[yaid] / yaid.c

/* -*-c-*-
 *
 * Main daemon
 *
 * (c) 2012 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of Yet Another Ident Daemon (YAID).
 *
 * YAID 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.
 *
 * YAID 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 YAID; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

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

#include "yaid.h"

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

struct listen {
  const struct addrops *ao;
  sel_file f;
};

#define WRBUFSZ 1024
struct writebuf {
  size_t o, n;
  sel_file wr;
  void (*func)(int, void *);
  void *p;
  unsigned char buf[WRBUFSZ];
};

struct proxy {
  struct client *c;
  int fd;
  conn cn;
  selbuf b;
  struct writebuf wb;
  char nat[ADDRLEN];
};

struct client {
  selbuf b;
  int fd;
  struct query q;
  struct listen *l;
  struct writebuf wb;
  struct proxy *px;
};

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

static sel_state sel;

static policy_v policy = DA_INIT;
static fwatch polfw;

static unsigned char tokenbuf[4096];
static size_t tokenptr = sizeof(tokenbuf);
static int randfd;

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

void logmsg(const struct query *q, int prio, const char *msg, ...)
{
  va_list ap;
  dstr d = DSTR_INIT;

  va_start(ap, msg);
  if (q) {
    dputsock(&d, q->ao, &q->s[L]);
    dstr_puts(&d, " <-> ");
    dputsock(&d, q->ao, &q->s[R]);
    dstr_puts(&d, ": ");
  }
  dstr_vputf(&d, msg, &ap);
  va_end(ap);
  fprintf(stderr, "yaid: %s\n", d.buf);
  dstr_destroy(&d);
}

static void write_out(int fd, unsigned mode, void *p)
{
  ssize_t n;
  struct writebuf *wb = p;

  if ((n = write(fd, wb->buf + wb->o, wb->n)) < 0) {
    if (errno == EAGAIN || errno == EWOULDBLOCK) return;
    wb->n = 0;
    sel_rmfile(&wb->wr);
    wb->func(errno, wb->p);
  }
  wb->o += n;
  wb->n -= n;
  if (!wb->n) {
    wb->o = 0;
    sel_rmfile(&wb->wr);
    wb->func(0, wb->p);
  }
}

static int queue_write(struct writebuf *wb, const void *p, size_t n)
{
  if (!n) return (0);
  if (wb->n - wb->o + n > WRBUFSZ) return (-1);
  if (wb->o) {
    memmove(wb->buf, wb->buf + wb->o, wb->n);
    wb->o = 0;
  }
  memcpy(wb->buf + wb->n, p, n);
  if (!wb->n) {
    sel_addfile(&wb->wr);
    sel_force(&wb->wr);
  }
  wb->n += n;
  return (0);
}

static void free_writebuf(struct writebuf *wb)
  { if (wb->n) sel_rmfile(&wb->wr); }

static void init_writebuf(struct writebuf *wb,
			  int fd, void (*func)(int, void *), void *p)
{
  sel_initfile(&sel, &wb->wr, fd, SEL_WRITE, write_out, wb);
  wb->func = func;
  wb->p = p;
  wb->n = wb->o = 0;
}

static void cancel_proxy(struct proxy *px)
{
  if (px->fd == -1)
    conn_kill(&px->cn);
  else {
    close(px->fd);
    selbuf_destroy(&px->b);
    free_writebuf(&px->wb);
  }
  selbuf_enable(&px->c->b);
  px->c->px = 0;
  xfree(px);
}

static void disconnect_client(struct client *c)
{
  close(c->fd);
  selbuf_destroy(&c->b);
  free_writebuf(&c->wb);
  if (c->px) cancel_proxy(c->px);
  xfree(c);
}

static void done_client_write(int err, void *p)
{
  struct client *c = p;

  if (!err)
    selbuf_enable(&c->b);
  else {
    logmsg(&c->q, LOG_ERR, "failed to send reply: %s", strerror(err));
    disconnect_client(c);
  }
}

static void write_to_client(struct client *c, const char *fmt, ...)
{
  va_list ap;
  char buf[WRBUFSZ];
  ssize_t n;

  va_start(ap, fmt);
  n = vsnprintf(buf, sizeof(buf), fmt, ap);
  if (n < 0) {
    logmsg(&c->q, LOG_ERR, "failed to format output: %s", strerror(errno));
    disconnect_client(c);
    return;
  } else if (n > sizeof(buf)) {
    logmsg(&c->q, LOG_ERR, "output too long for client send buffer");
    disconnect_client(c);
    return;
  }

  selbuf_disable(&c->b);
  if (queue_write(&c->wb, buf, n)) {
    logmsg(&c->q, LOG_ERR, "write buffer overflow");
    disconnect_client(c);
  }
}

static void reply(struct client *c, const char *ty, const char *msg)
{
  write_to_client(c, "%u,%u:%s:%s\r\n",
		  c->q.s[L].port, c->q.s[R].port, ty, msg);
}

const char *const errtok[] = {
#define DEFTOK(err, tok) tok,
  ERROR(DEFTOK)
#undef DEFTOK
};

static void reply_error(struct client *c, unsigned err)
{
  assert(err < E_LIMIT);
  reply(c, "ERROR", errtok[err]);
}

static void skipws(const char **pp)
  { while (isspace((unsigned char )**pp)) (*pp)++; }

static int idtoken(const char **pp, char *q, size_t n)
{
  const char *p = *pp;

