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15748c325c
When pulling for example an RRSIG record, we end up with length!=0 *and* unexpected.length != 0, but with an unknown rrec. We should be able to marshall what we retrieved from the wire. Signed-off-by: Volker Lendecke <vl@samba.org> Reviewed-by: Jeremy Allison <jra@samba.org>
396 lines
11 KiB
C
396 lines
11 KiB
C
/*
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Unix SMB/CIFS implementation.
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manipulate dns name structures
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Copyright (C) 2010 Kai Blin <kai@samba.org>
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Heavily based on nbtname.c which is:
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Copyright (C) Andrew Tridgell 2005
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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see rfc1002 for the detailed format of compressed names
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*/
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#include "includes.h"
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#include "librpc/gen_ndr/ndr_dns.h"
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#include "librpc/gen_ndr/ndr_misc.h"
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#include "librpc/gen_ndr/ndr_dnsp.h"
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#include "system/locale.h"
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#include "lib/util/util_net.h"
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/* don't allow an unlimited number of name components */
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#define MAX_COMPONENTS 128
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/**
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print a dns string
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*/
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_PUBLIC_ void ndr_print_dns_string(struct ndr_print *ndr,
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const char *name,
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const char *s)
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{
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ndr_print_string(ndr, name, s);
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}
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/*
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pull one component of a dns_string
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*/
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static enum ndr_err_code ndr_pull_component(struct ndr_pull *ndr,
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uint8_t **component,
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uint32_t *offset,
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uint32_t *max_offset)
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{
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uint8_t len;
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unsigned int loops = 0;
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while (loops < 5) {
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if (*offset >= ndr->data_size) {
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return ndr_pull_error(ndr, NDR_ERR_STRING,
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"BAD DNS NAME component, bad offset");
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}
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len = ndr->data[*offset];
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if (len == 0) {
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*offset += 1;
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*max_offset = MAX(*max_offset, *offset);
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*component = NULL;
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return NDR_ERR_SUCCESS;
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}
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if ((len & 0xC0) == 0xC0) {
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/* its a label pointer */
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if (1 + *offset >= ndr->data_size) {
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return ndr_pull_error(ndr, NDR_ERR_STRING,
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"BAD DNS NAME component, " \
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"bad label offset");
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}
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*max_offset = MAX(*max_offset, *offset + 2);
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*offset = ((len&0x3F)<<8) | ndr->data[1 + *offset];
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*max_offset = MAX(*max_offset, *offset);
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loops++;
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continue;
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}
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if ((len & 0xC0) != 0) {
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/* its a reserved length field */
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return ndr_pull_error(ndr, NDR_ERR_STRING,
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"BAD DNS NAME component, " \
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"reserved length field: 0x%02x",
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(len &0xC));
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}
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if (*offset + len + 1 > ndr->data_size) {
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return ndr_pull_error(ndr, NDR_ERR_STRING,
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"BAD DNS NAME component, "\
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"length too long");
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}
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*component = (uint8_t*)talloc_strndup(ndr,
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(const char *)&ndr->data[1 + *offset], len);
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NDR_ERR_HAVE_NO_MEMORY(*component);
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*offset += len + 1;
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*max_offset = MAX(*max_offset, *offset);
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return NDR_ERR_SUCCESS;
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}
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/* too many pointers */
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return ndr_pull_error(ndr, NDR_ERR_STRING,
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"BAD DNS NAME component, too many pointers");
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}
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/**
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pull a dns_string from the wire
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*/
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_PUBLIC_ enum ndr_err_code ndr_pull_dns_string(struct ndr_pull *ndr,
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int ndr_flags,
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const char **s)
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{
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uint32_t offset = ndr->offset;
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uint32_t max_offset = offset;
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unsigned num_components;
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char *name;
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if (!(ndr_flags & NDR_SCALARS)) {
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return NDR_ERR_SUCCESS;
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}
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name = talloc_strdup(ndr->current_mem_ctx, "");
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/* break up name into a list of components */
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for (num_components=0; num_components<MAX_COMPONENTS;
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num_components++) {
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uint8_t *component = NULL;
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NDR_CHECK(ndr_pull_component(ndr, &component, &offset,
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&max_offset));
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if (component == NULL) break;
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if (num_components > 0) {
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name = talloc_asprintf_append_buffer(name, ".%s",
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component);
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} else {
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name = talloc_asprintf_append_buffer(name, "%s",
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component);
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}
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NDR_ERR_HAVE_NO_MEMORY(name);
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}
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if (num_components == MAX_COMPONENTS) {
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return ndr_pull_error(ndr, NDR_ERR_STRING,
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"BAD DNS NAME too many components");
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}
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(*s) = name;
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ndr->offset = max_offset;
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return NDR_ERR_SUCCESS;
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}
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/**
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push a dns string to the wire
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*/
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_PUBLIC_ enum ndr_err_code ndr_push_dns_string(struct ndr_push *ndr,
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int ndr_flags,
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const char *s)
