Line data Source code
1 : /*
2 : *
3 : * Copyright (c) 2020-2021 Project CHIP Authors
4 : * Copyright (c) 2016-2017 Nest Labs, Inc.
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 :
19 : /**
20 : * @file
21 : * This file defines the chip::System::PacketBuffer class,
22 : * which provides the mechanisms for manipulating packets of *
23 : * octet-serialized data.
24 : */
25 :
26 : #pragma once
27 :
28 : // Include configuration header
29 : #include <system/SystemPacketBufferInternal.h>
30 :
31 : // Include dependent headers
32 : #include <lib/support/BufferWriter.h>
33 : #include <lib/support/CodeUtils.h>
34 : #include <lib/support/DLLUtil.h>
35 : #include <system/SystemAlignSize.h>
36 : #include <system/SystemError.h>
37 :
38 : #include <stddef.h>
39 : #include <utility>
40 :
41 : #if CHIP_SYSTEM_CONFIG_USE_LWIP
42 : #include <lwip/mem.h>
43 : #include <lwip/memp.h>
44 : #include <lwip/pbuf.h>
45 : #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
46 :
47 : namespace chip {
48 : namespace System {
49 :
50 : class PacketBufferHandle;
51 :
52 : #if !CHIP_SYSTEM_CONFIG_USE_LWIP
53 : struct pbuf
54 : {
55 : struct pbuf * next;
56 : void * payload;
57 : size_t tot_len;
58 : size_t len;
59 : uint16_t ref;
60 : #if CHIP_SYSTEM_PACKETBUFFER_FROM_CHIP_HEAP
61 : size_t alloc_size;
62 : #endif
63 : };
64 : #endif // !CHIP_SYSTEM_CONFIG_USE_LWIP
65 :
66 : /** @class PacketBuffer
67 : *
68 : * @brief
69 : * The packet buffer class is the core structure used for manipulating packets of octet-serialized data, usually in the
70 : * context of a data communications network, like Bluetooth or the Internet protocol.
71 : *
72 : * In LwIP-based environments, this class is built on top of the pbuf structure defined in that library. In the absence of
73 : * LwIP, chip provides either a malloc-based implementation, or a pool-based implementation that closely approximates the
74 : * memory challenges of deeply embedded devices.
75 : *
76 : * The PacketBuffer class, like many similar structures used in layered network stacks, provide a mechanism to reserve space
77 : * for protocol headers at each layer of a configurable communication stack. For details, see `PacketBufferHandle::New()`
78 : * as well as LwIP documentation.
79 : *
80 : * PacketBuffer objects are reference-counted, and normally held and used through a PacketBufferHandle that owns one of the
81 : * counted references. When a PacketBufferHandle goes out of scope, its reference is released. To take ownership, a function
82 : * takes a PacketBufferHandle by value. To borrow ownership, a function takes a `const PacketBufferHandle &`.
83 : *
84 : * New objects of PacketBuffer class are initialized at the beginning of an allocation of memory obtained from the underlying
85 : * environment, e.g. from LwIP pbuf target pools, from the standard C library heap, from an internal buffer pool. In the
86 : * simple pool case, the size of the data buffer is PacketBuffer::kBlockSize.
87 : *
88 : * PacketBuffer objects may be chained to accommodate larger payloads. Chaining, however, is not transparent, and users of the
89 : * class must explicitly decide to support chaining. Examples of classes written with chaining support are as follows:
90 : *
91 : * @ref chip::TLVReader
92 : * @ref chip::TLVWriter
93 : *
94 : * ### PacketBuffer format
95 : *
96 : * <pre>
97 : * ┌────────────────────────────────────┐
98 : * │ ┌────────────────────┐ │
99 : * │ │ │◁──────┴───────▷│
100 : * ┏━━━━━━━━┿━━━━━━━┿━┳━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━┓
101 : * ┃ pbuf len payload ┃ reserve ┃ data ┃ unused ┃
102 : * ┗━━━━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━━━━┻━━━━━━━━━━━━━━━━━━━━━━━━━┛
103 : * │ │← ReservedSize() →│← DataLength() →│← AvailableDataLength() →│
104 : * │ │ │← MaxDataLength() → · · · · · · · · · · ·→│
105 : * │ │ Start() │
106 : * │← kStructureSize →│← AllocSize() → · · · · · · · · · · · · · · · · · · · · · · →│
107 : * </pre>
108 : *
109 : */
110 : class DLL_EXPORT PacketBuffer : private pbuf
111 : {
112 : private:
113 : // The effective size of the packet buffer structure.