  skipws(&p);
  n--;
  for (;;) {
    if (*p == ':' || *p <= 32 || *p >= 127) break;
    if (!n) return (-1);
    *q++ = *p++;
    n--;
  }
  *q++ = 0;
  *pp = p;
  return (0);
}

static int unum(const char **pp, unsigned *ii, unsigned min, unsigned max)
{
  char *q;
  unsigned long i;
  int e;

  skipws(pp);
  if (!isdigit((unsigned char)**pp)) return (-1);
  e = errno; errno = 0;
  i = strtoul(*pp, &q, 10);
  if (errno) return (-1);
  *pp = q;
  errno = e;
  if (i < min || i > max) return (-1);
  *ii = i;
  return (0);
}

static void proxy_line(char *line, size_t sz, void *p)
{
  struct proxy *px = p;
  char buf[1024];
  const char *q = line;
  unsigned lp, rp;

  while (sz && isspace((unsigned char)line[sz - 1])) sz--;
  printf("received proxy line from %s: %s\n", px->nat, line);

  if (unum(&q, &lp, 1, 65535)) goto syntax;
  skipws(&q); if (*q != ',') goto syntax; q++;
  if (unum(&q, &rp, 1, 65535)) goto syntax;
  skipws(&q); if (*q != ':') goto syntax; q++;
  if (lp != px->c->q.u.nat.port || rp != px->c->q.s[R].port) goto syntax;
  if (idtoken(&q, buf, sizeof(buf))) goto syntax;
  skipws(&q); if (*q != ':') goto syntax; q++;
  if (strcmp(buf, "ERROR") == 0) {
    skipws(&q);
    logmsg(&px->c->q, LOG_ERR, "proxy error from %s: %s", px->nat, q);
    reply(px->c, "ERROR", q);
  } else if (strcmp(buf, "USERID") == 0) {
    if (idtoken(&q, buf, sizeof(buf))) goto syntax;
    skipws(&q); if (*q != ':') goto syntax; q++;
    skipws(&q);
    logmsg(&px->c->q, LOG_ERR, "user `%s'; proxy = %s, os = %s",
	   q, px->nat, buf);
    write_to_client(px->c, "%u,%u:USERID:%s:%s\r\n",
		    px->c->q.s[L].port, px->c->q.s[R].port, buf, q);
  } else
    goto syntax;
  goto done;

syntax:
  logmsg(&px->c->q, LOG_ERR, "failed to parse response from %s", px->nat);
  reply_error(px->c, E_UNKNOWN);
done:
  cancel_proxy(px);
}

static void done_proxy_write(int err, void *p)
{
  struct proxy *px = p;

  if (err) {
    logmsg(&px->c->q, LOG_ERR, "failed to proxy query to %s: %s",
	   px->nat, strerror(errno));
    reply_error(px->c, E_UNKNOWN);
    cancel_proxy(px);
    return;
  }
  selbuf_enable(&px->b);
}

static void proxy_connected(int fd, void *p)
{
  struct proxy *px = p;
  char buf[16];
  int n;

  if (fd < 0) {
    logmsg(&px->c->q, LOG_ERR,
	   "failed to make %s proxy connection to %s: %s",
	   px->c->l->ao->name, px->nat, strerror(errno));
    reply_error(px->c, E_UNKNOWN);
    cancel_proxy(px);
    return;
  }

  px->fd = fd;
  selbuf_init(&px->b, &sel, fd, proxy_line, px);
  selbuf_setsize(&px->b, 1024);
  selbuf_disable(&px->b);
  init_writebuf(&px->wb, fd, done_proxy_write, px);

  n = sprintf(buf, "%u,%u\r\n", px->c->q.u.nat.port, px->c->q.s[R].port);
  queue_write(&px->wb, buf, n);
}

static void proxy_query(struct client *c)
{
  struct socket s;
  struct sockaddr_storage ss;
  size_t ssz;
  struct proxy *px;
  int fd;

  px = xmalloc(sizeof(*px));
  inet_ntop(c->q.ao->af, &c->q.u.nat.addr, px->nat, sizeof(px->nat));

  if ((fd = socket(c->q.ao->af, SOCK_STREAM, 0)) < 0) {
    logmsg(&c->q, LOG_ERR, "failed to make %s socket for proxy: %s",
	   c->l->ao->name, strerror(errno));
    goto err_0;
  }

  if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) {
    logmsg(&c->q, LOG_ERR, "failed to set %s proxy socket nonblocking: %s",
	   c->l->ao->name, strerror(errno));
    goto err_1;
  }

  s = c->q.u.nat;
  s.port = 113;
  c->l->ao->socket_to_sockaddr(&s, &ss, &ssz);
  selbuf_disable(&c->b);
  if (conn_init(&px->cn, &sel, fd, (struct sockaddr *)&ss, ssz,
		proxy_connected, px)) {
    logmsg(&c->q, LOG_ERR, "failed to make %s proxy connection to %s: %s",
	   c->l->ao->name, px->nat, strerror(errno));
    goto err_2;
  }

  c->px = px; px->c = c;
  px->fd = -1;
  return;

err_2:
  selbuf_enable(&c->b);
err_1:
  close(px->fd);
err_0:
  xfree(px);
  reply_error(c, E_UNKNOWN);
}

static const struct policy default_policy = POLICY_INIT(A_NAME);

static void user_token(char *p)
{
  static const char tokmap[64] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-";
  unsigned a = 0;
  unsigned b = 0;
  int i;
#define TOKENSZ 8

