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freebsd/lib/libc/net/ns_name.c
Peter Wemm 7f3dea244c $Id$ -> $FreeBSD$
1999-08-28 00:22:10 +00:00

594 lines
13 KiB
C
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/*
* Copyright (c) 1996 by Internet Software Consortium.
*
* 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.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM 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.
*/
#ifndef lint
static char rcsid[] = "$FreeBSD$";
#endif
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <errno.h>
#include <resolv.h>
#include <string.h>
/* Data. */
static char digits[] = "0123456789";
/* Forward. */
static int special(int);
static int printable(int);
static int dn_find(const u_char *, const u_char *,
const u_char * const *,
const u_char * const *);
/* Public. */
/*
* ns_name_ntop(src, dst, dstsiz)
* Convert an encoded domain name to printable ascii as per RFC1035.
* return:
* Number of bytes written to buffer, or -1 (with errno set)
* notes:
* The root is returned as "."
* All other domains are returned in non absolute form
*/
int
ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) {
const u_char *cp;
char *dn, *eom;
u_char c;
u_int n;
cp = src;
dn = dst;
eom = dst + dstsiz;
while ((n = *cp++) != 0) {
if ((n & NS_CMPRSFLGS) != 0) {
/* Some kind of compression pointer. */
errno = EMSGSIZE;
return (-1);
}
if (dn != dst) {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '.';
}
if (dn + n >= eom) {
errno = EMSGSIZE;
return (-1);
}
for ((void)NULL; n > 0; n--) {
c = *cp++;
if (special(c)) {
if (dn + 1 >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\\';
*dn++ = (char)c;
} else if (!printable(c)) {
if (dn + 3 >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\\';
*dn++ = digits[c / 100];
*dn++ = digits[(c % 100) / 10];
*dn++ = digits[c % 10];
} else {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = (char)c;
}
}
}
if (dn == dst) {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '.';
}
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\0';
return (dn - dst);
}
/*
* ns_name_pton(src, dst, dstsiz)
* Convert a ascii string into an encoded domain name as per RFC1035.
* return:
* -1 if it fails
* 1 if string was fully qualified
* 0 is string was not fully qualified
* notes:
* Enforces label and domain length limits.
*/
int
ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
u_char *label, *bp, *eom;
int c, n, escaped;
char *cp;
escaped = 0;
bp = dst;
eom = dst + dstsiz;
label = bp++;
while ((c = *src++) != 0) {
if (escaped) {
if ((cp = strchr(digits, c)) != NULL) {
n = (cp - digits) * 100;
if ((c = *src++) == 0 ||
(cp = strchr(digits, c)) == NULL) {
errno = EMSGSIZE;
return (-1);
}
n += (cp - digits) * 10;
if ((c = *src++) == 0 ||
(cp = strchr(digits, c)) == NULL) {
errno = EMSGSIZE;
return (-1);
}
n += (cp - digits);
if (n > 255) {
errno = EMSGSIZE;
return (-1);
}
c = n;
}
escaped = 0;
} else if (c == '\\') {
escaped = 1;
continue;
} else if (c == '.') {
c = (bp - label - 1);
if ((c & NS_CMPRSFLGS) != 0) { /* Label too big. */
errno = EMSGSIZE;
return (-1);
}
if (label >= eom) {
errno = EMSGSIZE;
return (-1);
}
*label = c;
/* Fully qualified ? */
if (*src == '\0') {
if (c != 0) {
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = '\0';
}
if ((bp - dst) > MAXCDNAME) {
errno = EMSGSIZE;
return (-1);
}
return (1);
}
if (c == 0) {
errno = EMSGSIZE;
return (-1);
}
label = bp++;
continue;
}
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = (u_char)c;
}
c = (bp - label - 1);
if ((c & NS_CMPRSFLGS) != 0) { /* Label too big. */
errno = EMSGSIZE;
return (-1);
}
if (label >= eom) {
errno = EMSGSIZE;
return (-1);
}
*label = c;
if (c != 0) {
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = 0;
}
if ((bp - dst) > MAXCDNAME) { /* src too big */
errno = EMSGSIZE;
return (-1);
}
return (0);
}
/*
* ns_name_unpack(msg, eom, src, dst, dstsiz)
* Unpack a domain name from a message, source may be compressed.
