060ca767	135	trace_block(T_PACKET, "tun-slip: packet contents",
b9066fbb	136	t->buf, q - t->buf);
	137	})
	138	buf_init(&b, t->buf, q - t->buf);
	139	p_tun(t->p, &b);
	140	}
	141	q = t->buf;
42da2a58	142	st &= ~(ST_ESC \| ST_BAD);
b9066fbb	143	break;
b9066fbb	144	case SL_ESC:
42da2a58	145	if ((st & ST_ESC) && !(st & ST_BAD)) {
b9066fbb	146	a_warn("TUN %s slip bad-escape", t->sl->name);
42da2a58	147	st \|= ST_BAD;
b9066fbb	148	} else
42da2a58	149	st \|= ST_ESC;
b9066fbb	150	break;
b9066fbb	151	case SL_ESCEND:
42da2a58	152	if (st & ST_ESC)
b9066fbb	153	o = SL_END;
	154	goto emit;
	155	case SL_ESCESC:
42da2a58	156	if (st & ST_ESC)
b9066fbb	157	o = SL_ESC;
	158	goto emit;
	159	default:
42da2a58	160	if ((st & ST_ESC) && !(st & ST_BAD)) {
b9066fbb	161	a_warn("TUN %s slip bad-escape", t->sl->name);
42da2a58	162	st \|= ST_BAD;
b9066fbb	163	}
b9066fbb	164	emit:
42da2a58	165	if (!(st & ST_BAD)) {
b9066fbb	166	if (q < ll)
	167	*q++ = o;
	168	else {
	169	a_warn("TUN %s slip overflow", t->sl->name);
42da2a58	170	st \|= ST_BAD;
b9066fbb	171	}
b9066fbb	172	}
42da2a58	173	st &= ~ST_ESC;
b9066fbb	174	break;
	175	}
	176	}
	177
	178	t->n = q - t->buf;
	179	t->st = st;
	180	}
	181
42da2a58	182	/* --- @t_init@ --- *
b9066fbb	183	*
	184	* Arguments: ---
	185	*
	186	* Returns: ---
	187	*
	188	* Use: Initializes the tunneling system. Maybe this will require
	189	* opening file descriptors or something.
	190	*/
	191
42da2a58	192	static void t_init(void)
b9066fbb	193	{
	194	char p, q;
	195	dstr d = DSTR_INIT;
	196	slipif sl, *tail = &slipifs;
	197	unsigned long uli, ulo;
	198	size_t n;
	199
b9066fbb	200	if ((p = getenv("TRIPE_SLIPIF")) == 0)
42da2a58	201	return;
98fdb08d	202
	203	/* --- Build the list of available interfaces --- */
	204
b9066fbb	205	dstr_puts(&d, p);
	206
	207	p = d.buf;
	208	for (;;) {
98fdb08d	209	if (p == '/' \|\| p == '.') {
98fdb08d	210	slipcmd = p;
060ca767	211	T( trace(T_TUNNEL, "tun-slip: declared slip command `%s'", slipcmd); )
98fdb08d	212	break;
98fdb08d	213	}
b9066fbb	214	uli = strtoul(p, &q, 0);
	215	if (uli > INT_MAX \|\| q == p)
	216	goto whine;
	217	if (*q != ',')
	218	ulo = uli;
	219	else {
	220	p = q + 1;
	221	ulo = strtoul(p, &q, 0);
	222	if (ulo > INT_MAX \|\| q == p)
	223	goto whine;
	224	}
	225	if (*q != '=' \|\| (n = strcspn(q + 1, ":")) == 0)
	226	goto whine;
	227	sl = CREATE(slipif);
	228	sl->next = 0;
	229	sl->ifd = uli;
98fdb08d	230	fdflags(sl->ifd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
98fdb08d	231	fdflags(sl->ofd, O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC);
b9066fbb	232	sl->ofd = ulo;
b9066fbb	233	sl->name = xmalloc(n + 1);
98fdb08d	234	sl->kid = -1;
b9066fbb	235	sl->f = 0;
	236	memcpy(sl->name, q + 1, n);
	237	sl->name[n] = 0;
	238	*tail = sl;
	239	tail = &sl->next;
060ca767	240	T( trace(T_TUNNEL, "tun-slip: declared slipif %d,%d=%s",
b9066fbb	241	sl->ifd, sl->ofd, sl->name); )
	242	p = q + n + 1;
	243	if (!*p)
	244	break;
	245	p++;
	246	}
	247	return;
	248
	249	whine:
42da2a58	250	moan("bad slip interface list");
b9066fbb	251	}
b9066fbb	252
42da2a58	253	/* --- @t_create@ --- *
b9066fbb	254	*
42da2a58	255	* Arguments: @peer *p@ = pointer to peer block
b9066fbb	256	*
42da2a58	257	* Returns: A tunnel block if it worked, or null on failure.
b9066fbb	258	*
	259	* Use: Initializes a new tunnel.
