Kea: dns_client.cc Source File

| Kea 2.2.0

dns_client.cc
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1// Copyright (C) 2013-2021 Internet Systems Consortium, Inc. ("ISC")
2//
3// This Source Code Form is subject to the terms of the Mozilla Public
4// License, v. 2.0. If a copy of the MPL was not distributed with this
5// file, You can obtain one at http://mozilla.org/MPL/2.0/.
6
7#include <config.h>
8
9#include <d2srv/d2_log.h>
10#include <d2srv/dns_client.h>
11#include <dns/messagerenderer.h>
12#include <stats/stats_mgr.h>
13#include <limits>
14
15namespace isc {
16namespace d2 {
17
18namespace {
19
20// OutputBuffer objects are pre-allocated before data is written to them.
21// This is a default number of bytes for the buffers we create within
22// DNSClient class.
23const size_t DEFAULT_BUFFER_SIZE = 128;
24
25}
26
27using namespace isc::util;
28using namespace isc::asiolink;
29using namespace isc::asiodns;
30using namespace isc::dns;
31using namespace isc::stats;
32
33// This class provides the implementation for the DNSClient. This allows for
34// the separation of the DNSClient interface from the implementation details.
35// Currently, implementation uses IOFetch object to handle asynchronous
36// communication with the DNS. This design may be revisited in the future. If
37// implementation is changed, the DNSClient API will remain unchanged thanks
38// to this separation.
39 class DNSClientImpl : public asiodns::IOFetch::Callback {
40public:
42 util::OutputBufferPtr in_buf_;
43
54 D2UpdateMessagePtr& response_;
55
58 DNSClient::Callback* callback_;
59
61 DNSClient::Protocol proto_;
62
64 dns::TSIGContextPtr tsig_context_;
65
67 std::string tsig_key_name_;
68
78 DNSClientImpl(D2UpdateMessagePtr& response_placeholder,
79 DNSClient::Callback* callback,
80 const DNSClient::Protocol proto);
81
83 virtual ~DNSClientImpl();
84
89 virtual void operator()(asiodns::IOFetch::Result result);
90
103 void doUpdate(asiolink::IOService& io_service,
104 const asiolink::IOAddress& ns_addr,
105 const uint16_t ns_port,
106 D2UpdateMessage& update,
107 const unsigned int wait,
108 const D2TsigKeyPtr& tsig_key);
109
114 DNSClient::Status getStatus(const asiodns::IOFetch::Result result);
115
121 void incrStats(const std::string& stat, bool update_key = true);
122};
123
124DNSClientImpl::DNSClientImpl(D2UpdateMessagePtr& response_placeholder,
125 DNSClient::Callback* callback,
126 const DNSClient::Protocol proto)
127 : in_buf_(new OutputBuffer(DEFAULT_BUFFER_SIZE)),
128 response_(response_placeholder), callback_(callback), proto_(proto) {
129
130 // Response should be an empty pointer. It gets populated by the
131 // operator() method.
132 if (response_) {
133 isc_throw(isc::BadValue, "Response buffer pointer should be null");
134 }
135
136 // @todo Currently we only support UDP. The support for TCP is planned for
137 // the future release.
138 if (proto_ == DNSClient::TCP) {
139 isc_throw(isc::NotImplemented, "TCP is currently not supported as a"
140 << " Transport protocol for DNS Updates; please use UDP");
141 }
142
143 // Given that we already eliminated the possibility that TCP is used, it
144 // would be sufficient to check that (proto != DNSClient::UDP). But, once
145 // support TCP is added the check above will disappear and the extra check
146 // will be needed here anyway.
147 // Note that cascaded check is used here instead of:
148 // if (proto_ != DNSClient::TCP && proto_ != DNSClient::UDP)..
149 // because some versions of GCC compiler complain that check above would
150 // be always 'false' due to limited range of enumeration. In fact, it is
151 // possible to pass out of range integral value through enum and it should
152 // be caught here.