114 : #if CHIP_SYSTEM_CONFIG_USE_LWIP
115 : static constexpr size_t kStructureSize = LWIP_MEM_ALIGN_SIZE(sizeof(struct ::pbuf));
116 : #else // CHIP_SYSTEM_CONFIG_USE_LWIP
117 : static constexpr size_t kStructureSize = CHIP_SYSTEM_ALIGN_SIZE(sizeof(::chip::System::pbuf), 4u);
118 : #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
119 :
120 : public:
121 : /**
122 : * The maximum size of a regular buffer an application can allocate with no protocol header reserve.
123 : */
124 : #if CHIP_SYSTEM_CONFIG_USE_LWIP
125 : static constexpr size_t kMaxSizeWithoutReserve = LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE);
126 : #else
127 : static constexpr size_t kMaxSizeWithoutReserve = CHIP_SYSTEM_CONFIG_PACKETBUFFER_CAPACITY_MAX;
128 : #endif
129 :
130 : /**
131 : * The number of bytes to reserve in a network packet buffer to contain all the possible protocol encapsulation headers
132 : * before the application data.
133 : */
134 : static constexpr uint16_t kDefaultHeaderReserve = CHIP_SYSTEM_CONFIG_HEADER_RESERVE_SIZE;
135 :
136 : /**
137 : * The maximum size of a regular buffer an application can allocate with the default protocol header reserve.
138 : */
139 : static constexpr size_t kMaxSize = kMaxSizeWithoutReserve - kDefaultHeaderReserve;
140 :
141 : /**
142 : * The maximum size of a large buffer(> IPv6 MTU) that an application can allocate with no protocol header reserve.
143 : */
144 : static constexpr size_t kLargeBufMaxSizeWithoutReserve = CHIP_SYSTEM_CONFIG_MAX_LARGE_BUFFER_SIZE_BYTES;
145 :
146 : /**
147 : * The maximum size of a large buffer(> IPv6 MTU) that an application can allocate with the default protocol header reserve.
148 : */
149 : static constexpr size_t kLargeBufMaxSize = kLargeBufMaxSizeWithoutReserve - kDefaultHeaderReserve;
150 :
151 : /**
152 : * Unified constant(both regular and large buffers) for the maximum size that an application can allocate with no
153 : * protocol header reserve.
154 : */
155 : #if INET_CONFIG_ENABLE_TCP_ENDPOINT
156 : static constexpr size_t kMaxAllocSize = kLargeBufMaxSizeWithoutReserve;
157 : #else
158 : static constexpr size_t kMaxAllocSize = kMaxSizeWithoutReserve;
159 : #endif // INET_CONFIG_ENABLE_TCP_ENDPOINT
160 :
161 : /**
162 : * Return the size of the allocation including the reserved and payload data spaces but not including space
163 : * allocated for the PacketBuffer structure.
164 : *
165 : * @note The allocation size is equal to or greater than the \c aAllocSize parameter to the \c Create method).
166 : *
167 : * @return size of the allocation
168 : */
169 128034 : size_t AllocSize() const
170 : {
171 : #if CHIP_SYSTEM_PACKETBUFFER_FROM_LWIP_STANDARD_POOL || CHIP_SYSTEM_PACKETBUFFER_FROM_CHIP_POOL
172 : return kMaxSizeWithoutReserve;
173 : #elif CHIP_SYSTEM_PACKETBUFFER_FROM_CHIP_HEAP
174 128034 : return this->alloc_size;
175 : #elif CHIP_SYSTEM_PACKETBUFFER_FROM_LWIP_CUSTOM_POOL
176 : // Temporary workaround for custom pbufs by assuming size to be PBUF_POOL_BUFSIZE
177 : if (this->flags & PBUF_FLAG_IS_CUSTOM)
178 : return LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE) - kStructureSize;
179 : else
180 : return LWIP_MEM_ALIGN_SIZE(memp_sizes[this->pool]) - kStructureSize;
181 : #else
182 : #error "Unimplemented PacketBuffer storage case"
183 : #endif
184 : }
185 :
186 : /**
187 : * Get a pointer to the start of data in a buffer.
188 : *
189 : * @return pointer to the start of data.
190 : */
191 369031 : uint8_t * Start() const { return static_cast<uint8_t *>(this->payload); }
192 :
193 : /**
194 : * Set the the start of data in a buffer, adjusting length and total length accordingly.
195 : *
196 : * @note The data within the buffer is not moved, only accounting information is changed. The function is commonly used to
197 : * either strip or prepend protocol headers in a zero-copy way.
198 : *
199 : * @note This call should not be used on any buffer that is not the head of a buffer chain, as it only alters the current
200 : * buffer.
201 : *
202 : * @param[in] aNewStart - A pointer to where the new payload should start. newStart will be adjusted internally to fall within
203 : * the boundaries of the first buffer in the PacketBuffer chain.
204 : */
205 : void SetStart(uint8_t * aNewStart);
206 :
207 : /**
208 : * Get the length, in bytes, of data in a packet buffer.
