BSD 4_3_Tahoe release

[unix-history] / usr / src / lib / libc / net / res_comp.c

/*
* Copyright (c) 1985 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_comp.c  6.14 (Berkeley) 6/27/88";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <stdio.h>
#include <arpa/nameser.h>

/*
* 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.
*/
dn_expand(msg, eomorig, comp_dn, exp_dn, length)
       u_char *msg, *eomorig, *comp_dn, *exp_dn;
       int length;
{
       register u_char *cp, *dn;
       register int n, c;
       u_char *eom;
       int len = -1, checked = 0;

       dn = exp_dn;
       cp = comp_dn;
       eom = exp_dn + length - 1;
       /*
        * 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++) == '.') {
                                       if (dn+n+1 >= 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.
*/
dn_comp(exp_dn, comp_dn, length, dnptrs, lastdnptr)
       u_char *exp_dn, *comp_dn;
       int length;
       u_char **dnptrs, **lastdnptr;
{
       register u_char *cp, *dn;
       register int c, l;
       u_char **cpp, **lpp, *sp, *eob;
       u_char *msg;

       dn = exp_dn;
       cp = comp_dn;
       eob = cp + length;
       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)
                               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)
                       return (-1);
               *sp = l;
       }
       if (cp >= eob)
               return (-1);
       *cp++ = '\0';
       return (cp - comp_dn);
}

/*
* Skip over a compressed domain name. Return the size or -1.
*/
dn_skipname(comp_dn, eom)
       u_char *comp_dn, *eom;
{
       register 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;
               default:        /* illegal type */
                       return (-1);
               case INDIR_MASK:        /* indirection */
                       cp++;
               }
               break;
       }
       return (cp - comp_dn);
}

/*
* 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
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 == '\\')
                                               dn++;
                                       if (*dn++ != *cp++)
                                               goto next;
                               }
                               if ((n = *dn++) == '\0' && *cp == '\0')
                                       return (sp - msg);
                               if (n == '.')
                                       continue;
                               goto next;

                       default:        /* illegal type */
                               return (-1);

                       case INDIR_MASK:        /* indirection */
                               cp = msg + (((n & 0x3f) << 8) | *cp);
                       }
               }
               if (*dn == '\0')
                       return (sp - msg);
       next:   ;
       }
       return (-1);
}

/*
* Routines to insert/extract short/long's. Must account for byte
* order and non-alignment problems. This code at least has the
* advantage of being portable.
*
* used by sendmail.
*/

u_short
_getshort(msgp)
       u_char *msgp;
{
       register u_char *p = (u_char *) msgp;
#ifdef vax
       /*
        * vax compiler doesn't put shorts in registers
        */
       register u_long u;
#else
       register u_short u;
#endif

       u = *p++ << 8;
       return ((u_short)(u | *p));
}

u_long
_getlong(msgp)
       u_char *msgp;
{
       register u_char *p = (u_char *) msgp;
       register u_long u;

       u = *p++; u <<= 8;
       u |= *p++; u <<= 8;
       u |= *p++; u <<= 8;
       return (u | *p);
}


putshort(s, msgp)
       register u_short s;
       register u_char *msgp;
{

       msgp[1] = s;
       msgp[0] = s >> 8;
}

putlong(l, msgp)
       register u_long l;
       register u_char *msgp;
{

       msgp[3] = l;
       msgp[2] = (l >>= 8);
       msgp[1] = (l >>= 8);
       msgp[0] = l >> 8;
}