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/* Skip over an uncompressed name in wire format.
Copyright (C) 2022-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <arpa/nameser.h>
#include <errno.h>
#include <stdbool.h>
int
__ns_name_length_uncompressed (const unsigned char *p,
const unsigned char *eom)
{
const unsigned char *start = p;
while (true)
{
if (p == eom)
{
/* Truncated packet: no room for label length. */
__set_errno (EMSGSIZE);
return -1;
}
unsigned char b = *p;
++p;
if (b == 0)
{
/* Root label. */
size_t length = p - start;
if (length > NS_MAXCDNAME)
{
/* Domain name too long. */
__set_errno (EMSGSIZE);
return -1;
}
return length;
}
if (b <= 63)
{
/* Regular label. */
if (b <= eom - p)
p += b;
else
{
/* Truncated packet: label incomplete. */
__set_errno (EMSGSIZE);
return -1;
}
}
else
{
/* Compression reference or corrupted label length. */
__set_errno (EMSGSIZE);
return -1;
}
}
}
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