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/*
Unix SMB/CIFS implementation.
DNS server handler for queries
Copyright (C) 2010 Kai Blin <kai@samba.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "smbd/service_task.h"
#include "libcli/util/werror.h"
#include "librpc/ndr/libndr.h"
#include "librpc/gen_ndr/ndr_dns.h"
#include "librpc/gen_ndr/ndr_dnsp.h"
#include <ldb.h>
#include "param/param.h"
#include "dsdb/samdb/samdb.h"
#include "dsdb/common/util.h"
#include "dns_server/dns_server.h"
#include "libcli/dns/libdns.h"
#include "lib/util/util_net.h"
static WERROR create_response_rr(const struct dns_name_question *question,
const struct dnsp_DnssrvRpcRecord *rec,
struct dns_res_rec **answers, uint16_t *ancount)
{
struct dns_res_rec *ans = *answers;
uint16_t ai = *ancount;
char *tmp;
uint32_t i;
ZERO_STRUCT(ans[ai]);
switch (rec->wType) {
case DNS_QTYPE_CNAME:
ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname);
if (ans[ai].rdata.cname_record == NULL) {
return WERR_NOMEM;
}
break;
case DNS_QTYPE_A:
ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
if (ans[ai].rdata.ipv4_record == NULL) {
return WERR_NOMEM;
}
break;
case DNS_QTYPE_AAAA:
ans[ai].rdata.ipv6_record = rec->data.ipv6;
break;
case DNS_TYPE_NS:
ans[ai].rdata.ns_record = rec->data.ns;
break;
case DNS_QTYPE_SRV:
ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
ans[ai].rdata.srv_record.weight = rec->data.srv.wWeight;
ans[ai].rdata.srv_record.port = rec->data.srv.wPort;
ans[ai].rdata.srv_record.target = rec->data.srv.nameTarget;
break;
case DNS_QTYPE_SOA:
ans[ai].rdata.soa_record.mname = rec->data.soa.mname;
ans[ai].rdata.soa_record.rname = rec->data.soa.rname;
ans[ai].rdata.soa_record.serial = rec->data.soa.serial;
ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
ans[ai].rdata.soa_record.retry = rec->data.soa.retry;
ans[ai].rdata.soa_record.expire = rec->data.soa.expire;
ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
break;
case DNS_QTYPE_PTR:
ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
break;
case DNS_QTYPE_TXT:
tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
if (tmp == NULL) {
return WERR_NOMEM;
}
for (i=1; i<rec->data.txt.count; i++) {
tmp = talloc_asprintf_append(tmp, " \"%s\"",
rec->data.txt.str[i]);
if (tmp == NULL) {
return WERR_NOMEM;
}
}
ans[ai].rdata.txt_record.txt = tmp;
break;
default:
DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
return DNS_ERR(NOT_IMPLEMENTED);
}
ans[ai].name = talloc_strdup(ans, question->name);
if (ans[ai].name == NULL) {
return WERR_NOMEM;
}
ans[ai].rr_type = rec->wType;
ans[ai].rr_class = DNS_QCLASS_IN;
ans[ai].ttl = rec->dwTtlSeconds;
ans[ai].length = UINT16_MAX;
ai++;
*answers = ans;
*ancount = ai;
return WERR_OK;
}
static WERROR ask_forwarder(struct dns_server *dns,
TALLOC_CTX *mem_ctx,
struct dns_name_question *question,
struct dns_res_rec **answers, uint16_t *ancount,
struct dns_res_rec **nsrecs, uint16_t *nscount,
struct dns_res_rec **additional, uint16_t *arcount)
{
struct tevent_context *ev = tevent_context_init(mem_ctx);
struct dns_name_packet *out_packet, *in_packet;
uint16_t id = random();
DATA_BLOB out, in;
enum ndr_err_code ndr_err;
WERROR werr = WERR_OK;
struct tevent_req *req;
const char *forwarder = lpcfg_dns_forwarder(dns->task->lp_ctx);
if (!is_ipaddress(forwarder)) {
DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
"an IP address\n", forwarder));
return DNS_ERR(NAME_ERROR);
}
out_packet = talloc_zero(mem_ctx, struct dns_name_packet);
W_ERROR_HAVE_NO_MEMORY(out_packet);
out_packet->id = id;
out_packet->operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