153 if (proto_ != DNSClient::TCP) {
154 if (proto_ != DNSClient::UDP) {
155 isc_throw(isc::NotImplemented, "invalid transport protocol type '"
156 << proto_ << "' specified for DNS Updates");
157 }
158 }
159}
160
161DNSClientImpl::~DNSClientImpl() {
162}
163
164void
165DNSClientImpl::operator()(asiodns::IOFetch::Result result) {
166 // Get the status from IO. If no success, we just call user's callback
167 // and pass the status code.
168 DNSClient::Status status = getStatus(result);
169 if (status == DNSClient::SUCCESS) {
170 // Allocate a new response message. (Note that Message::fromWire
171 // may only be run once per message, so we need to start fresh
172 // each time.)
173 response_.reset(new D2UpdateMessage(D2UpdateMessage::INBOUND));
174
175 // Server's response may be corrupted. In such case, fromWire will
176 // throw an exception. We want to catch this exception to return
177 // appropriate status code to the caller and log this event.
178 try {
179 response_->fromWire(in_buf_->getData(), in_buf_->getLength(),
180 tsig_context_.get());
181 incrStats("update-success");
182 } catch (const isc::Exception& ex) {
183 status = DNSClient::INVALID_RESPONSE;
184 LOG_DEBUG(d2_to_dns_logger, isc::log::DBGLVL_TRACE_DETAIL,
185 DHCP_DDNS_INVALID_RESPONSE).arg(ex.what());
186 incrStats("update-error");
187 }
188
189 if (tsig_context_) {
190 // Context is a one-shot deal, get rid of it.
191 tsig_context_.reset();
192 }
193 } else if (status == DNSClient::TIMEOUT) {
194 incrStats("update-timeout");
195 } else {
196 incrStats("update-error");
197 }
198
199 // Once we are done with internal business, let's call a callback supplied
200 // by a caller.
201 if (callback_ != NULL) {
202 (*callback_)(status);
203 }
204}
205
206 DNSClient::Status
207DNSClientImpl::getStatus(const asiodns::IOFetch::Result result) {
208 switch (result) {
209 case IOFetch::SUCCESS:
210 return (DNSClient::SUCCESS);
211
212 case IOFetch::TIME_OUT:
213 return (DNSClient::TIMEOUT);
214
215 case IOFetch::STOPPED:
216 return (DNSClient::IO_STOPPED);
217
218 default:
219 ;
220 }
221 return (DNSClient::OTHER);
222}
223
224void
225DNSClientImpl::doUpdate(asiolink::IOService& io_service,
226 const IOAddress& ns_addr,
227 const uint16_t ns_port,
228 D2UpdateMessage& update,
229 const unsigned int wait,
230 const D2TsigKeyPtr& tsig_key) {
231 // The underlying implementation which we use to send DNS Updates uses
232 // signed integers for timeout. If we want to avoid overflows we need to
233 // respect this limitation here.
234 if (wait > DNSClient::getMaxTimeout()) {
235 isc_throw(isc::BadValue, "A timeout value for DNS Update request must"
236 " not exceed " << DNSClient::getMaxTimeout()
237 << ". Provided timeout value is '" << wait << "'");
238 }
239
240 // Create a TSIG context if we have a key, otherwise clear the context
241 // pointer. Message marshalling uses non-null context is the indicator
242 // that TSIG should be used.
243 if (tsig_key) {
244 tsig_context_ = tsig_key->createContext();
245 tsig_key_name_ = tsig_key->getKeyName().toText();
246 } else {
247 tsig_context_.reset();
248 tsig_key_name_.clear();
249 }
250
251 // A renderer is used by the toWire function which creates the on-wire data
252 // from the DNS Update message. A renderer has its internal buffer where it
253 // renders data by default. However, this buffer can't be directly accessed.
254 // Fortunately, the renderer's API accepts user-supplied buffers. So, let's
255 // create our own buffer and pass it to the renderer so as the message is
256 // rendered to this buffer. Finally, we pass this buffer to IOFetch.
257 dns::MessageRenderer renderer;
258 OutputBufferPtr msg_buf(new OutputBuffer(DEFAULT_BUFFER_SIZE));
259 renderer.setBuffer(msg_buf.get());
260
261 // Render DNS Update message. This may throw a bunch of exceptions if
262 // invalid message object is given.
