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res_comp.c

/*
 * ++Copyright++ 1985, 1993
 * -
 * Copyright (c) 1985, 1993
 *    The Regents of the University of California.  All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * -
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 * 
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 * -
 * --Copyright--
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_comp.c    8.1 (Berkeley) 6/4/93";
static char rcsid[] = "$Id: res_comp.c,v 1.1.1.1 1998/02/10 21:01:47 mea Exp $";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/param.h>
#include <netinet/in.h>
#include "arpa/nameser.h"

#include <stdio.h>
#include "resolv.h"
#include <ctype.h>

#if defined(BSD) && (BSD >= 199103)
# include <unistd.h>
# include <string.h>
#else
# include "portability.h"
#endif

static int  dn_find __P((u_char *exp_dn, u_char *msg,
                       u_char **dnptrs, u_char **lastdnptr));

/*
 * Expand compressed domain name 'comp_dn' to full domain name.
 * 'msg' is a pointer to the begining of the message,
 * 'eomorig' points to the first location after the message,
 * 'exp_dn' is a pointer to a buffer of size 'length' for the result.
 * Return size of compressed name or -1 if there was an error.
 */
int
dn_expand(msg, eomorig, comp_dn, exp_dn, length)
      const u_char *msg, *eomorig, *comp_dn;
      char *exp_dn;
      int length;
{
      register const u_char *cp;
      register char *dn;
      register int n, c;
      char *eom;
      int len = -1, checked = 0;

      dn = exp_dn;
      cp = comp_dn;
      eom = exp_dn + length;
      /*
       * fetch next label in domain name
       */
      while (n = *cp++) {
            /*
             * Check for indirection
             */
            switch (n & INDIR_MASK) {
            case 0:
                  if (dn != exp_dn) {
                        if (dn >= eom)
                              return (-1);
                        *dn++ = '.';
                  }
                  if (dn+n >= eom)
                        return (-1);
                  checked += n + 1;
                  while (--n >= 0) {
                        if (((c = *cp++) == '.') || (c == '\\')) {
                              if (dn + n + 2 >= eom)
                                    return (-1);
                              *dn++ = '\\';
                        }
                        *dn++ = c;
                        if (cp >= eomorig)      /* out of range */
                              return (-1);
                  }
                  break;

            case INDIR_MASK:
                  if (len < 0)
                        len = cp - comp_dn + 1;
                  cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff));
                  if (cp < msg || cp >= eomorig)      /* out of range */
                        return (-1);
                  checked += 2;
                  /*
                   * Check for loops in the compressed name;
                   * if we've looked at the whole message,
                   * there must be a loop.
                   */
                  if (checked >= eomorig - msg)
                        return (-1);
                  break;

            default:
                  return (-1);                  /* flag error */
            }
      }
      *dn = '\0';
      if (len < 0)
            len = cp - comp_dn;
      return (len);
}

/*
 * Compress domain name 'exp_dn' into 'comp_dn'.
 * Return the size of the compressed name or -1.
 * 'length' is the size of the array pointed to by 'comp_dn'.
 * 'dnptrs' is a list of pointers to previous compressed names. dnptrs[0]
 * is a pointer to the beginning of the message. The list ends with NULL.
 * 'lastdnptr' is a pointer to the end of the arrary pointed to
 * by 'dnptrs'. Side effect is to update the list of pointers for
 * labels inserted into the message as we compress the name.
 * If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
 * is NULL, we don't update the list.
 */
int
dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr)
      const char *exp_dn;
      u_char *comp_dn, **dnptrs, **lastdnptr;
      int length;
{
      register u_char *cp, *dn;
      register int c, l;
      u_char **cpp, **lpp, *sp, *eob;
      u_char *msg;