	260	*/
	261
42da2a58	262	static tunnel t_create(peer p)
b9066fbb	263	{
98fdb08d	264	slipif *sl = 0;
	265	int pin[2] = { -1, -1 }, pout[2] = { -1, -1 };
	266	pid_t kid = -1;
	267	dstr d = DSTR_INIT;
	268	unsigned char ch;
42da2a58	269	tunnel *t;
b9066fbb	270	static const char end[] = { SL_END, SL_END };
b9066fbb	271
98fdb08d	272	/* --- Try to find a spare static interface --- */
98fdb08d	273
b9066fbb	274	for (sl = slipifs; sl; sl = sl->next) {
42da2a58	275	if (!(sl->f & F_INUSE)) {
060ca767	276	T( trace(T_TUNNEL, "tun-slip: %s using static slipif %s",
98fdb08d	277	p_name(p), sl->name); )
b9066fbb	278	goto found;
98fdb08d	279	}
b9066fbb	280	}
98fdb08d	281
	282	/* --- If no dynamic interfaces are available, give up --- */
	283
	284	if (!slipcmd) {
42da2a58	285	a_warn("TUN - slip no-slip-interfaces");
98fdb08d	286	goto fail;
	287	}
	288
	289	/* --- Fork off a child process to create a dynamic SLIP interface --- */
	290
	291	if (pipe(pin) \|\| pipe(pout)) {
42da2a58	292	a_warn("TUN - slip pipe-error -- %s", strerror(errno));
98fdb08d	293	goto fail;
	294	}
	295	if ((kid = fork()) < 0) {
42da2a58	296	a_warn("TUN - slip fork-error -- %s", strerror(errno));
98fdb08d	297	goto fail;
	298	}
	299	if (!kid) {
	300	close(pin[1]);
	301	close(pout[0]);
	302	dup2(pin[0], STDIN_FILENO);
	303	dup2(pout[1], STDOUT_FILENO);
	304	execlp(slipcmd, slipcmd, p_name(p), (char *)0);
	305	_exit(127);
	306	}
	307
	308	/* --- Read the interface name --- */
	309
	310	sl = CREATE(slipif);
	311	close(pin[0]); pin[0] = -1;
	312	close(pout[1]); pout[1] = -1;
	313	for (;;) {
	314	errno = EIO;
	315	if (read(pout[0], &ch, 1) != 1 \|\| ch == SL_END) {
42da2a58	316	a_warn("TUN - slip read-ifname-failed -- %s", strerror(errno));
98fdb08d	317	goto fail;
	318	}
	319	if (ch == '\n')
	320	break;
	321	DPUTC(&d, (char)ch);
	322	}
	323	DPUTZ(&d);
	324	sl->name = xstrdup(d.buf);
	325	sl->ifd = pout[0];
	326	sl->ofd = pin[1];
	327	sl->kid = kid;
	328	sl->next = 0;
42da2a58	329	sl->f = F_DYNAMIC;
060ca767	330	T( trace(T_TUNNEL, "tun-slip: %s using dynamic slipif %s",
98fdb08d	331	p_name(p), sl->name); )
	332	fdflags(pout[0], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
	333	fdflags(pin[1], O_NONBLOCK, 0, FD_CLOEXEC, FD_CLOEXEC);
	334
	335	/* --- Set up the new tunnel --- */
b9066fbb	336
b9066fbb	337	found:
42da2a58	338	t = CREATE(tunnel);
42da2a58	339	t->ops = &tun_slip;
b9066fbb	340	t->p = p;
	341	t->sl = sl;
	342	t->st = 0;
	343	t->n = 0;
42da2a58	344	sl->f \|= F_INUSE;
b9066fbb	345	sel_initfile(&sel, &t->f, sl->ifd, SEL_READ, t_read, t);
	346	sel_addfile(&t->f);
	347	write(sl->ofd, end, sizeof(end));
98fdb08d	348	dstr_destroy(&d);
42da2a58	349	return (t);
98fdb08d	350
	351	/* --- Tidy up after a failure --- */
	352
	353	fail:
	354	#define CLOSE(fd) do if (fd != -1) close(fd); while (0)
	355	CLOSE(pin[0]); CLOSE(pout[0]);
	356	CLOSE(pin[1]); CLOSE(pout[1]);
	357	#undef CLOSE
	358	if (kid != -1) kill(kid, SIGTERM);
42da2a58	359	if (sl && (sl->f & F_DYNAMIC)) DESTROY(sl);
98fdb08d	360	dstr_destroy(&d);
42da2a58	361	return (0);
b9066fbb	362	}
b9066fbb	363
42da2a58	364	/* --- @t_ifname@ --- *
b9066fbb	365	*
	366	* Arguments: @tunnel *t@ = pointer to tunnel block
	367	*
	368	* Returns: A pointer to the tunnel's interface name.