  if (tokenptr + TOKENSZ >= sizeof(tokenbuf)) {
    if (read(randfd, tokenbuf, sizeof(tokenbuf)) < sizeof(tokenbuf))
      die(1, "unexpected short read or error from `/dev/urandom'");
    tokenptr = 0;
  }

  for (i = 0; i < TOKENSZ; i++) {
    a = (a << 8) | tokenbuf[tokenptr++]; b += 8;
    while (b >= 6) {
      b -= 6;
      *p++ = tokmap[(a >> b) & 0x3f];
    }
  }
  if (b)
    *p++ = tokmap[(a << (6 - b)) & 0x3f];
  *p++ = 0;
}

static void client_line(char *line, size_t len, void *p)
{
  struct client *c = p;
  const char *q;
  struct passwd *pw = 0;
  const struct policy *pol;
  dstr d = DSTR_INIT;
  struct policy upol = POLICY_INIT(A_LIMIT);
  struct policy_file pf;
  char buf[16];
  int i;

  c->q.s[L].port = c->q.s[R].port = 0;
  if (!line) {
    disconnect_client(c);
    return;
  }

  if (fwatch_update(&polfw, "yaid.policy")) {
    logmsg(0, LOG_INFO, "reload master policy file `%s'", "yaid.policy");
    load_policy_file("yaid.policy", &policy);
  }

  q = line;
  if (unum(&q, &c->q.s[L].port, 1, 65535)) goto bad;
  skipws(&q); if (*q != ',') goto bad; q++;
  if (unum(&q, &c->q.s[R].port, 1, 65535)) goto bad;
  skipws(&q); if (*q) goto bad;

  identify(&c->q);
  switch (c->q.resp) {
    case R_UID:
      if ((pw = getpwuid(c->q.u.uid)) == 0) {
	logmsg(&c->q, LOG_ERR, "no passwd entry for user %d", c->q.u.uid);
	reply_error(c, E_NOUSER);
	return;
      }
      break;
    case R_NAT:
      proxy_query(c);
      return;
    case R_ERROR:
      /* Should already be logged. */
      reply_error(c, c->q.u.error);
      return;
    default:
      abort();
  }

  for (i = 0; i < DA_LEN(&policy); i++) {
    pol = &DA(&policy)[i];
    if (!match_policy(pol, &c->q)) continue;
    if (pol->act.act != A_USER)
      goto match;
    DRESET(&d);
    dstr_putf(&d, "%s/.yaid.policy", pw->pw_dir);
    if (open_policy_file(&pf, d.buf, "user policy file", &c->q))
      continue;
    while (!read_policy_file(&pf)) {
      if (pf.lno > 100) {
	logmsg(&c->q, LOG_ERR, "%s:%d: user policy file too long",
	       pf.name, pf.lno);
	break;
      }
      if (!match_policy(&pf.p, &c->q)) continue;
      if (!(pol->act.u.user & (1 << pf.p.act.act))) {
	logmsg(&c->q, LOG_ERR,
	       "%s:%d: user action forbidden by global policy",
	       pf.name, pf.lno);
	continue;
      }
      upol = pf.p; pol = &upol;
      init_policy(&pf.p);
      close_policy_file(&pf);
      goto match;
    }
    close_policy_file(&pf);
  }
  pol = &default_policy;

match:
  DDESTROY(&d);
  switch (pol->act.act) {
    case A_NAME:
      logmsg(&c->q, LOG_INFO, "user `%s' (%d)", pw->pw_name, c->q.u.uid);
      reply(c, "USERID:UNIX", pw->pw_name);
      break;
    case A_TOKEN:
      user_token(buf);
      logmsg(&c->q, LOG_INFO, "user `%s' (%d); token = %s",
	     pw->pw_name, c->q.u.uid, buf);
      reply(c, "USERID:OTHER", buf);
      break;
    case A_DENY:
      logmsg(&c->q, LOG_INFO, "user `%s' (%d); denying",
	     pw->pw_name, c->q.u.uid);
      break;
    case A_HIDE:
      logmsg(&c->q, LOG_INFO, "user `%s' (%d); hiding",
	     pw->pw_name, c->q.u.uid);
      reply_error(c, E_HIDDEN);
      break;
    case A_LIE:
      logmsg(&c->q, LOG_INFO, "user `%s' (%d); lie = `%s'",
	     pw->pw_name, c->q.u.uid, pol->act.u.lie);
      reply(c, "USERID:UNIX", pol->act.u.lie);
      break;
    default:
      abort();
  }

  free_policy(&upol);
  return;

bad:
  logmsg(&c->q, LOG_ERR, "failed to parse query from client");
  disconnect_client(c);
}

static void accept_client(int fd, unsigned mode, void *p)
{
  struct listen *l = p;
  struct client *c;
  struct sockaddr_storage ssr, ssl;
  size_t ssz = sizeof(ssr);
  int sk;

  if ((sk = accept(fd, (struct sockaddr *)&ssr, &ssz)) < 0) {
    if (errno != EAGAIN && errno == EWOULDBLOCK) {
      logmsg(0, LOG_ERR, "failed to accept incoming %s connection: %s",
	     l->ao->name, strerror(errno));
    }
    return;
  }

  c = xmalloc(sizeof(*c));
  c->l = l;
  c->q.ao = l->ao;
  l->ao->sockaddr_to_addr(&ssr, &c->q.s[R].addr);
  ssz = sizeof(ssl);
  if (getsockname(sk, (struct sockaddr *)&ssl, &ssz)) {
    logmsg(0, LOG_ERR,
	   "failed to read local address for incoming %s connection: %s",
	   l->ao->name, strerror(errno));
    close(sk);
    xfree(c);
    return;
  }
  l->ao->sockaddr_to_addr(&ssl, &c->q.s[L].addr);
  c->q.s[L].port = c->q.s[R].port = 0;

