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1 : /*
2 : *
3 : * Copyright (c) 2020 Project CHIP Authors
4 : * All rights reserved.
5 : *
6 : * Licensed under the Apache License, Version 2.0 (the "License");
7 : * you may not use this file except in compliance with the License.
8 : * You may obtain a copy of the License at
9 : *
10 : * http://www.apache.org/licenses/LICENSE-2.0
11 : *
12 : * Unless required by applicable law or agreed to in writing, software
13 : * distributed under the License is distributed on an "AS IS" BASIS,
14 : * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 : * See the License for the specific language governing permissions and
16 : * limitations under the License.
17 : */
18 : #pragma once
19 :
20 : #include <access/SubjectDescriptor.h>
21 : #include <app/ConcreteCommandPath.h>
22 : #include <app/data-model/EncodableToTLV.h>
23 : #include <app/data-model/Encode.h>
24 : #include <app/data-model/FabricScoped.h>
25 : #include <lib/core/CHIPCore.h>
26 : #include <lib/support/CodeUtils.h>
27 : #include <lib/support/IntrusiveList.h>
28 : #include <lib/support/logging/CHIPLogging.h>
29 : #include <messaging/ExchangeContext.h>
30 : #include <protocols/interaction_model/StatusCode.h>
31 :
32 : namespace chip {
33 : namespace app {
34 :
35 : /**
36 : * A handler for incoming Invoke interactions. This handles incoming Invoke
37 : * Request messages and generates Invoke Response messages.
38 : *
39 : * Allows adding responses (status, or server to client command) to be sent in
40 : * the Invoke Response message: see the various "Add*" methods.
41 : *
42 : * Allows adding the responses asynchronously when using `CommandHandler::Handle`
43 : * (see documentation for `CommandHandler::Handle` for details)
44 : *
45 : * Upgrading notes: this class has moved to an interface from a previous more complex
46 : * implementation. If upgrading code between versions, please see docs/upgrading.md
47 : */
48 : class CommandHandler
49 : {
50 : public:
51 65 : virtual ~CommandHandler() = default;
52 :
53 : /**
54 : * Class that allows asynchronous command processing before sending a
55 : * response. When such processing is desired:
56 : *
57 : * 1) Create a Handle initialized with the CommandHandler that delivered the
58 : * incoming command.
59 : * 2) Ensure the Handle, or some Handle it's moved into via the move
60 : * constructor or move assignment operator, remains alive during the
61 : * course of the asynchronous processing.
62 : * 3) Ensure that the ConcreteCommandPath involved will be known when
63 : * sending the response.
64 : * 4) When ready to send the response:
65 : * * Ensure that no other Matter tasks are running in parallel (e.g. by
66 : * running on the Matter event loop or holding the Matter stack lock).
67 : * * Call Get() to get the CommandHandler.
68 : * * Check that Get() did not return null.
69 : * * Add the response to the CommandHandler via one of the Add* methods.
70 : * * Let the Handle get destroyed, or manually call Handle::Release() if
71 : * destruction of the Handle is not desirable for some reason.
72 : *
73 : * The Invoke Response will not be sent until all outstanding Handles have
74 : * been destroyed or have had Release called.
75 : */
76 : class Handle : public IntrusiveListNodeBase<>
77 : {
78 : public:
79 : Handle() {}
80 : Handle(const Handle & handle) = delete;
81 : Handle(Handle && handle)
82 : {
83 : Init(handle.mpHandler);
84 : handle.Release();
85 : }
86 : Handle(decltype(nullptr)) {}
87 : Handle(CommandHandler * handler);
88 48 : ~Handle() { Release(); }
89 :
90 : Handle & operator=(Handle && handle)
91 : {
92 : Release();
93 : Init(handle.mpHandler);
94 :
95 : handle.Release();
96 : return *this;
97 : }
98 :
99 : Handle & operator=(decltype(nullptr))
100 : {
101 : Release();
102 : return *this;
103 : }
104 :
105 : /**
106 : * Get the CommandHandler object it holds. Get() may return a nullptr if the CommandHandler object it holds is no longer
107 : * valid.
108 : */
109 : CommandHandler * Get();
110 :
111 : bool IsValid() const { return mpHandler != nullptr; }
112 :
113 : void Release();
114 :
115 103 : void Invalidate() { mpHandler = nullptr; }
116 :
117 : private:
118 : void Init(CommandHandler * handler);
119 :
120 : CommandHandler * mpHandler = nullptr;
121 : };
122 :
123 : /**
124 : * Adds the given command status and returns any failures in adding statuses (e.g. out
125 : * of buffer space) to the caller. `context` is an optional (if not nullptr)
126 : * debug string to include in logging.