	369	*/
	370
42da2a58	371	static const char t_ifname(tunnel t) { return (t->sl->name); }
b9066fbb	372
42da2a58	373	/* --- @t_inject@ --- *
b9066fbb	374	*
	375	* Arguments: @tunnel *t@ = pointer to tunnel block
	376	* @buf *b@ = buffer to send
	377	*
	378	* Returns: ---
	379	*
	380	* Use: Injects a packet into the local network stack.
	381	*/
	382
42da2a58	383	static void t_inject(tunnel t, buf b)
b9066fbb	384	{
	385	octet buf[PKBUFSZ * 2 + 2];
	386	const octet p, l;
	387	octet *q;
	388
	389	IF_TRACING(T_TUNNEL, {
060ca767	390	trace(T_TUNNEL, "tun-slip: inject decrypted packet");
060ca767	391	trace_block(T_PACKET, "tun-slip: packet contents", BBASE(b), BLEN(b));
b9066fbb	392	})
	393
	394	q = buf;
	395	*q++ = SL_END;
	396	for (p = BBASE(b), l = BCUR(b); p < l; p++) {
	397	switch (*p) {
	398	case SL_END: q++ = SL_ESC; q++ = SL_ESCEND; break;
	399	case SL_ESC: q++ = SL_ESC; q++ = SL_ESCESC; break;
	400	default: q++ = p; break;
	401	}
	402	}
	403	*q++ = SL_END;
	404	IF_TRACING(T_TUNNEL, {
060ca767	405	trace_block(T_PACKET, "tun-slip: SLIP-encapsulated contents",
b9066fbb	406	buf, q - buf);
	407	})
	408	write(t->sl->ofd, buf, q - buf);
	409	}
	410
42da2a58	411	/* --- @t_destroy@ --- *
b9066fbb	412	*
	413	* Arguments: @tunnel *t@ = pointer to tunnel block
	414	*
	415	* Returns: ---
	416	*
	417	* Use: Destroys a tunnel.
	418	*/
	419
42da2a58	420	static void t_destroy(tunnel *t)
b9066fbb	421	{
98fdb08d	422	slipif *sl = t->sl;
98fdb08d	423
b9066fbb	424	/* --- If it reported EOF, leave it out-of-action --- */
b9066fbb	425
42da2a58	426	if (!(t->st & ST_EOF)) {
b9066fbb	427	sel_rmfile(&t->f);
42da2a58	428	sl->f &= ~F_INUSE;
98fdb08d	429	}
42da2a58	430	if (sl && (sl->f & F_DYNAMIC)) {
060ca767	431	T( trace(T_TUNNEL, "tun-slip: releasing dynamic slipif %s", sl->name); )
98fdb08d	432	close(sl->ofd);
	433	close(sl->ifd);
	434	kill(sl->kid, SIGTERM);
	435	xfree(sl->name);
	436	DESTROY(sl);
b9066fbb	437	}
42da2a58	438	DESTROY(t);
b9066fbb	439	}
b9066fbb	440
42da2a58	441	const tunnel_ops tun_slip = {
	442	"slip",
	443	t_init,
	444	t_create,
	445	t_ifname,
	446	t_inject,
	447	t_destroy
	448	};
	449
b9066fbb	450	/----- That's all, folks -------------------------------------------------/