* return:
* -1 if it fails, or consumed octets if it succeeds.
*/
int
ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
u_char *dst, size_t dstsiz)
{
const u_char *srcp, *dstlim;
u_char *dstp;
int n, c, len, checked;
len = -1;
checked = 0;
dstp = dst;
srcp = src;
dstlim = dst + dstsiz;
if (srcp < msg || srcp >= eom) {
errno = EMSGSIZE;
return (-1);
}
/* Fetch next label in domain name. */
while ((n = *srcp++) != 0) {
/* Check for indirection. */
switch (n & NS_CMPRSFLGS) {
case 0:
/* Limit checks. */
if (dstp + n + 1 >= dstlim || srcp + n >= eom) {
errno = EMSGSIZE;
return (-1);
}
checked += n + 1;
*dstp++ = n;
memcpy(dstp, srcp, n);
dstp += n;
srcp += n;
break;
case NS_CMPRSFLGS:
if (srcp >= eom) {
errno = EMSGSIZE;
return (-1);
}
if (len < 0)
len = srcp - src + 1;
srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
if (srcp < msg || srcp >= eom) { /* Out of range. */
errno = EMSGSIZE;
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 >= eom - msg) {
errno = EMSGSIZE;
return (-1);
}
break;
default:
errno = EMSGSIZE;
return (-1); /* flag error */
}
}
*dstp = '\0';
if (len < 0)
len = srcp - src;
return (len);
}
/*
* ns_name_pack(src, dst, dstsiz, dnptrs, lastdnptr)
* Pack domain name 'domain' into 'comp_dn'.
* return:
* Size of the compressed name, or -1.
* notes:
* 'dnptrs' is an array of pointers to previous compressed names.
* dnptrs[0] is a pointer to the beginning of the message. The array
* ends with NULL.
* 'lastdnptr' is a pointer to the end of the array pointed to
* by 'dnptrs'.
* Side effects:
* The list of pointers in dnptrs is updated 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
ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
const u_char **dnptrs, const u_char **lastdnptr)
{
u_char *dstp;
const u_char **cpp, **lpp, *eob, *msg;
const u_char *srcp;
int n, l;
srcp = src;
dstp = dst;
eob = dstp + dstsiz;
lpp = cpp = NULL;
if (dnptrs != NULL) {
if ((msg = *dnptrs++) != NULL) {
for (cpp = dnptrs; *cpp != NULL; cpp++)
(void)NULL;
lpp = cpp; /* end of list to search */
}
} else
msg = NULL;
/* make sure the domain we are about to add is legal */
l = 0;
do {
n = *srcp;
if ((n & NS_CMPRSFLGS) != 0) {
errno = EMSGSIZE;
return (-1);
}
l += n + 1;
if (l > MAXCDNAME) {
errno = EMSGSIZE;
return (-1);
}
srcp += n + 1;
} while (n != 0);
srcp = src;
do {
/* Look to see if we can use pointers. */
n = *srcp;
if (n != 0 && msg != NULL) {
l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
(const u_char * const *)lpp);
if (l >= 0) {
if (dstp + 1 >= eob) {
errno = EMSGSIZE;
return (-1);
}
*dstp++ = (l >> 8) | NS_CMPRSFLGS;
*dstp++ = l % 256;
return (dstp - dst);
}
/* Not found, save it. */
if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
(dstp - msg) < 0x4000) {
*cpp++ = dstp;
*cpp = NULL;
}
}
/* copy label to buffer */
if (n & NS_CMPRSFLGS) { /* Should not happen. */
errno = EMSGSIZE;
return (-1);
}
if (dstp + 1 + n >= eob) {
errno = EMSGSIZE;
return (-1);
}
memcpy(dstp, srcp, n + 1);
srcp += n + 1;
dstp += n + 1;
} while (n != 0);
if (dstp > eob) {
if (msg != NULL)
*lpp = NULL;
errno = EMSGSIZE;
return (-1);
}
return (dstp - dst);
}
/*
* ns_name_uncompress(msg, eom, src, dst, dstsiz)
* Expand compressed domain name to presentation format.