  /* logmsg(&c->q, LOG_INFO, "accepted %s connection", l->ao->name); */

  selbuf_init(&c->b, &sel, sk, client_line, c);
  selbuf_setsize(&c->b, 1024);
  c->fd = sk;
  c->px = 0;
  init_writebuf(&c->wb, sk, done_client_write, c);
}

static int make_listening_socket(const struct addrops *ao, int port)
{
  int fd;
  int yes = 1;
  struct socket s;
  struct sockaddr_storage ss;
  struct listen *l;
  size_t ssz;

  if ((fd = socket(ao->af, SOCK_STREAM, 0)) < 0) {
    if (errno == EAFNOSUPPORT) return (-1);
    die(1, "failed to create %s listening socket: %s",
	ao->name, strerror(errno));
  }
  setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
  s.addr = *ao->any;
  s.port = port;
  ao->socket_to_sockaddr(&s, &ss, &ssz);
  if (ao->init_listen_socket(fd)) {
    die(1, "failed to initialize %s listening socket: %s",
	ao->name, strerror(errno));
  }
  if (bind(fd, (struct sockaddr *)&ss, ssz)) {
    die(1, "failed to bind %s listening socket: %s",
	ao->name, strerror(errno));
  }
  if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) {
    die(1, "failed to set %s listening socket nonblocking: %s",
	ao->name, strerror(errno));
  }
  if (listen(fd, 5))
    die(1, "failed to listen for %s: %s", ao->name, strerror(errno));

  l = xmalloc(sizeof(*l));
  l->ao = ao;
  sel_initfile(&sel, &l->f, fd, SEL_READ, accept_client, l);
  sel_addfile(&l->f);

  return (0);
}

int main(int argc, char *argv[])
{
  int port = 113;
  const struct addrops *ao;
  int any = 0;

  ego(argv[0]);

  fwatch_init(&polfw, "yaid.policy");
  if (load_policy_file("yaid.policy", &policy))
    exit(1);
  { int i;
    for (i = 0; i < DA_LEN(&policy); i++)
      print_policy(&DA(&policy)[i]);
  }

  if ((randfd = open("/dev/urandom", O_RDONLY)) < 0) {
    die(1, "failed to open `/dev/urandom' for reading: %s",
	strerror(errno));
  }

  sel_init(&sel);
  for (ao = addroptab; ao->name; ao++)
    if (!make_listening_socket(ao, port)) any = 1;
  if (!any)
    die(1, "no IP protocols supported");

  for (;;)
    if (sel_select(&sel)) die(1, "select failed: %s", strerror(errno));

