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https://github.com/samba-team/samba.git
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393 lines
11 KiB
C
393 lines
11 KiB
C
/*
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Unix SMB/CIFS implementation.
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DNS server handler for queries
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Copyright (C) 2010 Kai Blin <kai@samba.org>
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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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#include "includes.h"
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#include "smbd/service_task.h"
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#include "libcli/util/werror.h"
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#include "librpc/ndr/libndr.h"
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#include "librpc/gen_ndr/ndr_dns.h"
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#include "librpc/gen_ndr/ndr_dnsp.h"
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#include <ldb.h>
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#include "param/param.h"
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#include "dsdb/samdb/samdb.h"
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#include "dsdb/common/util.h"
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#include "dns_server/dns_server.h"
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#include "libcli/dns/libdns.h"
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#include "lib/util/util_net.h"
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#include "lib/util/tevent_werror.h"
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static WERROR create_response_rr(const struct dns_name_question *question,
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const struct dnsp_DnssrvRpcRecord *rec,
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struct dns_res_rec **answers, uint16_t *ancount)
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{
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struct dns_res_rec *ans = *answers;
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uint16_t ai = *ancount;
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char *tmp;
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uint32_t i;
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ZERO_STRUCT(ans[ai]);
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switch (rec->wType) {
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case DNS_QTYPE_CNAME:
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ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname);
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if (ans[ai].rdata.cname_record == NULL) {
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return WERR_NOMEM;
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}
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break;
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case DNS_QTYPE_A:
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ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
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if (ans[ai].rdata.ipv4_record == NULL) {
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return WERR_NOMEM;
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}
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break;
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case DNS_QTYPE_AAAA:
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ans[ai].rdata.ipv6_record = talloc_strdup(ans, rec->data.ipv6);
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W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv6_record);
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break;
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case DNS_TYPE_NS:
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ans[ai].rdata.ns_record = rec->data.ns;
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break;
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case DNS_QTYPE_SRV:
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ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
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ans[ai].rdata.srv_record.weight = rec->data.srv.wWeight;
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ans[ai].rdata.srv_record.port = rec->data.srv.wPort;
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ans[ai].rdata.srv_record.target = talloc_strdup(
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ans, rec->data.srv.nameTarget);
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if (ans[ai].rdata.srv_record.target == NULL) {
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return WERR_NOMEM;
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}
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break;
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case DNS_QTYPE_SOA:
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ans[ai].rdata.soa_record.mname = talloc_strdup(
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ans, rec->data.soa.mname);
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if (ans[ai].rdata.soa_record.mname == NULL) {
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return WERR_NOMEM;
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}
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ans[ai].rdata.soa_record.rname = talloc_strdup(
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ans, rec->data.soa.rname);
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if (ans[ai].rdata.soa_record.rname == NULL) {
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return WERR_NOMEM;
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}
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ans[ai].rdata.soa_record.serial = rec->data.soa.serial;
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ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
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ans[ai].rdata.soa_record.retry = rec->data.soa.retry;
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ans[ai].rdata.soa_record.expire = rec->data.soa.expire;
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ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
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break;
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case DNS_QTYPE_PTR:
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ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
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break;
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case DNS_QTYPE_TXT:
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tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
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if (tmp == NULL) {
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return WERR_NOMEM;
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}
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for (i=1; i<rec->data.txt.count; i++) {
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tmp = talloc_asprintf_append_buffer(
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tmp, " \"%s\"", rec->data.txt.str[i]);
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if (tmp == NULL) {
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return WERR_NOMEM;
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}
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}
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ans[ai].rdata.txt_record.txt = tmp;
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break;
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default:
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DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
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return DNS_ERR(NOT_IMPLEMENTED);
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}
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ans[ai].name = talloc_strdup(ans, question->name);
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if (ans[ai].name == NULL) {
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return WERR_NOMEM;
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}
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ans[ai].rr_type = rec->wType;
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ans[ai].rr_class = DNS_QCLASS_IN;
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ans[ai].ttl = rec->dwTtlSeconds;
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ans[ai].length = UINT16_MAX;
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ai++;
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*answers = ans;
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*ancount = ai;
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return WERR_OK;
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}
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struct ask_forwarder_state {
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struct tevent_context *ev;
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uint16_t id;