127 : */
128 : virtual CHIP_ERROR FallibleAddStatus(const ConcreteCommandPath & aRequestCommandPath,
129 : const Protocols::InteractionModel::ClusterStatusCode & aStatus,
130 : const char * context = nullptr) = 0;
131 20 : CHIP_ERROR FallibleAddStatus(const ConcreteCommandPath & aRequestCommandPath, const Protocols::InteractionModel::Status aStatus,
132 : const char * context = nullptr)
133 : {
134 20 : return FallibleAddStatus(aRequestCommandPath, Protocols::InteractionModel::ClusterStatusCode{ aStatus }, context);
135 : }
136 :
137 : /**
138 : * Adds an IM global or Cluster status when the caller is unable to handle any failures. Logging is performed
139 : * and failure to register the status is checked with VerifyOrDie. `context` is an optional (if not nullptr)
140 : * debug string to include in logging.
141 : */
142 : virtual void AddStatus(const ConcreteCommandPath & aRequestCommandPath,
143 : const Protocols::InteractionModel::ClusterStatusCode & aStatus, const char * context = nullptr) = 0;
144 0 : void AddStatus(const ConcreteCommandPath & aRequestCommandPath, const Protocols::InteractionModel::Status aStatus,
145 : const char * context = nullptr)
146 : {
147 0 : AddStatus(aRequestCommandPath, Protocols::InteractionModel::ClusterStatusCode{ aStatus }, context);
148 0 : }
149 :
150 : /**
151 : * Sets the response to indicate Success with a cluster-specific status code `aClusterStatus` included.
152 : *
153 : * NOTE: For regular success, what you want is AddStatus/FailibleAddStatus(aRequestCommandPath,
154 : * InteractionModel::Status::Success).
155 : */
156 0 : virtual CHIP_ERROR AddClusterSpecificSuccess(const ConcreteCommandPath & aRequestCommandPath, ClusterStatus aClusterStatus)
157 : {
158 0 : return FallibleAddStatus(aRequestCommandPath,
159 0 : Protocols::InteractionModel::ClusterStatusCode::ClusterSpecificSuccess(aClusterStatus));
160 : }
161 :
162 : /**
163 : * Sets the response to indicate Failure with a cluster-specific status code `aClusterStatus` included.
164 : */
165 0 : virtual CHIP_ERROR AddClusterSpecificFailure(const ConcreteCommandPath & aRequestCommandPath, ClusterStatus aClusterStatus)
166 : {
167 0 : return FallibleAddStatus(aRequestCommandPath,
168 0 : Protocols::InteractionModel::ClusterStatusCode::ClusterSpecificFailure(aClusterStatus));
169 : }
170 :
171 : /**
172 : * GetAccessingFabricIndex() may only be called during synchronous command
173 : * processing. Anything that runs async (while holding a
174 : * CommandHandler::Handle or equivalent) must not call this method, because
175 : * it will not work right if the session we're using was evicted.
176 : */
177 : virtual FabricIndex GetAccessingFabricIndex() const = 0;
178 :
179 : /**
180 : * API for adding a data response. The `aEncodable` is generally expected to encode
181 : * a ClusterName::Commands::CommandName::Type struct, however any object should work.
182 : *
183 : * @param [in] aRequestCommandPath the concrete path of the command we are
184 : * responding to.
185 : * @param [in] aResponseCommandId the command whose content is being encoded.
186 : * @param [in] aEncodable - an encodable that places the command data structure
187 : * for `aResponseCommandId` into a TLV Writer.
188 : *
189 : * If you have no great way of handling the returned CHIP_ERROR, consider
190 : * using `AddResponse` which will automatically reply with `Failure` in
191 : * case AddResponseData fails.
192 : */
193 : virtual CHIP_ERROR AddResponseData(const ConcreteCommandPath & aRequestCommandPath, CommandId aResponseCommandId,
194 : const DataModel::EncodableToTLV & aEncodable) = 0;
195 :
196 : /**
197 : * Attempts to encode a response to a command.
198 : *
199 : * `aRequestCommandPath` represents the request path (endpoint/cluster/commandid) and the reply
200 : * will preserve the same path and switch the command id to aResponseCommandId.
201 : *
202 : * As this command does not return any error codes, it must try its best to encode the reply
203 : * and if it fails, it MUST encode a `Protocols::InteractionModel::Status::Failure` as a
204 : * reply (i.e. a reply is guaranteed to be sent).
205 : *
206 : * Above is the main difference from AddResponseData: AddResponse will auto-reply with failure while
207 : * AddResponseData allows the caller to try to deal with any CHIP_ERRORs.
208 : */
209 : virtual void AddResponse(const ConcreteCommandPath & aRequestCommandPath, CommandId aResponseCommandId,
210 : const DataModel::EncodableToTLV & aEncodable) = 0;
211 :
212 : /**
213 : * Check whether the InvokeRequest we are handling is a timed invoke.
214 : */
215 : virtual bool IsTimedInvoke() const = 0;
216 :
217 : /**
218 : * @brief Flush acks right away for a slow command
219 : *
220 : * Some commands that do heavy lifting of storage/crypto should
221 : * ack right away to improve reliability and reduce needless retries. This
222 : * method can be manually called in commands that are especially slow to
223 : * immediately schedule an acknowledgement (if needed) since the delayed
224 : * stand-alone ack timer may actually not hit soon enough due to blocking command
225 : * execution.