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{
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if (!(ndr_flags & NDR_SCALARS)) {
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return NDR_ERR_SUCCESS;
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}
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while (s && *s) {
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enum ndr_err_code ndr_err;
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char *compname;
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size_t complen;
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uint32_t offset;
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if (!(ndr->flags & LIBNDR_FLAG_NO_COMPRESSION)) {
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/* see if we have pushed the remaining string already,
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* if so we use a label pointer to this string
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*/
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ndr_err = ndr_token_retrieve_cmp_fn(&ndr->dns_string_list, s,
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&offset,
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(comparison_fn_t)strcmp,
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false);
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if (NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
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uint8_t b[2];
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if (offset > 0x3FFF) {
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return ndr_push_error(ndr, NDR_ERR_STRING,
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"offset for dns string " \
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"label pointer " \
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"%u[%08X] > 0x00003FFF",
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offset, offset);
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}
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b[0] = 0xC0 | (offset>>8);
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b[1] = (offset & 0xFF);
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return ndr_push_bytes(ndr, b, 2);
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}
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}
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complen = strcspn(s, ".");
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/* we need to make sure the length fits into 6 bytes */
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if (complen > 0x3F) {
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return ndr_push_error(ndr, NDR_ERR_STRING,
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"component length %u[%08X] > " \
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"0x0000003F",
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(unsigned)complen,
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(unsigned)complen);
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}
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compname = talloc_asprintf(ndr, "%c%*.*s",
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(unsigned char)complen,
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(unsigned char)complen,
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(unsigned char)complen, s);
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NDR_ERR_HAVE_NO_MEMORY(compname);
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/* remember the current component + the rest of the string
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* so it can be reused later
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*/
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if (!(ndr->flags & LIBNDR_FLAG_NO_COMPRESSION)) {
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NDR_CHECK(ndr_token_store(ndr, &ndr->dns_string_list, s,
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ndr->offset));
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}
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/* push just this component into the blob */
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NDR_CHECK(ndr_push_bytes(ndr, (const uint8_t *)compname,
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complen+1));
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talloc_free(compname);
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s += complen;
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if (*s == '.') s++;
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}
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/* if we reach the end of the string and have pushed the last component
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* without using a label pointer, we need to terminate the string
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*/
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return ndr_push_bytes(ndr, (const uint8_t *)"", 1);
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}
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_PUBLIC_ enum ndr_err_code ndr_pull_dns_txt_record(struct ndr_pull *ndr, int ndr_flags, struct dns_txt_record *r)
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{
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NDR_PULL_CHECK_FLAGS(ndr, ndr_flags);
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if (ndr_flags & NDR_SCALARS) {
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enum ndr_err_code ndr_err;
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uint32_t data_size = ndr->data_size;
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uint32_t record_size = 0;
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ndr_err = ndr_token_retrieve(&ndr->array_size_list, r,
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&record_size);
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if (NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
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NDR_PULL_NEED_BYTES(ndr, record_size);
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ndr->data_size = ndr->offset + record_size;
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}
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NDR_CHECK(ndr_pull_align(ndr, 1));
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NDR_CHECK(ndr_pull_dnsp_string_list(ndr, NDR_SCALARS, &r->txt));
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NDR_CHECK(ndr_pull_trailer_align(ndr, 1));
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ndr->data_size = data_size;
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}
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if (ndr_flags & NDR_BUFFERS) {
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}
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return NDR_ERR_SUCCESS;
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}
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_PUBLIC_ enum ndr_err_code ndr_push_dns_res_rec(struct ndr_push *ndr,
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int ndr_flags,
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const struct dns_res_rec *r)
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{
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uint32_t _flags_save_STRUCT = ndr->flags;
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uint32_t _saved_offset1, _saved_offset2;
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uint16_t length;
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ndr_set_flags(&ndr->flags, LIBNDR_PRINT_ARRAY_HEX |
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LIBNDR_FLAG_NOALIGN);
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if (ndr_flags & NDR_SCALARS) {
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uint32_t _flags_save_name = ndr->flags;
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NDR_CHECK(ndr_push_align(ndr, 4));
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switch (r->rr_type) {
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case DNS_QTYPE_TKEY:
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case DNS_QTYPE_TSIG:
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ndr_set_flags(&ndr->flags, LIBNDR_FLAG_NO_COMPRESSION);
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break;
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default:
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break;
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}
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NDR_CHECK(ndr_push_dns_string(ndr, NDR_SCALARS, r->name));
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ndr->flags = _flags_save_name;
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NDR_CHECK(ndr_push_dns_qtype(ndr, NDR_SCALARS, r->rr_type));
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NDR_CHECK(ndr_push_dns_qclass(ndr, NDR_SCALARS, r->rr_class));
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NDR_CHECK(ndr_push_uint32(ndr, NDR_SCALARS, r->ttl));
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_saved_offset1 = ndr->offset;
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NDR_CHECK(ndr_push_uint16(ndr, NDR_SCALARS, 0));
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if (r->length > 0) {
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uint32_t _saved_offset3;
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NDR_CHECK(ndr_push_set_switch_value(ndr, &r->rdata,
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r->rr_type));
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_saved_offset3 = ndr->offset;
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NDR_CHECK(ndr_push_dns_rdata(ndr, NDR_SCALARS,
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&r->rdata));
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if ((ndr->offset != _saved_offset3) &&
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(r->unexpected.length > 0)) {
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/*
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* ndr_push_dns_rdata pushed a known
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* record, but we have something
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* unexpected. That's invalid.