209 : *
210 : * @return length, in bytes (current payload length).
211 : */
212 163364 : size_t DataLength() const { return this->len; }
213 :
214 : /**
215 : * Set the length, in bytes, of data in a packet buffer, adjusting total length accordingly.
216 : *
217 : * The function sets the length, in bytes, of the data in the buffer, adjusting the total length appropriately. When the buffer
218 : * is not the head of the buffer chain (common case: the caller adds data to the last buffer in the PacketBuffer chain prior to
219 : * calling higher layers), the aChainHead __must__ be passed in to properly adjust the total lengths of each buffer ahead of
220 : * the current buffer.
221 : *
222 : * @param[in] aNewLen - new length, in bytes, of this buffer.
223 : *
224 : * @param[in,out] aChainHead - the head of the buffer chain the current buffer belongs to. May be \c nullptr if the current
225 : * buffer is the head of the buffer chain.
226 : */
227 : void SetDataLength(size_t aNewLen, const PacketBufferHandle & aChainHead);
228 19912 : void SetDataLength(size_t aNewLen) { SetDataLength(aNewLen, nullptr); }
229 :
230 : /**
231 : * Get the total length of packet data in the buffer chain.
232 : *
233 : * @return total length, in octets.
234 : */
235 53841 : size_t TotalLength() const { return this->tot_len; }
236 :
237 : /**
238 : * Get the maximum amount, in bytes, of data that will fit in the buffer given the current start position and buffer size.
239 : *
240 : * @return number of bytes that fits in the buffer given the current start position.
241 : */
242 : size_t MaxDataLength() const;
243 :
244 : /**
245 : * Get the number of bytes of data that can be added to the current buffer given the current start position and data length.
246 : *
247 : * @return the length, in bytes, of data that will fit in the current buffer given the current start position and data length.
248 : */
249 : size_t AvailableDataLength() const;
250 :
251 : /**
252 : * Get the number of bytes within the current buffer between the start of the buffer and the current data start position.
253 : *
254 : * @return the amount, in bytes, of space between the start of the buffer and the current data start position.
255 : */
256 : uint16_t ReservedSize() const;
257 :
258 : /**
259 : * Determine whether there are any additional buffers chained to the current buffer.
260 : *
261 : * @return \c true if there is a chained buffer.
262 : */
263 41060 : bool HasChainedBuffer() const { return ChainedBuffer() != nullptr; }
264 :
265 : /**
266 : * Add the given packet buffer to the end of the buffer chain, adjusting the total length of each buffer in the chain
267 : * accordingly.
268 : *
269 : * @note The current packet buffer must be the head of the buffer chain for the lengths to be adjusted properly.
270 : *
271 : * @note Ownership is transferred from the argument to the `next` link at the end of the current chain.
272 : *
273 : * @param[in] aPacket - the packet buffer to be added to the end of the current chain.
274 : */
275 : void AddToEnd(PacketBufferHandle && aPacket);
276 :
277 : /**
278 : * Move data from subsequent buffers in the chain into the current buffer until it is full.
279 : *
280 : * Only the current buffer is compacted: the data within the current buffer is moved to the front of the buffer, eliminating
281 : * any reserved space. The remaining available space is filled with data moved from subsequent buffers in the chain, until the
282 : * current buffer is full. If a subsequent buffer in the chain is moved into the current buffer in its entirety, it is removed
283 : * from the chain and freed. The method takes no parameters, returns no results and cannot fail.
284 : */
285 : void CompactHead();
286 :
287 : /**
288 : * Adjust the current buffer to indicate the amount of data consumed.
289 : *
290 : * Advance the data start position in the current buffer by the specified amount, in bytes, up to the length of data in the
291 : * buffer. Decrease the length and total length by the amount consumed.
292 : *
293 : * @param[in] aConsumeLength - number of bytes to consume from the current buffer.
294 : */
295 : void ConsumeHead(size_t aConsumeLength);
296 :
297 : /**
298 : * Ensure the buffer has at least the specified amount of reserved space.
299 : *
300 : * Ensure the buffer has at least the specified amount of reserved space, moving the data in the buffer forward to make room if
301 : * necessary.
302 : *
303 : * @param[in] aReservedSize - number of bytes desired for the headers.
304 : *
305 : * @return \c true if the requested reserved size is available, \c false if there's not enough room in the buffer.
306 : */
307 : CHECK_RETURN_VALUE bool EnsureReservedSize(uint16_t aReservedSize);
308 :
309 : /**
310 : * Align the buffer payload on the specified bytes boundary.
311 : *
312 : * Moving the payload in the buffer forward if necessary.
313 : *
314 : * @param[in] aAlignBytes - specifies number of bytes alignment for the payload start pointer.
315 : *
316 : * @return \c true if alignment is successful, \c false if there's not enough room in the buffer.