out_packet->qdcount = 1;
out_packet->questions = question;
ndr_err = ndr_push_struct_blob(&out, mem_ctx, out_packet,
(ndr_push_flags_fn_t)ndr_push_dns_name_packet);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
return DNS_ERR(SERVER_FAILURE);
}
req = dns_udp_request_send(mem_ctx, ev, forwarder, out.data, out.length);
W_ERROR_HAVE_NO_MEMORY(req);
if(!tevent_req_poll(req, ev)) {
return DNS_ERR(SERVER_FAILURE);
}
werr = dns_udp_request_recv(req, mem_ctx, &in.data, &in.length);
W_ERROR_NOT_OK_RETURN(werr);
in_packet = talloc_zero(mem_ctx, struct dns_name_packet);
W_ERROR_HAVE_NO_MEMORY(in_packet);
ndr_err = ndr_pull_struct_blob(&in, in_packet, in_packet,
(ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
return DNS_ERR(SERVER_FAILURE);
}
if (in_packet->id != id) {
DEBUG(0, ("DNS packet id mismatch: 0x%0x, expected 0x%0x\n",
in_packet->id, id));
return DNS_ERR(NAME_ERROR);
}
*ancount = in_packet->ancount;
*answers = talloc_move(mem_ctx, &in_packet->answers);
*nscount = in_packet->nscount;
*nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
*arcount = in_packet->arcount;
*additional = talloc_move(mem_ctx, &in_packet->additional);
return werr;
}
static WERROR handle_question(struct dns_server *dns,
TALLOC_CTX *mem_ctx,
const struct dns_name_question *question,
struct dns_res_rec **answers, uint16_t *ancount)
{
struct dns_res_rec *ans;
WERROR werror;
unsigned int ri;
struct dnsp_DnssrvRpcRecord *recs;
uint16_t rec_count, ai = 0;
struct ldb_dn *dn = NULL;
werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
W_ERROR_NOT_OK_RETURN(werror);
werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
W_ERROR_NOT_OK_RETURN(werror);
ans = talloc_zero_array(mem_ctx, struct dns_res_rec, rec_count);
W_ERROR_HAVE_NO_MEMORY(ans);
for (ri = 0; ri < rec_count; ri++) {
if ((question->question_type != DNS_QTYPE_ALL) &&
(recs[ri].wType != question->question_type)) {
continue;
}
werror = create_response_rr(question, &recs[ri], &ans, &ai);
W_ERROR_NOT_OK_RETURN(werror);
}
if (ai == 0) {
return DNS_ERR(NAME_ERROR);
}
*ancount = ai;
*answers = ans;
return WERR_OK;
}
WERROR dns_server_process_query(struct dns_server *dns,
struct dns_request_state *state,
TALLOC_CTX *mem_ctx,
struct dns_name_packet *in,
struct dns_res_rec **answers, uint16_t *ancount,
struct dns_res_rec **nsrecs, uint16_t *nscount,
struct dns_res_rec **additional, uint16_t *arcount)
{
uint16_t num_answers=0, num_nsrecs=0, num_additional=0;
struct dns_res_rec *ans=NULL, *ns=NULL, *adds=NULL;
WERROR werror;
if (in->qdcount != 1) {
return DNS_ERR(FORMAT_ERROR);
}
/* Windows returns NOT_IMPLEMENTED on this as well */
if (in->questions[0].question_class == DNS_QCLASS_NONE) {
return DNS_ERR(NOT_IMPLEMENTED);
}
if (dns_authorative_for_zone(dns, in->questions[0].name)) {
state->flags |= DNS_FLAG_AUTHORITATIVE;
werror = handle_question(dns, mem_ctx, &in->questions[0],
&ans, &num_answers);
} else {
if (state->flags & DNS_FLAG_RECURSION_DESIRED &&
state->flags & DNS_FLAG_RECURSION_AVAIL) {
DEBUG(2, ("Not authorative for '%s', forwarding\n",
in->questions[0].name));
werror = ask_forwarder(dns, mem_ctx, &in->questions[0],
&ans, &num_answers,
&ns, &num_nsrecs,
&adds, &num_additional);
} else {
werror = DNS_ERR(NAME_ERROR);
}
}
W_ERROR_NOT_OK_GOTO(werror, query_failed);
*answers = ans;
*ancount = num_answers;
/*FIXME: Do something for these */
*nsrecs = ns;
*nscount = num_nsrecs;
*additional = adds;
*arcount = num_additional;
return WERR_OK;
query_failed:
/*FIXME: add our SOA record to nsrecs */
return werror;
}
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