  return (0);
}

/*----- That's all, folks -------------------------------------------------*/
Commit	Line	Data
9da480be MW	1	/* --c--
	2	*
	3	* Main daemon
	4	*
	5	* (c) 2012 Straylight/Edgeware
	6	*/
	7
	8	/----- Licensing notice --------------------------------------------------
	9	*
	10	* This file is part of Yet Another Ident Daemon (YAID).
	11	*
	12	* YAID is free software; you can redistribute it and/or modify
	13	* it under the terms of the GNU General Public License as published by
	14	* the Free Software Foundation; either version 2 of the License, or
	15	* (at your option) any later version.
	16	*
	17	* YAID is distributed in the hope that it will be useful,
	18	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	20	* GNU General Public License for more details.
	21	*
	22	* You should have received a copy of the GNU General Public License
	23	* along with YAID; if not, write to the Free Software Foundation,
	24	* Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	25	*/
	26
	27	/----- Header files ------------------------------------------------------/
	28
	29	#include "yaid.h"
	30
	31	/----- Data structures ---------------------------------------------------/
	32
	33	struct listen {
bf4d9761	34	const struct addrops *ao;
9da480be MW	35	sel_file f;
	36	};
	37
	38	#define WRBUFSZ 1024
	39	struct writebuf {
	40	size_t o, n;
	41	sel_file wr;
	42	void (func)(int, void );
	43	void *p;
	44	unsigned char buf[WRBUFSZ];
	45	};
	46
	47	struct proxy {
	48	struct client *c;
	49	int fd;
	50	conn cn;
	51	selbuf b;
	52	struct writebuf wb;
	53	char nat[ADDRLEN];
	54	};
	55
	56	struct client {
	57	selbuf b;
	58	int fd;
	59	struct query q;
	60	struct listen *l;
	61	struct writebuf wb;
	62	struct proxy *px;
	63	};
	64
	65	/----- Static variables --------------------------------------------------/
	66
	67	static sel_state sel;
	68
	69	static policy_v policy = DA_INIT;
	70	static fwatch polfw;
	71
	72	static unsigned char tokenbuf[4096];
	73	static size_t tokenptr = sizeof(tokenbuf);
	74	static int randfd;
	75
	76	/----- Main code ---------------------------------------------------------/
	77
9da480be MW	78	void logmsg(const struct query q, int prio, const char msg, ...)
	79	{
	80	va_list ap;
	81	dstr d = DSTR_INIT;
	82
	83	va_start(ap, msg);
	84	if (q) {
bf4d9761	85	dputsock(&d, q->ao, &q->s[L]);
9da480be	86	dstr_puts(&d, " <-> ");
bf4d9761	87	dputsock(&d, q->ao, &q->s[R]);
9da480be MW	88	dstr_puts(&d, ": ");
	89	}
	90	dstr_vputf(&d, msg, &ap);
	91	va_end(ap);
	92	fprintf(stderr, "yaid: %s\n", d.buf);
	93	dstr_destroy(&d);
	94	}
	95
	96	static void write_out(int fd, unsigned mode, void *p)
	97	{
	98	ssize_t n;
	99	struct writebuf *wb = p;
	100
	101	if ((n = write(fd, wb->buf + wb->o, wb->n)) < 0) {
	102	if (errno == EAGAIN \|\| errno == EWOULDBLOCK) return;
	103	wb->n = 0;
	104	sel_rmfile(&wb->wr);
	105	wb->func(errno, wb->p);
	106	}
	107	wb->o += n;
	108	wb->n -= n;
	109	if (!wb->n) {
	110	wb->o = 0;
	111	sel_rmfile(&wb->wr);
	112	wb->func(0, wb->p);
	113	}
	114	}
	115
	116	static int queue_write(struct writebuf wb, const void p, size_t n)
	117	{
	118	if (!n) return (0);
	119	if (wb->n - wb->o + n > WRBUFSZ) return (-1);
	120	if (wb->o) {
	121	memmove(wb->buf, wb->buf + wb->o, wb->n);
	122	wb->o = 0;
	123	}
	124	memcpy(wb->buf + wb->n, p, n);
	125	if (!wb->n) {
	126	sel_addfile(&wb->wr);
	127	sel_force(&wb->wr);
	128	}
	129	wb->n += n;
	130	return (0);
	131	}
	132
	133	static void free_writebuf(struct writebuf *wb)
	134	{ if (wb->n) sel_rmfile(&wb->wr); }
	135
	136	static void init_writebuf(struct writebuf *wb,
	137	int fd, void (func)(int, void ), void *p)
	138	{
	139	sel_initfile(&sel, &wb->wr, fd, SEL_WRITE, write_out, wb);
	140	wb->func = func;
	141	wb->p = p;
	142	wb->n = wb->o = 0;
	143	}
	144
	145	static void cancel_proxy(struct proxy *px)
	146	{
	147	if (px->fd == -1)
	148	conn_kill(&px->cn);
	149	else {
	150	close(px->fd);
	151	selbuf_destroy(&px->b);
152	free_writebuf(&px->wb);
153	}
154	selbuf_enable(&px->c->b);
155	px->c->px = 0;
156	xfree(px);
157	}
158
159	static void disconnect_client(struct client *c)
160	{
161	close(c->fd);
162	selbuf_destroy(&c->b);
163	free_writebuf(&c->wb);
164	if (c->px) cancel_proxy(c->px);
165	xfree(c);
166	}
167
168	static void done_client_write(int err, void *p)
169	{
170	struct client *c = p;
171
172	if (!err)
173	selbuf_enable(&c->b);
174	else {
175	logmsg(&c->q, LOG_ERR, "failed to send reply: %s", strerror(err));
176	disconnect_client(c);