317 : */
318 : bool AlignPayload(uint16_t aAlignBytes);
319 :
320 : /**
321 : * Return the next buffer in a buffer chain.
322 : *
323 : * If there is no next buffer, the handle will have \c IsNull() \c true.
324 : *
325 : * @return a handle to the next buffer in the buffer chain.
326 : */
327 : CHECK_RETURN_VALUE PacketBufferHandle Next();
328 :
329 : /**
330 : * Return the last buffer in a buffer chain.
331 : *
332 : * @return a handle to the last buffer in the buffer chain.
333 : */
334 : CHECK_RETURN_VALUE PacketBufferHandle Last();
335 :
336 : /**
337 : * Copies data from the payloads of a chain of packet buffers until a given amount of data has been copied.
338 : *
339 : * @param[in] buf Destination buffer; must be at least @a length bytes.
340 : * @param[in] length Destination buffer length.
341 : *
342 : * @retval #CHIP_ERROR_BUFFER_TOO_SMALL If the total length of the payloads in the chain is less than the requested @a length.
343 : * @retval #CHIP_ERROR_INTERNAL In case of an inconsistency in the buffer chain.
344 : * @retval #CHIP_NO_ERROR If the requested payload has been copied.
345 : */
346 : CHIP_ERROR Read(uint8_t * buf, size_t length) const;
347 : template <size_t N>
348 13 : inline CHIP_ERROR Read(uint8_t (&buf)[N]) const
349 : {
350 13 : return Read(buf, N);
351 : }
352 :
353 : /**
354 : * Perform an implementation-defined check on the validity of a PacketBuffer pointer.
355 : *
356 : * Unless enabled by #CHIP_CONFIG_MEMORY_DEBUG_CHECKS == 1, this function does nothing.
357 : *
358 : * When enabled, it performs an implementation- and configuration-defined check on
359 : * the validity of the packet buffer. It MAY log an error and/or abort the program
360 : * if the packet buffer or the implementation-defined memory management system is in
361 : * a faulty state. (Some configurations may not actually perform any check.)
362 : *
363 : * @note A null pointer is not considered faulty.
364 : *
365 : * @param[in] buffer - the packet buffer to check.
366 : */
367 45816 : static void Check(const PacketBuffer * buffer)
368 : {
369 : #if CHIP_SYSTEM_PACKETBUFFER_HAS_CHECK
370 : InternalCheck(buffer);
371 : #endif
372 45816 : }
373 :
374 : private:
375 : // Memory required for a maximum-size PacketBuffer.
376 : static constexpr uint16_t kBlockSize = PacketBuffer::kStructureSize + PacketBuffer::kMaxSizeWithoutReserve;
377 :
378 : // Note: this condition includes DOXYGEN to work around a Doxygen error. DOXYGEN is never defined in any actual build.
379 : #if CHIP_SYSTEM_PACKETBUFFER_FROM_CHIP_POOL || defined(DOXYGEN)
380 : typedef union
381 : {
382 : pbuf Header;
383 : uint8_t Block[PacketBuffer::kBlockSize];
384 : } BufferPoolElement;
385 : static BufferPoolElement sBufferPool[CHIP_SYSTEM_CONFIG_PACKETBUFFER_POOL_SIZE];
386 : static PacketBuffer * sFreeList;
387 : static PacketBuffer * BuildFreeList();
388 : #endif // CHIP_SYSTEM_PACKETBUFFER_FROM_CHIP_POOL || defined(DOXYGEN)
389 :
390 : #if CHIP_SYSTEM_PACKETBUFFER_HAS_CHECK
391 : static void InternalCheck(const PacketBuffer * buffer);
392 : #endif
393 :
394 : void AddRef();
395 : bool HasSoleOwnership() const { return (this->ref == 1); }
396 : static void Free(PacketBuffer * aPacket);
397 : static PacketBuffer * FreeHead(PacketBuffer * aPacket);
398 :
399 122090 : PacketBuffer * ChainedBuffer() const { return static_cast<PacketBuffer *>(this->next); }
400 : PacketBuffer * Consume(size_t aConsumeLength);
401 : void Clear();
402 : void SetDataLength(size_t aNewLen, PacketBuffer * aChainHead);
403 :
404 : /**
405 : * Get a pointer to the start of the reserved space (which comes before the
406 : * payload). The actual reserved space is the ReservedSize() bytes starting
407 : * at this pointer.
408 : */
409 : uint8_t * ReserveStart();
410 : const uint8_t * ReserveStart() const;
411 :
412 : friend class PacketBufferHandle;
413 : friend class TestSystemPacketBuffer;
414 : };
415 :
416 : static_assert(sizeof(pbuf) == sizeof(PacketBuffer), "PacketBuffer must not have additional members");
417 :
418 : /**
419 : * @class PacketBufferHandle
420 : *
421 : * @brief
422 : * Tracks ownership of a PacketBuffer.