      dn = (u_char *)exp_dn;
      cp = comp_dn;
      eob = cp + length;
      lpp = cpp = NULL;
      if (dnptrs != NULL) {
            if ((msg = *dnptrs++) != NULL) {
                  for (cpp = dnptrs; *cpp != NULL; cpp++)
                        ;
                  lpp = cpp;  /* end of list to search */
            }
      } else
            msg = NULL;
      for (c = *dn++; c != '\0'; ) {
            /* look to see if we can use pointers */
            if (msg != NULL) {
                  if ((l = dn_find(dn-1, msg, dnptrs, lpp)) >= 0) {
                        if (cp+1 >= eob)
                              return (-1);
                        *cp++ = (l >> 8) | INDIR_MASK;
                        *cp++ = l % 256;
                        return (cp - comp_dn);
                  }
                  /* not found, save it */
                  if (lastdnptr != NULL && cpp < lastdnptr-1) {
                        *cpp++ = cp;
                        *cpp = NULL;
                  }
            }
            sp = cp++;  /* save ptr to length byte */
            do {
                  if (c == '.') {
                        c = *dn++;
                        break;
                  }
                  if (c == '\\') {
                        if ((c = *dn++) == '\0')
                              break;
                  }
                  if (cp >= eob) {
                        if (msg != NULL)
                              *lpp = NULL;
                        return (-1);
                  }
                  *cp++ = c;
            } while ((c = *dn++) != '\0');
            /* catch trailing '.'s but not '..' */
            if ((l = cp - sp - 1) == 0 && c == '\0') {
                  cp--;
                  break;
            }
            if (l <= 0 || l > MAXLABEL) {
                  if (msg != NULL)
                        *lpp = NULL;
                  return (-1);
            }
            *sp = l;
      }
      if (cp >= eob) {
            if (msg != NULL)
                  *lpp = NULL;
            return (-1);
      }
      *cp++ = '\0';
      return (cp - comp_dn);
}

/*
 * Skip over a compressed domain name. Return the size or -1.
 */
int
__dn_skipname(comp_dn, eom)
      const u_char *comp_dn, *eom;
{
      register const u_char *cp;
      register int n;

      cp = comp_dn;
      while (cp < eom && (n = *cp++)) {
            /*
             * check for indirection
             */
            switch (n & INDIR_MASK) {
            case 0:                 /* normal case, n == len */
                  cp += n;
                  continue;
            case INDIR_MASK:  /* indirection */
                  cp++;
                  break;
            default:          /* illegal type */
                  return (-1);
            }
            break;
      }
      if (cp > eom)
            return (-1);
      return (cp - comp_dn);
}

static int
mklower(ch)
      register int ch;
{
      if (isascii(ch) && isupper(ch))
            return (tolower(ch));
      return (ch);
}

/*
 * Search for expanded name from a list of previously compressed names.
 * Return the offset from msg if found or -1.
 * dnptrs is the pointer to the first name on the list,
 * not the pointer to the start of the message.
 */
static int
dn_find(exp_dn, msg, dnptrs, lastdnptr)
      u_char *exp_dn, *msg;
      u_char **dnptrs, **lastdnptr;
{
      register u_char *dn, *cp, **cpp;
      register int n;
      u_char *sp;

      for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
            dn = exp_dn;
            sp = cp = *cpp;
            while (n = *cp++) {
                  /*
                   * check for indirection
                   */
                  switch (n & INDIR_MASK) {
                  case 0:           /* normal case, n == len */
                        while (--n >= 0) {
                              if (*dn == '.')
                                    goto next;
                              if (*dn == '\\')
                                    dn++;
                              if (mklower(*dn++) != mklower(*cp++))
                                    goto next;
                        }
                        if ((n = *dn++) == '\0' && *cp == '\0')
                              return (sp - msg);
                        if (n == '.')
                              continue;
                        goto next;

                  case INDIR_MASK:  /* indirection */
                        cp = msg + (((n & 0x3f) << 8) | *cp);
                        break;

                  default:    /* illegal type */
                        return (-1);
                  }
            }
            if (*dn == '\0')
                  return (sp - msg);
      next: ;
      }
      return (-1);
}

/*
 * Verify that a domain name uses an acceptable character set.
 */

/****
To: "Lawrence R. Rogers" <lrr@cert.org>
cc: cert@cert.org, pvm@home.net
Subject: Re: VU#14542 
In-reply-to: Your message of "Mon, 19 Feb 1996 17:16:27 PST."
Date: Tue, 20 Feb 1996 22:37:21 -0800
From: Paul A Vixie <vixie@wisdom.home.vix.com>

in retrospect,

      hostname = firstlabel ( "." otherlabel )+
      firstchar = [a-zA-Z0-9_]
      otherchar = [a-zA-Z0-9_-/]
      firstlabel = firstchar otherchar*
      otherlabel = otherchar+

should have been

      hostname = label ( "." label )+
      firstchar = [a-zA-Z0-9]
      otherchar = [a-zA-Z0-9_-]
      label = firstchar otherchar*

i know of no example of a real host name that needs the looser rule i sent
earlier.  since i'm only trying to bend the spec to fit actual known uses,
i should not have widened the rules as far as i did earlier.
****/