177	}
178	}
179
180	static void write_to_client(struct client c, const char fmt, ...)
181	{
182	va_list ap;
183	char buf[WRBUFSZ];
184	ssize_t n;
185
186	va_start(ap, fmt);
187	n = vsnprintf(buf, sizeof(buf), fmt, ap);
188	if (n < 0) {
189	logmsg(&c->q, LOG_ERR, "failed to format output: %s", strerror(errno));
190	disconnect_client(c);
191	return;
192	} else if (n > sizeof(buf)) {
193	logmsg(&c->q, LOG_ERR, "output too long for client send buffer");
194	disconnect_client(c);
195	return;
196	}
197
198	selbuf_disable(&c->b);
199	if (queue_write(&c->wb, buf, n)) {
200	logmsg(&c->q, LOG_ERR, "write buffer overflow");
201	disconnect_client(c);
202	}
203	}
204
205	static void reply(struct client c, const char ty, const char *msg)
206	{
207	write_to_client(c, "%u,%u:%s:%s\r\n",
208	c->q.s[L].port, c->q.s[R].port, ty, msg);
209	}
210
bf4d9761 MW	211	const char *const errtok[] = {
	212	#define DEFTOK(err, tok) tok,
	213	ERROR(DEFTOK)
	214	#undef DEFTOK
	215	};
	216
9da480be MW	217	static void reply_error(struct client *c, unsigned err)
	218	{
	219	assert(err < E_LIMIT);
	220	reply(c, "ERROR", errtok[err]);
	221	}
	222
	223	static void skipws(const char **pp)
	224	{ while (isspace((unsigned char )*pp)) (pp)++; }
	225
	226	static int idtoken(const char *pp, char q, size_t n)
	227	{
	228	const char p = pp;
	229
	230	skipws(&p);
	231	n--;
	232	for (;;) {
	233	if (p == ':' \|\| p <= 32 \|\| *p >= 127) break;
	234	if (!n) return (-1);
	235	q++ = p++;
	236	n--;
	237	}
	238	*q++ = 0;
	239	*pp = p;
	240	return (0);
	241	}
	242
	243	static int unum(const char *pp, unsigned ii, unsigned min, unsigned max)
	244	{
	245	char *q;
	246	unsigned long i;
	247	int e;
	248
	249	skipws(pp);
	250	if (!isdigit((unsigned char)**pp)) return (-1);
	251	e = errno; errno = 0;
	252	i = strtoul(*pp, &q, 10);
	253	if (errno) return (-1);
	254	*pp = q;
	255	errno = e;
	256	if (i < min \|\| i > max) return (-1);
	257	*ii = i;
	258	return (0);
	259	}
	260
	261	static void proxy_line(char line, size_t sz, void p)
	262	{
	263	struct proxy *px = p;
	264	char buf[1024];
	265	const char *q = line;
	266	unsigned lp, rp;
	267
	268	while (sz && isspace((unsigned char)line[sz - 1])) sz--;
	269	printf("received proxy line from %s: %s\n", px->nat, line);
	270
	271	if (unum(&q, &lp, 1, 65535)) goto syntax;
	272	skipws(&q); if (*q != ',') goto syntax; q++;
	273	if (unum(&q, &rp, 1, 65535)) goto syntax;
	274	skipws(&q); if (*q != ':') goto syntax; q++;
	275	if (lp != px->c->q.u.nat.port \|\| rp != px->c->q.s[R].port) goto syntax;
	276	if (idtoken(&q, buf, sizeof(buf))) goto syntax;
	277	skipws(&q); if (*q != ':') goto syntax; q++;
	278	if (strcmp(buf, "ERROR") == 0) {
	279	skipws(&q);
	280	logmsg(&px->c->q, LOG_ERR, "proxy error from %s: %s", px->nat, q);
281	reply(px->c, "ERROR", q);
282	} else if (strcmp(buf, "USERID") == 0) {
283	if (idtoken(&q, buf, sizeof(buf))) goto syntax;
284	skipws(&q); if (*q != ':') goto syntax; q++;
285	skipws(&q);
286	logmsg(&px->c->q, LOG_ERR, "user `%s'; proxy = %s, os = %s",
287	q, px->nat, buf);
288	write_to_client(px->c, "%u,%u:USERID:%s:%s\r\n",
289	px->c->q.s[L].port, px->c->q.s[R].port, buf, q);
290	} else
291	goto syntax;
292	goto done;
293
294	syntax:
295	logmsg(&px->c->q, LOG_ERR, "failed to parse response from %s", px->nat);
296	reply_error(px->c, E_UNKNOWN);
297	done:
298	cancel_proxy(px);
299	}
300
301	static void done_proxy_write(int err, void *p)
302	{
303	struct proxy *px = p;
304
305	if (err) {
306	logmsg(&px->c->q, LOG_ERR, "failed to proxy query to %s: %s",
307	px->nat, strerror(errno));
308	reply_error(px->c, E_UNKNOWN);
309	cancel_proxy(px);
310	return;
311	}
312	selbuf_enable(&px->b);
313	}
314
315	static void proxy_connected(int fd, void *p)
316	{
317	struct proxy *px = p;
318	char buf[16];
319	int n;
320
321	if (fd < 0) {
322	logmsg(&px->c->q, LOG_ERR,
323	"failed to make %s proxy connection to %s: %s",
bf4d9761	324	px->c->l->ao->name, px->nat, strerror(errno));
9da480be MW	325	reply_error(px->c, E_UNKNOWN);
	326	cancel_proxy(px);
	327	return;
	328	}
	329
	330	px->fd = fd;
	331	selbuf_init(&px->b, &sel, fd, proxy_line, px);
	332	selbuf_setsize(&px->b, 1024);
	333	selbuf_disable(&px->b);
	334	init_writebuf(&px->wb, fd, done_proxy_write, px);
	335
	336	n = sprintf(buf, "%u,%u\r\n", px->c->q.u.nat.port, px->c->q.s[R].port);
	337	queue_write(&px->wb, buf, n);
	338	}
	339
	340	static void proxy_query(struct client *c)
	341	{
	342	struct socket s;
	343	struct sockaddr_storage ss;
	344	size_t ssz;
