minix/lib/ip/res_comp.c

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2005-04-21 16:53:53 +02:00
/*
* Copyright (c) 1985 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted provided
* that: (1) source distributions retain this entire copyright notice and
* comment, and (2) distributions including binaries display the following
* acknowledgement: ``This product includes software developed by the
* University of California, Berkeley and its contributors'' in the
* documentation or other materials provided with the distribution and in
* all advertising materials mentioning features or use of this software.
* 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)res_comp.c 6.18 (Berkeley) 6/27/90";
#endif /* LIBC_SCCS and not lint */
#if _MINIX
#include <sys/types.h>
#include <stdlib.h>
#include <net/gen/in.h>
#include <net/gen/nameser.h>
#include <net/gen/resolv.h>
static int dn_find _ARGS(( const u_char *exp_dn, const u_char *msg,
u_char **dnptrs, u_char **lastdnptr ));
int dn_skipname _ARGS(( const u_char *comp_dn, const u_char *eom ));
#define getshort _getshort
#define getlong _getlong
#define putshort __putshort
#define putlong __putlong
#else
#include <sys/types.h>
#include <stdio.h>
#include <arpa/nameser.h>
static dn_find();
#endif
#ifdef __STDC__
#define CONST const
#else
#define CONST
#endif
/*
* 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)
CONST u_char *msg, *eomorig, *comp_dn;
u_char *exp_dn;
int length;
{
register CONST u_char *cp;
register u_char *dn;
register int n, c;
CONST u_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++) == '.') {
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 u_char *exp_dn;
u_char *comp_dn;
int length;
u_char **dnptrs, **lastdnptr;
{
register u_char *cp;
register CONST u_char *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) {
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.
*/
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;
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 int
dn_find(exp_dn, msg, dnptrs, lastdnptr)
CONST u_char *exp_dn, *msg;
u_char **dnptrs, **lastdnptr;
{
CONST register u_char *dn, *cp;
register u_char **cpp;
register int n;
CONST 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 (*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.
*/
u16_t
getshort(msgp)
CONST u8_t *msgp;
{
return ((msgp[0] << 8) | (msgp[1] << 0));
}
u32_t
getlong(msgp)
CONST u8_t *msgp;
{
return ( ((u32_t) msgp[0] << 24)
| ((u32_t) msgp[1] << 16)
| ((u32_t) msgp[2] << 8)
| ((u32_t) msgp[3] << 0));
}
void
putshort(s, msgp)
register U16_t s;
register u8_t *msgp;
{
msgp[1] = s;
msgp[0] = s >> 8;
}
void
putlong(l, msgp)
register u32_t l;
register u8_t *msgp;
{
msgp[3] = l;
msgp[2] = (l >>= 8);
msgp[1] = (l >>= 8);
msgp[0] = l >> 8;
}