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/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, you can obtain one at https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
#include <isc/ascii.h>
#include <isc/buffer.h>
#include <isc/result.h>
#include <isc/types.h>
#include <isc/util.h>
#include <dns/compress.h>
#include <dns/types.h>
/*
*/
#include "old.h"
/*
* code copied from lib/dns/name.c as of commit
* 6967973568fe80b03e1729259f8907ce8792be34
*/
typedef enum { fw_start = 0, fw_ordinary, fw_newcurrent } fw_state;
#define VALID_NAME(n) ISC_MAGIC_VALID(n, DNS_NAME_MAGIC)
#define INIT_OFFSETS(name, var, default_offsets) \
if ((name)->offsets != NULL) \
var = (name)->offsets; \
else \
var = (default_offsets);
#define MAKE_EMPTY(name) \
do { \
name->ndata = NULL; \
name->length = 0; \
name->labels = 0; \
name->attributes.absolute = false; \
} while (0)
#define BINDABLE(name) (!name->attributes.readonly && !name->attributes.dynamic)
isc_result_t
old_name_fromwire(dns_name_t *name, isc_buffer_t *source, dns_decompress_t dctx,
unsigned int options, isc_buffer_t *target) {
unsigned char *cdata, *ndata;
unsigned int cused; /* Bytes of compressed name data used */
unsigned int nused, labels, n, nmax;
unsigned int current, new_current, biggest_pointer;
bool done;
fw_state state = fw_start;
unsigned int c;
unsigned char *offsets;
dns_offsets_t odata;
bool downcase;
bool seen_pointer;
/*
* Copy the possibly-compressed name at source into target,
* decompressing it. Loop prevention is performed by checking
* the new pointer against biggest_pointer.
*/
REQUIRE(VALID_NAME(name));
REQUIRE((target != NULL && ISC_BUFFER_VALID(target)) ||
(target == NULL && ISC_BUFFER_VALID(name->buffer)));
downcase = ((options & DNS_NAME_DOWNCASE) != 0);
if (target == NULL && name->buffer != NULL) {
target = name->buffer;
isc_buffer_clear(target);
}
REQUIRE(BINDABLE(name));
INIT_OFFSETS(name, offsets, odata);
/*
* Make 'name' empty in case of failure.
*/
MAKE_EMPTY(name);
/*
* Initialize things to make the compiler happy; they're not required.
*/
n = 0;
new_current = 0;
/*
* Set up.
*/
labels = 0;
done = false;
ndata = isc_buffer_used(target);
nused = 0;
seen_pointer = false;
/*
* Find the maximum number of uncompressed target name
* bytes we are willing to generate. This is the smaller
* of the available target buffer length and the
* maximum legal domain name length (255).
*/
nmax = isc_buffer_availablelength(target);
if (nmax > DNS_NAME_MAXWIRE) {
nmax = DNS_NAME_MAXWIRE;
}
cdata = isc_buffer_current(source);
cused = 0;
current = source->current;
biggest_pointer = current;
/*
* Note: The following code is not optimized for speed, but
* rather for correctness. Speed will be addressed in the future.
*/
while (current < source->active && !done) {
c = *cdata++;
current++;
if (!seen_pointer) {
cused++;
}
switch (state) {
case fw_start:
if (c < 64) {
offsets[labels] = nused;
labels++;
if (nused + c + 1 > nmax) {
goto full;
}
nused += c + 1;
*ndata++ = c;
if (c == 0) {
done = true;
}
n = c;
state = fw_ordinary;
} else if (c >= 192) {
/*
* 14-bit compression pointer
*/
if (!dns_decompress_getpermitted(dctx)) {
return DNS_R_DISALLOWED;
}
new_current = c & 0x3F;
state = fw_newcurrent;
} else {
return DNS_R_BADLABELTYPE;
}
break;
case fw_ordinary:
if (downcase) {
c = isc_ascii_tolower(c);
}
*ndata++ = c;
n--;
if (n == 0) {
state = fw_start;
}
break;
case fw_newcurrent:
new_current *= 256;
new_current += c;
if (new_current >= biggest_pointer) {
return DNS_R_BADPOINTER;
}
biggest_pointer = new_current;
current = new_current;
cdata = (unsigned char *)source->base + current;
seen_pointer = true;
state = fw_start;
break;
default:
FATAL_ERROR("Unknown state %d", state);
/* Does not return. */
}
}
if (!done) {
return ISC_R_UNEXPECTEDEND;
}
name->ndata = (unsigned char *)target->base + target->used;
name->labels = labels;
name->length = nused;
name->attributes.absolute = true;
isc_buffer_forward(source, cused);
isc_buffer_add(target, name->length);
return ISC_R_SUCCESS;
full:
if (nmax == DNS_NAME_MAXWIRE) {
/*
* The name did not fit even though we had a buffer
* big enough to fit a maximum-length name.
*/
return DNS_R_NAMETOOLONG;
} else {
/*
* The name might fit if only the caller could give us a
* big enough buffer.
*/
return ISC_R_NOSPACE;
}
}
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