263 update.toWire(renderer, tsig_context_.get());
264
265 // IOFetch has all the mechanisms that we need to perform asynchronous
266 // communication with the DNS server. The last but one argument points to
267 // this object as a completion callback for the message exchange. As a
268 // result operator()(Status) will be called.
269
270 // Timeout value is explicitly cast to the int type to avoid warnings about
271 // overflows when doing implicit cast. It should have been checked by the
272 // caller that the unsigned timeout value will fit into int.
273 IOFetch io_fetch(IOFetch::UDP, io_service, msg_buf, ns_addr, ns_port,
274 in_buf_, this, static_cast<int>(wait));
275
276 // Post the task to the task queue in the IO service. Caller will actually
277 // run these tasks by executing IOService::run.
278 io_service.post(io_fetch);
279
280 // Update sent statistics.
281 incrStats("update-sent");
282 if (tsig_key) {
283 incrStats("update-signed", false);
284 } else {
285 incrStats("update-unsigned", false);
286 }
287}
288
289void
290DNSClientImpl::incrStats(const std::string& stat, bool update_key) {
291 StatsMgr& mgr = StatsMgr::instance();
292 mgr.addValue(stat, static_cast<int64_t>(1));
293 if (update_key && !tsig_key_name_.empty()) {
294 mgr.addValue(StatsMgr::generateName("key", tsig_key_name_, stat),
295 static_cast<int64_t>(1));
296 }
297}
298
299DNSClient::DNSClient(D2UpdateMessagePtr& response_placeholder,
300 Callback* callback, const DNSClient::Protocol proto)
301 : impl_(new DNSClientImpl(response_placeholder, callback, proto)) {
302}
303
304DNSClient::~DNSClient() {
305}
306
307unsigned int
308DNSClient::getMaxTimeout() {
309 static const unsigned int max_timeout = std::numeric_limits<int>::max();
310 return (max_timeout);
311}
312
313void
314DNSClient::doUpdate(asiolink::IOService& io_service,
315 const IOAddress& ns_addr,
316 const uint16_t ns_port,
317 D2UpdateMessage& update,
318 const unsigned int wait,
319 const D2TsigKeyPtr& tsig_key) {
320 impl_->doUpdate(io_service, ns_addr, ns_port, update, wait, tsig_key);
321}
322
323} // namespace d2
324} // namespace isc
isc::BadValue
A generic exception that is thrown if a parameter given to a method is considered invalid in that con...
Definition: exceptions/exceptions.h:132
isc::Exception
This is a base class for exceptions thrown from the DNS library module.
Definition: exceptions/exceptions.h:23
isc::Exception::what
virtual const char * what() const
Returns a C-style character string of the cause of the exception.
Definition: exceptions/exceptions.cc:32
isc::NotImplemented
A generic exception that is thrown when a function is not implemented.
Definition: exceptions/exceptions.h:166
isc::asiodns::IOFetch::Callback
I/O Fetch Callback.
Definition: io_fetch.h:98
isc::asiodns::IOFetch
Upstream Fetch Processing.
Definition: io_fetch.h:45
isc::asiodns::IOFetch::Result
Result
Result of Upstream Fetch.
Definition: io_fetch.h:70
isc::asiodns::IOFetch::STOPPED
@ STOPPED
Control code, fetch has been stopped.
Definition: io_fetch.h:73
isc::asiodns::IOFetch::TIME_OUT
@ TIME_OUT
Failure, fetch timed out.
Definition: io_fetch.h:72
isc::asiodns::IOFetch::SUCCESS
@ SUCCESS
Success, fetch completed.
Definition: io_fetch.h:71
isc::asiodns::IOFetch::UDP
@ UDP
Definition: io_fetch.h:49
isc::asiolink::IOAddress
The IOAddress class represents an IP addresses (version agnostic)
Definition: io_address.h:45
isc::asiolink::IOService
The IOService class is a wrapper for the ASIO io_service class.
Definition: io_service.h:33
isc::asiolink::IOService::post
void post(const std::function< void()> &callback)
Post a callback to the end of the queue.