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*/
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return ndr_push_error(ndr,
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NDR_ERR_LENGTH,
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"Invalid...Unexpected " \
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"blob length is too " \
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"large");
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}
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}
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if (r->unexpected.length > UINT16_MAX) {
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return ndr_push_error(ndr, NDR_ERR_LENGTH,
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"Unexpected blob length "\
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"is too large");
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}
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NDR_CHECK(ndr_push_bytes(ndr, r->unexpected.data,
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r->unexpected.length));
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NDR_CHECK(ndr_push_trailer_align(ndr, 4));
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length = ndr->offset - (_saved_offset1 + 2);
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_saved_offset2 = ndr->offset;
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ndr->offset = _saved_offset1;
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NDR_CHECK(ndr_push_uint16(ndr, NDR_SCALARS, length));
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ndr->offset = _saved_offset2;
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}
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if (ndr_flags & NDR_BUFFERS) {
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NDR_CHECK(ndr_push_dns_rdata(ndr, NDR_BUFFERS,
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&r->rdata));
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}
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ndr->flags = _flags_save_STRUCT;
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return NDR_ERR_SUCCESS;
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}
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_PUBLIC_ enum ndr_err_code ndr_pull_dns_res_rec(struct ndr_pull *ndr,
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int ndr_flags,
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struct dns_res_rec *r)
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{
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uint32_t _flags_save_STRUCT = ndr->flags;
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uint32_t _saved_offset1;
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uint32_t pad, length;
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ndr_set_flags(&ndr->flags, LIBNDR_PRINT_ARRAY_HEX |
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LIBNDR_FLAG_NOALIGN);
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if (ndr_flags & NDR_SCALARS) {
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NDR_CHECK(ndr_pull_align(ndr, 4));
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NDR_CHECK(ndr_pull_dns_string(ndr, NDR_SCALARS, &r->name));
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NDR_CHECK(ndr_pull_dns_qtype(ndr, NDR_SCALARS, &r->rr_type));
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NDR_CHECK(ndr_pull_dns_qclass(ndr, NDR_SCALARS, &r->rr_class));
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NDR_CHECK(ndr_pull_uint32(ndr, NDR_SCALARS, &r->ttl));
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NDR_CHECK(ndr_pull_uint16(ndr, NDR_SCALARS, &r->length));
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_saved_offset1 = ndr->offset;
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if (r->length > 0) {
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NDR_CHECK(ndr_token_store(ndr, &ndr->array_size_list,
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&r->rdata,
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r->length));
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NDR_CHECK(ndr_pull_set_switch_value(ndr, &r->rdata,
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r->rr_type));
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NDR_CHECK(ndr_pull_dns_rdata(ndr, NDR_SCALARS,
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&r->rdata));
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} else {
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ZERO_STRUCT(r->rdata);
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}
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length = ndr->offset - _saved_offset1;
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if (length > r->length) {
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return ndr_pull_error(ndr, NDR_ERR_LENGTH, "TODO");
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}
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r->unexpected = data_blob_null;
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pad = r->length - length;
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if (pad > 0) {
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NDR_PULL_NEED_BYTES(ndr, pad);
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r->unexpected = data_blob_talloc(ndr->current_mem_ctx,
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ndr->data +
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ndr->offset,
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pad);
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if (r->unexpected.data == NULL) {
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return ndr_pull_error(ndr,
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NDR_ERR_ALLOC,
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"Failed to allocate a " \
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"data blob");
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}
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ndr->offset += pad;
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}
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NDR_CHECK(ndr_pull_trailer_align(ndr, 4));
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}
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if (ndr_flags & NDR_BUFFERS) {
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NDR_CHECK(ndr_pull_dns_rdata(ndr, NDR_BUFFERS, &r->rdata));
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}
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ndr->flags = _flags_save_STRUCT;
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return NDR_ERR_SUCCESS;
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}
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