423 : *
424 : * PacketBuffer objects are reference-counted, and normally held and used through a PacketBufferHandle that owns one of the
425 : * counted references. When a PacketBufferHandle goes out of scope, its reference is released. To take ownership, a function
426 : * takes a PacketBufferHandle by value. To borrow ownership, a function takes a `const PacketBufferHandle &`.
427 : */
428 : class DLL_EXPORT PacketBufferHandle
429 : {
430 : public:
431 : /**
432 : * Construct an empty PacketBufferHandle.
433 : */
434 1 : PacketBufferHandle() : mBuffer(nullptr) {}
435 22264 : PacketBufferHandle(decltype(nullptr)) : mBuffer(nullptr) {}
436 :
437 : /**
438 : * Construct a PacketBufferHandle that takes ownership of a PacketBuffer from another.
439 : */
440 68876 : PacketBufferHandle(PacketBufferHandle && aOther)
441 68876 : {
442 68876 : mBuffer = aOther.mBuffer;
443 68876 : aOther.mBuffer = nullptr;
444 68876 : }
445 :
446 1 : ~PacketBufferHandle() { *this = nullptr; }
447 :
448 : /**
449 : * Take ownership of a PacketBuffer from another PacketBufferHandle, freeing any existing owned buffer.
450 : */
451 79661 : PacketBufferHandle & operator=(PacketBufferHandle && aOther)
452 : {
453 79661 : if (mBuffer != nullptr)
454 : {
455 30 : PacketBuffer::Free(mBuffer);
456 : }
457 79661 : mBuffer = aOther.mBuffer;
458 79661 : aOther.mBuffer = nullptr;
459 79661 : return *this;
460 : }
461 :
462 : /**
463 : * Free any buffer owned by this handle.
464 : */
465 1 : PacketBufferHandle & operator=(decltype(nullptr))
466 : {
467 1 : if (mBuffer != nullptr)
468 : {
469 0 : PacketBuffer::Free(mBuffer);
470 : }
471 1 : mBuffer = nullptr;
472 1 : return *this;
473 : }
474 :
475 : /**
476 : * Get a new handle to an existing buffer.
477 : *
478 : * @return a PacketBufferHandle that shares ownership with this.
479 : */
480 23916 : PacketBufferHandle Retain() const
481 : {
482 23916 : mBuffer->AddRef();
483 23916 : return PacketBufferHandle(mBuffer);
484 : }
485 :
486 : /**
487 : * Access a PackerBuffer's public methods.
488 : */
489 471813 : PacketBuffer * operator->() const { return mBuffer; }
490 :
491 : /**
492 : * Test whether this PacketBufferHandle is empty, or conversely owns a PacketBuffer.
493 : *
494 : * @return \c true if this PacketBufferHandle is empty; return \c false if it owns a PacketBuffer.
495 : */
496 86969 : bool IsNull() const { return mBuffer == nullptr; }
497 :
498 : /**
499 : * Test whether the PacketBuffer owned by this PacketBufferHandle has unique ownership.
500 : *
501 : * @return \c true if the PacketBuffer owned by this PacketBufferHandle is solely owned; return \c false if
502 : * it has more than one ownership.
503 : */
504 : bool HasSoleOwnership() const { return mBuffer->HasSoleOwnership(); }
505 :
506 : /**
507 : * Detach and return the head of a buffer chain while updating this handle to point to the remaining buffers.
508 : * The current buffer must be the head of the chain.
509 : *
510 : * This PacketBufferHandle now holds the ownership formerly held by the head of the chain.
511 : * The returned PacketBufferHandle holds the ownership formerly held by this.
512 : *
513 : * @return the detached buffer formerly at the head of the buffer chain.
514 : */
515 : CHECK_RETURN_VALUE PacketBufferHandle PopHead();
516 :
517 : /**
518 : * Free the first buffer in a chain.
519 : *
520 : * @note When the buffer chain is referenced by multiple handles, `FreeHead()` will detach the head, but will not forcibly
521 : * deallocate the head buffer.
522 : */
523 7 : void FreeHead()
524 : {
525 : // `PacketBuffer::FreeHead()` frees the current head; this takes ownership from the `next` link.
526 7 : mBuffer = PacketBuffer::FreeHead(mBuffer);
527 7 : }
528 :
529 : /**
530 : * Add the given packet buffer to the end of the buffer chain, adjusting the total length of each buffer in the chain
531 : * accordingly.
532 : *
533 : * @note The current packet buffer handle must either be the head of the buffer chain for the lengths to be adjusted properly,
534 : * or be null (in which case it becomes the head).
535 : *
536 : * @note Ownership is transferred from the argument to the `next` link at the end of the current chain,
537 : * or to the handle if it's currently null.