	345	struct proxy *px;
9da480be MW	346	int fd;
	347
	348	px = xmalloc(sizeof(*px));
bf4d9761	349	inet_ntop(c->q.ao->af, &c->q.u.nat.addr, px->nat, sizeof(px->nat));
9da480be	350
bf4d9761	351	if ((fd = socket(c->q.ao->af, SOCK_STREAM, 0)) < 0) {
9da480be	352	logmsg(&c->q, LOG_ERR, "failed to make %s socket for proxy: %s",
bf4d9761	353	c->l->ao->name, strerror(errno));
9da480be MW	354	goto err_0;
	355	}
	356
bf4d9761	357	if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) {
9da480be	358	logmsg(&c->q, LOG_ERR, "failed to set %s proxy socket nonblocking: %s",
bf4d9761	359	c->l->ao->name, strerror(errno));
9da480be MW	360	goto err_1;
	361	}
	362
	363	s = c->q.u.nat;
	364	s.port = 113;
bf4d9761	365	c->l->ao->socket_to_sockaddr(&s, &ss, &ssz);
9da480be MW	366	selbuf_disable(&c->b);
	367	if (conn_init(&px->cn, &sel, fd, (struct sockaddr *)&ss, ssz,
	368	proxy_connected, px)) {
	369	logmsg(&c->q, LOG_ERR, "failed to make %s proxy connection to %s: %s",
bf4d9761	370	c->l->ao->name, px->nat, strerror(errno));
9da480be MW	371	goto err_2;
	372	}
	373
	374	c->px = px; px->c = c;
	375	px->fd = -1;
	376	return;
	377
	378	err_2:
	379	selbuf_enable(&c->b);
	380	err_1:
	381	close(px->fd);
	382	err_0:
	383	xfree(px);
	384	reply_error(c, E_UNKNOWN);
	385	}
	386
	387	static const struct policy default_policy = POLICY_INIT(A_NAME);
	388
	389	static void user_token(char *p)
	390	{
	391	static const char tokmap[64] =
	392	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-";
	393	unsigned a = 0;
	394	unsigned b = 0;
	395	int i;
	396	#define TOKENSZ 8
	397
	398	if (tokenptr + TOKENSZ >= sizeof(tokenbuf)) {
	399	if (read(randfd, tokenbuf, sizeof(tokenbuf)) < sizeof(tokenbuf))
	400	die(1, "unexpected short read or error from `/dev/urandom'");
	401	tokenptr = 0;
	402	}
	403
	404	for (i = 0; i < TOKENSZ; i++) {
	405	a = (a << 8) \| tokenbuf[tokenptr++]; b += 8;
	406	while (b >= 6) {
	407	b -= 6;
	408	*p++ = tokmap[(a >> b) & 0x3f];
	409	}
	410	}
	411	if (b)
	412	*p++ = tokmap[(a << (6 - b)) & 0x3f];
	413	*p++ = 0;
	414	}
	415
	416	static void client_line(char line, size_t len, void p)
	417	{
	418	struct client *c = p;
	419	const char *q;
	420	struct passwd *pw = 0;
	421	const struct policy *pol;
	422	dstr d = DSTR_INIT;
	423	struct policy upol = POLICY_INIT(A_LIMIT);
	424	struct policy_file pf;
	425	char buf[16];
	426	int i;
	427
	428	c->q.s[L].port = c->q.s[R].port = 0;
	429	if (!line) {
	430	disconnect_client(c);
	431	return;
	432	}
	433
	434	if (fwatch_update(&polfw, "yaid.policy")) {
435	logmsg(0, LOG_INFO, "reload master policy file `%s'", "yaid.policy");
436	load_policy_file("yaid.policy", &policy);
437	}
438
439	q = line;
440	if (unum(&q, &c->q.s[L].port, 1, 65535)) goto bad;
441	skipws(&q); if (*q != ',') goto bad; q++;
442	if (unum(&q, &c->q.s[R].port, 1, 65535)) goto bad;
443	skipws(&q); if (*q) goto bad;
444
445	identify(&c->q);
446	switch (c->q.resp) {
447	case R_UID:
448	if ((pw = getpwuid(c->q.u.uid)) == 0) {
449	logmsg(&c->q, LOG_ERR, "no passwd entry for user %d", c->q.u.uid);
450	reply_error(c, E_NOUSER);
451	return;
452	}
453	break;
454	case R_NAT:
455	proxy_query(c);
456	return;
457	case R_ERROR:
458	/* Should already be logged. */
459	reply_error(c, c->q.u.error);
460	return;
461	default:
462	abort();
463	}
464
465	for (i = 0; i < DA_LEN(&policy); i++) {
466	pol = &DA(&policy)[i];
467	if (!match_policy(pol, &c->q)) continue;
468	if (pol->act.act != A_USER)
469	goto match;
470	DRESET(&d);
471	dstr_putf(&d, "%s/.yaid.policy", pw->pw_dir);
472	if (open_policy_file(&pf, d.buf, "user policy file", &c->q))
473	continue;
474	while (!read_policy_file(&pf)) {
475	if (pf.lno > 100) {
476	logmsg(&c->q, LOG_ERR, "%s:%d: user policy file too long",
477	pf.name, pf.lno);
478	break;
479	}
480	if (!match_policy(&pf.p, &c->q)) continue;
481	if (!(pol->act.u.user & (1 << pf.p.act.act))) {
482	logmsg(&c->q, LOG_ERR,
483	"%s:%d: user action forbidden by global policy",
484	pf.name, pf.lno);
485	continue;
486	}
487	upol = pf.p; pol = &upol;
488	init_policy(&pf.p);
489	close_policy_file(&pf);
490	goto match;
491	}
492	close_policy_file(&pf);
493	}
494	pol = &default_policy;
495
496	match:
497	DDESTROY(&d);
498	switch (pol->act.act) {
499	case A_NAME:
500	logmsg(&c->q, LOG_INFO, "user `%s' (%d)", pw->pw_name, c->q.u.uid);
501	reply(c, "USERID:UNIX", pw->pw_name);
502	break;
503	case A_TOKEN:
504	user_token(buf);
505	logmsg(&c->q, LOG_INFO, "user `%s' (%d); token = %s",
506	pw->pw_name, c->q.u.uid, buf);