/*
 * Note the conspicuous absence of ctype macros in these definitions.  On
 * non-ASCII hosts, we can't depend on string literals or ctype macros to
 * tell us anything about network-format data.  The rest of the BIND system
 * is not careful about this, but for some reason, we're doing it right here.
 */
#define PERIOD 0x2e
#define     hyphenchar(c) ((c) == 0x2d)
#define bslashchar(c) ((c) == 0x5c)
#define periodchar(c) ((c) == PERIOD)
#define asterchar(c) ((c) == 0x2a)
#define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) \
               || ((c) >= 0x61 && (c) <= 0x7a))
#define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)

#define borderchar(c) (alphachar(c) || digitchar(c))
#define middlechar(c) (borderchar(c) || hyphenchar(c))
#define     domainchar(c) ((c) > 0x20 && (c) < 0x7f)

int
res_hnok(dn)
      const char *dn;
{
      int ppch = '\0', pch = PERIOD, ch = *dn++;

      while (ch != '\0') {
            int nch = *dn++;

            if (periodchar(ch)) {
                  NULL;
            } else if (periodchar(pch)) {
                  if (!borderchar(ch))
                        return (0);
            } else if (periodchar(nch) || nch == '\0') {
                  if (!borderchar(ch))
                        return (0);
            } else {
                  if (!middlechar(ch))
                        return (0);
            }
            ppch = pch, pch = ch, ch = nch;
      }
      return (1);
}

/*
 * hostname-like (A, MX, WKS) owners can have "*" as their first label
 * but must otherwise be as a host name.
 */
int
res_ownok(dn)
      const char *dn;
{
      if (asterchar(dn[0]) && periodchar(dn[1]))
            dn += 2;
      return (res_hnok(dn));
}

/*
 * SOA RNAMEs and RP RNAMEs can have any printable character in their first
 * label, but the rest of the name has to look like a host name.
 */
int
res_mailok(dn)
      const char *dn;
{
      int ch, pch;

      pch = '\0';
      while ((ch = *dn++) != '\0') {
            if (!domainchar(ch))
                  return (0);
            if (periodchar(ch) && !bslashchar(pch))
                  break;
            pch = ch;
      }
      return (res_hnok(dn));
}

/*
 * This function is quite liberal, since RFC 1034's character sets are only
 * recommendations.
 */
int
res_dnok(dn)
      const char *dn;
{
      int ch;

      while ((ch = *dn++) != '\0')
            if (!domainchar(ch))
                  return (0);
      return (1);
}

/*
 * Routines to insert/extract short/long's.
 */

u_int16_t
_getshort(msgp)
      register const u_char *msgp;
{
      register u_int16_t u;

      GETSHORT(u, msgp);
      return (u);
}

#ifdef NeXT
/*
 * nExt machines have some funky library conventions, which we must maintain.
 */
u_int16_t
res_getshort(msgp)
      register const u_char *msgp;
{
      return (_getshort(msgp));
}
#endif

u_int32_t
_getlong(msgp)
      register const u_char *msgp;
{
      register u_int32_t u;

      GETLONG(u, msgp);
      return (u);
}

void
#if defined(__STDC__) || defined(__cplusplus)
__putshort(register u_int16_t s, register u_char *msgp)     /* must match proto */
#else
__putshort(s, msgp)
      register u_int16_t s;
      register u_char *msgp;
#endif
{
      PUTSHORT(s, msgp);
}

void
__putlong(l, msgp)
      register u_int32_t l;
      register u_char *msgp;
{
      PUTLONG(l, msgp);
}

#ifdef ultrix
/* ultrix 4.0 had some icky packaging in its libc.a.  alias for it here.
 * there is more gunk of this kind over in res_debug.c.
 */
#undef putshort
void
#if defined(__STDC__) || defined(__cplusplus)
putshort(register u_short s, register u_char *msgp)
#else
putshort(s, msgp)
      register u_short s;
      register u_char *msgp;
#endif
{
      __putshort(s, msgp);
}
#undef putlong
void
putlong(l, msgp)
      register u_int32_t l;
      register u_char *msgp;
{
      __putlong(l, msgp);
}
 
#undef dn_skipname
dn_skipname(comp_dn, eom)
      const u_char *comp_dn, *eom;
{
      return (__dn_skipname(comp_dn, eom));
}
#endif /* Ultrix 4.0 hackery */

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