Definition: io_service.cc:177
isc::d2::D2UpdateMessage
The D2UpdateMessage encapsulates a DNS Update message.
Definition: d2_update_message.h:89
isc::d2::D2UpdateMessage::toWire
void toWire(dns::AbstractMessageRenderer &renderer, dns::TSIGContext *const tsig_ctx=NULL)
Encode outgoing message into wire format.
Definition: d2_update_message.cc:105
isc::d2::D2UpdateMessage::INBOUND
@ INBOUND
Definition: d2_update_message.h:95
isc::d2::DNSClientImpl
Definition: dns_client.cc:39
isc::d2::DNSClientImpl::incrStats
void incrStats(const std::string &stat, bool update_key=true)
This function updates statistics.
Definition: dns_client.cc:290
isc::d2::DNSClientImpl::operator()
virtual void operator()(asiodns::IOFetch::Result result)
This internal callback is called when the DNS update message exchange is complete.
Definition: dns_client.cc:165
isc::d2::DNSClientImpl::tsig_key_name_
std::string tsig_key_name_
TSIG key name for stats.
Definition: dns_client.cc:67
isc::d2::DNSClientImpl::callback_
DNSClient::Callback * callback_
A caller-supplied external callback which is invoked when DNS message exchange is complete or interru...
Definition: dns_client.cc:58
isc::d2::DNSClientImpl::tsig_context_
dns::TSIGContextPtr tsig_context_
TSIG context used to sign outbound and verify inbound messages.
Definition: dns_client.cc:64
isc::d2::DNSClientImpl::response_
D2UpdateMessagePtr & response_
A caller-supplied object which will hold the parsed response from DNS.
Definition: dns_client.cc:54
isc::d2::DNSClientImpl::~DNSClientImpl
virtual ~DNSClientImpl()
Destructor.
Definition: dns_client.cc:161
isc::d2::DNSClientImpl::DNSClientImpl
DNSClientImpl(D2UpdateMessagePtr &response_placeholder, DNSClient::Callback *callback, const DNSClient::Protocol proto)
Constructor.
Definition: dns_client.cc:124
isc::d2::DNSClientImpl::doUpdate
void doUpdate(asiolink::IOService &io_service, const asiolink::IOAddress &ns_addr, const uint16_t ns_port, D2UpdateMessage &update, const unsigned int wait, const D2TsigKeyPtr &tsig_key)
Starts asynchronous DNS Update using TSIG.
Definition: dns_client.cc:225
isc::d2::DNSClientImpl::proto_
DNSClient::Protocol proto_
A Transport Layer protocol used to communicate with a DNS.
Definition: dns_client.cc:61
isc::d2::DNSClientImpl::getStatus
DNSClient::Status getStatus(const asiodns::IOFetch::Result result)
This function maps the IO error to the DNSClient error.
Definition: dns_client.cc:207
isc::d2::DNSClientImpl::in_buf_
util::OutputBufferPtr in_buf_
A buffer holding response from a DNS.
Definition: dns_client.cc:42
isc::d2::DNSClient::Callback
Callback for the DNSClient class.
Definition: dns_client.h:72
isc::d2::DNSClient::~DNSClient
~DNSClient()
Virtual destructor, does nothing.
Definition: dns_client.cc:304
isc::d2::DNSClient::DNSClient
DNSClient(D2UpdateMessagePtr &response_placeholder, Callback *callback, const Protocol proto=UDP)
Constructor.
Definition: dns_client.cc:299
isc::d2::DNSClient::doUpdate
void doUpdate(asiolink::IOService &io_service, const asiolink::IOAddress &ns_addr, const uint16_t ns_port, D2UpdateMessage &update, const unsigned int wait, const D2TsigKeyPtr &tsig_key=D2TsigKeyPtr())
Start asynchronous DNS Update with TSIG.
Definition: dns_client.cc:314
isc::d2::DNSClient::getMaxTimeout
static unsigned int getMaxTimeout()
Returns maximal allowed timeout value accepted by DNSClient::doUpdate.
Definition: dns_client.cc:308
isc::d2::DNSClient::Status
Status
A status code of the DNSClient.