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struct dns_name_packet in_packet;
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};
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static void ask_forwarder_done(struct tevent_req *subreq);
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static struct tevent_req *ask_forwarder_send(
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TALLOC_CTX *mem_ctx, struct tevent_context *ev,
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const char *forwarder, struct dns_name_question *question)
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{
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struct tevent_req *req, *subreq;
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struct ask_forwarder_state *state;
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struct dns_name_packet out_packet = { 0, };
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DATA_BLOB out_blob;
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enum ndr_err_code ndr_err;
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req = tevent_req_create(mem_ctx, &state, struct ask_forwarder_state);
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if (req == NULL) {
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return NULL;
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}
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state->ev = ev;
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generate_random_buffer((uint8_t *)&state->id, sizeof(state->id));
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if (!is_ipaddress(forwarder)) {
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DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
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"an IP address\n", forwarder));
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tevent_req_werror(req, DNS_ERR(NAME_ERROR));
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return tevent_req_post(req, ev);
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}
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out_packet.id = state->id;
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out_packet.operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
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out_packet.qdcount = 1;
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out_packet.questions = question;
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ndr_err = ndr_push_struct_blob(
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&out_blob, state, &out_packet,
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(ndr_push_flags_fn_t)ndr_push_dns_name_packet);
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if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
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tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
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return tevent_req_post(req, ev);
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}
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subreq = dns_udp_request_send(state, ev, forwarder, out_blob.data,
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out_blob.length);
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if (tevent_req_nomem(subreq, req)) {
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return tevent_req_post(req, ev);
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}
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tevent_req_set_callback(subreq, ask_forwarder_done, req);
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return req;
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}
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static void ask_forwarder_done(struct tevent_req *subreq)
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{
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struct tevent_req *req = tevent_req_callback_data(
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subreq, struct tevent_req);
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struct ask_forwarder_state *state = tevent_req_data(
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req, struct ask_forwarder_state);
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DATA_BLOB in_blob;
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enum ndr_err_code ndr_err;
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WERROR ret;
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ret = dns_udp_request_recv(subreq, state,
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&in_blob.data, &in_blob.length);
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TALLOC_FREE(subreq);
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if (tevent_req_werror(req, ret)) {
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return;
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}
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ndr_err = ndr_pull_struct_blob(
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&in_blob, state, &state->in_packet,
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(ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
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if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
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tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
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return;
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}
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if (state->in_packet.id != state->id) {
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tevent_req_werror(req, DNS_ERR(NAME_ERROR));
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return;
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}
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tevent_req_done(req);
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}
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static WERROR ask_forwarder_recv(
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struct tevent_req *req, TALLOC_CTX *mem_ctx,
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struct dns_res_rec **answers, uint16_t *ancount,
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struct dns_res_rec **nsrecs, uint16_t *nscount,
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struct dns_res_rec **additional, uint16_t *arcount)
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{
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struct ask_forwarder_state *state = tevent_req_data(
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req, struct ask_forwarder_state);
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struct dns_name_packet *in_packet = &state->in_packet;
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WERROR err;
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if (tevent_req_is_werror(req, &err)) {
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return err;
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}
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*ancount = in_packet->ancount;
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*answers = talloc_move(mem_ctx, &in_packet->answers);
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*nscount = in_packet->nscount;
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*nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
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*arcount = in_packet->arcount;
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*additional = talloc_move(mem_ctx, &in_packet->additional);
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return WERR_OK;
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}
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static WERROR handle_question(struct dns_server *dns,
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TALLOC_CTX *mem_ctx,
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const struct dns_name_question *question,
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struct dns_res_rec **answers, uint16_t *ancount)
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{
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struct dns_res_rec *ans;
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WERROR werror;
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unsigned int ri;
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struct dnsp_DnssrvRpcRecord *recs;
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uint16_t rec_count, ai = 0;
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struct ldb_dn *dn = NULL;
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werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
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W_ERROR_NOT_OK_RETURN(werror);
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werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
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W_ERROR_NOT_OK_RETURN(werror);
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ans = talloc_zero_array(mem_ctx, struct dns_res_rec, rec_count);
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W_ERROR_HAVE_NO_MEMORY(ans);
