servutil: Implement version number comparison.

[tripe] / server / servutil.c

/* -*-c-*-
 *
 * $Id$
 *
 * Various handy server-only utilities
 *
 * (c) 2001 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 ------------------------------------------------------*/

#include "tripe.h"

/*----- Global variables --------------------------------------------------*/

octet buf_i[PKBUFSZ], buf_o[PKBUFSZ], buf_t[PKBUFSZ];

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

/* --- @mpstr@ --- *
 *
 * Arguments:	@mp *m@ = a multiprecision integer
 *
 * Returns:	A pointer to the integer's textual representation.
 *
 * Use:		Converts a multiprecision integer to a string.  Corrupts
 *		@buf_t@.
 */

const char *mpstr(mp *m)
{
  if (mp_writestring(m, (char *)buf_t, sizeof(buf_t), 10))
    return ("<failed>");
  return ((const char *)buf_t);
}

/* --- @gestr@ --- *
 *
 * Arguments:	@group *g@ = a group
 *		@ge *x@ = a group element
 *
 * Returns:	A pointer to the element's textual representation.
 *
 * Use:		Converts a group element to a string.  Corrupts
 *		@buf_t@.
 */

const char *gestr(group *g, ge *x)
{
  if (group_writestring(g, x, (char *)buf_t, sizeof(buf_t)))
    return ("<failed>");
  return ((const char *)buf_t);
}

/* --- @timestr@ --- *
 *
 * Arguments:	@time_t t@ = a time to convert
 *
 * Returns:	A pointer to a textual representation of the time.
 *
 * Use:		Converts a time to a textual representation.  Corrupts
 *		@buf_t@.
 */

const char *timestr(time_t t)
{
  struct tm *tm;
  if (!t)
    return ("NEVER");
  tm = localtime(&t);
  strftime((char *)buf_t, sizeof(buf_t), "%Y-%m-%dT%H:%M:%S", tm);
  return ((const char *)buf_t);
}

/* --- @seq_reset@ --- *
 *
 * Arguments:	@seqwin *s@ = sequence-checking window
 *
 * Returns:	---
 *
 * Use:		Resets a sequence number window.
 */

void seq_reset(seqwin *s) { s->seq = 0; s->win = 0; }

/* --- @seq_check@ --- *
 *
 * Arguments:	@seqwin *s@ = sequence-checking window
 *		@uint32 q@ = sequence number to check
 *		@const char *service@ = service to report message from
 *
 * Returns:	Zero on success, nonzero if the sequence number was bad.
 *
 * Use:		Checks a sequence number against the window, updating things
 *		as necessary.
 */

int seq_check(seqwin *s, uint32 q, const char *service)
{
  uint32 qbit;
  uint32 n;

  if (q < s->seq) {
    a_warn(service, "replay", "old-sequence", A_END);
    return (-1);
  }
  if (q >= s->seq + SEQ_WINSZ) {
    n = q - (s->seq + SEQ_WINSZ - 1);
    if (n < SEQ_WINSZ)
      s->win >>= n;
    else
      s->win = 0;
    s->seq += n;
  }
  qbit = 1 << (q - s->seq);
  if (s->win & qbit) {
    a_warn(service, "replay", "duplicated-sequence", A_END);
    return (-1);
  }
  s->win |= qbit;
  return (0);
}

/* --- @versioncmp@ --- *
 *
 * Arguments:	@const char *va, *vb@ = two version strings
 *
 * Returns:	Less than, equal to, or greater than zero, according to
 *		whether @va@ is less than, equal to, or greater than @vb@.
 *
 * Use:		Compares version number strings.
 *
 *		The algorithm is an extension of the Debian version
 *		comparison algorithm.  A version number consists of three
 *		components:
 *
 *		  [EPOCH :] MAIN [- SUB]
 *
 *		The MAIN part may contain colons or hyphens if there is an
 *		EPOCH or SUB, respectively.  Version strings are compared
 *		componentwise: first epochs, then main parts, and finally
 *		subparts.
 *
 *		The component comparison is done as follows.  First, the
 *		initial subsequence of nondigit characters is extracted from
 *		each string, and these are compared lexicographically, using
 *		ASCII ordering, except that letters precede non-letters.  If
 *		both are the same, an initial sequence of digits is extracted
 *		from the remaining parts of the version strings, and these
 *		are compared numerically (an empty sequence being considered
 *		to have the value zero).  This process is repeated until we
 *		have a winner or until both strings are exhausted.
 */

struct vinfo {
  const char *e, *el;
  const char *m, *ml;
  const char *s, *sl;
};

static int vint(const char **vv, const char *vl)
{
  int n = 0;
  const char *v = *vv;
  int ch;

  while (v < vl) {
    ch = *v;
    if (!isdigit((unsigned char)ch))
      break;
    v++;
    n = n * 10 + (ch - '0');
  }
  *vv = v;
  return (n);
}

static const char *vchr(const char **vv, const char *vl)
{
  const char *v = *vv;
  const char *b = v;
  int ch;

  while (v < vl) {
    ch = *v;
    if (isdigit((unsigned char)ch))
      break;
    v++;
  }
  *vv = v;
  return (b);
}

#define CMP(x, y) ((x) < (y) ? -1 : +1)

static int vcmp(const char *va, const char *val,
		const char *vb, const char *vbl)
{
  const char *pa, *pb;
  int ia, ib;

  for (;;) {

    /* --- See if we're done --- */

    if (va == val && vb == vbl)
      return (0);

    /* --- Compare nondigit portions --- */

    pa = vchr(&va, val); pb = vchr(&vb, vbl);
    for (;;) {
      if (pa == va && pb == vb)
	break;
      else if (pa == va)
	return (-1);
      else if (pb == vb)
	return (+1);
      else if (*pa == *pb) {
	pa++; pb++;
	continue;
      } else if (isalpha((unsigned char)*pa) == isalpha((unsigned char)*pb))
	return (CMP(*pa, *pb));
      else if (isalpha((unsigned char)*pa))
	return (-1);
      else
	return (+1);
    }

    /* --- Compare digit portions --- */

    ia = vint(&va, val); ib = vint(&vb, vbl);
    if (ia != ib)
      return (CMP(ia, ib));
  }
}

static void vsplit(const char *v, struct vinfo *vi)
{
  const char *p;
  size_t n;

  if ((p = strchr(v, ':')) == 0)
    vi->e = vi->el = 0;
  else {
    vi->e = v;
    vi->el = p;
    v = p + 1;
  }

  n = strlen(v);
  if ((p = strrchr(v, '-')) == 0)
    vi->s = vi->sl = 0;
  else {    
    vi->s = p + 1;
    vi->sl = v + n;
    n = p - v;
  }

  vi->m = v;
  vi->ml = v + n;
}

int versioncmp(const char *va, const char *vb)
{
  struct vinfo via, vib;
  int rc;

  vsplit(va, &via); vsplit(vb, &vib);
  if ((rc = vcmp(via.e, via.el, vib.e, vib.el)) != 0 ||
      (rc = vcmp(via.m, via.ml, vib.m, vib.ml)) != 0 ||
      (rc = vcmp(via.s, via.sl, vib.s, vib.sl)) != 0)
    return (rc);
  return (0);
}

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