Definition: dns_client.h:58
isc::d2::DNSClient::IO_STOPPED
@ IO_STOPPED
IO was stopped.
Definition: dns_client.h:61
isc::d2::DNSClient::TIMEOUT
@ TIMEOUT
No response, timeout.
Definition: dns_client.h:60
isc::d2::DNSClient::OTHER
@ OTHER
Other, unclassified error.
Definition: dns_client.h:63
isc::d2::DNSClient::INVALID_RESPONSE
@ INVALID_RESPONSE
Response received but invalid.
Definition: dns_client.h:62
isc::d2::DNSClient::SUCCESS
@ SUCCESS
Response received and is ok.
Definition: dns_client.h:59
isc::d2::DNSClient::Protocol
Protocol
Transport layer protocol used by a DNS Client to communicate with a server.
Definition: dns_client.h:52
isc::d2::DNSClient::TCP
@ TCP
Definition: dns_client.h:54
isc::d2::DNSClient::UDP
@ UDP
Definition: dns_client.h:53
isc::dns::AbstractMessageRenderer::setBuffer
void setBuffer(isc::util::OutputBuffer *buffer)
Set or reset a temporary output buffer.
Definition: messagerenderer.cc:371
isc::dns::MessageRenderer
The MessageRenderer is a concrete derived class of AbstractMessageRenderer as a general purpose imple...
Definition: messagerenderer.h:357
isc::stats::StatsMgr
Statistics Manager class.
Definition: lib/stats/stats_mgr.h:63
isc::stats::StatsMgr::instance
static StatsMgr & instance()
Statistics Manager accessor method.
Definition: lib/stats/stats_mgr.cc:27
isc::stats::StatsMgr::generateName
static std::string generateName(const std::string &context, Type index, const std::string &stat_name)
Generates statistic name in a given context.
Definition: lib/stats/stats_mgr.h:282
isc::util::OutputBuffer
The OutputBuffer class is a buffer abstraction for manipulating mutable data.
Definition: buffer.h:294
d2_log.h
dns_client.h
isc_throw
#define isc_throw(type, stream)
A shortcut macro to insert known values into exception arguments.
Definition: exceptions/exceptions.h:210
isc::stats::StatsMgr::addValue
void addValue(const std::string &name, const int64_t value)
Records incremental integer observation.
Definition: lib/stats/stats_mgr.cc:77
stats_mgr.h
LOG_DEBUG
#define LOG_DEBUG(LOGGER, LEVEL, MESSAGE)
Macro to conveniently test debug output and log it.
Definition: macros.h:14
messagerenderer.h
isc::asiodns
Definition: asiodns_messages.cc:8
isc::asiolink
Definition: addr_utilities.cc:170
isc::d2::D2UpdateMessagePtr
boost::shared_ptr< D2UpdateMessage > D2UpdateMessagePtr
Pointer to the DNS Update Message.
Definition: d2_update_message.h:70
isc::d2::d2_to_dns_logger
isc::log::Logger d2_to_dns_logger("d2-to-dns")
Definition: d2_log.h:20
isc::d2::DHCP_DDNS_INVALID_RESPONSE
const isc::log::MessageID DHCP_DDNS_INVALID_RESPONSE
Definition: d2_messages.h:44
isc::d2::D2TsigKeyPtr
boost::shared_ptr< D2TsigKey > D2TsigKeyPtr
Type of pointer to a D2 TSIG key.
Definition: d2_tsig_key.h:71
isc::dns
Definition: dns_fwd.h:18
isc::dns::TSIGContextPtr
boost::shared_ptr< TSIGContext > TSIGContextPtr
Definition: tsig.h:435
isc::log::DBGLVL_TRACE_DETAIL
const int DBGLVL_TRACE_DETAIL
Trace detailed operations.
Definition: log_dbglevels.h:75
isc::stats
Definition: context.cc:18
isc::util
Definition: edns.h:19
isc::util::OutputBufferPtr
boost::shared_ptr< OutputBuffer > OutputBufferPtr
Definition: buffer.h:603
isc
Defines the logger used by the top-level component of kea-lfc.
Definition: agent_parser.cc:143