226 : *
227 : */
228 : virtual void FlushAcksRightAwayOnSlowCommand() = 0;
229 :
230 : virtual Access::SubjectDescriptor GetSubjectDescriptor() const = 0;
231 :
232 : /**
233 : * Gets the inner exchange context object, without ownership.
234 : *
235 : * WARNING: This is dangerous, since it is directly interacting with the
236 : * exchange being managed automatically by mpResponder and
237 : * if not done carefully, may end up with use-after-free errors.
238 : *
239 : * @return The inner exchange context, might be nullptr if no
240 : * exchange context has been assigned or the context
241 : * has been released.
242 : */
243 : virtual Messaging::ExchangeContext * GetExchangeContext() const = 0;
244 :
245 : /**
246 : * API for adding a data response. The template parameter T is generally
247 : * expected to be a ClusterName::Commands::CommandName::Type struct, but any
248 : * object that can be encoded using the DataModel::Encode machinery and
249 : * exposes the right command id will work.
250 : *
251 : * If you have no great way of handling the returned CHIP_ERROR, consider
252 : * using `AddResponse` which will automatically reply with `Failure` in
253 : * case AddResponseData fails.
254 : *
255 : * @param [in] aRequestCommandPath the concrete path of the command we are
256 : * responding to.
257 : *
258 : * The response path will be the same as the request, except the
259 : * reply command ID used will be `CommandData::GetCommandId()` assumed
260 : * to be a member of the templated type
261 : *
262 : * @param [in] aData the data for the response. It is expected to provide
263 : * `GetCommandData` as a STATIC on its type as well as encode the
264 : * correct data structure for building a reply.
265 : */
266 : template <typename CommandData>
267 : CHIP_ERROR AddResponseData(const ConcreteCommandPath & aRequestCommandPath, const CommandData & aData)
268 : {
269 : EncodableResponseCommandPayload<CommandData> encoder(aData);
270 : return AddResponseData(aRequestCommandPath, CommandData::GetCommandId(), encoder);
271 : }
272 :
273 : /**
274 : * API for adding a response. This will try to encode a data response (response command), and if that fails
275 : * it will encode a Protocols::InteractionModel::Status::Failure status response instead.
276 : *
277 : * Above is the main difference from AddResponseData: AddResponse will auto-reply with failure while
278 : * AddResponseData allows the caller to try to deal with any CHIP_ERRORs.
279 : *
280 : * The template parameter T is generally expected to be a ClusterName::Commands::CommandName::Type struct, but any object that
281 : * can be encoded using the DataModel::Encode machinery and exposes the right command id will work.
282 : *
283 : * Since the function will call AddStatus when it fails to encode the data, it cannot send any response when it fails to encode
284 : * a status code since another AddStatus call will also fail. The error from AddStatus will just be logged.
285 : *
286 : * @param [in] aRequestCommandPath the concrete path of the command we are
287 : * responding to.
288 : * @param [in] aData the data for the response.
289 : */
290 : template <typename CommandData>
291 : void AddResponse(const ConcreteCommandPath & aRequestCommandPath, const CommandData & aData)
292 : {
293 : EncodableResponseCommandPayload<CommandData> encodable(aData);
294 : AddResponse(aRequestCommandPath, CommandData::GetCommandId(), encodable);
295 : }
296 :
297 : protected:
298 : // Encoding a response command payload requires a fabric index, in general,
299 : // because any fabric-scoped fields in the payload need it to deal with
300 : // their fabric-sensitive fields.
301 : template <typename CommandData>
302 : class EncodableResponseCommandPayload : public DataModel::EncodableToTLV
303 : {
304 : public:
305 : EncodableResponseCommandPayload(const CommandData & value) : mValue(value) {}
306 :
307 : CHIP_ERROR EncodeTo(DataModel::FabricAwareTLVWriter & writer, TLV::Tag tag) const final
308 : {
309 : return DataModel::EncodeResponseCommandPayload(writer, tag, mValue);
310 : }
311 :
312 : CHIP_ERROR EncodeTo(TLV::TLVWriter & writer, TLV::Tag tag) const final
313 : {
314 : // Not used, keep it as small as we can.
315 : return CHIP_ERROR_INCORRECT_STATE;
316 : }
317 :
318 : private:
319 : const CommandData & mValue;
320 : };
321 :
322 : /**
323 : * IncrementHoldOff will increase the inner refcount of the CommandHandler.
324 : *
325 : * Users should use CommandHandler::Handle for management the lifespan of the CommandHandler.
326 : * DefRef should be released in reasonable time, and Close() should only be called when the refcount reached 0.
327 : */
328 0 : virtual void IncrementHoldOff(Handle * apHandle) {}
329 :
330 : /**
331 : * DecrementHoldOff is used by CommandHandler::Handle for decreasing the refcount of the CommandHandler.
332 : * When refcount reached 0, CommandHandler will send the response to the peer and shutdown.
333 : */
334 0 : virtual void DecrementHoldOff(Handle * apHandle) {}
335 : };
336 :
337 : } // namespace app
338 : } // namespace chip
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