538 : *
539 : * @param[in] aPacket - the packet buffer to be added to the end of the current chain.
540 : */
541 1805 : void AddToEnd(PacketBufferHandle && aPacket)
542 : {
543 1805 : if (IsNull())
544 : {
545 493 : mBuffer = aPacket.mBuffer;
546 493 : aPacket.mBuffer = nullptr;
547 : }
548 : else
549 : {
550 1312 : mBuffer->AddToEnd(std::move(aPacket));
551 : }
552 1805 : }
553 :
554 : /**
555 : * Consume data in a chain of buffers.
556 : *
557 : * Consume data in a chain of buffers starting with the current buffer and proceeding through the remaining buffers in the
558 : * chain. Each buffer that is completely consumed is freed and the handle holds the first buffer (if any) containing the
559 : * remaining data. The current buffer must be the head of the buffer chain.
560 : *
561 : * @param[in] aConsumeLength - number of bytes to consume from the current chain.
562 : */
563 15 : void Consume(size_t aConsumeLength) { mBuffer = mBuffer->Consume(aConsumeLength); }
564 :
565 : /**
566 : * Copy the given buffer to a right-sized buffer if applicable.
567 : *
568 : * Only operates on single buffers (for chains, use \c CompactHead() and RightSize the tail).
569 : * Requires that this handle be the only reference to the underlying buffer.
570 : */
571 7709 : void RightSize()
572 : {
573 : #if CHIP_SYSTEM_PACKETBUFFER_HAS_RIGHTSIZE
574 7709 : InternalRightSize();
575 : #endif
576 7709 : }
577 :
578 : /**
579 : * Get a new handle to a raw PacketBuffer pointer.
580 : *
581 : * @brief The caller's ownership is transferred to this.
582 : *
583 : * @note This should only be used in low-level code, e.g. to import buffers from LwIP or a similar stack.
584 : */
585 : static PacketBufferHandle Adopt(PacketBuffer * buffer) { return PacketBufferHandle(buffer); }
586 : #if CHIP_SYSTEM_CONFIG_USE_LWIP
587 : static PacketBufferHandle Adopt(pbuf * buffer) { return Adopt(reinterpret_cast<PacketBuffer *>(buffer)); }
588 : #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
589 :
590 : /**
591 : * Advance this PacketBufferHandle to the next buffer in a chain.
592 : *
593 : * @note This differs from `FreeHead()` in that it does not touch any content in the currently referenced packet buffer;
594 : * it only changes which buffer this handle owns. (Note that this could result in the previous buffer being freed,
595 : * if there is no other owner.) `Advance()` is designed to be used with an additional handle to traverse a buffer chain,
596 : * whereas `FreeHead()` modifies a chain.
597 : */
598 0 : void Advance() { *this = Hold(mBuffer->ChainedBuffer()); }
599 :
600 : /**
601 : * Export a raw PacketBuffer pointer.
602 : *
603 : * @brief The PacketBufferHandle's ownership is transferred to the caller.
604 : *
605 : * @note This should only be used in low-level code. The caller owns one counted reference to the \c PacketBuffer
606 : * and is responsible for managing it safely.
607 : *
608 : * @note The ref-qualifier `&&` requires the caller to use `std::move` to emphasize that ownership is
609 : * moved out of this handle.
610 : */
611 1709 : CHECK_RETURN_VALUE PacketBuffer * UnsafeRelease() &&
612 : {
613 1709 : PacketBuffer::Check(mBuffer);
614 1709 : PacketBuffer * buffer = mBuffer;
615 1709 : mBuffer = nullptr;
616 1709 : return buffer;
617 : }
618 :
619 : /**
620 : * Allocates a packet buffer.
621 : *
622 : * A packet buffer is conceptually divided into two parts:
623 : * @li Space reserved for network protocol headers. The size of this space normally defaults to a value determined
624 : * by the network layer configuration, but can be given explicity by \c aReservedSize for special cases.
625 : * @li Space for application data. The minimum size of this space is given by \c aAvailableSize, and then \c Start()
626 : * provides a pointer to the start of this space.
627 : *
628 : * Fails and returns \c nullptr if no memory is available, or if the size requested is too large.
629 : * When the sum of \a aAvailableSize and \a aReservedSize is no greater than \c PacketBuffer::kMaxSizeWithoutReserve,
630 : * that is guaranteed not to be too large.
631 : *
632 : * On success, it is guaranteed that \c AvailableDataSize() is no less than \a aAvailableSize.
633 : *
634 : * @param[in] aAvailableSize Minimum number of octets to for application data (at `Start()`).
635 : * @param[in] aReservedSize Number of octets to reserve for protocol headers (before `Start()`).