507	reply(c, "USERID:OTHER", buf);
508	break;
509	case A_DENY:
510	logmsg(&c->q, LOG_INFO, "user `%s' (%d); denying",
511	pw->pw_name, c->q.u.uid);
512	break;
513	case A_HIDE:
514	logmsg(&c->q, LOG_INFO, "user `%s' (%d); hiding",
515	pw->pw_name, c->q.u.uid);
516	reply_error(c, E_HIDDEN);
517	break;
518	case A_LIE:
519	logmsg(&c->q, LOG_INFO, "user `%s' (%d); lie = `%s'",
520	pw->pw_name, c->q.u.uid, pol->act.u.lie);
521	reply(c, "USERID:UNIX", pol->act.u.lie);
522	break;
523	default:
524	abort();
525	}
526
527	free_policy(&upol);
528	return;
529
530	bad:
531	logmsg(&c->q, LOG_ERR, "failed to parse query from client");
532	disconnect_client(c);
533	}
534
535	static void accept_client(int fd, unsigned mode, void *p)
536	{
537	struct listen *l = p;
538	struct client *c;
539	struct sockaddr_storage ssr, ssl;
540	size_t ssz = sizeof(ssr);
541	int sk;
542
543	if ((sk = accept(fd, (struct sockaddr *)&ssr, &ssz)) < 0) {
544	if (errno != EAGAIN && errno == EWOULDBLOCK) {
545	logmsg(0, LOG_ERR, "failed to accept incoming %s connection: %s",
bf4d9761	546	l->ao->name, strerror(errno));
9da480be MW	547	}
	548	return;
	549	}
	550
	551	c = xmalloc(sizeof(*c));
	552	c->l = l;
bf4d9761 MW	553	c->q.ao = l->ao;
bf4d9761 MW	554	l->ao->sockaddr_to_addr(&ssr, &c->q.s[R].addr);
9da480be MW	555	ssz = sizeof(ssl);
	556	if (getsockname(sk, (struct sockaddr *)&ssl, &ssz)) {
	557	logmsg(0, LOG_ERR,
	558	"failed to read local address for incoming %s connection: %s",
bf4d9761	559	l->ao->name, strerror(errno));
9da480be MW	560	close(sk);
	561	xfree(c);
	562	return;
	563	}
bf4d9761	564	l->ao->sockaddr_to_addr(&ssl, &c->q.s[L].addr);
9da480be MW	565	c->q.s[L].port = c->q.s[R].port = 0;
9da480be MW	566
bf4d9761	567	/* logmsg(&c->q, LOG_INFO, "accepted %s connection", l->ao->name); */
9da480be MW	568
	569	selbuf_init(&c->b, &sel, sk, client_line, c);
	570	selbuf_setsize(&c->b, 1024);
	571	c->fd = sk;
	572	c->px = 0;
	573	init_writebuf(&c->wb, sk, done_client_write, c);
	574	}
	575
bf4d9761	576	static int make_listening_socket(const struct addrops *ao, int port)
9da480be MW	577	{
9da480be MW	578	int fd;
bf4d9761 MW	579	int yes = 1;
bf4d9761 MW	580	struct socket s;
9da480be MW	581	struct sockaddr_storage ss;
	582	struct listen *l;
	583	size_t ssz;
	584
bf4d9761	585	if ((fd = socket(ao->af, SOCK_STREAM, 0)) < 0) {
a20696ca	586	if (errno == EAFNOSUPPORT) return (-1);
9da480be	587	die(1, "failed to create %s listening socket: %s",
bf4d9761	588	ao->name, strerror(errno));
9da480be	589	}
bf4d9761 MW	590	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes));
	591	s.addr = *ao->any;
	592	s.port = port;
	593	ao->socket_to_sockaddr(&s, &ss, &ssz);
	594	if (ao->init_listen_socket(fd)) {
	595	die(1, "failed to initialize %s listening socket: %s",
	596	ao->name, strerror(errno));
	597	}
	598	if (bind(fd, (struct sockaddr *)&ss, ssz)) {
	599	die(1, "failed to bind %s listening socket: %s",
	600	ao->name, strerror(errno));
9da480be	601	}
bf4d9761	602	if (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)) {
9da480be	603	die(1, "failed to set %s listening socket nonblocking: %s",
bf4d9761	604	ao->name, strerror(errno));
9da480be MW	605	}
9da480be MW	606	if (listen(fd, 5))
bf4d9761	607	die(1, "failed to listen for %s: %s", ao->name, strerror(errno));
9da480be MW	608
9da480be MW	609	l = xmalloc(sizeof(*l));
bf4d9761	610	l->ao = ao;
9da480be MW	611	sel_initfile(&sel, &l->f, fd, SEL_READ, accept_client, l);
	612	sel_addfile(&l->f);
	613
a20696ca	614	return (0);
9da480be MW	615	}
	616
	617	int main(int argc, char *argv[])
	618	{
	619	int port = 113;
bf4d9761 MW	620	const struct addrops *ao;
bf4d9761 MW	621	int any = 0;
9da480be MW	622
	623	ego(argv[0]);
	624
	625	fwatch_init(&polfw, "yaid.policy");
	626	if (load_policy_file("yaid.policy", &policy))
	627	exit(1);
	628	{ int i;
	629	for (i = 0; i < DA_LEN(&policy); i++)
	630	print_policy(&DA(&policy)[i]);
	631	}
	632
	633	if ((randfd = open("/dev/urandom", O_RDONLY)) < 0) {
	634	die(1, "failed to open `/dev/urandom' for reading: %s",
	635	strerror(errno));
	636	}
	637
9da480be	638	sel_init(&sel);
bf4d9761 MW	639	for (ao = addroptab; ao->name; ao++)
	640	if (!make_listening_socket(ao, port)) any = 1;
	641	if (!any)
a20696ca	642	die(1, "no IP protocols supported");
9da480be MW	643
	644	for (;;)
	645	if (sel_select(&sel)) die(1, "select failed: %s", strerror(errno));
	646
	647	return (0);
	648	}
	649
	650	/----- That's all, folks -------------------------------------------------/