* return:
* Number of bytes read out of `src', or -1 (with errno set).
* note:
* Root domain returns as "." not "".
*/
int
ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
char *dst, size_t dstsiz)
{
u_char tmp[NS_MAXCDNAME];
int n;
if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
return (-1);
if (ns_name_ntop(tmp, dst, dstsiz) == -1)
return (-1);
return (n);
}
/*
* ns_name_compress(src, dst, dstsiz, dnptrs, lastdnptr)
* Compress a domain name into wire format, using compression pointers.
* return:
* Number of bytes consumed in `dst' or -1 (with errno set).
* notes:
* 'dnptrs' is an array 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
* array 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
ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
const u_char **dnptrs, const u_char **lastdnptr)
{
u_char tmp[NS_MAXCDNAME];
if (ns_name_pton(src, tmp, sizeof tmp) == -1)
return (-1);
return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
}
/*
* ns_name_skip(ptrptr, eom)
* Advance *ptrptr to skip over the compressed name it points at.
* return:
* 0 on success, -1 (with errno set) on failure.
*/
int
ns_name_skip(const u_char **ptrptr, const u_char *eom) {
const u_char *cp;
u_int n;
cp = *ptrptr;
while (cp < eom && (n = *cp++) != 0) {
/* Check for indirection. */
switch (n & NS_CMPRSFLGS) {
case 0: /* normal case, n == len */
cp += n;
continue;
case NS_CMPRSFLGS: /* indirection */
cp++;
break;
default: /* illegal type */
errno = EMSGSIZE;
return (-1);
}
break;
}
if (cp > eom) {
errno = EMSGSIZE;
return (-1);
}
*ptrptr = cp;
return (0);
}
/* Private. */
/*
* special(ch)
* Thinking in noninternationalized USASCII (per the DNS spec),
* is this characted special ("in need of quoting") ?
* return:
* boolean.
*/
static int
special(int ch) {
switch (ch) {
case 0x22: /* '"' */
case 0x2E: /* '.' */
case 0x3B: /* ';' */
case 0x5C: /* '\\' */
/* Special modifiers in zone files. */
case 0x40: /* '@' */
case 0x24: /* '$' */
return (1);
default:
return (0);
}
}
/*
* printable(ch)
* Thinking in noninternationalized USASCII (per the DNS spec),
* is this character visible and not a space when printed ?
* return:
* boolean.
*/
static int
printable(int ch) {
return (ch > 0x20 && ch < 0x7f);
}
/*
* Thinking in noninternationalized USASCII (per the DNS spec),
* convert this character to lower case if it's upper case.
*/
static int
mklower(int ch) {
if (ch >= 0x41 && ch <= 0x5A)
return (ch + 0x20);
return (ch);
}
/*
* dn_find(domain, msg, dnptrs, lastdnptr)
* Search for the counted-label name in an array of compressed names.
* return:
* offset from msg if found, or -1.
* notes:
* dnptrs is the pointer to the first name on the list,
* not the pointer to the start of the message.
*/
static int
dn_find(const u_char *domain, const u_char *msg,
const u_char * const *dnptrs,
const u_char * const *lastdnptr)
{
const u_char *dn, *cp, *sp;
const u_char * const *cpp;
u_int n;
for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
dn = domain;
sp = cp = *cpp;
while ((n = *cp++) != 0) {
/*
* check for indirection
*/
switch (n & NS_CMPRSFLGS) {
case 0: /* normal case, n == len */
if (n != *dn++)
goto next;
for ((void)NULL; n > 0; n--)
if (mklower(*dn++) != mklower(*cp++))
goto next;
/* Is next root for both ? */
if (*dn == '\0' && *cp == '\0')
return (sp - msg);
if (*dn)
continue;
goto next;
case NS_CMPRSFLGS: /* indirection */
cp = msg + (((n & 0x3f) << 8) | *cp);
break;
default: /* illegal type */
errno = EMSGSIZE;
return (-1);
}
}
next: ;
}
errno = ENOENT;
return (-1);
}
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