636 : *
637 : * @return On success, a PacketBufferHandle to the allocated buffer. On fail, \c nullptr.
638 : */
639 : static PacketBufferHandle New(size_t aAvailableSize, uint16_t aReservedSize = PacketBuffer::kDefaultHeaderReserve);
640 :
641 : /**
642 : * Allocates a packet buffer with initial contents.
643 : *
644 : * @param[in] aData Initial buffer contents.
645 : * @param[in] aDataSize Size of initial buffer contents.
646 : * @param[in] aAdditionalSize Size of additional application data space after the initial contents.
647 : * @param[in] aReservedSize Number of octets to reserve for protocol headers.
648 : *
649 : * @return On success, a PacketBufferHandle to the allocated buffer. On fail, \c nullptr.
650 : */
651 : static PacketBufferHandle NewWithData(const void * aData, size_t aDataSize, size_t aAdditionalSize = 0,
652 : uint16_t aReservedSize = PacketBuffer::kDefaultHeaderReserve);
653 :
654 : /**
655 : * Creates a copy of a packet buffer (or chain).
656 : *
657 : * @returns empty handle on allocation failure. Otherwise, the returned buffer has the same sizes and contents as the original.
658 : */
659 : PacketBufferHandle CloneData() const;
660 :
661 : /**
662 : * Perform an implementation-defined check on the validity of a PacketBufferHandle.
663 : *
664 : * Unless enabled by #CHIP_CONFIG_MEMORY_DEBUG_CHECKS == 1, this function does nothing.
665 : *
666 : * When enabled, it performs an implementation- and configuration-defined check on
667 : * the validity of the packet buffer. It MAY log an error and/or abort the program
668 : * if the packet buffer or the implementation-defined memory management system is in
669 : * a faulty state. (Some configurations may not actually perform any check.)
670 : *
671 : * @note A null handle is not considered faulty.
672 : */
673 : void Check() const
674 : {
675 : #if CHIP_SYSTEM_PACKETBUFFER_HAS_CHECK
676 : PacketBuffer::Check(mBuffer);
677 : #endif
678 : }
679 :
680 : bool operator==(const PacketBufferHandle & aOther) const { return mBuffer == aOther.mBuffer; }
681 :
682 : protected:
683 : #if CHIP_SYSTEM_CONFIG_USE_LWIP
684 : // For use via LwIPPacketBufferView only.
685 : static struct pbuf * GetLwIPpbuf(const PacketBufferHandle & handle)
686 : {
687 : PacketBuffer::Check(handle.mBuffer);
688 : return static_cast<struct pbuf *>(handle.mBuffer);
689 : }
690 : #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
691 :
692 : private:
693 : PacketBufferHandle(const PacketBufferHandle &) = delete;
694 : PacketBufferHandle & operator=(const PacketBufferHandle &) = delete;
695 :
696 : // The caller's ownership is transferred to this.
697 50394 : explicit PacketBufferHandle(PacketBuffer * buffer) : mBuffer(buffer) {}
698 :
699 0 : static PacketBufferHandle Hold(PacketBuffer * buffer)
700 : {
701 0 : if (buffer != nullptr)
702 : {
703 0 : buffer->AddRef();
704 : }
705 0 : return PacketBufferHandle(buffer);
706 : }
707 :
708 : PacketBuffer * Get() const { return mBuffer; }
709 : PacketBuffer * GetNext() const { return static_cast<PacketBuffer *>(mBuffer->next); }
710 :
711 : #if CHIP_SYSTEM_PACKETBUFFER_HAS_RIGHTSIZE
712 : void InternalRightSize();
713 : #endif
714 :
715 : PacketBuffer * mBuffer;
716 :
717 : friend class PacketBuffer;
718 : friend class TestSystemPacketBuffer;
719 : };
720 :
721 23252 : inline void PacketBuffer::SetDataLength(size_t aNewLen, const PacketBufferHandle & aChainHead)
722 : {
723 23252 : SetDataLength(aNewLen, aChainHead.mBuffer);
724 23252 : }
725 :
726 : inline PacketBufferHandle PacketBuffer::Next()
727 : {
728 : return PacketBufferHandle::Hold(ChainedBuffer());
729 : }
730 :
731 0 : inline PacketBufferHandle PacketBuffer::Last()
732 : {
733 0 : PacketBuffer * p = this;
734 0 : while (p->HasChainedBuffer())
735 0 : p = p->ChainedBuffer();
736 0 : return PacketBufferHandle::Hold(p);
737 : }
738 :
739 : } // namespace System
740 :
741 : namespace Encoding {
742 :
743 : class PacketBufferWriterUtil
744 : {
745 : private:
746 : template <typename>
747 : friend class PacketBufferWriterBase;
748 : static System::PacketBufferHandle Finalize(BufferWriter & aBufferWriter, System::PacketBufferHandle & aPacket);
749 : };
750 :
751 : /**
752 : * BufferWriter backed by packet buffer.
