* Copyright (c) 1985 Regents of the University of California.
* 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) %G%";
#endif /* LIBC_SCCS and not lint */
#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
;
register u_char
*cp
, *dn
;
int len
= -1, checked
= 0;
eom
= exp_dn
+ length
- 1;
* fetch next label in domain name
switch (n
& INDIR_MASK
) {
if ((c
= *cp
++) == '.') {
if (cp
>= eomorig
) /* out of range */
cp
= msg
+ (((n
& 0x3f) << 8) | (*cp
& 0xff));
if (cp
< msg
|| cp
>= eomorig
) /* out of range */
* Check for loops in the compressed name;
* if we've looked at the whole message,
if (checked
>= eomorig
- msg
)
return (-1); /* flag error */
* 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
;
u_char
**dnptrs
, **lastdnptr
;
register u_char
*cp
, *dn
;
u_char
**cpp
, **lpp
, *sp
, *eob
;
if ((msg
= *dnptrs
++) != NULL
) {
for (cpp
= dnptrs
; *cpp
!= NULL
; cpp
++)
lpp
= cpp
; /* end of list to search */
for (c
= *dn
++; c
!= '\0'; ) {
/* look to see if we can use pointers */
if ((l
= dn_find(dn
-1, msg
, dnptrs
, lpp
)) >= 0) {
*cp
++ = (l
>> 8) | INDIR_MASK
;
if (lastdnptr
!= NULL
&& cpp
< lastdnptr
-1) {
sp
= cp
++; /* save ptr to length byte */
} while ((c
= *dn
++) != '\0');
/* catch trailing '.'s but not '..' */
if ((l
= cp
- sp
- 1) == 0 && c
== '\0') {
if (l
<= 0 || l
> MAXLABEL
)
* Skip over a compressed domain name. Return the size or -1.
dn_skipname(comp_dn
, eom
)
while (cp
< eom
&& (n
= *cp
++)) {
switch (n
& INDIR_MASK
) {
case 0: /* normal case, n == len */
default: /* illegal type */
case INDIR_MASK
: /* indirection */
* 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.
dn_find(exp_dn
, msg
, dnptrs
, lastdnptr
)
u_char
**dnptrs
, **lastdnptr
;
register u_char
*dn
, *cp
, **cpp
;
for (cpp
= dnptrs
; cpp
< lastdnptr
; cpp
++) {
switch (n
& INDIR_MASK
) {
case 0: /* normal case, n == len */
if ((n
= *dn
++) == '\0' && *cp
== '\0')
default: /* illegal type */
case INDIR_MASK
: /* indirection */
cp
= msg
+ (((n
& 0x3f) << 8) | *cp
);
* 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.
register u_char
*p
= (u_char
*) msgp
;
* vax compiler doesn't put shorts in registers
return ((u_short
)(u
| *p
));
register u_char
*p
= (u_char
*) msgp
;