glibc/resolv/ns_name_ntop.c

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/* Convert DNS domain names from network format to textual presentation format.
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1996,1999 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 ISC DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC 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.
*/
#include <arpa/nameser.h>
#include <errno.h>
#include <shlib-compat.h>
#include <stdbool.h>
/* Thinking in noninternationalized US-ASCII (per the DNS spec), is
this character special ("in need of quoting")? */
static inline bool
special (int ch)
{
switch (ch)
{
case '"':
case '.':
case ';':
case '\\':
case '(':
case ')':
/* Special modifiers in zone files. */
case '@':
case '$':
return true;
default:
return false;
}
}
/* Thinking in noninternationalized US-ASCII (per the DNS spec), is
this character visible and not a space when printed? */
static inline bool
printable (int ch)
{
return ch > 0x20 && ch < 0x7f;
}
/* Converts an uncompressed, encoded domain name to printable ASCII as
per RFC1035. Returns the number of bytes written to buffer, or -1
(with errno set). The root is returned as "." All other domains
are returned in non absolute form. */
int
___ns_name_ntop (const unsigned char *src, char *dst, size_t dstsiz)
{
const unsigned char *cp;
char *dn, *eom;
unsigned char c;
int l;
cp = src;
dn = dst;
eom = dst + dstsiz;
while ((l = *cp++) != 0)
{
if (l >= 64)
{
/* Some kind of compression pointer. */
__set_errno (EMSGSIZE);
return -1;
}
if (dn != dst)
{
if (dn >= eom)
{
__set_errno (EMSGSIZE);
return -1;
}
*dn++ = '.';
}
for (; l > 0; l--)
{
c = *cp++;
if (special (c))
{
if (eom - dn < 2)
{
__set_errno (EMSGSIZE);
return -1;
}
*dn++ = '\\';
*dn++ = c;
}
else if (!printable (c))
{
if (eom - dn < 4)
{
__set_errno (EMSGSIZE);
return -1;
}
*dn++ = '\\';
*dn++ = '0' + (c / 100);
*dn++ = '0' + ((c % 100) / 10);
*dn++ = '0' + (c % 10);
}
else
{
if (eom - dn < 2)
{
__set_errno (EMSGSIZE);
return -1;
}
*dn++ = c;
}
}
}
if (dn == dst)
{
if (dn >= eom)
{
__set_errno (EMSGSIZE);
return -1;
}
*dn++ = '.';
}
if (dn >= eom)
{
__set_errno (EMSGSIZE);
return -1;
}
*dn++ = '\0';
return dn - dst;
}
versioned_symbol (libc, ___ns_name_ntop, ns_name_ntop, GLIBC_2_34);
versioned_symbol (libc, ___ns_name_ntop, __ns_name_ntop, GLIBC_PRIVATE);
libc_hidden_ver (___ns_name_ntop, __ns_name_ntop)
#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34)
compat_symbol (libresolv, ___ns_name_ntop, ns_name_ntop, GLIBC_2_9);
#endif