753 : *
754 : * Typical use:
755 : * @code
756 : * PacketBufferWriter buf(maximumLength);
757 : * if (buf.IsNull()) { return CHIP_ERROR_NO_MEMORY; }
758 : * buf.Put(...);
759 : * ...
760 : * PacketBufferHandle handle = buf.Finalize();
761 : * if (buf.IsNull()) { return CHIP_ERROR_BUFFER_TOO_SMALL; }
762 : * // valid data
763 : * @endcode
764 : */
765 : template <class Writer>
766 : class PacketBufferWriterBase : public Writer
767 : {
768 : public:
769 : /**
770 : * Constructs a BufferWriter that writes into a packet buffer, using all available space.
771 : *
772 : * @param[in] aPacket A handle to PacketBuffer, to be used as backing store for the BufferWriter.
773 : */
774 17 : PacketBufferWriterBase(System::PacketBufferHandle && aPacket) :
775 17 : Writer(aPacket->Start() + aPacket->DataLength(), aPacket->AvailableDataLength())
776 : {
777 17 : mPacket = std::move(aPacket);
778 17 : }
779 :
780 : /**
781 : * Constructs a BufferWriter that writes into a packet buffer, using no more than the requested space.
782 : *
783 : * @param[in] aPacket A handle to PacketBuffer, to be used as backing store for the BufferWriter.
784 : * @param[in] aSize Maximum number of octects to write into the packet buffer.
785 : */
786 44 : PacketBufferWriterBase(System::PacketBufferHandle && aPacket, size_t aSize) :
787 44 : Writer(aPacket->Start() + aPacket->DataLength(), std::min(aSize, static_cast<size_t>(aPacket->AvailableDataLength())))
788 : {
789 44 : mPacket = std::move(aPacket);
790 44 : }
791 :
792 : /**
793 : * Test whether this PacketBufferWriter is null, or conversely owns a PacketBuffer.
794 : *
795 : * @retval true The PacketBufferWriter is null; it does not own a PacketBuffer. This implies either that
796 : * construction failed, or that \c Finalize() has previously been called to release the buffer.
797 : * @retval false The PacketBufferWriter owns a PacketBuffer, which can be written using BufferWriter \c Put() methods,
798 : * and (assuming no overflow) obtained by calling \c Finalize().
799 : */
800 44 : bool IsNull() const { return mPacket.IsNull(); }
801 :
802 : /**
803 : * Obtain the backing packet buffer, if it is valid.
804 : *
805 : * If construction succeeded, \c Finalize() has not already been called, and \c BufferWriter::Fit() is true,
806 : * the caller takes ownership of a buffer containing the desired data. Otherwise, the returned handle tests null,
807 : * and any underlying storage has been released.
808 : *
809 : * @return A packet buffer handle.
810 : */
811 61 : System::PacketBufferHandle Finalize() { return PacketBufferWriterUtil::Finalize(*this, mPacket); }
812 :
813 : private:
814 : System::PacketBufferHandle mPacket;
815 : };
816 :
817 : using PacketBufferWriter = PacketBufferWriterBase<chip::Encoding::BufferWriter>;
818 :
819 : namespace LittleEndian {
820 : using PacketBufferWriter = PacketBufferWriterBase<chip::Encoding::LittleEndian::BufferWriter>;
821 : } // namespace LittleEndian
822 :
823 : namespace BigEndian {
824 : using PacketBufferWriter = PacketBufferWriterBase<chip::Encoding::BigEndian::BufferWriter>;
825 : } // namespace BigEndian
826 :
827 : } // namespace Encoding
828 :
829 : } // namespace chip
830 :
831 : #if CHIP_SYSTEM_CONFIG_USE_LWIP
832 :
833 : namespace chip {
834 :
835 : namespace Inet {
836 : class UDPEndPointImplLwIP;
837 : } // namespace Inet
838 :
839 : namespace System {
840 :
841 : /**
842 : * Provide low-level access to a raw `pbuf *`, limited to specific classes that interface with LwIP.
843 : */
844 : class LwIPPacketBufferView : public PacketBufferHandle
845 : {
846 : private:
847 : /**
848 : * Borrow a raw LwIP `pbuf *`.
849 : *
850 : * @brief The caller has access but no ownership.
851 : *
852 : * @note This should be used ONLY by low-level code interfacing with LwIP.
853 : */
854 : static struct pbuf * UnsafeGetLwIPpbuf(const PacketBufferHandle & handle) { return PacketBufferHandle::GetLwIPpbuf(handle); }
855 : friend class Inet::UDPEndPointImplLwIP;
856 : };
857 :
858 : } // namespace System
859 : } // namespace chip
860 :
861 : #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
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