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for (ri = 0; ri < rec_count; ri++) {
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if ((question->question_type != DNS_QTYPE_ALL) &&
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(recs[ri].wType != question->question_type)) {
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continue;
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}
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werror = create_response_rr(question, &recs[ri], &ans, &ai);
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W_ERROR_NOT_OK_RETURN(werror);
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}
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if (ai == 0) {
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return DNS_ERR(NAME_ERROR);
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}
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*ancount = ai;
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*answers = ans;
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return WERR_OK;
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}
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struct dns_server_process_query_state {
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struct dns_res_rec *answers;
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uint16_t ancount;
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struct dns_res_rec *nsrecs;
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uint16_t nscount;
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struct dns_res_rec *additional;
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uint16_t arcount;
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};
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static void dns_server_process_query_got_response(struct tevent_req *subreq);
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struct tevent_req *dns_server_process_query_send(
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TALLOC_CTX *mem_ctx, struct tevent_context *ev,
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struct dns_server *dns, struct dns_request_state *req_state,
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const struct dns_name_packet *in)
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{
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struct tevent_req *req, *subreq;
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struct dns_server_process_query_state *state;
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req = tevent_req_create(mem_ctx, &state,
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struct dns_server_process_query_state);
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if (req == NULL) {
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return NULL;
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}
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if (in->qdcount != 1) {
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tevent_req_werror(req, DNS_ERR(FORMAT_ERROR));
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return tevent_req_post(req, ev);
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}
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/* Windows returns NOT_IMPLEMENTED on this as well */
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if (in->questions[0].question_class == DNS_QCLASS_NONE) {
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tevent_req_werror(req, DNS_ERR(NOT_IMPLEMENTED));
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return tevent_req_post(req, ev);
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}
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if (dns_authorative_for_zone(dns, in->questions[0].name)) {
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WERROR err;
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req_state->flags |= DNS_FLAG_AUTHORITATIVE;
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err = handle_question(dns, state, &in->questions[0],
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&state->answers, &state->ancount);
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if (tevent_req_werror(req, err)) {
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return tevent_req_post(req, ev);
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}
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tevent_req_done(req);
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return tevent_req_post(req, ev);
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}
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if ((req_state->flags & DNS_FLAG_RECURSION_DESIRED) &&
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(req_state->flags & DNS_FLAG_RECURSION_AVAIL)) {
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DEBUG(2, ("Not authoritative for '%s', forwarding\n",
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in->questions[0].name));
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subreq = ask_forwarder_send(
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state, ev, lpcfg_dns_forwarder(dns->task->lp_ctx),
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&in->questions[0]);
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if (tevent_req_nomem(subreq, req)) {
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return tevent_req_post(req, ev);
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}
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tevent_req_set_callback(
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subreq, dns_server_process_query_got_response, req);
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return req;
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}
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tevent_req_werror(req, DNS_ERR(NAME_ERROR));
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return tevent_req_post(req, ev);
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}
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static void dns_server_process_query_got_response(struct tevent_req *subreq)
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{
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struct tevent_req *req = tevent_req_callback_data(
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subreq, struct tevent_req);
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struct dns_server_process_query_state *state = tevent_req_data(
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req, struct dns_server_process_query_state);
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WERROR err;
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err = ask_forwarder_recv(subreq, state,
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&state->answers, &state->ancount,
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&state->nsrecs, &state->nscount,
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&state->additional, &state->arcount);
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TALLOC_FREE(subreq);
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if (tevent_req_werror(req, err)) {
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return;
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}
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tevent_req_done(req);
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}
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WERROR dns_server_process_query_recv(
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struct tevent_req *req, TALLOC_CTX *mem_ctx,
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struct dns_res_rec **answers, uint16_t *ancount,
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struct dns_res_rec **nsrecs, uint16_t *nscount,
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struct dns_res_rec **additional, uint16_t *arcount)
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{
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struct dns_server_process_query_state *state = tevent_req_data(
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req, struct dns_server_process_query_state);
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WERROR err;
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if (tevent_req_is_werror(req, &err)) {
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return err;
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}
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*answers = talloc_move(mem_ctx, &state->answers);
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*ancount = state->ancount;
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*nsrecs = talloc_move(mem_ctx, &state->nsrecs);
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*nscount = state->nscount;
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*additional = talloc_move(mem_ctx, &state->additional);
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*arcount = state->arcount;
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return WERR_OK;
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}
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